Research article

EGFR associated expression profiles vary with breast tumor subtype

Katherine A Hoadley^1,2,3 , Victor J Weigman^2,3,4 , Cheng Fan^2,3 , Lynda R Sawyer⁵ , Xiaping He^2,3 , Melissa A Troester⁶ , Carolyn I Sartor^3,7 , Thais Rieger-House⁸ , Philip S Bernard⁸ , Lisa A Carey⁵ and Charles M Perou^1,2,3,9

¹Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA

²Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA

³Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA

⁴Department of Biology, Program of in Bioinformatics and Computational Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA

⁵Division of Hematology/Oncology, Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA

⁶Department of Public Health – Biostatistics and Epidemiology Concentration, University of Massachusetts Amherst, Amherst, MA, USA

⁷Department of Radiation Oncology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA

⁸Huntsman Cancer Institute and Department of Pathology, University of Utah School of Medicine, Salt Lake City, UT, USA

⁹Department of Pathology & Laboratory Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA

author email corresponding author email

BMC Genomics 2007, 8:258doi:10.1186/1471-2164-8-258

Published:	31 July 2007

Abstract

Background

The epidermal growth factor receptor (EGFR/HER1) and its downstream signaling events are important for regulating cell growth and behavior in many epithelial tumors types. In breast cancer, the role of EGFR is complex and appears to vary relative to important clinical features including estrogen receptor (ER) status. To investigate EGFR-signaling using a genomics approach, several breast basal-like and luminal epithelial cell lines were examined for sensitivity to EGFR inhibitors. An EGFR-associated gene expression signature was identified in the basal-like SUM102 cell line and was used to classify a diverse set of sporadic breast tumors.

Results

In vitro, breast basal-like cell lines were more sensitive to EGFR inhibitors compared to luminal cell lines. The basal-like tumor derived lines were also the most sensitive to carboplatin, which acted synergistically with cetuximab. An EGFR-associated signature was developed in vitro, evaluated on 241 primary breast tumors; three distinct clusters of genes were evident in vivo, two of which were predictive of poor patient outcomes. These EGFR-associated poor prognostic signatures were highly expressed in almost all basal-like tumors and many of the HER2+/ER- and Luminal B tumors.

Conclusion

These results suggest that breast basal-like cell lines are sensitive to EGFR inhibitors and carboplatin, and this combination may also be synergistic. In vivo, the EGFR-signatures were of prognostic value, were associated with tumor subtype, and were uniquely associated with the high expression of distinct EGFR-RAS-MEK pathway genes.