Correlation between DNA synthesis and glucosamine incorporation in human diploid fibroblasts stimulated by fibroblast growth factor and fetal calf serum.

Abstract

A 20 and 80% decrease of 3H-glucosamine incorporation was observed in resting human fibroblasts stimulated with fibroblast growth factor (FGF) and fetal calf serum (FCS), respectively. The decrease occurred as early as 15 min after stimulation. Inversely, DNA synthesis was increased 1 and 5 fold and cell number was increased 2 and 2.5 fold 72h later. 3H-glucosamine was incorporated in cell membrane glycopeptides (GP). Extracted from control or from cells exposed to FGF or FCS, GP have the same molecular weight and identical chemical constitution. The decrease of 3H-glucosamine incorporation caused by FGF and FCS appears to be related to the competitive binding between glucosamine-FGF and glucosamine-FCS components to GP, which probably constitute cell membrane receptors. A decline of 3H-glucosamine incorporation caused by FCS seems to result from the binding to cell-surface receptors (i.e., GP) of a large number of FCS components. The results suggest a correlation between cell growth rate and the density of growth-promoting molecules received by cells, since a large decrease of 3H-glucosamine incorporation corresponds to a high increase of DNA synthesis in cells exposed to FCS, which is a mixture of components with multiple effects.