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Insulin-like growth factor 1 signaling in human gastrointestinal carcinoid tumor cells

Jamie Joseph Van Gompel1, Herbert Chen

  • 1Department of Surgery, University of Wisconsin Comprehensive Cancer Center, 600 Highland Avenue, Madison, WI 53792, USA.

Surgery
|January 20, 2005
PubMed

Insights

Activating the raf-1/MEK1 pathway blocks insulin-like growth factor 1 (IGF-1) effects on neuroendocrine hormone regulation in carcinoid tumors. This suggests raf-1/MEK1 activation is a potential therapeutic strategy for gastrointestinal carcinoid tumors.

Area of Science:

  • Oncology
  • Molecular Biology
  • Endocrinology

Background:

  • Insulin-like growth factor 1 (IGF-1) acts as an autocrine regulator in carcinoid tumors.
  • Blocking IGF-1 signaling is a potential therapeutic strategy for carcinoid syndrome.
  • The study investigates the role of parallel raf-1/MEK1 pathways in modulating IGF-1 signaling.

Purpose of the Study:

  • To determine if activating raf-1/MEK1 pathways can counteract IGF-1-mediated chromogranin A (CgA) maintenance.
  • To explore the therapeutic potential of raf-1/MEK1 pathway activation in gastrointestinal carcinoid tumors.

Main Methods:

  • Human gastrointestinal carcinoid tumor cells (BON) were treated with varying concentrations of IGF-1.
  • Raf-1/MEK1 activation was induced using an estrogen-inducible raf-1 vector.
  • Phosphorylation of downstream targets (p70s6, ERK1/2) and CgA levels were measured to assess pathway activation and hormone regulation.

Main Results:

  • IGF-1 and raf-1 pathways were successfully activated in BON cells, indicated by increased phosphorylation of p70s6 and ERK1/2.
  • IGF-1 treatment stimulated CgA release and maintained high intracellular CgA levels.
  • Activation of the raf-1/MEK1 pathway reversed IGF-1's effects, leading to depletion of intracellular CgA.

Conclusions:

  • Induction of the raf-1/MEK1 pathway effectively blocks IGF-1-mediated regulation of intracellular neuroendocrine hormones like CgA.
  • Raf-1/MEK1 pathway activation presents a promising therapeutic target for managing IGF-1-mediated cellular effects in gastrointestinal carcinoid tumors.

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