Levistolide A Induced Apoptosis Of Colon Cancer Cells And The Underlying Molecular Mechanisms

Colorectal cancer(CRC)ranks the third place of the death cause of malignant tumors in the world.With the deterioration of the environment,unhealthy eating habits and lifestyles,and the aging of the population,the morbidity and mortality rate are gradually increasing year by year.By far,the major therapeutic strategy for colon cancer is surgery combined with chemotherapy,but the resistance and side effects of the drugs seriously hinder the therapeutic efficacy.Therefore,it has become an urgent problem to be solved to develop new more effective and safer anti-cancer drugs.Natural compound extracted from traditional Chinese herb is the main source of new anti-cancer drugs.Screening anti-tumor drugs from natural herbal medicine has become a research hotspot.Levistolide A(LA)is a natural compound extracted from the roots of the traditional chinese medicinew Chuanxiong.However,there is no report about the anti-cancer mechanism of LA.This study aims to reveal the effects of LA on the proliferation and apoptosis of cancer cells,and to further illuminate the underlying molecular mechanism.The research contents mainly include the following three aspects:1.LA inhibited the growth of HCT116,HCT116 p53-/-,HT29,Hep G2 and Hela cells in a time-and dose-dependent manner for 24 h or 48 h,respectively.Low LDH release suggests that LA does not cause cell necrosis.With 5-Fu as the positive control,flow cytometry was used to analyze apoptosis of HCT116 and HCT116 p53-/-cells.Results showed that the apoptotic rate increased in a dose-dependent manner under the treatment of LA.We further detected the expression of apoptotic markers PARP and Caspase 3 and found that both of them were significantly up-regulated by LA in HCT116 cells.2.The ROS production in cells was quantified by flow cytometry,and the results showed that the ROS level was significantly increased by LA treatment.This effect was greatly diminished by the pretreatment of ROS scavenger NAC.Moreover,the LA-induced inhibition of cell growth and apoptosis were reversed by NAC.3.To explore the molecular mechanism of LA induced apoptosis of HCT116 cells.Western blot assay was used to detect ER stress-related proteins.Results showed that LA significantly activated ER stress and it was regulated via Bip/e IF2?/CHOP signaling pathway in HCT116 cells.Knock down of CHOP using si RNA largely abrogated LA-induced apoptosis.The inhibition of ROS could prevent the activation of ER stress evoked by LA.These results demonstrated that LA activated ER stress by increasing ROS.Our study demonstrates that LA significantly inhibits the cell viability and induces apoptosis of HCT116 colon cancer cells via ROS-mediated ER stress pathway.This study will provide a promising drug for the development of anticancer therapy.