[Synergistic effect and its possible mechanisms of lidamycin in combination with TRAIL in NSCLC]

This study is to investigate the effect and its possible mechanisms of lidamycin (LDM) combined with tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) in human non-small cell lung cancer (NSCLC) cells. MTT assay was used to determine the growth inhibition of the two ingredients on H460 cells. Apoptosis was examined by Annexin V-FITC/PI staining, flow cytometry assay and DNA-specific dye Hoechst 33342 staining. The level of TRAIL receptor and apoptosis-associated protein expression was detected by Western blotting analysis. The results showed that the IC50 value of LDM and TRAIL for H460 cells was 4.603 x 10(-10) mol x L(-1) and 915.3 ng x mL(-1) respectively, but the IC50 value of LDM was 3.064 x 10(-11) mol x L(-1) and 1.611 x 10(-11) mol x L(-1) when different concentrations of LDM was combined with 50 and 100 ng x mL(-1) TRAIL respectively. And the CDI value was less than 1. The apoptosis ratios also increased in the combination group relative to the single-agent treatment and the untreated control. Furthermore, the induction of the cleavage of PARP and the activation of Caspase-3 and Caspase-8 by the combination were more effective than LDM or TRAIL alone. At last, the level of death receptor 5 (DR5) expressions increased in a dose-dependent manner and time-related pattern. The data indicate that LDM inhibits the growth of H460 cells in vitro. DR5 induction contributes to enhancement of TRAIL-induced apoptosis by LDM in human non-small lung cancer cells.