Expression of telomerase RNA in oesophageal and oral cancer

Background. Telomerase is detectable in 85% of cancers, but is largely repressed in normal tissues. Human telomerase RNA (hTR) inhibition is a promising anti-cancer strategy, but requires differential expression between malignant and normal tissue. Method: Archival paraffin sections from 48 oral squamous cell carcinomas (SCC) (23 floor of mouth, 25 tongue) and 56 oesophageal carcinomas (41 SCC, 15 adenocarcinomas) were evaluated for hTR expression using a radiolabelled riboprobe. Results were compared with expression in controls and adjacent histologically normal tissue. Statistical analysis was by the chi (2) test. Results: hTR was detectable in 76% of oral SCC overall (floor of mouth 65%, tongue 88%, P = 0.61), and in 54% of oesophageal cancers (SCC 51%, adenocarcinoma 60%, P = 0.56). Detectable hTR expression was significantly more frequent in oral SCC than oesophageal SCC (P = 0.01). hTR expression was only detected in normal tissue at low levels in basal squamous epithelium. There was agreement of hTR expression between 8/9 surgically excised carcinomas and their initial diagnostic biopsies. Conclusion: Tumour-specific hTR expression confirms hTR inhibition as a possible therapeutic strategy in some if not all oesophageal and oral cancers. Generally concordant hTR status between biopsy and resection suggest that biopsy may have a role in selecting candidates for telomerase inhibition therapy.