TELOMERE LENGTH, TELOMERASE ACTIVITY AND TELOMERE-BINDING PROTEINS IN PAPILLARY BLADDER UROTHELIAL CARCINOMAS: COMPARISON WITH GRADING AND RISK OF RECURRENCE

OBJECTIVE To evaluate the relationship between telomere length (TL), telomerase activity and telomere-binding proteins (TBP), and tumour grade and recurrence (RR) in patients with papillary urothelial non-muscle invasive bladder cancer (NMIBC). PATIENTS AND METHODS Samples of tumours and disease-free bladder mucosa were collected from 35 patients with papillary urothelial NMIBC and samples of healthy urothelium were collected from 23 control patients. All samples were processed to determine the presence and grade of papillary urothelial BC; and the presence of TL (by Southern blot), telomerase activity (expression of hTERT) and expression of several TBP (TRF1, TRF2, PARP1 and TANK; by Western blotting). Cystoscopy was performed at 3, 6 and 12 months to determine disease recurrence. RESULTS Histology determined that 15 patients (42.9%) had high grade (HG) and 20 (57.1%) had low grade (LG) papillary urothelial NMIBC. Control patients differed significantly (P <0.05) in all parameters except TRF2 expression when compared HG and LG tumors. Despite having similar TL, disease free mucosa of cancer patients differed significantly (P <0.05) from HG and LG tumors in all TBP. Subjects in control group differed significantly in all parameters including TL. During the follow-up, a total of 11 tumour recurrences were observed, 8 in patients originally diagnosed with HG tumours and 3 in patients with LG tumours. TL, hTERT and PARP-1, in tumour samples, were positively associated (p<0.05) with RR. TRF1, TRF2, and TANK expression levels in samples of normal mucosa from the tumour group were negatively associated (P < 0.05) with RR. In samples of unaffected mucosa from the tumour group, all parameters differed significantly from the control group (P < 0.05). DISCUSSION More than 70% of urothelial BC recur after resection, and about 15% of them progress to invasive stages. The identification of prognostic markers, to serve as predictors of progression risk and/or recurrence in patients with superficial BC, is desirable. We found significant reductions in TL. We found shorter telomeres in HG tumours samples that those in LG carcinomas, a significant lower expression of TRF1 and TRF2 and a significant higher expression of TANK and PARP-1. Moreover, the precocity of recurrence was higher in patients who had shorter telomeres and higher values of hTERT and PARP-1. All of the molecular parameters, in samples of unaffected mucosa from NMIBC patients, differed significantly from control samples. This supports the notion that BC is not exclusively a disease of the tumour site but can be considered a disease of the entire urothelium, wich is highly unstable, and confirms the potential for multifocal recurrence, common in cases of bladder cancer. CONCLUSIONS TL plays a crucial role in carcinogenesis of urothelial cells. Telomere instability appears to result from dysfunction of some TBP, which enables telomerase lengthening. .