Growth stimulation of rat calvaria osteoblastic cells by acidic fibroblast growth factor.
Purified acidic fibroblast growth factor (aFGF) from bovine brain stimulates the proliferation of calvaria-derived osteoblastic cells. Maximum stimulation, relative to corresponding controls, was seen at 0.2% serum (2- to 3-fold), and no stimulation was seen in the absence of serum or under serum replete conditions. The effect was dose-dependent with an ED50 of around 750 pg/ml (47 pM). aFGF (5 ng/ml) sustained the growth of calvaria cells in culture during multiple passages (72 days) at 0.2% serum. In DNA synthesis assays aFGF produced 2- to 4-fold stimulation; insulin-like growth factor I had a slight effect on DNA synthesis on its own, but enhanced the effect of aFGF 2-fold. In cells fully stimulated by epidermal growth factor (5-fold), aFGF had no further effect. Stimulation of DNA synthesis peaked at 5 ng/ml, while higher concentrations were inhibitory. Recombinant aFGF (bovine sequence) also stimulated cell proliferation (1.5-fold), and its potency was augmented by heparin (50 micrograms/ml), about 2-fold. Using simultaneous histochemical staining for alkaline phosphatase activity and [3H]thymidine nuclear uptake we found that aFGF stimulates DNA synthesis to the same extent in alkaline phosphatase-rich (osteoblastic) and alkaline phosphatase-poor (nonosteoblastic) cells. However, after cell division there is a significant decrease in PTH-responsive adenylate cyclase (2- to 3-fold) and in alkaline phosphatase levels (4- to 8-fold). These findings indicate that aFGF is mitogenic to rat calvaria osteoblastic cells, its action requires additional factors, and its growth stimulation is associated with a reduction in phenotypic expression.
Rodan
S B
SB
Department of Bone Biology and Osteoporosis Research, Merck Sharp & Dohme Research Laboratories, West Point Pennsylvania 19486.
Wesolowski
G
G
Thomas
K
K
Rodan
G A
GA
D000262:Adenylyl Cyclases / Q000378:metabolism; D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D004261:DNA Replication / Q000187:drug effects; D005346:Fibroblast Growth Factors / Q000494:pharmacology*; D007700:Kinetics; D010006:Osteoblasts / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology; D010281:Parathyroid Hormone / Q000494:pharmacology; D051381:Rats
D010281:Parathyroid Hormone; D005346:Fibroblast Growth Factors; D000469:Alkaline Phosphatase; D000262:Adenylyl Cyclases