Knockdown of zinc finger protein X-linked inhibits prostate cancer cell proliferation and induces apoptosis by activating caspase-3 and caspase-9

Zinc finger protein X-linked (ZFX) is a highly conservative mammalian gene with related functions in cell survival and proliferation. However, there are limited reports on regulation of ZFX as a therapeutic target in cancer treatment. In this study, the expression of ZFX in prostate cancer with matched normal adjacent tissues (n = 45) and benign prostatic hyperplasia (BPH) tissues (n = 16) were observed by immunohistochemical analysis. The effect of lentiviral siRNA (small interference RNA)mediated dysfunction of ZFX on the proliferation of prostate cancer cells was studied. ZFX mRNA and protein expression levels in prostate cancer cells (PC-3 and DU145) were analyzed by western blotting and real-time polymerase chain reaction (RT-PCR). The effects of siRNA targeting ZFX on growth, cell cycle and apoptosis of PC-3 cells were evaluated by MU assay and flow cytometry. We also investigated the effect of ZFX deletion on the activation of caspase-1, -3 and -9 by western blotting and colorimetric assay. Prostate cancer specimens appeared significantly higher (42.2% of cases being positive) than that observed in normal adjacent tissues (11.8% of cases being positive) and BPH tissues (12.5% of cases being positive). Repression of ZFX in the prostate cancer cells effectively suppressed the cellular proliferation and colony-formation ability, and led to G1 phase cell cycle arrest. Moreover, inhibition of ZFX-induced cell apoptosis by activating caspase-1, -3 and -9. In conclusion, ZFX represents the prominent role in the progression of prostate cancer and may be a promising therapy target for prostate cancer.