Diagnostic usefulness of telomerase activity in nasopharyngeal carcinoma

Telomeres are specialized structures at the ends of eukaryotic chromosomes which are composed of simple repetitive G-rich hexameric sequences. Activat ion of telomerase, a ribonucleoprotein that synthesizes telomeric DNA, is f ound in most malignant tumors. However, little data is available concerning the correlation between telomerase activity and NPC (nasopharyngeal carcin oma). In this study, telomerase activation was determined using the TRAP (t elomerase repeat amplification protocol) assay in 62 nasopharyngeal biopsie s (25 NPC, 25 non-malignant nasopharyngeal lymphoid tissues, 12 post-irradi ated nasopharyngeal tissues). The results showed that strong telomerase act ivity was present in both NPC and non malignant nasopharyngeal biopsies. Po st-irradiated nasopharyngeal samples had a significantly lower telomerase a ctivity than NPC and non-malignant nasopharyngeal lymphoid tissues. It is w ell known that nasopharyngeal tissue is infiltrated by numerous lymphocytes , which might retain telomerase activity. Therefore, the finding that the t elomerase activation was lowest in post-irradiated nasopharyngeal tissues i s reasonable because of the destruction of activated lymphocytes and NPC by radiation. NPC biopsies with positive 12 mph node involvement exhibited hi gher levels of telomerase compared to those without lymph node involvement, Our data indicate a positive association between telomerase activity and t umor potential for lymphatic spreading in limited local tumors, In addition , telomerase activity may be useful as a diagnostic marker in the detection of tumor cells in recurrent NPC, but not in primary NPC.