Determination of anticarcinogenic effects of mitochondrial-derived peptide (MOTS-C) in human breast cancer cell lines: An in vitro study

Aim: Mitochondrial-derived peptide (MOTS-c) is a peptide encoded by mitochondrial DNA and plays a role in cellular energy metabolism by activating AMP-activated protein kinase (AMPK). It is reported that AMPK is inhibited in many pathological conditions such as diabetes, aging, and cancer. New treatment approaches targeting AMPK may contribute to the treatment of these diseases. In this study, we aimed to explain the cytotoxic effects of MOTS-c on human breast cancer cell lines at the biochemical and molecular levels. Material and Method: In this study, applications of MOTS-c and reference drug 5-Fluorouracil (5-FU) on human breast cancer cell line and non-tumorigenic human breast epithelial cell line (MCF-7 and MCF10A, respectively) were performed in different time periods. Changes in cell viability were determined by 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays. The effects of the peptide on DNA damage and apoptotic cell death were investigated by single cell gel electrophoresis (Comet) method and TUNEL analysis. The effects of MOTS-c on genes acted role in apoptosis and autophagy pathways were determined by molecular analyses. Results: 72 hours after MOTS-c application, the viability of MCF-7 cells decreased significantly (p<0.05). It was determined that MOTS-c and 5-FU applications caused DNA damage in MCF-7 cells while both compounds did not cause DNA damage in MCF-10A cells. MOTS-c increased AMPK, TSC2, ULK1, and Beclin1 gene expressions in MCF-7 cells but did not change p53, pro-apoptotic Bax, and caspase-3 gene expressions. In contrast, 5-FU upregulated p53 expression in cells and increased Bax and caspase-3 gene expressions, suppressed Bcl-2 gene expression. Conclusion: These results showed that 5-FU caused apoptosis-induced cell death, while MOTS-c caused autophagy-mediated cell death resulting in activation of AMPK, TSC2, and ULK1. We think that MOTS-c can be used as a potential therapeutic candidate for breast cancer treatment in clinical applications after further studies.