Increased telomerase activity and absence of p53 mutation in oligo-astrocytomas induced by N-ethyl-N-nitrosourea in rats

The question of whether the changes in telomerase activity and/or the alteration of the p53 gene are involved in the development of oligo-astrocytomas induced by N-ethyl-N-nitrosourea (ENU) in rats was addressed. Telomerase activity levels of oligo-astrocytomas, including early neoplastic lesions, were significantly increased as compared to the normal controls, correlating with the degree of malignancy. In contrast, no mutations of p53 exons 5–7 were found in early neoplastic lesions or oligo-astrocytomas. These results indicate that the activation of telomerase occurs during astrocytoma carcinogenesis and contributes to the development of brain tumors, but the alterations of p53, at least on exons 5–7, may not be involved in this process.