title: Gene expression profiling identifies molecular subtypes of inflammatory breast cancer.
abstract: Breast cancer is a heterogeneous disease. Comprehensive gene expression profiles obtained using DNA microarrays have revealed previously indistinguishable subtypes of noninflammatory breast cancer (NIBC) related to different features of mammary epithelial biology and significantly associated with survival. Inflammatory breast cancer (IBC) is a rare, particular, and aggressive form of disease. Here we have investigated whether the five molecular subtypes described for NIBC (luminal A and B, basal, ERBB2 overexpressing, and normal breast-like) were also present in IBC. We monitored the RNA expression of approximately 8,000 genes in 83 breast tissue samples including 37 IBC, 44 NIBC, and 2 normal breast samples. Hierarchical clustering identified the five subtypes of breast cancer in both NIBC and IBC samples. These subtypes were highly similar to those defined in previous studies and associated with similar histoclinical features. The robustness of this classification was confirmed by the use of both alternative gene set and analysis method, and the results were corroborated at the protein level. Furthermore, we show that the differences in gene expression between NIBC and IBC and between IBC with and without pathologic complete response that we have recently reported persist in each subtype. Our results show that the expression signatures defining molecular subtypes of NIBC are also present in IBC. Obtained using different patient series and different microarray platforms, they reinforce confidence in the expression-based molecular taxonomy but also give evidence for its universality in breast cancer, independently of a specific clinical form.
authors.affiliation: Institut de Cancérologie de Marseille, Laboratoire d'Oncologie Moléculaire, Institut Paoli-Calmettes and UMR599 Institut National de la Santé et de la Recherche Médicale, IFR137, France.
authors.forename: François
authors.initials: F
authors.lastname: Bertucci
authors.forename: Pascal
authors.initials: P
authors.lastname: Finetti
authors.forename: Jacques
authors.initials: J
authors.lastname: Rougemont
authors.forename: Emmanuelle
authors.initials: E
authors.lastname: Charafe-Jauffret
authors.forename: Nathalie
authors.initials: N
authors.lastname: Cervera
authors.forename: Carole
authors.initials: C
authors.lastname: Tarpin
authors.forename: Catherine
authors.initials: C
authors.lastname: Nguyen
authors.forename: Luc
authors.initials: L
authors.lastname: Xerri
authors.forename: Rémi
authors.initials: R
authors.lastname: Houlgatte
authors.forename: Jocelyne
authors.initials: J
authors.lastname: Jacquemier
authors.forename: Patrice
authors.initials: P
authors.lastname: Viens
authors.forename: Daniel
authors.initials: D
authors.lastname: Birnbaum
mesh_terms: D000230:Adenocarcinoma / Q000145:classification* / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001943:Breast Neoplasms / Q000145:classification* / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D005260:Female; D020869:Gene Expression Profiling; D006801:Humans; D008875:Middle Aged; D016133:Polymerase Chain Reaction