Reactivation of telomerase in squamous epithelial carcinomas in the area of the head and neck

Abstract

Head and neck cancer development involves the accumulation of multiple cellular alterations over a long period of time. Selection and expansion of altered cell clones can lead to the evolution of a malignant phenotype. The theory of carcinogenesis suggests that unlimited cell proliferation is required for development of malignant disease and cancer must attain immortality for progression to malignant states. One step in the immortalization process may be the reactivation of telomerase. This enzyme complex can prevent the continuous shortening of telomeres which is observed at each cell cycle. Telomerase activity was detected in 68% of squamous cell carcinomas of pharynx and larynx and 58% of histologically tumor-free resection margins. Recurrences occurred with a higher rate in cases with telomerase positive primary tumor. The importance of telomerase activity in histologically negative resection margins needs further investigations. Telomerase activity was found in 90% of corresponding lymph nodes without any correlation to metastasis in the lymph node. The reactivation of telomerase seems to be an important step in carcinogenesis of head and neck cancers. Further studies are necessary in order to understand the role of the enzyme as a possible marker for tumor progression and clinical outcome.