Gene expression profiling of the tumor microenvironment during breast cancer progression

Breast Cancer Res. 2009;11(1):R7. doi: 10.1186/bcr2222. Epub 2009 Feb 2.


Introduction: The importance of the tumor microenvironment in breast cancer has been increasingly recognized. Critical molecular changes in the tumor stroma accompanying cancer progression, however, remain largely unknown. We conducted a comparative analysis of global gene expression changes in the stromal and epithelial compartments during breast cancer progression from normal to preinvasive to invasive ductal carcinoma.

Methods: We combined laser capture microdissection and gene expression microarrays to analyze 14 patient-matched normal epithelium, normal stroma, tumor epithelium and tumor-associated stroma specimens. Differential gene expression and gene ontology analyses were performed.

Results: Tumor-associated stroma undergoes extensive gene expression changes during cancer progression, to a similar extent as that seen in the malignant epithelium. Highly upregulated genes in the tumor-associated stroma include constituents of the extracellular matrix and matrix metalloproteases, and cell-cycle-related genes. Decreased expression of cytoplasmic ribosomal proteins and increased expression of mitochondrial ribosomal proteins were observed in both the tumor epithelium and the stroma. The transition from preinvasive to invasive growth was accompanied by increased expression of several matrix metalloproteases (MMP2, MMP11 and MMP14). Furthermore, as observed in malignant epithelium, a gene expression signature of histological tumor grade also exists in the stroma, with high-grade tumors associated with increased expression of genes involved in immune response.

Conclusions: Our results suggest that the tumor microenvironment participates in tumorigenesis even before tumor cells invade into stroma, and that it may play important roles in the transition from preinvasive to invasive growth. The immune cells in the tumor stroma may be exploited by the malignant epithelial cells in high-grade tumors for aggressive invasive growth.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Adult
  • Breast Neoplasms / genetics*
  • Breast Neoplasms / metabolism
  • Breast Neoplasms / pathology
  • Carcinoma, Ductal, Breast / genetics
  • Carcinoma, Ductal, Breast / metabolism
  • Carcinoma, Ductal, Breast / pathology
  • Carcinoma, Intraductal, Noninfiltrating / genetics
  • Carcinoma, Intraductal, Noninfiltrating / metabolism
  • Carcinoma, Intraductal, Noninfiltrating / pathology
  • Disease Progression
  • Epithelial Cells / metabolism*
  • Epithelial Cells / pathology
  • Extracellular Matrix / metabolism
  • Extracellular Matrix / pathology
  • Female
  • Gene Expression Profiling*
  • Gene Expression Regulation, Neoplastic / physiology*
  • Humans
  • Immunoenzyme Techniques
  • Lasers
  • Microdissection
  • Middle Aged
  • Neoplasm Invasiveness
  • Oligonucleotide Array Sequence Analysis
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • Reverse Transcriptase Polymerase Chain Reaction
  • Stromal Cells / metabolism*
  • Stromal Cells / pathology


  • RNA, Messenger