Previous studies have shown that cancer cells with defective autophagic apparatus accumulate DNA damage and deregulated ROS.36 We exploited γH2AX, a sensitive marker of DNA damage response, for assessing DNA damage in our system. Overexpression of miR-20a caused distinct γH2AX foci formation in MCF7 cells (Figure 5a). In line with this observation, immunoblotting revealed that miR-20a markedly increased the levels of γH2AX under normal and nutrient-starved conditions, whereas knocking down of endogenous miR-20a showed the opposite effect (Figure 5b). Comet assay and quantification of the tail moment (TM) confirmed that DNA damage was much more pronounced in miR-20a-transfected cells under nutrient starvation (Figure 5c). miR-20a also increased intracellular ROS levels in control and starved cells (Figure 5d).