Hexane fraction of var. root extract induces apoptosis of human lung cancer cells by inactivating Src/STAT3 pathway.

The aim of this study was to investigate the anticancer effect of var. (AT) root extract on human non-small cell lung cancer (NSCLC) cells and the mechanism involved in such effect. Among three fractions of AT root extract, hexane fraction (HAT) significantly decreased the proliferation of NSCLC cells. Besides, HAT treatment dose-dependently inhibited colony formation of NSCLC cells. These effects were associated with apoptosis induction evidenced by increased chromatin condensation, accumulation of sub-G1 DNA content and annexin V-positive cells, and enhanced expression of apoptotic proteins, including cleaved-caspases and cleaved-poly (ADP-ribose) polymerase (PARP). Notably, phosphorylation levels of signal transducer and activator of transcription 3 (STAT3) and Src were decreased by HAT. Transfection with STAT3 or Src for constitutive activation reversed the anti-proliferative effect of HAT on H1299 cells. Taken together, our findings suggest that HAT-induced apoptosis in NSCLC cells is mediated by inhibition of Src/STAT3 pathway.