Abstract 3393: Identification of genes mediating early dissemination of tumor cells in breast cancer

The presence of disseminated tumor cells in bone marrow (BM) at primary breast cancer diagnosis is an independent prognostic factor. We have recently shown that there is a specific gene expression signature associated with BM micrometastasis in lung cancer patients (Wrage et al., CCR 2009). Our aim was therefore, to assess whether early metastatic spread of breast tumor cells into BM is also associated with a specific genetic signature. The gene expression profiles of primary early stage breast cancer patients (T1-2, N0, M0) with (n=15) and without (n=15) early tumor cell dissemination into BM were analyzed using the Affymetrix GeneChip platform. The BM status was assessed by immunostaining the BM samples with anti-cytokeratin antibody A45-B/B3. Gene expression data were normalized using gcrma and customized chip description files were used to re-map all probes to ENSEMBL transcripts. Rank sum test analysis was used to obtain transcripts that were significantly differentially expressed between BM positive and BM negative patients. Five publicly available breast cancer and three lung cancer expression data sets were used to correlate the findings with survival information. When using false discovery rate of 0.2 and a p-value