title: Endometrial and colorectal tumors from patients with hereditary nonpolyposis colon cancer display different patterns of microsatellite instability.
abstract: The colorectum and uterine endometrium are the two most commonly affected organs in hereditary nonpolyposis colon cancer (HNPCC), but the genetic basis of organ selection is poorly understood. As tumorigenesis in HNPCC is driven by deficient DNA mismatch repair (MMR), we compared its typical consequence, instability at microsatellite sequences, in colorectal and endometrial cancers from patients with identical predisposing mutations in the MMR genes MLH1 or MSH2. Analysis of non-coding (BAT25, BAT26, and BAT40) and coding mononucleotide repeats (MSH6, MSH3, MLH3, BAX, IGF2R, TGF beta RII, and PTEN), as well as MLH1- and MSH2-linked dinucleotide repeats (D3S1611 and CA7) revealed significant differences, both quantitative and qualitative, between the two tumor types. Whereas colorectal cancers displayed a predominant pattern consisting of instability at the BAT loci (in 89% of tumors), TGF beta RII (73%), dinucleotide repeats (70%), MSH3 (43%), and BAX (30%), no such single pattern was discernible in endometrial cancers. Instead, the pattern was more heterogeneous and involved a lower proportion of unstable markers per tumor (mean 0.27 for endometrial cancers versus 0.45 for colorectal cancers, P < 0.001) and shorter allelic shifts for BAT markers (average 5.1 bp for unstable endometrial cancers versus 9.3 bp for colorectal cancers, P < 0.001). Among the individual putative "target" loci, PTEN instability was associated with endometrial cancers and TGF beta RII instability with colon cancers. The different instability profiles in endometrial and colorectal cancers despite identical genetic predisposition underlines organ-specific differences that may be important determinants of the HNPCC tumor spectrum.
authors.affiliation: Department of Medical Genetics, University of Helsinki, Helsinki, Finland.
authors.forename: Shannon A
authors.initials: SA
authors.lastname: Kuismanen
authors.forename: Anu-Liisa
authors.initials: AL
authors.lastname: Moisio
authors.forename: Pascal
authors.initials: P
authors.lastname: Schweizer
authors.forename: Kaspar
authors.initials: K
authors.lastname: Truninger
authors.forename: Reijo
authors.initials: R
authors.lastname: Salovaara
authors.forename: Johanna
authors.initials: J
authors.lastname: Arola
authors.forename: Ralf
authors.initials: R
authors.lastname: Butzow
authors.forename: Josef
authors.initials: J
authors.lastname: Jiricny
authors.forename: Minna
authors.initials: M
authors.lastname: Nyström-Lahti
authors.forename: Päivi
authors.initials: P
authors.lastname: Peltomäki
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000483:Alleles; D002352:Carrier Proteins; D015179:Colorectal Neoplasms / Q000235:genetics*; D003123:Colorectal Neoplasms, Hereditary Nonpolyposis / Q000150:complications* / Q000235:genetics*; D004268:DNA-Binding Proteins; D018900:Dinucleotide Repeats / Q000235:genetics; D016889:Endometrial Neoplasms / Q000235:genetics*; D005260:Female; D018095:Germ-Line Mutation; D006801:Humans; D018895:Microsatellite Repeats; D000070957:MutL Protein Homolog 1; D051718:MutS Homolog 2 Protein; D009363:Neoplasm Proteins / Q000235:genetics; D009687:Nuclear Proteins; D051059:PTEN Phosphohydrolase; D010744:Phosphoric Monoester Hydrolases / Q000235:genetics; D011518:Proto-Oncogene Proteins / Q000235:genetics; D019680:Trinucleotide Repeat Expansion; D025521:Tumor Suppressor Proteins / Q000235:genetics
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; D004268:DNA-Binding Proteins; C501486:MLH1 protein, human; D009363:Neoplasm Proteins; D009687:Nuclear Proteins; D011518:Proto-Oncogene Proteins; D025521:Tumor Suppressor Proteins; D010744:Phosphoric Monoester Hydrolases; D051059:PTEN Phosphohydrolase; C494929:PTEN protein, human; C497172:MSH2 protein, human; D000070957:MutL Protein Homolog 1; D051718:MutS Homolog 2 Protein