Molecular detection of telomerase-positive circulating epithelial cells inmetastatic breast cancer patients

The detection of circulating tumor cells and micrometastases may have impor tant therapeutic and prognostic implications. Telomerase is a hallmark of c ancer and is absent from normal epithelial cells. The aim of this study was to use telomerase activity as a molecular marker for the detection of canc er cells in blood of patients with breast cancer. Blood samples were collec ted from 25 women with stage IV breast cancer and 9 healthy volunteers, Per ipheral blood mononuclear cells were isolated by using Ficoll/Hypaque, Immu nomagnetic beads coated with an epithelial specific antibody (BerEP4) were used to harvest epithelial cells from peripheral blood mononuclear cells. T elomerase activity was detected in harvested epithelial cells (HECs) using two different telomerase-PCR-ELISA methods. HECs from blood samples of 21 o f 25 (84%) patients with breast cancer were telomerase positive. Telomerase activity was undetectable in HECs from the nine healthy volunteers, demons trating the specificity of the association between telomerase activity in H ECs and stage TV breast cancer. Thus, determination of telomerase activity in HECs appears to be a sensitive, specific, and noninvasive approach for d etecting circulating epithelial cancer cells in patients with metastatic br east cancer. This method could be of great value in monitoring the cancer c ell proliferation during chemotherapy. This study should be now extended to patients with early-stage breast cancer to investigate the role of telomer ase expression by HECs and to evaluate its prognostic value.