Pro-survival effects of repetitive low-grade oxidative stress are inhibited by simultaneous exposure to Resveratrol

V79 lung fibroblasts were subjected to repetitive oxidative stress in culture through exposures to 30 μM H2O2 for 4 weeks. Repetitively stressed cells were found to be significantly resistant to apoptosis-inducing agent such as ultraviolet radiation (UVR). Concurrent treatment with Resveratrol completely restored the normal apoptotic response after UVR. p38MAPK became dually phosphorylated during the stress period. Akt also became phosphorylated on Ser473 in cells subjected to repetitive oxidative stress. In these cells, NFκB p65 became phosphorylated and appreciable nuclear localization of p65 was observed. NFκB transcriptional activity also became augmented during repetitive stress. Treatment of the repetitively stressed cells concurrently with Resveratrol or SB203580, a p38MAPK inhibitor, robustly blocked activation of p38MAPK, NFκB transcriptional activity, phosphorylation and nuclear localization of p65, and Akt phosphorylation. Pre-exposure to short interfering RNA (si RNA) to p38MAPK, resulted in a blockage of the Akt and NFκB p65 phosphorylation. However, inhibition of Akt activity through PI3 kinase inhibitor LY294002 did not result in obstruction of p38MAPK phosphorylation by H2O2. Also, Resveratrol was effective as an antioxidant in counteracting a rise in reactive oxygen species (ROS) and p38MAPK activation by H2O2 was completely blocked by antioxidant N-acetyl cysteine (NAC). We conclude that Resveratrol acts as an antioxidant and completely reverses the anti-apoptotic effects of repetitive stress by blocking oxidative stress-induced p38MAPK activation which is the key regulatory step for the activation of down-stream survival elements Akt and NFκB.