Novel function of prostaglandins as inducers of gene expression of HGF and putative mediators of tissue regeneration.

Prostaglandins (PGs) are multi-potent mediators for local tissue homeostasis and inflammatory reactions. Addition of PGs to cultures of human skin fibroblasts led to a marked induction of the production of hepatocyte growth factor (HGF). PGE1 and PGI2 analogues were the most potent in stimulating HGF production by over 50-fold; PGE2 and PGD2 were less potent. Western immunoblotting of conditioned medium from skin fibroblasts indicated that both PGE1, PGE2, and PGI2 analogues specifically induce synthesis of HGF with a M(r) of 85,000, but not smaller variant of HGF with a M(r) of 28,000. Consistent with the induction of HGF production, steady-state expression of HGF mRNA in fibroblasts was strongly induced by PGE1 and PGI2 analogues, but slightly by PGE2 and PGD2, thereby indicating that PGs induce HGF production through transcriptional activation of the HGF gene. PGE1, PGE2, PGI2 analogue also stimulated HGF production in MRC-5 human embryonic lung fibroblasts and vascular smooth muscle cells. As dibutyryl cyclicAMP (dbcAMP) and tetradecanoylphorbol 13-acetate (TPA), but not Ca(2+)-ionophore A23187 stimulated HGF production in skin fibroblasts, activation of protein kinase-A and protein kinase-C may be coupled to the stimulation of HGF production. Simultaneous addition of PGE1 and TPA or dbcAMP and TPA led to a synergistic enhancement of HGF production, whereas the simultaneous addition of PGE1 and dbcAMP failed to additively enhance HGF production.(ABSTRACT TRUNCATED AT 250 WORDS)