Abstract 4418: Investigation of miR-205 expression and its methylation status in prostate cancer

• Published in: Cancer research (Chicago, Ill.) Ill.), 2018-07, Vol.78 (13_Supplement), p.4418-4418
• Main Authors: Lynch, Seodhna M., O'Neill, Karla M., McKenna, Michael M., Walsh, Colum P., Watson, William, Gallagher, William M., McKenna, Declan J.
• Format: Article
• Language: English
• ISSN: 0008-5472; 1538-7445
• DOI: 10.1158/1538-7445.AM2018-4418

Introduction: In prostate cancer (PCa), abnormal expression of several microRNAs (miRNAs) has been previously reported. Increasing evidence shows that aberrant epigenetic regulation of miRNAs is a contributing factor to their altered expression in cancer. In this study, we investigated whether expression of miR-205 in PCa is related to the DNA methylation status of its promoter and locus region. Methods: PCR analysis of miR-205 expression was performed in PCa cell lines and in clinical FFPE biopsy and prostatectomy specimens. CpG methylation analysis of the miR-205 promoter and miR-205 locus, was performed in PCa cell lines and in clinical prostate specimens via pyrosequencing. The effect on promoter and locus methylation status in cells treated with demethylating agents including 5-aza-2'deoxycytidine (decitabine), knockdown of DNA methyltransferase 1 (DNMT1) and knockdown of enhancer of zeste homolog 2 (EZH2) was also examined. Finally, the biological significance of miR-205 in PCa cells was assessed by a series of in vitro bioassays. Results: miR-205 was shown to be significantly down-regulated across PCa cell lines. This correlates inversely with the methylation status of the miR-205 promoter and miR-205 locus, which is hypermethylated across this panel of PCa cell lines in both regions. Interestingly, a trend towards an inverse correlation was evident between miR-205 methylation, for both regions, and miR-205 expression levels in clinical prostatectomy biopsy specimens. Moreover, in PC3 cells, miR-205 expression was subsequently elevated by treatment with the demethylating agents including 5-aza-2 deoxycytidine and knockdown of DNMT1 and EZH2, suggesting its expression is regulated by methylation. miR-205 promoter and locus methylation status, following treatment with 5-aza-2 deoxycytidine in PC3 cells, showed no change in methylation levels in either region. Finally, in vitro over-expression of miR-205 in PC3 cells inhibited growth and clonogenic potential, as well as inducing apoptosis. Conclusions: Preliminary findings to date provide evidence that miR-205 is abnormally expressed in PCa and appears to have a tumour suppressor role in PCa. This study investigated the role of DNA methylation in regulating miR-205 expression. It is evident that DNA methylation of the regions analysed may not be responsible for regulating miR-205 expression; thus, other regions within the promoter and locus region which have not been identified may be more important. F