EFFECT OF TYROSINE KINASE INHIBITION ON BASAL AND EPIDERMAL GROWTH FACTOR-STIMULATED HUMAN CACO-2 ENTEROCYTE SHEET MIGRATION AND PROLIFERATION

Mucosal healing requires enterocyte migration (restitution) supplement ed by proliferation. Proliferation and migration may be studied indepe ndently by thymidine uptake and proliferation-blocked cell migration u sing human Caco-2 enterocyte monolayers in culture. Since epidermal gr owth factor (EGF) promotes mucosal heating and the EGF receptor is a t yrosine kinase, we hypothesized that tyrosine kinases might therefore modulate enterocyte migration and proliferation. The tyrosine kinase i nhibitors genistein and 2,5-dihydroxymethylcinnamate, which block kina se ATP-binding and substrate-binding sites, respectively, were studied alone and with EGF. Proliferation was blocked with mitomycin. Althoug h each inhibitor decreased basal and EGF-stimulated monolayer expansio n when cell proliferation occurred, neither genistein nor 2,5-dihydrox ymethylcinnamate decreased migration when proliferation was blocked. H owever, each inhibitor prevented EGF stimulation of proliferation-bloc ked migration and thymidine uptake. More substantial inhibition of bas al proliferation by genistein correlated with increased protein-l in k ed DNA breaks, which may reflect nonspecific inhibition of DNA topoiso merase activity by genistein. The more specific 2,5-dihydroxymethylcin namate blocked changes in the alpha 2 integrin subunit organization wh ich may modulate EGF-stimulated migration. Antiproliferative effects o f tyrosine kinase inhibitors decrease basal monolayer expansion but tr ue basal enterocyte migration appears independent of tyrosine kinase r egulation. However, a specific tyrosi ne kinase-dependent modulation o f cell-matrix interaction inhibits EGF-stimulated migration. (C) 1994 Wiley-Liss, inc.