THE FGF FAMILY OF GROWTH-FACTORS AND ONCOGENES

The family of fibroblast growth factors (FGF) is the largest family of growth factors involved in soft–tissue growth and regeneration. The FGF family includes seven members that share a varying degree of homology at the protein level and appear to have a similar broad mitogenic spectrum. They are angiogenic and promote the proliferation of a variety of cells of mesodermal and neuroectodermal origin. Three members of the family–namely, K–FGF/HST, FGF–5, INT–2 are identified originally as oncogenes, while two additions, FGF–6 and keratinocyte growth factor (KGF), are isolated by sequence homology or factor purification and cloning. FGF was identified as an activity in pituitary extracts that stimulated the proliferation of 3T3 cells in mice. The two prototypes of basic and acidic protein structure, the FGF genes, and the expressions of FGF are also discussed. FGF consist of three exons, separated by two introns of variable length and FGF genes map on several chromosomes. The molecular regulation of FGF expression, FGF receptors, and their interaction with extracellular matrix is described. The oncogenic potential of FGF members and their involvement in tumors is also discussed. All possible mechanisms operating on the expression of FGFs and their receptors: transcriptional controls, posttranscriptional regulation involving alternative splicing, alternative translation starts resulting in proteins with different properties, and control affecting the secretion of these proteins are discussed. © 1992, Academic Press Inc.