Telomerase and Breast Cancer

Introduction: Telomerase is a ribonucleoprotein that compensates the shortening of the ends of eukaryotic chromosomes occuring during the cell cycle. Telomerase consists of two fundamental components, an RNA component (in humans, hTR or hTERc_ and a reverse transcriptase component (hTERT). hTR gene does not have any intron and requires specific strategies to determine its expression. Methods: Tumor samples from 46 patients with primary invasive breast cancer and patients with benign tumors were collected. The TRAP assay was used to detect telomerase activity. In order to detect low activity telomerase in samples with a negative telomerase activity on initial TRAP assay, a new strategy which was using the Re-PCR performance on TRAP products was evaluated. The expression of hTERT and its alternate splice variants were detected by RT-PCR. RT-PCR on cDNA and DNased cDNA samples and control groups was used to detect the expression of hTR, GAPDH and PGM1 genes (as housekeeping). Results: Performance of the standard TRAP assay demonstrated telomerase activity in 30 (62.5%0 out of 48 samples, but by using a repeat PCR (re-PCR) strategy, 6 (33%) out of 18 samples with an initial negative result had telomerase activity after re-PCR. The hTERT expression was revealed in 39 (81.3%). DNA contamination was detected in 34 (70.8%) of RNA samples. Without performing DNase treatment, 47 (97.9%) of all samples showed hTR expression, but with the application of this strategy, hTR expression decreased from 98% to 66.7%. In spite of finding no significant association between telomerase activity and hTERT expression, it was found by hTR expression (P