The loss of WIF1 expression in the majority of human PCa cell lines is associated with its promoter hypermethylation. A&B, the expression of WIF1 mRNA in eight PCa cell lines (LNCaP, LAPC4, 22Rv1, PC3, DU145, C4-2B, PC3 M, PC3-LN4) and PrEC were detected by regular RT-PCR and quantified by real-time RT-PCR. Experiments were replicated thrice. C, WIF1 promoter hypermethylation is evident in seven of eight PCa cell lines. The methylation status of WIF-1 promoter was determined by the disulfite treatment of cell lines followed by methylation-specific PCR; M, methylation-specific primers; UM, unmethylation-specific primers. D, WIF1 expression in PC3 was reactivated by a demethylation agent 5-Aza-dC. After PC3 cells were treated with 5-Aza-dC (5 μmol/L) for 72 h, RT-PCR was done to detect the WIF1 mRNA expression.