Identification of human somatostatin receptor 2 domains involved in internalization and signaling in QGP-1 pancreatic neuroendocrine tumor cell line

Valeria Cambiaghi, Eleonora Vitali, Diego Morone, Erika Maria Peverelli, Anna Maria Spada, Giovanna Mantovani, Andrea Gerardo Antonio Lania

Research output: Contribution to journalArticle

Abstract

Somatostatin exerts inhibitory effects on hormone secretion and cell proliferation via five receptor subtypes (SST1–SST5), whose internalization is regulated by β-arrestins. The receptor domains involved in these effects have been only partially elucidated. The aim of the study is to characterize the molecular mechanism and determinants responsible for somatostatin receptor 2 internalization and signaling in pancreatic neuroendocrine QGP-1 cell line, focusing on the third intracellular loop and carboxyl terminal domains. We demonstrated that in cells transfected with somatostatin receptor 2 third intracellular loop mutant, no differences in β-arrestins recruitment and receptor internalization were observed after somatostatin receptor 2 activation in comparison with cells bearing wild-type somatostatin receptor 2. Conversely, the truncated somatostatin receptor 2 failed to recruit β-arrestins and to internalize after somatostatin receptor 2 agonist (BIM23120) incubation. Moreover, the inhibitory effect of BIM23120 on cell proliferation, cyclin D1 expression, P-ERK1/2 levels, apoptosis and vascular endothelial growth factor secretion was completely lost in cells transfected with either third intracellular loop or carboxyl terminal mutants. In conclusion, we demonstrated that somatostatin receptor 2 internalization requires intact carboxyl terminal while the effects of SS on cell proliferation, angiogenesis and apoptosis mediated by somatostatin receptor 2 need the integrity of both third intracellular loop and carboxyl terminal.

Original languageEnglish
Pages (from-to)146-157
JournalEndocrine
Volume56
Issue number1
DOIs
Publication statusPublished - 2017

Keywords

  • pancreatic neuroendocrine tumors
  • Somatostatin 2 receptor subtype
  • Somatostatin receptor
  • β-arrestins

ASJC Scopus subject areas

  • Endocrinology
  • Endocrinology, Diabetes and Metabolism

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