In vitro detection of glycoprotein production and secretion by human nonfunctioning pituitary adenomas.
This study, carried out on 9 nonfunctioning pituitary adenomas, was undertaken in order to evaluate the ability of these tumors to synthesize and release gonadotropins and/or free alpha-subunit (alpha-SU) of glycoproteins. The morphological study included electron microscopy and immunofluorescence analysis while hormone release was evaluated by the reverse hemolytic plaque assay (RHPA) and measurements in culture media. By electron microscopy in all tumors (6 null cell adenomas and 3 oncocytomas), it was possible to identify rough endoplasmic reticulum, Golgi apparatus and secretory granules. By immunofluorescence, 5 of 6 tumors were immunoreactive for one or more gonadotropin subunits; in particular, 5 adenomas were positive for alpha-SU and LH-beta, and 3 for FSH-beta. By the RHPA, about 1% of cells obtained from one single tumor formed plaques for LH-beta and alpha-SU while the remaining tumors were negative. Similarly, the study of media concentrations of LH, FSH and alpha-SU in 2 h culture revealed very low amounts of released hormones. In these experimental conditions no modification was observed after the addition of stimulatory agents such as TRH, GnRH and VIP. The present study clearly indicates that although the large majority of nonfunctioning tumors are positive for gonadotropins their secretory capacity is very low in both basal and stimulated conditions.
Saccomanno
K
K
Istituto di Scienze Endocrine, Ospedale Maggiore IRCCS, Milano, Italy.
Gil del Alamo
P
P
Bassetti
M
M
Reza-Elahi
F
F
Spada
A
A
D000236:Adenoma / Q000378:metabolism* / Q000648:ultrastructure; D003594:Cytoplasmic Granules / Q000648:ultrastructure; D004721:Endoplasmic Reticulum / Q000648:ultrastructure; D005455:Fluorescent Antibody Technique; D005640:Follicle Stimulating Hormone / Q000096:biosynthesis / Q000378:metabolism; D015292:Glycoprotein Hormones, alpha Subunit / Q000096:biosynthesis / Q000378:metabolism; D006056:Golgi Apparatus / Q000648:ultrastructure; D007987:Gonadotropin-Releasing Hormone / Q000494:pharmacology; D006065:Gonadotropins, Pituitary / Q000096:biosynthesis* / Q000378:metabolism; D013006:Growth Hormone / Q000096:biosynthesis / Q000378:metabolism; D006462:Hemolytic Plaque Technique; D006801:Humans; D007986:Luteinizing Hormone / Q000096:biosynthesis / Q000378:metabolism; D008854:Microscopy, Electron; D010911:Pituitary Neoplasms / Q000378:metabolism* / Q000648:ultrastructure; D011388:Prolactin / Q000096:biosynthesis / Q000378:metabolism; D013973:Thyrotropin-Releasing Hormone / Q000494:pharmacology; D014407:Tumor Cells, Cultured; D014660:Vasoactive Intestinal Peptide / Q000494:pharmacology
D015292:Glycoprotein Hormones, alpha Subunit; D006065:Gonadotropins, Pituitary; D007987:Gonadotropin-Releasing Hormone; D014660:Vasoactive Intestinal Peptide; D013973:Thyrotropin-Releasing Hormone; D011388:Prolactin; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone; D013006:Growth Hormone