Telomerase activity in oral squamous cell carcinoma

Background: The riboprotein telomerase has been linked to cellular immortality and is believed to play a key role in tumorigenesis. Objective: To determine if telomerase is expressed in patients with oral squamous cell carcinoma. Design: Twenty patient samples of oral squamous cell carcinoma and 20 adjacent histologically normal mucosal samples were assayed using the telomeric repeat amplification protocol (TRAP) method 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 difference was observed in telomerase activity for T1 and T2 cancers compared with T4 cancers (P<.05 by analysis of variance). No statistically significant 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 key role in tumorigenesis. Further study is needed to determine the usefulness of this enzyme as a molecular marker.