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Genome‐wide transcriptomic profiling of microdissected human breast tissue reveals differential expression of KIT (c‐Kit, CD117) and oestrogen receptor‐α (ERα) in response to therapeutic radiation
Author(s) -
Westbury Charlotte B,
ReisFilho Jorge S,
Dexter Tim,
MahlerAraujo Betania,
Fenwick Kerry,
Iravani Marjan,
Grigoriadis Anita,
Parry Suzanne,
Robertson David,
Mackay Alan,
Ashworth Alan,
Yarnold John R,
Isacke Clare M
Publication year - 2009
Publication title -
the journal of pathology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.964
H-Index - 184
eISSN - 1096-9896
pISSN - 0022-3417
DOI - 10.1002/path.2581
Subject(s) - stromal cell , biology , laser capture microdissection , pathology , cancer research , ctgf , breast cancer , connective tissue , gene expression profiling , receptor , gene expression , cancer , growth factor , medicine , gene , genetics
The pathogenesis of late normal tissue fibrosis after high‐dose ionizing radiation involves multiple cell types and signalling pathways but is not well understood. To identify the molecular changes occurring after radiotherapy, paired normal tissue samples were collected from the non‐irradiated breast and from the treated breast of women who had undergone curative radiotherapy for early breast cancer months or years previously. As radiation may induce distinct transcriptional changes in the different components of the breast, laser capture microdissection and gene expression microarray profiling were performed separately for epithelial and stromal components and selected genes were validated using immunohistochemistry. In the epithelial compartment, a reduction of KIT (c‐Kit; CD117) and a reciprocal increase in ESR1 (oestrogen receptor‐α, ERα) mRNA and protein levels were seen in irradiated compared to non‐irradiated samples. In the stromal compartment, extracellular matrix genes including FN1 (fibronectin 1) and CTGF (connective tissue growth factor; CCN2 ) were increased. Further investigation revealed that c‐Kit and ERα were expressed in distinct subpopulations of luminal epithelial cells. Interlobular c‐Kit‐positive mast cells were also increased in irradiated cases not showing features of post‐radiation atrophy. Pathway analysis revealed ‘cancer, reproductive system disease and tumour morphology’ as the most significantly enriched network in the epithelial compartment, whereas in the stromal component, a significant enrichment for ‘connective tissue disorders, dermatological diseases and conditions, genetic disorder’ and ‘cancer, tumour morphology, infection mechanism’ networks was observed. These data identify previously unreported changes in the epithelial compartment and show altered expression of genes implicated in late normal tissue injury in the stromal compartment of normal breast tissue. The findings are relevant to both fibrosis and atrophy occurring after radiotherapy for early breast cancer. Copyright © 2009 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.