TELOMERASE COMPONENTS AS A DIAGNOSTIC-TOOL IN HUMAN ORAL LESIONS

Telomerase activity is considered to be a diagnostic marker of maligna ncy since most malignant cells express this activity and most somatic cells do not. However, the detection of telomerase activity is rather complicated and is affected by many factors. Recently, human telomeras e components were cloned and found to consist of 3 subunits. We assess ed which component of telomerase best correlates with malignancy in or der to study the possibilities for developing a new diagnostic: marker . Telomerase activity was measured by a telomeric repeat amplification protocol (TRAP) assay, and the telomerase components hTR, hTRT-mRNA a nd TPI-mRNA were detected by the reverse transcriptase-polymerase chai n reaction (RT-PCR). Twenty-five of 26 oral malignant lesions, 9 of 22 benign lesions and none of 19 normal control tissues exhibited distin ct telomerase activity. hTR and TPI-mRNA expression levels were detect ed in all malignant lesions and normal control tissues and had no sign ificant correlation with the telomerase activity results. In contrast, hTRT-mRNA expression was closely associated with telomerase activity. All lesions expressing hTRT were telomerase positive. In addition, so me samples of dysplastic lesions, benign tumors, lichen planus and nor mal mucosa exhibiting poor telomerase activity revealed weak expressio n of hTRT. Expression levels of hTRT-mRNA positively correlated with c linical and pathological findings. Detection of hTRT-mRNA by RT-PCR ap peared to be more sensitive for telomerase than measurement of telomer ase activity by the TRAP assay. Detection of hTRT-mRNA may provide inf ormation useful in the diagnosis of oral malignancies. (C) 1999 Wiley- Liss, Inc.