title: Sporadic and Thorotrast-induced angiosarcomas of the liver manifest frequent and multiple point mutations in K-ras-2.
abstract: Hepatic angiosarcoma (HA) is an uncommon neoplasm associated with known etiologic factors in 25% to 42% of cases. It is, however, one of the most common sarcomas found in the liver. The aim of this study was to find was to find mutations in the K-ras-2 oncogene in sporadic and Thorotrast (TT)-induced HA. Point mutations in K-ras-2 were sought in archival, formalin-fixed tissue blocks from 24 patients with angiosarcoma. Of these, 19 cases were sporadic and 5 were TT-induced. Mutational analysis was performed by topographic microdissection with PCR amplification followed by genotyping. Specific mutations were determined by two independent methods: (a) direct sequencing of the PCR product confirmed by rePCR and by using a different sequencing primer, and (b) PCR-based selective enrichment of mutant DNA by endonuclease digestion followed by heteroduplex DNA analysis using denaturing gradient gel electrophoresis. Eleven K-ras-2 point mutations were detected in 7 of 24 (29%) tumors, including 5 of 19 (26%) sporadic HA and 2 of 5 (40%) TT-induced HA. There were seven G:C > A:T and four G:C > T:A mutations. All seven mutated tumors contained a codon 12-aspartate amino acid substitution. In addition, a second codon 12-cysteine mutant cell population was present in one of two codon 12-aspartate mutated TT-induced HA and in three of five codon 12-aspartate sporadic tumors. Of these four tumors, three contained both aspartate and cysteine mutations and were composed of multiple nodules; the fourth was a single mass. Seventeen tumors had multiple nodules; whereas 5 had a K-ras-2 mutation, 12 were wild-type. The molecular pathology of both sporadic and TT-induced HA is characterized by a high rate of K-ras-2 mutations characteristic of oxidative damage (ie, G:C > A:T and G:C > T:A mutations) resulting in two mutated population sets: codon 12 GGT > GAT and GGT > TGT (glycine to aspartic acid and cysteine). This is, to date, the first study to characterize the K-ras-2 gene mutations within human sporadic and TT-induced HA by direct sequence analysis and denaturing gradient gel electrophoresis. These data further support the hypothesis linking adduct-forming vinyl chloride exposure to HA containing a much higher frequency of K-ras-2 mutations and a mutational spectrum characteristic of chloroethylene oxide, a carcinogenic metabolite of vinyl chloride.
authors.affiliation: Laboratory of Human Carcinogenesis, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA.
authors.forename: R M
authors.initials: RM
authors.lastname: Przygodzki
authors.forename: S D
authors.initials: SD
authors.lastname: Finkelstein
authors.forename: P
authors.initials: P
authors.lastname: Keohavong
authors.forename: D
authors.initials: D
authors.lastname: Zhu
authors.forename: A
authors.initials: A
authors.lastname: Bakker
authors.forename: P A
authors.initials: PA
authors.lastname: Swalsky
authors.forename: Y
authors.initials: Y
authors.lastname: Soini
authors.forename: K G
authors.initials: KG
authors.lastname: Ishak
authors.forename: W P
authors.initials: WP
authors.lastname: Bennett
mesh_terms: D000328:Adult; D000368:Aged; D002273:Carcinogens; D005260:Female; D011905:Genes, ras; D006394:Hemangiosarcoma / Q000209:etiology / Q000235:genetics* / Q000473:pathology; D006801:Humans; D008113:Liver Neoplasms / Q000209:etiology / Q000235:genetics* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D009381:Neoplasms, Radiation-Induced / Q000209:etiology / Q000235:genetics*; D016273:Occupational Exposure; D017354:Point Mutation; D016133:Polymerase Chain Reaction; D013911:Thorium Dioxide
chemical_list: D002273:Carcinogens; D013911:Thorium Dioxide