Research Paper Volume 3, Issue 10 pp 1028—1038

Genome protective effect of metformin as revealed by reduced level of constitutive DNA damage signaling


Figure 1. Effect of metformin (MF) on the level of constitutive γH2AX expression in A549 cells. Exponentially growing A549 cells were left untreated (Ctrl) or treated with 1, 5 or 20 mM metformin for 48 h. Left panels present bivariate distributions of cellular DNA content versus intensity of γH2AX immunofluorescence (IF) detected with H2AX-Ser139 phospho-specific Ab in cells of these cultures; fluorescence of individual cells was measured by laser scanning cytometry (LSC) [76]. Based on differences in DNA content the cells were gated in G1, S and G2M phases of the cell cycle, as shown in the left panel, and the mean values of γH2AX IF for cells in each of these cell cycle phases by were obtained gating analysis. These mean values (+SD) are presented as the bar plots (right panel). The percent decrease in mean values of γH2AX expression of the metformin-treated cells with respect to the same phase of the cell cycle of the untreated cells is shown above the respective bars. The skewed dash line shows the upper level of γH2AX IF intensity for 97% of G1- and S- phase cells in Ctrl. The insets show cellular DNA content frequency histograms in the respective cultures.