Purpose: Detection of loss of heterozygosity (LOH) has been described in various carcinomas on the basis of meticulous molecular techniques. Because of lack of simple and rapid techniques, LOH has not achieved common use in routine tumor diagnosis. A recently found variable number of tandem repeats (VNTR) segment in intron 1 of the p53 gene was described as highly polymorphic and therefore useful in detecting LOH. We used a rapid technique for detection of LOH in the p53 gene of patients with transitional cell carcinoma (TCC) of the bladder. The technique was based on the polymerase chain reaction (PCR) and agarose gel electrophoresis as described for other carcinomas previously. We evaluated whether TCC screening and surveillance could be performed detecting LOH in the urinary sediment.
Materials and methods: We investigated 29 patients with TCC of the bladder (pTa 12 patients; pT1 10 patients; pT2 - pT4 seven patients; grade 1 one patient; grade 2 19 patients; grade 3 nine patients). DNA was prepared by standard methods from white blood cells, tumor tissue, normal bladder mucosa, and urinary sediments. The amplification of the VNTR region was performed with PCR. PCR products were run in parallel lanes on 4.5% agarose gels.
Results: Of the 29 patients, 23 (79.3%) were found to have two different alleles ("informative cases") for the VNTR region. Of the 23 informative cases LOH was detected in the tumor tissue of 10 patients (43.5%). Referring to the total population 10 of 29 patients (34.4%) revealed LOH. In all patients with LOH in the tumor, LOH was also detected in the urinary sediment. LOH was not detected in the histologically benign bladder mucosa.
Conclusion: We present a simple and rapid technique based on PCR and agarose gel electrophoresis for the detection of LOH in tumor and urinary sediment of patients with TCC of the bladder. The ability to detect LOH not only in tumor tissue but also in urinary sediment offers an attractive approach for noninvasive diagnosis and surveillance of bladder cancer patients.