Abstract
Telomerase, a ribonucleoprotein enzyme, is expected to be a new marker for cancer diagnosis. TRAP (the telomeric-repeat amplification protocol) developed by Kim et al. is a sensitive method to detect telomerase activity. Telomerase activity is detected by TRAP in most malignant cells in vivo and in vitro, but it is not found, or found only in very low amounts, in normal somatic cells and tissues. TRAP and its modified protocols are, however, not always suitable for measuring the activity of a large number of clinical samples to diagnose cancer, because they generally require a time-consuming detection step such as gel electrophoresis with radioactive materials. To improve the procedure for mass diagnosis, we applied a hybridization protection assay (HPA) to replace the detection step. HPA, which employs an acridinium-ester-labelled probe, is radioactivity-free, easy to handle without electrophoresis, quick, and applicable to a quantitative format. In this work we have established and demonstrated the advantages of TRAP/HPA. The telomerase activity of various primary and established cells, differentiating cancer cells, and normal and tumour colorectal and liver tissues was quantitatively analysed by TRAP/HPA. The results indicate that HPA combined with TRAP is a rapid and simple method, easy to handle and quantify, for the clinical diagnosis of cancer.