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Insulin receptor substrates mediate distinct biological responses to insulin-like growth factor receptor activation

S A Byron1, K B Horwitz, J K Richer

  • 1Department of Pharmacology, University of Minnesota Cancer Center, Minneapolis, MN 55455, USA.

British Journal of Cancer
|October 18, 2006
PubMed

Insights

Insulin receptor substrate-1 (IRS-1) and IRS-2 mediate distinct effects in breast cancer cells. IRS-1 promotes proliferation, while IRS-2 enhances motility, both downstream of the insulin-like growth factor receptor (IGF-IR).

Area of Science:

  • Molecular Biology
  • Cancer Research
  • Cell Signaling

Background:

  • The type I insulin-like growth factor receptor (IGF-IR) plays a role in cancer progression, influencing proliferation and metastasis.
  • Adaptor proteins downstream of IGF-IR signaling are crucial for mediating specific cancer phenotypes.
  • Understanding the distinct roles of these adaptor proteins is key to targeting IGF-IR pathways effectively.

Purpose of the Study:

  • To investigate whether insulin receptor substrate-1 (IRS-1) and insulin receptor substrate-2 (IRS-2) mediate different biological effects in breast cancer cells.
  • To elucidate the specific roles of IRS-1 and IRS-2 in IGF-IR-driven cancer cell behaviors.

Main Methods:

  • Utilized T47D-YA breast cancer cells, engineered to express IRS-1 or IRS-2 in the absence of endogenous IRS proteins.
  • Assessed the impact of IGF-I stimulation on cell proliferation and motility in cells with varying IRS expression.
  • Employed the IGF-IR inhibitor alphaIR-3 to confirm the dependence of observed phenotypes on IGF-IR signaling.

Main Results:

  • IGF-IR activation alone did not stimulate proliferation or motility in T47D-YA cells lacking IRS-1 and IRS-2.
  • Expression of IRS-1 led to IGF-I-stimulated proliferation but did not influence motility.
  • Expression of IRS-2 enhanced IGF-I-stimulated motility without affecting proliferation; alphaIR-3 inhibition was dependent on IRS expression.

Conclusions:

  • IGF-IR signaling requires IRS proteins to regulate breast cancer cell proliferation and motility.
  • IRS-1 and IRS-2 act as distinct mediators, with IRS-1 promoting proliferation and IRS-2 promoting motility.
  • IRS expression levels may serve as a predictive biomarker for responsiveness to IGF-IR targeted therapies.

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