Effect of N-acetylcysteine on γ-radiation-induced cytotoxicity in human hepatocellular carcinoma cells

This study investigated the effect of N-acetylcysteine (NAC) against γ-radiation-induced cytotoxicity in human hepatocellular carcinoma (HepG2) cells. HepG2 Cells were incubated with 20 mM of NAC for 24 h prior to 6 Gy γ-irradiation. Apoptosis markers, such as caspase-3 and DNA fragmentation and oxidative stress markers, such as total nitrate/nitrite (NO(x)) and malondialdehyde (MDA) levels, superoxide dismutase (SOD) and glutathione (GSH) content were studied. Half of the lethal dose (LD50) of NAC on HepG2 cell viability was found to be 20 mM/mL after incubation for 48 h. Incubation of irradiated HepG2 cells with NAC inhibited γ-radiation-induced increases in caspase-3 activity and DNA fragmentation. Treatment with NAC before γ-radiation restored the changes induced by γ-irradiation by increasing SOD activity and GSH content in parallel with a decrease in MDA and NO(x) levels in HepG2 cells. NAC has a modulatory effect against γ-radiation-induced oxidative damage plausibly ascribable to its antioxidant/free radical scavenging ability.