KERATINOCYTE GROWTH-FACTOR

Keratinocyte growth factor (KGF) is a member of the heparin-binding fi broblast growth factor family (FGF-7) with a distinctive pattern of ta rget-cell specificity. Studies performed in cell culture suggested tha t KGF was mitogenically active only on epithelial cells, albeit from a variety of tissues. In contrast, KGF was produced solely by cells of mesenchymal origin, leading to the hypothesis that it might function a s a paracrine mediator of mesenchymal-epithelial communication. Bioche mical analysis and molecular cloning established that the KGF receptor (KGFR) was a tyrosine kinase isoform encoded by the fgfr-2 gene. Many detailed investigations of KGF and KGFR expression in whole tissue an d cell lines largely substantiated the pattern initially perceived in vitro of mesenchymal and epithelial distribution, respectively. Moreov er, functional assays in organ culture and in vivo and studies of KGF regulation by sex sterorid hormones reinforced the idea that KGF acts predominantly on epithelial cells to elicit a variety of responses inc luding proliferation, migration and morphogenesis.