BACKGROUND: Lung cancer is one of the leading causes of mortality and morbidity. Viburnum grandiflorum is a medicinal herb known for its wide spectrum of pharmacological activities, but its anti-cancer properties against lung cancer cells have not been previously investigated. The present study elucidated the antitumor effect and associated mechanism of methanol extract of Viburnum grandiflorum extract (VGE) against lung cancer cells.

MATERIAL AND METHODS: The viability of H1650, HCC827, and H1299 cells was measured using MTT assay. Apoptosis and cell cycle progression were determined by flow cytometry using annexin-V/PI and JC-1 stains, respectively. The Lipofectamine Plus reagent (Invitrogen) was used for transfection of caspase-9 plasmid to H1650 and H1299 cells.

RESULTS: The results showed decreased H1650, HCC827, and H1299 cell viability by VGE, which occurred in a concentration- and time-dependent manner. The VGE treatment significantly increased the rate of apoptosis in H1650 (P<0.05) and H1299 (P<0.02) cells at 48 and 72 h. Treatment of H1650 and H1299 cells with 10 µM of VGE significantly enhanced the number of cells in sub-G1 phase. The VGE treatment cleaved pro-caspase-8/-9 and-3 in H1650 and HCC827 cells at 72 h. The VGE treatment of H1650 and HCC827 cells reduced Mcl-1 protein expression. Treatment of H1650 and HCC827 cells with VGE markedly decreased the level of p-Akt. However, dominant-negative caspase-9 (caspase-9 dN) plasmid transfection prevented the viability-inhibitory effect of VGE on H1650 and HCC827 cells. Treatment of H1650 and HCC827 cells with VGE increased levels of cytochrome c in the cytosol.

CONCLUSIONS: VGE inhibited lung carcinoma cell viability by apoptosis activation through a caspase-dependent pathway. Therefore, VGE is a potent anti-cancer agent against lung cancer cells.

Keywords: Molecular Conformation, proteolysis, Mitochondria, Myeloid Cell Leukemia Sequence 1 Protein, Phosphorylation, Viburnum