Cordycepin induces autophagy-mediated c-FLIPL degradation and leads to apoptosis in human non-small cell lung cancer cells

Cordycepin, a main active composition extracted from Cordyceps militaris, has been reported to exert anti-tumor activity in a broad spectrum of cancer types. However, the function of cordycepin on human non-small cell lung cancer cells is still obscure. Our present work showed that cordycepin inhibited cell growth by inducing apoptosis and autophagy in human NSCLC cells. Further study revealed that cordycepin triggered extrinsic apoptosis associated with down-regulation of c-FLIP(L) which suppresses the activity of caspase-8. And ectopic expression of c-FLIP(L) dramatically prevented cordycepin-caused apoptosis. Meanwhile, cordycepin stimulated autophagy through suppressing mTOR signaling pathway in lung cancer cells. When autophagy was blocked by Atg5 siRNA or PI3K inhibitor LY294002, the levels of apoptosis caused by cordycepin were obviously attenuated. In addition, suppression of autophagy could also elevate the level of c-FLIP(L) which indicated cordycepin-triggered autophagy promoted the degradation of c-FLIP(L). Therefore, we conclude that cordycepin induces apoptosis through autophagy-mediated downregulation of c-FLIP(L) in human NSCLC cells. Taken together, our findings provide a novel prospect on the anti-tumor property of cordycepin, which may further prompt cordycepin to serve as a promising therapeutic approach in NSCLC treatment.