Lymph node metastases display gene expression profiles of their primary breast carcinomas
© BioMed Central 2005
Published: 17 June 2005
The axillary lymph node status is the most powerful prognostic factor for breast cancer patients to date. The molecular mechanisms that control lymph node metastasis, however, remain poorly understood. The aim of our study was to define patterns of genes or gene regulatory pathways that drive breast cancer lymph node metastasis.
We compared the gene expression profiles of 15 primary breast carcinomas and their matching lymph node metastases using microarrays. Furthermore, we analyzed the expression profiles of two primary breast tumors and a metastasis obtained from the same patient.
The gene expression profile of a primary breast carcinoma is more similar to its affiliated metastasis than the second primary tumor of the same patient. In general, primary breast carcinomas and lymph node metastases do not differ at the transcriptional level by a common subset of genes. However, subtle differences in the expression of genes involved in extracellular matrix organization and growth factor signaling are detected in individual pairs of matching primary and metastatic tumors. Surprisingly, however, different sets of these genes are either upregulated or downregulated in lymph node metastases.
The overall gene expression profiles of primary breast carcinomas are maintained in their lymph node metastases. This similarity in gene expression can be attributed to tumor-intrinsic factors rather than to patient-specific factors. No common denominator for breast cancer lymph node metastasis could be identified, suggesting that breast carcinomas do not use a shared gene set to accomplish lymph node metastasis.