Natural polyphenols are known for their variety of pharmacological properties including chemosensitizing of anticancer drugs. A dietary polyphenol, ferulic acid, was observed for the first time enhancing epirubicin-induced apoptosis in MDA-MB-231 human breast cells via the endoplasmic reticulum (ER) stress pathway. The combined index of 10 μM ferulic acid and epirubicin was less than 0.9, which indicates ferulic acid could significantly enhance the sensitivity of MDA-MB-231 cells to epirubicin. Flow cytometry analysis showed that apoptosis by epirubicin (1 μM) in MDA-MB-231 cells was enhanced by ferulic acid (10 μM). Western blot analysis demonstrated apoptosis was induced by increasing the expression of Bax, downregulating the level of Bcl-2 and activating caspase-3. Furthermore, it was observed that the synergism of ferulic acid (10 μM) and epirubicin (1 μM) increased the expression levels of the ER stress-related proteins such as PDI, IRE1α and PEPK while the results should be opposite after using the ER stress inhibitors. In conclusion, our results indicate that ferulic acid could be served as a potential officinal adjuvant for breast cancer treatment.

天然多酚因其多种药理特性（包括抗癌药的化学增敏作用）而闻名。首次观察到膳食多酚阿魏酸通过内质网（ER）应激途径增强了表柔比星诱导的MDA-MB-231人乳腺细胞凋亡。10μM阿魏酸和表柔比星的综合指数小于0.9，这表明阿魏酸可以显着增强MDA-MB-231细胞对表柔比星的敏感性。流式细胞仪分析表明，阿魏酸（10μM）增强了表柔比星（1μM）在MDA-MB-231细胞中的凋亡。蛋白质印迹分析表明凋亡是通过增加Bax表达，下调Bcl-2水平和激活caspase-3诱导的。此外，观察到阿魏酸（10μM）和表柔比星（1μM）的协同作用增加了ER应激相关蛋白（如PDI，IRE1α和PEPK）的表达水平，而使用ER应激抑制剂后结果相反。总之，我们的结果表明，阿魏酸可以作为潜在的乳腺癌佐剂。