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

Abstract

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 ¼ 45) and benign prostatic hyperplasia (BPH) tissues (n ¼ 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 MTT 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.

ZFX acts as a transcriptional activator in multiple types of human tumors by binding downstream from transcription start sites at the majority of CpG island promoters

“…In accordance with findings from previous studies (Fang et al 2012(Fang et al , 2014aJiang et al 2012a;Yang et al 2014Yang et al , 2015, we found that the top categories of genes affected by ZFX knockdown are related to the cell cycle, to the DREAM complex (which contains E2F …”

“…We chose to use these cancer models because there is a strong link in these four cancer types between ZFX expression and cell proliferation, tumor development, or patient survival. For example, prostate cancer tissues exhibit significantly higher ZFX expression than benign prostatic hyperplasia and adjacent tissues and siRNAmediated knockdown of ZFX suppresses the proliferation of prostate cancer cells and reduces the number of colonies in colony forming assays (Jiang et al 2012a). Similarly, expression of ZFX is high in advanced invasive breast cancers and knockdown of ZFX reduces the proliferation rate of breast cancer cells (Yang et al 2014).…”

Overexpression of ZFX and its involvement in squamous cell carcinoma of the tongue

“…Consistent with the results that ZFX knockdown caused cell cycle arrest in tongue SCC cell lines, previous studies showed that ZFX knockdown could inhibit the expression of cell cycle factors such as cyclin D1 and B1 in multiple types of cancer (18,20,21). Studies also found that ZFX depletion enhanced the expression of apoptotic factors including bax, caspase 1, 3 and 9 or inhibited the expression of anti-apoptotic factor such as bcl-2 in diverse cancers (12)(13)(14)18,20,21), which may account for the ZFX knockdown-induced cell apoptosis. Thus, it is quite possible that these mechanisms also function in tongue SCC, and further investigations are urgently needed to elucidate the mechanisms associated with ZFX-mediated tongue SCC development.…”

Genome-wide analysis of AR binding and comparison with transcript expression in primary human fetal prostate fibroblasts and cancer associated fibroblasts

“…ZFX has been recognised as an oncogene in a number of cancers (reviewed in [68]). In prostate cancer cell lines, ZFX has been shown to drive cell proliferation and promote cell survival [69] and expression of ZFX has been shown to be elevated in prostate tumours [69,70]. There is no known link between the functions of ZFX and AR.…”