Peptidylarginine deiminase 4 (PADI4) is an enzyme that converts both histone arginine and mono-methyl arginine residues to citrulline, and it has been detected in various subtypes of ovarian cancer. However, the mechanism of action of PADI4 in ovarian carcinogenesis remains unknown. To examine the function of PADI4, we transfected two ovarian cancer cell lines, wild-type p53 A2780 and p53-null SKOV3, with PADI4-siRNA and negative control siRNA. The proliferation of both A2780 and SKOV3 cells decreased significantly following PADI4-siRNA treatment (P A2780 < 0.01; P SKOV3 < 0.001). The invasion and migration ability of A2780 cells also significantly decreased in response to PADI4-siRNA treatment (P < 0.001), but SKOV3 cells showed no such decrease. The apoptotic rate of A2780 cells increased in the presence of PADI4-siRNA, but there was no such increase in SKOV3 cells (P > 0.05). PCR arrays of A2780 cells treated with PADI4-siRNA revealed the up-regulated expression of six genes, including cell death-inducing DFFA-like effector a (CIDEA) and tumor necrosis factor receptor superfamily member 9 (TNFRSF9), and the down-regulation of seven genes, including integrin beta 3 (ITGB3) and BCL2-antagonist/killer 1 (BAK1). These results suggest an important role for PADI4 in the p53 pathway and the regulation of the proliferation, apoptosis, invasion and migration of ovarian cancer cells. Our study also demonstrated that PADI4 contributes to tumor metastasis by regulating the gene expression of insulin-like growth factor 1 (IGF1) and WAS/WASL-interacting protein family member 1 (WIPF1).
Keywords: Apoptosis; Cell proliferation; Invasion; Migration; Ovarian cancer; Peptidylarginine deiminase 4.