Dietary Methyl Donor Deficiency Research Articles

Methyl Donor Deficiency Blocks Colorectal Cancer Development by Affecting Key Metabolic Pathways.

Our understanding of the role of folate one-carbon metabolism in colon carcinogenesis remains incomplete. Previous studies indicate that a methyl donor-deficient (MDD) diet lacking folic acid, choline, methionine, and vitamin B12 is associated with long-lasting changes to the intestinal epithelium and sustained tumor protection in Apc-mutant mice. However, the metabolic pathways by which the MDD diet affects these changes are unknown. Colon samples harvested from ApcΔ14/+ mice fed the MDD diet for 18 weeks were profiled using a GC-MS and LC-MS/MS metabolomics platform. Random forest and pathway analyses were used to identify altered metabolic pathways, and associated gene expression changes were analyzed by RT-PCR. Approximately 100 metabolites affected by the MDD diet were identified. As expected, metabolites within the methionine cycle, including methionine (-2.9-fold, P < 0.001) and betaine (-3.3-fold, P < 0.001), were reduced. Elevated homocysteine (110-fold, P < 0.001) was associated with increased flux through the transsulfuration pathway. Unexpectedly, levels of deoxycholic acid (-4.5-fold, P < 0.05) and several other secondary bile acids were reduced. There were also unexpected reductions in the levels of carnitine (-2.0-fold, P < 0.01) and a panel of acylcarnitines involved in fatty acid β-oxidation. Finally, metabolites involved in redox balance, including ascorbate and hypotaurine, were found to be persistently elevated. These findings provide clues to the molecular changes underlying MDD-mediated tumor protection and identify regulatable metabolic pathways that may provide new targets for colon cancer prevention and treatment. IMPLICATIONS: Metabolomic profiling reveals molecular changes underlying MDD-induced tumor protection and may provide new targets for colorectal cancer prevention and treatment.

Paternal methyl donor deficient diets during development affect male offspring behavior and memory-related gene expression in mice.

It has become increasingly evident that the methylation of DNA, known as an epigenetic marker, affects behavior in animals. In our previous study, a methyl-donors (folate, methionine, and choline)-deficient (FMCD) diet during the juvenile period could be shown to affect anxiety-like behavior and fear memory, accompanied by alteration in some gene expression and their methylations in the hippocampus. One question is whether the fear memory of a parent affects the fear responses of offspring. To explore this question in the present study, C57BL/6J male (F0) mice were given a FMCD diet from 3 to 12weeks of age. After confirming the effect of the FMCD diet on the behavior and gene expression of F0 mice, their male offspring (F1-FMCD mice) were examined using the same behavioral batteries and genetic analysis. F0 diet-based differences in F1 behavior were observed, accompanied by the differences in the expression of memory-related genes (Camk2α and PP1) and promoter methylation of the PP1 gene in the hippocampus. Our results add evidence that behavior and gene expression of the F1 generation could be altered due to differences in the father's intake of methyl-donor nutrients.

Effect of maternal methyl donor deficient diet on experimental colitis in rat offsprings

Effect of maternal methyl donor deficient diet on experimental colitis in rat offsprings

Referee Report: Methyl donor deficient diets cause distinct alterations in lipid metabolism but are poorly representative of human NAFLD. Wellcome Open Res 2017, 2:67

Background: Non-alcoholic fatty liver disease (NAFLD) is a global health issue. Dietary methyl donor restriction is used to induce a NAFLD/non-alcoholic steatohepatitis (NASH) phenotype in rodents, however the extent to which this model reflects human NAFLD remains incompletely understood. To address this, we undertook hepatic transcriptional profiling of methyl donor restricted rodents and compared these to published human NAFLD datasets. Methods: Adult C57BL/6J mice were maintained on control, choline deficient (CDD) or methionine/choline deficient (MCDD) diets for four weeks; the effects on methyl donor and lipid biology were investigated by bioinformatic analysis of hepatic gene expression profiles followed by a cross-species comparison with human expression data of all stages of NAFLD. Results: Compared to controls, expression of the very low density lipoprotein (VLDL) packaging carboxylesterases ( Ces1d, Ces1f, Ces3b) and the NAFLD risk allele Pnpla3 were suppressed in MCDD; with Pnpla3 and the liver predominant Ces isoform, Ces3b, also suppressed in CDD. With respect to 1-carbon metabolism, down-regulation of Chka, Chkb, Pcty1a, Gnmt and Ahcy with concurrent upregulation of Mat2a suggests a drive to maintain S-adenosylmethionine levels. There was minimal similarity between global gene expression patterns in either dietary intervention and any stage of human NAFLD, however some common transcriptomic changes in inflammatory, fibrotic and proliferative mediators were identified in MCDD, NASH and HCC. Conclusions: This study suggests suppression of VLDL assembly machinery may contribute to hepatic lipid accumulation in these models, but that CDD and MCDD rodent diets are minimally representative of human NAFLD at the transcriptional level.

Methyl donor deficient diets cause distinct alterations in lipid metabolism but are poorly representative of human NAFLD.

Background: Non-alcoholic fatty liver disease (NAFLD) is a global health issue. Dietary methyl donor restriction is used to induce a NAFLD/non-alcoholic steatohepatitis (NASH) phenotype in rodents, however the extent to which this model reflects human NAFLD remains incompletely understood. To address this, we undertook hepatic transcriptional profiling of methyl donor restricted rodents and compared these to published human NAFLD datasets. Methods: Adult C57BL/6J mice were maintained on control, choline deficient (CDD) or methionine/choline deficient (MCDD) diets for four weeks; the effects on methyl donor and lipid biology were investigated by bioinformatic analysis of hepatic gene expression profiles followed by a cross-species comparison with human expression data of all stages of NAFLD. Results: Compared to controls, expression of the very low density lipoprotein (VLDL) packaging carboxylesterases ( Ces1d, Ces1f, Ces3b) and the NAFLD risk allele Pnpla3 were suppressed in MCDD; with Pnpla3 and the liver predominant Ces isoform, Ces3b, also suppressed in CDD. With respect to 1-carbon metabolism, down-regulation of Chka, Chkb, Pcty1a, Gnmt and Ahcy with concurrent upregulation of Mat2a suggests a drive to maintain S-adenosylmethionine levels. There was minimal similarity between global gene expression patterns in either dietary intervention and any stage of human NAFLD, however some common transcriptomic changes in inflammatory, fibrotic and proliferative mediators were identified in MCDD, NASH and HCC. Conclusions: This study suggests suppression of VLDL assembly machinery may contribute to hepatic lipid accumulation in these models, but that CDD and MCDD rodent diets are minimally representative of human NAFLD at the transcriptional level.

Dietary Methyl Donor Depletion Suppresses Intestinal Adenoma Development.

The role of folate one-carbon metabolism in colorectal cancer development is controversial, with nutritional intervention studies producing conflicting results. It has been reported that ApcMin/+ mice maintained on a diet deficient in the methyl donors folic acid, methionine, choline, and vitamin B12, and supplemented with homocysteine, show a greater than 95% reduction in intestinal tumor development. The present study extends these findings and shows that tumor protection afforded by dietary methyl donor deficiency (MDD) is long-lasting. After 11 weeks of MDD, tumor protection persisted for at least an additional 7 weeks of methyl donor repletion (22.2 ± 3.5 vs. 70.2 ± 4.6 tumors per mouse; P < 0.01). Sustained tumor protection was associated with a reduction in intestinal crypt length (26%, P < 0.01), crypt cell division and crypt fission, and an increase in apoptosis of both normal crypts and tumors (4.9- and 3.2-fold, respectively, P < 0.01). MDD also caused a significant reduction in the number of Dclk1-positive cells in the intestine (62%, P < 0.01), a long-lived crypt cell with cancer stem cell potential. Several undesirable effects associated with methyl donor restriction (e.g., reduced body weight gain) were shown to be transient and readily reversible following methyl donor repletion. Taken together, these results indicate that even temporary dietary methyl donor restriction in adenoma-prone mice can induce persistent changes to the intestinal epithelium and provide long-lasting tumor protection. These data also suggest that transient reductions in dietary methyl donor consumption should be considered when studying the impact of folate on colon cancer risk in humans. Cancer Prev Res; 9(10); 812-20. ©2016 AACR.

Abstract 899: Cancer protection associated with dietary methyl donor deficiency is characterized by persistent changes to epithelial proliferation and metabolism

Abstract The role of folate one-carbon metabolism in colorectal cancer development is incompletely understood, and nutritional intervention studies have produced conflicting results. We previously demonstrated that a diet deficient in the methyl donors folic acid, methionine, choline and vitamin B12, and supplemented with homocysteine, reduces intestinal tumor incidence by greater than 95% in ApcMin/+ mice. Here we extend these findings to a second mouse tumor model, ApcÄ14, and further show that the cancer protection afforded by even short-term dietary methyl donor deficiency (MDD) is long-lasting. Eleven weeks of MDD followed by methyl donor repletion was sufficient to maintain tumor suppression for at least 7 additional weeks (22.2 ± 3.5 vs 70.2 ± 4.6 intestinal tumors; p &amp;lt; 0.001). Sustained tumor protection was associated with altered intestinal crypt homeostasis. MDD increased the proportion of intestinal epithelial cells undergoing apoptosis in normal crypts and in tumors (4.9- and 3.2-fold, respectively), while reducing cell proliferation (Ki-67) and mitosis (PHH3). In addition, metabolomic profiling and metabolite set enrichment analysis (MSEA) revealed that tumor protection is associated with persistent alterations to metabolic pathways related to cellular proliferation, including glutamine metabolism, biogenic amine synthesis, nucleotide salvage and glutathione synthesis. Taken together, these results indicate that even a temporary dietary methyl donor restriction in cancer-prone mice can induce persistent changes to the intestinal epithelium that provide long-lasting protection in adult mice. Citation Format: Matthew P. Hanley, Daniel W. Rosenberg. Cancer protection associated with dietary methyl donor deficiency is characterized by persistent changes to epithelial proliferation and metabolism. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 899.

Abstract 893: Metabolomic profiling of APCΔ14/+ mice maintained on a methyl donor deficient diet reveals alterations to methionine and fatty acid metabolism associated with cancer protection

Abstract Our laboratory has previously demonstrated that administration of a diet deficient in methyl donor nutrients (folic acid, methionine, choline and vitamin B12) reduces tumor multiplicity by greater than 95% in ApcMin/+ mice. However, the mechanism by which this dramatic cancer protection is afforded is unknown. To begin to identify the metabolic consequences of methyl donor deficiency, we have conducted an LC/MS-based metabolic profiling analysis of colonic mucosa collected from ApcΔ14/+ mice fed a methyl donor deficient (MDD) diet for 17 weeks. Methyl donor deficiency causes significant alterations to a number of key metabolic pathways, including those involved in the methionine cycle, fatty acid oxidation, and tryptophan catabolism. We observed significant reductions in methionine (65% reduction, p&amp;lt;0.001) and betaine (70% reduction, p&amp;lt;0.001), accompanied by large increases in homocysteine (88.6-fold increase, p&amp;lt;0.001) and S-adenosylmethionine (17.2-fold increase, p&amp;lt;0.001), confirming that dietary methyl donor deficiency alters one-carbon metabolites in the colon. MDD mice were found to have reduced levels of acyl-carnitines and free carnitine (58% reduction, p&amp;lt;0.001). Additionally, we detected a reduction in the critical metabolic component, acetyl CoA, suggesting decreased transport of fatty acids into the mitochondria for use in fatty acid oxidation (FAO). Finally, we observed changes in the mucosal levels of tryptophan (32% reduction, p = 0.02), kynurenine (2.8-fold increase, p = 0.008) and indolepropionate (5.1-fold increase, p = 0.005), that were retained for seven weeks beyond active methyl donor deficiency. Taken together, these findings suggest that dietary methyl donor deficiency significantly disrupts the methionine cycle, inhibits fatty acid transport and oxidation, and may induce long-term changes to tryptophan metabolism. This study has improved our understanding of the molecular mechanisms underlying the cancer protection conveyed by dietary methyl donor deficiency and has identified metabolic pathways that are candidate targets for chemopreventive intervention. Citation Format: Matthew P. Hanley, Daniel W. Rosenberg. Metabolomic profiling of APCΔ14/+ mice maintained on a methyl donor deficient diet reveals alterations to methionine and fatty acid metabolism associated with cancer protection. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 893. doi:10.1158/1538-7445.AM2015-893

255 High Unsaturated Fat Diets and Unsaturated Visceral Fat Worsen Acute Pancreatitis (AP) Outcomes At Lower Body Mass Index (BMI)

Background & Aims: Environmental enteropathy (EE) is a subclinical intestinal condition highly prevalent in lowand middle-income countries characterized, in part, by malabsorption, intestinal villous atrophy, and crypt hypertrophy. The pathogenesis of EE remains unclear, however supplementation with folate (a key source of one carbon units for DNA methylation) is an effective adjunct therapy for tropical sprue, i.e., persistent diarrhea on a background of EE. To determine the extent to which methyl donor deficiency (MDD) provokes features of EE in mice, we evaluated mechanistic links between dietary methyl donor deficiency and intestinal crypt hypertrophy in mice and in mouse small intestinal crypt cultures (enteroids). Methods: We randomized dams to a standard diet or an isocaloric MDD diet lacking folate, choline, and betaine when pups were 10-days-old. We then randomized weanlings to their dams' diet on day of life 21. Mice were sacrificed and the jejunum was harvested at 6 weeks of age for both histology (n=6/group) and generation of enteroids. Results: Histological comparisons of the jejunum revealed longer crypts in MDD versus control mice, moreso in the distal (85.6 +/13.7 μm vs. 69.3 +/7.2 μm; P<0.0001), vs. proximal (88.8 +/17 μm vs 80.7 +/10.7 μm; P=0.04) portions of the small intestine. Enteroids from control and MDD mice were both viable in standard minigut media; however, all enteroids maintained in MDD media displayed alterations in crypt morphology and decreased epithelial proliferation. Enteroid crypt neck width was 1.3-fold greater in standard vs. MDD media (P<0.001). The number of crypt buds per enteroid was 1.6-fold higher in standard media vs. MDD media (p = 0.0007). The ratio of EdU-positive, or proliferating, cells to Hoechst-positive cells was 2.2-fold higher in standard media vs. MDD media (P<0.0001). Qualitatively, enteroids in MDD media displayed longer crypt domains vs. enteroids in standard media. Conclusions: Complementary in vivo and in vitro findings of altered small intestinal crypt in the setting of methyl donor deficiency suggest that methyl donor deficiency plays a role in the pathogenesis of environmental enteropathy. Further studies are needed to determine whether prolonged methyl donor deficiency promotes epigenetic changes of intestinal stem cells and whether methyl donor supplementation prevents or reverses these changes to promote intestinal epithelial homeostasis in global settings of poverty.

The effects of methyl-donor deficiency on the pattern of gene expression in mice.

Hepatocellular carcinoma is one of the most frequently occurring cancers in humans. Recent human and animal studies have provided strong evidence for the effects of dietary deficiency of methyl donors on the development of liver cancer. However, the mechanisms underlying the effects of methyl-group deficiency on cancer risk are not properly understood. Male BALB/c and CBA/Ca mice were maintained for 8 weeks on a synthetic diet lacking in choline and folic acid. Using microarrays, the pattern of gene expression was evaluated in their liver, kidney, and spleen. Methyl-donor deficient diet induced profound changes in gene expression in the liver of treated animals, whereas the effects of the methyl-deficient diet on the pattern of gene expression in the kidney and spleen were negligible. Methyl-donor dietary restriction induced strain-independent upregulation of genes involved in cellular proliferation in liver. The results of our study provide a plausible explanation of why diets lacking methyl donors can induce the development of liver cancers in rodents and humans.

Methyl donor-deficient diet during development can affect fear and anxiety in adulthood in C57BL/6J mice.

DNA methylation is one of the essential factors in the control of gene expression. Folic acid, methionine and choline (methyl donors)–all nutrients related to one-carbon metabolism–are known as important mediators of DNA methylation. A previous study has shown that long-term administration of a diet lacking in methyl donors caused global DNA hypermethylation in the brain (Pogribny et al., 2008). However, no study has investigated the effects of a diet lacking in methyl donors during the developmental period on emotional behaviors such as fear and anxiety-like behavior in association with gene expressions in the brain. In addition, it has not been elucidated whether a diet supplemented with methyl donors later in life can reverse these changes. Therefore, we examined the effects of methyl donor deficiency during the developmental period on fear memory acquisition/extinction and anxiety-like behavior, and the relevant gene expressions in the hippocampus in juvenile (6-wk) and adult (12-wk) mice. We found that juvenile mice fed a methyl-donor-deficient diet had impaired fear memory acquisition along with decreases in the gene expressions of Dnmt3a and Dnmt3b. In addition, reduced anxiety-like behavior with decreased gene expressions of Grin2b and Gabar2 was observed in both the methyl-donor-deficient group and the body-weight-matched food-restriction group. After being fed a diet supplemented with methyl donors ad libitum, adult mice reversed the alteration of gene expression of Dnmt3a, Dnmt3b, Grin2b and Gabar2, but anxiety-like behavior became elevated. In addition, impaired fear-memory formation was observed in the adult mice fed the methyl-donor-deficient diet during the developmental period. Our study suggested that developmental alterations in the one-carbon metabolic pathway in the brain could have effects on emotional behavior and memory formation that last into adulthood.

OP019 Hypoxia responsive elements methylation status governs adherent-invasive Escherichia coli -receptor CEACAM6 expression in Crohn's disease

OP019 Hypoxia responsive elements methylation status governs adherent-invasive Escherichia coli -receptor CEACAM6 expression in Crohn's disease

Behavioral and neurochemical effects of dietary methyl donor deficiency combined with unpredictable chronic mild stress in rats

Methyl donor deficiencies and chronic stress cause depression independently, but their interaction has never been thoroughly evaluated. In our study, methyl donor deficient diet and chronic stress condition consisted respectively of a B2, B9, B12, and choline-free diet and a chronic mild stress procedure. Rats were randomly assigned to six groups with three “diet” conditions (free-feeding, pair-fed and methyl donor deficient diet) and two “stress” conditions (no-stress and stress) and were evaluated in the open-field, the elevated plus-maze and the forced swimming test. After the behavioral evaluation, corticosterone and homocysteine plasma levels were measured and dopamine, DOPAC, serotonin, 5HIAA concentrations were evaluated in several brain areas. Rats given a methyl donor deficient diet for 11 weeks causing elevated plasma homocysteine levels were compared to pair-fed and free-feeding rats with or without unpredictable chronic mild stress. Regardless of stress environmental conditions, the methyl donor deficient diet decreased plasma corticosterone levels and caused disinhibition in the elevated plus-maze condition relative to both control groups. However, stress potentiated the effects of the deficient regimen on rearing in the open-field and climbing in the forced swim test. The dietary changes involved in behavior and plasma corticosterone could be caused by homocysteine-induced decreases in dopamine and 5-hydroxytryptamine metabolites in selective brain regions and it can be noted that regardless of stress-conditions, methyl donor deficient diet decreases DOPAC/dopamine and 5HIAA/serotonin ratios in striatum and hypothalamus and selectively 5HIAA/serotonin ratio in the sensorimotor cortex. Our experimental data is particularly relevant in the context of neuropsychiatric disorders frequently associated with folate deficiency and hyperhomocysteinemia.

A Steep Learning Curve: Decoding Epigenetic Influence on Behavior and Mental Health

Research on epigenetics has surged in the past two decades as it has become apparent that changes in gene function aside from those related to DNA mutations or natural variations may be integral factors in numerous perplexing health disorders. But much remains unknown about this relatively new field. Of the thousands of epigenetics studies published,1 a few hundred have addressed behavioral and mental health outcomes, but only a fraction of those have dealt with fetal or childhood exposures or outcomes. However, early results in the niche field of behavioral epigenetics suggest such studies could provide insights into behavioral and mental health conditions such as autism spectrum disorders (ASDs), attention deficit/hyperactivity disorder, schizophrenia, bipolar disorder, depression, and anxiety.

Dietary Methyl Donor Depletion Protects Against Intestinal Tumorigenesis in Apc Min/+ Mice

Despite recent population data, the influence of dietary folate supplementation on colon cancer risk remains controversial. This study examines the effects of folate deficiency, in combination with choline, methionine, and vitamin B12 depletion, on intestinal tumorigenesis in Apc(Min/+) mice. Methyl donor sufficient (MDS) and deficient (MDD) diets were started at five or 10 weeks of age and tumors evaluated at 16 weeks. MDD suppressed intestinal tumor formation in Apc(Min/+) mice (~80%) when started at five weeks of age. The protective effect was lost when MDD was initiated at 10 weeks of age, indicating an important time dependency on cancer suppression. Concomitant with cancer protection, MDD restricted body weight gain. Therefore, a second study was conducted in which MDS was given ad libitum or pair-fed with MDD. Although small intestinal tumors were reduced 54% in pair-fed MDS mice, MDD caused a further reduction (96%). In colon, although MDD did not affect tumor numbers, tumor size was reduced. Gene expression profiling of normal-appearing colonic mucosa after 11 weeks on MDD identified a total of 493 significantly downregulated genes relative to the MDS group. Pathway analysis placed many of these genes within general categories of inflammatory signaling and cell-cycle regulation, consistent with recently published human data obtained during folate depletion. Further studies are warranted to investigate the complex interplay of methyl donor status and cancer protection in high-risk populations.

The effects of methyl-donor deficiency on mutation induction and transgenerational instability in mice

The results of recent human and animal studies have provided strong evidence for the epigenetic effects of a dietary deficiency of methyl donors such as folate, choline and methionine on cancer risk and some other common diseases. However, the mechanisms underlying the links between epigenetic alterations and disease remain elusive. To establish whether a methyl-donor deficient diet can result in long-term changes in mutation rate in treated animals and their offspring, BALB/c male mice were maintained for 8 weeks, from 4 weeks of age, on a synthetic diet lacking in choline and folic acid. Using single-molecule PCR, the frequency of mutation at the mouse expanded simple tandem repeat (ESTR) locus Ms6-hm was established in sperm samples of treated males, as well as in sperm and brain of their first-generation offspring. ESTR mutation frequency in the germline of males sacrificed immediately after treatment or sampled 6 and 10 weeks after the end of dietary restriction did not significantly differ from that in age-matched control groups. The frequency of ESTR mutation in DNA samples extracted from sperm and brain of the first-generation offspring of treated mice was also similar to that in controls. The results of our study suggest that the effects of a methyl-donor deficient diet on mutation induction and transgenerational instability in mice are likely to be negligible.

Methyl donor deficiency impairs fatty acid oxidation through PGC-1α hypomethylation and decreased ER-α, ERR-α, and HNF-4α in the rat liver

Folate and cobalamin are methyl donors needed for the synthesis of methionine, which is the precursor of S-adenosylmethionine, the substrate of methylation in epigenetic, and epigenomic pathways. Methyl donor deficiency produces liver steatosis and predisposes to metabolic syndrome. Whether impaired fatty acid oxidation contributes to this steatosis remains unknown. We evaluated the consequences of methyl donor deficient diet in liver of pups from dams subjected to deficiency during gestation and lactation. The deprived rats had microvesicular steatosis, with increased triglycerides, decreased methionine synthase activity, S-adenosylmethionine, and S-adenosylmethionine/S-adenosylhomocysteine ratio. We observed no change in apoptosis markers, oxidant and reticulum stresses, and carnityl-palmitoyl transferase 1 activity, and a decreased expression of SREBP-1c. Impaired beta-oxidation of fatty acids and carnitine deficit were the predominant changes, with decreased free and total carnitines, increased C14:1/C16 acylcarnitine ratio, decrease of oxidation rate of palmitoyl-CoA and palmitoyl-L-carnitine and decrease of expression of novel organic cation transporter 1, acylCoA-dehydrogenase and trifunctional enzyme subunit alpha and decreased activity of complexes I and II. These changes were related to lower protein expression of ER-α, ERR-α and HNF-4α, and hypomethylation of PGC-1α co-activator that reduced its binding with PPAR-α, ERR-α, and HNF-4α. The liver steatosis resulted predominantly from hypomethylation of PGC1-α, decreased binding with its partners and subsequent impaired mitochondrial fatty acid oxidation. This link between methyl donor deficiency and epigenomic deregulations of energy metabolism opens new insights into the pathogenesis of fatty liver disease, in particular, in relation to the fetal programming hypothesis.

Abstract LB-182: Effects of methyl donor status on intestinal tumorigenesis in ApcMin/+ mice

Abstract The goal of the present study is to determine the effects of folate deficiency on intestinal tumorigenesis in ApcMin/+ mice, a widely used animal model for human familial adenomatous polyposis (FAP). Since folate plays an important role in maintaining methyl donor status, dietary folate levels were reduced in combination with a panel of methyl donors, including choline, methionine and vitamin B12. Although the impact of folate on colorectal cancer (CRC) has been studied extensively, its role in cancer chemoprevention remains controversial. For example, folate supplementation has been widely discussed as a strategy for lowering cancer incidence. However, excess folate has also been associated with increased cancer risk. The following studies were designed to evaluate the effects of folate deficiency on intestinal tumorigenesis in ApcMin/+ mice. In Study 1, methyl donor sufficient diet (MDS) and methyl donor deficient diet (MDD) were fed to mice, beginning at either 5 or 10 weeks of age. Intestinal tumors were evaluated at 16 weeks of age. MDD diet suppressed intestinal tumor formation in ApcMin/+ mice by ∼80% when started at 5 weeks of age. Importantly, the protective effect was lost when the MDD diet was started at 10 weeks of age, indicating an important time-dependency on cancer suppression. Gene expression profiling of normal colonic mucosa after 11 weeks on MDD diet identified the most significantly down-regulated genes related to immune response and inflammation, data that are consistent with a recently published human colon expression profiling study (Protiva et al., 2011). The cancer suppression, however, was associated with reduced food intake and lowered body weight gain (up to 40%) throughout the experimental period. To control for this effect, Study 2 was performed in which ApcMin/+ mice were pair-fed with either methyl donor sufficient (MDS) or methyl donor deficient (MDD) diet, beginning at 5 weeks of age for a total of 11 weeks. A third group received MDS ad libitum. At 16 weeks of age, intestinal tumor formation was significantly reduced (54%, p&amp;lt;0.001) in the caloric-restricted MDS group. In the MDD group, however, tumor suppression was almost complete (∼96%, p&amp;lt;0.001). Associated with tumor protection were increased numbers of apoptotic cells within the villous epithelium of the small intestine, with a concomitant reduction in cell proliferation assessed by Ki-67 and Phospho-histone H3 (pHH3). While cancer protection by methyl donor deficiency is partially dependent on reduced caloric intake, additional mechanisms dependent on altered cell turnover must be invoked to explain these results. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr LB-182. doi:1538-7445.AM2012-LB-182

Dietary methyl donor deficiency during pregnancy in rats shapes learning and anxiety in offspring

Two important lines of research have enhanced our understanding of the molecular role of nutrition in influencing behavior. First, exposure to an adverse environment during early life can influence the long-term behavior of the offspring. Second, regulation of the nervous system development and functioning appears to involve epigenetic mechanisms that require a continuous supply of methyl group donors in food. We hypothesized that a maternal diet during pregnancy deficient in methyl donors (MDD) may lead to altered behavior in offspring through permanent changes in hippocampal DNA methylation. We used a rat model of prenatal dietary MDD to test this hypothesis in female offspring as they aged. Prenatal MDD reduced birth weight, litter size, and newborn viability. Aged female offspring of MDD mothers showed increased anxiety and increased learning ability in comparison with control diet group offspring. To explore the role of MDD on epigenetic mechanisms in the brain of adult offspring, we studied expression and methylation of 4 selected genes coding for glucocorticoid receptor, hydroxysteroid dehydrogenase 11 type 2, neuronatin, and reelin proteins in the hippocampus. No major group differences in methylation or expression of the studied genes were detected, except for a significant down-regulation of the reelin gene in the MDD female offspring. The prenatal MDD diet caused intrauterine growth restriction, associated with long-term effects on the behavior of the offspring. However, the observed behavioral differences between the MDD and control diet offspring cannot be explained by epigenetic regulation of the specific genes investigated in this study.

Methyl donor deficient diet during the developmental period changes gene expressions patterns of NMDA receptor subtypes in adults

Methyl donor deficient diet during the developmental period changes gene expressions patterns of NMDA receptor subtypes in adults