Background. There is evidence that the stromal compartment may influence breast cancer responsiveness to chemotherapy. Our aim was to detect a stromal cell signature (using a direct approach of microdissected stromal cells) associated with response to neoadjuvant chemotherapy in locally advanced breast cancer, considering tumor down staging (to at least ypT1a/b,ypN0), as the best response. Patients and methods. Forty four patients diagnosed with locally advanced breast cancer (29 classified as estrogen receptor (ER) positive and 15, as ER negative) were included. Neoadjuvant chemotherapy consisted of doxorubicin/cyclophosphamide, followed by paclitaxel. Response was defined as downstaging to maximum ypT1a-b/ypN0. Stromal cells were microdissected from fresh frozen tumor samples and gene expression profile was determined using Agilent SurePrint G3 Human Gene Expression Microarrays. Expression levels were compared using MeV (MultiExperiment Viewer) software, applying SAM (Significance analysis of microarrays). Gene set enrichment analysis was used to identify gene sets correlated with the phenotype downstaging. Results: After chemotherapy, nine patients presented disease downstaging to maximum ypT1a-b/ypN0. Using SAM test (FDR 17), 11 sequences were differentially expressed, all of which (except for H2AFJ) more expressed in responsive tumors. Gene list enrichment analysis revealed three genes involved in abnormal cytotoxic T cell physiology: TOX, LY75 and SH2D1A. Gene sets correlated with tumor downstaging (FDR < 0.01), were mainly involved in immune response or lymphocyte activation, both in ER positive and ER negative samples. Conclusion: In locally advanced breast cancer, stromal cells may present specific features of immune response that may be associated with chemotherapy response.
Overall design
Stromal cells were microdissected from fresh frozen tumor samples and gene expression profile was determined using Agilent SurePrint G3 Human Gene Expression Microarrays. Expression levels were compared using MeV (MultiExperiment Viewer) software, applying SAM (Significance analysis of microarrays). Gene set enrichment analysis was used to identify gene sets correlated with the phenotype downstaging.
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