Signaling mechanisms of glucagon-like peptide 2-induced intestinal epithelial cell proliferation

Background. Glucagon-like peptide 2 (GLP-2) stimulates intestinal epithelia l growth with high potency and specificity. However, the intracellular sign aling pathways responsible for the growth-stimulatory action of GLP-2 are n ot clearly understood. Here we report possible signaling pathways mediating GLP-2's proliferative actions in the human intestinal epithelial cell line Caco-2. Materials and methods. Caco-2 cells were subcultured under serum-deprived c onditions in the presence or absence of GLP-2 (10 mu M) and varying concent rations of inhibitors of three candidate kinases: genistein, a global tyros ine kinase inhibitor; LY294002, a phosphatidylinositide (PI) 3-kinase inhib itor; and PD 098059, a mitogen-activated/extracellular signal-regulated kin ase (MEK) inhibitor. Proliferation was assessed using [H-3]thymidine incorp oration. Relative abundance of the phosphorylated forms of two specific mit ogen-activated protein kinases (MAPKs), ERK1 and ERK2, was assessed by West ern blotting. Results. GLP-2-treated cells demonstrated a greater than 10-fold increase i n proliferation. This response was inhibited by genistein, LY294002, and PD 098059 in a dose-dependent fashion. A significantly greater abundance of t he phosphorylated forms of both ERK-1 and ERK-2 was present in cells within 5 min of treatment with GLP-2. Conclusions. GLP-2 stimulates the proliferation of Caco-2 cells in vitro. T his increase in Caco-2 proliferation in response to GLP-2 may be due, at le ast in part, to the involvement of both the PI 3-kinase and the MAPK pathwa ys. (C) 2000 Academic Press.