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 amplificatio
n protocol (TRAP) PCR ELISA kit in 41 cases of NPC, 14 cases of tissues adj
acent 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 hinds of normal control cells. The sensitivity and s
pecificity 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-neste
d PCR.
Results The telomerase activity was found increased in NPC and in tissues a
djacent to NPC with absorbance value (A value) of 1.15 U +/- 0.78 U and 1.0
4 U +/- 0.67 U respectively, compared with chronic nasopharyngitis (A = 0.1
8 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 involvem
ent (A = 1.02 U +/- 0.71 U), P < 0.05. The telomerase activity was also obs
erved 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 c
ontrast, 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 s
pecificity was also high (after inactivation by heat or RNase, the telomera
se activity was very tow).
Conclusions A high frequency of telomerase activity is commonly seen in NPC
, adjacent nasopharyngeal tissues, and HNE1 cell lines and is closely assoc
iated with NPC with cervical lymphnodes involvement. Both sensitivity and s
pecificity of the telomerase assay are high. However, owing to the fact tha
t the expression of hTR has no obvious difference between NPC and normal ti
ssues 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 ro
le of hTR in the carcinogenesis of NPC and on the exact relationship betwee
n hTR and telomerase is needed.