title: Lack of microsatellite instability in neoplasms of ampulla of Vater.
abstract: To clarify the genetic background of ampullary neoplasm, we investigated the occurrence of microsatellite instability (MSI) in 64 samples of neoplasm of the ampulla of Vater. Eight out of 22 adenomas (34.6%), nine out of 32 carcinomas (28.1%) and one metastatic lesion (10.0%) showed MSI in 1-3 of the nine dinucleotide markers; those cases are categorized into microsatellite instability-low (MSI-L). The remaining samples were stable with respect to all of the tested markers. None of the samples showed a frameshift mutation in the poly A-tract of BAT-26 or transforming growth factor-beta type II receptor, which are frequently mutated in gastric or colorectal cancers showing microsatellite instability. To confirm our finding, we stained 93 ampullary neoplasms with antibodies against the mismatch repair proteins: hMLH1 and hMSH2. All tumors were found to express mismatch repair proteins. In contrast to gastric or colorectal cancers, MSI does not play an important role in the carcinogenesis of ampullary carcinoma.
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000230:Adenocarcinoma / Q000235:genetics* / Q000378:metabolism / Q000556:secondary; D000236:Adenoma / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D014670:Ampulla of Vater / Q000378:metabolism / Q000473:pathology*; D020137:Base Pair Mismatch / Q000235:genetics; D014408:Biomarkers, Tumor / Q000378:metabolism; D002352:Carrier Proteins; D003138:Common Bile Duct Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D004268:DNA-Binding Proteins / Q000378:metabolism; D018900:Dinucleotide Repeats / Q000235:genetics*; D006801:Humans; D007124:Immunoenzyme Techniques; D000070957:MutL Protein Homolog 1; D051718:MutS Homolog 2 Protein; D009363:Neoplasm Proteins / Q000378:metabolism; D009378:Neoplasms, Multiple Primary; D009687:Nuclear Proteins; D011518:Proto-Oncogene Proteins / Q000378:metabolism
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D014408:Biomarkers, Tumor; D002352:Carrier Proteins; D004268:DNA-Binding Proteins; C501486:MLH1 protein, human; D009363:Neoplasm Proteins; D009687:Nuclear Proteins; D011518:Proto-Oncogene Proteins; C497172:MSH2 protein, human; D000070957:MutL Protein Homolog 1; D051718:MutS Homolog 2 Protein