Telomerase assay as a possible predictor of the response to anticancer chemotherapy

Background: The correlation between telomerase activity and antitumor effects was investigated in cell lines of human gastric (MKN-28, MKN-45, and MKN-74) and breast (T-47D, MCF-7, ZR75-I) cancers to evaluate the possibility of utilizing this enzyme to predict tumor response to chemotherapy. Materials and Methods: After culture with various concentrations of 5-fluorouracil (5-FU) or doxorubicin (DOX) for 3 days, cell viability (trypan blue exclusion), cell cycle distribution (flow cytometry), and telomerase (TRAP-EZE) were measured. Results: Telomerase activity correlated significantly with the number of viable cells. After drug exposure, this activity decreased rapidly in a dose-dependent fashion in most cell lines. There was no correlation between telomerase activity and the distribution of cells in the cell cycle. Conclusions: As the assay for telomerase activity is extremely sensitive and is virtually specific to cancer cells, this method may prove useful for the sensitivity testing of small specimens of human tumors.