Investigating the redox state of stress-induced pancreatic tumor cells

Cancer cells can reprogram their metabolism supporting tumor formation and propagation, synergistically exploiting increased reactive oxygen species (ROS) production along with overexpression of ROS scavenger mechanisms. This leads to activation of several pro-tumorigenic cell signaling and survival pathways and altered intercellular signaling. Conversely, many chemo- and radio-therapy approaches are based, directly or indirectly, on ROS production to exert their cytotoxic activity. Redox status of the cell is thus a pivotal player in steering tumor cell metabolism toward proliferation or apoptosis. A clear understanding of its dysregulation is thus crucial in determining key targets for improving drug efficacy by means of combined therapy. In this view, both expression and post-translational modification of enzymes involved in redox metabolism must be considered. On these premises, we selected response of two pancreatic ductal adenocarcinoma cell lines differing to various stress inductors, to better define the antioxidant defenses put in place. Cell lines were first assessed for viability and ROS production after exposure to different concentrations of stress inductors. Those conditions leading to effective cell response (i.e. activation of anti-oxidant defense pathways with measurable variation in cell redox metabolism) were further investigated at different levels. A panel of genes involved in redox balance was assessed for their expression levels in stress-induced and not stress-induced cells by RT-qPCR. Catalytic activity of enzymes involved in redox status control was evaluated, along with a quali-quantitative determination of thiol, ROS, and carbonyl derivatives. Overall, this comprehensive investigation of metabolic reprogramming in stress-induced cells highlights the most relevant players in detoxification and chemoresistance and is useful as a general strategy to develop more effective combined therapies.