title: Glial-derived neurotropic factor and RET gene expression in normal human anterior pituitary cell types and in pituitary tumors.
abstract: Glial-derived neurotropic factor (GDNF) signaling is mediated through a 2-component system consisting of the so-called GDNF receptor-alpha (GFRalpha1), which binds to GDNF. This complex activates the tyrosine kinase receptor RET. In this paper we demonstrate GDNF, GFRalpha1, and RET mRNA and protein expression in the human anterior pituitary gland. Double immunohistochemistry of anterior pituitary sections showed GDNF immunoreactivity in more than 95% of somatotrophs and to a lesser extent in corticotrophs (20%); it was almost absent in the remaining cell types. Also, although more than 95% of somatotrophs were stained for RET, no positive immunostaining could be detected in other cell types. Furthermore, we have looked for GDNF and RET in human pituitary adenomas of various hormonal phenotypes. Strong positive immunostaining was found for c-RET in all of the GH-secreting adenomas screened as well as in 50% of ACTH-producing adenomas. Positive immunostaining for GDNF was found in all of the GH-secreting adenomas and in 10% of the corticotropinomas. Lastly, we found strong positive immunostaining for GFRalpha1 in 90% of the somatotropinomas and 50% of the corticotropinomas as well as in 1 of 8 prolactinomas and 1 of 13 nonfunctioning adenomas. All of the remaining pituitary tumors screened were negative for RET, GDNF, and GFRalpha1. This study indicates that GDNF may well be acting in the regulation of somatotroph cell growth and/or cell function in the normal human anterior pituitary gland. The expression of RET in all of the somatotropinomas and in 50% of the ACTH-producing tumors implies that GDNF and RET could be involved in the pathogenesis of pituitary tumors.
authors.affiliation: Department of Pathology, Hospital Universitario Virgen del Rocío, 41013 Sevilla, Spain.
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Japón
authors.forename: Angel G
authors.initials: AG
authors.lastname: Urbano
authors.forename: Carmen
authors.initials: C
authors.lastname: Sáez
authors.forename: Dolores I
authors.initials: DI
authors.lastname: Segura
authors.forename: Alfonso Leal
authors.initials: AL
authors.lastname: Cerro
authors.forename: Carlos
authors.initials: C
authors.lastname: Diéguez
authors.forename: Clara V
authors.initials: CV
authors.lastname: Alvarez
mesh_terms: D000236:Adenoma / Q000378:metabolism* / Q000473:pathology; D000324:Adrenocorticotropic Hormone / Q000378:metabolism; D015153:Blotting, Western; D029721:Drosophila Proteins; D005260:Female; D015870:Gene Expression; D051100:Glial Cell Line-Derived Neurotrophic Factor; D051097:Glial Cell Line-Derived Neurotrophic Factor Receptors; D019382:Human Growth Hormone / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D009414:Nerve Growth Factors; D009419:Nerve Tissue Proteins / Q000235:genetics* / Q000378:metabolism; D010903:Pituitary Gland, Anterior / Q000166:cytology / Q000502:physiology*; D010911:Pituitary Neoplasms / Q000378:metabolism* / Q000473:pathology; D011388:Prolactin / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism; D051096:Proto-Oncogene Proteins c-ret; D020794:Receptor Protein-Tyrosine Kinases / Q000235:genetics / Q000378:metabolism; D012016:Reference Values; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D029721:Drosophila Proteins; C495039:GDNF protein, human; C494987:GFRA1 protein, human; D051100:Glial Cell Line-Derived Neurotrophic Factor; D051097:Glial Cell Line-Derived Neurotrophic Factor Receptors; D009414:Nerve Growth Factors; D009419:Nerve Tissue Proteins; D011518:Proto-Oncogene Proteins; D019382:Human Growth Hormone; D000324:Adrenocorticotropic Hormone; D011388:Prolactin; D051096:Proto-Oncogene Proteins c-ret; D020794:Receptor Protein-Tyrosine Kinases; C416649:Ret protein, Drosophila