UCHL3 regulates snail stability and promotes epithelial-mesenchymal transition in ovarian cancer.

Ovarian cancer (OC) is the most lethal gynecologic malignancy, characterized by high recurrence rates and resistance to platinum-based chemotherapy. Epithelial-mesenchymal transition (EMT) is central to OC progression, where the transcription factor Snail plays a pivotal role in downregulating E-cadherin and promoting invasive, mesenchymal phenotypes. While multiple deubiquitinating enzymes (DUBs) have been implicated in stabilizing oncogenic proteins, the specific function of ubiquitin C-terminal hydrolase L3 (UCHL3) in OC remains unclear. This study investigates whether UCHL3 regulates Snail stability and thereby drives EMT and OC progression. Publicly available datasets (TCGA + GTEx) were analyzed to compare UCHL3 mRNA levels across various tumors and corresponding normal tissues. In vitro, UCHL3 expression was measured by qPCR and Western blot in an immortalized ovarian epithelial cell line (IOSE80) and four OC cell lines (SKOV3, ES2, OVCAR3, and A2780). Stable knockdowns of UCHL3 were generated using shRNA in SKOV3 and A2780 cells. Proliferation was evaluated by CCK-8 and colony formation assays, while invasion and migration capabilities were assessed using Matrigel invasion and Transwell migration assays. EMT marker expression was examined by qPCR and Western blot. Co-immunoprecipitation (Co-IP) determined the interaction between UCHL3 and Snail, and the effect of UCHL3 on Snail ubiquitination was explored using immunoprecipitation in the presence of MG132. A cycloheximide chase assay confirmed Snail protein stability. UCHL3 was significantly overexpressed in OC tissues compared to normal controls. Silencing UCHL3 in OC cells markedly impaired cell proliferation, migration, and invasion. Concomitantly, knockdown of UCHL3 reversed EMT features, evidenced by increased E-cadherin and decreased N-cadherin, Vimentin, and Snail protein levels. Co-IP experiments demonstrated that UCHL3 directly interacts with Snail, and loss of UCHL3 elevated Snail ubiquitination, leading to accelerated Snail protein degradation. These findings indicate that UCHL3 deubiquitinates and stabilizes Snail, promoting OC cell invasiveness and EMT. Our study identifies UCHL3 as a critical regulator of Snail-mediated EMT in OC. By stabilizing Snail, UCHL3 fosters malignancy-associated phenotypes, including enhanced proliferation, migration, and invasion. These results underscore the potential of targeting UCHL3 as a therapeutic strategy to disrupt Snail-driven EMT and impede OC progression. Supplementary Information: The online version contains supplementary material available at 10.1007/s10616-025-00811-w.