J Cancer Prev.  2016 Dec;21(4):264-270. 10.15430/JCP.2016.21.4.264.

Iron Supplementation Reverses the Reduction of Hydroxymethylcytosine in Hepatic DNA Associated With Chronic Alcohol Consumption in Rats

• Tammen SA
• Park JE
• Shin PK
• Friso S
• Chung J
• Choi SW

• KMID: 2367564
• DOI: http://doi.org/10.15430/JCP.2016.21.4.264

Abstract

BACKGROUND
Alcohol is known to affect two epigenetic phenomena, DNA methylation and DNA hydroxymethylation, and iron is a cofactor of ten-eleven translocation (TET) enzymes that catalyze the conversion from methylcytosine to hydroxymethylcytosine. In the present study we aimed to determine the effects of alcohol on DNA hydroxymethylation and further effects of iron on alcohol associated epigenetic changes.
METHODS
Twenty-four male Sprague-Dawley rats were fed either Lieber-DeCarli alcohol diet (36% calories from ethanol) or Lieber-DeCarli control diet along with or without iron supplementation (0.6% carbonyl iron) for 8 weeks. Hepatic non-heme iron concentrations were measured by colorimetric assays. Protein levels of hepatic ferritin and transferrin receptor were determined by Western blotting. Methylcytosine, hydroxymethylcytosine and unmodified cytosine in DNA were simultaneously measured by liquid chromatography/mass spectrometry method.
RESULTS
Iron supplementation significantly increased hepatic non-heme iron contents (P < 0.05) but alcohol alone did not. However, both alcohol and iron significantly increased hepatic ferritin levels and decreased hepatic transferrin receptor levels (P < 0.05). Alcohol reduced hepatic DNA hydroxymethylation (0.21% ± 0.04% vs. 0.33% ± 0.04%, P = 0.01) compared to control, while iron supplementation to alcohol diet did not change DNA hydroxymethylation. There was no significant difference in methylcytosine levels, while unmodified cytosine levels were significantly increased in alcohol-fed groups compared to control (95.61% ± 0.08% vs. 95.26% ± 0.12%, P = 0.03), suggesting that alcohol further increases the conversion from hydroxymethylcytosine to unmodified cytosine.
CONCLUSIONS
Chronic alcohol consumption alters global DNA hydroxymethylation in the liver but iron supplementation reverses the epigenetic effect of alcohol.

Keyword

Alcohols; Iron; DNA hydroxymethylation; DNA methylation; Epigenetics

MeSH Terms

Alcohol Drinking*
Alcohols
Animals
Blotting, Western
Cytosine
Diet
DNA Methylation
DNA*
Epigenomics
Ferritins
Humans
Iron*
Liver
Male
Methods
Rats*
Rats, Sprague-Dawley
Receptors, Transferrin
Spectrum Analysis
Alcohols
Cytosine
DNA
Ferritins
Iron
Receptors, Transferrin