Keratinocyte growth factor stimulates bronchial epithelial cell proliferation

tion is crucial to the maintenance of an intact airway surface and the preservation of host defenses. The factors that regulate AEC proliferation are not known. Keratinocyte growth factor (KGF), also known as FGF-7, is a member of the fibroblast growth factor family and a known epithelial cell mitogen. We studied the influence of KGF on the growth of cultured human bronchial epithelial cells and on bronchial cells of rats treated with KGF in vivo. First, we demonstrated the mRNA for the KGF receptor (KGFR) in both normal human bronchial epithelial (NHBE) cells and BEAS-2B cells (a human bronchial epithelial cell line). KGF caused a dose-dependent increase in DNA synthesis, as assessed by thymidine incorporation, in both cell types, with a maximal twofold increase in NHBE cells after 50 ng/ml KGF (P, 0.001). KGF also induced a doubling in NHBE cell number a