P 153 - SIRT3 knockdown increases oxidative stress and sensitivity to cytotoxic treatments in SW620 cancer cells

Abstract

Sirtuin 3 (SIRT3) is the major deacetylase in mitochondria and is activated under oxidative stress conditions. SIRT3 regulates mitochondrial metabolism and the antioxidant response to lower reactive oxygen species (ROS) production. Thus, SIRT3 could allow cells to counteract the effect of anticancer therapies, which increase ROS levels. The aim of this study was to determine whether SIRT3 knockdown in colon cancer cells could increase oxidative stress and therefore make them more sensitive to cytotoxic treatments. A stable SIRT3 silencing in SW620 human cell line was achieved through a specific shRNA. Expression of antioxidant enzymes and mitochondrial proteins was analyzed, as well as protein levels by Western Blot and MnSOD enzymatic activity. Cells were also treated with oxaliplatin to study ROS production by Amplex Red®. SIRT3 silencing resulted in a decrease of both antioxidant enzymes and proteins related to mitochondrial function, as well as a reduction in MnSOD activity. Furthermore, SIRT3 knockdown produced a significant increase in ROS production, which was greater with oxaliplatin treatment. Overall, these results suggest that SIRT3 is a key factor regulating mitochondria under oxidative stress. SIRT3 knockdown could be a therapeutic strategy for colon cancer, since it improves the effectiveness of cytotoxic treatments.