TRAIP suppresses bladder cancer progression by catalyzing K48-linked polyubiquitination of MYC
Tumor necrosis factor (TNF) receptor-associated factor (TRAF)-interacting protein (TRAIP), a RING domain-containing E3 ligase, has emerged as a key player in safeguarding genome integrity and is closely linked to cancer. Here, we discovered that TRAIP exhibits low expression in bladder cancer (BLCA), which correlates with poor prognosis. TRAIP exerts inhibitory effects on bladder cancer cell proliferation and migration both in vitro and in vivo. MYC serves as a newly identified target for TRAIP, with direct interaction leading to the promotion of K48 polyubiquitination at K428/430 lysine residues, subsequently resulting in proteasome-dependent degradation and downregulation of MYC's transcriptional activity. This process effectively hinders the progression of bladder cancer. Restoration of MYC expression rescues the suppressed proliferation and migration of bladder cancer cells induced by TRAIP. Furthermore, our investigation also demonstrates that MYC binds to the transcriptional start region of TRAIP, exerting regulatory control over TRAIP transcription. Consequently, this interaction establishes a negative feedback loop that prevents excessive expression of MYC. In summary, our study uncovers a novel mechanism by which TRAIP inhibits the progression of bladder cancer through the ubiquitinated degradation of MYC. Overall design: To investigate the downstream mechanism of TRAIP regulation of bladder cancer, we performed RNA sequencing on three repeated siNC and siTRAIP-treated T24 cells.