Abstract: To investigate the molecular mechanism of apoptosis of human breast cancer MCF-7 cells induced by total saponins of Ornithogalum caudatum Ait (OCA-TS),MTT assay was used to detect the inhibitory effect of OCA-TS on the proliferation of MCF-7 cells and the changes of apoptosis morphology,membrane potential and apoptosis related protein content were observed.The results showed that OCA-TS could significantly inhibit the proliferation of human breast cancer MCF-7 cells (IC₅₀ was 93.17 g/mL),and the cells showed typical apoptotic morphology under electron microscopy.The results of flow cytometry showed that 48 hours after mca-7 cells were treated with different concentrations of OCA-TS,there was no significant change in mitochondrial membrane potential,Ca ²⁺ concentration and Cyt-C expression level;the activities of Caspase-8 and Caspase-3 were significantly increased,but the activities of Caspase-12 were not significantly changed,and the expression levels of Fas,FasL and FADD protein were significantly increased by Western blot.In conclusion,the apoptosis of MCF-7 cells induced by OCA-TS may be realized by activating death receptor pathway rather than by mitochondrial pathway and endoplasmic reticulum pathway.

Key words: Ornithogalum caudatum Ait, total saponin, human breast cancer MCF-7 cells, apoptosis, antitumor mechanism