MicroRNAs (miR) are small, noncoding RNAs that regulate gene expression. In particular, miRs are involved in many biological processes, including differentiation, proliferation and cell death. In addition to their physiological functions, miRs are found to be aberrantly expressed in many carcinomas including renal tumors and to play oncogenic or tumor suppressive roles in cancer cells (1-2). Because, we have observed by microarray analysis that some miRs (miR 142-5p, 601, 362, 196b, 202 and 501) were differentially expressed in autosomal dominant polycystic kidney disease (ADPKD) which is an hyperproliferative disease, we have analyzed the expression of these miRs in kidney carcinomas to better understand their role in renal tumorigenesis. In particular, we have studied the most common renal neoplasms as clear cell (ccRCC), papillary (pRCC), chromophobe (chRCC), with respect to normal kidney tissues. Materials and Methods: We selected and analyzed 39 post-nephrectomy fresh frozen tissues (including 23 neoplastic samples: 14 ccRCC, 6 pRCC, 3 chRCC), and 13 paraffin-embedded tumors samples (7 ccRCC, 4 pRCC, 2 chRCC) with matched normal tissues. Total RNA was extracted with TRIZOL (fresh frozen tissues) or the RecoverAll® Total Nucleic Acid Isolation kit (paraffin-embedded tissues). Microarray analysis was performed in normal kidney and ADPKD cell lines following the manufacturer’s protocols of microarray facility (Lab of Dr. Negrini, University of Ferrara). Quantitative real time PCR for mature miRs was performed with TaqMan method. MicroRNA levels were expressed as ΔΔCt relative to reference gene U6 snRNA. MiR RNA levels in tumor sample were compared with ΔΔ those of normal tissue as fold increase calculated by 2-Ct method (3). Results: By real time RT-PCR analysis of indicated miRs, only the miR-501 was found differentially expressed in kidney carcinomas compared with normal renal tissues. In particular miR-501 expression was 5.35 fold increased in ccRCC with respect to normal tissues. Conversely, in pRCC this miR was found 2.56 fold decreased compared with normal kidney. Because, the expression levels of miR-501 in ccRCC showed a extremely variable distribution, this miR may not be used as a marker for ccRCC. Moreover, no correlation between miR-501 expression and tumor grading was observed. However, the low expression of miR-501 in ccRCC as well as in pRCC samples correlated with a good prognosis, thus the downregulation of miR501 could be considered as a marker for positive prognosis in ccRCC and pRCC kidney carcinomas. Conclusion: Our results demonstrate that in renal carcinomas the miR-501 was significantly over-expressed in ccRCC, while was downregulated in pRCC. High levels of miR-501 are not related with grading and metastasis in ccRCC, however, when it is down-regulated could promote a good prognosis.

Role of the miR-501 in Renal Carcinomas

MANGOLINI, Alessandra;BONON, Anna;MAGRI, Eros;QUERZOLI, Patrizia;PEDRIALI, Massimo;RUSSO, Gian Rosario;DEL SENNO, Laura;AGUIARI, Gianluca
2012

Abstract

MicroRNAs (miR) are small, noncoding RNAs that regulate gene expression. In particular, miRs are involved in many biological processes, including differentiation, proliferation and cell death. In addition to their physiological functions, miRs are found to be aberrantly expressed in many carcinomas including renal tumors and to play oncogenic or tumor suppressive roles in cancer cells (1-2). Because, we have observed by microarray analysis that some miRs (miR 142-5p, 601, 362, 196b, 202 and 501) were differentially expressed in autosomal dominant polycystic kidney disease (ADPKD) which is an hyperproliferative disease, we have analyzed the expression of these miRs in kidney carcinomas to better understand their role in renal tumorigenesis. In particular, we have studied the most common renal neoplasms as clear cell (ccRCC), papillary (pRCC), chromophobe (chRCC), with respect to normal kidney tissues. Materials and Methods: We selected and analyzed 39 post-nephrectomy fresh frozen tissues (including 23 neoplastic samples: 14 ccRCC, 6 pRCC, 3 chRCC), and 13 paraffin-embedded tumors samples (7 ccRCC, 4 pRCC, 2 chRCC) with matched normal tissues. Total RNA was extracted with TRIZOL (fresh frozen tissues) or the RecoverAll® Total Nucleic Acid Isolation kit (paraffin-embedded tissues). Microarray analysis was performed in normal kidney and ADPKD cell lines following the manufacturer’s protocols of microarray facility (Lab of Dr. Negrini, University of Ferrara). Quantitative real time PCR for mature miRs was performed with TaqMan method. MicroRNA levels were expressed as ΔΔCt relative to reference gene U6 snRNA. MiR RNA levels in tumor sample were compared with ΔΔ those of normal tissue as fold increase calculated by 2-Ct method (3). Results: By real time RT-PCR analysis of indicated miRs, only the miR-501 was found differentially expressed in kidney carcinomas compared with normal renal tissues. In particular miR-501 expression was 5.35 fold increased in ccRCC with respect to normal tissues. Conversely, in pRCC this miR was found 2.56 fold decreased compared with normal kidney. Because, the expression levels of miR-501 in ccRCC showed a extremely variable distribution, this miR may not be used as a marker for ccRCC. Moreover, no correlation between miR-501 expression and tumor grading was observed. However, the low expression of miR-501 in ccRCC as well as in pRCC samples correlated with a good prognosis, thus the downregulation of miR501 could be considered as a marker for positive prognosis in ccRCC and pRCC kidney carcinomas. Conclusion: Our results demonstrate that in renal carcinomas the miR-501 was significantly over-expressed in ccRCC, while was downregulated in pRCC. High levels of miR-501 are not related with grading and metastasis in ccRCC, however, when it is down-regulated could promote a good prognosis.
2012
miR-501; Renal Carcinoma
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11392/1729711
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