Cell gene expression signatures in inflammatory breast cancer

Since publication of the landmark report by Al-hajj et al. provocatively suggesting that breast cancers may be organized in a cellular hierarchy similar to that described for hematogenous malignancies [1], numerous studies have sought to characterize the small, undifferentiated fraction of cells at the top of the hierarchy purported to give rise to all of the others. It is speculated that if these cells are in fact responsible for repopulating the tumor, the represent a critical target in cancer eradication. Many of the studies describing the phenotype of putative cancer stem cells suggest that they possess aggressive characteristics associated with treatment resistance, invasion, and metastases [2—5]. More recently, these cells have been described as most prevalent in tumors with poor prognostic features, including estrogen receptor (ER)’negative breast cancer, metaplastic breast cancer, and inflammatory breast cancer (IBC) [6—8]. Gene expression array analysis has become a valuable tool for grouping tumor types with similar features and prognosis and for elucidating the biology of specific subtypes. This chapter focuses on the progression of studies examining the gene expression profiles of IBC and the intersection of these efforts with similar work exploring the biology of cancer stem cells.