Different biological targets for resiniferatoxin and phorbol 12-myristate 13-acetate

The phorbol-related diterpene ester resiniferatoxin is at least 100-fold more inflammatory for the mouse ear than is the potent tumor promoter phorbol 12-myristate 13-acetate but is nonpromoting. We report here that resiniferatoxin is 100- to 1000-fold less active than is phorbol 12-myristate 13-acetate in in vitro assays with both chicken and mouse fibroblasts. These results suggest that resiniferatoxin and phorbol 12-myristate 13-acetate have different primary target sites (receptors) and provide further evidence that the fibroblast target may be homologous to that involved in promotion.