[Effect of antisense epidermal growth factor receptor cDNA transfection on telomerase activity of glioblastomas cells].

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. CONCLUSION: 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.