title: Microsatellite instability at a tetranucleotide repeat in type I endometrial carcinoma.
abstract: BACKGROUND
  Microsatellite instability (MSI) at tri- or tetranucleotide repeat markers (elevated microsatellite alterations at selected tetranucleotide repeat, EMAST) has been recently described. But, the underlying genetic mechanism of EMAST is unclear. This study was to investigate the prevalence of EMAST, in type I endometrial carcinoma, and to determine the correlation between the MSI status and mismatch repair genes (MMR) or p53.
  
  
  METHODS
  We examined the 3 mono-, 3 di-, and 6 tetranucleotide repeat markers by PCR in 39 cases of type I endometrial carcinoma and performed the immunohistochemistry of hMSH2, hMLH1, and p53 protein.
  
  
  RESULTS
  More than two MSI at mono- and dinucleotide repeat markers was noted in 8 cases (MSI-H, 20.5%). MSI, at a tetranucleotide repeat, was detected in 15 cases (EMAST, 38.5%). In remaining 16 cases, any MSI was not observed. (MSS, 42.1%), MSI status was not associated with FIGO stage, grade or depth of invasion. The absence of expression of either one of both hMSH2 or hMLH1 was noted in seven (87.5%) of eight MSI-H tumors, one (6.3%) of 16 MSS tumors, and five (33.3%) of 15 EMAST tumors. (p = 0.010) The expression of p53 protein was found in one (12.5%) of eight MSI-H tumors, five (31.3%) of 16 MSS tumors, and seven of 15 EMAST tumors. (p = 0.247)
  
  
  CONCLUSIONS
  Our results showed that about 38.5% of type I endometrial carcinomas exhibited EMAST, and that EMAST was rarely associated with alteration of hMSH2 or hMLH1.
authors.affiliation: Department of Pathology, Chonnam National University Medical School, Gwangju, Republic of Korea. drydchoi@hanmail.net
authors.forename: Yoo Duk
authors.initials: YD
authors.lastname: Choi
authors.forename: Jin
authors.initials: J
authors.lastname: Choi
authors.forename: Jo Heon
authors.initials: JH
authors.lastname: Kim
authors.forename: Ji Shin
authors.initials: JS
authors.lastname: Lee
authors.forename: Jae Hyuk
authors.initials: JH
authors.lastname: Lee
authors.forename: Chan
authors.initials: C
authors.lastname: Choi
authors.forename: Ho Sun
authors.initials: HS
authors.lastname: Choi
authors.forename: Min Cheol
authors.initials: MC
authors.lastname: Lee
authors.forename: Chang Soo
authors.initials: CS
authors.lastname: Park
authors.forename: Sang Woo
authors.initials: SW
authors.lastname: Juhng
authors.forename: Jong Hee
authors.initials: JH
authors.lastname: Nam
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000096:biosynthesis / Q000235:genetics; D000328:Adult; D000368:Aged; D016889:Endometrial Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D053842:Microsatellite Instability; D018895:Microsatellite Repeats; D008875:Middle Aged; D000070957:MutL Protein Homolog 1; D051718:MutS Homolog 2 Protein / Q000096:biosynthesis / Q000235:genetics; D009687:Nuclear Proteins / Q000096:biosynthesis / Q000235:genetics; D016133:Polymerase Chain Reaction; D016159:Tumor Suppressor Protein p53 / Q000096:biosynthesis / Q000235:genetics
chemical_list: D048868:Adaptor Proteins, Signal Transducing; C501486:MLH1 protein, human; D009687:Nuclear Proteins; C495901:TP53 protein, human; D016159:Tumor Suppressor Protein p53; C497172:MSH2 protein, human; D000070957:MutL Protein Homolog 1; D051718:MutS Homolog 2 Protein