Uev1A counteracts oncogenic Ras stimuli in both polyploid and diploid cells.

Oncogenic Ras is known to induce DNA replication stress, leading to cellular senescence or death. In contrast, we found that it can also trigger polyploid Drosophila ovarian nurse cells to die by inducing aberrant division stress. To explore intrinsic protective mechanisms against this specific form of cellular stress, here, we conducted a genome-wide genetic screen and identified the E2 enzyme Uev1A as a key protector. Reducing its expression levels exacerbates the nurse cell death induced by oncogenic Ras, while overexpressing it or its human homologs, UBE2V1 and UBE2V2, mitigates this effect. Although Uev1A is primarily known for its non-proteolytic functions, our studies demonstrate that it collaborates with the E3 APC/C complex to mediate the proteasomal degradation of Cyclin A, a key cyclin that drives cell division. Furthermore, Uev1A and UBE2V1/2 also counteract oncogenic Ras-driven tumorigenesis in diploid cells, suppressing the overgrowth of germline tumors in Drosophila and human colorectal tumor xenografts in nude mice, respectively. Remarkably, elevated expression levels of UBE2V1/2 correlate with improved survival rates in human colorectal cancer patients harboring oncogenic KRAS mutations, indicating that their upregulation could represent a promising therapeutic strategy.