title: Telomerase activity and cytokeratin 20 as markers for the detection and followup of transitional cell carcinoma: an unfulfilled promise.
abstract: OBJECTIVE
  Telomerase activity compensates for the erosion of chromosomes and it has been detected in a wide variety of human tumors. Cytokeratin 20, an intermediate filament of epithelial cells, is expressed particularly in the urinary tract. These 2 molecules are candidates to become markers for the detection and followup of bladder carcinoma. We evaluate whether each molecule may serve as a potential marker and whether the 2 combined would improve the detection or followup of bladder carcinoma in a noninvasive manner.
  
  
  METHODS
  We obtained 44 morning urine samples from patients with transitional cell carcinoma patients and 26 from age matched patients with a wide variety of clinical disorders but no malignancy of any kind. A telomerase polymerase chain reaction-enzyme-linked immunosorbent assay kit was used to determine telomerase activity and cytokeratin 20 expression was determined by nested reverse transcriptase-polymerase chain reaction.
  
  
  RESULTS
  All samples tested positive for cytokeratin 8 expression, which verified epithelial cells in the urine samples. Of the 44 transitional cell carcinoma cases of all stages and grades 37 (84.1%) were positive for telomerase activity, 36 (81.8%) were positive for cytokeratin 20 expression and 65.9% were double positive. Of the 29 controls with various clinical conditions other that malignancy 22 (75.9%) were positive for telomerase activity, 13 (44.83%) were positive for cytokeratin 20 expression and 34.6% were double positive.
  
  
  CONCLUSIONS
  Telomerase activity and cytokeratin 20 expression are not specific for malignancy and may be detected in many nonmalignant pathological conditions. Therefore, their use as potential markers of bladder carcinoma should be carefully reevaluated.
authors.affiliation: Hematology Laboratory, Immunology Research Unit and Department of Urology, Lady Davies Carmel Medical Center, Haifa, Israel.
authors.forename: A
authors.initials: A
authors.lastname: Cassel
authors.forename: M A
authors.initials: MA
authors.lastname: Rahat
authors.forename: N
authors.initials: N
authors.lastname: Lahat
authors.forename: N
authors.initials: N
authors.lastname: Lindenfeld
authors.forename: Y
authors.initials: Y
authors.lastname: Mecz
authors.forename: A
authors.initials: A
authors.lastname: Stein
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor; D002295:Carcinoma, Transitional Cell / Q000201:enzymology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007381:Intermediate Filament Proteins; D053554:Keratin-20; D008297:Male; D019098:Telomerase / Q000378:metabolism*; D001749:Urinary Bladder Neoplasms / Q000201:enzymology*
chemical_list: D014408:Biomarkers, Tumor; D007381:Intermediate Filament Proteins; C507499:KRT20 protein, human; D053554:Keratin-20; D019098:Telomerase