Detection of circulating carcinoma cells by telomerase activity

Telomerase has been shown to be a marker of epithelial cancer cells. We dev eloped a method that allows the detection of circulating carcinoma cells in the blood of cancer patients. Circulating epithelial cells are harvested f rom peripheral blood mononuclear cells by immunomagnetic separation using B erEP4-coated beads. A telomeric repeat amplification protocol (TRAP)-ELISA is then used to measure telomerase in harvested epithelial cells. This meth od is specific and sensitive as demonstrated by experiments using BerEP4-po sitive and negative cell lines. Whereas we never found telomerase activity in harvested epithelial cells (HEC) samples from 30/30 healthy donors, we h ave detected telomerase activity in HEC from 11/15 (73%) patients with stag e IIIB or IV non-small cell lung cancer (NSCLC) patients and from 8/11 (72% ) stage C or D (Dukes classification) colon cancer patients. This non-invas ive method could be of great value as a diagnostic or prognostic marker, or for monitoring cancer progression. (C) 2001 Cancer Research Campaign.