Resveratrol analogue 3,4,4'-trihydroxy-trans-stilbene induces apoptosis and autophagy in human non-small-cell lung cancer cells in vitro.

AIM: To investigate the effects of 3,4,4'-trihydroxy-trans-stilbene (3,4,4'-THS), an analogue of resveratrol, on human non-small-cell lung cancer (NSCLC) cells in vitro.
METHODS: Cell viability of NSCLC A549 cells was determined by MTT assay. Cell apoptosis was evaluated using flow cytometry and TUNEL assay. Cell necrosis was evaluated with LDH assay. The expression of apoptosis- or autophagy-associated proteins was measured using Western blotting. The formation of acidic compartments was detected using AO staining, neutral red staining and Lysotracker-Red staining. LC3 punctae were analyzed with fluorescence microscopy.
RESULTS: Treatment with 3,4,4'-THS (10-80 μmol/L) concentration-dependently inhibited the cell viability. It did not cause cell necrosis, but induced apoptosis accompanied by up-regulation of cleavaged PARP, caspase3/9 and Bax, and by down-regulation of Bcl-2 and surviving. It also increased the formation of acidic compartments, LC3-II accumulation and GFP-LC3 labeled autophagosomes in the cells. It inhibited the mTOR-dependent pathway, but did not impair autophagic flux. 3,4,4'-THS-induced cell death was enhanced by the autophagy inhibitors 3-MA (5 mmol/L) or Wortmannin (2 μmol/L). Moreover, 3,4,4'-THS treatment elevated the ROS levels in the cells, and co-treatment with 3-MA further elevated the ROS levels. 3,4,4'-THS-induced apoptosis and autophagy in the cells was attenuated by NAC (10 mmol/L)
Conclusion: 3,4,4'-THS induces both apoptosis and autophagy in NSCLC A549 cells in vitro. Autophagy inhibitors promote 3,4,4'-THS-induced apoptosis of A549 cells, thus combination of 3,4,4'-THS and autophagy inhibitor provides a promising strategy for NSCLC treatment.