Oxymatrine diminishes the side population and inhibits the expression of β-catenin in MCF-7 breast cancer cells

Cancer stem cells (CSCs) play a critical role in both cancer initiation and relapse as they are resistant to most cytotoxic agents and able to proliferate indefinitely. The plant alkaloid oxymatrine has many biological activities including the ability to induce cell cycle arrest and apoptosis, which makes it a potentially useful agent for targeting cancer cells. In order to determine whether it has beneficial pharmacological properties to eradicate CSCs, we analyzed the effects of oxymatrine on MCF-7 breast cancer cells. Cancer stem-like cells' (side population, SP) identification and sorting were performed. The inhibitory effect of oxymatrine was evaluated on the sorted SP and non-SP cells. The results indicated that oxymatrine caused a dose-dependent reduction in the proliferation of MCF-7 cells and a decrease in SP cells. Wnt/beta-catenin signaling pathway was also examined by analyzing the expression of total beta-catenin and phosphorylated beta-catenin in cytoplasm, and the results showed that the growth inhibitory effects of oxymatrine treatment on MCF-7 cells may be due to the inhibition of SP and Wnt/beta-catenin signaling pathway. Further work is warranted to explore whether oxymatrine may be a useful novel therapeutic drug for targeting breast CSCs.