Coexpression of human somatostatin receptor-2 (SSTR2) and SSTR3 modulates antiproliferative signaling and apoptosis

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Sajad A War1, Ujendra Kumar

  • 1Faculty of Pharmaceutical Sciences, The University of British Columbia, Vancouver, BC, V6T 1Z3, Canada. ujkumar@mail.ubc.ca.

Journal of Molecular Signaling
|June 2, 2012
PubMed
Abstract

Insights

Somatostatin receptors SSTR2 and SSTR3 heterodimerize and signal via Gi-dependent pathways. This interaction inhibits cell proliferation through cytostatic and cytotoxic mechanisms, offering insights into tumor biology.

Area of Science:

  • Endocrinology
  • Molecular Cell Biology
  • Pharmacology

Background:

  • Somatostatin (SST) inhibits cell proliferation via five G protein-coupled receptors (SSTR1-5).
  • Receptor heterodimerization is critical for modulating SSTR signaling pathways.
  • This study focuses on human SSTR2/SSTR3 heterodimerization and its downstream effects.

Purpose of the Study:

  • To investigate human SSTR2/SSTR3 heterodimerization, internalization, and MAPK signaling.
  • To examine the impact of SST and specific agonists on cell proliferation and apoptosis.
  • To elucidate the signaling mechanisms of SSTR2/SSTR3 interactions.

Main Methods:

  • HEK-293 cells were cotransfected with SSTR2 and SSTR3.
  • Receptor localization, heterodimerization, and cAMP levels were assessed.
  • MAPK signaling (ERK1/2, p38), cell proliferation, and apoptosis were analyzed.

Main Results:

  • SSTR2 and SSTR3 heterodimerize at the plasma membrane and internalize upon agonist activation.
  • SST and agonists decreased cAMP levels and modulated ERK1/2 and p38 phosphorylation.
  • Gi-dependent inhibition of cell proliferation was observed, with increased PARP-1 and TUNEL staining, and induced p21/p27Kip1.

Conclusions:

  • SSTR2/SSTR3 signaling involves Gi-dependent inhibition of proliferation.
  • Mechanisms include cytostatic effects (p21/p27Kip1 induction) and cytotoxic effects (PARP-1, TUNEL).
  • Findings offer insights into SSTR-mediated signaling in tumor biology.

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