Induction of Unfolded Protein Response by Tannic Acid Triggers Apoptosis in MDA-MB-231 Breast Cancer Cells

INTRODUCTION: Endoplasmic reticulum (ER) stress can reduce cell survival and enhances the apoptosis of cancer cells. Plant polyphenols like tannic acid trigger ER stress and apoptosis and therefore can be a novel agent for the treatment of cancer. In this study, we investigated the effect of tannic acid on survival, migration, colony formation, ER stress pathway, and apoptosis of the MDA-MB-231 breast cancer cells. METHODS: The MTT assay was performed to investigate the effect of tannic acid on the cell survival of breast cancer cells. We used the qPCR method to reveal the effect of tannic acid on the Bak, CHOP, ATF4, P21, MMP-2, and Bcl-2 expression. Also, colony formation, cell migration, and Hoechst staining assays were employed. RESULTS: The results of the MTT test showed that tannic acid reduced the cell survival rate. In the qPCR assay, we found that tannic acid decreased the expression levels of MMP-2, Bcl-2, ATF4, and CHOP genes, paradoxically, enhanced the expression of Bak and P21 genes. The colony formation and cell migration assays indicated that tannic acid significantly diminished breast cancer cell proliferation and migration, respectively. In the apoptosis assay, tannic acid increased the number of apoptotic cells. CONCLUSION: Tannic acid increases the rate of cell death but decreases viability and cell migration. Moreover, tannic acid induces apoptosis in breast cancer cells. Overall, our study demonstrates that tannic acid induces ER stress by increasing the genes which are playing role in ER stress pathway. These results show that tannic acid can be used as an effective agent for breast cancer treatment.