Prostaglandin E2 stimulates synthesis of insulin-like growth factor binding protein-3 in rat bone cells in vitro

Abstract

Prostaglandin E₂ is produced by bone cells and increases cyclic AMP in these cells. Like PTH and dibutyryl cyclic AMP, PGE₂ is a potent stimulator of IGF-I synthesis in cultured rat osteoblasts and inhibits DNA synthesis and type I procollagen gene expression. In addition, PGE₂ inhibits the response of the cells toward IGF-I after 1 day but not after 4 days of incubation. Rat calvaria osteoblasts constitutively release IGFBP_s into the culture medium, in particular IGFBP-2 and IGFBP-3. Like growth hormone, PGE₂ stimulates the accumulation of IGFBP-3. PGE₂ rapidly increases IGF-I and IGFBP-3 mRNA expression in calvaria cells, with a time course clearly different from that observed in response to growth hormone. Thus, PGE₂ modifies not only the synthesis of IGF-I but also that of IGFBP-3 in skeletal tissue.