1alpha,25(OH)2-vitamin D3 inhibits HGF synthesis and secretion from MG-63 human osteosarcoma cells.
Several mesenchymally derived cells, including osteoblasts, secrete hepatocyte growth factor (HGF). 1alpha,25(OH)(2)-vitamin D(3) [1,25(OH)(2)D(3)] inhibits proliferation and induces differentiation of MG-63 osteoblastic cells. Here we show that MG-63 cells secrete copious amounts of HGF and that 1,25(OH)(2)D(3) inhibits HGF production. MG-63 cells also express HGF receptor (c-Met) mRNA, suggesting an autocrine action of HGF. Indeed, although exogenous HGF failed to stimulate cellular proliferation, neutralizing endogenous HGF with a neutralizing antibody inhibited MG-63 cell proliferation; moreover, inhibiting HGF synthesis with 1,25(OH)(2)D(3) followed by addition of HGF rescued hormone-induced inhibition of proliferation. Nonneutralized cells displayed constitutive phosphorylation of c-Met and the mitogen-activated protein kinases mitogen/extracellular signal-regulated kinase (MEK) 1 and extracellular signal-regulated kinase (Erk) 1/2, which were inhibited by anti-HGF antibody. Constitutive phosphorylation of Erk1/2 was also abolished by 1,25(OH)(2)D(3). Addition of HGF to MG-63 cells treated with neutralizing HGF antibody induced rapid phosphorylation of c-Met, MEK1, and Erk1/2. Thus endogenous HGF induces a constitutively active, autocrine mitogenic loop in MG-63 cells. The known antiproliferative effect of 1,25(OH)(2)D(3) on MG-63 cells can be accounted for by the concomitant 1,25(OH)(2)D(3)-induced inhibition of HGF production.
Chattopadhyay
Naibedya
N
Endocrine-Hypertension Division and Membrane Biology Program, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA. Naibedya@rics.bwh.harvard.edu
MacLeod
R J
RJ
Tfelt-Hansen
Jacob
J
Brown
Edward M
EM
D000906:Antibodies / Q000494:pharmacology; D002117:Calcitriol / Q000494:pharmacology*; D002454:Cell Differentiation / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D015870:Gene Expression; D017228:Hepatocyte Growth Factor / Q000096:biosynthesis* / Q000276:immunology / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D048369:MAP Kinase Kinase 1; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D010006:Osteoblasts / Q000473:pathology; D012516:Osteosarcoma / Q000378:metabolism* / Q000473:pathology; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D019859:Proto-Oncogene Proteins c-met / Q000235:genetics / Q000378:metabolism; D014407:Tumor Cells, Cultured
D000906:Antibodies; D017228:Hepatocyte Growth Factor; D019859:Proto-Oncogene Proteins c-met; D017346:Protein Serine-Threonine Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D048369:MAP Kinase Kinase 1; C482125:MAP2K1 protein, human; D020929:Mitogen-Activated Protein Kinase Kinases; D002117:Calcitriol