Effect of rebamipide on cell death induced by combined treatment of mild heat shock and quercetin in RGM-1 cells: a role for HSP70 induction.

The mechanism by which rebamipide inhibits cell death induced by combined treatment of mild heat shock and quercetin in RGM-1 cells was examined. Cells were incubated at 42 degrees C for 1 h with or without quercetin. Expression of HSP70 was detected by immunoblot analysis and cell viability was determined by the MTT method. Upon treatment of cells with heat shock in the presence of quercetin, cell viability was significantly decreased 24 h after heat shock, with strong inhibition of HSP70 expression. Rebamipide suppressed both cell death and a reduction in HSP70 induced by the combined treatment of heat shock and quercetin. The combination of heat shock and quercetin resulted in DNA fragmentation, but rebamipide managed to inhibit such fragmentation. The protective effect of rebamipide was eliminated by cycloheximide or actinomycin D. Based upon these findings, it was concluded that rebamipide inhibited cell death resulting from combined treatment of mild heat shock and quercetin. The protective action of rebamipide appears to be at least partially due to maintenance of the HSP70 level. Copyright 2002 S. Karger AG, Basel