Typhonium blumei extract inhibits proliferation of human lung adenocarcinoma A549 cells via induction of cell cycle arrest and apoptosis

Abstract

Typhonium blumei Nicolson & Sivadasan is a traditional Chinese medicinal herb endowing with detumescence, detoxification, anti-inflammation activities, and has been used as a folk prescription on anticancer in Taiwan. The purpose of this study is to investigate the inhibitory effect of Typhonium blumei (Tb) extract on the viability of different cancer cells and the apoptotic effect of this extract on A549 lung cancer cells. Human A549 cell line and other cancer cell lines were treated with different concentrations of Tb extract at different time intervals. Growth inhibition was determined by MTT assay. Apoptosis was detected by cell morphologic observation, cell cycle analysis, and immunoblot analysis on the expression of protein associated with cell death. GC-MS were used to determine the chemical constituents of this extract. The Tb extract had cytotoxicity toward A549 lung cancer cells (IC(50)=97.7 μg/ml), LNCaP prostate cancer cells (IC(50)=124.5 μg/ml) and MCF-7 breast cancer cells (IC(50)=125.8 μg/ml). Conversely, the adverse effects of Tb extract on normal embryonic lung fibroblast MRC-5 cells (IC(50)=245.5 μg/ml) and embryonic kidney fibroblast HEK293 cells (IC(50)=251.1 μg/ml) were comparatively low. Cytometric analysis results demonstrate that A549 cells were arrested at the G2/M phase by treatment with Tb extract. The extract induced A549 cell apoptosis via the mitochondrial pathway by down-regulating Bcl-2 and Bcl-xL protein expression, up-regulating Bax, Bad and Bak protein expression, and activating caspase-9 and caspase-3. Experimental results of bioactive compound analysis indicate that dibutyl phthalate, α-linolenic acid, phytol, campesterol, stigmasterol and β-sitosterol were the major bioactive ingredients of Tb extract. Although all these compounds had good anti-proliferative effects on A549 cells, campesterol (IC(50)=2.2 μM for 24h treatment) and β-sitosterol (IC(50)=1.9 μM for 24h treatment) displayed the greatest inhibitory activity. Experimental results of this study suggest that the Tb extract exerts potential anticancer activity through the growth inhibition and the apoptosis on A549 cells.