The significance of loss of 3q26. 1 small fragment in urothelial carcinoma of th bladder

Abstract

Objective To investigate the copy number changes on chromosome 3q26. 1 in urothelial carcinoma of the bladder, and to explore its potential clinical significance. Methods The microarray-based comparative genomic hybridization (Array-CGH) approach was used to analyze the genome-wide copy number changes of 35 tumor tissue samples of bladder cancer. To confirm the loss of a small fragment in 3q26. 1 detected by Array-CGH, real-time fluorescent quantitative polymerase chain reaction (real-time PCR) was performed with 57 frozen tumor tissue samples and 34 formalinfixed paraffin-embedded (FFPE) tumor tissue samples. The urine sediment cells collected from 15 healthy volunteers and 29 bladder cancer patients were checked as above. Results The Array-CGH data showed that the copy number loss of a small fragment in 3q26. 1 was detected in 77.1% (27/35)of the tumor tissue samples investigated. Real-time PCR analysis validated this loss of a small fragment of 3q26.1 with high frequencies in both 57 frozen tumor samples and 34 FFPE tumor samples.The percentage of samples exhibiting loss was 78.9% (45/57) and 100. 0% (34/34) respectively.Furthermore, the relative copy number of the 3q26.1 small fragment was significantly lower in the urinary sediment cells of the patients (median=0. 0020), comparing with that of healthy controls (median=0. 0030) (P＜0.01). Conclusions Loss of the small fragment in 3q26.1 could be a characteristic genetic change of urothelial carcinoma of the bladder. It may serve as a potential molecular marker for bladder cancer. Key words: Urinary bladder neoplasms; Carcinoma; DNA probes; Tumor markers, biological; DNA copy number