TELOMERASE EXPRESSION AND ACTIVITY IN ENDOMETRIAL CANCER
Telomerase is an enzyme, the activity of which is detectable in 85–90% of human cancers and its activation may be crucial for the growth of cancer cells. Human telomerase consists of catalytic subunit (hTERT), RNA subunit (hTR) and associated proteins. To evaluate telomerase as a diagnostic factor in endometrial cancer, we tested activity of telomerase and the expression of hTERT and hTR genes. Samples of normal and tumor tissue from endometrial cancer patients were obtained from 40 postmenopausal women. The activity of telomerase was assessed by a PCR-based telomere repeat amplification protocol assay (TRAP). hTR and hTERT genes expression was evaluated by reverse transcriptase polymerase chain reaction (RT-PCR) with GAPDH as an indirect marker of tissue integrity. 39 (97.5%) of 40 cancerous samples were telomerase positive, whereas only 16 (40%) of 40 control samples exhibited telomerase activity. None of the 40 normal samples had high telomerase activity (after 100-fold dilution) and only one of cancer samples exhibited low activity not detected after 10-fold dilution. The distribution of telomerase activity in normal and cancerous endometrium groups differed significantly (p < 0.001). hTR expression was found in 37 (93%) of 40 endometrial cancer samples, whereas 33 (83%) of 40 samples displayed expression of hTERT. In normal endometrium these values were 31 (78%) and 9 (22%), respectively. Our results suggest that the appearance of endometrial cancer may be associated with the expression of human telomerase catalytic subunit, hTERT and human telomerase RNA, hTR. Therefore, coupled expression of hTERT and hTR may be considered as a diagnostic marker of endometrial cancer. Endometrial cancer may be also associated with telomerase activation, but low activity of the enzyme may also be detected in non-cancerous endometrium.
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