N-Acetyl Cysteine as a Novel Polymethyl Methacrylate Resin Component: Protection against Cell Apoptosis and Genotoxicity

Figure 6

Schematic model. The PMMA resin and the MMA monomer lead to the formation of increased levels of ROS after the depletion of GSH, which in turn activates the Nrf2-mediated antioxidant system and differential expression of antioxidative enzymes like SOD, GPx, and CAT, to protect cells from oxidative stress. However, oxidative stress beyond the capacities of cellular redox regulation causes oxidative DNA damage and cell cycle arrest, which subsequently upregulates p53 via ATM signaling and triggers intrinsic mitochondrial apoptosis. NAC alleviates PMMA-induced oxidative stress and protects cells from apoptosis by intracellular ROS scavenging, GSH replenishment, and direct chemical reaction to reduce the availability of a free monomer. This illustration summarizes the Discussion and is based on the current data and previous studies.