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Find video protocols related to scientific articles indexed in Pubmed.
Pharmacological Intervention through Dietary Nutraceuticals in Gastrointestinal Neoplasia.
Crit Rev Food Sci Nutr
PUBLISHED: 11-04-2014
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Abstract Neoplastic conditions associated with gastrointestinal (GI) tract are common worldwide with colorectal cancer alone accounting for the third leading rate of cancer incidence. Other GI malignancies such as esophageal carcinoma have shown an increasing trend in the last few years. The poor survival statistics of these fatal cancer diseases highlight the need for multiple alternative treatment options along with effective prophylactic strategies. Worldwide geographical variation in cancer incidence indicates a correlation between dietary habits and cancer risk. Epidemiological studies have suggested that populations with high intake of certain dietary agents in their regular meals have lower cancer rates. Thus an impressive embodiment of evidence supports the concept that dietary factors are key modulators of cancer including those of GI origin. Preclinical studies on animal models of carcinogenesis have reflected the pharmacological significance of certain dietary agents called as nutraceuticals in the chemoprevention of GI neoplasia. These include stilbenes (from red grapes and red wine), isoflavones (from soy), carotenoids (from tomatoes), curcuminoids (from spice turmeric), catechins (from green tea) and various other small plant metabolites (from fruits, vegetables and cereals). Pleiotropic action mechanisms have been reported for these diet-derived chemopreventive agents to retard, block or reverse carcinogenesis. This review presents a prophylactic approach to primary prevention of GI cancers by highlighting the translational potential of plant-derived nutraceuticals from epidemiological, laboratory and clinical studies, for the better management of these cancers through consumption of nutraceutical rich diets and their intervention in cancer therapeutics.
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Androgen receptor splice variants contribute to prostate cancer aggressiveness through induction of EMT and expression of stem cell marker genes.
Prostate
PUBLISHED: 06-06-2014
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The mechanism(s) by which androgen receptor (AR) splice variants contribute to castration-resistant prostate cancer (CRPC) is still lacking.
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Differentially expressed miRNAs in cancer-stem-like cells: markers for tumor cell aggressiveness of pancreatic cancer.
Stem Cells Dev.
PUBLISHED: 06-06-2014
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Pancreatic cancer (PC) is one of the most deadly cancers. The higher mortality is in part due to treatment resistance and early onset of metastasis. The existence of cancer-stem-like cells (CSLCs) has been widely accepted to be responsible for tumor aggressiveness in PC. Emerging evidence suggests that CSLCs have the capacity for increased cell growth, cell migration/invasion, metastasis, and treatment resistance, which leads to poor clinical outcome. However, the molecular role of CSLCs in tumor development and progression is poorly understood. Therefore, mechanistic understanding, and targeted killing of CSLCs may provide a newer therapeutic strategy for the treatment of PC. It has been well accepted that microRNAs (miRNAs) play critical roles during tumor development and progression through deregulation of multiple genes. Moreover, deregulated expression of miRNAs may also play a key role in the regulation of CSLC characteristics and functions. Here we show that isolated CD44(+)/CD133(+)/EpCAM(+) cells (triple-marker-positive cells) from human PC cell lines, MiaPaCa-2 and L3.6pl cells, display aggressive characteristics, such as increased cell growth, clonogenicity, cell migration, and self-renewal capacity, which is consistent with overexpression of CSLC signatures/markers. We also found deregulated expression of over 400 miRNAs, including let-7, miR-30, miR-125b, and miR-335, in CSLCs. As a proof-of-concept, knockdown of miR-125b resulted in the inhibition of tumor cell aggressiveness of CSLCs (triple-marker-positive cells), consistent with the downregulation of CD44, EpCAM, EZH2, and snail. These results clearly suggest the importance of miRNAs in the regulation of CSLC characteristics, and may serve as novel targets for therapy.
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The therapeutic potential of targeting the epithelial-mesenchymal transition in cancer.
Expert Opin. Ther. Targets
PUBLISHED: 04-23-2014
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The process of epithelial-to-mesenchymal transition (EMT) has long been advocated as a process during tumor progression and the acquisition of metastatic potential of human cancers. EMT has also been linked with resistance to cancer therapies.
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Deregulation of miR-146a expression in a mouse model of pancreatic cancer affecting EGFR signaling.
Cancer Lett.
PUBLISHED: 04-09-2014
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Aberrant expression of microRNAs (miRNAs) plays important roles in the development and progression of pancreatic cancer (PC). Expression analysis of miR-146a in human PC tissues showed decreased expression in about 80% of samples compared to corresponding non-cancerous tissue. Moreover, expression of miR-146a in eight PC cell lines, and in pancreatic tissues obtained from transgenic mouse models of K-Ras (K), Pdx1-Cre (C), K-Ras;Pdx1-Cre (KC) and K-Ras;Pdx1-Cre;INK4a/Arf (KCI), showed down-regulation of miR-146a expression in KCI mice which was in part led to over-expression of its target gene, epidermal growth factor receptor (EGFR). Treatment of PC cells with CDF, a novel synthetic compound, led to re-expression of miR-146a, resulting in the down-regulation of EGFR expression. Moreover, re-expression of miR-146a by stable transfection or treatment with CDF in vivo (xenograft animal model) resulted in decreased tumor growth which was consistent with reduced EGFR, ERK1, ERK2, and K-Ras expression. Further knock-down of miR-146a in AsPC-1 cells led to the up-regulation of EGFR expression and showed increased clonogenic growth. In addition, knock-down of EGFR by EGFR siRNA transfection of parental AsPC-1 cells and AsPC-1 cells stably transfected with pre-miR-146a resulted in decreased invasive capacity, which was further confirmed by reduced luciferase activity in cells transfected with pMIR-Luc reporter vector containing miR-146a binding site. Collectively, these results suggest that the loss of expression of miR-146a is a fundamental mechanism for over-expression of EGFR signaling and that re-expression of miR-146a by CDF treatment could be useful in designing personalized strategy for the treatment of human PC.
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Pancreatic cancer stem-like cells display aggressive behavior mediated via activation of FoxQ1.
J. Biol. Chem.
PUBLISHED: 04-09-2014
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Subpopulations of cancer stem cells (CSCs) or cancer stem-like cells (CSLCs) have been identified from most tumors, including pancreatic cancer (PC), and the existence of these cells is clinically relevant. Emerging evidence suggests that CSLCs participate in cell growth/proliferation, migration/invasion, metastasis, and chemo-radiotherapy resistance, ultimately contributing to poor clinical outcome. However, the pathogenesis and biological significance of CSLCs in PC has not been well characterized. In the present study, we found that isolated triple-marker-positive (CD44(+)/CD133(+)/EpCAM(+)) cells of human PC MiaPaCa-2 and L3.6pl cells behave as CSLCs. These CSLCs exhibit aggressive behavior, such as increased cell growth, migration, clonogenicity, and self-renewal capacity. The mRNA expression profiling analysis showed that CSLCs (CD44(+)/CD133(+)/EpCAM(+)) exhibit differential expression of more than 1,600 mRNAs, including FoxQ1, compared with the triple-marker-negative (CD44(-)/CD133(-)/EpCAM(-)) cells. The knockdown of FoxQ1 by its siRNA in CSLCs resulted in the inhibition of aggressive behavior, consistent with the inhibition of EpCAM and Snail expression. Mouse xenograft tumor studies showed that CSLCs have a 100-fold higher potential for tumor formation and rapid tumor growth, consistent with overexpression of CSC-associated markers/mediators, including FoxQ1, compared with its parental MiaPaCa-2 cells. The inhibition of FoxQ1 attenuated tumor formation and growth, and expression of CSC markers in the xenograft tumor derived from CSLCs of MiaPaCa-2 cells. These data clearly suggest the role of differentially expressed genes in the regulation of CSLC characteristics, further suggesting that targeting some of these genes could be important for the development of novel therapies for achieving better treatment outcome of PC.
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Metformin may function as anti-cancer agent via targeting cancer stem cells: the potential biological significance of tumor-associated miRNAs in breast and pancreatic cancers.
Ann Transl Med
PUBLISHED: 02-19-2014
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Metformin is one of the most used diabetic drugs for the management of type II diabetes mellitus (DM) in the world. Increased numbers of epidemiological and clinical studies have provided convincing evidence supporting the role of metformin in the development and progression of a variety of human tumors including breast and pancreatic cancer. Substantial pre-clinical evidence from in vitro and in vivo experimental studies strongly suggests that metformin has an anti-cancer activity mediated through the regulation of several cell signaling pathways including activation of AMP kinase (AMPK), and other direct and indirect mechanisms; however, the detailed mechanism(s) has not yet been fully understood. The concept of cancer stem cells (CSCs) has gained significant attention in recent years due its identification and defining its clinical implications in many different tumors including breast cancer and pancreatic cancer. In this review, we will discuss the protective role of metformin in the development of breast and pancreatic cancers. We will further discuss the role of metformin as an anti-cancer agent, which is in part mediated through targeting CSCs. Finally, we will discuss the potential role of metformin in the modulation of tumor-associated or CSC-associated microRNAs (miRNAs) as part of the novel mechanism of action of metformin in the development and progression of breast and pancreatic cancers.
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MicroRNAs in breast cancer therapy.
Curr. Pharm. Des.
PUBLISHED: 01-28-2014
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Breast cancer is one of the most common type of cancers as well as a principal cause of cancer-related deaths in women worldwide. Although research has provided a better understanding and diagnosis of breast cancer, studies in breast cancer therapeutics are still far from satisfactory. Recent research on microRNAs (miRNAs) has implicated these tiny regulatory molecules in progression of breast cancer with the possibility of exploiting them as diagnostic and/or prognostic biomarkers. The loss of tumor suppressor miRNAs or overexpression of oncogenic miRNAs can lead to breast cancer tumorigenesis or metastasis. However, the next step - linking miRNAs to cancer therapeutics - is still under progression. The roles of miRNAs exhibit much potential in breast cancer therapy, but currently need to be further studied and evaluated in order to better understand how to apply laboratory results to clinical medicine. Here we provide an update on our current understanding of miRNAs as molecular targets for diagnosis, prognosis and therapy of breast cancers.
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Up-regulation of microRNA-10b is associated with the development of breast cancer brain metastasis.
Am J Transl Res
PUBLISHED: 01-01-2014
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Brain metastases from primary breast cancer are difficult to treat and associated with poor prognosis. Our understanding of the molecular basis for the development of such cancers is sparse. We hypothesized that the pro-metastatic microRNA-10b (miR-10b) plays a role in breast cancer brain metastasis. The study cohort comprised of twenty patients with breast cancer and brain metastasis as well as ten control patients (age, stage, and follow-up matched) with breast cancer without brain metastasis. All cases were microscopically reviewed to select tumor blocks with >50% tumor cells. RNA was extracted from formalin fixed paraffin embedded (FFPE) tumor tissue blocks. Expression of miR-10b was analyzed using qRT-PCR. The relevance of miR-10b expression was also tested using human breast cancer cell lines. An increased expression of miR-10b was noted in the primary breast cancer specimens of patients who subsequently developed brain metastasis, compared to those who did not. miR-10b also increased the invasive potential of breast cancer cells in vitro. Wilcoxon signed rank test revealed a statistically significant difference between the paired tumors from breast cancers and brain metastasis (p <0.001). Increased expression of miR-10b appears to be associated with breast cancer brain metastasis. These findings are clinically relevant since miR-10b could serve as a prognostic and/or therapeutic target for anti-metastatic therapy. Identifying molecular signatures of primary breast cancers which have a propensity for brain metastasis is critical for designing novel therapies to counter the development of brain metastasis in patients diagnosed with breast cancer.
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Comparative in vivo evaluations of curcumin and its analog difluorinated curcumin against cisplatin-induced nephrotoxicity.
Biol Trace Elem Res
PUBLISHED: 01-01-2014
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Curcumin, a polyphenol, has pharmacological effects including antioxidant, anti-inflammatory and anti-cancer features. In this study, we have performed comparative in vivo evaluations of CDF (curcumin difluorinated) and curcumin in cisplatin-induced nephrotoxicity in rats. Male Wistar rats were divided into four groups: (1) Control; (2) Cisplatin (7 mg/kg body wt, intraperitoneal as a single dose); (3) Cisplatin and CDF (50 mg/rat/day; for 12 days); (4) Cisplatin and curcumin (50 mg/rat/day), for 12 days). Cisplatin treated rats exhibited kidney injury manifested by increased serum N-urea and creatinine (P??curcumin). CDF could reduce the expression of multi-drug resistance markers OCT1, OCT2, MRP2 and MRP4 to a much greater extent than curcumin (P?
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Chemoresistance to gemcitabine in hepatoma cells induces epithelial-mesenchymal transition and involves activation of PDGF-D pathway.
Oncotarget
PUBLISHED: 10-26-2013
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Hepatocellular carcinoma (HCC) is one of the common malignances in the world and has high mortality in part due to development of acquired drug resistance. Therefore, it is urgent to investigate the molecular mechanism of drug resistance in HCC. To explore the underlying mechanism of drug resistance in HCC, we developed gemcitabine-resistant (GR) HCC cells. We used multiple methods to achieve our goal including RT-PCR, Western blotting analysis, transfection, Wound-healing assay, migration and invasion assay. We observed that gemcitabine-resistant cells acquired epithelial-mesenchymal transition (EMT) phenotype. Moreover, we found that PDGF-D is highly expressed in GR cells. Furthermore, down-regulation of PDGF-D in GR cells led to partial reversal of the EMT phenotype. Our findings demonstrated that targeting PDGF-D could be a novel strategy to overcome gemcitabine resistance in HCC.
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DIM (3,3-diindolylmethane) confers protection against ionizing radiation by a unique mechanism.
Proc. Natl. Acad. Sci. U.S.A.
PUBLISHED: 10-14-2013
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DIM (3,3-diindolylmethane), a small molecule compound, is a proposed cancer preventive agent that can be safely administered to humans in repeated doses. We report that administration of DIM in a multidose schedule protected rodents against lethal doses of total body irradiation up to 13 Gy, whether DIM dosing was initiated before or up to 24 h after radiation. Physiologic submicromolar concentrations of DIM protected cultured cells against radiation by a unique mechanism: DIM caused rapid activation of ataxia-telangiectasia mutated (ATM), a nuclear kinase that regulates responses to DNA damage (DDR) and oxidative stress. Subsequently, multiple ATM substrates were phosphorylated, suggesting that DIM induces an ATM-dependent DDR-like response, and DIM enhanced radiation-induced ATM signaling and NF-?B activation. DIM also caused activation of ATM in rodent tissues. Activation of ATM by DIM may be due, in part, to inhibition of protein phosphatase 2A, an upstream regulator of ATM. In contrast, DIM did not protect human breast cancer xenograft tumors against radiation under the conditions tested. In tumors, ATM was constitutively phosphorylated and was not further stimulated by radiation and/or DIM. Our findings suggest that DIM is a potent radioprotector and mitigator that functions by stimulating an ATM-driven DDR-like response and NF-?B survival signaling.
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Clinical Implication of MicroRNAs in Molecular Pathology.
Clin. Lab. Med.
PUBLISHED: 10-09-2013
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MicroRNAs are small endogenous noncoding RNAs that are critical regulators of several physiologic and pathologic processes including cancers. Variations in the level of microRNA expression have been linked with the development, progression, and spread of cancer to distant organs. These tiny molecules may play a role in accurate and early diagnosis, and also as prognostic determinants. Modulating their activity provides opportunities for developing and designing novel cancer therapeutics. Recent studies indicate their detection in a wide variety of human biologic specimens including blood, serum, fine-needle aspirates, and tissues, making them clinically useful biomarkers of disease for early detection, prognosis, and for designing personalized therapies.
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Radioprotection of lung tissue by soy isoflavones.
J Thorac Oncol
PUBLISHED: 10-01-2013
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Radiation-induced pneumonitis and fibrosis have restricted radiotherapy for lung cancer. In a preclinical lung tumor model, soy isoflavones showed the potential to enhance radiation damage in tumor nodules and simultaneously protect normal lung from radiation injury. We have further dissected the role of soy isoflavones in the radioprotection of lung tissue.
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Novel strategies targeting cancer stem cells through phytochemicals and their analogs.
Drug Deliv Transl Res
PUBLISHED: 10-01-2013
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Cancer stem cells (CSCs) are cells that exist within a tumor with a capacity of self-renewal and an ability to differentiate, giving rise to heterogeneous populations of cancer cells. These cells are increasingly being implicated in resistance to conventional therapeutics and have also been implicated in tumor recurrence. Several cellular signaling pathways including Notch, Wnt, phosphoinositide-3-kinase-Akt-mammalian target of rapamycin pathways, and known markers such as CD44, CD133, CD166, ALDH, etc. have been associated with CSCs. Here, we have reviewed our current understanding of self-renewal pathways and factors that help in the survival of CSCs with special emphasis on those that have been documented to be modulated by well characterized natural agents such as curcumin, sulforaphane, resveratrol, genistein, and epigallocatechin gallate. With the inclusion of a novel derivative of curcumin, CDF, we showcase how natural agents can be effectively modified to increase their efficacy, particularly against CSCs. We hope that this article will generate interest among researchers for further mechanistic and clinical studies exploiting the cancer preventive and therapeutic role of nutraceuticals by targeted elimination of CSCs.
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Epigenetic regulation of miRNA-cancer stem cells nexus by nutraceuticals.
Mol Nutr Food Res
PUBLISHED: 07-20-2013
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Nutraceuticals, the bioactive food components represented by many naturally occurring dietary compounds, have been investigated for a few decades for their numerous beneficial effects, including their anticancer properties. The initial interest in the cancer-preventing/therapeutic ability of these agents was based on their ability to affect multiple signaling pathways that are deregulated in cancer cells. With a shift in the focus of cancer research to the emerging areas such as epigenetic regulation, microRNAs (miRNAs) and the cancer stem cells (CSCs), nutraceuticals initially appeared out of place. However, research investigations over the last several years have slowly but firmly presented evidence that supports a relevance of these agents in modern day research. While nutraceuticals are increasingly being realized to alter miRNA/CSCs expression and function, the molecular mechanism(s) are not very clearly understood. Epigenetic regulation is one mechanism by which these agents exert their anticancer effects. In this focused mini review, we summarize our current understanding of epigenetic regulation of miRNAs and CSCs by nutraceuticals. We discuss both direct and indirect evidences that support such an activity of these compounds.
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Inhibition of Hedgehog signaling sensitizes NSCLC cells to standard therapies through modulation of EMT-regulating miRNAs.
J Hematol Oncol
PUBLISHED: 07-17-2013
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Epidermal growth factor receptor- tyrosine kinase inhibitors (EGFR-TKIs) benefit Non-small cell lung cancer (NSCLC) patients, and an EGFR-TKIi erlotinib, is approved for patients with recurrent NSCLC. However, resistance to erlotinib is a major clinical problem. Earlier we have demonstrated the role of Hedgehog (Hh) signaling in Epithelial-to-Mesenchymal transition (EMT) of NSCLC cells, leading to increased proliferation and invasion. Here, we investigated the role of Hh signaling in erlotinib resistance of TGF-ß1-induced NSCLC cells that are reminiscent of EMT cells.
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Regulating miRNA by natural agents as a new strategy for cancer treatment.
Curr Drug Targets
PUBLISHED: 06-28-2013
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MicroRNAs (miRNAs) are small single-strand non-coding endogenous RNAs that regulate gene expression by multiple mechanisms. Recent evidence suggests that miRNAs are critically involved in the pathogenesis, evolution, and progression of cancer. The miRNAs are also crucial for the regulation of cancer stem cells (CSCs). In addition, miRNAs are known to control the processes of Epithelial-to-Mesenchymal Transition (EMT) of cancer cells. This evidence suggests that miRNAs could serve as targets in cancer treatment, and as such manipulating miRNAs could be useful for the killing CSCs or reversal of EMT phenotype of cancer cells. Hence, targeting miRNAs, which are deregulated in cancer, could be a promising strategy for cancer therapy. Recently, the regulation of miRNAs by natural, nontoxic chemopreventive agents including curcumin, resveratrol, isoflavones, (-)-epigallocatechin-3-gallate (EGCG), lycopene, 3,3- diindolylmethane (DIM), and indole-3-carbinol (I3C) has been described. Therefore, natural agents could inhibit cancer progression, increase drug sensitivity, reverse EMT, and prevent metastasis though modulation of miRNAs, which will provide a newer therapeutic approach for cancer treatment especially when combined with conventional therapeutics.
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Genistein down-regulates miR-223 expression in pancreatic cancer cells.
Curr Drug Targets
PUBLISHED: 06-28-2013
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Although genistein has been shown to inhibit tumorigenesis in a variety of human cancers including pancreatic cancer (PC), the exact molecular mechanism of its anti-cancer effects has not yet been fully elucidated. Recently, microRNAs (miRNAs) have been reported to regulate multiple aspects of tumor development and progression, indicating that targeting miRNAs could be a novel strategy to treat human cancers. In the current study, we investigated whether a natural compound genistein could down-regulate onco-miR-223, resulting in the inhibition of cell growth and invasion, and induction of apoptosis in PC cells. We found that genistein treatment significantly inhibited miR-223 expression and up-regulated Fbw7, one of the targets of miR-223. Moreover, down-regulation of miR-223 inhibited cell growth and induced apoptosis in PC cells. These findings suggest that genistein exerts its anti-tumor activity partly through downregulation of miR-223 in PC cells.
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Functional role of miR-34 family in human cancer.
Curr Drug Targets
PUBLISHED: 06-28-2013
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Recently, microRNAs (miRNAs) including miR-34 family have been found to play a critical role in tumorigenesis through regulating the expression of its target genes, which are involved in many cellular processes such as cell proliferation, survival, apoptosis, migration, invasion and angiogenesis. Thus, this review described the role of miR-34 family and how its deregulation is involved in the development and progression of human malignances. Moreover, we described the potential role of miR-34 as a novel biomarker for tumor diagnosis. Furthermore, we summarized that miR-34 family could be up-regulated by natural compounds in human cancers. Therefore, targeting miR-34 family could be a novel strategy for achieving better treatment outcome of cancer patients in the future.
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Overview of cancer stem cells (CSCs) and mechanisms of their regulation: implications for cancer therapy.
Curr Protoc Pharmacol
PUBLISHED: 06-08-2013
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The identification of small subpopulations of cancer stem cells (CSCs) from blood mononuclear cells in human acute myeloid leukemia (AML) in 1997 was a landmark observation that recognized the potential role of CSCs in tumor aggressiveness. Two critical properties contribute to the functional role of CSCs in the establishment and recurrence of cancerous tumors: their capacity for self-renewal and their potential to differentiate into unlimited heterogeneous populations of cancer cells. These findings suggest that CSCs may represent novel therapeutic targets for the treatment and/or prevention of tumor progression, since they appear to be involved in cell migration, invasion, metastasis, and treatment resistance-all of which lead to poor clinical outcomes. The identification of CSC-specific markers, the isolation and characterization of CSCs from malignant tissues, and targeting strategies for the destruction of CSCs provide a novel opportunity for cancer research. This overview describes the potential implications of several common CSC markers in the identification of CSC subpopulations that are restricted to common malignant diseases, e.g., leukemia, and breast, prostate, pancreatic, and lung cancers. The role of microRNAs (miRNAs) in the regulation of CSC function is also discussed, as are several methods commonly used in CSC research. The potential role of the antidiabetic drug metformin- which has been shown to have effects on CSCs, and is known to function as an antitumor agent-is discussed as an example of this new class of chemotherapeutics.
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Plant polyphenol induced cell death in human cancer cells involves mobilization of intracellular copper ions and reactive oxygen species generation: A mechanism for cancer chemopreventive action.
Mol Nutr Food Res
PUBLISHED: 06-06-2013
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Anticancer polyphenolic nutraceuticals from fruits, vegetables, and spices are generally recognized as antioxidants, but can be prooxidants in the presence of copper ions. We earlier proposed a mechanism for such activity of polyphenols and now we provide data in multiple cancer cell lines in support of our hypothesis.
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Tumor cell-mediated neovascularization and lymphangiogenesis contrive tumor progression and cancer metastasis.
Biochim. Biophys. Acta
PUBLISHED: 06-04-2013
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Robust neovascularization and lymphangiogenesis have been found in a variety of aggressive and metastatic tumors. Endothelial sprouting angiogenesis is generally considered to be the major mechanism by which new vasculature forms in tumors. However, increasing evidence shows that tumor vasculature is not solely composed of endothelial cells (ECs). Some tumor cells acquire processes similar to embryonic vasculogenesis and produce new vasculature through vasculogenic mimicry, trans-differentiation of tumor cells into tumor ECs, and tumor cell-EC vascular co-option. In addition, tumor cells secrete various vasculogenic factors that induce sprouting angiogenesis and lymphangiogenesis. Vasculogenic tumor cells actively participate in the formation of vascular cancer stem cell niche and a premetastatic niche. Therefore, tumor cell-mediated neovascularization and lymphangiogenesis are closely associated with tumor progression, cancer metastasis, and poor prognosis. Vasculogenic tumor cells have emerged as key players in tumor neovascularization and lymphangiogenesis and play pivotal roles in tumor progression and cancer metastasis. However, the mechanisms underlying tumor cell-mediated vascularity as they relate to tumor progression and cancer metastasis remain unclear. Increasing data have shown that various intrinsic and extrinsic factors activate oncogenes and vasculogenic genes, enhance vasculogenic signaling pathways, and trigger tumor neovascularization and lymphangiogenesis. Collectively, tumor cells are the instigators of neovascularization. Therefore, targeting vasculogenic tumor cells, genes, and signaling pathways will open new avenues for anti-tumor vasculogenic and metastatic drug discovery. Dual targeting of endothelial sprouting angiogenesis and tumor cell-mediated neovascularization and lymphangiogenesis may overcome current clinical problems with anti-angiogenic therapy, resulting in significantly improved anti-angiogenesis and anti-cancer therapies.
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Exosomes in cancer development, metastasis, and drug resistance: a comprehensive review.
Cancer Metastasis Rev.
PUBLISHED: 05-28-2013
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Trafficking of biological material across membranes is an evolutionary conserved mechanism and is part of any normal cell homeostasis. Such transport is composed of active, passive, export through microparticles, and vesicular transport (exosomes) that collectively maintain proper compartmentalization of important micro- and macromolecules. In pathological states, such as cancer, aberrant activity of the export machinery results in expulsion of a number of key proteins and microRNAs resulting in their misexpression. Exosome-mediated expulsion of intracellular drugs could be another barrier in the proper action of most of the commonly used therapeutics, targeted agents, and their intracellular metabolites. Over the last decade, a number of studies have revealed that exosomes cross-talk and/or influence major tumor-related pathways, such as hypoxia-driven epithelial-to-mesenchymal transition, cancer stemness, angiogenesis, and metastasis involving many cell types within the tumor microenvironment. Emerging evidence suggests that exosome-secreted proteins can also propel fibroblast growth, resulting in desmoplastic reaction, a major barrier in effective cancer drug delivery. This comprehensive review highlights the advancements in the understanding of the biology of exosomes secretions and the consequence on cancer drug resistance. We propose that the successful combination of cancer treatments to tackle exosome-mediated drug resistance requires an interdisciplinary understanding of these cellular exclusion mechanisms, and how secreted biomolecules are involved in cellular cross-talk within the tumor microenvironment.
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Regulation of EMT by Notch Signaling Pathway in Tumor Progression.
Curr Cancer Drug Targets
PUBLISHED: 05-10-2013
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Notch signaling pathway has been reported to play critical roles in the development and progression of human cancers because Notch signaling pathway is critically involved in many cellular processes including cell proliferation, survival, apoptosis, migration, invasion, angiogenesis, and metastasis. Emerging evidence suggests that Notch regulates EMT (Epithelial-to-Mesenchymal Transition), leading to tumor invasion and metastasis. Thus, this mini-review is focused on discussing the novel role of Notch signaling pathway in the regulation of EMT. Moreover, we summarized that Notch signaling pathway could be down-regulated by its inhibitors or natural compounds, resulting in the reversal of EMT to MET (Mesenchymal-to-Epithelial Transition), which could be a promising strategy for achieving better treatment outcome in patients diagnosed with cancer.
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Clinical advances in molecular biomarkers for cancer diagnosis and therapy.
Int J Mol Sci
PUBLISHED: 05-09-2013
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Cancer diagnosis is currently undergoing a paradigm shift with the incorporation of molecular biomarkers as part of routine diagnostic panel. The molecular alteration ranges from those involving the DNA, RNA, microRNAs (miRNAs) and proteins. The miRNAs are recently discovered small non-coding endogenous single-stranded RNAs that critically regulates the development, invasion and metastasis of cancers. They are altered in cancers and have the potential to serve as diagnostic markers for cancer. Moreover, deregulating their activity offers novel cancer therapeutic approaches. The availability of high throughput techniques for the identification of altered cellular molecules allowed their use in cancer diagnosis. Their application to a variety of body specimens from blood to tissues has been helpful for appreciating their use in the clinical context. The development of innovative antibodies for immunohistochemical detection of proteins also assists in diagnosis and risk stratification. Overall, the novel cancer diagnostic tools have extended their application as prognostic risk factors and can be used as targets for personalized medicine.
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Tumour vasculogenic mimicry is associated with poor prognosis of human cancer patients: a systemic review and meta-analysis.
Eur. J. Cancer
PUBLISHED: 04-22-2013
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Vasculogenic mimicry (VM) has been reported in various malignant tumours and is known to play an important role in cancer progression and metastasis. However, the impact of VM on the overall survival of human cancer patients remains controversial. The goal of this study was to evaluate whether VM is associated with 5-year survival of human cancer patients.
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Systems analysis reveals a transcriptional reversal of the mesenchymal phenotype induced by SNAIL-inhibitor GN-25.
BMC Syst Biol
PUBLISHED: 04-12-2013
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HMLEs (HMLE-SNAIL and Kras-HMLE, Kras-HMLE-SNAIL pairs) serve as excellent model system to interrogate the effect of SNAIL targeted agents that reverse epithelial-to-mesenchymal transition (EMT). We had earlier developed a SNAIL-p53 interaction inhibitor (GN-25) that was shown to suppress SNAIL function. In this report, using systems biology and pathway network analysis, we show that GN-25 could cause reversal of EMT leading to mesenchymal-to-epithelial transition (MET) in a well-recognized HMLE-SNAIL and Kras-HMLE-SNAIL models.
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Perspectives on the role of isoflavones in prostate cancer.
AAPS J
PUBLISHED: 04-02-2013
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Isoflavones have been investigated in detail for their role in the prevention and therapy of prostate cancer. This is primarily because of the overwhelming data connecting high dietary isoflavone intake with reduced risk of developing prostate cancer. A number of investigations have evaluated the mechanism(s) of anticancer action of isoflavones such as genistein, daidzein, biochanin A, equol, etc., in various prostate cancer models, both in vitro and in vivo. Genistein quickly jumped to the forefront of isoflavone cancer research, but the initial enthusiasm was followed by reports on its contradictory prometastatic and tumor-promoting effects. Use of soy isoflavone mixture has been advocated as an alternative, wherein daidzein can negate harmful effects of genistein. Recent research indicates a novel role of genistein and other isoflavones in the potentiation of radiation therapy, epigenetic regulation of key tumor suppressors and oncogenes, and the modulation of miRNAs, epithelial-to-mesenchymal transition, and cancer stem cells, which has renewed the interest of cancer researchers in this class of anticancer compounds. This comprehensive review article summarizes our current understanding of the role of isoflavones in prostate cancer research.
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A molecular rheostat at the interface of cancer and diabetes.
Biochim. Biophys. Acta
PUBLISHED: 03-25-2013
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Epidemiology studies revealed the connection between several types of cancer and type 2 diabetes (T2D) and suggested that T2D is both a symptom and a risk factor of pancreatic cancer. High level of circulating insulin (hyperinsulinemia) in obesity has been implicated in promoting aggressive types of cancers. Insulin resistance, a symptom of T2D, pressures pancreatic ?-cells to increase insulin secretion, leading to hyperinsulinemia, which in turn leads to a gradual loss of functional ?-cell mass, thus indicating a fine balance and interplay between ?-cell function and mass. While the mechanisms of these connections are unclear, the mTORC1-Akt signaling pathway has been implicated in controlling ?-cell function and mass, and in mediating the link of cancer and T2D. However, incomplete understating of how the pathway is regulated and how it integrates body metabolism has hindered its efficacy as a clinical target. The IQ motif containing GTPase activating protein 1 (IQGAP1)-Exocyst axis is a growth factor- and nutrient-sensor that couples cell growth and division. Here we discuss how IQGAP1-Exocyst, through differential interactions with Rho-type of small guanosine triphosphatases (GTPases), acts as a rheostat that modulates the mTORC1-Akt and MAPK signals, and integrates ?-cell function and mass with insulin signaling, thus providing a molecular mechanism for cancer initiation in diabetes. Delineating this regulatory pathway may have the potential of contributing to optimizing the efficacy and selectivity of future therapies for cancer and diabetes.
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Differential effect of soy isoflavones in enhancing high intensity radiotherapy and protecting lung tissue in a pre-clinical model of lung carcinoma.
Radiother Oncol
PUBLISHED: 03-18-2013
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Radiotherapy of locally-advanced non-small cell lung cancer is limited by radiation-induced pneumonitis and fibrosis. We have further investigated the role of soy isoflavones to improve the effect of a high intensity radiation and reduce lung damage in a pre-clinical lung tumor model.
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Comprehensive molecular oncogenomic profiling and miRNA analysis of prostate cancer.
Am J Transl Res
PUBLISHED: 01-24-2013
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This study was focused on molecular profiling of prostate cancer (PCa) using scant amounts of both frozen and formalin-fixed paraffin-embedded (FFPE) PCa tissue specimens. DNA and RNA were extracted and interrogated for: (1) whole-genome gene expression profiling, (2) miRNA expression analysis, (3) SNP analysis, and (4) mutation analysis. Data was statistically analyzed and correlated with clinical and pathologic variables. Expression profiling of 47,224 genes revealed 74 genes that were significant in predicting high tumor grade in PCa (p<0.0001). These were involved in many cellular processes as analyzed by Ingenuity Pathway Analysis (IPA). Using novel high throughput technologies, we identified a specific oncogenomic and miRNA signatures showing loss of miR-34 expression. Interestingly, p53 was at the center hub of the signaling pathways, and the loss of miR-34a expression was consistent with the central role of p53 in PCa. Analysis of 731,442 SNPs, revealed 638 SNPs that were significant in predicting high tumor grade (p<0.0001; logistic regression analysis). We also found, for the first time, a novel hot spot mutation in MET oncogene, variant T992I, suggesting that our findings would be useful in further defining the role of specific regulatory genes and miRNAs in the pathological evolution of PCa, and could also have potential clinical utility in improving diagnostic accuracy, refining prognostic and predictive capabilities and may serve as therapeutic targets.
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CXCR2 macromolecular complex in pancreatic cancer: a potential therapeutic target in tumor growth.
Transl Oncol
PUBLISHED: 01-17-2013
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The signaling mediated by the chemokine receptor CXC chemokine receptor 2 (CXCR2) plays an important role in promoting the progression of many cancers, including pancreatic cancer, one of the most lethal human malignancies. CXCR2 possesses a consensus PSD-95/DlgA/ZO-1 (PDZ) motif at its carboxyl termini, which might interact with potential PDZ scaffold/adaptor proteins. We have previously reported that CXCR2 PDZ motif-mediated protein interaction is an important regulator for neutrophil functions. Here, using a series of biochemical assays, we demonstrate that CXCR2 is physically coupled to its downstream effector phospholipase C-?3 (PLC-?3) that is mediated by PDZ scaffold protein Na(+)/H(+) exchange regulatory factor 1 (NHERF1) into a macromolecular signaling complex both in vitro and in pancreatic cancer cells. We also observe that disrupting the CXCR2 complex, by gene delivery or peptide delivery of exogenous CXCR2 C-tail, significantly inhibits the biologic functions of pancreatic cancer cells (i.e., proliferation and invasion) in a PDZ motif-dependent manner. In addition, using a human pancreatic tumor xenograft model, we show that gene delivery of CXCR2 C-tail sequence (containing the PDZ motif) by adeno-associated virus type 2 viral vector potently suppresses human pancreatic tumor growth in immunodeficient mice. In summary, our results suggest the existence of a physical and functional coupling of CXCR2 and PLC-?3 mediated through NHERF1, forming a macromolecular complex that is critical for efficient and specific CXCR2 signaling in pancreatic cancer progression. Disrupting this CXCR2 complex could represent a novel and effective treatment strategy against pancreatic cancer.
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Down-regulation of miR-21 Induces Differentiation of Chemoresistant Colon Cancer Cells and Enhances Susceptibility to Therapeutic Regimens.
Transl Oncol
PUBLISHED: 01-16-2013
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MicroRNAs are endogenous posttranscriptional modulators that negatively control the expression of their target genes and play an important role in the development and progression of many malignancies, including colorectal carcinoma. In particular, expression of microRNA-21 (miR-21) is greatly increased in chemotherapy-resistant (CR) colon cancer cells that are enriched in undifferentiated cancer stem/stem-like cells (CSCs/CSLCs). We hypothesize that miR-21 plays a critical role in regulating differentiation of CR colon cancer cells. Indeed, we observed that downregulation of miR-21 in CR colon cancer cells (HCT-116 or HT-29) by antisense miR-21 induced differentiation, as evidenced by marked increases in cytokeratin-20 (CK-20) expression and alkaline phosphatase activity. These changes were accompanied by a significant reduction in the expression of colon CSC/CSLC marker CD44, colonosphere formation, and T-cell factor/lymphoid enhancer factor (TCF/LEF) activity but increased the expression of proapoptotic programmed cell death 4 gene. Induction of differentiation greatly increased sensitivity of CR colon cancer cells to the growth inhibitory properties of all three regimens tested: 5-fluorouracil + oxaliplatin (FUOX), difluorinated curcumin (CDF), and the combination of CDF and FUOX. However, the magnitude of inhibition of growth by either CDF (75%) alone or CDF + FUOX (80%) was much higher than that observed with only FUOX (40%). Growth inhibition by CDF and CDF + FUOX in differentiating CR colon cancer cells was associated with a 98% to 99% reduction in the expression of CD44 and epidermal growth factor receptor (EGFR). However, down-regulation of CK-20 in CR colon cancer cells produced no significant change in cellular growth in the absence or presence of FUOX, when compared with the corresponding controls. The current observation suggests that CDF and CDF + FUOX are highly effective in inhibiting growth and reducing colon CSCs/CSLCs in anti-miR-21-induced differentiating CR colon cancer cells and supports our contention that differentiation enhances susceptibility of CR cancer cells to conventional and nonconventional therapeutic regimen.
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Synthesis, characterization and anti-tumor activity of novel thymoquinone analogs against pancreatic cancer.
Bioorg. Med. Chem. Lett.
PUBLISHED: 01-09-2013
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Thymoquinone (TQ), isolated from the seeds of Nigella sativa, show moderate efficacy against pancreatic cancer. In the present work we report synthesis and characterization of novel TQ analogs appended with gallate and fluorogallate pharmacophores and evaluation of their effects against pancreatic cancer cell lines for cell viability and induction of apoptosis. The efficacy of the analogs alone or in combination with Gemcitabine was assessed in vitro. LC-MS spectra of ATQTHB and ATQTFB showed major peaks corresponding to expected M+1 fragment at 316.34 and 322.34 respectively. Molecular docking studies revealed good fit for these analogs in the COX-2 protein cavity with better binding energies compared to parent TQ compound. Present TQ analogs exhibit superior anti-proliferative activity, excellent chemo-sensitizing activity against pancreatic cancer in vitro and in combination with Gemcitabine.
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Unraveling the mystery of cancer metabolism in the genesis of tumor-initiating cells and development of cancer.
Biochim. Biophys. Acta
PUBLISHED: 01-06-2013
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Robust anaerobic metabolism plays a causative role in the origin of cancer cells; however, the oncogenic metabolic genes, factors, pathways, and networks in genesis of tumor-initiating cells (TICs) have not yet been systematically summarized. In addition, the mechanisms of oncogenic metabolism in the genesis of TICs are enigmatic. In this review, we discussed multiple cancer metabolism-related genes (MRGs) that are overexpressed in TICs and are responsible for inducing pluripotent stem cells. Moreover, we summarized that oncogenic metabolic genes and onco-metabolites induce metabolic reprogramming, which switches normal mitochondrial oxidative phosphorylation to cancer anaerobic metabolism, triggers epigenetic, genetic, and environmental alterations, drives the generation of TICs, and boosts the development of cancer. Importantly, cancer metabolism is controlled by positive and negative metabolic regulators. Positive oncogenic metabolic regulators, including key oncogenic metabolic genes, onco-metabolites, hypoxia, and an acidic environment, promote oncogenic metabolic reprogramming and anaerobic metabolism. However, dysfunction of negative metabolic regulators, including defects in p53, PTEN, and LKB1-AMPK-mTOR pathways, enhances cancer metabolism. Loss of the metabolic balance results in oncogenic metabolic reprogramming, genesis of TICs, and tumorigenesis. Collectively, this review provides new insight into the role and mechanism of these oncogenic metabolisms in the genesis of TICs and tumorigenesis. Accordingly, targeting key oncogenic genes, onco-metabolites, pathways, networks, and the acidic cancer microenvironment appears to be an attractive strategy for novel anti-tumor treatment.
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Pro-oxidant activity of dietary chemopreventive agents: an under-appreciated anti-cancer property.
F1000Res
PUBLISHED: 01-01-2013
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" Let food be thy medicine and medicine be thy food" was quoted by Hippocrates more than two thousand years ago and since ancient times the health benefits of different natural agents have been exploited. In modern research, the disease preventive benefits of many such natural agents, particularly dietary compounds and their derivatives, has been attributed to their well recognized activity as the regulators of redox state of the cell. Nevertheless, most of these studies have focused on their antioxidant activity. A large body of evidence indicates that a major fraction of these agents can elicit pro-oxidant (radical generating) behavior which has been linked to their anti-cancer effects. This editorial provides an overview of the under-appreciated pro-oxidant activity of natural products, with a special focus on their ability to generate reactive oxygen species in the presence of transition metal ions, and discusses their possible use as cancer chemotherapeutic agents.
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Mitochondrial dysfunction promotes breast cancer cell migration and invasion through HIF1? accumulation via increased production of reactive oxygen species.
PLoS ONE
PUBLISHED: 01-01-2013
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Although mitochondrial dysfunction has been observed in various types of human cancer cells, the molecular mechanism underlying mitochondrial dysfunction mediated tumorigenesis remains largely elusive. To further explore the function of mitochondria and their involvement in the pathogenic mechanisms of cancer development, mitochondrial dysfunction clones of breast cancer cells were generated by rotenone treatment, a specific inhibitor of mitochondrial electron transport complex I. These clones were verified by mitochondrial respiratory defect measurement. Moreover, those clones exhibited increased reactive oxygen species (ROS), and showed higher migration and invasive behaviors compared with their parental cells. Furthermore, antioxidant N-acetyl cysteine, PEG-catalase, and mito-TEMPO effectively inhibited cell migration and invasion in these clones. Notably, ROS regulated malignant cellular behavior was in part mediated through upregulation of hypoxia-inducible factor-1 ? and vascular endothelial growth factor. Our results suggest that mitochondrial dysfunction promotes cancer cell motility partly through HIF1? accumulation mediated via increased production of reactive oxygen species.
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Difluorinated-curcumin (CDF) restores PTEN expression in colon cancer cells by down-regulating miR-21.
PLoS ONE
PUBLISHED: 01-01-2013
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Despite recent advancement in medicine, nearly 50% of patients with colorectal cancer show recurrence of the disease. Although the reasons for the high relapse are not fully understood, the presence of chemo- and radiotherapy-resistant cancer stem/stem-like cells, where many oncomirs like microRNA-21 (miR-21) are upregulated, could be one of the underlying causes. miR-21 regulates the processes of invasion and metastasis by downregulating multiple tumor/metastatic suppressor genes including PTEN (phosphatase and tensin homolog). Tumor suppressor protein PTEN controls self-renewal of stem cells. Indeed, our current data demonstrate a marked downregulation of PTEN in SCID mice xenografts of miR-21 over-expressing colon cancer HCT116 cells. Colonospheres that are highly enriched in cancer stem/stem like cells reveal increased miR-21 expression and decreased PTEN. Difluorinated curcumin (CDF), a novel analog of the dietary ingredient curcumin, which has been shown to inhibit the growth of 5-Flurouracil + Oxaliplatin resistant colon cancer cells, downregulated miR-21 in chemo-resistant colon cancer HCT116 and HT-29 cells and restored PTEN levels with subsequent reduction in Akt phosphorylation. Similar results were also observed in metastatic colon cancer SW620 cells. Since PTEN-Akt confers drug resistance to different malignancies including colorectal cancer, our observation of normalization of miR-21-PTEN-Akt pathway by CDF suggests that the compound could be a potential therapeutic agent for chemotherapy-resistant colorectal cancer.
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Induction of cancer cell death by isoflavone: the role of multiple signaling pathways.
Nutrients
PUBLISHED: 12-27-2011
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Soy isoflavones have been documented as dietary nutrients broadly classified as "natural agents" which plays important roles in reducing the incidence of hormone-related cancers in Asian countries, and have shown inhibitory effects on cancer development and progression in vitro and in vivo, suggesting the cancer preventive or therapeutic activity of soy isoflavones against cancers. Emerging experimental evidence shows that isoflavones could induce cancer cell death by regulating multiple cellular signaling pathways including Akt, NF-?B, MAPK, Wnt, androgen receptor (AR), p53 and Notch signaling, all of which have been found to be deregulated in cancer cells. Therefore, homeostatic regulation of these important cellular signaling pathways by isoflavones could be useful for the activation of cell death signaling, which could result in the induction of apoptosis of both pre-cancerous and/or cancerous cells without affecting normal cells. In this article, we have attempted to summarize the current state-of-our-knowledge regarding the induction of cancer cell death pathways by isoflavones, which is believed to be mediated through the regulation of multiple cellular signaling pathways. The knowledge gained from this article will provide a comprehensive view on the molecular mechanism(s) by which soy isoflavones may exert their effects on the prevention of tumor progression and/or treatment of human malignancies, which would also aid in stimulating further in-depth mechanistic research and foster the initiation of novel clinical trials.
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Aberrant epigenetic grooming of miRNAs in pancreatic cancer: a systems biology perspective.
Epigenomics
PUBLISHED: 12-01-2011
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Pancreatic cancer (PC) is a complex disease harboring a myriad of genetic and epigenetic changes. The dismal survival of patients diagnosed with PC is in part due to de novo and acquired resistance to conventional therapeutics, resulting from deregulated signaling including aberrant expression of small nc miRNAs. Emerging research in this area has lead to the identification and characterization of deregulated miRNAs, which have generated a renewed interest and hope in that novel targeting of miRNAs may lead to a better clinical outcome for patients diagnosed with PC. However, recent evidence suggests that miRNAs are also under a highly coordinated system of epigenetic regulation emphasizing the fact that the design of miRNAs as targeted therapy may not be as simple as originally anticipated. For a successful miRNA-based therapeutic regimen, a holistic integrated approach may be required to take into account because of these emerging epigenetic regulatory mechanisms. In this article, we will discuss miRNA epigenetics, its significance in PC and the use of a systems science to identify these aberrant epigenetically groomed miRNAs, and we believe that such knowledge would likely benefit further research to realize the dream of miRNA-based targeted therapy for human malignancies.
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Curcumin analogue CDF inhibits pancreatic tumor growth by switching on suppressor microRNAs and attenuating EZH2 expression.
Cancer Res.
PUBLISHED: 11-22-2011
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The histone methyltransferase EZH2 is a central epigenetic regulator of cell survival, proliferation, and cancer stem cell (CSC) function. EZH2 expression is increased in various human cancers, including highly aggressive pancreatic cancers, but the mechanisms underlying for its biologic effects are not yet well understood. In this study, we probed EZH2 function in pancreatic cancer using diflourinated-curcumin (CDF), a novel analogue of the turmeric spice component curcumin that has antioxidant properties. CDF decreased pancreatic cancer cell survival, clonogenicity, formation of pancreatospheres, invasive cell migration, and CSC function in human pancreatic cancer cells. These effects were associated with decreased expression of EZH2 and increased expression of a panel of tumor-suppressive microRNAs (miRNA), including let-7a, b, c, d, miR-26a, miR-101, miR-146a, andmiR-200b, c that are typically lost in pancreatic cancer. Mechanistic investigations revealed that reexpression of miR-101 was sufficient to limit the expression of EZH2 and the proinvasive cell surface adhesion molecule EpCAM. In an orthotopic xenograft model of human pancreatic cancer, administration of CDF inhibited tumor growth in a manner associated with reduced expression of EZH2, Notch-1, CD44, EpCAM, and Nanog and increased expression of let-7, miR-26a, and miR-101. Taken together, our results indicated that CDF inhibited pancreatic cancer tumor growth and aggressiveness by targeting an EZH2-miRNA regulatory circuit for epigenetically controlled gene expression.
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Metformin inhibits cell proliferation, migration and invasion by attenuating CSC function mediated by deregulating miRNAs in pancreatic cancer cells.
Cancer Prev Res (Phila)
PUBLISHED: 11-15-2011
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Pancreatic cancer is the fourth leading cause of cancer-related deaths in the United States, which is, in part, due to intrinsic (de novo) and extrinsic (acquired) resistance to conventional therapeutics, suggesting that innovative treatment strategies are required for overcoming therapeutic resistance to improve overall survival of patients. Oral administration of metformin in patients with diabetes mellitus has been reported to be associated with reduced risk of pancreatic cancer and that metformin has been reported to kill cancer stem cells (CSC); however, the exact molecular mechanism(s) has not been fully elucidated. In the current study, we examined the effect of metformin on cell proliferation, cell migration and invasion, and self-renewal capacity of CSCs and further assessed the expression of CSC marker genes and microRNAs (miRNA) in human pancreatic cancer cells. We found that metformin significantly decreased cell survival, clonogenicity, wound-healing capacity, sphere-forming capacity (pancreatospheres), and increased disintegration of pancreatospheres in both gemcitabine-sensitive and gemcitabine-resistant pancreatic cancer cells. Metformin also decreased the expression of CSC markers,CD44, EpCAM,EZH2, Notch-1, Nanog and Oct4, and caused reexpression of miRNAs (let-7a,let-7b, miR-26a, miR-101, miR-200b, and miR-200c) that are typically lost in pancreatic cancer and especially in pancreatospheres. We also found that reexpression of miR-26a by transfection led to decreased expression of EZH2 and EpCAM in pancreatic cancer cells. These results clearly suggest that the biologic effects of metformin are mediated through reexpression of miRNAs and decreased expression of CSC-specific genes, suggesting that metformin could be useful for overcoming therapeutic resistance of pancreatic cancer cells.
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MicroRNA-21 induces stemness by downregulating transforming growth factor beta receptor 2 (TGF?R2) in colon cancer cells.
Carcinogenesis
PUBLISHED: 11-09-2011
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Although microRNA-21 (miR-21) is emerging as an oncogene and has been shown to target several tumor suppressor genes, including programmed cell death 4 (PDCD4), its precise mechanism of action on cancer stem cells (CSCs) is unclear. Herein, we report that FOLFOX-resistant HCT-116 and HT-29 cells that are enriched in CSCs show a 3- to 7-fold upregulation of pre- and mature miR-21 and downregulation of PDCD4. Likewise, overexpression of miR-21 in HCT-116 cells, achieved through stable transfection, led to the downregulation of PDCD4 and transforming growth factor beta receptor 2 (TGF?R2). In contrast, the levels of ?-catenin, TCF/LEF activity and the expression of c-Myc, Cyclin-D, which are increased in CSCs, are also augmented in miR-21 overexpressing colon cancer cells, accompanied by an increased sphere forming ability in vitro and tumor formation in SCID mice. Downregulation of TGF?R2 could be attributed to decreased expression of the receptor as evidenced by reduction in the activity of the luciferase gene construct comprising TGF?R2-3 untranslated region (UTR) sequence that binds to miR-21. Moreover, we observed that downregulation of miR-21 enhances luciferase-TGF?R2-3 UTR activity suggesting TGF?R2 as being one of the direct targets of miR-21. Further support is provided by the observation that transfection of TGF?R2 in HCT-116 cells attenuates TCF/LEF luciferase activity, accompanied by decreased expression of ?-catenin, c-Myc and Cyclin-D1. Our current data suggest that miR-21 plays an important role in regulating stemness by modulating TGF?R2 signaling in colon cancer cells.
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B-DIM impairs radiation-induced survival pathways independently of androgen receptor expression and augments radiation efficacy in prostate cancer.
Cancer Lett.
PUBLISHED: 10-10-2011
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Increased consumption of cruciferous vegetables is associated with decreased risk in prostate cancer (PCa). The active compound in cruciferous vegetables appears to be the self dimerized product [3,3-diindolylmethane (DIM)] of indole-3-carbinol (I3C). Nutritional grade B-DIM (absorption-enhanced) has proven safe in a Phase I trial in PCa. We investigated the anti-cancer activity of B-DIM as a new biological approach to improve the effects of radiotherapy for hormone refractory prostate cancer cells, which were either positive or negative for androgen receptor (AR) expression. B-DIM inhibited cell growth in a dose-dependent manner in both PC-3 (AR-) and C4-2B (AR+) cell lines. B-DIM was effective at increasing radiation-induced cell killing in both cell lines, independently of AR expression. B-DIM inhibited NF-?B and HIF-1? DNA activities and blocked radiation-induced activation of these transcription factors in both PC-3 and C4-2B cells. In C4-2B (AR+) cells, AR expression and nuclear localization were significantly increased by radiation. However, B-DIM abrogated the radiation-induced AR increased expression and trafficking to the nucleus, which was consistent with decreased PSA secretion. In vivo, treatment of PC-3 prostate tumors in nude mice with B-DIM and radiation resulted in significant primary tumor growth inhibition and control of metastasis to para-aortic lymph nodes. These studies demonstrate that B-DIM augments radiation-induced cell killing and tumor growth inhibition. B-DIM impairs critical survival signaling pathways activated by radiation, leading to enhanced cell killing. These novel observations suggest that B-DIM could be used as a safe compound to enhance the efficacy of radiotherapy for castrate-resistant PCa.
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The immunological contribution of NF-?B within the tumor microenvironment: a potential protective role of zinc as an anti-tumor agent.
Biochim. Biophys. Acta
PUBLISHED: 09-26-2011
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Over decades, cancer treatment has been mainly focused on targeting cancer cells and not much attention to host tumor microenvironment. Recent advances suggest that the tumor microenvironment requires in-depth investigation for understanding the interactions between tumor cell biology and immunobiology in order to optimize therapeutic approaches. Tumor microenvironment consists of cancer cells and tumor associated reactive fibroblasts, infiltrating non-cancer cells, secreted soluble factors or molecules, and non-cellular support materials. Tumor associated host immune cells such as Th(1), Th(2), Th17, regulatory cells, dendritic cells, macrophages, and myeloid-derived suppressor cells are major components of the tumor microenvironment. Accumulating evidence suggests that these tumor associated immune cells may play important roles in cancer development and progression. However, the exact functions of these cells in the tumor microenvironment are poorly understood. In the tumor microenvironment, NF-?B plays an important role in cancer development and progression because this is a major transcription factor which regulates immune functions within the tumor microenvironment. In this review, we will focus our discussion on the immunological contribution of NF-?B in tumor associated host immune cells within the tumor microenvironment. We will also discuss the potential protective role of zinc, a well-known immune response mediator, in the regulation of these immune cells and cancer cells in the tumor microenvironment especially because zinc could be useful for conditioning the tumor microenvironment toward innovative cancer therapy.
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Cancer selective metallocenedicarboxylates of the fungal cytotoxin illudin M.
J. Med. Chem.
PUBLISHED: 08-30-2011
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The diester 2a obtained from 1,1-ferrocenedicarboxylic acid and the highly and indiscriminately cytotoxic fungal metabolite illudin M (1) displayed antiproliferative activity at submicromolar IC(50) (72 h) values against a panel of eight cancer cell lines. Compound 2a was about 40 times less toxic than 1 to nonmalignant human foreskin fibroblasts (HF). The analogous bis(illudinyl M) 1,1-ruthenocenedicarboxylate (2b) exhibited submicromolar IC(50) (72 h) values only against MDA-MB-231 and MCF-7/Topo breast carcinoma and HL-60 leukemia cells. Cytotoxicity studies in the presence of inhibitors of c-Jun N-terminal kinase (JNK) or extracellular signal-regulated kinase (ERK) revealed that the high efficacy of 2a, but not that of 2b, against HCT-116 colon cancer cells depends on active JNK/ERK signaling. A new illudin M lactone 5 was of low anticancer activity, but its ruthenocene diester 6b also reached single-digit micromolar IC(50) (72 h) values in HCT-116, MCF-7, and HL-60 leukemia cells while not affecting HF. Compounds 2a and 6b were tolerated by mice symptom-free at single doses as high as 25 mg/kg body weight, which is evidence for them being chemically stable under physiological conditions. Compound 2a displayed a manageable in vivo toxicity profile when given repeatedly in high doses.
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Skp2: a novel potential therapeutic target for prostate cancer.
Biochim. Biophys. Acta
PUBLISHED: 08-16-2011
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Prostate cancer is the most frequently diagnosed tumor in men and the second most common cause of cancer-related death for males in the United States. It has been shown that multiple signaling pathways are involved in the pathogenesis of prostate cancer, such as androgen receptor (AR), Akt, Wnt, Hedgehog (Hh) and Notch. Recently, burgeoning amounts of evidence have implicated that the F-box protein Skp2 (S-phase kinase associated protein 2), a well-characterized oncoprotein, also plays a critical role in the development and progression of prostate cancer. Therefore, this review discusses the recent literature regarding the function and regulation of Skp2 in the pathogenesis of prostate cancer. Furthermore, we highlight that Skp2 may represent an attractive therapeutic target, thus warrants further development of agents to target Skp2, which could have significant therapeutic impact on prostate cancer.
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Emerging roles of the FBW7 tumour suppressor in stem cell differentiation.
EMBO Rep.
PUBLISHED: 07-25-2011
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FBW7 is a ubiquitin E3 ligase substrate adaptor that targets many important oncoproteins-such as Notch, c-Myc, cyclin E and c-Jun-for ubiquitin-dependent proteolysis. By doing so, it plays crucial roles in many cellular processes, including cell cycle progression, cell growth, cellular metabolism, differentiation and apoptosis. Loss of FBW7 has been observed in many types of human cancer, and its role as a tumour suppressor was confirmed by genetic ablation of FBW7 in mice, which leads to the induction of tumorigenesis. How FBW7 exerts its tumour suppression function, and whether loss of FBW7 leads to de-differentiation or acquisition of stemness-a process frequently seen in human carcinomas-remains unclear. Emerging evidence shows that FBW7 controls stem cell self-renewal, differentiation, survival and multipotency in various stem cells, including those of the haematopoietic and nervous systems, liver and intestine. Here, we focus on the function of FBW7 in stem cell differentiation, and its potential relevance to human disease and therapeutics.
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Soy isoflavones radiosensitize lung cancer while mitigating normal tissue injury.
Radiother Oncol
PUBLISHED: 07-18-2011
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We have demonstrated that soy isoflavones radiosensitize cancer cells. Prostate cancer patients receiving radiotherapy (RT) and soy tablets had reduced radiation toxicity to surrounding organs. We have now investigated the combination of soy with RT in lung cancer (NSCLC), for which RT is limited by radiation-induced pneumonitis.
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Network modeling of CDF treated pancreatic cancer cells reveals a novel c-myc-p73 dependent apoptotic mechanism.
Am J Transl Res
PUBLISHED: 06-29-2011
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Systems biology and molecular network modeling are important tools that are finding application in anti-cancer drug discovery. These technologies can be utilized to map and evaluate the entire set of pathways modulated by drugs in cancer cells without loosing key details. Such integrated approaches are especially useful in understanding the mechanism of action of agents that do not have a defined target. Our novel compound CDF (a synthetic analogue of curcumin), is one such multi-targeted agent with proven anti-cancer activity in vitro and in vivo. However, its mechanism of action is not fully understood, and thus a thorough analysis of key pathways targeted by CDF would be important for developing targeted and tailored therapy in the future. Applying Ingenuity Pathway Analysis (IPA), we have mapped the pathways altered by CDF treatment of BxPC-3 pancreatic cancer (PC) cells. Illumina HT-12 microar-rays were performed on RNA extracted from CDF treated cells. IPA analysis of gene expression at early time point (24 hrs) revealed deregulation of genes in the c-Myc hub. Western blot analysis validated the activation of c-Myc, p73 and its downstream pro-apoptotic effector Bax with simultaneous down-regulation of Bcl-2 in two distinct pancreatic cancer cell lines (BxPC-3 and Colo-357). In order to further delineate the role of c-Myc in inducing apoptosis, siRNA silencing technology was used. As expected, c-Myc siRNA knockdown resulted in abrogation of the growth inhibitory and apoptotic potential of CDF. In conclusion, our results demonstrate a novel c-Myc driven apoptotic network activated by CDF in PC cells that is independent of wild-type p53, and thus warrants further investigation on the clinical utility of CDF.
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A Th1 cytokine-enriched microenvironment enhances tumor killing by activated T cells armed with bispecific antibodies and inhibits the development of myeloid-derived suppressor cells.
Cancer Immunol. Immunother.
PUBLISHED: 06-18-2011
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In this study, we investigated whether activated T cells (ATC) armed with bispecific antibodies (aATC) can inhibits tumor growth and MDSC development in a Th1 cytokine-enriched (IL-2 and IFN-?) microenvironment. Cytotoxicity mediated by aATC was significantly higher (P < 0.001) against breast cancer cell lines in the presence of Th1 cytokines as compared with control co-cultures. In the presence of aATC, CD33+ /CD11b+ /CD14- /HLA-DR- MDSC population was reduced significantly under both control (P < 0.03) and Th1-enriched (P < 0.036) culture conditions. Cytokine analysis in the culture supernatants showed high levels of MDSC suppressive chemokines CXCL9 and CXCL10 in Th1-enriched culture supernatants with highly significant increase (P < 0.001) in the presence of aATC. Interestingly, MDSC recovered from co-cultures without aATC showed potent ability to suppress activated T-cell-mediated cytotoxicity (P < 0.001), IFN-? production (P < 0.01) and T-cell proliferation (P < 0.05) compared to those recovered from aATC-containing co-cultures. These data suggest that aATC can mediate enhanced killing of tumor cells and may suppress MDSC and T(reg) differentiation, and presence of Th() cytokines potentiates aATC-induced suppression of MDSC, suggesting that Th1-enriching immunotherapy may be beneficial in cancer treatment.
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Inactivation of AR/TMPRSS2-ERG/Wnt signaling networks attenuates the aggressive behavior of prostate cancer cells.
Cancer Prev Res (Phila)
PUBLISHED: 06-16-2011
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The development of prostate cancer and its progression to castrate-resistant prostate cancer (CRPC) after antiandrogen ablation therapy are driven by persistent biological activity of androgen receptor (AR) signaling. Moreover, studies have shown that more than 50% of human prostate cancers overexpress ERG (v-ets avian erythroblastosis virus E26 oncogene related gene) due to AR-regulated TMPRSS2-ERG fusion gene. However, the reported roles of TMPRSS2-ERG fusion in cancer progression are not clear. In this study, we investigated the signal transduction in the AR/TMPRSS2-ERG/Wnt signaling network for studying the aggressive behavior of prostate cancer cells and further assessed the effects of BR-DIM and CDF [natural agents-derived synthetic formulation and analogue of 3,3-diindolylmethane (DIM) and curcumin, respectively, with improved bioavailability] on the regulation of AR/TMPRSS2-ERG/Wnt signaling. We found that activation of AR resulted in the induction of ERG expression through TMPRSS2-ERG fusion. Moreover, we found that ERG overexpression and nuclear translocation activated the activity of Wnt signaling. Furthermore, forced overexpression of ERG promoted invasive capacity of prostate cancer cells. More important, we found that BR-DIM and CDF inhibited the signal transduction in the AR/TMPRSS2-ERG/Wnt signaling network, leading to the inactivation of Wnt signaling consistent with inhibition of prostate cancer cell invasion. In addition, BR-DIM and CDF inhibited proliferation of prostate cancer cells and induced apoptotic cell death. On the basis of our findings, we conclude that because BR-DIM and CDF downregulate multiple signaling pathways including AR/TMPRSS2-ERG/Wnt signaling, these agents could be useful for designing novel strategies for the prevention and/or treatment of prostate cancer.
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Cancer Stem Cells and Epithelial-to-Mesenchymal Transition (EMT)-Phenotypic Cells: Are They Cousins or Twins?
Cancers (Basel)
PUBLISHED: 06-07-2011
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Cancer stem cells (CSCs) are cells within a tumor that possess the capacity to self-renew and maintain tumor-initiating capacity through differentiation into the heterogeneous lineages of cancer cells that comprise the whole tumor. These tumor-initiating cells could provide a resource for cells that cause tumor recurrence after therapy. Although the cell origin of CSCs remains to be fully elucidated, mounting evidence has demonstrated that Epithelial-to-Mesenchymal Transition (EMT), induced by different factors, is associated with tumor aggressiveness and metastasis and these cells share molecular characteristics with CSCs, and thus are often called cancer stem-like cells or tumor-initiating cells. The acquisition of an EMT phenotype is a critical process for switching early stage carcinomas into invasive malignancies, which is often associated with the loss of epithelial differentiation and gain of mesenchymal phenotype. Recent studies have demonstrated that EMT plays a critical role not only in tumor metastasis but also in tumor recurrence and that it is tightly linked with the biology of cancer stem-like cells or cancer-initiating cells. Here we will succinctly summarize the state-of-our-knowledge regarding the molecular similarities between cancer stem-like cells or CSCs and EMT-phenotypic cells that are associated with tumor aggressiveness focusing on solid tumors.
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Attenuation of multi-targeted proliferation-linked signaling by 3,3-diindolylmethane (DIM): from bench to clinic.
Mutat. Res.
PUBLISHED: 06-06-2011
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Emerging evidence provide credible support in favor of the potential role of bioactive products derived from ingesting cruciferous vegetables such as broccoli, brussel sprouts, cauliflower and cabbage. Among many compounds, 3,3-diindolylmethane (DIM) is generated in the acidic environment of the stomach following dimerization of indole-3-carbinol (I3C) monomers present in these classes of vegetables. Both I3C and DIM have been investigated for their use in preventing, inhibiting, and reversing the progression of cancer - as a chemopreventive agent. In this review, we summarize an updated, wide-ranging pleiotropic anti-tumor and biological effects elicited by DIM against tumor cells. It is unfeasible to point one single target as basis of cellular target of action of DIM. We emphasize key cellular and molecular events that are effectively modulated in the direction of inducing apoptosis and suppressing cell proliferation. Collectively, DIM orchestrates signaling through Ah receptor, NF-?B/Wnt/Akt/mTOR pathways impinging on cell cycle arrest, modulation of key cytochrome P450 enzymes, altering angiogenesis, invasion, metastasis and epigenetic behavior of cancer cells. The ability of DIM to selectively induce tumor cells to undergo apoptosis has been observed in preclinical models, and thus it has been speculated in improving the therapeutic efficacy of other anticancer agents that have diverse molecular targets. Consequently, DIM has moved through preclinical development into Phase I clinical trials, thereby suggesting that DIM could be a promising and novel agent either alone or as an adjunct to conventional therapeutics such as chemo-radio and targeted therapies. An important development has been the availability of DIM formulation with superior bioavailability for humans. Therefore, DIM appears to be a promising chemopreventive agent or chemo-radio-sensitizer for the prevention of tumor recurrence and/or for the treatment of human malignancies.
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Network modeling of MDM2 inhibitor-oxaliplatin combination reveals biological synergy in wt-p53 solid tumors.
Oncotarget
PUBLISHED: 05-31-2011
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Earlier we had shown that the MDM2 inhibitor (MI-219) belonging to the spiro-oxindole family can synergistically enhance the efficacy of platinum chemotherapeutics leading to 50% tumor free survival in a genetically complex pancreatic ductaladenocarcinoma (PDAC) xenograft model. In this report, we have taken a systems and network modeling approach in order to understand central mechanisms behind MI219-oxaliplatin synergy with validation in PDAC, colon and breast cancer cell lines. Microarray profiling of drug treatments (MI-219, oxaliplatin or their combination) in capan-2 cells reveal a similar unique set of gene alterations that is duplicated in other solid tumor cells. As single agent, MI-219 or oxaliplatin induced alterations in 48 and 761 genes respectively. The combination treatment resulted in 767 gene alterations with emergence of 286 synergy unique genes. Ingenuity network modeling of combination and synergy unique genes showed the crucial role of five key local networks CREB, CARF, EGR1, NF-kB and E-Cadherin. Compared to single agents the combination treatment super induced p53 and p21 confirming functional synergy. Further, the network signatures were validated at the protein level in all three cell lines. Individually silencing central nodes in these five hubsinterfered with MI-219-oxaliplatin activity confirming their critical role in aiding p53 mediated apoptotic response. We anticipate that our MI219-oxaliplatin network blueprints can be clinically translated in the rationale design and application of this unique therapeutic combination in a genetically pre-defined subset of patients.
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Garcinol-induced apoptosis in prostate and pancreatic cancer cells is mediated by NF- kappaB signaling.
Front Biosci (Elite Ed)
PUBLISHED: 05-31-2011
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Garcinol, obtained from Garcinia indica, is a potent antioxidant. Its anticancer activity has been investigated; however, there is no published report on its action against prostate and pancreatic cancer cells. We have earlier reported its activity against breast cancer cells, and here we tested our hypothesis that garcinol could inhibit cell proliferation and induce apoptosis in prostate as well as pancreatic cancer cells. Using multiple techniques such as MTT, Histone-DNA ELISA, activated caspase assays, clonogenic assays and EMSA, we investigated the mechanism of apoptosis-inducing effect of garcinol in prostate (LNCaP, C4-2B and PC3) and pancreatic (BxPC-3) cancer cells. We found that garcinol inhibited cell growth of all the cell lines tested with a concomitant induction of apoptosis in a dose-dependent manner. Down-regulation of NF-kappaB signaling pathway appears to be the mechanism of apoptosis-induction because garcinol inhibited constitutive levels of NF-betaB activity, which was consistent with down-regulation of NF-betaB-regulated genes. A significant decrease in the colony forming ability of all the cell lines was also observed, suggesting the possible application of this compound against metastatic disease. In summary, our results provide pre-clinical evidence to support the use of garcinol against human prostate and pancreatic cancer, thus meriting its further investigation as a potential chemo-preventive and/or therapeutic agent.
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HDAC1 inhibition by maspin abrogates epigenetic silencing of glutathione S-transferase pi in prostate carcinoma cells.
Mol. Cancer Res.
PUBLISHED: 05-26-2011
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Both maspin and glutathione S-transferase pi (GSTp) are implicated as tumor suppressors and downregulated in human prostate cancer. It is well established that GSTp downregulation is through DNA methylation-based silencing. We report here that maspin expression in prostate cancer cell line DU145 reversed GSTp DNA methylation, as measured by methylation- specific PCR, MethyLight assay, and bisulfite sequencing. The effect of maspin on GSTp expression was similar to that of the combination of a synthetic histone deacetylase (HDAC) inhibitor and DNA methylation inhibitor 5-aza-2-deoxycytidine. Maspin expression also led to an increased level of acetylated histone 3, decreased level of methyl transferase, and methyl-CpG-binding domain proteins at the site of demethylated GSTp promoter DNA. Earlier, we have shown that maspin inhibits HDAC1. In PC3 cells, where both maspin and GSTp are expressed at a reduced level, maspin knockdown led to a significant reduction in GSTp expression, whereas dual knockdown of maspin and HDAC1 barely increased the level of GSTp expression. Thus, HDAC1 may play an essential role in cellular response to maspin-mediated GSTp desilencing. Maspin has been shown to increase tumor cell sensitivity to drug-induced apoptosis. Interestingly, GSTp reexpression in the absence of maspin expression perturbation blocked the phosphorylation of histone 2A.X, the induction of hypoxia-induced factor 1? (HIF-1?), and cell death of LNCaP cells under oxidative stress. Because DNA hypermethylation-based silencing may couple with and depend on histone deacetylation, our study suggests that endogenous HDAC inhibition by maspin may prevent pathologic gene silencing in prostate tumor progression.
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Inhibition of cell growth and induction of apoptosis in non-small cell lung cancer cells by delta-tocotrienol is associated with notch-1 down-regulation.
J. Cell. Biochem.
PUBLISHED: 05-21-2011
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Lung cancer is the leading cause of death among all cancers. Non-small cell lung cancer accounts for 80% of lung cancer with a 5-year survival rate of 16%. Notch pathway, especially Notch-1 is up-regulated in a subgroup of non-small cell lung cancer patients. Since Notch-1 signaling plays an important role in cell proliferation, differentiation, and apoptosis, down-regulation of Notch-1 may exert anti-tumor effects. The objective of this study was to investigate whether delta-tocotrienol, a naturally occurring isoform of Vitamin E, inhibits non-small cell lung cancer cell growth via Notch signaling. Treatment with delta-tocotrienol resulted in a dose and time dependent inhibition of cell growth, cell migration, tumor cell invasiveness, and induction of apoptosis. Real-time RT-PCR and western blot analysis showed that antitumor activity by delta-tocotrienol was associated with a decrease in Notch-1, Hes-1, Survivin, MMP-9, VEGF, and Bcl-XL expression. In addition, there was a decrease in NF-?B-DNA binding activity. These results suggest that down-regulation of Notch-1, via inhibition of NF-?B signaling pathways by delta-tocotrienol, could provide a potential novel approach for prevention of tumor progression in non-small cell lung cancer.
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Targeting notch to eradicate pancreatic cancer stem cells for cancer therapy.
Anticancer Res.
PUBLISHED: 04-22-2011
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Pancreatic cancer is the most aggressive malignant disease once it is diagnosed and it remains the fourth leading cause of cancer-related death in the U.S.A. Recent data indicates that the Notch signaling pathway plays an important role in the development and progression of pancreatic cancer. Emerging evidence also suggests that the activation of the Notch signaling pathway is mechanistically associated with molecular characteristics of cancer stem cells (CSCs) in pancreatic cancer. Moreover, CSCs are known to be highly drug-resistant, suggesting that targeted inactivation of Notch signaling would be useful for overcoming drug resistance and the elimination of CSCs. This review describes the roles of the Notch signaling pathway in pancreatic cancer with a special emphasis on its novel functions in the regulation of pancreatic CSC. Moreover, the review also proposes that targeting the Notch signaling pathway by natural agents may represent a novel strategy for overcoming drug resistance and the elimination of CSCs, which would be useful for the successful treatment of patients diagnosed with pancreatic cancer.
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Molecular markers of epithelial-to-mesenchymal transition are associated with tumor aggressiveness in breast carcinoma.
Transl Oncol
PUBLISHED: 04-20-2011
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Epithelial-to-mesenchymal transition (EMT) is a transient process occurring during developmental stages and carcinogenesis, characterized by phenotypic and molecular alterations, resulting in increased invasive and metastatic capabilities of cancer cells and drug resistance. Moreover, emerging evidence suggests that EMT is associated with increased enrichment of cancer stem-like cells in neoplastic tissues. We interrogated the molecular alterations occurring in breast cancer using proposed EMT markers such as E-cadherin, vimentin, epidermal growth factor receptor (EGFR), platelet-derived growth factor (PDGF) D, and nuclear factor ? B (NF-? B) to decipher their roles in the EMT and breast cancer progression.
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Over-expression of FoxM1 leads to epithelial-mesenchymal transition and cancer stem cell phenotype in pancreatic cancer cells.
J. Cell. Biochem.
PUBLISHED: 04-20-2011
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FoxM1 is known to play important role in the development and progression of many malignancies including pancreatic cancer. Studies have shown that the acquisition of epithelial-to-mesenchymal transition (EMT) phenotype and induction of cancer stem cell (CSC) or cancer stem-like cell phenotypes are highly inter-related, and contributes to drug resistance, tumor recurrence, and metastasis. The molecular mechanism(s) by which FoxM1 contributes to the acquisition of EMT phenotype and induction of CSC self-renewal capacity is poorly understood. Therefore, we established FoxM1 over-expressing pancreatic cancer (AsPC-1) cells, which showed increased cell growth, clonogenicity, and cell migration. Moreover, over-expression of FoxM1 led to the acquisition of EMT phenotype by activation of mesenchymal cell markers, ZEB1, ZEB2, Snail2, E-cadherin, and vimentin, which is consistent with increased sphere-forming (pancreatospheres) capacity and expression of CSC surface markers (CD44 and EpCAM). We also found that over-expression of FoxM1 led to decreased expression of miRNAs (let-7a, let-7b, let-7c, miR-200b, and miR-200c); however, re-expression of miR-200b inhibited the expression of ZEB1, ZEB2, vimentin as well as FoxM1, and induced the expression of E-cadherin, leading to the reversal of EMT phenotype. Finally, we found that genistein, a natural chemo-preventive agent, inhibited cell growth, clonogenicity, cell migration and invasion, EMT phenotype, and formation of pancreatospheres consistent with reduced expression of CD44 and EpCAM. These results suggest, for the first time, that FoxM1 over-expression is responsible for the acquisition of EMT and CSC phenotype, which is in part mediated through the regulation of miR-200b and these processes, could be easily attenuated by genistein.
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Activated K-ras and INK4a/Arf deficiency cooperate during the development of pancreatic cancer by activation of Notch and NF-?B signaling pathways.
PLoS ONE
PUBLISHED: 04-12-2011
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Pancreatic ductal adenocarcinoma (PDAC) is the fourth leading cause of cancer-related death in the United States, suggesting that novel strategies for the prevention and treatment of PDAC are urgently needed. K-ras mutations are observed in >90% of pancreatic cancer, suggesting its role in the initiation and early developmental stages of PDAC. In order to gain mechanistic insight as to the role of mutated K-ras, several mouse models have been developed by targeting a conditionally mutated K-ras(G12D) for recapitulating PDAC. A significant co-operativity has been shown in tumor development and metastasis in a compound mouse model with activated K-ras and Ink4a/Arf deficiency. However, the molecular mechanism(s) by which K-ras and Ink4a/Arf deficiency contribute to PDAC has not been fully elucidated.
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Phosphoglucose isomerase/autocrine motility factor mediates epithelial-mesenchymal transition regulated by miR-200 in breast cancer cells.
Cancer Res.
PUBLISHED: 03-09-2011
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Phosphoglucose isomerase/autocrine motility factor (PGI/AMF) plays an important role in glycolysis and gluconeogenesis and is associated with invasion and metastasis of cancer cells. We have previously shown its role in the induction of epithelial-mesenchymal transition (EMT) in breast cancer cells, which led to increased aggressiveness; however, the molecular mechanism by which PGI/AMF regulates EMT is not known. Here we show, for the first time, that PGI/AMF overexpression led to an increase in the DNA-binding activity of NF-?B, which, in turn, led to increased expression of ZEB1/ZEB2. The microRNA-200s (miR-200s) miR-200a, miR-200b, and miR-200c are known to negatively regulate the expression of ZEB1/ZEB2, and we found that the expression of miR-200s was lost in PGI/AMF overexpressing MCF-10A cells and in highly invasive MDA-MB-231 cells, which was consistent with increased expression of ZEB1/ZEB2. Moreover, silencing of PGI/AMF expression in MDA-MB-231 cells led to overexpression of miR-200s, which was associated with reversal of EMT phenotype (i.e., mesenchymal-epithelial transition), and these findings were consistent with alterations in the relative expression of epithelial (E-cadherin) and mesenchymal (vimentin, ZEB1, ZEB2) markers and decreased aggressiveness as judged by clonogenic, motility, and invasion assays. Moreover, either reexpression of miR-200 or silencing of PGI/AMF suppressed pulmonary metastases of MDA-MB-231 cells in vivo, and anti-miR-200 treatment in vivo resulted in increased metastases. Collectively, these results suggest a role of miR-200s in PGI/AMF-induced EMT and thus approaches for upregulation of miR-200s could be a novel therapeutic strategy for the treatment of highly invasive breast cancer.
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Intracellular free zinc up-regulates IFN-? and T-bet essential for Th1 differentiation in Con-A stimulated HUT-78 cells.
Biochem. Biophys. Res. Commun.
PUBLISHED: 03-04-2011
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Zinc deficiency impairs cellular immunity. Up-regulation of mRNA levels of IFN-?, IL-12R?2, and T-bet are essential for Th(1) differentiation. We hypothesized that zinc increases Th(1) differentiation via up-regulation of IFN-? and T-bet expression. To test this hypothesis, we used zinc-deficient and zinc-sufficient HUT-78 cells (a Th(0) cell line) under different condition of stimulation in this study. We also used TPEN, a zinc-specific chelator, to decrease the bioavailability of zinc in the cells. We measured intracellular free zinc, cytokines, and the mRNAs of T-bet, IFN-?, and IL-12R?2. In this study, we show that in zinc-sufficient HUT-78 cells, mRNA levels of IFN-?, IL-12R?2, and T-bet in PMA/PHA-stimulated cells were increased in comparison to zinc-deficient cells. Although intracellular free zinc was increased slightly in PMA/PHA-stimulated cells, Con-A-stimulated cells in 5?M zinc medium showed a greater sustained increase in intracellular free zinc in comparison to cells incubated in 1?M zinc. The cells pre-incubated with TPEN showed decreased mRNA levels of IFN-? and T-bet mRNAs in comparison to cells without TPEN incubation. We conclude that stimulation of cells by Con-A via TCR, release intracellular free zinc which functions as a signal molecule for generation of IFN-? and T-bet, and IL-12R?2 mRNAs required for Th(1) cell differentiation. These results suggest that zinc increase Th(1) cell differentiation by up-regulation of IFN-? and T-bet, and IL-12Rb?2 mRNAs.
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Notch-1 induces epithelial-mesenchymal transition consistent with cancer stem cell phenotype in pancreatic cancer cells.
Cancer Lett.
PUBLISHED: 03-03-2011
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Activation of Notch-1 is known to be associated with the development and progression of human malignancies including pancreatic cancer. Emerging evidence suggest that the acquisition of epithelial-mesenchymal transition (EMT) phenotype and induction of cancer stem cell (CSC) or cancer stem-like cell phenotype are interrelated and contributes to tumor recurrence and drug resistance. The molecular mechanism(s) by which Notch-1 contributes to the acquisition of EMT phenotype and CSC self-renewal capacity has not been fully elucidated. Here we show that forced over-expression of Notch-1 leads to increased cell growth, clonogenicity, migration and invasion of AsPC-1 cells. Moreover, over-expression of Notch-1 led to the induction of EMT phenotype by activation of mesenchymal cell markers such as ZEB1, CD44, EpCAM, and Hes-1. Here we also report, for the first time, that over-expression of Notch-1 leads to increased expression of miR-21, and decreased expression of miR-200b, miR-200c, let-7a, let-7b, and let-7c. Re-expression of miR-200b led to decreased expression of ZEB1, and vimentin, and increased expression of E-cadherin. Over-expression of Notch-1 also increased the formation of pancreatospheres consistent with expression of CSC surface markers CD44 and EpCAM. Finally, we found that genistein, a known natural anti-tumor agent inhibited cell growth, clonogenicity, migration, invasion, EMT phenotype, formation of pancreatospheres and expression of CD44 and EpCAM. These results suggest that the activation of Notch-1 signaling contributes to the acquisition of EMT phenotype, which is in part mediated through the regulation of miR-200b and CSC self-renewal capacity, and these processes could be attenuated by genistein treatment.
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Network perspectives on HDM2 inhibitor chemotherapy combinations.
Curr. Pharm. Des.
PUBLISHED: 02-18-2011
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The discovery of small molecule inhibitors of HDM2-p53 interaction is considered one of the most significant therapeutic developments in the area p53 research. Intensive work on different classes of HDM2 inhibitors has proven their therapeutic utility as activators of p53 in multiple tumor models. Many laboratories have shown that HDM2 inhibitors can synergize with chemotherapeutic agents resulting in enhanced efficacy through both p53-dependent and independent mechanisms. In our hands HDM2 inhibitor and platinum drug combination showed remarkable antitumor activity that led tumor free survival in one of the most resistant and complex pancreatic xenograft models. Although antitumor efficacy of such combinations has been studied in detail, not much is known on the molecular mechanisms governing this synergy. This is partly due to complexity of multiple pathways modulated by p53 and HDM2. We are of the view that in order to decode this complexity, an integrated approach is needed that considers both HDM2 and p53 as components of a network and not in isolation. This review highlights recent advancements in our understanding of HDM2 inhibitor combination therapy based on network modeling and systems biology driven science. Our recent findings support such a network view as integrated gene expression profiling and pathway network modeling on MI-219-oxaliplatin treated cells revealed activation of multiple and closely knit biological networks. We anticipate that in the near future such network-centric approaches will benefit clinical development of HDM2 inhibitors for genetically predefined subsets of cancer patients and this will be a step towards personalized medicine.
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Soy isoflavones augment radiation effect by inhibiting APE1/Ref-1 DNA repair activity in non-small cell lung cancer.
J Thorac Oncol
PUBLISHED: 02-18-2011
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Soy isoflavones sensitize cancer cells to radiation both in vitro and in vivo. To improve the effect of radiotherapy for non-small cell lung cancer, we assessed the potential of using a complementary approach with soy isoflavones.
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Inhibitory effect of curcumin on oral carcinoma CAL-27 cells via suppression of Notch-1 and NF-?B signaling pathways.
J. Cell. Biochem.
PUBLISHED: 02-11-2011
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Curcumin has been reported to inhibit cell growth and induce apoptosis in oral cancer cells. Although many studies have been done to uncover the mechanisms by which curcumin exerts its antitumor activity, the precise molecular mechanisms remain to be unclear. In the present study, we assessed the effects of curcumin on cell viability and apoptosis in oral cancer. For mechanistic studies, we used multiple cellular and molecular approaches such as gene transfection, real-time RT-PCR, Western blotting, invasion assay, and ELISA. For the first time, we found a significant reduction in cell viability in curcumin-treated cells, which was consistent with induction of apoptosis and also associated with down-regulation of Notch-1 and nuclear factor-?B (NF-?B). Taken together, we conclude that the down-regulation of Notch-1 by curcumin could be an effective approach, which will cause down-regulation of NF-?B, resulting in the inhibition of cell growth and invasion. These results suggest that antitumor activity of curcumin is mediated through a novel mechanism involving inactivation of Notch-1 and NF-?B signaling pathways.
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