Trifolin induces apoptosis via extrinsic and intrinsic pathways in the NCI-H460 human non-small cell lung-cancer cell line.

BACKGROUND

Trifolin (kaempferol-3-O-galactoside), which is a galactose-conjugated flavonol, exhibits antifungal and anticancer effects. However, the mechanisms underlying its anticancer activities have not yet been examined.

PURPOSE

In this study, the anticancer effects of trifolin were examined in human lung cancer cells.

METHODS

Cytotoxicity was determined by evaluating cell viability. Apoptosis was analyzed through flow cytometry and western blotting analysis. Death receptors and inhibitors of apoptosis were evaluated through RT-PCR.

RESULTS

Trifolin induced apoptosis in NCI-H460 human non-small cell lung cancer (NSCLC) cells by inhibiting the survival pathway and inducing the intrinsic and extrinsic apoptosis pathways. Trifolin decreased levels of Akt/p-Akt, whereas levels of expression of phosphatidylinositide 3-kinase (PI3K), cyclin D1, cyclin E, and cyclin A were not altered. Trifolin initiated cytochrome c release by inducing mitochondrial outer membrane permeabilization (MOMP). Trifolin increased Bcl-2-associated X protein (Bax) levels and decreased b-cell lymphoma 2 (Bcl-2) levels, while the levels of Bcl-xL were not altered. In addition, trifolin increased the levels of the death receptor involving the Fas/Fas ligand (FasL) and Fas-associated protein with the death domain (FADD), which consequently activated caspase-8, caspase-9, caspase-3, and the proteolytic cleavage of poly (ADP-ribose) polymerase (PARP).

CONCLUSION

These results suggested that trifolin induced apoptosis via death receptor-dependent and mitochondria-dependent pathways and that trifolin can be used as a therapeutic agent in human lung cancer.