Demethylation of the human telomerase catalytic subunit (hTERT) gene promoter reduced hTERT expression and telomerase activity and shortened telomeres

Details

Serval ID
serval:BIB_D5EAA60ACA05
Type
Article: article from journal or magazin.
Collection
Publications
Institution
Title
Demethylation of the human telomerase catalytic subunit (hTERT) gene promoter reduced hTERT expression and telomerase activity and shortened telomeres
Journal
Experimental Cell Research
Author(s)
Guilleret  I., Benhattar  J.
ISSN
0014-4827 (Print)
Publication state
Published
Issued date
2003
Volume
289
Number
2
Pages
326-334
Notes
PT - Journal Article PT - Research Support, Non-U.S. Gov't
Abstract
Telomerase is the ribonucleoproteic complex involved in maintaining telomere size. It is expressed in germ and stem cells but not in normal somatic cells. In most tumors, telomerase is reactivated. In humans, telomerase activity is tightly regulated by expression of the hTERT gene. In a previous study, we found a direct correlation between methylation of the hTERT promoter and hTERT gene expression. In order to demonstrate this correlation, demethylation experiments were performed with the demethylating agent 5aza-2'-deoxycytidine (5azadC). Three telomerase-positive tumor cell lines (Lan-1, HeLa, and Co115), presenting a hypermethylated hTERT promoter, were treated with different doses and types of treatment for a long period. Analysis of methylation revealed a final hTERT promoter demethylation up to 95%. Quantification of hTERT mRNA showed that transcription was strongly repressed during drug exposure. In contrast, expression of c-Myc, an activator of hTERT promoter, was barely down-regulated or increased by the treatment. Using a TRAP assay, telomerase activity was semiquantified in all experiments. It strongly decreased or was suppressed after two to four passages. Finally, telomere length was measured by Southern blot. Their averages were not modified, but ranges concentrated around the mean. Thus, it is likely that hTERT promoter hypermethylation would be necessary for its expression
Keywords
Antimetabolites,Antineoplastic/pharmacology/Azacitidine/analogs & derivatives/Cell Aging/drug effects/genetics/Cell Division/DNA Methylation/DNA-Binding Proteins/Down-Regulation/Gene Expression Regulation,Neoplastic/Humans/Neoplasms/enzymology/Promoter Regions (Genetics)/Proto-Oncogene Proteins c-myc/metabolism/RNA,Messenger/Telomerase/Telomere/Transcription,Genetic/Tumor Cells,Cultured
Pubmed
Web of science
Create date
29/01/2008 18:36
Last modification date
20/08/2019 15:55
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