Quantitative PCR analysis for methylation level of genome: clinical implications in cancer.
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Date
2007-08
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Abstract
Background: Cancer cells are frequently characterized by hypomethylation of the genome including repetitive
sequences. This epigenetic process is believed to be associated with several biological causes and consequences
in cancer. Therefore, LINE-1 repetitive sequences demethylation in cancer should result in different clinical
outcomes.
Objective: Recently, we have developed an improved quantitative combined bisulfite restriction analysis PCR
protocol that efficiently evaluates the methylation status of LINE-1s; the method is referred to as PCR
“COBRALINE-1”. This article reviewed what have been learned by applying this technique to study methylation
level of repetitive sequences from several sources of genomic DNA.
Results: We have found that LINE-1 methylation patterns among normal tissues are distinct. Therefore, this
epigenetic event may be continuously altered in adult tissues by the process of cellular differentiation. Moreover,
we confirmed that global hypomethylation is an ongoing process that develops during tumor progression, in
addition to previous evidence of genomic and LINE-1 hypomethylation occurring as an early event in
carcinogenesis. COBRALINE-1 is a highly effective technique for evaluating the genome-wide level of methylation,
in particular from tissue samples with minute amounts of low quality DNA. The technique has been applied to
study samples from micro-dissected archived paraffin-embedded tissues and sera of several types of cancer.
Conclusion: The COBRALINE-1 technique demonstrated its potential to be a tumor marker and a great tool to
explore the biology of global hypomethylation.
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Keywords
Cancer, LINE-1, COBRALINE-1, DNA methylation, genomic hypomethylation, global hypomethylation, LINE-1 demethylation, retrotransposon, tumor marker
Citation
Asian Biomedicine (Research Reviews and News); Vol. 1 No. 2 Aug 2007; 121-128.