Inhibition of DNA methylation by caffeic acid and chlorogenic acid, two common catechol-containing coffee polyphenols

Abstract

We studied the modulating effects of caffeic acid and chlorogenic acid (two common coffee polyphenols) on the in vitro methylation of synthetic DNA substrates and also on the methylation status of the promoter region of a representative gene in two human cancer cells lines. Under conditions that were suitable for the in vitro enzymatic methylation of DNA and dietary catechols, we found that the presence of caffeic acid or chlorogenic acid inhibited in a concentration-dependent manner the DNA methylation catalyzed by prokaryotic M.SssI DNA methyltransferase (DNMT) and human DNMT1. The IC50 values of caffeic acid and chlorogenic acid were 3.0 and 0.75 microM, respectively, for the inhibition of M.SssI DNMT-mediated DNA methylation, and were 2.3 and 0.9 microM, respectively, for the inhibition of human DNMT1-mediated DNA methylation. The maximal in vitro inhibition of DNA methylation was approximately 80% when the highest concentration (20 microM) of caffeic acid or chlorogenic acid was tested. Kinetic analyses showed that DNA methylation catalyzed by M.SssI DNMT or human DNMT1 followed the Michaelis-Menten curve patterns. The presence of caffeic acid or chlorogenic acid inhibited DNA methylation predominantly through a non-competitive mechanism, and this inhibition was largely due to the increased formation of S-adenosyl-L-homocysteine (SAH, a potent inhibitor of DNA methylation), resulting from the catechol-O-methyltransferase (COMT)-mediated O-methylation of these dietary catechols. Using cultured MCF-7 and MAD-MB-231 human breast cancer cells, we also demonstrated that treatment of these cells with caffeic acid or chlorogenic acid partially inhibited the methylation of the promoter region of the RARbeta gene. The findings of our present study provide a general mechanistic basis for the notion that a variety of dietary catechols can function as inhibitors of DNA methylation through increased formation of SAH during the COMT-mediated O-methylation of these dietary chemicals.

An enzyme-coupled high-throughput assay for screening RNA methyltransferase activity inE. Colicell lysate

“…32 However, in this case the inhibition mechanism was non-competitive, caused simply by accumulation of SAH in the presence of catechol-O-methyltransferase (COMT). Chlorogenic and caffeic acids are substrates of COMT and thus increased SAH level.…”

“…Chlorogenic and caffeic acids are substrates of COMT and thus increased SAH level. 32 Since the effect of chlorogenic and caffeic acid on nucleic acid methyltransferases is indirect, it is plausible that there is no effect on hTGS1 activity. From this proof of principle tests we conclude that the enzyme-coupled assay can be readily implemented for screening of novel TGS inhibitors.…”

Role of Physical Activity in Modulating Breast Cancer Risk as Defined byAPCandRASSF1APromoter Hypermethylation in Nonmalignant Breast Tissue

“…Alternatively, lifestyle changes may reverse promoter methylation of tumor suppressor genes. A recent study found that two common catechol-containing polyphenols, caffeic acid and chlorogenic acid, partially inhibited methylation of the promoter region of the RARb2 gene in cultured MCF-7 and MDA-MB-231 human breast cancer cells (31).…”

Mandatory fortification with folic acid in the United States is associated with increased expression of DNA methyltransferase-1 in the cervix

“…This may result in higher expression of Dnmt. Inhibition of Dnmt via high SAH has been shown to reduce methylation in promoter regions of genes, but not at the level of global DNA methylation (4). Whether the opposite effect may hold true, namely, reduced inhibition of Dnmt because of lower SAH is not reported, but this possibility cannot be excluded.…”