Integration of Molecular Biology and Morphology in Effusions with Focus on in situ Detection of Telomerase and its Components

Abstract: Clinical cytology is a rapid method to detect malignancy in effusions of the serous cavities, but the morphological characteristics of the cells do not always allow diagnosis and a specific marker for malignant cells would improve the diagnostic performance. Telomerase adds telomere repeats to the chromosome ends. It is the most promising universal indicator of malignancy and the project focuses on TRAP in situ, a unique PCR-based method to detect telomerase activity. With TRAP in situ we demonstrated telomerase activity in 95% of all malignant cell populations. Some mesothelial cells and lymphocytes showed weak reactivity. When compared with the results of TRAP using whole cell lysates we found that discrepant results could be due to cell composition and activity intensity in positive cells and we concluded that whole cell lysate TRAP is not a suitable method to detect telomerase in effusions. We further studied the relation between telomerase activity in malignant cells in effusions and prognosis and found that weak telomerase activity in tumor cells was associated with shorter survival times. A possible explanation is that cells with highly aggressive potential may find a way to preserve their telomeres in the absence of telomerase. Telomerase activity correlates to its catalytic subunit, hTERT and immunocytochemical detection of the hTERT protein is an attractive way to detect up regulation of telomerase. As telomerase activity was stronger in malignant than in mesothelial cells absolute quantification of the immunoreactivity would allow the identification of a cut-off level for malignancy. In a pilot study we showed that this could be achieved with time resolved fluorescence (TRF) imaging, a method that has never before been applied to cytological specimens.