title: Elevated microsatellite instability at selected tetranucleotide repeats does not correlate with clinicopathologic features of bladder cancer.
abstract: BACKGROUND
  The aim of the present study was to evaluate whether elevated microsatellite instability (MSI) at selected tetranucleotide repeats (EMAST) is associated with clinicopathologic and molecular parameters in urinary bladder cancer (BC).
  
  
  METHODS
  A consecutive series of 117 nonselected urothelial BCs was studied. Microsatellite analysis and detection of loss of heterozygosity (LOH) was performed after microdissection by using 12 markers selected for sensitive detection of EMAST. Furthermore, five markers (BAT25, BAT26, D2S123, APC, and D17S250) of the Bethesda consensus panel for detection of colorectal cancer within the hereditary non-polyposis colon cancer syndrome (HNPCC) were analyzed. Expression of TP53 and mismatch repair (MMR) proteins hMSH2, hMLH1, and hMSH6 was investigated by immunohistochemistry.
  
  
  RESULTS
  EMAST was detected in 10 of 117 patients (8.5%), whereas MSI in the HNPCC panel was found in one of 114 cases (0.9%). LOH in EMAST markers was seen in six of 114 (5.3%) cases. All tumours showed normal expression of hMSH2 and hMLH1. Overexpression of TP53 was observed in nine of 117 evaluated cases (7.7%). No association of EMAST and TP53 expression could be demonstrated. None of the clinicopathologic or molecular parameters were associated with EMAST.
  
  
  CONCLUSIONS
  EMAST is another distinct form of MSI in urothelial BC. However, EMAST seems to be a rare event in non-selected urothelial BC and does not seem to be associated with commonly used clinicopathologic and clinical features in patients with BC.
authors.affiliation: Department of Urology, University of Regensburg, Germany. maximilian.burger@klinik.uni-regensburg.de
authors.forename: Maximilian
authors.initials: M
authors.lastname: Burger
authors.forename: Sarah J
authors.initials: SJ
authors.lastname: Burger
authors.forename: Stefan
authors.initials: S
authors.lastname: Denzinger
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Wild
authors.forename: Wolf F
authors.initials: WF
authors.lastname: Wieland
authors.forename: Hagen
authors.initials: H
authors.lastname: Blaszyk
authors.forename: Ellen C
authors.initials: EC
authors.lastname: Obermann
authors.forename: Robert
authors.initials: R
authors.lastname: Stoehr
authors.forename: Arndt
authors.initials: A
authors.lastname: Hartmann
mesh_terms: D006801:Humans; D053842:Microsatellite Instability; D018895:Microsatellite Repeats; D011446:Prospective Studies; D001749:Urinary Bladder Neoplasms / Q000235:genetics* / Q000473:pathology*