Chemokine Stromal Cell-Derived Factor 1α Induces Proliferation and Growth Hormone Release in GH4C1 Rat Pituitary Adenoma Cell Line through Multiple Intracellular Signals
- 28 October 2005
- journal article
- Published by American Society for Pharmacology & Experimental Therapeutics (ASPET) in Molecular Pharmacology
- Vol. 69 (2), 539-546
- https://doi.org/10.1124/mol.105.015255
Abstract
We used GH4C1 cells as a model to study the effects of the chemokine stromal cell-derived factor 1 (SDF1) in pituitary functions. In these cells, SDF1α induced proliferation and growth hormone secretion, suggesting a possible regulatory role for this chemokine at pituitary level. We evaluated the intracellular signaling involved in these effects: SDF1α increased cytosolic [Ca2+] and activated Pyk2, extracellular signal-regulated kinases 1 and 2 (ERK1/2), and large-conductance Ca2+-activated K+ channels (BKCa) channels. To correlate these intracellular effectors with the proliferative and secretory effects, we inhibited their activity using BAPTA-AM (Ca2+ chelator), 2′-amino-3′-methoxyflavone (PD98059; a mitogen-activated protein kinase kinase inhibitor), salicylate (Pyk2 inhibitor), and tetraethyl ammonium (K+ channel blocker). All of these compounds reverted SDF1α-induced proliferation, suggesting the involvement of multiple intracellular pathways. Conversely, only BAPTA-AM reverted growth hormone secretion. To identify a possible cross-talk and a molecular ordering among these pathways, we tested these antagonists on SDF1α-dependent activation of ERK1/2, Pyk2, and BKCa channels. From these experiments, we observed that the inhibition of [Ca2+]i increase or BKCa channel activity did not affect ERK1/2 activation by SDF1α; Pyk2 activation was purely Ca2+-dependent, not involving ERK1/2 or BKCa channels; and BKCa channel activity was antagonized by Pyk2 but not by ERK1/2 inhibitors. These data suggest that an SDF1α-dependent increase of [Ca2+]i activates Pyk2, which in turn regulates BKCa channel activity. Conversely, ERK1/2 activation is an independent phenomenon. In conclusion, we demonstrate that SDF1α causes both proliferation and growth hormone release from pituitary adenoma cells, suggesting that the activation of CXCR4 may represent a novel regulatory mechanism for growth hormone secretion and pituitary cell proliferation, which may contribute to pituitary adenoma development.Keywords
This publication has 31 references indexed in Scilit:
- Highly regionalized distribution of stromal cell‐derived factor‐1/CXCL12 in adult rat brain: constitutive expression in cholinergic, dopaminergic and vasopressinergic neuronsEuropean Journal of Neuroscience, 2003
- Characterization of the intracellular mechanisms mediating somatostatin and lanreotide inhibition of DNA synthesis and growth hormone release from dispersed human GH‐secreting pituitary adenoma cells in vitroClinical Endocrinology, 2003
- Signal Transduction of Physiological Concentrations of Vasopressin in A7r5 Vascular Smooth Muscle CellsOnline Journal of Public Health Informatics, 2002
- A Possible Role for CXCR4 and Its Ligand, the CXC Chemokine Stromal Cell-Derived Factor-1, in the Development of Bone Marrow Metastases in NeuroblastomaThe Journal of Immunology, 2001
- Chemokines and Their Receptors in the Central Nervous SystemFrontiers in Neuroendocrinology, 2001
- Stromal cell‐derived factor‐1α induces astrocyte proliferation through the activation of extracellular signal‐regulated kinases 1/2 pathwayJournal of Neurochemistry, 2001
- Genesis of pituitary adenomas: state of the art.Journal of Neuro-Oncology, 2001
- Characterization and visualization of [125I] stromal cell-derived factor-1α binding to CXCR4 receptors in rat brain and human neuroblastoma cellsJournal of Neuroimmunology, 2000
- Glial and Neuronal Cells Express Functional Chemokine Receptor CXCR4 and Its Natural Ligand Stromal Cell‐Derived Factor 1Journal of Neurochemistry, 1999
- HIV-1 Entry Cofactor: Functional cDNA Cloning of a Seven-Transmembrane, G Protein-Coupled ReceptorScience, 1996