title: Comparison of telomerase levels before and after differentiation of two cell lines of human neuroblastoma.
abstract: BACKGROUND
  Telomerase is the enzyme that is responsible for maintaining telomere length in human germ cells, tumor cells, and immortalized cells. Its specific role in the immortilization process is unknown. This study was performed to determined whether the level of telomerase activity in human neuroblastoma cell lines correlated with their level of differentiation. We proposed that as neuroblastoma cells differentiated into more mature or benign cells, the levels of telomerase expression would decrease.
  
  
  METHODS
  Two human neuroblastoma cells lines, SK-N-AS and SK-N-DZ, were differentiated using retinoic acid. These cells were assayed for telomerase activity by the telomere repeat amplification protocol (TRAP) before, during, and after treatment with retinoic acid for 8 days. Untreated cells were used for control and were compared to the retinoic acid-treated cells. Differentiation of the cell lines was confirmed by assaying expression of ret mRNA using the reverse-transcriptase polymerase chain reaction (RT-PCR) and gel electrophoresis of the radiolabeled products.
  
  
  RESULTS
  No statistical difference in telomerase activity was noted between control and treated groups.
  
  
  CONCLUSIONS
  While telomerase activity has been shown by others to correlate with tumor aggressiveness in human neuroblastoma cells, the mechanism that is involved appears to be separate from cellular differentiation.
authors.affiliation: Departments of Surgery and Clinical Investigation, Madigan Army Medical Center, Tacoma, Washington 98431, USA. christopher.sanborn@nw.amedd.army.mil
authors.forename: C K
authors.initials: CK
authors.lastname: Sanborn
authors.forename: A
authors.initials: A
authors.lastname: O'Connor
authors.forename: R S
authors.initials: RS
authors.lastname: Sawin
authors.forename: K
authors.initials: K
authors.lastname: Moore
authors.forename: M J
authors.initials: MJ
authors.lastname: Dehart
authors.forename: K S
authors.initials: KS
authors.lastname: Azarow
mesh_terms: D002454:Cell Differentiation / Q000502:physiology; D029721:Drosophila Proteins; D006801:Humans; D009447:Neuroblastoma / Q000201:enzymology* / Q000473:pathology*; D011518:Proto-Oncogene Proteins / Q000235:genetics; D051096:Proto-Oncogene Proteins c-ret; D012333:RNA, Messenger / Q000378:metabolism; D020794:Receptor Protein-Tyrosine Kinases / Q000235:genetics; D012016:Reference Values; D019098:Telomerase / Q000378:metabolism*; D014212:Tretinoin / Q000494:pharmacology; D014407:Tumor Cells, Cultured
chemical_list: D029721:Drosophila Proteins; D011518:Proto-Oncogene Proteins; D012333:RNA, Messenger; D014212:Tretinoin; D051096:Proto-Oncogene Proteins c-ret; D020794:Receptor Protein-Tyrosine Kinases; C416649:Ret protein, Drosophila; D019098:Telomerase