Epidermal growth factor receptor/HER2/insulin-like growth factor receptor signalling and oestrogen receptor activity in clinical breast cancer

Gee, Julia Margaret Wendy ORCID: https://orcid.org/0000-0001-6483-2015, Robertson, J. F., Gutteridge, E., Ellis, I. O., Pinder, S. E., Rubini, M. and Nicholson, Robert Ian 2005. Epidermal growth factor receptor/HER2/insulin-like growth factor receptor signalling and oestrogen receptor activity in clinical breast cancer. Endocrine-Related Cancer 12 (S1) , S99-S111. 10.1677/erc.1.01005

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Abstract

Breast cancer models of acquired tamoxifen resistance, oestrogen receptor (ER)+ /ER− de novo resistance and gene transfer studies cumulatively demonstrate the increased importance of growth factor receptor signalling, notably the epidermal growth factor receptor (EGFR)/HER2, in tamoxifen resistance. Our recent in vitro studies also suggest that EGFR signalling productively cross-talks with insulin-like growth factor receptor (IGF-1R) and, where present, activates ER on key AF-1 serine residues to facilitate acquired tamoxifen-resistant growth. This paper presents our immunohistochemical evidence that EGFR/HER2 signalling (i.e. transforming growth factor (TGF)α, EGFR and HER2 expression; phosphorylation of EGFR, HER2 and ERK1/2 MAP kinase) is also prominent in clinical de novo resistant and modestly increased in acquired tamoxifen-resistant states, suggesting that anti-EGFR/HER2 strategies may prove valuable treatments. Primary breast cancer samples employed were obtained for (1) patients subsequently treated with tamoxifen for advanced disease where endocrine response and survival data were available and (2) ER+ elderly patients during tamoxifen response and relapse. We also present our clinical immunohistochemical findings that IGF-1R expression, its phosphorylation on tyrosine 1316, and also phosphorylation on serine 118 of ER are not only prominent in ER+ tamoxifen-responsive disease, but are also detectable in ER+ de novo and acquired tamoxifen-resistant breast cancer, where there is evidence of EGFR/ER cross-talk. Our data suggest that agents to deplete effectively ER or IGF-1R signalling may be of value in treating ER+ de novo/acquired tamoxifen resistance in addition to tamoxifen-responsive disease in vivo. IGF-1R inhibitors may also prove valuable in ER− patients, since considerable IGF-1R signalling activity was apparent within ~50% of such tumours.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Pharmacy
Subjects:	R Medicine > RC Internal medicine > RC0254 Neoplasms. Tumors. Oncology (including Cancer) R Medicine > RM Therapeutics. Pharmacology
Additional Information:	This paper was presented at the 1st Tenovus/AstraZeneca Workshop, Cardiff (2005)
Publisher:	Society for Endocrinology
ISSN:	1351-0088
Last Modified:	18 Oct 2022 14:22
URI:	https://orca.cardiff.ac.uk/id/eprint/17226

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