Downregulation of LEF1 Impairs Myeloma Cell Growth Through Modulating CYLD/NF-κB Signaling.

Aberrant expression of lymphoid enhancer-binding factor-1 (LEF1) has been identified in various hematological malignancies including multiple myeloma (MM). However, the exact role of LEF1 in MM remains largely unknown. Here, we showed that knockdown of LEF1 could apparently impair the proliferation, induce apoptosis and promote the ROS production in MM cell lines, suggesting that LEF1 might be involved in maintaining MM cell growth and survival. Moreover, we observed that the mRNA level of the deubiquitinase cylindromatosis (CYLD), a well-recognized tumor suppressor in MM, was significantly increased following LEF1 depletion in myeloma cells. Further study showed that LEF1 could directly associate with the promoter of CYLD gene and thus repress its transcription in MM cells. Intriguingly, LEF1 depletion-mediated CYLD upregulation was sufficient to negatively modulate NF-κB signaling pathway in MM cells. Moreover, the decrease in NF-κB activity following LEF1 knockdown could be largely rescued when CYLD was silenced in MM cells. Taken together, our study provided the compelling evidence to show that LEF1 may augment the proliferation and survival of MM cells through direct repression of CYLD transcription and subsequent activation of NF-κB signaling pathway, corroborating that LEF1 may become a potential therapeutic target against MM.