MODULATION OF THE UVA ACTIVATION OF HEME OXYGENASE, COLLAGENASE AND CYCLOOXYGENASE GENE-EXPRESSION BY EPIGALLOCATECHIN IN HUMAN SKIN CELLS

We have investigated the modifying effects of epigallocatechin, a majo r polyphenolic constituent of green tea, on ultraviolet-A-activated ge ne expression in human fibroblasts and keratinocytes using the stress responsive enzymes: haem oxygenase-1, interstitial collagenase and cyc looxygenase-2. Although epigallocatechin strongly reduced ultraviolet- A-induced haem oxygenase-l activation in skin-derived fibroblasts, the same compound activated collagenase and cyclooxygenase expression. In a keratinocyte cell Line, ultraviolet-A-mediated haem oxygenase-1 ove r-expression was ton and epigallocatechin failed to modulate it furthe r. In contrast to the results with fibroblasts, ultraviolet-A activati on of cyclooxygenase in keratinocytes was reduced by epigallocatechin. The results indicate that the effect of this green tea polyphenol on cellular stress responses is complex and may involve direct effects on signal transduction as well as changes that may be associated with it s antioxidant activity. (C) 1998 Federation of European Biochemical: S ocieties.