Investigation of cytotoxic and genotoxic effects of mitochondrial derived peptide (MOTS-C) on human colon cancer cell line

Mitochondrial-derived peptide (MOTS-c) is a hormone encoded by mitochondrial DNA. It is reported that MOTS-c inhibits de novo purine biosynthesis and folate cycle in the cell. It has been shown that MOTS-c localizes to the nucleus and regulates nuclear gene expression in a 5'-adenosine monophosphate-activated protein kinase (AMPK)-dependent manner following metabolic stress. AMPK has been shown to be a potential therapeutic target for metabolic diseases, particularly cancer. In this study, we aimed to investigate the cytotoxic and genotoxic effects of MOTS-c on colorectal cancer cell line. In the study, different concentrations of MOTS-c and 5-Fluorouracil (5-FU) were applied to human colon cancer cell line (Caco-2) and non-tumorigenic colon epithelial cell line (FHC) at different time periods. The changes in the viability level of the cells after the treatments were determined by MTT analysis. The genoroxic effect of the compounds was demonstrated by single cell gel electrophoresis (Comet) analyzes. Apoptotic cell death level was determined by TUNEL staining. In addition, the effects of compounds on proteins acted role in apoptosis and autophagy processes were determined by Western blot analysis. MOTS-c application significantly decreased the viability of Caco-2 cells at 24 hours (p<0.05). After MOTS-c application, the DNA damage level and TUNEL positive cell count in the cells were similar to the control group. In contrast, administered 5-FU induced DNA damage and increased TUNEL positive cell count compared to the control group (p<0.05). While MOTS-c administration caused an increase in TSC2 and ULK1 protein levels in Caco-2 cells (p<0.05), it did not cause a significant change in Bax, Bcl-2, caspase-3, and p53 protein levels. In contrast, 5-FU administration increased p53 and Bax protein levels and decreased anti-apoptotic Bcl-2 expression. These results show that MOTS-c mediates cell death in Caco-2 cells by increasing ULK1 and TSC2 protein expressions.