Telomerase reverse transcriptase, TERT

Telomerase is a ribonucleoprotein polymerase which adds repeated telomeric DNA sequences, TTAGGG, to the ends of chromosomes. Telomerase activity is required for sustained cell division, being present in stem cells, germ cells, malignant cells and immortalised cell lines but not in normal somatic cells. Telomerase consists of a RNA moiety, human telomerase RNA component (hTERC), which acts as a template and a protein moiety, the human telomerase reverse transcriptase, hTERT3. A third component, telomerase-associated protein (TEP1), is ubiquitous and does not correlate with levels of telomerase activity3. A number of previous biochemical studies have demonstrated telomerase in a range of malignant cells. The presence of hTERC can be demonstrated by Northern blot analysis or ins-situ hybridisation and is present predominantly in cancer cells3. The presence of TERT can be demonstrated by immunohistochemistry on formalin-fixed, paraffin-embedded tissues: staining is nuclear.

Immunohistochemical expression

benign mesothelial proliferation

0/31

pleuritis

0/161

malignant mesothelioma

67/681
 

The study of only three cases of benign mesothelial proliferation is clearly inadequate, giving 95% confidence limits of 0-71%.

Increased telomerase activity is associated with poorer survival in colorectal carcinoma2.

In the lung, there is a progressive increase in hTERC and hTERT mRNA from low-grade atypical adenomatous hyperplasia to high-grade atypical adenomatous hyperplasia to non-mucinous bronchiolo-alveolar carcinoma3.

Diagnostic utility

References

1Kumaki, F., Kawai, T., Churg, A., Galateau-Salle, F. B., Hasleton, P., Henderson, D., Roggli, V., Travis, W. D., Cagle, P. T., Ferrans, V. J. Expression of Telomerase Reverse Transcriptase (TERT) in Malignant Mesotheliomas. Am J Surg Pathol 2002; 26:365-370

2Wei, R. and Younes, M. Immunohistochemical detection of telomerase reverse transcriptase in colorectal adenocarcinoma and benign colonic mucosa. Hum Pathol 2002;33:693-6.

3Nakanishi, K., Kawai, T., Kumaki, F., Hirot, S., Mukai, M. and Ikeda, E. Expression of human telomerase RNA component and telomerase reverse transcriptase mRNA in atypical adenomatous hyperplasia of the lung. Hum Pathol 2002;33:697-702.

This page last revised 22.3.2003.

©SMUHT/PW Bishop