Aristolochia debilis Sieb. et Zucc. Induces Apoptosis and Reactive Oxygen Species in the HT-29 Human Colon Cancer Cell Line

In this study, we investigated the potential anticancer effect and mechanisms of action of a methanol extract from Aristolochia debilis Sieb. et Zucc (A. debilis) stems on human colon cancer cells (HT-29). A. debilis inhibited proliferation of HT-29 cells in dose-dependent and time-dependent manners as detected by the 1-(4,5-dimethylthiazol-2-yl)-3,5-diphenylformazan assay. A cell cycle analysis was performed via propidium iodide staining and flow cytometry. The A. debilis extract affected cell cycle progression by inducing sub-G(1) arrest. The reactive oxygen species (ROS) level was determined by dichlorofluorescin diacetate. A decrease in the mitochondrial membrane potential and inhibition of manganese superoxide dismutase in combination with the accumulation of ROS induced apoptosis. Reverse transcription-polymerase chain reaction and Western blot analyses were used to determine changes in the expression of mitochondria-dependent apoptosis markers (Bax and Bcl-2). Upregulation of Bax and corresponding downregulation of Bcl-2 expression as well as ROS production may be the critical mechanism through which A. debilis induced apoptosis in HT-29 cells.