Abstract
Most reported breast cancer-associated deaths are directly correlated with metastatic disease. Additionally, the primary goal of treating metastatic breast cancer is to prolong life. Thus, there remains the need for more effective and safer strategies to treat metastatic breast cancer. Recently, more attention has been given to natural products (or phytochemicals) as potential anticancer treatments. This study aimed to investigate the synergistic effects of the combination of the phytochemicals chlorogenic acid and cinnamaldehyde (CGA and CA) toward inhibiting metastasis. The hypothesis was that CGA and CA in combination decrease the metastatic potential of breast cancer cells by inhibiting their invasive and migratory abilities as well as the induction of apoptosis via the downregulation of the Akt, disrupting its signal transduction pathway. To test this, wound-healing and Transwell™ Matrigel™ assays were conducted to assess changes in the migration and invasion properties of the cells; apoptosis was analyzed by fluorescence microscopy for Annexin V/propidium iodide; and immunoblotting and FACSort were performed on markers for the epithelial-to-mesenchymal transition status. The results show that CGA and CA significantly downregulated Akt activation by inhibiting phosphorylation. Consequently, increased caspase 3 and decreased Bcl2-α levels were observed, and apoptosis was confirmed. The inhibition of metastatic behavior was demonstrated by the attenuation of N-cadherin, fibronectin, vimentin, and MMP-9 expressions with concomitant increased expressions of E-cadherin and EpCAM. In summary, the present study demonstrated that CGA and CA in combination downregulated Akt activation, inhibited the metastatic potential, and induced apoptosis in different breast cancer cell lines.
Keywords:
breast cancer; chlorogenic acid; cinnamaldehyde; metastasis; natural products; phytochemicals.