title: [Effect of antisense epidermal growth factor receptor cDNA transfection on telomerase activity of glioblastomas cells].
abstract: OBJECTIVE
  To study the effects of antisense epidermal growth factor receptor (EGFR) cDNA transfection on telomerase activity and telomere length of glioblastomas U87MG cells and the mechanism.
  
  
  METHODS
  Glioblastoma U87MG cells, which over-expressed EGFR, were transfected with antisense-EGFR cDNA constructs. Several clones stably expressing lower or undetectable levels of EGFR protein were obtained. The effect of antisense-EGFR cDNA on telomerase activity was assessed by Telomeric Repeat Amplification Protocol (TRAP) assay. The effect of antisense-EGFR cDNA on telomere length was determined by Southern blot hybridization. The mRNA expressions of hTERT, hTEP1 and c-myc were analyzed by semi-quantitative PCR.
  
  
  RESULTS
  U87MG cells that were transfected with antisense-EGFR cDNA expressed lower level of EGFR and were less responsive to the growth stimulation of EGF compared with the control cells. Telomerase activity was significantly decreased in the antisense-EGFR clones. Telomere length was shortened. The mRNA expression of hTERT was slightly decreased in the antisense-EGFR clones, whereas the expressions of hTEP1 and c-myc were not altered.
  
  
  CONCLUSIONS
  Antisense-EGFR cDNA transfection can sufficiently inhibit EGFR signal transduction pathway, decrease telomerase activity and shorten telomere length, which may be a new mechanism of antisense-EGFR approach in tumor suppression. The down-regulation of hTERT mRNA may contribute to the decreased telomerase activity in the antisense-EGFR clones.
authors.affiliation: Department of Pathology, Peking University School of Basic Medical Sciences, Beijing 100083, China. tianxinxia@yahoo.com
authors.forename: Xin-xia
authors.initials: XX
authors.lastname: Tian
authors.forename: Yun-gang
authors.initials: YG
authors.lastname: Zhang
authors.forename: Juan
authors.initials: J
authors.lastname: Du
authors.forename: Jie
authors.initials: J
authors.lastname: Zheng
mesh_terms: D003001:Cloning, Molecular; D016373:DNA, Antisense / Q000235:genetics*; D018076:DNA, Complementary / Q000235:genetics; D066246:ErbB Receptors / Q000235:genetics*; D005909:Glioblastoma / Q000201:enzymology*; D006801:Humans; D019098:Telomerase / Q000378:metabolism*; D014162:Transfection; D014407:Tumor Cells, Cultured
chemical_list: D016373:DNA, Antisense; D018076:DNA, Complementary; D066246:ErbB Receptors; D019098:Telomerase