Evodiamine activates autophagy as a cytoprotective response in murine Lewis lung carcinoma cells

Autophagy is a self-defense mechanism that provides nutrition and energy for cell survival by recycling the cytoplasm and organelles. Hence, chemotherapy is rendered less effective against cancer cells. Evodiamine is a previously described biological agent that possesses a cytotoxic activity in multiple cancer cells. However, little is known about evodiamine-induced autophagy in Lewis lung carcinoma (LLC) cells. In this study, LLC cells and a xenograft model were used. By use of a panel of techniques such as MTT assay, flow cytometry, western blotting, immunocytochemistry and TUNEL assay, the effects on the induction of apoptosis and autophagy were evaluated. We demonstrated that evodiamine inhibited LLC cell growth and induced apoptosis through caspase-independent manner in vitro and caspase-dependent pathway in vivo. In addition, we showed for the first time that evodiamine promoted autophagosome formation by enhancing the conversion of microtubule-associated protein 1 light chain 3 (LC3)-I to LC3-II and upregulating the expression of autophagy-specific genes (Atgs). Moreover, 3-methyladenine (3-MA), an autophagy inhibitor, attenuated evodiamine-induced autophagy through decreasing the conversion of LC3-I to LC3-II. The inhibition of autophagy was found to increase cell death and enhance evodiamine-induced apoptosis in vitro in a caspase-independent manner and in vivo in a caspase-dependent manner. In conclusion, evodiamine promoted autophagy in LLC cells and autophagy inhibition enhanced evodiamine-induced apoptosis in vitro and in vivo. These results demonstrate that evodiamine-induced autophagy plays a cytoprotective role in LLC cells and evodiamine combined with autophagy inhibitor therapy could increase the chemosensitivity of LLC cells.