Mutation of somatostatin receptor type 5 in an acromegalic patient resistant to somatostatin analog treatment

Emilia Ballarè, Luca Persani, Andrea G. Lania, Marcello Filopanti, Enza Giammona, Sabrina Corbetta, Simona Mantovani, Maura Arosio, Paolo Beck-Peccoz, Giovanni Faglia, Anna Spada

Research output: Contribution to journalArticle

Abstract

Introduction of somatostatin analogs has greatly contributed to improving the prognosis of acromegaly. Although the majority of patients are effectively treated by these agents, resistance occurs in a subset of patients. So far, resistance to somatostatin has never been associated with mutations of the somatostatin receptor subtypes (sst2 and sst5) that inhibit GH secretion. Molecular analysis of genomic DNA from pituitary tumor and peripheral blood obtained from an acromegalic resistant to octreotide showed a somatic activating mutation of Gsα (Arg201Cys), no mutation in sst2, and one polymorphism (Pro109Ser) and one germ line mutation (Arg240Trp) in sst5. Wild-type (WT) and mutant sst5 PCR products were cloned and transfected into Chinese hamster ovary K1 cells. In Chinese hamster ovary K1 cells stably expressing mutant sst5, somatostatin-28 was less potent in inhibiting cyclic AMP levels than in WT cells. Proliferation of mutant cells exceeded that of WT by 50%. Moreover, somatostatin reduced cell growth and MAPK activity in WT but not in mutant cells in which the peptide even increased MAPK activity. We suggest that this mutation that abrogates the antiproliferative action of somatostatin and activates mitogenic pathways may be involved in the resistance to somatostatin treatment.

Original languageEnglish
Pages (from-to)3809-3814
Number of pages6
JournalJournal of Clinical Endocrinology and Metabolism
Volume86
Issue number8
DOIs
Publication statusPublished - 2001

ASJC Scopus subject areas

  • Biochemistry
  • Endocrinology, Diabetes and Metabolism

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