title: ERBB3 is a marker of a ganglioneuroblastoma/ganglioneuroma-like expression profile in neuroblastic tumours.
abstract: BACKGROUND
  Neuroblastoma (NB) tumours are commonly divided into three cytogenetic subgroups. However, by unsupervised principal components analysis of gene expression profiles we recently identified four distinct subgroups, r1-r4. In the current study we characterized these different subgroups in more detail, with a specific focus on the fourth divergent tumour subgroup (r4).
  
  
  METHODS
  Expression microarray data from four international studies corresponding to 148 neuroblastic tumour cases were subject to division into four expression subgroups using a previously described 6-gene signature. Differentially expressed genes between groups were identified using Significance Analysis of Microarray (SAM). Next, gene expression network modelling was performed to map signalling pathways and cellular processes representing each subgroup. Findings were validated at the protein level by immunohistochemistry and immunoblot analyses.
  
  
  RESULTS
  We identified several significantly up-regulated genes in the r4 subgroup of which the tyrosine kinase receptor ERBB3 was most prominent (fold change: 132-240). By gene set enrichment analysis (GSEA) the constructed gene network of ERBB3 (n = 38 network partners) was significantly enriched in the r4 subgroup in all four independent data sets. ERBB3 was also positively correlated to the ErbB family members EGFR and ERBB2 in all data sets, and a concurrent overexpression was seen in the r4 subgroup. Further studies of histopathology categories using a fifth data set of 110 neuroblastic tumours, showed a striking similarity between the expression profile of r4 to ganglioneuroblastoma (GNB) and ganglioneuroma (GN) tumours. In contrast, the NB histopathological subtype was dominated by mitotic regulating genes, characterizing unfavourable NB subgroups in particular. The high ErbB3 expression in GN tumour types was verified at the protein level, and showed mainly expression in the mature ganglion cells.
  
  
  CONCLUSIONS
  Conclusively, this study demonstrates the importance of performing unsupervised clustering and subtype discovery of data sets prior to analyses to avoid a mixture of tumour subtypes, which may otherwise give distorted results and lead to incorrect conclusions. The current study identifies ERBB3 as a clear-cut marker of a GNB/GN-like expression profile, and we suggest a 7-gene expression signature (including ERBB3) as a complement to histopathology analysis of neuroblastic tumours. Further studies of ErbB3 and other ErbB family members and their role in neuroblastic differentiation and pathogenesis are warranted.
authors.affiliation: Department of Clinical Genetics, Institution of Biomedicine, Box 413, S- 405 30, Gothenburg University, Gothenburg, Sweden. frida.abel@gu.se.
authors.forename: Annica
authors.initials: A
authors.lastname: Wilzén
authors.forename: Cecilia
authors.initials: C
authors.lastname: Krona
authors.forename: Baldur
authors.initials: B
authors.lastname: Sveinbjörnsson
authors.forename: Erik
authors.initials: E
authors.lastname: Kristiansson
authors.forename: Daniel
authors.initials: D
authors.lastname: Dalevi
authors.forename: Ingrid
authors.initials: I
authors.lastname: Øra
authors.forename: Katleen
authors.initials: K
authors.lastname: De Preter
authors.forename: Raymond L
authors.initials: RL
authors.lastname: Stallings
authors.forename: John
authors.initials: J
authors.lastname: Maris
authors.forename: Rogier
authors.initials: R
authors.lastname: Versteeg
authors.forename: Staffan
authors.initials: S
authors.lastname: Nilsson
authors.forename: Per
authors.initials: P
authors.lastname: Kogner
authors.forename: Frida
authors.initials: F
authors.lastname: Abel
mesh_terms: D014408:Biomarkers, Tumor / Q000235:genetics / Q000378:metabolism*; D018305:Ganglioneuroblastoma / Q000378:metabolism*; D005729:Ganglioneuroma / Q000378:metabolism*; D015972:Gene Expression Regulation, Neoplastic; D063990:Gene Ontology; D053263:Gene Regulatory Networks; D006801:Humans; D020411:Oligonucleotide Array Sequence Analysis; D010524:Peripheral Nervous System Neoplasms / Q000378:metabolism*; D020893:Receptor, ErbB-3 / Q000235:genetics / Q000378:metabolism*; D059467:Transcriptome; D015854:Up-Regulation
chemical_list: D014408:Biomarkers, Tumor; C581292:ERBB3 protein, human; D020893:Receptor, ErbB-3