Metformin-induced and Mitochondrial Stress-mediated Apoptosis in Schizosaccharomyces pombe

Abstract

Metformin, a widely used first-line medication in the treatment of type II diabetes, has been proposed to have a second indication in the treatment of cancers and aging. However, its accounting mechanisms in cellular physiology were not clearly understood. Therefore, its cytotoxicity and underlying physiological mechanisms should be explained. Schizosaccharomyces pombe was evaluated as a single-cell cytotoxicity model and was treated with metformin and grown on YEL media at 30 °C and 180 rpm. 0,1-20 mM metformin caused dose-dependent apoptosis and necrosis demonstrated by using Annexin V-FITC/PI and DAPI staining. Surprisingly, metformin reduced ROS levels with stable antioxidant enzyme levels, but the mitochondrial transmembrane potential was significantly increased indicating a differential regulation by the dual character of metformin. In addition, a possible role can be attributed to Cnx1 in apoptotic cell death; which showed a dramatic increase in transcription, however, three other potential apoptotic genes, Rad9, Pca1, and Aif1 were stable. To conclude, the dual effect of metformin was clarified, and related cellular physiological effects with accompanying mechanisms (particularly Cnx1-mediated) were shown using S. pombe.