Targeting ubiquitin-specific protease 14 reduces metastatic potential and metabolic activity in cervical cancer via direct modulation of monocarboxylate transporter-4

Background: Cervical cancer (CC) remains a major health burden in low- and middle-income countries, where HPV vaccination coverage is suboptimal. Ubiquitin-specific peptidase 14 (USP14), a proteasome-associated deubiquitinase, has emerged as a potential driver of tumorigenesis, but its role in CC and impact on tumor metabolism remain poorly defined. Methods: In-silico analysis of RNA and proteomics data from publicly available datasets was performed to assess the expression and prognostic value of USP14. Expression was validated in CC cell lines (HeLa, SiHa, CaSki) in comparison to non-transformed MCF10A cells. Functional studies involved USP14 knockdown (siRNA) or inhibition (IU1), followed by various cell viability, metastasis and invasion assays. Comparative proteomics was employed to identify USP14 interacting partners, with a particular focus on monocarboxylate transporter 4 (MCT4). USP14-MCT4 interactions were confirmed by co-immunoprecipitation, ubiquitination assays, and molecular dynamics simulations. Immunohistochemistry was performed on retrospective cervical squamous cell carcinoma tissues to correlate USP14 and MCT4 expression. Results: High USP14 expression correlated with poor overall survival in CC patients and was elevated in CC cell lines. Genetic or pharmacological inhibition of USP14 significantly reduced CC cell proliferation, metastasis, and invasion. Proteomic profiling identified MCT4, a key lactate transporter in tumor metabolism, as a novel USP14 interactor. USP14 knockdown decreased MCT4 protein levels and stability, suggesting deubiquitination-dependent regulation. Immunoprecipitation confirmed direct binding between USP14 and MCT4, and molecular dynamics simulations revealed distinct binding interfaces. In patient tissues, USP14 and MCT4 expression were positively correlated. Conclusion: This study uncovers MCT4 as a novel substrate of USP14, linking USP14 activity to metabolic reprogramming in CC. The USP14-MCT4 axis represents a previously unrecognized oncogenic pathway with therapeutic potential. Targeting USP14 could simultaneously impair tumor growth and disrupt lactate metabolism, offering a promising strategy for CC treatment.