DIFFERENTIAL TELOMERASE EXPRESSION IN HUMAN PRIMARY INTRACRANIAL TUMORS

The telomeric repeat amplification protocol was used to detect express ion of telomerase in primary intracranial tumors. Expression was confi ned to high-grade variants; 10 of 19 glioblastoma multiforme tumors an d 5 of 5 primitive neuroectodermal tumors showed telomerase activity. Two of 8 anaplastic gliomas (1 anaplastic oligodendroglioma and 1 anap lastic oligoastrocytoma) were positive for telomerase. Of 16 meningiom as tested, only the 2 atypical variants were positive for telomerase. Two hemangiopericytomas of the central nervous system also showed expr ession of telomerase. Twenty-two pituitary adenomas (including 6 invas ive variants), 2 low-grade gliomas, 2 ependymomas, and 8 nonneoplastic brain specimens were negative. It was concluded that expression of te lomerase is found in mast glioblastoma multiforme tumors; primitive ne uroectodermal tumors appeared to be more uniformly positive. Expressio n of telomerase in atypical variants of meningioma and hemangiopericyt omas of the central nervous system correlated with the potential for a ggressive local growth and metastases. Despite the invasive tendency o f some pituitary adenomas, telomerase was not detected in these tumors , which suggests that other pathways account for their aggressive beha vior.