RESUMO
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 αâ ¤ß3 integrin/focal adhesion kinase (FAK)/phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt) signaling transduction. Fibronectin, a physiologic ligand of αâ ¤ß3 integrin, was used to stimulate αâ ¤ß3 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 αâ ¤ and ß3 integrin and their co-localization. It also inhibited αâ ¤ß3 integrin downstream activation by suppressing the phosphorylation of FAK, PI3K, and Akt. Furthermore, oxymatrine prevented fibronectin-induced EMT and αâ ¤ß3 integrin/FAK/PI3K/Akt signaling activation. CONCLUSION: Our results revealed that oxymatrine effectively reversed EMT in breast cancer cells by depressing αâ ¤ß3 integrin/FAK/PI3K/Akt signaling. Thus, oxymatrine could be a potential therapeutic candidate with anti-metastatic potential for the treatment of breast cancer.
RESUMO
Triple-negative breast cancer (TNBC) is characterized by elevated metastasis, low survival, and poor response to therapy. Although many specific and effective agents for treating TNBC have been investigated, promising therapeutic options remain elusive. Here, we screened the inhibitory activities of three main components of Lithospermum erythrorhizon Sieb. et Zucc (shikonin, acetylshikonin, and ß,ß-dimethylacrylshikonin) on TNBC cells. The results revealed that shikonin potently decreased the viabilities of TNBC MDA-MB-231 and 4T1 cells but showed less cytotoxicity to normal mammary epithelial MCF-12A cells. Additionally, shikonin reversed the epithelial-to-mesenchymal transition (EMT) in MDA-MB-231 and 4T1 cells. Shikonin depressed cell migration and invasion, upregulated E-cadherin levels, downregulated N-cadherin, vimentin, and Snail levels, and reorganized the cytoskeletal proteins F-actin and vimentin. Shikonin reversed EMT by inhibiting activation of ß-catenin signaling through attenuating ß-catenin expression, nuclear accumulation, binding to T-cell factor consensus oligos, and transcription of its targeted EMT-related genes. Moreover, shikonin upregulated glycogen synthase kinase 3ß (GSK-3ß) levels, leading to enhanced phosphorylation and decreased levels of ß-catenin. Furthermore, shikonin administration significantly inhibited lung metastasis of MDA-MB-231 cells in NOD/SCID mice accompanied by low systemic toxicity. Histological analysis confirmed that shikonin elevated levels of E-cadherin, phosphorylated ß-catenin, and GSK-3ß, and decreased levels of vimentin and ß-catenin in pulmonary metastatic foci. These results indicated that shikonin potently inhibits TNBC metastasis by targeting the EMT via GSK-3ß-regulated suppression of ß-catenin signaling, which highlights the importance of shikonin as a potential candidate for novel anticancer therapeutics against TNBC.