title: Intragenic anaplastic lymphoma kinase (ALK) rearrangements: translocations as a novel mechanism of ALK activation in neuroblastoma tumors.
abstract: Anaplastic lymphoma kinase (ALK) has been demonstrated to be deregulated in sporadic as well as in familiar cases of neuroblastoma (NB). Whereas ALK-fusion proteins are common in lymphoma and lung cancer, there are few reports of ALK rearrangements in NB indicating that ALK mainly exerts its oncogenic capacity via activating mutations and/or overexpression in this tumor type. In this study, 332 NB tumors and 13 cell lines were screened by high resolution single nucleotide polymorphism microarray. Gain of 2p was detected in 23% (60/332) of primary tumors and 46% (6/13) of cell lines, while breakpoints at the ALK locus were detected in four primary tumors and two cell lines. These were further analyzed by next generation sequencing and a targeted enrichment approach. Samples with both ALK and MYCN amplification displayed complex genomic rearrangements with multiple breakpoints within the amplicon. None of the translocations characterized in primary NB tumors are likely to result in a chimeric protein. However, immunohistochemical analysis reveals high levels of phosphorylated ALK in these samples despite lack of initial exons, possibly due to alternative transcription initiation sites. Both ALK proteins predicted to arise from such alterations and from the abnormal ALK exon 4-11 deletion observed in the CLB-BAR cell line show strong activation of downstream targets STAT3 and extracellular signal-regulated kinase (ERK) when expressed in PC12 cells. Taken together, our data indicate a novel, although rare, mechanism of ALK activation with implications for NB tumorigenesis.
authors.affiliation: Department of Medical and Clinical Genetics, Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden.
authors.forename: Susanne
authors.initials: S
authors.lastname: Fransson
authors.forename: Magnus
authors.initials: M
authors.lastname: Hansson
authors.forename: Kristina
authors.initials: K
authors.lastname: Ruuth
authors.forename: Anna
authors.initials: A
authors.lastname: Djos
authors.forename: Ana
authors.initials: A
authors.lastname: Berbegall
authors.forename: Niloufar
authors.initials: N
authors.lastname: Javanmardi
authors.forename: Jonas
authors.initials: J
authors.lastname: Abrahamsson
authors.forename: Ruth H
authors.initials: RH
authors.lastname: Palmer
authors.forename: Rosa
authors.initials: R
authors.lastname: Noguera
authors.forename: Bengt
authors.initials: B
authors.lastname: Hallberg
authors.forename: Per
authors.initials: P
authors.lastname: Kogner
authors.forename: Tommy
authors.initials: T
authors.lastname: Martinsson
mesh_terms: D000077548:Anaplastic Lymphoma Kinase; D000818:Animals; D045744:Cell Line, Tumor; D056905:Chromosome Breakpoints; D005091:Exons; D048049:Extracellular Signal-Regulated MAP Kinases / Q000235:genetics / Q000378:metabolism; D015972:Gene Expression Regulation, Neoplastic; D015321:Gene Rearrangement; D006801:Humans; D009447:Neuroblastoma / Q000235:genetics* / Q000378:metabolism; D016716:PC12 Cells; D020641:Polymorphism, Single Nucleotide; D051381:Rats; D020794:Receptor Protein-Tyrosine Kinases / Q000235:genetics* / Q000378:metabolism; D050796:STAT3 Transcription Factor / Q000235:genetics / Q000378:metabolism; D014178:Translocation, Genetic
chemical_list: D050796:STAT3 Transcription Factor; C000626173:ALK protein, human; C000626175:Alk protein, rat; D000077548:Anaplastic Lymphoma Kinase; D020794:Receptor Protein-Tyrosine Kinases; D048049:Extracellular Signal-Regulated MAP Kinases