title: Telomerase activity in benign and malignant thyroid diseases.
abstract: BACKGROUND
  Telomerase, an enzyme associated with cellular immortality, is expressed by most malignant cells and is inactive in most normal somatic cells, with the excitation of proliferative stem cells, male germ cells, and activated lymphocytes. The measurement of telomerase activity in clinically obtained tissue samples may provide useful information as both a diagnostic and prognostic marker. In this study, we sought to determine whether telomerase activity might prove helpful in the assessment of benign and malignant thyroid tumors.
  
  
  METHODS
  A modified, semiquantitative polymerase chain reaction-based telomeric repeat amplification protocol assay was used for detection of telomerase activity in 59 samples obtained at thyroidectomy, including 15 thyroid cancers, 22 benign thyroid diseases, and 22 adjacent normal thyroid tissues.
  
  
  RESULTS
  Four of 13 differentiated thyroid carcinomas (30%) and 2 of 2 medullary carcinomas (100%) expressed telomerase activity. Unexpectedly, we also detected activity in 3 of 22 (14%) adjacent normal thyroid tissues and 6 of 22 (28%) benign thyroid diseases. Pathologic review of the telomerase-positive benign specimens revealed that many contained extensive lymphoid infiltrates with germinal centers (six of nine, 67%), as did two of four telomerase-positive papillary carcinomas.
  
  
  CONCLUSIONS
  In contradistinction to other epithelial carcinomas, telomerase does not appear to be frequently reactivated in differentiated thyroid carcinomas.
authors.affiliation: Hamon Center for Therapeutic Oncology Research, University of Texas Southwestern Medical Center, Dallas, USA.
authors.forename: K
authors.initials: K
authors.lastname: Yashima
authors.forename: F
authors.initials: F
authors.lastname: Vuitch
authors.forename: A F
authors.initials: AF
authors.lastname: Gazdar
authors.forename: T J
authors.initials: TJ
authors.lastname: Fahey
mesh_terms: D000328:Adult; D000368:Aged; D004789:Enzyme Activation; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D019098:Telomerase / Q000378:metabolism*; D013959:Thyroid Diseases / Q000201:enzymology* / Q000473:pathology; D013964:Thyroid Neoplasms / Q000201:enzymology* / Q000473:pathology
chemical_list: D019098:Telomerase