MLK3 silence induces cervical cancer cell apoptosis via the Notch-1/autophagy network.

Mixed-lineage kinase 3 (MLK3), the mitogen-activated protein kinase kinase kinase (MAP3K), has been recognized as a player in tumorigenesis and oncogenic signalling, yet its detailed functions and signalling in cervical cancer have not been fully elucidated. Here, we identify that cervical cancer cells display higher mRNA and protein levels of MLK3 than normal cervical epithelial squamous cells. In HeLa and SiHa cell, MLK3 knockdown using siRNA remarkably suppressed cell survival and promoted cell apoptosis, with increased expression of the apoptosis-related protein Bax and reduced Bcl-2. Moreover, MLK3 knockdown promoted cell autophagy, demonstrated by increased ratio of autophagy-related proteins LC3II/LC3I and decreased p62 expression in MLK3 depletion cells. Furthermore, MLK3 knockdown remarkably abolished Notch-1 expression in cervical cancer cells. By co-treating Hela cells with MLK3 specific siRNA and pcDNA3.1-Notch-1 overexpression plasmid or autophagy inhibitor 3-MA, we found that MLK3 played its role in cervical cancer cells via the Notch-1/autophagy network. Our results demonstrate the importance of MLK3 in cervical cancer progression via modulating the Notch-1/autophagy network, and suggest that MLK3 is a promising therapeutic target for cervical cancer.