RNF6 activates JNK/c-JUN pathway in ovarian cancer by promoting K48-linked NME4 ubiquitination

RING finger protein 6 (RNF6), a member of the E3 ubiquitin ligase family, has been implicated in various cancers, yet its functional significance and regulatory mechanisms in ovarian cancer (OC) are poorly understood.

RNF6 expression levels were analyzed using TCGA data and confirmed by IHC, qRT-PCR, and western blotting in OC tissues or cell lines. Functional roles of RNF6 were evaluated through CCK-8, colony formation, wound healing, Transwell, and EMT marker assays. Protein interactions and ubiquitination patterns were investigated via Co-IP, CHX chase, and ubiquitination assays. Rescue experiments were conducted by co-modulating RNF6 and NME4 expression. In vivo tumorigenesis was assessed using a nude mouse xenograft model.

RNF6 was markedly overexpressed in OC and associated with poor prognosis. Silencing RNF6 suppressed cell growth, invasive behavior, and EMT, while enhancing NME4 expression. Mechanistic analyses demonstrated that RNF6 directly binds to NME4 and facilitates its K48-linked polyubiquitination, leading to proteasomal degradation. Knockdown of NME4 reversed the tumor-suppressive effects of RNF6 depletion and reinstated JNK/c-JUN pathway activation. In vivo, RNF6 silencing significantly reduced tumor burden and impaired downstream signaling events.

RNF6 contributed to OC malignancy by destabilizing NME4 and activating the JNK cascade. This newly identified RNF6/NME4/JNK axis provides potential targets for therapeutic intervention in OC.