%0 Journal Article
%T Telomerase activity, estrogen receptors (¦Á, ¦Â), Bcl-2 expression in human breast cancer and treatment response
%A Blanca Murillo-Ortiz
%A Horacio Astudillo-De la Vega
%A Sebastian Castillo-Medina
%A JM Malacara
%A Luis Benitez-Bribiesca
%J BMC Cancer
%D 2006
%I BioMed Central
%R 10.1186/1471-2407-6-206
%X Tissue samples from 44 patients with breast cancer were used to assess telomerase activity using the TRAP method and the expression of ER¦Á, ER¦Â 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 ER¦Á (88%) and ER¦Â (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 ER¦Â 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 ER¦Â 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¨C90% 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
%U http://www.biomedcentral.com/1471-2407/6/206