Effects of transforming growth factor-beta and epidermal growth factor on clonal rat pulp cells

These factors influence proliferation and differentiation in various cell types. Their effects on a clonal cell line (RPC-C2A) having high ALPase activity were examined by assay of [3H]-thymidine incorporation and ALPase activity. Neither factor (at a dose of 0.5 ng/ml) altered the shape of the pulp cells. DNA synthesis was not affected by transforming growth factor-beta either in growing cells or in those nearly confluent, but epidermal growth factor, in doses ranging from 0.5 to 10 ng/ml, stimulated the incorporation of [3H]-thymidine in nearly confluent cells. Both factors inhibited ALPase activity in a dose-dependent manner. Indomethacin did not affect this inhibition, suggesting that this effect of growth factors may not be mediated by prostaglandin synthesis. Inhibitory effects of ALPase antagonists (L-phenylalanine, L-homoarginine, levamisole) were not affected by transforming growth factor-beta. Thus epidermal growth factor stimulates DNA synthesis and both transforming growth factor-beta and epidermal growth factor inhibit ALPase activity of clonal rat pulp cells, suggesting that both factors may act as regulators of biological function, including cell differentiation, in pulp cells.