The chemokine KC regulates HGF-stimulated epithelial cell morphogenesis

Hepatocyte growth factor (HGF) induces migration, proliferation, and branching in renal epithelial cells from the inner medullary collecting duct (mIMCD-3 cells). Microarray analysis after HGF stimulation of these cells revealed upregulation of the chemokine KC. We found that both the message and protein levels of KC are increased after HGF treatment and that mIMCD-3 cells express the KC receptor CXCR2. Treatment with KC results in stimulation of mIMCD-3 cell proliferation but has no effect on basal rates of cell migration or branching morphogenesis. In contrast to its known stimulatory effect on neutrophil migration, KC markedly inhibits HGF-mediated cell migration and branching morphogenesis, resulting in shorter tubules with fewer branch points. Examination of the mechanism of this effect reveals that KC does not alter phosphorylation of the c-met receptor or the initial activation of the MAPK or phosphoinositide 3-kinase (PI 3-K) signaling pathways. However, sustained activation of the PI 3-K pathway by HGF was inhibited by treatment with KC, and mimicking this effect by treatment with LY-294002 2 h after HGF stimulation reproduced the inhibition of HGF-stimulated branching morphogenesis. These data demonstrate that HGF-mediated KC production can act in an autocrine fashion to downregulate excessive branching and migration of renal epithelial cells in response to HGF, while still supporting cell proliferation. These characteristics may play a role in modulating the response to HGF during developmental tubule formation and/or during the repair of the tubular architecture following injury.