Evaluation of telomerase activation in head and neck cancer

During replication of the linear chromosomes, telomeres, i.e. the ends of the chromosomes, are not replicated completely by the conventional DNA polymerases. Therefore, normal somatic cells senesce after certain number of cell divisions. Telomerase is a special reverse transcriptase used by most eukaryotes to achieve immortalization. Telomerase activity has been determined in a variety of cancers. However, there are few reports on telomerase activity in head and neck cancer. The etiology of the disease in India is completely different from Western countries. Tobacco consumption is more prevalent in India and the mode of tobacco consumption (e.g. chewing, snuffing, bidi smoking, reverse smoking) is also different. The present study determined telomerase activity in 32 malignant tumour samples of head and neck cancer patients, 11 samples from patients with precancerous/benign lesions and 30 samples of adjacent normal tissues. Telomerase was found to be activated in 80% of the patients with head and neck cancer, 100% of the patients with precancerous/benign lesions and 74% of the adjacent normal tissues. According to the theory of field cancerization, carcinogenic insults (e.g. tobacco) may result into multiple malignant foci. This fact may explain the reason for high telomerase positivity in adjacent normal as well as precancerous/benign tissues. Telomerase activation and the clinical or histopathological characteristics of the head and neck cancer patients were observed to be independent features. This is a preliminary report which has generated a greater interest for in-depth elucidation of the role of telomerase and telomeres in head and neck carcinogenesis in India.