UBE2V1 Promotes Hepatocellular Carcinoma Progression by Forming a Positive Feedback Loop with HIF-1α

Hepatocellular carcinoma (HCC) is characterized by a profoundly hypoxic microenvironment, which drives tumor aggressiveness and poor clinical outcomes. However, the precise regulatory mechanisms through which hypoxia promotes HCC progression remain incompletely understood. Here, we identified ubiquitin conjugating enzyme E2 variant 1 (UBE2V1) as a novel hypoxia-responsive gene that is transcriptionally activated by hypoxia-inducible factor-1α (HIF-1α) through direct binding to a hypoxia-response element located between -208 and -201 bp in the UBE2V1 promoter. Overexpression of UBE2V1 was frequently detected in HCC tissues and correlated strongly with advanced tumor stage and unfavorable patient prognosis. Moreover, UBE2V1 facilitated the proliferation and migration of HCC cells. Further investigation revealed that up-regulated UBE2V1 competes with HIF-1α for binding to the β-domain of von Hippel-Lindau (VHL) protein and, in complex with UBE2S, catalyzes K11/K48-linked ubiquitination at VHL K196, leading to its proteasomal degradation. This disruption of VHL function attenuates HIF-1α ubiquitination and degradation, resulting in sustained HIF-1α stabilization, increased nuclear accumulation, and enhanced transcriptional activity. Consistent with these findings, genetic knockdown of UBE2V1 or pharmacological inhibition of HIF-1α markedly suppresses HCC tumorigenesis and metastasis in vivo. Altogether, our study unveils a previously unrecognized HIF-1α-UBE2V1 positive feedback loop that is self-reinforcing and critically sustains the hypoxic microenvironment to drive HCC progression, highlighting UBE2V1 as both a promising prognostic biomarker and a compelling therapeutic target for HCC.