Bufalin induces apoptosis in vitro and has Antitumor activity against human lung cancer xenografts in vivo.

Bufalin has been shown to be effective against a variety of cancer cells, but its role in lung cancer has never been studied in an animal model. In this study, we evaluated bufalin effects in a human lung cancer cell line NCI-H460 both in vitro and in vivo. Bufalin caused significant cytotoxicity in NCI-H460 cells at a concentration as low as 1 μM. DNA condensation was observed in bufalin-treated cells in a dose-dependent manner. Mitochondrial membrane potential (ΔΨm ) was reduced and reactive oxygen species (ROS) were increased in bufalin-treated NCI-H460 cells. Levels of several proapoptotic proteins such as Fas, Fas-ligand, cytochrome c, apoptosis protease activating factor-1, endonuclease G, caspase-3 and caspase-9 were increased after bufalin treatment. At the same time, anti-apoptotic B-cell lymphoma 2 protein levels were reduced. Bufalin decreased glucose regulated protein-78 gene expression but increased growth arrest- and DNA damage-inducible 153 gene expression. Bufalin injected intraperitoneally in a dose-dependent manner reduced tumor size in BALB/C nu/nu mice implanted with NCI-H460 cells. Bufalin injection did not produce significant drug-related toxicity in experimental animals except at a high dose (0.4 mg kg-1 ). In conclusion, low concentrations of bufalin can induce apoptosis in the human lung cancer cell line NCI-H460 in vitro. Bufalin also reduced tumor size in mice injected with NCI-H460 cells without significant drug-related toxicity. These results indicate that bufalin may have potential to be developed as an agent for treating human non-small cell lung cancer.