WW and C2 domain-containing protein-3 promoted EBSS-induced apoptosis through inhibiting autophagy in non-small cell lung cancer cells.

WW and C2 domain-containing protein-3 (WWC3) was identified in our previous studies as a tumor suppressor gene, which inhibits the proliferation and invasiveness of lung cancer cells. However, the relationship between WWC3 and autophagy and apoptosis in lung cancer cells is unclear. In this study, we aimed to investigate the potential role of WWC3 in starvation-induced autophagy and apoptosis in non-small cell lung carcinoma (NSCLC) cells. The immunoblotting assay and quantitative real-time polymerase chain reaction (RT-qPCR) were used for observing the change of WWC3 protein and mRNA level under starvation condition. The immunoblotting assay and immunofluorescence assay were performed to detect the impact of WWC3 expression on autophagy process induced by Earle's balanced salt solution (EBSS) in lung cancer cells; APC/propidium iodide (PI) apoptosis assay, caspase-3/7 activity assay and MTT assay were used for the apoptosis and proliferation detection of lung cancer cells. After starvation had been induced with EBSS, WWC3 expression was significantly decreased in the NSCLC cells. Ectopic WWC3 expression weakened the autophagy process in a Beclin1-independent manner and promoted non-small cell lung cancer cell apoptosis via EBSS starvation. Moreover, the inhibition of WWC3 gene knockout was weakened by 3-methyladenine (3-MA), an autophagy inhibitor. These results indicate that WWC3 promotes apoptosis and death of starved lung cancer cells, at least partly through autophagy.