Lack of telomere maintenance during cell replication leads to telomere eros
ion and loss of function. This can result in telomere associations which pr
obably cause the dicentric chromosomes seen in some tumour cells. One mecha
nism of telomere maintenance in dividing cells is the action of telomerase,
a ribonucleoprotein enzyme that adds TTAGGG repeats onto telomeres and com
pensates for their shortening during cell division. Over 90 per cent of ext
racranial malignant neoplasms have been found to have telomerase activity.
This study sought to determine if there was a relationship between absence
of telomerase activity and presence of dicentric chromosomes in meningiomas
and to what extent the other main group of central nervous system tumours,
the gliomas, expressed telomerase activity, Telomerase activity was measur
ed on 25 meningiomas and 29 gliomas, Four of the meningiomas were atypical
variants and 11 were positive for dicentric chromosomes. Twenty-live of 29
gliomas were glioblastoma multiforme tumours, Measures were taken to ensure
absence of false positives due to primer-dimer interaction and false negat
ives due to protein degradation or the presence of Tag polymerase inhibitor
s. All 25 meningiomas and the four low-grade gliomas (WHO grade II) were te
lomerase activity-negative. Seven (28 per cent) of the 25 glioblastoma mult
iforme tumours showed telomerase activity. The absence of telomerase activi
ty in meningiomas and the high frequency of telomere associations support t
he hypothesis that these tumours are benign, transformed but pre-crisis. Th
e relatively low frequency of telomerase activity in the malignant glioblas
toma multiforme suggests that most of these tumours may have other mechanis
ms of telomere maintenance and that the potentially therapeutic telomerase
inhibitors will not be of great value in the future management of the major
ity of patients suffering from these tumours, Copyright (C) 1999 John Wiley
& Sons, Ltd.