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Find video protocols related to scientific articles indexed in Pubmed.
Nrbf2 protein suppresses autophagy by modulating Atg14L protein-containing Beclin 1-Vps34 complex architecture and reducing intracellular phosphatidylinositol-3 phosphate levels.
J. Biol. Chem.
PUBLISHED: 08-01-2014
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Autophagy is a tightly regulated lysosomal degradation pathway for maintaining cellular homeostasis and responding to stresses. Beclin 1 and its interacting proteins, including the class III phosphatidylinositol-3 kinase Vps34, play crucial roles in autophagy regulation in mammals. We identified nuclear receptor binding factor 2 (Nrbf2) as a Beclin 1-interacting protein from Becn1(-/-);Becn1-EGFP/+ mouse liver and brain. We also found that Nrbf2-Beclin 1 interaction required the N terminus of Nrbf2. We next used the human retinal pigment epithelial cell line RPE-1 as a model system and showed that transiently knocking down Nrbf2 by siRNA increased autophagic flux under both nutrient-rich and starvation conditions. To investigate the mechanism by which Nrbf2 regulates autophagy, we demonstrated that Nrbf2 interacted and colocalized with Atg14L, suggesting that Nrbf2 is a component of the Atg14L-containing Beclin 1-Vps34 complex. Moreover, ectopically expressed Nrbf2 formed cytosolic puncta that were positive for isolation membrane markers. These results suggest that Nrbf2 is involved in autophagosome biogenesis. Furthermore, we showed that Nrbf2 deficiency led to increased intracellular phosphatidylinositol-3 phosphate levels and diminished Atg14L-Vps34/Vps15 interactions, suggesting that Nrbf2-mediated Atg14L-Vps34/Vps15 interactions likely inhibit Vps34 activity. Therefore, we propose that Nrbf2 may interact with the Atg14L-containing Beclin 1-Vps34 protein complex to modulate protein-protein interactions within the complex, leading to suppression of Vps34 activity, autophagosome biogenesis, and autophagic flux. This work reveals a novel aspect of the intricate mechanism for the Beclin 1-Vps34 protein-protein interaction network to achieve precise control of autophagy.
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Nuclear factor of activated T-cells 5 increases intestinal goblet cell differentiation through an mTOR/Notch signaling pathway.
Mol. Biol. Cell
PUBLISHED: 07-23-2014
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The intestinal mucosa undergoes a continual process of proliferation, differentiation, and apoptosis that is regulated by multiple signaling pathways. Previously, we have shown that the nuclear factor of activated T-cells 5 (NFAT5) is involved in the regulation of intestinal enterocyte differentiation. Here we show that treatment with sodium chloride (NaCl), which activates NFAT5 signaling, increased mTORC1 repressor regulated in development and DNA damage response 1 (REDD1) protein expression and inhibited mTOR signaling; these alterations were attenuated by knockdown of NFAT5. Knockdown of NFAT5 activated mammalian target of rapamycin (mTOR) signaling and significantly inhibited REDD1 mRNA expression and protein expression. Consistently, overexpression of NFAT5 increased REDD1 expression. In addition, knockdown of REDD1 activated mTOR and Notch signaling, whereas treatment with mTOR inhibitor rapamycin repressed Notch signaling and increased the expression of the goblet cell differentiation marker mucin 2 (MUC2). Moreover, knockdown of NFAT5 activated Notch signaling and decreased MUC2 expression, while overexpression of NFAT5 inhibited Notch signaling and increased MUC2 expression. Our results demonstrate a role for NFAT5 in the regulation of mTOR signaling in intestinal cells. Importantly, these data suggest that NFAT5 participates in the regulation of intestinal homeostasis via the suppression of mTORC1/Notch signaling pathway.
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Predicting the likelihood of an isocitrate dehydrogenase 1 or 2 mutation in diagnoses of infiltrative glioma.
Neuro-oncology
PUBLISHED: 05-23-2014
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Several variables are associated with the likelihood of isocitrate dehydrogenase 1 or 2 (IDH1/2) mutation in gliomas, though no guidelines yet exist for when testing is warranted, especially when an R132H IDH1 immunostain is negative.
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Neurotensin, a novel target of Wnt/?-catenin pathway, promotes growth of neuroendocrine tumor cells.
Int. J. Cancer
PUBLISHED: 05-16-2014
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Wnt/?-catenin signaling plays a pivotal role in regulating cell growth and differentiation by activation of the ?-catenin/T-cell factor (TCF) complex and subsequent regulation of a set of target genes that have one or more TCF-binding elements (TBEs). Hyperactivation of this pathway has been implicated in numerous malignancies including human neuroendocrine tumors (NETs). Neurotensin (NT), an intestinal hormone, induces proliferation of several gastrointestinal (GI) cancers including cancers of the pancreas and colon. Here, we analyzed the human NT promoter in silico and found at least four consensus TBEs within the proximal promoter region. Using a combination of ChIP and luciferase reporter assays, we identified one TBE (located ?900 bp proximal from the transcription start site) that was immunoprecipitated efficiently by TCF4-targeting antibody; mutation of this site attenuated the responsiveness to ?-catenin. We also confirmed that the promoter activity and the mRNA and protein expression levels of NT were increased by various Wnt pathway activators and decreased by Wnt inhibitors in NET cell lines BON and QGP-1, which express and secrete NT. Similarly, the intracellular content and secretion of NT were induced by Wnt3a in these cells. Finally, inhibition of NT signaling suppressed cell proliferation and anchorage-independent growth and decreased expression levels of growth-related proteins in NET cells. Our results indicate that NT is a direct target of the Wnt/?-catenin pathway and may be a mediator for NET cell growth.
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Impact of adding the multikinase inhibitor sorafenib to endocrine therapy in metastatic estrogen receptor-positive breast cancer.
Future Oncol
PUBLISHED: 05-16-2014
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? Background: Targeting growth factor and survival pathways may delay endocrine-resistance in estrogen receptor-positive breast cancer. Materials & methods: A pilot Phase II study adding sorafenib to endocrine therapy in 11 patients with metastatic estrogen receptor-positive breast cancer was conducted. Primary end point was response by RECIST after 3 months of sorafenib. Secondary end points included safety, time to progression and biomarker modulation. The study closed early owing to slow accrual. Results: Eight out of 11 patients had progressive disease on study entry and three had stable disease. Of the ten evaluable patients, seven experienced stable disease (70%) and three experienced progressive diseas (30%), with a median time to progression of 6.1 months (8.4 months in the seven patients on tamoxifen). The serum samples demonstrated a significant reduction in VEGF receptor 2 and PDGF receptor-?. Microarray analysis identified 32 suppressed genes, no induced genes and 29 enriched Kyoto Encyclopedia of Genes and Genomes pathways. Conclusion: The strategy of adding a targeted agent to endocrine therapy upon resistance may be worthwhile testing in larger studies.
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Cancer cell-associated fatty acid synthase activates endothelial cells and promotes angiogenesis in colorectal cancer.
Carcinogenesis
PUBLISHED: 02-07-2014
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Upregulation of fatty acid synthase (FASN), a key enzyme of de novo lipogenesis, is associated with metastasis in colorectal cancer (CRC). However, the mechanisms of regulation are unknown. Since angiogenesis is crucial for metastasis, we investigated the role of FASN in the neovascularization of CRC. The effect of FASN on tumor vasculature was studied in orthotopic CRCs, the chick embryo chorioallantoic membrane (CAM) and Matrigel plug models using immunohistochemistry, immunofluorescent staining and confocal microscopy. Cell secretion was evaluated by ELISA and antibody arrays. Proliferation, migration and tubulogenesis of endothelial cells (ECs) were assessed in CRC-EC coculture models. In this study, we found that stable knockdown of FASN decreased microvessel density in HT29 and HCT116 orthotopic CRCs and resulted in 'normalization' of tumor vasculature in both orthotopic and CAM models. Furthermore, FASN regulated secretion of pro- and antiangiogenic factors, including vascular endothelial growth factor-A (VEGF-A). Mechanisms associated with the antiangiogenic activity noted with knockdown of FASN included: downregulation of VEGF(189), upregulation of antiangiogenic isoform VEGF(165b) and a decrease in expression and activity of matrix metalloproteinase-9. Furthermore, conditioned medium from FASN knockdown CRC cells inhibited activation of vascular endothelial growth factor receptor-2 and its downstream signaling and decreased proliferation, migration and tubulogenesis of ECs as compared with control medium. Together, these results suggest that cancer cell-associated FASN regulates tumor vasculature through alteration of the profile of secreted angiogenic factors and regulation of their bioavailability. Inhibition of FASN upstream of VEGF-A and other angiogenic pathways can be a novel therapeutic strategy to prevent or inhibit metastasis in CRC.
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Impact of post-radiation biopsies on development of fistulae in patients with cervical cancer.
Gynecol. Oncol.
PUBLISHED: 01-31-2014
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In the post-radiation patient, late vascular sequelae and fibrosis predispose women to poor tissue healing, such that small tissue injuries could theoretically evolve into much larger ones such as fistulae. We sought to determine if a correlation exists between invasive procedures such as post-treatment biopsies and the subsequent development of gynecologic fistulae.
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Cotargeting the PI3K and RAS pathways for the treatment of neuroendocrine tumors.
Clin. Cancer Res.
PUBLISHED: 01-17-2014
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The precise involvement of the PI3K/mTOR and RAS/MEK pathways in carcinoid tumors is not well defined. Therefore, the purpose of our study was to evaluate the role these pathways play in carcinoid cell proliferation, apoptosis, and secretion and to determine the effects of combined treatment on carcinoid tumor inhibition.
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In Vivo Investigation of Hybrid Paclitaxel Nanocrystals with Dual Fluorescent Probes for Cancer Theranostics.
Pharm. Res.
PUBLISHED: 04-02-2013
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PURPOSE: To develop novel hybrid paclitaxel (PTX) nanocrystals, in which bioactivatable (MMPSense® 750 FAST) and near infrared (Flamma Fluor® FPR-648) fluorophores are physically incorporated, and to evaluate their anticancer efficacy and diagnostic properties in breast cancer xenograft murine model. METHODS: The pure and hybrid paclitaxel nanocrystals were prepared by an anti-solvent method, and their physical properties were characterized. The tumor volume change and body weight change were evaluated to assess the treatment efficacy and toxicity. Bioimaging of treated mice was obtained non-invasively in vivo. RESULTS: The released MMPSense molecules from the hybrid nanocrystals were activated by matrix metalloproteinases (MMPs) in vivo, similarly to the free MMPSense, demonstrating its ability to monitor cancer progression. Concurrently, the entrapped FPR-648 was imaged at a different wavelength. Furthermore, when administered at 20 mg/kg, the nanocrystal formulations exerted comparable efficacy as Taxol®, but with decreased toxicity. CONCLUSIONS: Hybrid nanocrystals that physically integrated two fluorophores were successfully prepared from solution. Hybrid nanocrystals were shown not only exerting antitumor activity, but also demonstrating the potential of multi-modular bioimaging for diagnostics.
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Biodistribution and bioimaging studies of hybrid paclitaxel nanocrystals: lessons learned of the EPR effect and image-guided drug delivery.
J Control Release
PUBLISHED: 03-01-2013
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Paclitaxel (PTX) nanocrystals (200 nm) were produced by crystallization from a solution. Antitumor efficacy and toxicity were examined through a survival study in a human HT-29 colon cancer xenograft murine model. The antitumor activity of the nanocrystal treatments was comparable with that by the conventional solubilization formulation (Taxol®), but yielded less toxicity as indicated by the result of a survival study. Tritium-labeled PTX nanocrystals were further produced with a near infrared (NIR) fluorescent dye physically integrated in the crystal lattice. Biodistribution and tumor accumulation of the tritium-labeled PTX nanocrystals were determined immediately after intravenous administration and up to 48 h by scintillation counting. Whole-body optical imaging of animals was concurrently carried out; fluorescent intensities were also measured from excised tumors and major organs of euthanized animals. It was found that drug accumulation in the tumor was less than 1% of 20mg/kg intravenous dose. Qualitatively correlation was identified between the biodistribution determined by using tritium-labeled particles and that using optical imaging, but quantitative divergence existed. The divergent results suggest possible ways to improve the design of hybrid nanocrystals for cancer therapy and diagnosis. The study also raises questions of the general role of the enhanced permeability and retention (EPR) effect in tumor targeting and the effectiveness of bioimaging, specifically for theranostics, in tracking drug distribution and pharmacokinetics.
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Deregulation of Wnt/?-catenin signaling through genetic or epigenetic alterations in human neuroendocrine tumors.
Carcinogenesis
PUBLISHED: 01-25-2013
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Carcinoid tumors are rare neuroendocrine tumors (NETs) that are increasing in incidence. Mutation and altered expression of Wnt/?-catenin signaling components have been described in many tumors but have not been well-studied in NETs. Here, we observed accumulation of ?-catenin in the cytoplasm and/or nucleus in 25% of clinical NET tissues. By mutational analysis, the mutations of ?-catenin (I35S) and APC (E1317Q, T1493T) were identified in NET cells and the tissues. Expression of representative Wnt inhibitors was absent or markedly decreased in BON, a human pancreatic carcinoid cell line; treatment with 5-aza-2-deoxycytidine (5-aza-CdR) increased expression levels of the Wnt inhibitors. Methylation analyses demonstrated that CpG islands of SFRP-1 and Axin-2 were methylated, whereas the promoters of DKK-1, DKK-3 and WIF-1 were unmethylated in four NET cells. Aberrant methylation of SFRP-1 was particularly observed in most of clinical NET tissues. In addition, the repression of these unmethylated genes was associated with histone H3 lysine 9 dimethylation (H3K9me2) in BON cells. Together, 5-aza-CdR treatment inhibited cell proliferation and decreased the protein levels of H3K9me2 and G9a. Moreover, a novel G9a inhibitor, UNC0638, suppressed BON cell proliferation through inhibition of Wnt/?-catenin pathway. Overexpression of the inhibitory genes, particularly SFRP-1 and WIF-1 in BON cells, resulted in suppression of anchorage-independent growth and inhibition of tumor growth in mice. Our findings suggest that aberrant Wnt/?-catenin signaling, through either mutations or epigenetic silencing of Wnt antagonists, contributes to the pathogenesis and growth of NETs and have important clinical implications for the prognosis and treatment of NETs.
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A phase I study using bortezomib with weekly idarubicin for treatment of elderly patients with acute myeloid leukemia.
Leuk. Res.
PUBLISHED: 01-09-2013
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We report the results of a phase I study with four dose levels of bortezomib in combination with idarubicin. Eligible patients were newly diagnosed with acute myeloid leukemia (AML) age ?60 years, or any adult with relapsed AML. Bortezomib was given twice weekly at 0.8, 1.0, or 1.2 mg/m(2) with once weekly idarubicin 10 mg/m(2) for four weeks. Twenty patients were treated: 13 newly diagnosed (median age 68, range 61-83) and 7 relapsed (median age 58, range 40-77). Prior myelodysplastic syndrome (MDS) was documented in 10/13 (77%) newly diagnosed and 1/7 (14%) relapsed patients; the three newly diagnosed patients without prior MDS had dyspoietic morphology. Two dose-limiting toxicities occurred at the initial dose level (bortezomib 0.8 mg/m(2) and idarubicin 10 mg/m(2)); idarubicin was reduced to 8 mg/m(2) without observing subsequent dose-limiting toxicities. The maximum tolerated dose in this study was bortezomib 1.2 mg/m(2) and idarubicin 8 mg/m(2). Common adverse events included: neutropenic fever, infections, constitutional symptoms, and gastrointestinal symptoms. No subjects experienced neurotoxicity. Most patients demonstrated hematologic response as evidenced by decreased circulating blasts. Four patients (20%) achieved complete remission. There was one treatment-related death. The combination of bortezomib and idarubicin in this mostly poor-risk, older AML group was well tolerated and did not result in high mortality. This trial was registered at www.clinicaltrials.gov as #NCT00382954.
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A survey of the barriers associated with academic-based cancer research commercialization.
PLoS ONE
PUBLISHED: 01-01-2013
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Commercialization within the academic setting is associated with many challenges and barriers. Previous studies investigating these challenges/barriers have, in general, broadly focused on multiple disciplines and, oftentimes, several institutions simultaneously. The goal of the study presented here was to analyze a range of barriers that may be broadly associated with commercializing academic-based cancer research. This goal was addressed via a study of the barriers associated with cancer research commercialization at the University of Kentucky (UK). To this end, a research instrument in the form of an electronic survey was developed. General demographic information was collected on study participants and two research questions were addressed: 1) What are the general barriers inhibiting cancer research commercialization at UK? and 2) Would mitigation of the barriers potentially enhance faculty engagement in commercialization activities? Descriptive and statistical analysis of the data reveal that multiple barriers likely inhibit cancer research commercialization at UK with expense, time, infrastructure, and lack of industry partnerships being among the most commonly cited factors. The potential alleviation of these factors in addition to revised University policies/procedures, risk mitigation, more emphasis on commercialization by academia research field, and increased information on how to commercialize significantly correlated with the potential for increased commercialization activity. Furthermore, multivariate logistic regression modeling demonstrated that research commercialization would incrementally increase as barriers to the process are removed and that PhD-holding respondents and respondents in commercialization-supportive research fields would be more likely to commercialize their research upon barrier removal. Overall, as with other disciplines, these data suggest that for innovations derived from academic cancer-research to move more effectively and efficiently into the marketplace, university administrators and external agents, such as policymakers, need to address what are well-documented and defined issues.
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Regulation of the potential marker for intestinal cells, Bmi1, by ?-catenin and the zinc finger protein KLF4: implications for colon cancer.
J. Biol. Chem.
PUBLISHED: 12-14-2011
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B lymphoma Mo-MLV insertion region 1 (Bmi1) is a Polycomb Group (PcG) protein important in gene silencing. It is a component of Polycomb Repressive Complex 1 (PRC1), which is required to maintain the transcriptionally repressive state of many genes. Bmi1 was initially identified as an oncogene that regulates cell proliferation and transformation, and is important in hematopoiesis and the development of nervous systems. Recently, it was reported that Bmi1 is a potential marker for intestinal stem cells. Because Wnt signaling plays a key role in intestinal stem cells, we analyzed the effects of Wnt signaling on Bmi1 expression. We found that Wnt signaling indeed regulates the expression of Bmi1 in colon cancer cells. In addition, the expression of Bmi1 in human colon cancers is significantly associated with nuclear ?-catenin, a hallmark for the activated Wnt signaling. Krüppel-like factor 4 (KLF4) is a zinc finger protein highly expressed in the gut and skin. We recently found that KLF4 cross-talks with Wnt/?-catenin in regulating intestinal homeostasis. We demonstrated that KLF4 directly inhibits the expression of Bmi1 in colon cancer cells. We also found that Bmi1 regulates histone ubiquitination and is required for colon cancer proliferation in vitro and in vivo. Our findings further suggest that Bmi1 is an attractive target for cancer therapeutics.
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Dicer-mediated upregulation of BCRP confers tamoxifen resistance in human breast cancer cells.
Clin. Cancer Res.
PUBLISHED: 08-30-2011
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Tamoxifen (Tam) is the most prescribed hormonal agent for treatment of estrogen receptor ? (ER?)-positive breast cancer patients. Using microarray analysis, we observed that metastatic breast tumors resistant to Tam therapy had elevated levels of Dicer.
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A phase II neoadjuvant trial of anastrozole, fulvestrant, and gefitinib in patients with newly diagnosed estrogen receptor positive breast cancer.
Breast Cancer Res. Treat.
PUBLISHED: 07-07-2011
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Endocrine therapy in patients with breast cancer can be limited by the problem of resistance. Preclinical studies suggest that complete blockade of the estrogen receptor (ER) combined with inhibition of the epidermal growth factor receptor can overcome endocrine resistance. We tested this hypothesis in a phase II neoadjuvant trial of anastrozole and fulvestrant combined with gefitinib in postmenopausal women with newly diagnosed ER-positive breast cancer. After a baseline tumor core biopsy, patients were randomized to receive anastrozole and fulvestrant or anastrozole, fulvestrant, and gefitinib (AFG) for 3 weeks. After a second biopsy at 3 weeks, all patients received AFG for 4 months and surgery was done if the tumor was operable. The primary endpoint was best clinical response by RECIST criteria and secondary endpoints were toxicity and change in biomarkers. The study closed after 15 patients were enrolled because of slow accrual. Median patient age was 67 years and median clinical tumor size was 7 cm. Four patients had metastatic disease present. Three patients withdrew before response was assessed. In the remaining 12 patients, there were two complete clinical responses (17%), three partial responses (25%), five had stable disease (41%), and two (17%) had progressive disease. Most common adverse events were rash in four patients, diarrhea in four, joint symptoms in three, and abnormal liver function tests in three. There were no grade 4 toxicities and all toxicities were reversible. At 3 weeks, cell proliferation as measured by Ki-67 was significantly reduced in the AFG group (P value = 0.01), with a parallel reduction in the expression of the Cyclin D1 (P value = 0.02). RNA microarray data showed a corresponding decrease in the expression of cell cycle genes. These results suggest that AFG was an effective neoadjuvant therapy and consistently reduced proliferation in ER-positive tumors.
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Case-matching analysis of head and neck squamous cell carcinoma in racial and ethnic minorities in the United States--possible role for human papillomavirus in survival disparities.
Head Neck
PUBLISHED: 05-20-2011
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Several studies have documented disparities in head and neck cancer outcomes for black patients in the United States. Recent studies have found that differences in oropharyngeal tumor human papillomavirus (HPV) status may be a cause of this disparity.
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The effect of PTEN on serotonin synthesis and secretion from the carcinoid cell line BON.
Anticancer Res.
PUBLISHED: 04-22-2011
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Carcinoid tumors are associated with the carcinoid syndrome, a set of symptoms resulting from the peptide and amine products, including serotonin, secreted from the cancer cells. The purpose of this study was to investigate the relationship between the phosphatidylinositol-3-kinase/protein kinase B (PI3K/Akt) inhibitor PTEN (phosphatase and tensin homolog deleted on chromosome ten) and serotonin synthesis and secretion in the carcinoid cancer cell line BON.
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mTORC1 inhibition increases neurotensin secretion and gene expression through activation of the MEK/ERK/c-Jun pathway in the human endocrine cell line BON.
Am. J. Physiol., Cell Physiol.
PUBLISHED: 04-20-2011
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The mammalian target of rapamycin (mTOR) signaling exists in two complexes: mTORC1 and mTORC2. Neurotensin (NT), an intestinal hormone secreted by enteroendocrine (N) cells in the small bowel, has important physiological effects in the gastrointestinal tract. The human endocrine cell line BON abundantly expresses the NT gene and synthesizes and secretes NT in a manner analogous to that of N cells. Here, we demonstrate that the inhibition of mTORC1 by rapamycin (mTORC1 inhibitor), torin1 (both mTORC1 and mTORC2 inhibitor) or short hairpin RNA-mediated knockdown of mTOR, regulatory associated protein of mTOR (RAPTOR), and p70 S6 kinase (p70S6K) increased basal NT release via upregulating NT gene expression in BON cells. c-Jun activity was increased by rapamycin or torin1 or p70S6K knockdown. c-Jun overexpression dramatically increased NT promoter activity, which was blocked by PD98059, an mitogen-activated protein kinase kinase (MEK) inhibitor. Furthermore, overexpression of MEK1 or extracellular signal-regulated kinase 1 (ERK1) increased c-Jun expression and NT promoter activity. More importantly, PD98059 blocked rapamycin- or torin1-enhanced NT secretion. Consistently, rapamycin and torin1 also increased NT gene expression in Hep3B cells, a human hepatoma cell line that, similar to BON, expresses high levels of NT. Phosphorylation of c-Jun and ERK1/2 was also increased by rapamycin and torin1 in Hep3B cells. Finally, we showed activation of mTOR in BON cells treated with amino acids, high glucose, or serum and, concurrently, the attenuation of ERK1/2 and c-Jun phosphorylation and NT secretion. Together, mTORC1, as a nutrient sensor, negatively regulates NT secretion via the MEK/ERK/c-Jun signaling pathway. Our results identify a physiological link between mTORC1 and MEK/ERK signaling in controlling intestinal hormone gene expression and secretion.
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mTORC1 and mTORC2 regulate EMT, motility, and metastasis of colorectal cancer via RhoA and Rac1 signaling pathways.
Cancer Res.
PUBLISHED: 03-23-2011
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Activation of phosphoinositide 3-kinase (PI3K)/Akt signaling is associated with growth and progression of colorectal cancer (CRC). We have previously shown that the mTOR kinase, a downstream effector of PI3K/Akt signaling, regulates tumorigenesis of CRC. However, the contribution of mTOR and its interaction partners toward regulating CRC progression and metastasis remains poorly understood. We found that increased expression of mTOR, Raptor, and Rictor mRNA was noted with advanced stages of CRC, suggesting that mTOR signaling may be associated with CRC progression and metastasis. mTOR, Raptor, and Rictor protein levels were also significantly elevated in primary CRCs (stage IV) and their matched distant metastases compared with normal colon. Inhibition of mTOR signaling, using rapamycin or stable inhibition of mTORC1 (Raptor) and mTORC2 (Rictor), attenuated migration and invasion of CRCs. Furthermore, knockdown of mTORC1 and mTORC2 induced a mesenchymal-epithelial transition (MET) and enhanced chemosensitivity of CRCs to oxaliplatin. We observed increased cell-cell contact and decreased actin cytoskeletal remodeling concomitant with decreased activation of the small GTPases, RhoA and Rac1, upon inhibition of both mTORC1 and mTORC2. Finally, establishment of CRC metastasis in vivo was completely abolished with targeted inhibition of mTORC1 and mTORC2 irrespective of the site of colonization. Our findings support a role for elevated mTORC1 and mTORC2 activity in regulating epithelial-mesenchymal transition (EMT), motility, and metastasis of CRCs via RhoA and Rac1 signaling. These findings provide the rationale for including mTOR kinase inhibitors, which inhibit both mTORC1 and mTORC2, as part of the therapeutic regimen for CRC patients.
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NFATc1 regulation of TRAIL expression in human intestinal cells.
PLoS ONE
PUBLISHED: 02-08-2011
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TNF-related apoptosis-inducing ligand (TRAIL; Apo2) has been shown to promote intestinal cell differentiation. Nuclear factor of activated T cells (NFAT) participates in the regulation of a variety of cellular processes, including differentiation. Here, we examined the role of NFAT in the regulation of TRAIL in human intestinal cells. Treatment with a combination of phorbol 12-myristate 13-acetate (PMA) plus the calcium ionophore A23187 (Io) increased NFAT activation and TRAIL expression; pretreatment with the calcineurin inhibitor cyclosporine A (CsA), an antagonist of NFAT signaling, diminished NFAT activation and TRAIL induction. In addition, knockdown of NFATc1, NFATc2, NFATc3, and NFATc4 blocked PMA/Io increased TRAIL protein expression. Expression of NFATc1 activated TRAIL promoter activity and increased TRAIL mRNA and protein expression. Deletion of NFAT binding sites from the TRAIL promoter did not significantly abrogate NFATc1-increased TRAIL promoter activity, suggesting an indirect regulation of TRAIL expression by NFAT activation. Knockdown of NFATc1 increased Sp1 transcription factor binding to the TRAIL promoter and, importantly, inhibition of Sp1, by chemical inhibition or RNA interference, increased TRAIL expression. These studies identify a novel mechanism for TRAIL regulation by which activation of NFATc1 increases TRAIL expression through negative regulation of Sp1 binding to the TRAIL promoter.
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Characterization of promoter elements regulating the expression of the human neurotensin/neuromedin N gene.
J. Biol. Chem.
PUBLISHED: 10-28-2010
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Expression of the gene encoding neurotensin/neuromedin N (NT/N) is mostly limited to the brain and specialized enteroendocrine N cells in the distal small intestine. We have identified key regulatory elements in the promoter region that are involved in human NT/N (hNT/N) gene expression in the novel human endocrine cell line, BON, which resembles intestinal N cells in several important aspects including NT/N precursor protein processing, ratios of different NT/N mRNA isoforms, and high levels of constitutive expression of the NT/N gene. In this study, we demonstrated multiple cis-regulatory elements including a proximal region containing a cAMP-responsive element (CRE)/AP-1-like element that binds both the AP-1 and CRE-binding protein (CREB)/ATF proteins (c-Jun, ATF-1, ATF-2, JunD, and CREB). Similar to the rat NT/N gene, this region is critical for constitutive hNT/N gene expression. Moreover, we identified a novel region that binds the orphan hormone receptor, NR2F2. We have demonstrated that the C terminus of NR2F2 strongly represses hNT/N transcription, whereas an N-terminal domain antagonizes this repressive effect. Regulation of NT/N expression by NR2F2 may have important consequences for lipid metabolism. We speculate that a complex interplay between the proximal CRE/AP-1-like motif and NR2F2 binding region exists to regulate hNT/N expression, which is critical for the high level of constitutive expression of NT/N in enteroendocrine cells. Finally, the BON cell line provides a unique model to characterize the factors regulating expression of the hNT/N gene and to better understand the mechanisms responsible for terminal differentiation of the N cell lineage in the gut.
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Clinicopathological predictors of lymphatic metastasis in HNSCC: implications for molecular mechanisms of metastatic disease.
J. Exp. Ther. Oncol.
PUBLISHED: 08-26-2010
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Lymphatic metastasis is associated with up to a 50% decrease in survival, yet the molecular mechanisms driving their establishment remain poorly understood. This study assessed clinicopathological characteristics correlated to nodal metastasis among patients with head and neck squamous cell carcinoma for the identification of pathways on which to focus molecular studies. Pathology records were queried for cases diagnosed with invasive squamous cell cancer of the upper aerodigestive tract between 1993 and 2003. Charts and pathology reports were scored for 16 characteristics. The univariate association of each variable with lymph node status was assessed. Based on the univariate analysis, a multiple logistic regression model was developed to assess the simultaneous association of variables with lymph node status. Of the 644 cases identified, 234 had a surgical specimen analyzed. All variables were scored for 185 of the 234 cases. Multivariate stepwise regression analysis identified clinical stage (p = 0.0269), pathologic stage (p = 0.0162), grade (p = 0.0094), lymphovascular invasion (p = 0.0393), and family history of cancer (p = 0.0079) as independently predictive of lymphatic metastases. Our study confirms that grade, pathologic stage, clinical stage, and lymphovascular invasion are predictors of regional metastasis. These correlations suggest that studying the molecular mechanisms of differentiation, interstitial pressure at the primary tumor site, and peritumoral lymphangiogenesis may provide insight into lymphatic metastasis. Additionally, we identified family history of cancer as a new predictor of lymphatic metastasis. Thus, genetic analysis of families with cancer, irrespective of type, may identify genes important for regional metastasis.
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Novel expression patterns of PI3K/Akt/mTOR signaling pathway components in colorectal cancer.
J. Am. Coll. Surg.
PUBLISHED: 04-28-2010
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The phosphatidylinositol 3-kinase/Akt/mammalian target of rapamycin (PI3K/Akt/mTOR) pathway plays a critical role in the growth and progression of colorectal cancer (CRC). The purpose of our study was 2-fold: (1) to determine the expression levels of several key components of this pathway, including p85alpha, Akt1, Akt2, p-mTOR(Ser2448), and p-p70S6K(Thr389) in CRCs; and (2) to correlate the expression of these proteins with cancer stage and location (left versus right side).
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Epidermal growth factor receptor expression in breast cancer association with biologic phenotype and clinical outcomes.
Cancer
PUBLISHED: 01-19-2010
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Epidermal growth factor receptor (EGFR) expression is associated with aggressive phenotypes in preclinical breast cancer models, but in clinical studies, EGFR has been inconsistently linked to poor outcome. We hypothesized that EGFR expression in human breast tumors, when centrally and uniformly assessed, is associated with an aggressive phenotype and resistance to systemic therapy.
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Nuclear IRS-1 predicts tamoxifen response in patients with early breast cancer.
Breast Cancer Res. Treat.
PUBLISHED: 10-29-2009
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Insulin receptor substrate-1 (IRS-1) is a cytoplasmic scaffolding protein that is phosphorylated by insulin-like growth factor-I receptor and recruits downstream effectors. Recent evidence suggests that IRS-1 has a nuclear localization and function. Here we investigated whether nuclear and cytoplasmic IRS-1 levels are associated with clinico-pathological characteristics and clinical outcome in breast cancer patients. Tissue microarrays from 1,097 patients with stage I-II breast cancer were stained by immunohistochemistry for IRS-1. Nuclear and cytoplasmic IRS-1 were scored separately according to the Allred score. Nuclear IRS-1 showed a positive association with estrogen receptor (ER) (r = 0.09, P = 0.003) and progesterone receptor (PR) (r = 0.08, P = 0.008) status and a negative correlation with lymph node involvement (r = -0.10, P = 0.001). Cytoplasmic IRS-1 did not correlate with ER or PR but showed a positive correlation with tumor size (r = 0.10, P = 0.001) and S-phase fraction (r = 0.16, P < 0.001). In univariate analysis, tamoxifen-treated patients with tumors showing positive nuclear IRS-1 had a better recurrence-free survival (RFS) (P = 0.009) and overall survival (OS) (P = 0.0007), while no association was shown between cytoplasmic IRS-1 and RFS or OS in the same group of patients. In multivariate analysis of patients receiving tamoxifen, negative nuclear IRS-1 showed a significantly reduced RFS (P = 0.046) and OS (P = 0.018). Combining both PR and nuclear IRS-1, tamoxifen-treated patients with PR+/IRS-1+ tumors had a better RFS (P = 0.0003) and OS (P < 0.0001) when compared with patients with PR-/IRS-1- tumors. In conclusion, nuclear IRS-1 may be a useful marker to predict tamoxifen response in patients with early breast cancer, particularly when assessed in combination with PR.
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Use of error grid analysis to evaluate acceptability of a point of care prothrombin time meter.
Clin. Chim. Acta
PUBLISHED: 05-20-2009
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Statistical methods (linear regression, correlation analysis, etc.) are frequently employed in comparing methods in the central laboratory (CL). Assessing acceptability of point of care testing (POCT) equipment, however, is more difficult because statistically significant biases may not have an impact on clinical care. We showed how error grid (EG) analysis can be used to evaluate POCT PT INR with the CL.
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Enhancing the in vivo expansion of adoptively transferred EBV-specific CTL with lymphodepleting CD45 monoclonal antibodies in NPC patients.
Blood
PUBLISHED: 04-14-2009
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Treatment of Epstein-Barr virus (EBV)-positive nasopharyngeal carcinoma (NPC) with EBV-specific cytotoxic T cells (EBV-specific CTL) has been promising, producing clinical responses. However, infused EBV-specific CTL did not expand in vivo, likely limiting their antitumor activity. Lymphodepleting patients with chemotherapy before T-cell transfer enhances in vivo T-cell expansion, but results in nonspecific destruction of the resident immune system and can have significant toxicity. To evaluate if monoclonal antibodies (mAbs) can produce a more selective lymphodepletion, we conducted a clinical study in which NPC patients received a pair of lymphodepleting mAbs targeted to the CD45 antigen (CD45 mAbs) before EBV-specific CTL infusion. Eight patients with recurrent NPC received CD45 mAbs followed by escalating doses of autologous EBV-specific CTL. Infusion of CD45 mAbs resulted in transient lymphopenia in all patients and an increase in interleukin-15 (IL-15) levels in 6 out 8 patients. All patients had an increase in their peripheral blood frequency of EBV-specific T cells after CTL infusion. Three patients with a persistent increase had clinical benefits including 1 complete response (> 24 months) and 2 with stable disease (for 12 and 15 months). Lymphodepleting mAbs prior CTL transfer may represent an alternative to chemotherapy to enhance expansion of infused CTL. This study is registered at (http://www.clinialtrials.gov) as NCT00608257.
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Visualizing hepatitis C virus infections in human liver by two-photon microscopy.
Gastroenterology
PUBLISHED: 03-16-2009
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Although hepatitis C virus (HCV) is a common cause of cirrhosis and liver cancer, efforts to understand the pathogenesis of HCV infection have been limited by the low abundance of viral proteins expressed within the liver, which hinders the detection of infected cells in situ. This study evaluated the ability of advanced optical imaging techniques to determine the extent and distribution of HCV-infected cells within the liver.
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A prognostic model of early breast cancer relapse after standard adjuvant therapy and comparison with metastatic disease on initial presentation.
Breast Cancer Res. Treat.
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Breast cancer can metastasize at any time during its course, but timing of systemic relapse cannot be predicted by traditional TNM staging. Characteristics of distant recurrence within the first 3 years of diagnosis may identify a group of patients who could benefit from novel strategies to prevent systemic relapse. Of 1,089 patients with breast cancer treated at our institution between January 2007 and May 2011, we identified 76 with de novo metastases (on presentation) and 40 with systemic relapse after a median follow up of 2.2 years. Compared to relapse, de novo metastatic disease was more likely to be grade 1 or 2 (43.1 vs. 18.4 %, p = 0.032), estrogen receptor (ER) positive (69.7 vs. 47.5 %, p = 0.019), progesterone receptor (PgR) positive (56.6 vs. 32.5 %, p = 0.014), and HER2-positive (27.5 vs. 10.3 %, p = 0.035). In the 815 patients with stage I-III disease who were at risk of systemic relapse, univariate analyses were performed for age, tumor size, grade, ER, PgR, HER2, lymph nodes, and TNM stage. A multivariate Cox regression model was built using step-wise model selection and identified 4 covariates that were significantly associated with risk of early relapse: stage-III (p < 0.001), grade-III (p = 0.002), PgR-negative status (p = 0.014), and HER2-negative status (p = 0.033). A risk-score was developed based on the linear combination of these covariates and time-dependent predictive curves were used to evaluate the predictive accuracy of the proposed risk-score. The highest risk-score group had a 1, 2, and 3-year relapse probabilities of 11.5, 41.2, and 52.5 %, respectively. The corresponding 1, 2, and 3-year relapse probabilities for the overall population were 1.2, 4.4, and 6.3 %, respectively. Our proposed model can be used to select patients at high-risk of early relapse who could benefit from enrollment on clinical trials with novel therapies designed for this group.
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PI3K p110?/Akt signaling negatively regulates secretion of the intestinal peptide neurotensin through interference of granule transport.
Mol. Endocrinol.
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Neurotensin (NT), an intestinal peptide secreted from N cells in the small bowel, regulates a variety of physiological functions of the gastrointestinal tract, including secretion, gut motility, and intestinal growth. The class IA phosphatidylinositol 3-kinase (PI3K) family, which comprised of p110 catalytic (?, ? and ?) and p85 regulatory subunits, has been implicated in the regulation of hormone secretion from endocrine cells. However, the underlying mechanisms remain poorly understood. In particular, the role of PI3K in intestinal peptide secretion is not known. Here, we show that PI3K catalytic subunit, p110?, negatively regulates NT secretion in vitro and in vivo. We demonstrate that inhibition of p110?, but not p110?, induces NT release in BON, a human endocrine cell line, which expresses NT mRNA and produces NT peptide in a manner analogous to N cells, and QGP-1, a pancreatic endocrine cell line that produces NT peptide. In contrast, overexpression of p110? decreases NT secretion. Consistently, p110?-inhibition increases plasma NT levels in mice. To further delineate the mechanisms contributing to this effect, we demonstrate that inhibition of p110? increases NT granule trafficking by up-regulating ?-tubulin acetylation; NT secretion is prevented by overexpression of HDAC6, an ?-tubulin deacetylase. Moreover, ras-related protein Rab27A (a small G protein) and kinase D-interacting substrate of 220 kDa (Kidins220), which are associated with NT granules, play a negative and positive role, respectively, in p110?-inhibition-induced NT secretion. Our findings identify the critical role and novel mechanisms for the PI3K signaling pathway in the control of intestinal hormone granule transport and release.
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Nuclear factor of activated T-cell c3 inhibition of mammalian target of rapamycin signaling through induction of regulated in development and DNA damage response 1 in human intestinal cells.
Mol. Biol. Cell
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The nuclear factor of activated T-cell (NFAT) proteins are a family of transcription factors (NFATc1-c4) involved in the regulation of cell differentiation. We identified REDD1, a negative regulator of mammalian target of rapamycin (mTOR) through the tuberous sclerosis complex (TSC1/2 complex), as a new molecular target of NFATc3. We show that treatment with a combination of phorbol 12-myristate 13-acetate (PMA) plus ionophore A23187 (Io), which induces NFAT activation, increased REDD1 mRNA and protein expression and inhibited mTOR signaling; pretreatment with the calcineurin inhibitor cyclosporin A (CsA), an antagonist of NFAT signaling, decreased REDD1 induction and mTOR inhibition. Knockdown of NFATc3, not NFATc1, NFATc2, or NFATc4, attenuated PMA/Io-induced REDD1 expression. Treatment with PMA/Io increased REDD1 promoter activity and increased NFATc3 binding to the REDD1 promoter. Overexpression of NFATc3 increased REDD1 mRNA and protein expression and increased PMA/Io-mediated REDD1 promoter activity. Treatment with PMA/Io increased expression of the goblet cell differentiation marker MUC2; these changes were attenuated by pretreatment with CsA or knockdown of REDD1 or NFATc3. Overexpression of NFATc3 increased, while knockdown of TSC2 decreased, MUC2 expression. We provide evidence showing NFATc3 inhibits mTOR via induction of REDD1. Our results suggest a role for the NFATc3/REDD1/TSC2 axis in the regulation of intestinal cell differentiation.
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Sorafenib enhances the therapeutic efficacy of rapamycin in colorectal cancers harboring oncogenic KRAS and PIK3CA.
Carcinogenesis
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Activation of phosphatidylinositol 3-kinase (PI3K)/Akt signaling is associated with tumorigenesis and metastasis of colorectal cancer (CRC). The mammalian target of rapamycin (mTOR) kinase, a downstream effector of PI3K/Akt signaling, regulates tumorigenesis and metastasis of CRCs, indicating that mTOR inhibition may have therapeutic potential. Notwithstanding, many cancers, including CRC, demonstrate resistance to the antitumorigenic effects of rapamycin. In this study, we show that inhibition of mTORC1 with rapamycin leads to feedback activation of PI3K/Akt and Ras-MAPK signaling, resulting in cell survival and possible contribution to rapamycin resistance. Combination with the multikinase inhibitor, sorafenib, abrogates rapamycin-induced activation of PI3K/Akt and Ras-MAPK signaling pathways. Combination of rapamycin with sorafenib synergistically inhibits proliferation of CRC cells. CRCs harboring coexistent KRAS and PIK3CA mutations are partially sensitive to either rapamycin or sorafenib monotherapy, but highly sensitive to combination treatment with rapamycin and sorafenib. Combination with sorafenib enhances therapeutic efficacy of rapamycin on induction of apoptosis and inhibition of cell-cycle progression, migration and invasion of CRCs. We demonstrate efficacy and safety of concomitant treatment with rapamycin and sorafenib at inhibiting growth of xenografts from CRC cells with coexistent mutations in KRAS and PIK3CA. The efficacy and tolerability of combined treatment with rapamycin and sorafenib provides rationale for use in treating CRC patients, particularly those with tumors harboring coexistent KRAS and PIK3CA mutations.
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Hedgehog signaling activation in the development of squamous cell carcinoma and adenocarcinoma of esophagus.
Int J Biochem Mol Biol
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Hedgehog (Hh) signaling is frequently activated in human cancer, including esophageal cancer. Most esophageal cancers are diagnosed in the advanced stages, therefore, identifying the very alterations that drive esophageal carcinogenesis may help designing novel strategies to diagnose and treat the disease. Analysis of Hh signaling in precancerous lesions is a critical first step in determining the significance of this pathway for carcinogenesis. Here we report our data on Hh target gene expression in 174 human esophageal specimens [28 esophageal adenocarcinomas (EAC), 19 Barretts esophagus, 103 cases of esophageal squamous cell carcinoma (ESCC), and 24 of squamous dysplastic lesions], and in two rat models of esophageal cancer. We found that 96% of human EAC express Hh target genes. We showed that PTCH1 expression is the most reliable biomarker. In contrast to EAC, only 38% of ESCC express Hh target genes. We found activation of Hh signaling in precancerous lesions of ESCCs and EACs in different degrees (21% and 58% respectively). Expression of Hh target genes is frequently detected in severe squamous dysplasia/ carcinoma in situ (p=0.04) and Barretts esophagus (p=0.01). Unlike EAC, sonic hedgehog (Shh) expression was rare in ESCCs. Consistent with the human specimen data, we found a high percentage of Hh signaling activation in precancerous lesions in rat models. These data indicate that Hh signaling activation is an early molecular event in the development of esophageal cancer, particularly EAC.
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Inhibition of fatty acid synthase attenuates CD44-associated signaling and reduces metastasis in colorectal cancer.
Cancer Res.
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Fatty acid synthase (FASN) and ATP-citrate lyase, key enzymes of de novo lipogenesis, are significantly upregulated and activated in many cancers and portend poor prognosis. Even though the role of lipogenesis in providing proliferative and survival advantages to cancer cells has been described, the impact of aberrant activation of lipogenic enzymes on cancer progression remains unknown. In this study, we found that elevated expression of FASN is associated with advanced stages of colorectal cancer (CRC) and liver metastasis, suggesting that it may play a role in progression of CRC to metastatic disease. Targeted inhibition of lipogenic enzymes abolished expression of CD44, a transmembrane protein associated with metastases in several cancers including CRC. In addition, inhibition of lipogenic enzymes and reduced expression of CD44 attenuated the activation of MET, Akt, FAK, and paxillin, which are known to regulate adhesion, migration, and invasion. These changes were consistent with an observed decrease in migration and adhesion of CRC cells in functional assays and with reorganization of actin cytoskeleton upon FASN inhibition. Despite the modest effect of FASN inhibition on tumor growth in xenografts, attenuation of lipogenesis completely abolished establishment of hepatic metastasis and formation of secondary metastasis. Together, our findings suggest that targeting de novo lipogenesis may be a potential treatment strategy for advanced CRC.
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JoVE Visualize is a tool created to match the last 5 years of PubMed publications to methods in JoVE's video library.

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We use abstracts found on PubMed and match them to JoVE videos to create a list of 10 to 30 related methods videos.

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In developing our video relationships, we compare around 5 million PubMed articles to our library of over 4,500 methods videos. In some cases the language used in the PubMed abstracts makes matching that content to a JoVE video difficult. In other cases, there happens not to be any content in our video library that is relevant to the topic of a given abstract. In these cases, our algorithms are trying their best to display videos with relevant content, which can sometimes result in matched videos with only a slight relation.