Huachansu, containing cardiac glycosides, enhances radiosensitivity of human lung cancer cells.

AIM To assess radiosensitzing potential of huachansu (HCS) and delineate the underlying mechanisms. MATERIALS AND METHODS Lung cancer cell lines were exposed to HCS, radiation or both and subjected to survival assays, Western blots, apoptosis assay and immunocytochemical analysis. RESULTS HCS suppressed the viability of all three lung lines tested and enhanced radiosensitivity of H460 and A549 (wild-type p53) only with no effect on H1299 (p53 null) cells. HCS prolonged the presence of radiation-induced γH2AX foci and increased radiation-induced apoptosis. Western blots showed that HCS increased cleaved caspase-3 and cleaved poly-(ADP-ribose) polymerase (PARP) levels, as well as reducing BCL-2 and p53 protein levels in H460 cells. CONCLUSION HCS-enhanced radiosensitivity of human lung cancer lines appeared to be p53-dependent. Inhibition of DNA repair and increase in radiation-induced apoptosis may have served as underlying mechanisms. These data suggest that HCS may have potential to improve the efficacy of radiotherapy.