Mechanism Study Of Seleno-β-Lactoglobulin On Apoptotic Effect In Breast Cancer Cells

The subjects of this study were human breast cancer MDA-MB-231 and MCF-7 cells.Seleno-β-lactoglobulin(Se-β-Lg)was synthesized using seleninic acid and β-lactoglobulin(β-Lg).In this study,MDA-MB-231 and MCF-7 cells were co-cultured with Se-β-Lg to determine the anti-tumor mechanism of Se-β-Lg on human breast cancer cells by a series of data.The MTT assay showed that Se-β-Lg was clearly cytotoxicity against breast cancer cells,in a concentration-dependent manner,but did not exhibit cytotoxicity to normal breast cells.The results showed that the half-maximal inhibitory concentrations(IC50)of Se-β-Lg were 40.84 μg/mL for MCF-7 cells and 46.04 μg/mL.Therefore,the Se-β-Lg concentrations of 20,40,and 80 μg/mL were selected for the follow-up experiments.Inverted microscope,scanning electron microscope and a confocal laser scanning microscope observed that the cells appeared typical apoptotic characteristics.With an increase in Se-β-Lg concentration,the proportion of apoptotic cells increased in a concentration-dependent manner compared with that in the control group.The proportion of apoptotic cells decreased after the addition of 10 mM N-acetyl-L-cysteine,a ROS inhibitor.Se-β-Lg-induced apoptosis caused G0/G1 phase arrest in MCF-7 and MDA-MB-231 cells.With an increase in concentration,the proportions of rhodamine 123-positive cells declined compared with those in the control groups.Tumor cells have a higher redox status than normal cells do.These results suggested that Se-β-Lg might induce apoptosis through mitochondrial-mediated internal apoptosis pathway.Se-β-Lg could increase of Bax/Bcl-2 ratio and release of Cytochrome C via the mitochondrial pathway in our study.When Cytochrome C forms a complex with apoptotic peptidase-activating factor 1(APAF1),caspase-9 is activated.Subsequently,cleaved-caspase-9 could active caspase-3 thereby initiating the apoptotic signaling pathway.Based on the results of our investigation,Se-β-Lg significantly inhibited the growth of human breast cancer MCF-7 and MDA-MB-231 cells in vitro,which suggests that Se-β-Lg can be developed as a new anticancer drug.