Vitamin and antioxidant rich diet increases MLH1 promoter DNA methylation in DMT2 subjects

Abstract

BackgroundOxidative stress may lead to an increased level of unrepaired cellular DNA damage, which is discussed as one risk for tumor initiation. Mismatch repair (MMR) enzymes act as proofreading complexes that maintain the genomic integrity and MMR-deficient cells show an increased mutation rate. One important gene in the MMR complex is the MutL homolog 1 (MLH1) gene. Since a diet rich in antioxidants has the potential to counteract harmful effects by reactive oxygen species (ROS), we investigated the impact of an antioxidant, folate, and vitamin rich diet on the epigenetic pattern of MLH1. These effects were analyzed in individuals with non-insulin depended diabetes mellitus type 2 (NIDDM2) and impaired fasting glucose (IFG).MethodsIn this post-hoc analysis of a randomized trial we analyzed DNA methylation of MLH1, MSH2, and MGMT at baseline and after 8 weeks of intervention, consisting of 300 g vegetables and 25 ml plant oil rich in polyunsaturated fatty acids per day. DNA methylation was quantified using combined bisulfite restriction enzyme analysis (COBRA) and pyrosequencing. MLH1 and DNMT1 mRNA expression were investigated by qRT-PCR. DNA damage was assessed by COMET assay. Student’s two-tailed paired t test and one-way ANOVA with Scheffé corrected Post hoc test was used to determine significant methylation and expression differences. Two-tailed Pearson test was used to determine correlations between methylation level, gene expression, and DNA strand break amount.ResultsThe intervention resulted in significantly higher CpG methylation in two particular MLH1 promoter regions and the MGMT promoter. DNA strand breaks and methylation levels correlated significantly. The expression of MLH1, DNMT1, and the promoter methylation of MSH2 remained stable. CpG methylation levels and gene expression did not correlate.ConclusionThis vitamin and antioxidant rich diet affected the CpG methylation of MLH1. The higher methylation might be a result of the ROS scavenging antioxidant rich diet, leading to lower activity of DNA demethylating enzymes. Our results suggest the hypothesis of CpG demethylation via DNA repair enzymes under these circumstances. NIDDM2 and IFG patients benefit from this simple dietary intervention involving epigenetic and DNA repair mechanisms.

EGCG Containing Combined Dietary Supplement Affects Telomeres and Epigenetic Regulation

“…However, other pathways like the inhibition of HDACs are also discussed as contributing mechanisms. Switzeny et al observed an increased MLH1 promoter DNA methylation in DMT2 subjects following a vitamin and antioxidant rich diet [77]. We could observe that MLH1 showed a trend towards a higher methylation with increasing age, but methylation levels of MLH1 were only marginally affected by the administration.…”

MGMT-B Gene Promoter Hypermethylation in Patients with Inflammatory Bowel Disease - A Novel Finding

“…Reactive oxygen species which is produced during each inflammation such as Inflammatory bowel disease induced spontaneous deamination of cytosine to uracil and 5-hydroxyuracil leads to a G:C to T:A transition mutation, due to its mispairing with adenosine (Switzeny, et al, 2012). Therefore, DNA integrity and DNA repair enzymes are crucial especially in IBD patients.…”

“…Evidence shows that anti-oxidants are able to increase DNA repair enzyme activities (Waris and Ahsan, 2006;Hegde et al, 2008;Switzeny, et al, 2012). Reactive oxygen species which is produced during each inflammation such as Inflammatory bowel disease induced spontaneous deamination of cytosine to uracil and 5-hydroxyuracil leads to a G:C to T:A transition mutation, due to its mispairing with adenosine (Switzeny, et al, 2012).…”

“…Non-dysplastic mucosa of patients with UC induced colorectal cancers shows Kras but not BRAF mutation, indicating that Kras mutations are an initiating event in UC carcinogenesis (Aust et al, 2005). Several studies were also reported that reduced expression and function of DNA repair enzyme induced by oxidative stress during inflammation disease (Switzeny et al, 2012). DNA Mismatch repair elements and O6-methylguanine-DNA methyltransferase (O6-MGMT) are DNA repair proteins.…”

Epigenetics Territory and Cancer

“…Non-dysplastic UC mucosa of patients with UC cancers show K-ras, but not BRAF mutation, indicating that K-ras mutations are initiating events in UC carcinogenesis (Aust et al 2005) Several studies have also reported that reduced expression and function of DNA repair enzyme induced by oxidative stress during inflammation disease (Switzeny et al 2012). Non-dysplastic UC mucosa of patients with UC cancers show K-ras, but not BRAF mutation, indicating that K-ras mutations are initiating events in UC carcinogenesis (Aust et al 2005) Several studies have also reported that reduced expression and function of DNA repair enzyme induced by oxidative stress during inflammation disease (Switzeny et al 2012).…”