Pyroglutamyl-histidyl-glycine, the endogenous colon mitosis inhibitor, regulates cyclic AMP level in non-tumorigenic colonic epithelial cells.

We have proposed that the mitosis inhibiting peptide, pyroGlu-His-Gly (pEHG), a colon-specific negative feedback regulator of cell proliferation, works through a G protein-coupled receptor (GPCR), as do many other pyroglutamyl-peptides.Non-tumorigenic YAMC (colon mucosa of Immorto mice), IMCE (Immorto-Min mouse hybrid) and human hepatoma (HepG2) cell lines were exposed to pEHG. cAMP concentrations were measured with a protein binding assay, mRNA levels with real-time PCR and Ca2+ concentration with an inverted fluorescence microscope on Fura-2/AM-loaded cells.pEHG (1 nM) increased the intracellular concentration of cAMP after 5-10 min in YAMC cells, but not in HepG2 cells. No effect was seen on cytosolic Ca2+, or in the expression of the proliferation and differentiation regulatory genes c-fos, egr-1 or fosB in YAMC or IMCE cells.pEHG stimulates the second messenger cAMP, but has no effect on intracellular Ca2+ or the gene expression of c-fos, egr-1 or fosB.