System-Wide Analysis Reveals a Complex Network of Tumor-Fibroblast Interactions Involved in Tumorigenicity

Weve undertaken a genome-wide approach to identify and test genes in fibroblasts that are both induced upon interaction with basal breast cancer cells in culture and upregulated in stromal cells from primary human breast cancers. Several of the upregulated genes encode secreted growth factors or cytokines. Using RNAi and a co-injection tumorigenicity assay, we determined that the majority of secreted factors selected for functional validation played significant, yet functionally diverse, roles in promoting tumorigenicity. Rather than a single major mediator, these results indicate multiple points of intervention to prevent fibroblasts from supporting basal breast cancer. Additionally, we show that breast cancer subtypes differ markedly in the expression of these and other stromally secreted proteins using data from microdissected stromal samples.

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Rajaram M, Li J, Egeblad M, Powers RS