Purpose: Oxymatrine, an alkaloid extracted from the Chinese herb Sophora flavescens  Aiton, possesses anti-inflammatory, anti-immune, anti-hepatic fibrosis, and anti-cancer properties. However, the effects of oxymatrine on epithelial-mesenchymal transition (EMT) of breast cancer cells are still unclear.
Aim: The present study was performed to investigate whether oxymatrine reverses EMT in breast cancer cells and to explore the underlying molecular mechanisms.
Materials and methods: MTT assay was performed to evaluate cell viability. Wound-healing assay and transwell chamber assay were used to assess cell migration and invasion, respectively. Immunofluorescence and Western blot were used to study the expression of EMT-related molecules and α_Ⅴβ₃ integrin/focal adhesion kinase (FAK)/phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt) signaling transduction. Fibronectin, a physiologic ligand of α_Ⅴβ₃ integrin, was used to stimulate α_Ⅴβ₃ integrin signaling.
Results: Our results demonstrated that oxymatrine effectively suppressed the viability of MDA-MB-231 and 4T1 breast cancer cells, and oxymatrine showed less cytotoxicity on normal breast mammary epithelial MCF-10A cells. In addition, oxymatrine reversed EMT in the MDA-MB-231 and 4T1 cells at nontoxic concentrations. Oxymatrine significantly inhibited cell migration and invasion, downregulated the expression of N-cadherin, vimentin, and Snail in MDA-MB-231 and 4T1 cells, but upregulated the expression of E-cadherin in 4T1 cells. The mechanism revealed that oxymatrine decreased the expression of α_Ⅴ and β₃ integrin and their co-localization. It also inhibited α_Ⅴβ₃ integrin downstream activation by suppressing the phosphorylation of FAK, PI3K, and Akt. Furthermore, oxymatrine prevented fibronectin-induced EMT and α_Ⅴβ₃ integrin/FAK/PI3K/Akt signaling activation.
Conclusion: Our results revealed that oxymatrine effectively reversed EMT in breast cancer cells by depressing α_Ⅴβ₃ integrin/FAK/PI3K/Akt signaling. Thus, oxymatrine could be a potential therapeutic candidate with anti-metastatic potential for the treatment of breast cancer.
Keywords: oxymatrine, breast cancer, α_Ⅴβ₃ integrin, epithelial-mesenchymal transition