title: Localization of carboxyl ester lipase in human pituitary gland and pituitary adenomas.
abstract: Carboxyl ester lipase (CEL) is an enzyme that hydrolyzes a wide variety of lipid substrates, including ceramides, which are known to show inhibitory regulation of pituitary hormone secretion in experimental models. Because no studies on CEL expression in human pituitary and pituitary adenomas have been reported in the literature, we investigated CEL expression in 10 normal pituitary glands and 86 well-characterized pituitary adenomas [12 FSH/LH cell, 17 α-subunit/null cell, 6 TSH cell, 21 ACTH cell, 11 prolactin (PRL) cell, and 19 GH cell adenomas] using IHC, immunoelectron microscopy, Western blotting, and quantitative RT-PCR. In normal adenohypophysis, CEL was localized in GH, ACTH, and TSH cells. In adenomas, it was mainly found in functioning GH, ACTH, and TSH tumors, whereas its expression was poor in the corresponding silent adenomas and was lacking in FSH/LH cell, null cell, and PRL cell adenomas. Ultrastructurally, CEL was localized in secretory granules close to their membranes. This is the first study demonstrating CEL expression in normal human pituitary glands and in functioning GH, ACTH, and TSH adenomas. Considering that CEL hydrolyzes ceramides, inactivating their inhibitory function on pituitary hormone secretion, our findings suggest a possible role of CEL in the regulation of hormone secretion in both normal and adenomatous pituitary cells.
authors.affiliation: Department of Pathology, Ospedale di Circolo, Varese, Italy. anapat@ospedale.varese.it
authors.forename: Stefano
authors.initials: S
authors.lastname: La Rosa
authors.forename: Davide
authors.initials: D
authors.lastname: Vigetti
authors.forename: Claudia
authors.initials: C
authors.lastname: Placidi
authors.forename: Giovanna
authors.initials: G
authors.lastname: Finzi
authors.forename: Silvia
authors.initials: S
authors.lastname: Uccella
authors.forename: Moira
authors.initials: M
authors.lastname: Clerici
authors.forename: Barbara
authors.initials: B
authors.lastname: Bartolini
authors.forename: Ileana
authors.initials: I
authors.lastname: Carnevali
authors.forename: Marco
authors.initials: M
authors.lastname: Losa
authors.forename: Carlo
authors.initials: C
authors.lastname: Capella
mesh_terms: D000236:Adenoma / Q000201:enzymology*; D002460:Cell Line; D045744:Cell Line, Tumor; D006801:Humans; D007150:Immunohistochemistry; D008049:Lipase / Q000096:biosynthesis*; D016253:Microscopy, Immunoelectron; D010902:Pituitary Gland / Q000201:enzymology*; D010911:Pituitary Neoplasms / Q000201:enzymology*; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: C054621:CEL protein, human; D008049:Lipase