COLLAGEN-BINDING GROWTH-FACTORS - PRODUCTION AND CHARACTERIZATION OF FUNCTIONAL FUSION PROTEINS HAVING A COLLAGEN-BINDING DOMAIN

0 The autocrine/paracrine peptide signaling molecules such as growth f actors have many promising biologic activities for clinical applicatio ns. However, one cannot expect specific therapeutic effects of the fac tors administered by ordinary drug delivery systems as they have limit ed target specificity and short half-lives in vivo. To overcome the di fficulties in using growth factors as therapeutic agents, we have prod uced fusion proteins consisting of growth factor moieties and a collag en-binding domain (CBD) derived from Clostridium histolyticum collagen ase. The fusion proteins carrying the epidermal growth factor (EGF) or basic fibroblast growth factor (bFGF) at the N terminal of CBD (CBEGF /CBFGF) tightly bound to insoluble collagen and stimulated the growth of BALB/c 3T3 fibroblasts as much as the unfused counterparts; CBEGF, when injected subcutaneously into nude mice, remained at the sites of injection for up to 10 days, whereas EGF was not detectable 24 h after injection. Although CBEGF did not exert a growth-promoting effect in vivo, CBFGF, but not bFGF, strongly stimulated the DNA synthesis in st romal cells at 5 days and 7 days after injection. These results indica te that CBD may be used as an anchoring unit to produce fusion protein s nondiffusible and long-lasting in vivo.