Microsatellite alterations in human bladder cancer: detection of tumor cells in urine sediment and tumor tissue.
OBJECTIVE
Bladder cancer is the result of clonal expansion of cancer cells in which multiple genetic alterations have occurred. Loss of heterozygosity (LOH) studies have demonstrated that alterations in microsatellite regions are common in bladder cancer. This observation offers the possibility of early tumor detection by examining the DNA of urinary sediment.


METHODS
We investigated alterations of 17 microsatellite loci in urinary bladder carcinomas of different stages and grades. Per locus, 19-30 specimens were evaluated. DNA was isolated from tumor specimens, urinary sediment and peripheral blood lymphocytes. DNA fragments of 17 microsatellite loci were amplified by PCR and analyzed for genomic alterations.


RESULTS
Microsatellite alterations were detected in tumor tissue and urine sediment from 27 out of 31 patients (87%). Urine sediment analysis alone proved positive in 24 out of 31 patients (77%). The type of lesions most frequently detected was LOH (74% of all alterations), followed by length alteration (24%) and additional alleles (2%). On average, the alteration frequency was 22% per locus. The loci at chromosomes 9 and 18 proved most informative. No alterations were found in grade I tumors. The study revealed a correlation between microsatellite alterations and the respective grades and stages of the tumors. Average alteration frequencies per locus were: 27.4% in grade III versus 19.3% in grade II tumors, 26.5% in invasive versus 12.3% in superficial tumors.


CONCLUSIONS
Our results demonstrate that microsatellite alterations are common in bladder cancer and that analysis of genomic instabilities in urine samples should be further evaluated as a method for bladder cancer screening in a high-risk group. Especially, when a set of microsatellites is used that shows a high probability of detecting alterations and allows easy handling, this could be an alternative or a completion to currently available methods.
Berger
Andreas P
AP
Department of Urology, University of Innsbruck, Anichstrasse 35, A-6020 Innsbruck, Austria. andreas.p.berger@uibk.ac.at
Parson
Walther
W
Stenzl
Arnulf
A
Steiner
Hannes
H
Bartsch
Georg
G
Klocker
Helmut
H
D002295:Carcinoma, Transitional Cell / Q000737:chemistry / Q000175:diagnosis* / Q000235:genetics* / Q000652:urine; D004273:DNA, Neoplasm / Q000652:urine*; D006801:Humans; D019656:Loss of Heterozygosity / Q000235:genetics*; D018895:Microsatellite Repeats / Q000235:genetics*; D009364:Neoplasm Recurrence, Local / Q000473:pathology / Q000652:urine; D016133:Polymerase Chain Reaction; D001749:Urinary Bladder Neoplasms / Q000737:chemistry / Q000175:diagnosis* / Q000235:genetics* / Q000652:urine
D004273:DNA, Neoplasm