title: Telomerase activity and expression of the telomerase catalytic subunit, hTERT, in meningioma progression.
abstract: OBJECTIVE
  In recent reports, 6 to 19% of meningiomas have been classified as atypical or anaplastic/malignant. Some atypical and anaplastic meningiomas appear to arise from benign tumors by progression. Telomerase activation has recently been associated with malignant progression of human tumors. The authors have investigated a series of benign, atypical, and anaplastic/malignant meningiomas for telomerase activity and expression of the telomerase catalytic subunit human telomerase reverse transcriptase (hTERT).
  
  
  METHODS
  A quantitative telomeric repeat amplification protocol was used to detect telomerase enzyme activity in seven (21%) of 34 benign, but in nine (75%) of 12 atypical and in seven (100%) of seven anaplastic/malignant meningiomas. Very high levels of telomerase activity were observed only in highly aggressive tumors. Messenger (m)RNA expression of the catalytic subunit hTERT was found in 11 (33%) of 33 benign, 12 (92%) of 13 atypical, and all seven anaplastic/malignant tumors. All telomerase-positive lesions were also positive for hTERT mRNA, whereas no telomerase activity was detected in six (21%) of 29 hTERT-positive tumors. This indicates that upregulation of hTERT is the rate-limiting step for telomerase activation in the majority of meningiomas. Expression of telomerase and hTERT was seen in all four tumors with gross brain invasion. All recurrent tumors or meningiomas recurring during follow up expressed hTERT.
  
  
  CONCLUSIONS
  The results are consistent with a role for telomerase activation during the development of malignancy in meningiomas. Hence, expression of telomerase activity and hTERT might prove to be potentially useful markers for the evaluation of these tumors.
authors.affiliation: Neurochirurgische Universitätsklinik und Neuropathologisches Institut der Universität, Bonn, Germany. simonmat@mailer.meb.uni-bonn.de
authors.forename: M
authors.initials: M
authors.lastname: Simon
authors.forename: T W
authors.initials: TW
authors.lastname: Park
authors.forename: S
authors.initials: S
authors.lastname: Leuenroth
authors.forename: V H
authors.initials: VH
authors.lastname: Hans
authors.forename: T
authors.initials: T
authors.lastname: Löning
authors.forename: J
authors.initials: J
authors.lastname: Schramm
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000708:Anaplasia; D020134:Catalytic Domain / Q000235:genetics*; D004268:DNA-Binding Proteins; D018450:Disease Progression; D004789:Enzyme Activation; D005260:Female; D005500:Follow-Up Studies; D015971:Gene Expression Regulation, Enzymologic; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008297:Male; D008577:Meningeal Neoplasms / Q000201:enzymology* / Q000235:genetics / Q000473:pathology; D008579:Meningioma / Q000201:enzymology* / Q000235:genetics / Q000473:pathology; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D009364:Neoplasm Recurrence, Local / Q000201:enzymology / Q000235:genetics; D012313:RNA; D012333:RNA, Messenger / Q000235:genetics; D019098:Telomerase / Q000235:genetics* / Q000378:metabolism*; D015854:Up-Regulation
chemical_list: D004268:DNA-Binding Proteins; D012333:RNA, Messenger; C422952:telomerase RNA; D012313:RNA; D019098:Telomerase