Catalogo Articoli (Spogli Riviste)

OPAC HELP

Titolo:
RELATIONSHIP BETWEEN PROTEIN-KINASE-C AND ADENYLYL-CYCLASE ACTIVITY IN THE REGULATION OF GROWTH-HORMONE SECRETION BY HUMAN PITUITARY SOMATOTROPHINOMAS
Autore:
LEI T; ADAMS EF; BUCHFELDER M; FAHLBUSCH R;
Indirizzi:
KOPFKLINIKUM,DEPT NEUROSURG,SCHWABACHANLAGE 6 D-91054 ERLANGEN GERMANY UNIV ERLANGEN NURNBERG,DEPT NEUROSURG D-8520 ERLANGEN GERMANY
Titolo Testata:
Neurosurgery
fascicolo: 3, volume: 39, anno: 1996,
pagine: 569 - 575
SICI:
0148-396X(1996)39:3<569:RBPAAA>2.0.ZU;2-Z
Fonte:
ISI
Lingua:
ENG
Soggetto:
INOSITOL PHOSPHOLIPID TURNOVER; CELL-CULTURE; BIOCHEMICAL CHARACTERISTICS; SIGNAL TRANSDUCTION; IN-VITRO; ADENOMAS; TUMORS; RELEASE; GH; GS;
Keywords:
GROWTH HORMONE; GSP ONCOGENES; PHOSPHATIDYLINOSITOL; PROTEIN KINASE C; SOMATOTROPHINOMAS;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Science Citation Index Expanded
Citazioni:
33
Recensione:
Indirizzi per estratti:
Citazione:
T. Lei et al., "RELATIONSHIP BETWEEN PROTEIN-KINASE-C AND ADENYLYL-CYCLASE ACTIVITY IN THE REGULATION OF GROWTH-HORMONE SECRETION BY HUMAN PITUITARY SOMATOTROPHINOMAS", Neurosurgery, 39(3), 1996, pp. 569-575

Abstract

OBJECTIVE: To determine the potential role of protein kinase C (PKC) and its relationship to adenylyl cyclase activity in controlling growth hormone (CH) secretion by human pituitary somatotrophinomas. METHODS: Twenty-eight somatotrophinomas were placed into cell culture, and the in vitro effects of the PKC activator 12-O-tetradecanoylphorbol 13-acetate (TPA) and the PKC inhibitor staurosporine on basal and GH-releasing hormone (GHRH)-stimulated GH secretion were examined. In addition, the influence of chronic exposure of cultured somatotrophinoma cellsto TPA on the rate of inositol 1,4,5-trisphosphate production was determined. Each tumor was assessed for the presence of gsp oncogenes, and thus constitutive adenylyl cyclase activity, by direct sequence analysis of polymerase chain reaction-generated deoxyribonucleic acid. CH secretory responses of tumors with and without these oncogenes were compared. RESULTS: TPA consistently stimulated GH secretion by cultured somatotrophinoma cells. There was no difference in response between somatotrophinomas with and without gsp oncogenes, and the effects did not correlate with the variable stimulation exerted by GHRH. Tumors in which GHRH had no significant effect nevertheless responded to TPA. In combination, TPA and GHRH exerted additive stimulation. TPA treatment of cultured somatotrophinoma cells eventually resulted in suppression of inositol 1,4,5-trisphosphate production, probably reflecting downregulation of membrane phosphatidylinositol hydrolysis, a second messenger system that also generates the endogenous PKC activator diacylglycerol. GHRH had no effect on phosphatidylinositol hydrolysis. In contrast to the effects of TPA, the PKC inhibitor staurosporine tended to reduce CH secretion, although this effect was not observed in all tumors examined. As with TPA, the effects of staurosporine did not correlate with presence or absence of gsp oncogenes. Furthermore, staurosporine did not reduce the stimulatory effects exerted by GHRH on CH secretion. CONCLUSION: These results demonstrate a role for the phosphatidylinositol-PKC second messenger cascade in controlling CH secretion by human pituitary somatotrophinomas. The results also show that the system operates relatively independent of intracellular adenylyl cyclase and, thus, protein kinase A.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 24/11/20 alle ore 22:43:08