Search

Tanshinone IIA (T2A), a derivative of phenanthrenequinone and also the major active ingredient of Danshen, has been paid extensive attention as a promising cancer therapy for its potential anti-cancer activities. In this study, the apoptosis and autophagy of human prostate cancer PC-3 cells were observed after 5 μM T2A treatment, as well as their relevance. Mitochondrial-dependent apoptosis was firstly detected through morphological observation and biochemical analysis. Meanwhile, 5 μM T2A successfully triggered the autophagy of PC-3 cells, indicated by increased expression of Beclin1, and LC3 II. Validation experiments were conducted to further consolidate T2A's contribution to autophagy: Pretreatment with autophagy inhibitor 3-methyladenine (3-MA) provided protection against autophagy and enhanced T2A-induced apoptosis. Besides, the apoptosis suppressor z-VAD-fmk failed to facilitate the formation of autophagic vacuoles, which also proved the T2A-induced autophagy independent of apoptosis. Moreover, the reactive oxygen species (ROS) scavenger N-acetyl-L-cysteine (NAC) efficiently inhibited the expression of Beclin1, LC3-II, and cleaved caspase-3, which indicated apoptosis and autophagy with dependence on intracellular ROS production. Taken together, these results demonstrated that autophagy is the cytoprotective mechanism in this experimental system, and the ROS resulted from T2A treatment played a critical role in apoptosis and autophagy initiation.

Purpose : To investigate the anticancer activity of scopoletin against human prostate cancer. Methods : The anticancer activity of scopoletin was evaluated by 3-(4, 5-dimethylthiazol-2-yl)-2, 5- diphenyltetrazolium bromide (MMT) assay. Flow cytometry using propidium iodide and annexin V-FITC was employed to study apoptosis and cell cycle analysis. Hoechst 33258 staining was used to assess the effect of scopoletin on cell morphology and apoptotic body formation in human prostate carcinoma (LNCaP) cells via Florescence microscopy and finally Western blotting was used to evaluate the effect of scopoletin on cyclin D1 and cyclin B1 expressions. Results : Scopoletin induced a dose-dependent growth inhibition in LNCaP prostate cancer cells. It induced G2/M phase growth arrest and led to an increase in the sub-G0/G1 cell population after treatment with increasing doses compared to control cells, scopoletin treatment resulted in cell shrinkage along with membrane blebbing which are characteristic features of cell apoptosis. Approximately 15.45, 32.6 and 21.71 % of the cells underwent early apoptosis after treatment with 40, 80 and 100 μM of scopoletin respectively. Cyclin D expression diminished in a concentration-dependent manner when LNCaP cells were treated with different concentrations of scopoletin. Conclusion : These results reveal that scopoletin may be used as a natural chemotherapeutic agent against prostate cancer. Keywords : Prostate cancer, Apoptosis, Cell cycle analysis, Scopoletin, Flow cytometry, Fluorescence microscopy