Assaying telomerase activity in three different malignant conditions in egyptian patients employing the polymerase chain reaction technique

الملخص EN

Background : telomerase enzyme adds hexameric repeats of ‘5-TTAGGG-3’ to the end of mammalian chromosomal DNA (telomeres) to compensate for the progressive loss that occurs with successive rounds of DNA replication.

Significant telomerase activity has been identified in human germline cells in neoplastic immortal somatic cells, in normal human lymphocytes and in stem cells, but not in most normal somatic cells, which senesce after a certain number of cell divisions.

Objective : the present study was conducted to examine telomerase activity in three different common malignant conditions in Egypt : 1) treated and untreated chronic myeloid leukemia (CML), 2) hepatocellular carcinoma (HCC) with and without type B or C viral hepatitis and 3) urinary bladder carcinoma (UBC) with and without bilhar-ziasis.

Material and Methods : in CML, twenty subjects were included in each group and results were compared to a control group of age-matched apparently normal individuals.

In HCC and UBC specimens were included in each group.

In CML cases, peripheral blood mononuclear cells were analyzed, while in HCC and UBC cases, tumor biopsy specimens were used.

Telomerase activity was estimated by polymerase chain reaction (PCR) followed by ELI-SA technique, which is a modification of the original telomerase repeat amplification protocol (TRAP).

This technique allows highly specific amplification of telome-rase-mediated elongation products combined with non-radioactive detection following an ELISA protocol.

Results: In CML, 85 % of untreated patients were te-lomerase positive which was significantly higher than treated patients (65 %) or control group (30 %).

In HCC, 57 % of cases were telomerase positive.

A significantly higher percentage of telomerase positive specimens were found among HCC cases associated with either HCV (75 %) or HBV (71.4 %) infection than in HCC cases alone (22.2 %).

In UBC, 69 % of patients were telomerase positive without differences between bilharzial and non-bilharzial cases.

Conclusion : elevated telomerase enzyme activity is associated with untreated or viral- complicated malignancies and can be used as an adjuvant to parameters used for monitoring tumor progression or the effect of therapy.