title: Analysis of the adenomatous polyposis coli (APC) gene in childhood and adolescent germ cell tumors.
abstract: BACKGROUND
  Aberrant Wnt signaling due to deregulation of Wnt regulators is implicated in the development and progression of numerous embryonal tumors. This study addresses the questions if activation of Wnt signaling in germ cell tumors (GCTs) arising during childhood and adolescence is associated with aberrations of the tumor suppressor adenomatous polyposis coli (APC), and whether APC aberrations might be responsible for progression from benign teratoma to malignant yolk sac tumor (YST).
  
  
  METHODS
  Forty-eight GCTs were analyzed, including mature (n = 5) and immature (n = 7) teratomas, mixed malignant GCTs (n = 10), YSTs (n = 17) as well as dysgerminomas (n = 9). To screen APC for genetic aberrations, we conducted direct sequencing of the mutation cluster region (MCR), loss of heterozygosity analyses (LOH) and protein truncation test. Epigenetic analyses included methylation specific PCR and bisulfite genomic sequencing of the APC 1a promoter. Gene expression was determined by quantitative real-time PCR.
  
  
  RESULTS
  Aberrant promoter methylation was detected in YSTs, teratomas and mixed malignant GCTs, with a pronounced hypermethylation exclusively in YSTs (11/13) while dysgerminomas were not methylated (0/9). Teratomas (2/2) and YSTs (4/5) show LOH at the APC locus. However, neither mutations within the MCR nor truncated protein were detected. APC expression did not significantly vary between the different histological subgroups.
  
  
  CONCLUSIONS
  Methylation of APC and LOH 5q21-22 in YSTs and teratomas provide evidence for involvement of APC in the accumulation of β-catenin and activation of the WNT pathway. Our additional analyses suggest that APC is unlikely to be solely responsible for the formation and progression of childhood GCTs.
authors.affiliation: University of Düsseldorf, Medical faculty, Department of Pediatric Oncology, Hematology and Clinical Immunology, University Children's Hospital Düsseldorf, D-40225 Dusseldorf, Germany.
authors.forename: Vera
authors.initials: V
authors.lastname: Okpanyi
authors.forename: Dominik T
authors.initials: DT
authors.lastname: Schneider
authors.forename: Susanne
authors.initials: S
authors.lastname: Zahn
authors.forename: Sonja
authors.initials: S
authors.lastname: Sievers
authors.forename: Gabriele
authors.initials: G
authors.lastname: Calaminus
authors.forename: James C
authors.initials: JC
authors.lastname: Nicholson
authors.forename: Roger D
authors.initials: RD
authors.lastname: Palmer
authors.forename: Ivo
authors.initials: I
authors.lastname: Leuschner
authors.forename: Arndt
authors.initials: A
authors.lastname: Borkhardt
authors.forename: Stefan
authors.initials: S
authors.lastname: Schönberger
mesh_terms: D025601:Adenomatous Polyposis Coli Protein / Q000235:genetics*; D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D019175:DNA Methylation; D018240:Endodermal Sinus Tumor / Q000235:genetics* / Q000473:pathology; D057890:Epigenomics; D005260:Female; D017491:Genes, APC / Q000502:physiology; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D019656:Loss of Heterozygosity; D008297:Male; D018895:Microsatellite Repeats; D008875:Middle Aged; D009154:Mutation / Q000235:genetics*; D009373:Neoplasms, Germ Cell and Embryonal / Q000235:genetics* / Q000473:pathology; D020641:Polymorphism, Single Nucleotide / Q000235:genetics; D011379:Prognosis; D011401:Promoter Regions, Genetic / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D013724:Teratoma / Q000235:genetics* / Q000473:pathology
chemical_list: D025601:Adenomatous Polyposis Coli Protein; D012333:RNA, Messenger