Phyllanthus urinaria triggers the apoptosis and Bcl-2 down-regulation in Lewis lung carcinoma cells

Phyllanthus urinaria (P. urinaria), a widely used herb medicine, was tested for the anticancer effect in its water extract for the first time. The water extract of P. urinaria significantly decreased the number of Lewis lung carcinoma cells in a dose-and time-dependent manner as determined by MTT assay. However, the water extract of P. urinaria did not exert any cytotoxic effect on normal cells such as endothelial cells and liver cells. Result from flow cytometry revealed a dose-dependent increase of dead cells 24 hours after treating Lewis lung carcinoma cells with P. urinaria extract. The anticancer activity of P. urinaria extract was due to the apoptosis induced in Lewis lung carcinoma cells, which was demonstrated by DNA fragmentation analysis and increased caspase-3 activity. The apoptosis triggered by P. urinaria extract in Lewis lung carcinoma cells was associated with the down-regulation of Bcl-2 gene expression, but not with p53, p21 and Bax. Furthermore, the partial inhibition of P. urinaria-induced apoptosis in Lewis lung carcinoma cells by pretreatment with cyclosporin A, a mitochondria permeability transition pore inhibitor, suggesting that P. urinaria extract induced the apoptosis of Lewis lung carcinoma cells, at least in part, through a mitochondria-associated intrinsic pathway.