Gene expression signatures of morphologically normal breast tissue identify basal-like tumors.
BACKGROUND
The role of the cellular microenvironment in breast tumorigenesis has become an important research area. However, little is known about gene expression in histologically normal tissue adjacent to breast tumor, if this is influenced by the tumor, and how this compares with non-tumor-bearing breast tissue.


METHODS
To address this, we have generated gene expression profiles of morphologically normal epithelial and stromal tissue, isolated using laser capture microdissection, from patients with breast cancer or undergoing breast reduction mammoplasty (n = 44).


RESULTS
Based on this data, we determined that morphologically normal epithelium and stroma exhibited distinct expression profiles, but molecular signatures that distinguished breast reduction tissue from tumor-adjacent normal tissue were absent. Stroma isolated from morphologically normal ducts adjacent to tumor tissue contained two distinct expression profiles that correlated with stromal cellularity, and shared similarities with soft tissue tumors with favorable outcome. Adjacent normal epithelium and stroma from breast cancer patients showed no significant association between expression profiles and standard clinical characteristics, but did cluster ER/PR/HER2-negative breast cancers with basal-like subtype expression profiles with poor prognosis.


CONCLUSIONS
Our data reveal that morphologically normal tissue adjacent to breast carcinomas has not undergone significant gene expression changes when compared to breast reduction tissue, and provide an important gene expression dataset for comparative studies of tumor expression profiles.
Finak
Greg
G
Molecular Oncology Group, McGill University Health Centre, 687 Pine Ave, West, H3A 1A1, Quebec, Canada.
Sadekova
Svetlana
S
Pepin
Francois
F
Hallett
Michael
M
Meterissian
Sarkis
S
Halwani
Fawaz
F
Khetani
Karim
K
Souleimanova
Margarita
M
Zabolotny
Brent
B
Omeroglu
Atilla
A
Park
Morag
M
D000328:Adult; D001940:Breast / Q000502:physiology*; D001943:Breast Neoplasms / Q000235:genetics*; D018270:Carcinoma, Ductal, Breast / Q000235:genetics*; D004847:Epithelial Cells; D005260:Female; D020869:Gene Expression Profiling; D006801:Humans; D042282:Microdissection; D008875:Middle Aged; D017154:Stromal Cells