Real-Time Quantification of Human Telomerase Reverse Transcriptase Mrna in Tumors and Healthy Tissues (Molecular Diagnostics and Genetics‪)‬

Body fluids, excrements, washings, or brushings (further summarized as bodily samples) are of interest in diagnostics because they can be obtained with minimally invasive or noninvasive techniques. For cancer diagnostics, mutant DNA derived from tumor cells has been found in feces (1), urine (2), sputum (3), pancreatic fluid (4), bile (5), cerebrospinal fluid (6), and plasma/serum (7,8) and currently is being evaluated for use in early detection, prognosis, and follow-up studies of malignant processes. Unfortunately, not all tumors have readily detectable DNA aberrations such as K-ras mutations. In contrast, they may contain mutations scattered over the gene, microsatellite instability, or loss of heterozygosity, which are more difficult to detect, especially when a marked background of DNA from healthy tissue is present. As an alternative to the detection of DNA aberrations, quantification of gene expression in cells shed in bodily samples has been used as a tumor marker (9,10). Telomerase activity is the most general molecular marker for the identification of human cancer and can be detected in 85% of all tumors, whereas most healthy tissues exhibit little or no telomerase expression (11,12). The enzyme needs at least two components to be functional: the RNA component, coded by the human telomerase RNA (hTR) gene (13), and the human telomerase reverse transcriptase subunit (hTERT [5] gene), which codes for the catalytic subunit of the enzyme (14-18). A method for the quantitative measurement of hTERT mRNA expression may be of interest for molecular diagnosis in tumors and corresponding bodily samples (19).