Telomerase reverse transcriptase catalytic subunit expression and proliferation index in Wilms tumor

Telomerase activity provides telomere maintenance in chromosomes. It prevents cells from entering senescence. Telomerase activity is one of the crucial steps in various cancers. Wilms tumor (nephroblastoma) is one of the most common solid tumors of childhood. Hitherto, telomerase reverse transcriptase (TERT) catalytic subunit expression in Wilms tumor has not been investigated widely. The aim of this study was to explore the expression level of human TERT in Wilms tumor and to correlate with some clinical prognosis factors such as tumor weight, stage, histology, and Ki67 expression. This study included 41 nephroblastoma cases of childhood. The telomerase catalytic subunit expression and proliferation index was determined using an immunohistochemical method on archival paraffin-embedded tissue sections. Statistical analysis was done on SPSS 9.05 by Mann-Whitney U test and Spearman's correlation analysis. TERT expression was negative in 11 cases (26.8%), weakly positive in 14 cases (34.1%), and strongly positive in 16 cases (39%). The proliferation index was found to be 20 to 90 (mean 58.9 +/- 26.8). Using Spearman correlation analysis, both the TERT expression (p = 0.032) and Ki67 index (p = 0.048) were found to be correlated with survival rate. Similarly, both the telomerase expression (p = 0.011) and the Ki67 index (0.040) were correlated with the weight and dimension of the tumor. But there was no relationship between telomerase expression and Ki67 index (p = 0.429). The mean survival time for telomerase negative cases was 56.6 +/- 27.3 months, while it was 34.67 +/- 28.36 months for positive cases. The Mann-Whitney U test revealed that levels of telomerase (p = 0.040) significantly affected the survival rate. In the present study, we showed that the presence of TERT expression correlated with both tumor size and survival time. These findings suggest that senescence may play an important role in WT evolution, and determination of telomere maintenance will be useful to predict survival and follow-up of patients with Wilms tumor.