title: Distinct molecular phenotype of inflammatory breast cancer compared to non-inflammatory breast cancer using Affymetrix-based genome-wide gene-expression analysis.
abstract: The present study aims at a platform-independent confirmation of previously obtained cDNA microarray results on inflammatory breast cancer (IBC) using Affymetrix chips. Gene-expression data of 19 IBC and 40 non-IBC specimens were subjected to clustering and principal component analysis. The performance of a previously identified IBC signature was tested using clustering and gene set enrichment analysis. The presence of different cell-of-origin subtypes in IBC was investigated and confirmed using immunohistochemistry on a TMA. Differential gene expression was analysed using SAM and topGO was used to identify the fingerprints of a pro-metastatic-signalling pathway. IBC and non-IBC have distinct gene-expression profiles. The differences in gene expression between IBC and non-IBC are captured within an IBC signature, identified in a platform-independent manner. Part of the gene-expression differences between IBC and non-IBC are attributable to the differential presence of the cell-of-origin subtypes, since IBC primarily segregated into the basal-like or ErbB2-overexpressing group. Strikingly, IBC tumour samples more closely resemble the gene-expression profile of T1/T2 tumours than the gene-expression profile or T3/T4 tumours. We identified the insulin-like growth factor-signalling pathway, potentially contributing to the biology of IBC. Our previous results have been validated in a platform-independent manner. The distinct biological behaviour of IBC is reflected in a distinct gene-expression profile. The fact that IBC tumours are quickly arising tumours might explain the close resemblance of the IBC gene-expression profile to the expression profile of T1/T2 tumours.
authors.affiliation: Translational Cancer Research Group (Lab Pathology), University of Antwerp, Universiteitsplein 1, Wilrijk B2610, Belgium.
authors.forename: S
authors.initials: S
authors.lastname: Van Laere
authors.forename: I
authors.initials: I
authors.lastname: Van der Auwera
authors.forename: G
authors.initials: G
authors.lastname: Van den Eynden
authors.forename: P
authors.initials: P
authors.lastname: Van Hummelen
authors.forename: P
authors.initials: P
authors.lastname: van Dam
authors.forename: E
authors.initials: E
authors.lastname: Van Marck
authors.forename: P B
authors.initials: PB
authors.lastname: Vermeulen
authors.forename: L
authors.initials: L
authors.lastname: Dirix
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001943:Breast Neoplasms / Q000235:genetics* / Q000473:pathology*; D016000:Cluster Analysis; D005260:Female; D015870:Gene Expression; D020869:Gene Expression Profiling; D006801:Humans; D007150:Immunohistochemistry; D008875:Middle Aged; D010641:Phenotype; D025341:Principal Component Analysis; D046888:Tissue Array Analysis