TELOMERASE ACTIVITY IN ORAL SQUAMOUS-CELL CARCINOMA

Background: The riboprotein telomerase has been linked to cellular imm ortality and is believed to play a key role in tumorigenesis. Objectiv e: To determine if telomerase is expressed in patients with oral squam ous cell carcinoma. Design: Twenty patient samples of oral squamous ce ll carcinoma and 20 adjacent histologically normal mucosal samples wer e assayed using the telomeric repeat amplification protocol (TRAP) met hod for detection of telomerase activity. The leukemic tell line, K562 , was used as a positive control and the human fibroblast line, Hs21Fs , as a negative control. Patients: Consecutive series of patients with oral squamous cell carcinoma presenting to a tertiary referral center . Main Outcome Measure: A sample was classified as telomerase positive when an RNase-sensitive hexameric repeat ladder was observed. Absence of laddering was considered a negative result. Results: Eighteen (90% ) of 20 tumor samples and 7 (35%) of 20 adjacent histologically normal samples were telomerase positive. A statistically significant differe nce was observed in telomerase activity for T1 and T2 cancers compared with T4 cancers (P<.05 by analysis of variance). No statistically sig nificant difference was observed in activity for T1 and T2 cancers vs T3 cancers. Conclusions: The finding of telomerase activity in 90% of tumor samples is consistent with the concept of telomerase playing a k ey role in tumorigenesis. Further study is needed to determine the use fulness of this enzyme as a molecular marker.