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) supplemented by proliferation. Proliferation and migration may be studied independently by thymidine uptake and proliferation-blocked cell migration using human Caco-2 enterocyte monolayers in culture. Since epidermal growth factor (EGF) promotes mucosal healing and the EGF receptor is a tyrosine kinase, we hypothesized that tyrosine kinases might therefore modulate enterocyte migration and proliferation. The tyrosine kinase inhibitors genistein and 2,5-dihydroxymethylcinnamate, which block kinase ATP-binding and substrate-binding sites, respectively, were studied alone and with EGF. Proliferation was blocked with mitomycin. Although each inhibitor decreased basal and EGF-stimulated monolayer expansion when cell proliferation occurred, neither genistein nor 2,5-dihydroxymethylcinnamate decreased migration when proliferation was blocked. However, each inhibitor prevented EGF stimulation of proliferation-blocked migration and thymidine uptake. More substantial inhibition of basal proliferation by genistein correlated with increased protein-linked DNA breaks, which may reflect nonspecific inhibition of DNA topoisomerase activity by genistein. The more specific 2,5-dihydroxymethylcinnamate blocked changes in the alpha 2 integrin subunit organization which may modulate EGF-stimulated migration. Antiproliferative effects of tyrosine kinase inhibitors decrease basal monolayer expansion but true basal enterocyte migration appears independent of tyrosine kinase regulation. However, a specific tyrosine kinase-dependent modulation of cell-matrix interaction inhibits EGF-stimulated migration.