Molecular profiling of inflammatory breast cancer:: Identification of a poor-prognosis gene expression signature

Purpose: Inflammatory breast cancer (IBC) is a rare but particularly aggressive form of primary breast cancer. The molecular mechanisms responsible for IBC are largely unknown. Experimental Design: To obtain further insight into the molecular pathogenesis of IBC, we used real-time quantitative reverse transcription (RT)-PCR to quantify the mRNA expression of 538 selected genes in IBC relative to non-IBC. Results: Twenty-seven (5.0%) of the 538 genes were significantly up-regulated in IBC compared with non-IBC. None were down-regulated. The 27 up-regulated genes mainly encoded transcription factors (JUN, EGR1, JUNB, FOS, FOSB, MYCN, and SNAIL1), growth factors (VEGF, DTR/HB-EGF, IGFBP7, IL6, ANGPT2, EREG, CCL3/MIP1A, and CCL5/RANTES) and growth factor receptors (TBXA2R, TNFRSF10A/TRAILR1, and ROBO2). We also identified a gene expression profile, based on MYCN, EREG, and SHH, which discriminated subgroups of IBC patients with good, intermediate, and poor outcome. Conclusion: Our study has identified a limited number of signaling pathways that require inappropriate activation for IBC development. Some of the up-regulated genes identified here could offer useful diagnostic or prognostic markers and could form the basis of novel therapeutic strategies.