MicroRNAs are small non-coding RNA molecules that have been shown to regulate the expression of genes linked to cancer. The relevance of microRNAs in the development, progression and prognosis of prostate cancer is not fully understood. It is also possible that these specific molecules may assist in the recognition of aggressive tumors and the development of new molecular targets. Our study investigated the importance of several microRNAs in cases of prostate cancer from 37 patients that were manually microdissected to obtain pure populations of tumor cells, normal epithelium and adjacent stroma. MicroRNA was extracted for PCR array profiling. Differentially expressed miRNAs for each case were used to compare tumor vs. normal epithelium and tumor-adjacent stroma samples. Loss of 18 miRNAs (e.g.miR-34c, miR-29b, miR-212 and miR-10b) and upregulation of miR-143 and miR-146b were significantly found in all the tumors in comparison with normal epithelium and/or stroma (p? 0.001). A different signature was found in the high grade tumors (Gleason score ? 8) when compared with tumors Gleason score 6. Upregulation of miR-122, miR-335, miR-184, miR-193, miR-34, miR-138, miR-373, miR-9, miR-198, miR-144 and miR-215 and downregulation of miR-96, miR-222, miR-148, miR-92, miR-27, miR-125, miR-126, miR-27 were found in the high grade tumors. MicroRNA profiling in prostate cancer appears to have unique expression patterns in comparison with normal tissue. These differential expressed miRNAs may provide novel diagnostic and prognostic tools that will assist in the recognition of prostate cancers with aggressive behavior.
Background & Aims: In order to understand the role of miRNAs in renal tumorigenesis, we undertook a stepwise approach that included a comprehensive differential miRNA expression analysis for the most common histological subtypes of human renal neoplasms appearing in either sporadic or hereditary forms. We also aimed to test the hypothesis that microRNAs can act as an alternative mechanism of VHL gene inactivation and therefore might be correlated with tumorigenesis in ccRCC. Finally, we wanted to explore whether the well-known hypoxic activation of ccRCC is followed by a specific pattern of miRNA expression.Methods: Tumor and normal adjacent kidney parenchyma from patients with RCC were tested for microRNA expression. Twenty cases of different histologies were used for profiling by PCR miRNA arrays. For validation, a separate cohort of samples used to test specifically miR92a expression and its involvement in VHL gene mRNA silencing. Finally, miR210 as a marker of hypoxia was evaluated. Expression values were correlated with important clinicopathologic features from the patients.Results: We identified unique miRNA expression signatures for each histologic subtype of kidney tumors. Expression values for downregulated miRNAs ranged from 0.3-fold (in VHL-clear cell RCC) up to 0.393 fold (in papillary type II (HLRCC) tumors). For the upregulated miRNAs, fold-changes ranged from 2.1 up to 290-fold. Specific patterns together with type-specific profiles were observed. Twenty-three miRNAs were found to be differentially expressed in both sporadic and VHL-dependent ccRCC. Sporadic clear cell tumors showed a unique pattern of 14-miRNA that were absent from the VHL-dependent tumors. These also showed 15 miRNAs specific to the hereditary type. Common miRNAs to both sporadic and hereditary forms included miR-92a and miR-210. For miR-92a, and a striking inverse correlation with VHL mRNA levels was found. For the hypoxia-regulated miR-210, clear cell tumors showed significantly higher expression levels when compared to tumor of non-clear cell histology (9.90-fold vs. 1.36, p<0.001).Conclusions: microRNA expression seems to be involved in every step of RCC pathogenesis: both as an element for tumor development as well as a consequence of or in response to the initial malignant transformation and part of tumor progression. Our data show consistent disregulation of miRNAs in human kidney cancer, some of which are potentially involved in critical gene silencing in RCC and others that are activated as part of the pathophysiological response in these tumors.
Clear cell renal cell carcinoma (RCC) represents the most common histological subtype of malignant kidney tumors. Based on symptoms alone, clear cell RCC is indistinguishable from other histological classes of RCC unless the tumor is present in the context of an RCC syndrome. Histopathological examination is, therefore, important to accurately identify clear cell RCC. Clear cell RCCs have characteristic morphological criteria; these tumors can be easily identified upon typical presentation, but diagnosis can be challenging when tumor cell pattern is unusual or when availability of tissue samples is limited. In this Review, the clinical, radiological and pathological characteristics of clear cell RCCs are described, as well as the potential tumors that can be confused with clear cell RCC and need to be considered in the differential diagnoses. Finally, the importance of an accurate diagnosis is highlighted in the context of the increasing use of preoperative tissue sampling and the prevalence of clear cell tumors associated with hereditary syndromes, which could have different therapeutic and prognostic implications for patients and their families.
Aims: microRNAs (miRNAs) are a class of small noncoding RNAs that can act as key modulators in tumorigenesis-related genes. Specifically, it has been suggested that miR-21 overexpression plays a role in the development and progression of breast cancer. So far, the role of miRNAs in pregnancy-associated breast cancer (PABC) has not been investigated.Methods and Results: We evaluated miR-21 expression by quantitative RT-PCR in 35 patients, 25 with PABC and 10 control breast cancer cases not pregnancy-associated with similar clinicopathological features. We then analyzed protein expression for PTEN, BCL2 and PDCD4 as miR-21 target genes by IHC, and finally correlated the results with patients clinicopathological features.Significant overexpression of miR-21 in PABC tumors compared to normal adjacent tissue was found. Overexpression of miR-21 was frequently found in high grade tumors with loss of hormone receptor expression and was significantly associated with positive lymph nodes (p=0.025). In PABC patients, PTEN, BCL2 and PDCD4 target protein expression was decreased in 80%, 76% and 40% respectively.Conclusion: Our study supports the involvement of miR-21 in breast cancer progression and metastasis formation in PABC implying a role of this miRNA as a marker for poor prognosis in PABC patients.
Inactivation of the TCA cycle enzyme, fumarate hydratase (FH), drives a metabolic shift to aerobic glycolysis in FH-deficient kidney tumors and cell lines from patients with hereditary leiomyomatosis renal cell cancer (HLRCC), resulting in decreased levels of AMP-activated kinase (AMPK) and p53 tumor suppressor, and activation of the anabolic factors, acetyl-CoA carboxylase and ribosomal protein S6. Reduced AMPK levels lead to diminished expression of the DMT1 iron transporter, and the resulting cytosolic iron deficiency activates the iron regulatory proteins, IRP1 and IRP2, and increases expression of the hypoxia inducible factor HIF-1?, but not HIF-2?. Silencing of HIF-1? or activation of AMPK diminishes invasive activities, indicating that alterations of HIF-1? and AMPK contribute to the oncogenic growth of FH-deficient cells.
Hereditary leiomyomatosis renal cell carcinoma (HLRCC)-associated renal tumors are aggressive and tend to metastasize early. There are currently no effective forms of therapy for patients with advanced HLRCC-associated kidney cancer. We have previously shown that HLRCC cells express a high level of reactive oxygen species (ROS). In the present study we investigated the cytotoxic effects of increasing ROS level using bortezomib in combination with cisplatin on HLRCC cells in vitro and in an in vivo xenograft model. The cytotoxic effect of several ROS inducers on FH-deficient cells was assessed by synthetic lethality. ROS inducers had a pronounced impact on the viability of FH-deficient cells. Because of its high potency, the proteasome inhibitor bortezomib was further investigated. Bortezomib induced apoptosis in vitro in HLRCC cells and inhibited HLRCC tumour growth in vivo. Bortezomib-associated cytotoxicity was highly correlated with cellular ROS level: combining bortezomib with other ROS inducers enhanced cytotoxicity, while combining bortezomib with a ROS scavenger inhibited its cytotoxic effect. Finally, HLRCC murine xenografts were treated with bortezomib and cisplatin, another ROS inducer. This regimen induced HLRCC tumour regression in vivo. These findings suggest that increasing ROS level in HLRCC above a certain threshold can induce HLRCC-tumor cell death. Increasing tumor ROS with bortezomib in combination with cisplatin represents a novel targeted therapeutic approach to treat advanced HLRCC-associated renal tumors.
In this study, we aimed to evaluate the protein expression profile of a spectrum of renal cell carcinomas (RCC) to find potential biomarkers for disease onset and progression and therefore, prospective therapeutic targets. A 2D-gel based proteomic analysis was used to outline differences in protein levels among different subtypes of renal cell carcinomas, including clear cell carcinomas, papillary lesions, chromophobe tumors and renal oncocytomas. Spot pattern was compared to the corresponding normal kidney from the same patients and distinctive, differentially expressed proteins were characterized by mass spectrometry. Twenty-one protein spots were found differentially expressed between clear cell RCC and normal tissue and 38 spots were found expressed in chromophobe tumors. Eleven proteins were identified, with most differentially expressed -by fold change- between clear cell tumors and the corresponding normal tissue. Two of the identified proteins, Triosephosphate isomerase 1 (TPI-1) and Heat Shock protein 27 (Hsp27), were further validated in a separate set of tumors by immunohistochemistry and expression levels were correlated with clinicopathologic features of the patients. Hsp27 was highly expressed in 82% of the tumors used for validation, and all cases showed strong immunoreactivity for TPI-1. In both Hsp27 and TPI-1, protein expression positively correlated with histologic features of the disease. Our results suggest that the subjacent cytogenetic abnormalities seen in different histological types of RCC are followed by specific changes in protein expression. From these changes, Hsp27 and TPI-1 emerged as potential candidates for the differentiation and prognosis in RCC.
Germline mutations in a tumor suppressor gene FLCN lead to development of fibrofolliculomas, lung cysts and renal cell carcinoma (RCC) in Birt-Hogg-Dubé syndrome. TFE3 is a member of the MiTF/TFE transcription factor family and Xp11.2 translocations found in sporadic RCC involving TFE3 result in gene fusions and overexpression of chimeric fusion proteins that retain the C-terminal DNA binding domain of TFE3. We found that GPNMB expression, which is regulated by MiTF, was greatly elevated in renal cancer cells harboring either TFE3 translocations or FLCN inactivation. Since TFE3 is implicated in RCC, we hypothesized that elevated GPNMB expression was due to increased TFE3 activity resulting from the inactivation of FLCN.
Chordomas are low to intermediate grade malignancies that arise from remnants of embryonic notochord. They often recur after surgery and are highly resistant to conventional adjuvant therapies. Recently, the development of effective targeted molecular therapy has been investigated in chordomas that show receptors for tyrosine kinase (RTKs) activation. Expression of specific RTKs such as Epidermal Growth Factor Receptor (EGFR) and Mesenchymal-epithelial transition factor (c-MET) in chordomas may offer valuable therapeutic options. We investigated changes in copy number of chromosome 7 and correlated it with EGFR gene status and EGFR and c-MET protein expression in 22 chordoma samples. Chromosome 7 copy number was evaluated by chromogenic in situ hybridization (CISH) and protein expression of EGFR and c-MET by immunohistochemistry. Tumors mostly showed conventional histopathologic features and were found mainly in sacral (41%) and cranial sites (54.5%). Aneusomy of chromosome 7 was seen in 73% of the samples, 62% of primary tumors and in all recurrent chordomas. EGFR and c-MET were both expressed, but only c-MET protein expression was significantly correlated with chromosome 7 aneusomy (P ? 0.001). c-MET overexpression may represent an early chromosome 7 alteration that could play an important role during chordoma pathogenesis. c-MET overexpression shows promise as a molecular marker of response to targeted molecular therapy in the treatment of chordomas.
A method that relies on subtractive tissue-directed shot-gun proteomics to identify tumor proteins in the blood of a patient newly diagnosed with cancer is described. To avoid analytical and statistical biases caused by physiologic variability of protein expression in the human population, this method was applied on clinical specimens obtained from a single patient diagnosed with nonmetastatic renal cell carcinoma (RCC). The proteomes extracted from tumor, normal adjacent tissue and preoperative plasma were analyzed using 2D-liquid chromatography-mass spectrometry (LC-MS). The lists of identified proteins were filtered to discover proteins that (i) were found in the tumor but not normal tissue, (ii) were identified in matching plasma, and (iii) whose spectral count was higher in tumor tissue than plasma. These filtering criteria resulted in identification of eight tumor proteins in the blood. Subsequent Western-blot analysis confirmed the presence of cadherin-5, cadherin-11, DEAD-box protein-23, and pyruvate kinase in the blood of the patient in the study as well as in the blood of four other patients diagnosed with RCC. These results demonstrate the utility of a combined blood/tissue analysis strategy that permits the detection of tumor proteins in the blood of a patient diagnosed with RCC.
Germline mutations in the FLCN gene are responsible for the development of fibrofolliculomas, lung cysts and renal neoplasia in Birt-Hogg-Dube (BHD) syndrome. The encoded protein folliculin (FLCN) is conserved across species but contains no classic motifs or domains and its function remains unknown. Somatic mutations or loss of heterozygosity in the remaining wild type copy of the FLCN gene have been found in renal tumors from BHD patients suggesting that FLCN is a classic tumor suppressor gene.
Germline mutations in the BHD/FLCN tumor suppressor gene predispose patients to develop renal tumors in the hamartoma syndrome, Birt-Hogg-Dubé (BHD). BHD encodes folliculin, a protein with unknown function that may interact with the energy- and nutrient-sensing AMPK-mTOR signaling pathways. To clarify BHD function in the mouse, we generated a BHD knockout mouse model. BHD homozygous null (BHD(d/d)) mice displayed early embryonic lethality at E5.5-E6.5, showing defects in the visceral endoderm. BHD heterozygous knockout (BHDd(/+)) mice appeared normal at birth but developed kidney cysts and solid tumors as they aged (median kidney-lesion-free survival = 23 months, median tumor-free survival = 25 months). As observed in human BHD kidney tumors, three different histologic types of kidney tumors developed in BHD(d/+) mice including oncocytic hybrid, oncocytoma, and clear cell with concomitant loss of heterozygosity (LOH), supporting a tumor suppressor function for BHD in the mouse. The PI3K-AKT pathway was activated in both human BHD renal tumors and kidney tumors in BHD(d/+) mice. Interestingly, total AKT protein was elevated in kidney tumors compared to normal kidney tissue, but without increased levels of AKT mRNA, suggesting that AKT may be regulated by folliculin through post translational or post-transcriptional modification. Finally, BHD inactivation led to both mTORC1 and mTORC2 activation in kidney tumors from BHD(d/+) mice and human BHD patients. These data support a role for PI3K-AKT pathway activation in kidney tumor formation caused by loss of BHD and suggest that inhibitors of both mTORC1 and mTORC2 may be effective as potential therapeutic agents for BHD-associated kidney cancer.
Hereditary leiomyomatosis and renal cell cancer (HLRCC) is an inherited cancer syndrome linked to biallelic inactivation of the gene encoding the tricarboxylic acid cycle enzyme fumarate hydratase (FH). Individuals with HLRCC are at risk to develop cutaneous and uterine leiomyomas and an aggressive form of kidney cancer. Pseudohypoxic drive-the aberrant activation of cellular hypoxia response pathways despite normal oxygen tension-is considered to be a likely mechanism underlying the etiology of this tumor. Pseudohypoxia requires the oxygen-independent stabilization of the alpha subunit of the hypoxia-inducible transcription factor (HIF-1alpha). Under normoxic conditions, proline hydroxylation of HIF-1alpha permits VHL recognition and subsequent targeting for proteasomal degradation. Here, we demonstrate that inactivating mutations of FH in an HLRCC-derived cell line result in glucose-mediated generation of cellular reactive oxygen species (ROS) and ROS-dependent HIF-1alpha stabilization. Additionally, we demonstrate that stable knockdown of FH in immortalized renal epithelial cells results in ROS-dependent HIF-1alpha stabilization. These data reveal that the obligate glycolytic switch present in HLRCC is critical to HIF stabilization via ROS generation.
The genetic basis for the hereditary leiomyomatosis and renal cell cancer syndrome is germ-line inactivating mutation in the gene for the Krebs/tricarboxylic acid cycle enzyme, fumarate hydratase (FH), the enzyme that converts fumarate to malate. These individuals are predisposed to development of leiomyomas of the skin and uterus as well as highly aggressive kidney cancers. Inhibition of FH should result in significant decrease in oxidative phosphorylation necessitating that glycolysis followed by fermentation of pyruvate to lactate will be required to provide adequate ATP as well as to regenerate NAD+. Moreover, FH deficiency is known to up-regulate expression of hypoxia-inducible factor (HIF)-1alpha by enhancing the stability of HIF transcript. This leads to activation of various HIF-regulated genes including vascular endothelial growth factor and glucose transporter GLUT1 and increased expression of several glycolytic enzymes. Because lactate dehydrogenase-A (LDH-A), also a HIF-1alpha target, promotes fermentative glycolysis (conversion of pyruvate to lactate), a step essential for regenerating NAD+, we asked whether FH-deficient cells would be exquisitely sensitive to LDH-A blockade. Here, we report that hereditary leiomyomatosis and renal cell cancer tumors indeed overexpress LDH-A, that LDH-A inhibition results in increased apoptosis in a cell with FH deficiency and that this effect is reactive oxygen species mediated, and that LDH-A knockdown in the background of FH knockdown results in significant reduction in tumor growth in a xenograft mouse model.
The condition hereditary leiomyomatosis and renal cell carcinoma is characterized by cutaneous leiomyomas, uterine fibroids and aggressive papillary renal cell carcinoma. A number of our patients with hereditary leiomyomatosis and renal cell carcinoma had atypical adrenal nodules, which were further evaluated to determine whether these nodules were associated with hereditary leiomyomatosis and renal cell carcinoma.
The role of energy deregulation and altered/adapted metabolism in tumor cells is an increasingly important issue in understanding cancer. Hereditary leiomyomatosis and renal cell carcinoma (HLRCC) is an aggressive form of RCC characterized by germline mutation of fumarate hydratase (FH), followed by somatic loss of the remaining wild-type allele and known to be a highly metastatic and lethal malignancy compared to other RCCs. The intrinsic loss of normal tricarboxylic acid (TCA) cycle presumably aids tumorigenesis due to the necessary metabolic alterations required and the enforced dependence on glycolysis derived energy, mimicking the Warburg effect. Thus, there is considerable utility in establishing a preclinical cell model from these tumors to study energy metabolism deregulation, as well as developing new targeted therapeutic approaches for TCA cycle enzyme-deficient cancers. Here, we describe a new immortalized cell line, UOK268, derived from a patients primary HLRCC-associated kidney cancer. This represents the first primary renal cell line to model TCA cycle gene loss and provides a perfect partner cell line to our previously described metastasis-derived HLRCC-associated cell line, UOK262. We identified a novel germline FH missense mutation, p.His192Asp, and the subsequent loss of heterozygosity in UOK268. The UOK268 cell line expressed mutant FH protein, which localized to the mitochondria, but with loss of almost all catalytic activity. The UOK268 cells had severely compromised oxidative phosphorylation and increased glycolytic flux. Ingenuity pathways analysis of human mitochondria-focused cDNA microarray (hMitChip3) gene chip data confirmed the altered mRNA expression patterns of genes involved in several important pathways, such as lipid metabolism, apoptosis, and energy production/glycolysis. UOK268 provides a unique model of a primary cell line demonstrating an enforced, irreversible Warburg effect and, combined with UOK262, provides a unique in vitro preclinical model for studying the bioenergetics of the Warburg effect in human cancer.
This work characterizes the uptake of (11)C-acetate in prostate cancer (PCa), benign prostate hyperplasia, and normal prostate tissue in comparison with multiparametric MRI, whole-mount histopathology, and clinical markers to evaluate the potential utility of (11)C-acetate for delineating intraprostatic tumors in a population of patients with localized PCa.
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