Centaurea cyanus extracted 13-O-acetylsolstitialin A decrease Bax/Bcl-2 ratio and expression of cyclin D1/Cdk-4 to induce apoptosis and cell cycle arrest in MCF-7 and MDA-MB-231 breast cancer cell lines.

Natural products are considered recently as one of the source for production of efficient therapeutical agents for breast cancer treatment. In this study, a sesquiterpene lactone, 13-O-acetylsolstitialin A (13ASA), isolated from Centaurea cyanus, showed cytotoxic activities against MCF-7 and MDA-MB-231 breast cancer cell lines using standard 3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. To find the mechanism of action of cytotoxicity, annexin V/propidium iodide (PI) staining was performed for evaluation of apoptosis. This process was further confirmed by immunoblotting of anti- and proapoptotic, Bcl-2 and Bax, proteins. Cell cycle arrest was evaluated by measurement of fluorescence intensity of PI dye and further confirmed by immunoblotting of Cdk-4 and cyclin D1. Mitochondrial transmembrane potential (ΔΨm) and generation of reactive oxygen species (ROS) were measured using the JC-1 and DCFDA fluorescence probes, respectively. These experiments showed that 13ASA is a potent cytotoxic agent, which activates apoptosis-mediated cell death. In response to this compound, Bax/Bcl-2 ratio was noticeably increased in MCF-7 and MDA-MB-231 cells. Moreover, 13ASA induced cell cycle arrest at subG1 and G1 phases by decreasing protein levels of cyclin D1 and Cdk-4. It was done possibly through the decrease of ΔΨm and increase of ROS levels which induce apoptosis. In conclusion, this study mentioned that 13ASA inhibit the growth of MCF-7 and MDA-MB-231 breast cancer cell lines through the induction of cell cycle arrest, which triggers apoptotic pathways. 13ASA can be considered as a susceptible compound for further investigation in breast cancer study.