DNA methylation regulates the expression of Y chromosome specific genes in prostate cancer

Purpose: We hypothesized that DNA methylation regulates the differential expression of Y chromosome specific genes in prostate cancer. To test this hypothesis we analyzed the expression of Y chromosome specific genes in 5-aza-2 ' -deoxycytidine (5-azaC) treated and untreated prostate cancer cell lines. Materials and Methods: To test this hypothesis Y chromosome specific genes were analyzed in prostate cancer cells treated with the demethylation agent 5-azaC. Total RNA was extracted and reverse transcribed, and polymerase chain reaction was performed using gene specific primers. These primers were designed based on the sequence available in the public genome data bank. The 10 Y chromosome specific genes DAZ, CDY, SRY, RBMY1A, RBMY1H, RBMII, BPY1, BPY2, PRY and TSPY were analyzed in the PC3, ND1, DU145, LNCaP, TSUPr1 and DUPro prostate cancer cell lines by reverse transcriptase-polymerase chain reaction. Normal testis RNA was used as a positive control. Results: Of the 10 Y chromosome specific genes DAZ gene expression was lacking in all prostate cancer cell lines but after demethylation treatment with 5-azaC DAZ expression was restored. The SRY gene was also lacking in all prostate cancer cell lines except LNCaP. After demethylation SRY gene expression was restored in PC3, ND-1, DU-145, TSUPr1 and Dupro. There was no expression of the CDY and BPY2 genes before and after 5-azaC treatment in all prostate cancer cell lines. Expression of the RBMYY1A, RBMY1H and RBMII genes was lacking in all prostate cancer cell lines but after demethylation the expression of all 3 was restored in the ND1, DU-145 and LNCaP cell lines. The BPY1 gene was only expressed in LNCaP cells but after treatment with 5-azaC all other cell lines, namely PC3, ND1, DU145, LNCaP and DUPro, restored BPY gene expression. PRY gene expression was lacking in all prostate cancer cell lines but after demethylation only LNCaP restored expression of this gene. TSPY was expressed only in LNCaP but after demethylation ND-1 cells restored expression of the TSPY gene. Conclusions: To our knowledge we report the first study showing that expression of the Y chromosome specific genes DAZ, SRY, RBMY1A, RBMY1H, RBMII, BPY1, PRY and TSPY is regulated by DNA methylation in prostate cancer.