Inhibition of p22(phox) Suppresses Epithelial Ovarian Cancer Cell Proliferation and Tumorigenesis

The aim of this study was to investigate the biological role and molecular mechanism of p22(phox) in epithelial ovarian cancer. Immunohistochemistry was employed to determine the p22(phox) expression level in epithelial ovarian cancer tissues. The effects of p22(phox) on epithelial ovarian cancer cell proliferation, tumorigenesis, and chemosensitivity were evaluated by CCK-8, EdU assay, colony formation and apoptosis assays in vitro and by mouse experiments in vivo. Immunoprecipitation analyses were utilized to explore the potential mechanisms of p22(phox) mediated downstream signaling, and RT-PCR and western blot were used to confirm the relevance. P22(phox) expression could be detected in epithelial ovarian cancer tissues and normal fallopian epithelial cells. Silencing p22(phox) suppressed epithelial ovarian cancer cell proliferation and colony formation capacity in vitro, and inhibited the tumor growth in nude mice bearing the A2780 xenograft in vivo. Mechanistic investigations showed that p22(phox) regulated proteasome ubiquitination and subsequent proteasome-dependent degradation of p53 in A2780 and U87 cells in vitro. Furthermore, knockdown of p22(phox) significantly increased the chemosensitivity of A2780 cells to cisplatin or paclitaxel. These results suggested that p22(phox) as a pivotal oncogene during epithelial ovarian cancer carcinogenesis and p22(phox) inhibition might be a potential therapeutic strategy for epithelial ovarian cancer.