Expression of human telomerase subunit genes in primary lung cancer and its clinical significance

Background. Three major components of human telomerase, RNA component (hTERC), telomerase-associated protein (TEP1), and catalytic subunit (hTERT) have been cloned recently. The aim of this study was to examine the expression of these genes and to search for clinical usefulness. Methods. Expression of these genes was evaluated by reverse transcription-polymerase chain reaction in 92 human lung cancers and in 32 non-neoplastic lung tissues. In 15 patients, both telomerase activity by telomeric repeat amplification protocol assay and expression were evaluated. Results. hTERT expression was best associated with telomerase activity with a concordance of 77%. In 92 lung cancer tissues, hTERC, TEP1, and hTERT were expressed in 100%, 93%, and 89%, respectively. Whereas most adjacent non-neoplastic lung tissues expressed hTERC and TEP1 (94% and 100%, respectively), hTERT was detected in only 1 of 32 normal lungs. However, there was no relationship between hTERT expression and clinicopathologic features. Conclusions. hTERT expression can be a surrogate for telomerase activity that may serve as a novel biomarker of lung cancer with high specificity and sensitivity.