Application of telomerase assay for the screening of cervical lesions

Telomerase is a ribonucleoprotein that synthesizes telomeric DNA onto chromosomal ends. The expression of telomerase is thought to be required for cellular immortality and oncogenesis. Telomerase activity has been detected not only in most cancers but also in some types of premalignant lesions, such as squamous intraepithelial lesions (SILs). In the present study, we used the telomerase assay to detect uterine cervical lesions in cervical scraping samples. A total of 82 cervical scraping samples were obtained from women with or without cervical lesions and examined by nonradioisotope telomeric repeat amplification protocol assay. Fifteen of 17 (88%) cervical cancer specimens exhibited telomerase activity, whereas 5 of 8 (63%) and 14 of 24 (58%) specimens from low-grade and high-grade SILs, respectively, also exhibited telomerase activity. In contrast, 3 of 33 (9%) specimens from normal cervices exhibited telomerase activity. Dilution telomeric repeat amplification protocol assay was performed to estimate telomerase activity; it revealed that high levels of activity were often expressed in cervical cancer. Cytological examination was also performed by Pap smear test, and 4 of 8 (50%) low-grade SILs, 21 of 24 (88%) high-grade SILs, and 16 of 17 (94%) cervical cancers were found to have cytological abnormalities. There were discordances in some cases between findings of smear abnormality and telomerase positivity. In particular, we found five cases of SILs without smear abnormality but with telomerase activity, suggesting that some lesions with false negative cytology can be detected by telomerase assay. These findings suggest that telomerase assay using cervical scrapings might be a useful screening method for cervical lesions especially when combined with a Pap smear test.