Detection of human telomerase reverse transcriptase messenger RNA in urine of high risk patients as a non invasive molecular diagnostic tool for urinary bladder cancer in Egyptians

ABSTRACT

Bladder cancer is an important national health problem as it is the leading cancer in men in Egypt. Cystoscopy and biopsy, currently remains the gold standard procedure for diagnosis, yet, it is invasive and costly. Urinary cytopathology remains to be the only non-invasive alternative method for diagnosis. Although it is tumour specific, yet it has a poor sensitivity, especially for low grade tumours. Detection of Telomerase enzyme in exfoliated urinary cells is a potentially good molecular diagnostic marker in bladder cancer, since the catalytic subunit of this enzyme [hTERT] proved to be essential for cellular immortality and oncogenesis. The study comprised 39 patients [36 with urothelial carcinomas and 3 cases were squamous cell carcinoma] with bladder cancer and 22 non cancer control [including 14 patients with benign urological disorders and 8 healthy volunteers]. The urine sample was split into two aliquots one was used to undertake RNA extraction and hTERT/GAPDH RT-PCR semi-quantitative assay and the second for cytological examination. Cystoscopy was considered the reference standard for the identification of bladder cancer. The hTERT/GAPDH RT-PCR test showed significantly higher diagnostic sensitivity than cytology [84% Vs. 75% p<0.008] for confirmed UCC, particularly for low grade non-muscle invasive UCC [82% Vs. 64% p<0.005]. On combining the two tests a sensitivity of 95% was obtained. A positive hTERT expression was detected 4-5 months earlier than cystoscopic evidence of recurrence in 2 patients during their follow up. In this pilot study, detection of hTERT expression in urine has shown to be a more sensitive marker for diagnosis of bladder cancer than cytology. The combination of urinary hTERT mRNA with cytological testing augments the sensitivity for the non-invasive early diagnosis of bladder cancer. This finding warrants further extended study to validate the potential role of hTERT expression as a diagnostic non invasive tool for high risk patients and detection of recurrence in bladder cancer in Egypt