Utility of Competitive Reverse Transcription-Polymerase Chain Reaction Analysis of Specific CD44 Variant RNA for...

Recently, we developed a novel molecular approach, CD44 v8-10/CD44 v10 competitive reverse transcription-polymerase chain reaction (CC-RT-PCR), to detect a sparse population of cancer cells overexpressing CD44v8-10 among a much larger population of nonneoplastic cells in body fluids by the measurement of the transcriptional level of CD44v8-10 relative to that of CD44v10. We have shown the utility of CC-RT-PCR in diagnosing disease using urine samples from patients with bladder cancer. In this study, we initially examined the expression of CD44 splice variants in human upper urinary tract transitional-cell carcinomas (UUT-TCCs) and their adjacent normal urinary tissues by RT-PCR. Any CD44 variant isoforms were barely detectable in normal urinary tissues, whereas CD44v8-10 was predominantly expressed in 21 of the 25 UUT-TCC specimens (84%). We then applied CC-RT-PCR to spontaneously voided urine samples from 40 patients with UUT-TCC and 40 patients with benign urologic diseases. The CC-RT-PCR analysis revealed that all of the samples from patients with benign diseases presented a predominant expression of the CD44v10 transcript, whereas 26 of the 40 samples from patients with UUT-TCC dominantly expressed the CD44v8-10 transcript. In addition, the positive rate obtained by the CC-RT-PCR analysis was significantly higher than that obtained by cytologic examination, especially in patients with low-grade UUT-TCC. These findings strongly suggest that CC-RT-PCR is a useful noninvasive tool for the diagnosis of UUT-TCC.