High glucose promotes oxidative stress in pancreatic cancer cells

Objective: To investigate the effects of high glucose on the levels of reactive oxygen species (ROS) and antioxidant enzymes in pancreatic cancer cell line BxPC-3. Methods: After BxPC-3 cells were cultured in different concentrations of glucose, their intracellular ROS level determined using 2,7-dichlorodihydrofluorecein diacetate. The level of intracellular hydrogen peroxide (H₂O₂) was measured using H₂O₂ assay kit. The activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPX) were detected by different antioxidant enzyme analysis kits. The protein levels of SOD₁ and SOD₂ were measured by Western blot. The effect of small interfering RNA (siRNA) knockdown of SOD₂ on the level of H₂O₂ was also tested in pancreatic cancer cells. Results: The production of ROS and H₂O₂ was increased by glucose in a concentration-dependent manner (P<0.05). Addition of mannitol, an osmosis regulator, did not affect the levels of ROS and H₂O₂. Hyperglycemia could increase the activities of T-SOD and CAT as well as the protein expression of SOD₂ (P<0.05). SOD₂ siRNA was successfully transfected into BxPC-3 cells, resulting in the inhibition of SOD₂ protein expression (P<0.05). Down-regulation of SOD₂ significantly decreased hyperglycemia-induced H₂O₂ level. Conclusion: Hyperglycemia can increase ROS level in pancreatic cancer cells. The production of H₂O₂ is related to SOD₂ level.