Somatostatin regulation of glycoprotein hormone and free subunit secretion in clinically nonfunctioning and somatotroph adenomas in vitro. 1991

A Klibanski, and J M Alexander, and H A Bikkal, and D W Hsu, and B Swearingen, and N T Zervas
Department of Medicine, Massachusetts General Hospital, Boston 02114.

There is increasing evidence that clinically nonfunctioning pituitary tumors produce and secrete glycoprotein hormone and/or free alpha- and beta-subunits. In addition, hypersecretion of free alpha-subunit occurs in up to 37% of patients with somatotroph adenomas. An understanding of glycoprotein hormone regulation is important in developing effective therapeutic strategies for patients with tumors associated with intact glycoprotein hormone and free subunit hypersecretion. We investigated glycoprotein hormone and free subunit secretion by somatostatin in primary dispersed cultures of pituitary tumor cells from 23 patients with pituitary adenomas. Fifteen tumors from patients with clinically nonfunctioning adenomas (group 1) and 8 tumors from patients with somatotroph adenomas and cosecretion of alpha-subunit (group 2) were studied. Cultures were incubated with control or somatostatin-supplemented media for 24 h. Media samples from group 1 tumors were assayed for intact glycoprotein hormones and free alpha- and beta-subunits secretion levels, while media samples from group 2 cultures were assayed for alpha-subunit and GH secretion levels. Significant (P less than 0.05-0.001) inhibition of secretion of 1 or more intact hormones and/or free subunits was found in 10 of the 15 group 1 tumors. SRIF[10(-7) M] suppressed intact gonadotropin secretion in 60% of FSH-producing tumors and 30% of LH-producing tumors. Media concentrations of FSH beta and LH beta were decreased in 31% and 50% of group 1 tumors, respectively, following somatostatin treatment in those tumors which secreted free beta-subunits. alpha-Subunit was secreted by 12 of the 15 tumors, but significant (P less than 0.02-0.01) inhibition by somatostatin was observed in only 2 tumors. In contrast, significant (P less than 0.05-0.001) inhibition of alpha-subunit in the somatotroph adenomas was found in 6 of the 8 tumors. Significant decreases in alpha-subunit were observed only in those tumors where GH was also significantly inhibited by somatostatin. We conclude that 1) somatostatin inhibits intact glycoprotein or free subunit secretion in the majority of clinically nonfunctioning pituitary tumors in vitro and 2) alpha-subunit secretion is suppressed in 17% and 69% of clinically nonfunctioning and somatotroph adenomas, respectively, consistent with a differential regulation of alpha-subunit by somatostatin in these two tumor types.

UI MeSH Term Description Entries
D007150 Immunohistochemistry Histochemical localization of immunoreactive substances using labeled antibodies as reagents. Immunocytochemistry,Immunogold Techniques,Immunogold-Silver Techniques,Immunohistocytochemistry,Immunolabeling Techniques,Immunogold Technics,Immunogold-Silver Technics,Immunolabeling Technics,Immunogold Silver Technics,Immunogold Silver Techniques,Immunogold Technic,Immunogold Technique,Immunogold-Silver Technic,Immunogold-Silver Technique,Immunolabeling Technic,Immunolabeling Technique,Technic, Immunogold,Technic, Immunogold-Silver,Technic, Immunolabeling,Technics, Immunogold,Technics, Immunogold-Silver,Technics, Immunolabeling,Technique, Immunogold,Technique, Immunogold-Silver,Technique, Immunolabeling,Techniques, Immunogold,Techniques, Immunogold-Silver,Techniques, Immunolabeling
D008875 Middle Aged An adult aged 45 - 64 years. Middle Age
D010911 Pituitary Neoplasms Neoplasms which arise from or metastasize to the PITUITARY GLAND. The majority of pituitary neoplasms are adenomas, which are divided into non-secreting and secreting forms. Hormone producing forms are further classified by the type of hormone they secrete. Pituitary adenomas may also be characterized by their staining properties (see ADENOMA, BASOPHIL; ADENOMA, ACIDOPHIL; and ADENOMA, CHROMOPHOBE). Pituitary tumors may compress adjacent structures, including the HYPOTHALAMUS, several CRANIAL NERVES, and the OPTIC CHIASM. Chiasmal compression may result in bitemporal HEMIANOPSIA. Pituitary Cancer,Cancer of Pituitary,Cancer of the Pituitary,Pituitary Adenoma,Pituitary Carcinoma,Pituitary Tumors,Adenoma, Pituitary,Adenomas, Pituitary,Cancer, Pituitary,Cancers, Pituitary,Carcinoma, Pituitary,Carcinomas, Pituitary,Neoplasm, Pituitary,Neoplasms, Pituitary,Pituitary Adenomas,Pituitary Cancers,Pituitary Carcinomas,Pituitary Neoplasm,Pituitary Tumor,Tumor, Pituitary,Tumors, Pituitary
D004305 Dose-Response Relationship, Drug The relationship between the dose of an administered drug and the response of the organism to the drug. Dose Response Relationship, Drug,Dose-Response Relationships, Drug,Drug Dose-Response Relationship,Drug Dose-Response Relationships,Relationship, Drug Dose-Response,Relationships, Drug Dose-Response
D006062 Gonadotropins Hormones that stimulate gonadal functions such as GAMETOGENESIS and sex steroid hormone production in the OVARY and the TESTIS. Major gonadotropins are glycoproteins produced primarily by the adenohypophysis (GONADOTROPINS, PITUITARY) and the placenta (CHORIONIC GONADOTROPIN). In some species, pituitary PROLACTIN and PLACENTAL LACTOGEN exert some luteotropic activities. Gonadotropin
D006801 Humans Members of the species Homo sapiens. Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000236 Adenoma A benign epithelial tumor with a glandular organization. Adenoma, Basal Cell,Adenoma, Follicular,Adenoma, Microcystic,Adenoma, Monomorphic,Adenoma, Papillary,Adenoma, Trabecular,Adenomas,Adenomas, Basal Cell,Adenomas, Follicular,Adenomas, Microcystic,Adenomas, Monomorphic,Adenomas, Papillary,Adenomas, Trabecular,Basal Cell Adenoma,Basal Cell Adenomas,Follicular Adenoma,Follicular Adenomas,Microcystic Adenoma,Microcystic Adenomas,Monomorphic Adenoma,Monomorphic Adenomas,Papillary Adenoma,Papillary Adenomas,Trabecular Adenoma,Trabecular Adenomas
D000328 Adult A person having attained full growth or maturity. Adults are of 19 through 44 years of age. For a person between 19 and 24 years of age, YOUNG ADULT is available. Adults
D000368 Aged A person 65 years of age or older. For a person older than 79 years, AGED, 80 AND OVER is available. Elderly
D013004 Somatostatin A 14-amino acid peptide named for its ability to inhibit pituitary GROWTH HORMONE release, also called somatotropin release-inhibiting factor. It is expressed in the central and peripheral nervous systems, the gut, and other organs. SRIF can also inhibit the release of THYROID-STIMULATING HORMONE; PROLACTIN; INSULIN; and GLUCAGON besides acting as a neurotransmitter and neuromodulator. In a number of species including humans, there is an additional form of somatostatin, SRIF-28 with a 14-amino acid extension at the N-terminal. Cyclic Somatostatin,Somatostatin-14,Somatotropin Release-Inhibiting Hormone,SRIH-14,Somatofalk,Somatostatin, Cyclic,Somatotropin Release-Inhibiting Factor,Stilamin,Somatostatin 14,Somatotropin Release Inhibiting Factor,Somatotropin Release Inhibiting Hormone

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