PARK2 suppresses the proliferation of high-grade serous ovarian carcinoma via inducing the proteasomal degradation of ZNF703.

High-grade serous ovarian cancer (HGSC) is an aggressive disease with poor prognosis. The oncoprotein ZNF703 is implicated in driving HGSC pathogenesis, but factors regulating its abundance remain unclear. In this study, we aim to investigate the potential connection between ZNF703 dysregulation and ubiquitin-mediated protein degradation in HGSC. Bioinformatics prediction was performed using BioGRID database. HGSC representative cell lines were utilized for in vitro and in vivo studies. Results showed that ZNF703 protein was stabilized upon proteasome inhibition, suggesting a regulation via ubiquitination. The ubiquitin E3 ligase PARK2 was found to interact with ZNF703 in a dose-dependent manner, promoting its polyubiquitination and subsequent proteasomal degradation. Re-expression of PARK2 in HGSC cells led to reduced ZNF703 levels together with decreased Cyclin D1/E1 abundance and G1 cell cycle arrest. ZNF703 overexpression alone increased S phase cells, Cyclin D1/E1 levels, and xenograft tumor growth, while co-expression with PARK2 mitigated these oncogenic effects. Collectively, our findings identify ZNF703 as a bona fide substrate of PARK2, reveal a tumor suppressive function for PARK2 in attenuating ZNF703-mediated G1/S transition and HGSC growth through instigating its degradation. This study elucidates a pivotal PARK2-ZNF703 axis with therapeutic implications for targeted intervention in HGSC.