title: Pathogenesis of adenocarcinoma in Peutz-Jeghers syndrome.
abstract: Peutz-Jeghers syndrome (PJS) is an autosomal dominant condition characterized by intestinal hamartomatous polyps, mucocutaneous melanin deposition, and increased risk of cancer. Families with PJS from the Johns Hopkins Polyposis Registry were studied to identify the molecular basis of this syndrome and to characterize the pathogenesis of gastrointestinal hamartomas and adenocarcinomas in PJS patients. Linkage analysis in the family originally described by Jeghers in 1949 and five other families confirmed linkage to 19p13.3 near a recently identified gene responsible for PJS. Germ-line mutations in this gene, STK11, were identified in all six families by sequencing genomic DNA. Analysis of hamartomas and adenocarcinomas from patients with PJS identified loss of heterozygosity (LOH) of 19p markers near STK11 in 70% of tumors. Haplotype analysis indicated that the retained allele carried a germ-line mutation, confirming that STK11 is a tumor suppressor gene. LOH of 17p and 18q was identified in an adenocarcinoma but not in hamartomas, implying that allelic loss of these two regions corresponds to late molecular events in the pathogenesis of cancer in PJS. The adenocarcinomas showing 17p LOH also demonstrated altered p53 by immunohistochemistry. None of the 18 PJS tumors showed microsatellite instability, LOH on 5q near APC, or mutations in codons 12 or 13 of the K-ras proto-oncogene. These data provide evidence that STK11 is a tumor suppressor gene that acts as an early gatekeeper regulating the development of hamartomas in PJS and suggest that hamartomas may be pathogenetic precursors of adenocarcinoma. Additional somatic mutational events underlie the progression of hamartomas to adenocarcinomas, and some of these somatic mutations are common to the later stages of tumor progression seen in the majority of colorectal carcinomas.
authors.affiliation: Division of Molecular Medicine and Genetics, University of Michigan, Ann Arbor 48109, USA. sgruber@umich.edu
authors.forename: S B
authors.initials: SB
authors.lastname: Gruber
authors.forename: M M
authors.initials: MM
authors.lastname: Entius
authors.forename: G M
authors.initials: GM
authors.lastname: Petersen
authors.forename: S J
authors.initials: SJ
authors.lastname: Laken
authors.forename: P A
authors.initials: PA
authors.lastname: Longo
authors.forename: R
authors.initials: R
authors.lastname: Boyer
authors.forename: A M
authors.initials: AM
authors.lastname: Levin
authors.forename: U J
authors.initials: UJ
authors.lastname: Mujumdar
authors.forename: J M
authors.initials: JM
authors.lastname: Trent
authors.forename: K W
authors.initials: KW
authors.lastname: Kinzler
authors.forename: B
authors.initials: B
authors.lastname: Vogelstein
authors.forename: S R
authors.initials: SR
authors.lastname: Hamilton
authors.forename: M H
authors.initials: MH
authors.lastname: Polymeropoulos
authors.forename: G J
authors.initials: GJ
authors.lastname: Offerhaus
authors.forename: F M
authors.initials: FM
authors.lastname: Giardiello
mesh_terms: D000230:Adenocarcinoma / Q000209:etiology* / Q000235:genetics*; D002888:Chromosomes, Human, Pair 19; D004252:DNA Mutational Analysis; D005260:Female; D005767:Gastrointestinal Diseases / Q000209:etiology / Q000235:genetics; D005770:Gastrointestinal Neoplasms / Q000209:etiology* / Q000235:genetics*; D008040:Genetic Linkage; D018095:Germ-Line Mutation; D006222:Hamartoma / Q000209:etiology / Q000235:genetics; D006239:Haplotypes; D006801:Humans; D019656:Loss of Heterozygosity; D008297:Male; D010375:Pedigree; D010580:Peutz-Jeghers Syndrome / Q000150:complications* / Q000235:genetics*; D010641:Phenotype; D000090063:Proto-Oncogene Mas