Abstract: Objective To investigate the expression of DNA methyltransferases (DNMTs) in prostate cancer tissues and prostate cancer cell lines and the effects on cell proliferation, apoptosis, migration and invasion of prostate cancer cells in vitro. Methods The prostatic tissue samples were collected from 24 patients, including 12 prostate cancer and 12 benign prostatic hyperplasia. Immunohistochemical staining was used to detect the expression of DNMT1 and DNMT3b protein. The prostate cancer cell lines (DU145, PC-3) and human normal prostate epithelial cell line (RWPE-1) were cultured. The expression of DNMT1 and DNMT3b was detected by Western blot and RT-qPCR. SiRNA was used to down regulate the expression of DNMT1 and DNMT3b in DU145 cells, and the changes in biological behaviors of DU145 cells were detected. Results The expression of DNMT1 and DNMT3b in prostate cancer tissues was higher than that in benign prostatic hyperplasia (P<0.05). The expression of DNMT1 and DNMT3b in DU145 and PC-3 cells was higher than that in RWPE-1 cells (P<0.05), and the expression of DNMT1 and DNMT3b in DU145 cells was higher than that in PC-3 cells (P<0.05). Down regulation of the expression of DNMT1 and DNMT3b in DU145 cells could significantly inhibit cell proliferation, promote cell apoptosis and reduce cell migration and invasion (P<0.05), in which the DNMT1 inhibition group had the most significant effect. Conclusions The expression of DNA methyltransferases (DNMT1 and DNMT3b) in prostate cancer is higher than that in normal prostate, and DNMT1 has the most significant effect on cell biological behaviors.

Key words: prostate cancer, DNA methylation, DNA methyltransferase, siRNA