[Expression of telomerase and its RNA in nasopharyngeal carcinoma]

Abstract

Objective: To study the activity of telomerase and the expression of its RNA in nasopharyneal carcinoma (NPC) and HNE1 cell lines of NPC.

Methods: Telomerase activity was detected with telomeric repeat amplification protocol (TRAP) PCR ELISA kit in 41 cases of NPC, 14 cases of tissues adjacent to the carcinoma, and 19 cases of chronic nasopharyngitis, HNE1 cell lines of NPC, HL60 cell lines of leukemia, TUL1 cell lines of lung cancer, as well as three other kinds of normal control cells. The sensitivity and specificity of telomerase assay were also analyzed. Moreover, the expression of human telomerase RNA (hTR) was studied in 27 cases of NPC, 19 cases of adjacent nasopharyngeal tissues, and 17 cases of control groups by RT-nested PCR.

Results: The telomerase activity was found increased in NPC and in tissues adjacent to NPC with absorbance value (A value) of 1.15 U +/- 0.78 U and 1.04 U +/- 0.67 U respectively, compared with chronic nasopharyngitis (A = 0.18 U +/- 0.09 U). In NPC with cervical lymphnodes involvement the telomerase activity (A = 1.25 U +/- 0.79 U) was higher than in those without involvement (A = 1.02 U +/- 0.71 U), P < 0.05. The telomerase activity was also observed in HNE1 cell lines (A = 1.26 U +/- 0.97 U) and in other two kinds of cancer cell lines, but not in the three kinds of normal control cells. By contrast, no significant difference was seen in the expression of hTR among the three nasopharyngeal biopsy groups (P > 0.05). Finally, the sensitivity of telomerase assay was high (at an amount of 10(2) HNE1 cells), and the specificity was also high (after inactivation by heat or RNase, the telomerase activity was very low).

Conclusions: A high frequency of telomerase activity is commonly seen in NPC, adjacent nasopharyngeal tissues, and HNE1 cell lines and is closely associated with NPC with cervical lymphnodes involvement. Both sensitivity and specificity of the telomerase assay are high. However, owing to the fact that the expression of hTR has no obvious difference between NPC and normal tissues and does not always correspond with the telomerase activity, it would be better to do TRAP as well as hTR assays for the activity and expression in assessing the carcinogenesis of NPC. So, more intensive study on the role of hTR in the carcinogenesis of NPC and on the exact relationship between hTR and telomerase is needed.