Metastasis is a major cause of death in patients with breast cancer. In the process of cancer development, epithelial-mesenchymal transition (EMT) is crucial to promoting the invasion and migration of tumor cells. In a previous study, the role of resveratrol in migration and metastasis was investigated in MDA-MB-231 (MDA231) human breast cancer cells and a xenograft-bearing mouse model. Additionally, the related mechanism was explored. In the present study, in vitro Transwell assays showed that resveratrol can inhibit the migration of transforming growth factor (TGF)-β1-induced MDA231 cells in a concentration-dependent manner. An enzyme-linked immunosorbent assay (ELISA) showed that resveratrol can reduce the secretion of matrix metalloproteinase (MMP)-2 and MMP-9. Immunofluorescence was performed to confirm the expression of EMT-related markers. Immunofluorescence assays confirmed that resveratrol changed the expression of the EMT-related markers E-cadherin and vimentin. Western blot analysis demonstrated that resveratrol decreased the expression levels of MMP-2, MMP-9, Fibronectin, α-SMA, P-PI3K, P-AKT, Smad2, Smad3, P-Smad2, P-Smad3, vimentin, Snail1, and Slug, as well as increased the expression levels of E-cadherin in MDA231 cells. In vivo, resveratrol inhibited lung metastasis in a mouse model bearing MDA231 human breast cancer xenografts without marked changes in body weight or liver and kidney function. These results indicate that resveratrol inhibits the migration of MDA231 cells by reversing TGF-β1-induced EMT and inhibits the lung metastasis of MDA231 human breast cancer in a xenograft-bearing mouse model.

Curcumin, a natural compound derived from the turmeric rhizome Curcuma longa Linn, has anticancer and chemoresistance reduction biological activities. We evaluated the efficacy of curcumin in sensitizing chemotherapy drugs through regulation of Bcl-2-mediated apoptosis in breast cancer stem-like cells (BCSCs). Cell survival was measured using MTT assay. Apoptosis-related proteins were observed using western blot analysis. Apoptosis was detected with flow cytometric analysis and by Hoechst 33258 staining. The mitochondrial membrane potential was observed with flow cytometric analysis. The ability of BCSCs to propagate decreased gradually along the passages and was completely lost at the fifth passage [0.1 μmol/L mitomycin C (MMC) with 5 μmol/L curcumin in MCF-7 and 0.5 μmol/L MMC with 5 μmol/L curcumin in MDA-MB-231 cells]. Curcumin combined with MMC treatment significantly decreased the levels of antiapoptotic Bcl-2 and Bcl-w expression, increased the levels of proapoptotic Bax, Bak, Bad, Bik, and Bim expression, and activated caspase-3 and caspase-9 in MCF-7 BCSCs. In the presence of Bcl-2 siRNA, the apoptosis rate increased by 15% in cells treated with curcumin and MMC. The mitochondrial membrane potential decreased by approximately 20% in MCF-7 BCSCs undergoing the combination treatment of curcumin and MMC. The combination-induced decrease in Bcl-2 was regulated by the presence of the Wnt-specific inhibitor PFK115-584 and PI3k inhibitor LY294002. Our study indicates that curcumin might represent a novel therapeutic agent for treating breast cancer chemoresistance induced by MMC.

Triple-negative breast cancer (TNBC) is a refractory type of breast cancer that does not yet have clinically effective drugs. The aim of this study is to investigate the synergistic effects and mechanisms of resveratrol combined with cisplatin on human breast cancer MDA-MB-231 (MDA231) cell viability, migration, and invasion in vivo and in vitro. In vitro, MTS assays showed that resveratrol combined with cisplatin inhibits cell viability as a concentration-dependent manner, and produced synergistic effects (CI < 1). Transwell assay showed that the combined treatment inhibits TGF-β1-induced cell migration and invasion. Immunofluorescence assays confirmed that resveratrol upregulated E-cadherin expression and downregulated vimentin expression. Western blot assay demonstrated that resveratrol combined with cisplatin significantly reduced the expression of fibronectin, vimentin, P-AKT, P-PI3K, P-JNK, P-ERK, Sma2, and Smad3 induced by TGF-β1 (p < 0.05), and increased the expression of E-cadherin (p < 0.05), respectively. In vivo, resveratrol enhanced tumor growth inhibition and reduced body weight loss and kidney function impairment by cisplatin in MDA231 xenografts, and significantly reduced the expressions of P-AKT, P-PI3K, Smad2, Smad3, P-JNK, P-ERK, and NF-κB in tumor tissues (p < 0.05). These results indicated that resveratrol combined with cisplatin inhibits the viability of breast cancer MDA231 cells synergistically, and inhibits MDA231 cells invasion and migration through Epithelial-mesenchymal transition (EMT) approach, and resveratrol enhanced anti-tumor effect and reduced side of cisplatin in MDA231 xenografts. The mechanism may be involved in the regulations of PI3K/AKT, JNK, ERK and NF-κB expressions.

Background/Aim: The synergistic combinations of natural products have long been the basis of Traditional Chinese herbal Medicine formulas. In this study, we investigated the synergistic effects of a combination of berberine and evodiamine against human breast cancer MCF-7 cells in vitro and in vivo, and explored its mechanism. Materials and Methods: Cell survival was measured using the MTT assay. Apoptosis-related proteins were observed using western blot analysis. Apoptosis was detected with flow cytometric analysis and by Hoechst 33258 staining. Tumor xenografts were used in vivo. Results: Compared to berberine or evodiamine treatments alone, the combination treatment of berberine (25 μM) and evodiamine (15 μM) synergistically inhibited the proliferation of MCF-7 cells in a time-dependent manner and resulted in the G₀/G₁ phase accumulation of cells that exhibited increased expression levels of the CDK inhibitors p21 and p27 with a concomitant reduction in the expression levels of cell-cycle checkpoint proteins cyclin D1, cyclin E, CDK4, and CDK6. Furthermore, the combination treatment induced apoptosis that was accompanied by increased expression levels of p53 and Bax, reduced expression levels of Bcl-2, activation of caspase-7, and caspase-9, and the cleavage of PARP. The combination of berberine and evodiamine synergistically inhibited tumor growth in vivo in MCF-7 human breast cancer xenografts. Conclusion: Combination of berberine and evodiamine acts synergistically to suppress the proliferation of MCF-7 cells by inducing cell cycle arrest and apoptosis, illustrating the potential synergistic and combinatorial application of bioactive natural products.

Background. Formononetin, an active ingredient isolated from the traditional Chinese medicinal herb Astragalus membranaceus, has anticancer and chemoresistance-reducing biological activities. We evaluated the efficacy of formononetin in improving the tumoricidal effect of everolimus by suppressing the mTOR pathway in breast cancer cells. Methods. Cell survival was assessed using an MTT assay. Apoptosis was detected using flow cytometry. Proteins related to the mTOR pathway were detected and assessed using real-time PCR and Western blot analysis. Results. The results showed that formononetin enhances the efficacy of everolimus in suppressing breast cancer cell growth both in vitro and in vivo. The combination of formononetin and everolimus resulted in a 2-fold decrease in tumor volume and a 21.6% decrease in cell survival. The apoptosis ratio in cells treated with formononetin and everolimus increased by 27.9%. Formononetin and everolimus also inhibited the expression of p-mTOR and p-P70S6K and increased the expression of PTEN and p-4EBP-1. Notably, formononetin alone inhibited p-Akt expression but not everolimus. Conclusions. Formononetin enhances the tumoricidal effect of everolimus by inhibiting the activity of Akt.