Telomerase activity, estrogen receptors (α, β), Bcl-2 expression in human breast cancer and treatment response

Tissue samples from 44 patients with breast cancer were used to assess telomerase activity using the TRAP method and the expression of ERα, ERβ and bcl-2 by means of immunocytochemical techniques.Telomerase activity was detected in 59% of the 44 breast tumors examined. Telomerase activity ranged from 0 to 49.93 units of total product generated (TPG). A correlation was found between telomerase activity and differentiation grade (p = 0.03). The only significant independent marker of response to treatment was clinical stage. We found differences between the frequency of expression of ERα (88%) and ERβ (36%) (p = 0.007); bcl-2 was expressed in 79.5% of invasive breast carcinomas. We also found a significant correlation between low levels of telomerase activity and a lack of ERβ expression (p = 0.03).Lower telomerase activity was found among tumors that did not express estrogen receptor beta. This is the first published study demonstrating that the absence of expression of ERβ is associated with low levels of telomerase activity.The mechanism for maintaining telomere integrity is controlled by telomerase, a ribonucleoprotein enzyme that specifically restores telomere sequences lost during replication by means of an intrinsic RNA component as a template for polymerization. Telomerase has 2 core functional components that are required for its activity the catalytic subunit of human telomerase reverse transcriptase (hTERT), and a telomerase RNA template (hTR). It is activated in most immortal cell lines in culture and in most malignant tumors [1] and is detected in 85–90% of human cancer specimens [2]. Telomerase activity is found in most tumor types including colorectal, breast, prostate, ovarian carcinomas and others. It also is increased in pre-invasive lesions of the breast, such as ductal carcinoma in situ (DCIS), suggesting that telomerase activity is activated early in breast carcinogenesis [3]. Among the telomerase subunits, TERT is concomitantly expressed with the