Ubiquitin conjugating enzyme E2 L3 promoted tumor growth of NSCLC through accelerating p27kip1 ubiquitination and degradation

The molecular pathogenesis of human lung cancer has not been completely clarified. Here, we reported that UBE2L3, a member of the ubiquitin-conjugating enzymes (E2s), were overexpressed in non-small-cell lung cancer (NSCLC) tissues compared with the non-tumor tissues. High expression of UBE2L3 was correlated with advanced tumor stage and adverse outcomes. Knockdown of UBE2L3 inhibited NSCLC cell growth while ectopic expression of UBE2L3 promoted NSCLC cell growth in a cell cycle dependent manner. The results of subcutaneous tumor xenograft studies revealed that knockdown of UBE2L3 attenuated the in vivo tumor growth. Mechanistically, we observed that UBE2L3 could interact with F-box protein Skp2, a member of the SCF (Skp2) ubiquitin ligase complex, and thus promoted the ubiquitination and proteasomal degradation of p27kip1. Furthermore, NSCLC cases with high level of UBE2L3 and low level of p27kip1 had worst prognosis, suggesting that combination of UBE2L3 and p27kip1 is a more powerful prognostic marker for NSCLC patients. Taken together, the current study presented a novel marker for predicting prognosis and a potential therapeutic target for NSCLC patients.