Paclitaxel resistance and the role of miRNAs in prostate cancer cell lines.

PURPOSE: To investigate the expression profiles of 86 miRNAs in paclitaxel-resistant prostate cancer cell lines and to identify the genes that have a role in the development of drug resistance. METHODS: Three prostate cancer cell lines, androgen-dependent VCaP, androgen-independent PC-3 and DU-145, were used to obtain paclitaxel-resistant cells by progressively increasing the concentration of paclitaxel in the culture medium. Viability assays with 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium and sulforhodamine B were used to assess the cell resistance level and cytotoxic effects of paclitaxel treatment. Total RNA was isolated from both prostate cancer cell lines and their resistant versions, and cDNA samples were reverse transcribed from total RNA. Selected target genes of miRNAs that showed differences in expression and were estimated to be effective on drug resistance mechanism were analyzed with western blot analysis. RESULTS: Expression study of 86 miRNAs by RT-PCR demonstrated that several of the miRNAs were expressed at different levels in paclitaxel-resistant cells compared to wild-type cells. Moreover, the expression profiles of these miRNAs varied among different prostate cancer cell line types, with 13 miRNAs being up-regulated in the resistant cells. Among these, miR-200b-3p, miR-34b-3p and miR-375 exhibited a marked up-regulation. Further, miR-100-5p showed a prominent increase in paclitaxel-resistant VCaP-R and DU145-R cells. Western blot and RT-PCR studies showed that only the LARP1 and CCND1 genes were over-expressed up to 2-5 times in all paclitaxel-resistant cell lines compared to the other investigated genes. CONCLUSIONS: In this study, the three paclitaxel-resistant prostate cancer cell lines examined showed remarkably different miRNA expression profiles.