title: PTHrP stimulated by the calcium-sensing receptor requires MAP kinase activation.
abstract: Increases in extracellular calcium concentration ([Ca(2+)](o)) stimulate from normal and malignant cells secretion of parathroid hormone-related protein (PTHrP), a major mediator of humoral hypercalcemia of malignancy. Because the calcium-sensing receptor (CaR) is a determinant of calcium-regulated hormone secretion, we examined whether HEK cells stably transfected with human CaR secreted PTHrP in response to CaR stimulation. Increases in [Ca(2+)](o) or neomycin and Gd(3+) all substantially increased PTHrP secretion in CaR-HEK cells but had no effect on nontransfected cells. CaR activation likewise increased PTHrP transcripts. PD-098059 and U-0126, inhibitors of the mitogen-activated protein kinase kinase MEK1/2, abolished CaR-stimulated secretion but had no effect on basal secretion. An inhibitor of p38 MAP kinase, SB-203580, also attenuated CaR-stimulated secretion. Western analysis revealed that CaR activation caused a robust increase in MEK1/2 and p38 MAP kinase phosphorylation. A Src family kinase inhibitor, PP2, blocked both basal and CaR-stimulated secretion. We conclude that CaR specifically mediates the effect of increasing [Ca(2+)](o) on PTHrP synthesis and secretion and that activated MEK1/2 and p38 MAP kinases are determinants of the CaR's stimulation of PTHrP secretion.
authors.affiliation: Endocrine-Hypertension Division and Membrane Biology Program, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115,USA. rmacleod@rics.bwh.harvard.edu
authors.forename: R John
authors.initials: RJ
authors.lastname: MacLeod
authors.forename: Naibedya
authors.initials: N
authors.lastname: Chattopadhyay
authors.forename: Edward M
authors.initials: EM
authors.lastname: Brown
mesh_terms: D000244:Adenosine Diphosphate / Q000494:pharmacology; D000814:Aniline Compounds / Q000494:pharmacology; D000841:Anisomycin / Q000494:pharmacology; D002118:Calcium / Q000819:agonists / Q000494:pharmacology; D002412:Cations / Q000494:pharmacology; D002460:Cell Line; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D007668:Kidney / Q000166:cytology; D048369:MAP Kinase Kinase 1; D048370:MAP Kinase Kinase 2; D020929:Mitogen-Activated Protein Kinase Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D044162:Parathyroid Hormone-Related Protein; D036361:Peptide Hormones / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D011493:Protein Kinase C / Q000037:antagonists & inhibitors; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D044169:Receptors, Calcium-Sensing; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic / Q000187:drug effects; D014162:Transfection; D048051:p38 Mitogen-Activated Protein Kinases; D019061:src-Family Kinases / Q000037:antagonists & inhibitors
chemical_list: D000814:Aniline Compounds; D002412:Cations; D004791:Enzyme Inhibitors; C111654:NPS R-467; C470121:PTHLH protein, human; D044162:Parathyroid Hormone-Related Protein; D036361:Peptide Hormones; D011500:Protein Synthesis Inhibitors; D044169:Receptors, Calcium-Sensing; D011956:Receptors, Cell Surface; D000244:Adenosine Diphosphate; D000841:Anisomycin; C482128:MAP2K2 protein, human; D011505:Protein-Tyrosine Kinases; D019061:src-Family Kinases; D017346:Protein Serine-Threonine Kinases; D011493:Protein Kinase C; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D048369:MAP Kinase Kinase 1; D048370:MAP Kinase Kinase 2; C482125:MAP2K1 protein, human; D020929:Mitogen-Activated Protein Kinase Kinases; D002118:Calcium