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Systems Biology of Metabolic Regulation by Estrogen Receptor Signaling in Breast Cancer
10:36

Systems Biology of Metabolic Regulation by Estrogen Receptor Signaling in Breast Cancer

Published on: March 17, 2016

Epidermal growth factor receptor/HER2/insulin-like growth factor receptor signalling and oestrogen receptor activity

J M Gee1, J F Robertson, E Gutteridge

  • 1Tenovus Centre for Cancer Research, Welsh School of Pharmacy, Redwood Building, Cardiff University, Cardiff, UK. gee@cardiff.ac.uk

Endocrine-Related Cancer
|August 23, 2005
PubMed

Insights

Growth factor receptor signaling, particularly EGFR/HER2, is crucial in tamoxifen resistance. Targeting EGFR/HER2 and IGF-1R may offer new treatments for ER+ and ER- breast cancers.

Area of Science:

  • Oncology
  • Molecular Biology
  • Endocrinology

Background:

  • Tamoxifen resistance is a significant challenge in estrogen receptor-positive (ER+) breast cancer treatment.
  • Growth factor receptor signaling pathways, including epidermal growth factor receptor (EGFR)/HER2, play a critical role in tamoxifen resistance.
  • Cross-talk between EGFR and insulin-like growth factor receptor (IGF-1R) signaling, and with the estrogen receptor (ER), is implicated in tamoxifen-resistant growth.

Purpose of the Study:

  • To investigate the role of EGFR/HER2 and IGF-1R signaling in clinical samples of de novo and acquired tamoxifen-resistant breast cancer.
  • To evaluate the expression and phosphorylation status of key signaling molecules involved in tamoxifen resistance.
  • To assess the potential of targeting these pathways as therapeutic strategies for tamoxifen-resistant breast cancer.

Main Methods:

  • Immunohistochemistry was used to analyze primary breast cancer samples from patients with varying responses to tamoxifen.
  • Expression levels of transforming growth factor alpha (TGFα), EGFR, HER2, and IGF-1R were assessed.
  • Phosphorylation status of EGFR, HER2, ERK1/2 MAP kinase, and ER (at serine 118) and IGF-1R (at tyrosine 1316) were evaluated.

Main Results:

  • EGFR/HER2 signaling, including TGFα, EGFR, HER2, and ERK1/2 phosphorylation, was prominent in de novo resistant and increased in acquired tamoxifen-resistant breast cancers.
  • IGF-1R expression and phosphorylation, along with ER phosphorylation at serine 118, were detected in ER+ tamoxifen-responsive, de novo resistant, and acquired resistant tumors.
  • Significant IGF-1R signaling activity was observed in approximately 50% of ER- tumors.

Conclusions:

  • EGFR/HER2 signaling is a key feature of both de novo and acquired tamoxifen resistance, suggesting anti-EGFR/HER2 therapies could be beneficial.
  • IGF-1R signaling is active in tamoxifen-resistant ER+ breast cancer and may be a target for therapy, alongside ER or tamoxifen.
  • IGF-1R inhibitors may also represent a therapeutic option for ER- breast cancers, given the observed signaling activity.

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