Telomerase activity and expression of human telomerase RNA component and human telomerase reverse transcriptase in lung carcinomas

The aim of this study was to evaluate the usefulness of determination of te lomerase activity and expression of human telomerase RNA component (hTERC) and human telomerase reverse transcriptase (hTERT) for the diagnosis of lun g carcinomas. The tissues studied consisted of 115 carcinomas and adjacent nonneoplastic lung, which were removed surgically without previous chemothe rapy or radiotherapy. Telomerase activity was determined using a semiquanti tative polymerase chain reaction-based telomeric repeat amplification proto col (TRAP) assay. The results obtained were classified into high and low te lomerase groups. Localization of expression was examined by using in situ h ybridization and immunohistochemistry. The correlation between telomerase a ctivity in lung carcinoma and clinicopathologic features, including prognos is, was investigated. Telomerase activity in lung carcinomas was detected i n 107 of 115 (93%) lung carcinomas, but not in any adjacent noncancerous ti ssues, and was significantly higher in small cell carcinoma than in any oth er histologic type. This activity also was significantly higher in poorly d ifferentiated than in well-differentiated squamous cell carcinomas and aden ocarcinomas. The overall survival rate (P = .020) was significantly lower i n the high telomerase group. Messenger RNAs for hTERC and hTERT were mainly detected in the cytoplasm of cancer cells by in situ hybridization, and TE RT protein was localized in the nuclei of these cells by immunohistochemica l staining. Determinations of telomerase activity by in situ hybridization, immunohistochemistry, and TRAP assay are useful for evaluating the diagnos is and prognosis of lung carcinomas. HUM PATHOL 32:188-195. Copyright (C) 2 001 by W.B. Saunders Company.