Chemoprotective effect of N-acetylcysteine (NAC) on cellular oxidative damages and apoptosis induced by nano titanium dioxide under UVA irradiation

The chemoprotective effect of N-acetylcysteine (NAC), a sulfhydryl-containing antioxidant, on nano titanium dioxide (nano-TiO2) induced oxidative stress and apoptosis in human keratinocyte (HaCaT) cells was assessed. HaCaT cells were pretreated with NAC followed by treatment with 200 μg/ml nano-TiO2, then exposed to ultraviolet A (UVA, 365 nm) for 1 h and cultured for 24 h. Intracellular reactive oxygen species (ROS) and nitric oxide (NO) formation, mitochondrial membrane potential (MMP), apoptosis and the content of the lipid peroxidation product malondialdehyde (MDA) were measured. Keratin 6 (K6) mRNA expression was also analyzed. The results showed that NAC strongly inhibited ROS and NO production in nano-TiO2 treated cells. The extent of lipid peroxidation was also decreased in the presence of NAC. In addition, NAC suppressed nano-TiO2 induced apoptosis and increased K6 mRNA expression. The results indicated that NAC could prevent oxidative stress and apoptosis induced by nano-TiO2 in HaCaT cells.