Indomethacin and ibuprofen induce Hsc70 nuclear localization and activation of the heat shock response in HeLa cells

Abstract

It has been established that non-steroidal anti-inflammatory drugs (NSAIDs), such as sodium salicylate, sulindac, ibuprofen, and indomethacin, induce anti-inflammatory and anti-proliferative effects independent of cyclooxygenase. These cyclooxygenase-independent pharmacodynamic effects appear to regulate several signaling pathways involving proliferation, apoptosis, and heat shock response. However, the mechanisms of these actions remain an area of ongoing investigation. Hsc70 is a cytoplasmic chaperone protein involved in folding and trafficking of client proteins to different subcellular compartments, plays roles in signal transduction and apoptosis processes, and translocates to the nucleus following exposure to heat shock. Since NSAIDs induce some aspects of the heat shock response, we hypothesized that they may also induce Hsc70 nuclear translocation. Western immunoblotting and indirect cellular immunofluorescence showed that indomethacin and ibuprofen induce Hsc70 nuclear translocation at concentrations previously shown to induce HSF DNA-binding activity. Chemical inhibition of both p38(MAPK) and Erk42/44 had no effect on localization patterns. In addition, while indomethacin has been shown to behave as an oxidative stressor, the radical scavenging agent, N-acetyl cysteine, did not inhibit nuclear translocation. These results indicate that induction of the heat shock response by NSAIDs occurs at concentrations fivefold greater than those required to inhibit cyclooxygenase activity, suggesting a cyclooxygenase-independent mechanism, and in the presence or absence of kinase inhibitors and a free radical scavenger, suggesting independence of Erk42/44 or p38(MAPK) activities and intracellular oxidoreductive state.