Inhibition of epidermal growth factor-mediated ERK1/2 activation by in situ electroporation of nonpermeant [(alkylamino)methyl]acrylophenone derivatives.

The interruption of signaling cascades in intact cells through the introduction of nonpermeant compounds inferred by in vitro studies to specifically inhibit epidermal growth factor (EGF) receptor (EGF-R) function is described. Two nonpermeant [(alkylamino)methyl]acrylophenone derivatives, [(dimethylamino)methyl] acrylo-para-[(benzoylsulfonyl)-oxy]phenone and [(dimethylamino)-methyl]acrylo-para-[(hydroxy-benzoylsulfonyl++ +)-oxy]phenone, were introduced by in situ electroporation into mouse or rat fibroblasts growing on indium-tin oxide-coated glass. Cells were subsequently stimulated with growth factors and assessed for activation of a downstream target, the extracellular signal-regulated kinase (ERK1/2), by probing with specific antibodies. Electrodes and slides were configured to provide non-electroporated control cells side by side with the electroporated ones, both growing on the same type of indium-tin oxide-coated glass surface. Using this set-up, these compounds could inhibit EGF- but not platelet-derived growth factor (PDGF)-mediated ERK1/2 activation in vivo. These results demonstrate the potential of the in situ electroporation approach for the study of tyrosine kinase action using selective but nonpermeant inhibitors that would otherwise be ineffective in intact cells.