RESUMO
BACKGROUND: Aberrancies in fetal DNA methylation programming may modify disease susceptibility of the offspring. Maternal folate status has potential to alter fetal DNA methylation. OBJECTIVES: We examined the association of maternal and cord blood concentrations of folate and unmetabolized folic acid (UMFA), vitamin B-12, vitamin B-6, and choline with fetal DNA methylation and hydroxymethylation and assessed potential modifying effects of 38 fetal genetic variants in 22 genes. METHODS: Nutrient blood concentrations were measured in 368 pregnant women in early pregnancy (12-16 wk of gestation) and at delivery (37-42 wk of gestation) and in cord blood. DNA methylation and hydroxymethylation in cord blood mononuclear cells were quantified by LC-MS/MS. Pearson partial correlations were used to determine the association between individual nutrients and DNA methylation and hydroxymethylation. RESULTS: Serum and RBC folate and plasma UMFA concentrations (primary outcomes) in early pregnancy, at delivery, and in cord blood were not significantly associated with fetal DNA methylation. In contrast, maternal RBC folate in early pregnancy (r = -0.16, P = 0.04) and cord plasma UMFA (r = -0.23, P = 0.004) were inversely correlated with fetal DNA hydroxymethylation. Neither maternal and cord blood concentrations of other nutrients nor fetal genotypes (secondary outcomes) were significantly associated with fetal DNA methylation or hydroxymethylation. Infants born to mothers with RBC folate concentrations in the highest quartile and serum vitamin B-12 concentrations in the lowest quartile in early pregnancy had significantly lower fetal DNA methylation and higher birth weight compared with those born to mothers with lower RBC folate and higher serum vitamin B-12 concentrations (P = 0.01). CONCLUSIONS: Maternal and cord blood folate concentrations are associated with fetal DNA hydroxymethylation, but not DNA methylation, in a cohort of pregnant Canadian women. The observation that high folate and low vitamin B-12 maternal status in early pregnancy may be associated with decreased fetal DNA methylation and higher birth weight warrants further investigation. This trial was registered at clinicaltrials.gov as NCT02244684.
Assuntos
Metilação de DNA , DNA/metabolismo , Sangue Fetal/metabolismo , Feto/metabolismo , Ácido Fólico/sangue , Biomarcadores/metabolismo , Canadá , Cromatografia Líquida , Feminino , Humanos , Recém-Nascido , Gravidez , Espectrometria de Massas em TandemRESUMO
Vitamin B6 is important in fetal development, but little is known of the vitamin B6 status of pregnant women and newborns in North America and potential modifying factors. This prospective study determined maternal and cord plasma concentrations of pyridoxal 5' phosphate (PLP; an indicator of vitamin B6 status) in a convenience sample of 368 Canadian pregnant women and their newborns. The association of maternal intake of vitamin B6 and fetal genetic variants with cord plasma PLP and homocysteine concentrations was also examined. Dietary and supplemental intakes of vitamin B6 were assessed in early and mid to late pregnancy. PLP concentrations were measured in maternal plasma in early pregnancy and at delivery, and in cord plasma. Six fetal variants of the MTHFR and CßS genes were assessed for their association with cord plasma PLP and homocysteine concentrations. Geometric mean (95% CI) PLP concentrations were 107 (98, 116) nmol/L in early pregnancy and 58 (53, 62) nmol/L at delivery, respectively, and 296 (275, 319) nmol/L in cord blood (p < .0001). During early pregnancy and at delivery, 3.6% and 5.5% of women had plasma PLP concentrations <20 nmol/L, respectively. Ninety eight percent of the women with supplemental B6 intake of at least the recommended dietary allowance had PLP concentrations >20 nmol/L. Fetal genetic variants were not associated with cord PLP and homocysteine concentrations. Vitamin B6 deficiency is uncommon in a cohort of Canadian pregnant women due largely to prevalent vitamin B6 supplement use.
Assuntos
Dieta Saudável , Suplementos Nutricionais , Fenômenos Fisiológicos da Nutrição Materna , Cooperação do Paciente , Fosfato de Piridoxal/sangue , Saúde da População Urbana , Deficiência de Vitamina B 6/prevenção & controle , Adulto , Estudos de Coortes , Dieta Saudável/etnologia , Feminino , Sangue Fetal/química , Humanos , Fenômenos Fisiológicos da Nutrição do Lactente/etnologia , Recém-Nascido , Masculino , Fenômenos Fisiológicos da Nutrição Materna/etnologia , Inquéritos Nutricionais , Ontário/epidemiologia , Cooperação do Paciente/etnologia , Gravidez , Complicações na Gravidez/sangue , Complicações na Gravidez/epidemiologia , Complicações na Gravidez/etnologia , Complicações na Gravidez/prevenção & controle , Prevalência , Fosfato de Piridoxal/deficiência , Saúde da População Urbana/etnologia , Vitamina B 6/uso terapêutico , Deficiência de Vitamina B 6/sangue , Deficiência de Vitamina B 6/epidemiologia , Deficiência de Vitamina B 6/etnologia , Adulto JovemRESUMO
BACKGROUND: Among Canadian women of reproductive age, 5% and 20% have serum vitamin B-12 concentrations indicative of deficiency (<148 pmol/L) and marginal status (148-220 pmol/L), respectively. Given the association between suboptimal vitamin B-12 and adverse pregnancy outcomes, an understanding of vitamin B-12 status during pregnancy, and factors that influence it, is required. OBJECTIVE: This prospective analysis from the PREFORM (PREnatal FOlic acid exposuRe on DNA Methylation in the newborn infant) study investigated 1) vitamin B-12 status in a cohort of Canadian pregnant women and their newborns, 2) the association of maternal dietary vitamin B-12 intake with maternal and cord blood concentrations of vitamin B-12 and its biomarkers, and 3) the association of fetal genetic polymorphisms with cord blood concentrations of vitamin B-12 and its biomarkers. METHODS: In pregnant Canadian women (n = 368; mean ± SD age: 32 ± 5 y), vitamin B-12 intakes were assessed in early (0-16 wk) and mid- to late (23-37 wk) pregnancy. Serum vitamin B-12 and plasma total homocysteine (tHcy) and methylmalonic acid (MMA) in maternal blood at 12-16 wk of pregnancy and at delivery (28-42 wk) and in cord blood were measured and compared by using regression analyses. The associations of 28 fetal genetic variants in vitamin B-12 metabolism and cord blood vitamin B-12, tHcy, and MMA concentrations were assessed by using regression analysis, with adjustment for multiple testing. RESULTS: A total of 17% and 38% of women had deficient and 35% and 43% had marginal serum vitamin B-12 concentrations at 12-16 wk of pregnancy and at delivery, respectively. Only 1.9-5.3% had elevated MMA (>271 nmol/L), and no women had elevated tHcy (>13 µmol/L). Maternal dietary vitamin B-12 intake during pregnancy was either weakly associated or not associated with maternal and cord blood vitamin B-12 (r(2) = 0.17-0.24, P < 0.0008), tHcy (P = NS) and MMA (r(2) = 0.05-0.11, P < 0.001). Fetal genetic polymorphisms were not associated with cord blood concentrations of vitamin B-12 and its biomarkers. CONCLUSIONS: Deficient and marginal serum vitamin B-12 concentrations are prevalent in Canadian pregnant women with the use of traditional cutoffs, despite supplement use. Given the growing interest among women to adhere to a vegetarian diet that may be lower in vitamin B-12, and vitamin B-12's importance in pregnancy, the functional ramifications of these observations need to be elucidated. This trial was registered at clinicaltrials.gov as NCT02244684.
Assuntos
Complicações na Gravidez/epidemiologia , Deficiência de Vitamina B 12/epidemiologia , Vitamina B 12/sangue , Adulto , Canadá/epidemiologia , Metilação de DNA , Dieta , Suplementos Nutricionais , Feminino , Sangue Fetal/metabolismo , Feto , Ácido Fólico/sangue , Homocisteína/sangue , Humanos , Recém-Nascido , Ácido Metilmalônico/sangue , Polimorfismo Genético , Gravidez , Prevalência , Estudos Prospectivos , Vitamina B 12/administração & dosagem , Complexo Vitamínico B/administração & dosagem , Complexo Vitamínico B/sangueRESUMO
Folic acid (FA) fortification and widespread supplemental use have significantly increased folate status in North America. Furthermore, >50% of colorectal cancer patients use FA supplement. The increased folate status may interfere with cancer chemotherapy. We investigated the effect of FA supplementation on chemosensitivity of human colon cancer cells to 5-fluorouracil (5-FU) using a xenograft model. Mice harboring human HCT116 colon cancer xenografts were randomized to receive the control, or 4× or 12.5× supplemental levels of FA. Within each diet group, mice were randomized to receive 5-FU+leucovorin or saline and xenograft growth and characteristics were determined. The expression of genes involved in folate metabolism and cancer treatment was determined. FA supplementation and 5-FU significantly interacted to influence xenograft growth (P < 0.007). At the control level, 5-FU significantly inhibited the growth of the xenografts (P < 0.0001). However, at the 4× supplemental level, 5-FU-treated xenografts grew faster than untreated xenografts (P = 0.048) while at the 12.5× supplemental level, 5-FU exhibited no effect. Cell proliferation, degree of necrosis, and expression of the selected genes did not significantly differ by the supplemental levels of FA. Our data suggest that FA supplementation may be detrimental to 5-FU chemotherapy of colon cancer and pose public health concern.
Assuntos
Neoplasias do Colo/tratamento farmacológico , Suplementos Nutricionais , Fluoruracila/farmacologia , Ácido Fólico/farmacologia , Animais , Proliferação de Células/efeitos dos fármacos , Neoplasias do Colo/genética , Modelos Animais de Doenças , Interações Medicamentosas , Células Epiteliais/efeitos dos fármacos , Células Epiteliais/metabolismo , Regulação Neoplásica da Expressão Gênica , Células HCT116 , Homocisteína/metabolismo , Humanos , Masculino , Camundongos , Camundongos Nus , Proteínas Associadas à Resistência a Múltiplos Medicamentos/genética , Proteínas Associadas à Resistência a Múltiplos Medicamentos/metabolismo , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
BACKGROUND: Choline deficiency during pregnancy can lead to adverse birth outcomes, including impaired neurodevelopment and birth defects. Genetic variants of choline and one-carbon metabolism may also influence birth outcomes by altering plasma choline concentrations. The effects of maternal ad libitum choline intake during pregnancy and fetal genetic variants on maternal and cord concentrations of choline and its metabolites are unknown. OBJECTIVES: This prospective study sought to assess the effect of 1) maternal dietary choline intake on maternal and cord plasma concentrations of choline and its metabolites, and 2) fetal genetic polymorphisms on cord plasma concentrations. METHODS: The dietary choline intake of 368 pregnant Canadian women was assessed in early (0-16 wk) and late (23-37 wk) pregnancy with the use of a food frequency questionnaire. Plasma concentrations of free choline and its metabolites were measured in maternal samples at recruitment and delivery, and in the cord blood. Ten fetal genetic variants in choline and one-carbon metabolism were assessed for their association with cord plasma concentrations of free choline and its metabolites. RESULTS: Mean maternal plasma free choline, dimethylglycine, and trimethylamine N-oxide (TMAO) concentrations increased during pregnancy by 49%, 17%, and 13%, respectively (P < 0.005), whereas betaine concentrations decreased by 21% (P < 0.005). Cord plasma concentrations of free choline, betaine, dimethylglycine, and TMAO were 3.2, 2.0, 1.3, and 0.88 times corresponding maternal concentrations at delivery, respectively (all P < 0.005). Maternal plasma concentrations of betaine, dimethylglycine, and TMAO (r(2) = 0.19-0.51; P < 0.0001) at delivery were moderately strong, whereas maternal concentrations of free choline were not significant (r(2) = 0.12; P = 0.06), predictors of cord plasma concentrations of these metabolites. Neither maternal dietary intake nor fetal genetic variants predicted maternal or cord plasma concentrations of choline and its metabolites. CONCLUSION: These data collectively indicate that maternal choline status, but not fetal genotype, influences cord plasma concentrations of choline metabolites. This trial was registered at clinicaltrials.gov as NCT02244684.
Assuntos
Colina/sangue , Sangue Fetal/química , Genótipo , Fenômenos Fisiológicos da Nutrição Materna , Adolescente , Adulto , Betaína/sangue , Canadá , Feminino , Feto , Voluntários Saudáveis , Humanos , Metilaminas/sangue , Pessoa de Meia-Idade , Polimorfismo de Nucleotídeo Único , Gravidez , Estudos Prospectivos , Sarcosina/análogos & derivados , Sarcosina/sangue , Inquéritos e Questionários , Adulto JovemRESUMO
BACKGROUND & AIMS: Previous studies have suggested that dietary folic acid (FA) can protect against certain types of cancers. However, the findings have varied, and the mechanisms by which FA exerts chemopreventive effects remain to be clarified. We examined the effects of FA supplementation on DNA methylation, gene expression, and gastric dysplasia in a transgenic mouse model that is etiologically and histologically well matched with human gastric cancers. METHODS: Hypergastrinemic mice infected with Helicobacter felis were studied at multiple stages of gastric dysplasia and early cancer with FA supplementation initiated both at weaning and later in life. Global DNA methylation was assessed by a methylation sensitive cytosine incorporation assay, bisulfite pyrosequencing of B1 repetitive elements, and immunohistochemistry with anti-5-methylcytosine. We also profiled gene expression in the same tissues. RESULTS: We found a decrease in global DNA methylation and tissue folate and an increase in serum homocysteine with progression of gastric dysplasia. FA supplementation prevented this loss of global DNA methylation and markedly reduced gastric dysplasia and mucosal inflammation. FA protected against the loss of global DNA methylation both in the dysplastic gastric epithelial cells and in gastric stromal myofibroblasts. In addition, FA supplementation had an anti-inflammatory effect, as indicated by expression profiling and immunohistochemistry for lymphocyte markers. CONCLUSIONS: We conclude that FA supplementation is chemopreventive in this model of Helicobacter-associated gastric cancer. The beneficial effect of FA is likely due to its ability to prevent global loss of methylation and suppress inflammation.
Assuntos
Anti-Inflamatórios/farmacologia , Anticarcinógenos/farmacologia , Metilação de DNA/efeitos dos fármacos , Ácido Fólico/farmacologia , Gastrite/prevenção & controle , Infecções por Helicobacter/prevenção & controle , Helicobacter felis/patogenicidade , Neoplasias Gástricas/prevenção & controle , Estômago/efeitos dos fármacos , Animais , Modelos Animais de Doenças , Mucosa Gástrica/metabolismo , Gastrinas/genética , Gastrinas/metabolismo , Gastrite/sangue , Gastrite/genética , Gastrite/microbiologia , Gastrite/patologia , Perfilação da Expressão Gênica , Regulação da Expressão Gênica/efeitos dos fármacos , Infecções por Helicobacter/sangue , Infecções por Helicobacter/complicações , Infecções por Helicobacter/genética , Infecções por Helicobacter/microbiologia , Infecções por Helicobacter/patologia , Homocisteína/sangue , Imuno-Histoquímica , Linfócitos/efeitos dos fármacos , Linfócitos/microbiologia , Linfócitos/patologia , Masculino , Camundongos , Camundongos Transgênicos , Miofibroblastos/efeitos dos fármacos , Miofibroblastos/microbiologia , Miofibroblastos/patologia , Estômago/microbiologia , Estômago/patologia , Neoplasias Gástricas/sangue , Neoplasias Gástricas/genética , Neoplasias Gástricas/microbiologia , Neoplasias Gástricas/patologia , Células Estromais/efeitos dos fármacos , Células Estromais/microbiologia , Células Estromais/patologia , Regulação para CimaRESUMO
BACKGROUND: Intrauterine and early life exposure to folic acid has significantly increased in North America owing to folic acid fortification, widespread supplemental use and periconceptional folic acid supplementation. The effect of maternal and postweaning folic acid supplementation on colorectal cancer risk in the offspring was investigated. METHODS: Female rats were placed on a control or supplemental (2.5× the control) diet prior to mating and during pregnancy and lactation. At weaning, male pups from each maternal diet group were randomised to the control or supplemental diet (n=55 per each of the four maternal/pup diet groups) for 31 weeks and colorectal cancer was induced by azoxymethane at 5 weeks of age. At necropsy, colorectal cancer parameters as well as colorectal epithelial proliferation, apoptosis and global DNA methylation were determined in the offspring. RESULTS: Maternal, but not postweaning, folic acid supplementation significantly reduced the odds of colorectal adenocarcinoma by 64% in the offspring (OR 0.36; 95% CI 0.18 to 0.71; p=0.003). Pups from the dams fed the control diet that were given postweaning folic acid supplementation had significantly higher tumour multiplicity and burden than other groups (p<0.05). Maternal and postweaning folic acid supplementation interacted in a manner that decreased rectal epithelial proliferation (p<0.05). Both maternal and postweaning folic acid supplementation significantly decreased DNA damage in the rectum (p<0.05). Maternal folic acid supplementation significantly increased (p=0.007), whereas postweaning supplementation significantly decreased (p<0.001), colorectal global DNA methylation. CONCLUSIONS: The data suggest for the first time that maternal folic acid supplementation at the level equivalent to the average postfortification total folate intake in North America and to that recommended to women at reproductive age protects against the development of colorectal cancer in the offspring. This protective effect may be mediated in part by increased global DNA methylation and decreased epithelial proliferation and DNA damage in the colorectum.
Assuntos
Neoplasias Colorretais/induzido quimicamente , Suplementos Nutricionais , Ácido Fólico/farmacologia , Efeitos Tardios da Exposição Pré-Natal/metabolismo , Animais , Animais Recém-Nascidos , Apoptose/efeitos dos fármacos , Azoximetano/farmacologia , Carcinógenos/farmacologia , Proliferação de Células/efeitos dos fármacos , Neoplasias Colorretais/patologia , Metilação de DNA/efeitos dos fármacos , Feminino , Mucosa Intestinal/efeitos dos fármacos , Mucosa Intestinal/patologia , Masculino , Gravidez , Ratos , Ratos Sprague-Dawley , Fatores de Risco , DesmameRESUMO
Whether or not folic acid supplementation promotes the progression of colorectal preneoplastic lesions to cancer is an important public health issue, given mandatory fortification and widespread supplemental use of folic acid in North America. We investigated the effect of folic acid supplementation on the progression of aberrant crypt foci (ACF), the earliest precursor of colorectal cancer. Male Sprague-Dawley rats (n = 152) were placed on a control diet (2 mg folic acid/kg diet) at weaning and ACF were induced by azoxymethane. Six weeks post-ACF induction, rats were randomized to receive 0, 2, 5 or 8 mg folic acid/kg diet. At 34 weeks of age, rats were killed, and colorectal tumor parameters, plasma folate and homocysteine (a sensitive inverse indicator of tissue folate status) concentrations and rectal epithelial proliferation were determined. Although the number of ACF increased as dietary folic acid levels increased (P = 0.015), the incidence of colorectal tumors did not differ significantly among the four dietary groups. However, tumor multiplicity was positively correlated with dietary folic acid levels (r = 0.32; P = 0.002) and inversely with plasma homocysteine concentrations (r = -0.32; P = 0.005). Tumor burden was positively correlated with dietary folic acid levels (r = 0.35; P = 0.001) and plasma folate concentrations (r = 0.33; P = 0.008) and inversely with plasma homocysteine concentrations (r = -0.42; P < 0.001). Rectal epithelial proliferation was positively correlated with dietary folic acid levels (r = 0.39; P < 0.001) and plasma folate concentrations (r = 0.34; P < 0.001) and inversely with plasma homocysteine concentrations (r = -0.37; P < 0.001). Our data suggest that folic acid supplementation may promote the progression of ACF to colorectal tumors.
Assuntos
Neoplasias Colorretais/etiologia , Ácido Fólico/administração & dosagem , Lesões Pré-Cancerosas/patologia , Animais , Proliferação de Células , Suplementos Nutricionais , Progressão da Doença , Ácido Fólico/sangue , Homocisteína/sangue , Fígado/metabolismo , Masculino , Ratos , Ratos Sprague-DawleyRESUMO
The C677T polymorphism in the methylenetetrahydrofolate reductase (MTHFR) gene is associated with a decreased risk of colon cancer although it may increase the risk of breast cancer. This polymorphism is associated with changes in intracellular folate cofactors, which may affect DNA methylation and synthesis via altered one-carbon transfer reactions. We investigated the effect of this mutation on DNA methylation and uracil misincorporation and its interaction with exogenous folate in further modulating these biomarkers of one-carbon transfer reactions in an in vitro model of the MTHFR 677T mutation in HCT116 colon and MDA-MB-435 breast adenocarcinoma cells. In HCT116 cells, the MTHFR 677T mutation was associated with significantly increased genomic DNA methylation when folate supply was adequate or high; however, in the setting of folate insufficiency, this mutation was associated with significantly decreased genomic DNA methylation. In contrast, in MDA-MB-435 cells, the MTHFR 677T mutation was associated with significantly decreased genomic DNA methylation when folate supply was adequate or high and with no effect when folate supply was low. The MTHFR 677T mutation was associated with a nonsignificant trend toward decreased and increased uracil misincorporation in HCT116 and MDA-MB-435 cells, respectively. Our data demonstrate for the first time a functional consequence of changes in intracellular folate cofactors resulting from the MTHFR 677T mutation in cells derived from the target organs of interest, thus providing a plausible cellular mechanism that may partly explain the site-specific modification of colon and breast cancer risks associated with the MTHFR C677T mutation.
Assuntos
Dano ao DNA/genética , Metilação de DNA , Metilenotetra-Hidrofolato Redutase (NADPH2)/genética , Mutação/genética , Polimorfismo Genético/genética , Uracila/metabolismo , Western Blotting , Neoplasias da Mama/genética , Neoplasias da Mama/metabolismo , Neoplasias da Mama/patologia , Neoplasias do Colo/genética , Neoplasias do Colo/metabolismo , Neoplasias do Colo/patologia , Ilhas de CpG , Ácido Fólico/metabolismo , Regulação Neoplásica da Expressão Gênica , Genótipo , Homocisteína/metabolismo , Humanos , Metionina/metabolismo , Fatores de Risco , Células Tumorais CultivadasRESUMO
Folate plays an important role in the pathogenesis of several chronic diseases by its potential ability to modulate DNA methylation. We hypothesized that the postweaning period might be a highly susceptible period to dietary folate intervention for DNA methylation patterning. We determined the effects of timing and duration of dietary folate intervention provided during the postweaning period on genomic DNA methylation in adult rat liver. In study 1, weanling rats were randomized to receive an amino acid-defined diet containing 0 (deficient), 2 (control), or 8 (supplemented) mg folic acid/kg until 8 wk of age, after which all the rats were fed the control diet until 30 wk of age. In study 2, weanling rats were fed the control diet until 8 wk of age and then randomized to receive the diet containing 0, 2, or 8 mg folic acid/kg until 30 wk of age. In study 3, weanling rats were randomized to receive these diets until 30 wk of age. Dietary folate deficiency, but not supplementation, provided during the postweaning period through childhood to puberty significantly increased genomic DNA methylation by 34-48% (P < 0.04) in rat liver that persisted into adulthood following a return to the control diet at puberty. In contrast, dietary folate deficiency or supplementation continually imposed at weaning or at puberty did not significantly affect genomic DNA methylation in adult rat liver. Our data suggest that early folate nutrition during postnatal development plays an important role in epigenetic programming that can have a permanent effect in adulthood.
Assuntos
Metilação de DNA , Dieta , Deficiência de Ácido Fólico/metabolismo , Ácido Fólico/sangue , Fígado/metabolismo , Envelhecimento , Animais , Feminino , Ácido Fólico/análise , Perfilação da Expressão Gênica , Regulação da Expressão Gênica , Fígado/química , Ratos , Ratos Sprague-Dawley , Maturidade Sexual , DesmameRESUMO
Folylpolyglutamyl synthase (FPGS) converts intracellular folates and antifolates to polyglutamates. Polyglutamylated folates and antifolates are retained in cells longer and are better substrates than their monoglutamate counterparts for enzymes involved in one-carbon transfer. FPGS modulation affects the chemosensitivity of cancer cells to antifolates, such as methotrexate, and 5-fluorouracil (5FU) by altering polyglutamylation of antifolates and specific target intracellular folate cofactors. However, this effect may be counterbalanced by FPGS modulation-induced changes in polyglutamylation of other intracellular folate cofactors and total intracellular folate pools. We generated an in vitro model of FPGS overexpression and inhibition in breast cancer cells by stably transfecting human MDA-MB-435 breast cancer cells with the sense FPGS cDNA or FPGS-targeted small interfering RNA, respectively, and investigated the effects of FPGS modulation on chemosensitivity to 5FU and methotrexate. FPGS modulation-induced changes in polyglutamylation of both antifolates and folate cofactors and in intracellular folate pools affected chemosensitivity of breast cancer cells to pemetrexed and trimetrexate whose cytotoxic effects do or do not depend on polyglutamylation, respectively, in a predictable manner. However, the effects of FPGS modulation on the chemosensitivity of breast cancer cells to 5FU and methotrexate seem to be highly complex and depend not only on polyglutamylation of a specific target intracellular folate cofactor or methotrexate, respectively, but also on total intracellular folate pools and polyglutamylation of other intracellular folate cofactors. Whether or not FPGS modulation may be an important clinical determinant of chemosensitivity of breast cancer cells to 5FU and methotrexate-based chemotherapy needs further exploration.
Assuntos
Neoplasias da Mama/enzimologia , Neoplasias da Mama/patologia , Ensaios de Seleção de Medicamentos Antitumorais , Ácido Fólico/farmacologia , Peptídeo Sintases/metabolismo , Linhagem Celular Tumoral , Glutamatos/farmacologia , Guanina/análogos & derivados , Guanina/farmacologia , Humanos , Concentração Inibidora 50 , Metotrexato/farmacologia , Pemetrexede , Ácido Poliglutâmico/metabolismo , RNA Interferente Pequeno , TransfecçãoRESUMO
Both insufficiency and excess of one-carbon nutrients (folate, choline, vitamins B6 and B12) during pregnancy have been associated with gestational diabetes mellitus (GDM). However, the precise nature of this association has not been clearly established. We hypothesized that GDM may affect one-carbon nutrients concentrations in the fetus, thus possibly participating in epigenetic programing of the offspring. Maternal blood was collected at recruitment (12-16 weeks). At delivery (28-42 weeks), both maternal and cord blood were collected. Blood concentrations of one-carbon nutrients and their metabolites were compared between the two groups. A total of 368 women were included in the study, of whom 19 (5.6%) were later diagnosed with GDM. No significant differences were found in maternal blood concentrations of one-carbon nutrients and their metabolites between the GDM and control groups at recruitment or at delivery. In cord blood, however, serum folate (87.7 [IQR 70.4-103.9] vs 66.6 [IQR 45.5-80.3] nmol/L, P = .025) and plasma TMAO (2.82 [IQR 1.3-3.2] vs 1.35 [IQR 1.0-2.0] µmol/L, P = .017) concentrations were higher, while plasma betaine concentrations were lower (17.5 [IQR 16.3-19.4] vs 21.1 [IQR 18.0-24.1] µmol/L, P = .019) in infants born to mothers with GDM compared with control. Our data suggest that while maternal blood concentrations of one-carbon nutrients and their metabolites may not affect the risk of GDM, GDM may alter concentrations of serum folate, plasma betaine and TMAO in cord blood. These alterations in one-carbon nutrient concentrations in fetal circulation may impact epigenetic programing, thereby contributing to physiologic changes and disease susceptibility in adulthood associated with GDM offspring.
Assuntos
Carbono/metabolismo , Diabetes Gestacional , Sangue Fetal/metabolismo , Feto , Nutrientes/metabolismo , Estado Nutricional , Complexo Vitamínico B/sangue , Adulto , Betaína/sangue , Colina/sangue , Diabetes Gestacional/fisiopatologia , Feminino , Desenvolvimento Fetal , Ácido Fólico/sangue , Humanos , Recém-Nascido , Gravidez , Cuidado Pré-Natal , Vitamina B 12/sangue , Vitamina B 6/sangueRESUMO
Maternal folic acid supplementation can alter DNA methylation and gene expression in the developing fetus, which may confer disease susceptibility later in life. We determined which gestation period and organ were most sensitive to the modifying effect of folic acid supplementation during pregnancy on DNA methylation and gene expression in the offspring. Pregnant rats were randomized to a control diet throughout pregnancy; folic acid supplementation at 2.5× the control during the 1st, 2nd or 3rd week of gestation only; or folic acid supplementation throughout pregnancy. The brain, liver, kidney and colon from newborn pups were analyzed for folate concentrations, global DNA methylation and gene expression of the Igf2, Er-α, Gr, Ppar-α and Ppar-γ genes. Folic acid supplementation during the 2nd or 3rd week gestation or throughout pregnancy significantly increased brain folate concentrations (P<.001), while only folic acid supplementation throughout pregnancy significantly increased liver folate concentrations (P=.005), in newborn pups. Brain global DNA methylation incrementally decreased from early to late gestational folic acid supplementation and was the lowest with folic acid supplementation throughout pregnancy (P=.026). Folic acid supplementation in late gestation or throughout pregnancy significantly decreased Er-α, Gr and Ppar-α gene expression in the liver (P<.05). The kidney and colon were resistant to the effect of folic acid supplementation. Maternal folic acid supplementation affects tissue folate concentrations, DNA methylation and gene expression in the offspring in a gestation-period-dependent and organ-specific manner.
Assuntos
Metilação de DNA , Suplementos Nutricionais , Desenvolvimento Fetal , Ácido Fólico/administração & dosagem , Regulação da Expressão Gênica no Desenvolvimento , Fenômenos Fisiológicos da Nutrição Materna , Animais , Animais Recém-Nascidos , Encéfalo/embriologia , Encéfalo/crescimento & desenvolvimento , Encéfalo/metabolismo , Receptor alfa de Estrogênio/agonistas , Receptor alfa de Estrogênio/antagonistas & inibidores , Receptor alfa de Estrogênio/genética , Receptor alfa de Estrogênio/metabolismo , Feminino , Ácido Fólico/sangue , Ácido Fólico/metabolismo , Ácido Fólico/uso terapêutico , Fator de Crescimento Insulin-Like II/agonistas , Fator de Crescimento Insulin-Like II/antagonistas & inibidores , Fator de Crescimento Insulin-Like II/genética , Fator de Crescimento Insulin-Like II/metabolismo , Fígado/metabolismo , Proteínas do Tecido Nervoso/agonistas , Proteínas do Tecido Nervoso/antagonistas & inibidores , Proteínas do Tecido Nervoso/genética , Proteínas do Tecido Nervoso/metabolismo , Defeitos do Tubo Neural/sangue , Defeitos do Tubo Neural/metabolismo , Defeitos do Tubo Neural/prevenção & controle , Neurônios/citologia , Neurônios/metabolismo , Especificidade de Órgãos , Receptores Ativados por Proliferador de Peroxissomo/agonistas , Receptores Ativados por Proliferador de Peroxissomo/antagonistas & inibidores , Receptores Ativados por Proliferador de Peroxissomo/genética , Receptores Ativados por Proliferador de Peroxissomo/metabolismo , Gravidez , Distribuição Aleatória , Ratos Sprague-Dawley , Receptores de Glucocorticoides/agonistas , Receptores de Glucocorticoides/antagonistas & inibidores , Receptores de Glucocorticoides/genética , Receptores de Glucocorticoides/metabolismoRESUMO
Folylpolyglutamate synthase (FPGS) plays a critical role in intracellular folate homeostasis. FPGS-induced polyglutamylated folates are better substrates for several enzymes involved in the generation of S-adenosylmethionine, the primary methyl group donor, and hence FPGS modulation may affect DNA methylation. DNA methylation is an important epigenetic determinant in gene expression and aberrant DNA methylation is mechanistically linked cancer development. We investigated whether FPGS modulation would affect global and gene-specific promoter DNA methylation with consequent functional effects on gene expression profiles in HCT116 colon and MDA-MB-435 breast cancer cells. Although FPGS modulation altered global DNA methylation and DNA methyltransferases (DNMT) activity, the effects of FPGS modulation on global DNA methylation and DNMT activity could not be solely explained by intracellular folate concentrations and content of long-chain folylpolyglutamates, and it may be cell-specific. FPGS modulation influenced differential gene expression and promoter cytosine-guanine dinucleotide sequences (CpG) DNA methylation involved in cellular development, cell cycle, cell death and molecular transport. Some of the altered gene expression was associated with promoter CpG DNA methylation changes. In both the FPGS-overexpressed HCT116 and MDA-MB-435 cell lines, we identified several differentially expressed genes involved in folate biosynthesis and one-carbon metabolism, which might in part have contributed to the observed increased efficacy of 5-fluorouracil in response to FPGS overexpression. Our data suggest that FPGS modulation affects global and promoter CpG DNA methylation and expression of several genes involved in important biological pathways. The potential role of FPGS modulation in DNA methylation and its associated downstream functional effects warrants further studies.
Assuntos
Neoplasias da Mama/genética , Neoplasias do Colo/genética , Metilação de DNA/genética , Regulação Neoplásica da Expressão Gênica , Peptídeo Sintases/metabolismo , Neoplasias da Mama/enzimologia , Neoplasias da Mama/patologia , Linhagem Celular Tumoral , Neoplasias do Colo/enzimologia , Neoplasias do Colo/patologia , Feminino , HumanosRESUMO
BACKGROUND: B vitamins [vitamins B-6, B-9 (folate), and B-12] play important roles in nucleotide biosynthesis and biological methylation reactions, aberrancies of which have all been implicated in carcinogenesis. In the general population, evidence has suggested that high circulating folate and folic acid (synthetic form of folate) supplement use may increase breast cancer risk, but the role of folate in BRCA-associated breast cancer is not clear. OBJECTIVE: We prospectively evaluated the relation between plasma folate, pyridoxal 5'-phosphate (PLP; the biologically active form of vitamin B-6), and vitamin B-12 and breast cancer risk in women with a BRCA1/2 mutation. DESIGN: Baseline blood samples and biennial follow-up questionnaires were available for 164 BRCA1/2-mutation carriers with no previous history of cancer other than nonmelanoma skin cancer. Plasma folate, PLP, and vitamin B-12 concentrations were categorized dichotomously as high compared with low based on the upper 25% and the lower 75% of distribution, respectively. Cox proportional hazards were used to estimate the HR and 95% CI for the association between plasma biomarkers of each B vitamin and incident breast cancer. RESULTS: Over a mean follow-up of 6.3 y, 20 incident primary invasive breast cancers were observed. Women with high plasma folate concentrations (>24.4 ng/mL) were associated with significantly increased breast cancer risk (HR: 3.20; 95% CI: 1.03, 9.92; P = 0.04, P-trend across quintiles = 0.07) compared with that of women with low plasma folate concentrations (≤24.4 ng/mL). Plasma PLP and vitamin B-12 concentrations were not associated with breast cancer risk. CONCLUSIONS: Our data suggest that elevated plasma folate concentrations may be associated with increased risk of breast cancer in women with a BRCA1/2 mutation. Additional studies with a larger sample size and longer follow-up periods are warranted to clarify the relation between folate status and breast cancer risk in high-risk women.
Assuntos
Proteína BRCA1/genética , Proteína BRCA2/genética , Neoplasias da Mama/etiologia , Suplementos Nutricionais/efeitos adversos , Ácido Fólico/efeitos adversos , Alimentos Fortificados/efeitos adversos , Predisposição Genética para Doença , Adulto , Proteína BRCA1/metabolismo , Proteína BRCA2/metabolismo , Biomarcadores/sangue , Neoplasias da Mama/sangue , Neoplasias da Mama/epidemiologia , Neoplasias da Mama/genética , Estudos de Coortes , Feminino , Ácido Fólico/sangue , Seguimentos , Humanos , Incidência , Mutação , Ontário/epidemiologia , Estudos Prospectivos , Fosfato de Piridoxal/sangue , Risco , Vitamina B 12/sangue , Deficiência de Vitamina B 12/fisiopatologia , Deficiência de Vitamina B 6/fisiopatologiaRESUMO
BACKGROUND: Mandatory fortification, prevalent supplement use, and public health guidelines recommending periconceptional supplementation have increased folic acid intakes in North American pregnant women. However, the effects of increased folic acid intakes during pregnancy on maternal and cord blood folate concentrations have not been well established. OBJECTIVES: In this prospective study, we determined maternal and cord blood concentrations of folate and unmetabolized folic acid (UMFA) in a cohort of pregnant Canadian women and their newborns and examined the effect of maternal intakes of folate and folic acid and fetal genetic variants in folate metabolism on folate status. DESIGN: Folate and folic acid intakes of 368 Canadian pregnant women were assessed in early (0-16 wk) and late (23-37 wk) pregnancy. Blood concentrations of folate and UMFA were measured with the use of immunoassays and liquid chromatography-mass spectrometry, respectively, in maternal samples in early pregnancy (12-16 wk), at delivery (28-42 wk), and in cord blood. Four fetal genetic variants of the 5,10-methylenetetrahydrofolate reductase (MTHFR) and dihydrofolate reductase (DHFR) genes were assessed for their association with cord blood concentrations of folate and UMFA. RESULTS: Geometric mean (95% CI) maternal red blood cell (RBC) folate concentrations were 2417 nmol/L (2362, 2472 nmol/L ) and 2793 nmol/L (2721, 2867 nmol/L ) in early pregnancy and at delivery, respectively. The mean (95% CI) cord RBC folate concentration was 2689 nmol/L (2614, 2765 nmol/L). UMFA was detectable in >90% of maternal and cord plasma samples. Although 3 fetal MTHFR and DHFR genetic variants had no effect, the fetal MTHFR 677TT genotype was associated with significantly lower cord serum (P = 0.03) and higher cord RBC (P = 0.02) folate concentrations than those of the wild type. CONCLUSIONS: Notwithstanding differences in assays, maternal and cord RBC folate and plasma UMFA concentrations were higher than previously reported values. Functional ramifications of high folate and UMFA concentrations in maternal and fetal circulation warrant additional investigation because an excess folate status may affect long-term health outcomes of the offspring. This study was registered at www.clinicaltrials.gov as NCT02244684.
Assuntos
Sangue Fetal/química , Ácido Fólico/sangue , Fenômenos Fisiológicos da Nutrição Materna , Adulto , Canadá , Suplementos Nutricionais , Ingestão de Energia , Feminino , Ácido Fólico/administração & dosagem , Ácido Fólico/efeitos adversos , Frequência do Gene , Variação Genética , Genótipo , Homocisteína/sangue , Humanos , Modelos Logísticos , Metilenotetra-Hidrofolato Redutase (NADPH2)/genética , Metilenotetra-Hidrofolato Redutase (NADPH2)/metabolismo , Pessoa de Meia-Idade , Avaliação Nutricional , Polimorfismo de Nucleotídeo Único , Gravidez , Estudos Prospectivos , Inquéritos e Questionários , Tetra-Hidrofolato Desidrogenase/genética , Tetra-Hidrofolato Desidrogenase/metabolismo , Adulto JovemRESUMO
γ-Glutamyl hydrolase (GGH) plays an important role in folate homeostasis by catalyzing hydrolysis of polyglutamylated folate into monoglutamates. Polyglutamylated folates are better substrates for several enzymes involved in the generation of S-adenosylmethionine, the primary methyl group donor, and hence, GGH modulation may affect DNA methylation. DNA methylation is an important epigenetic determinant in gene expression, in the maintenance of DNA integrity and stability, and in chromatin modifications, and aberrant or dysregulation of DNA methylation has been mechanistically linked to the development of human diseases including cancer. Using a recently developed in vitro model of GGH modulation in HCT116 colon and MDA-MB-435 breast cancer cells, we investigated whether GGH modulation would affect global and gene-specific DNA methylation and whether these alterations were associated with significant gene expression changes. In both cell lines, GGH overexpression decreased global DNA methylation and DNA methyltransferase (DNMT) activity, while GGH inhibition increased global DNA methylation and DNMT activity. Epigenomic and gene expression analyses revealed that GGH modulation influenced CpG promoter DNA methylation and gene expression involved in important biological pathways including cell cycle, cellular development, and cellular growth and proliferation. Some of the observed altered gene expression appeared to be regulated by changes in CpG promoter DNA methylation. Our data suggest that the GGH modulation-induced changes in total intracellular folate concentrations and content of long-chain folylpolyglutamates are associated with functionally significant DNA methylation alterations in several important biological pathways.
RESUMO
Folate supplementation may reduce the risk of colorectal dysplasia and cancer in subjects with chronic ulcerative colitis (UC). The interleukin (IL) 2- and beta(2)-microglobulin (beta(2)m)-deficient (IL-2(null) x beta(2)m(null)) mice spontaneously develop colon cancer in the setting of chronic UC. This study investigated the effects of dietary folate on the development of UC-associated colon cancer in the IL-2(null) x beta(2)m(null) mice. Weaning IL-2(null) x beta(2)m(null) mice were randomized to receive 0 (deficient; n = 40), 2 (basal requirement; control; n = 46), or 8 (supplemented; n = 36) mg folate/kg diet for 32 weeks. At necropsy, all macroscopic colonic tumors were identified and histologically classified as dysplasia or adenocarcinoma. The incidence of high-grade lesions (high-grade dysplasia/carcinoma in situ and invasive adenocarcinoma) in the folate-supplemented group was 46% lower than that in the control group (35.3% versus 65.1%, P = 0.009). The incidence of high-grade lesions in the folate-deficient group was also 49% lower than that in the control group (33.3% versus 65.1%, P = 0.007). The higher mortality rate in the folate-deficient group compared with the other two groups (25% versus 6.5% and 5.6%, P < 0.02) partially accounted for the low incidence of high-grade lesions in this group. These data indicate that dietary folate supplementation at 4x the basal dietary requirement significantly suppresses UC-associated colorectal carcinogenesis in the IL-2(null) x beta(2)m(null) mice. These data also suggest that folate deficiency may inhibit colorectal carcinogenesis in chronic UC. However, the high mortality observed in the folate-deficient group precludes a definitive conclusion concerning the effect of folate deficiency on UC-associated colorectal carcinogenesis in this model.
Assuntos
Colite Ulcerativa/prevenção & controle , Neoplasias Colorretais/prevenção & controle , Ácido Fólico/farmacologia , Interleucina-2/genética , Microglobulina beta-2/genética , Animais , Transformação Celular Neoplásica , Colite Ulcerativa/etiologia , Colite Ulcerativa/veterinária , Neoplasias Colorretais/etiologia , Neoplasias Colorretais/fisiopatologia , Dieta , Suplementos Nutricionais , Modelos Animais de Doenças , Deficiência de Ácido Fólico/complicações , Deficiência de Ácido Fólico/veterinária , Humanos , Camundongos , Camundongos Endogâmicos C57BLRESUMO
Folic acid supplementation may prevent the development of cancer in normal tissues but may promote the progression of established (pre)neoplastic lesions. However, whether or not folic acid supplementation can promote the progression of established (pre)neoplastic mammary lesions is unknown. This is a critically important issue because breast cancer patients and survivors in North America are likely exposed to high levels of folic acid owing to folic acid fortification and widespread supplemental use after cancer diagnosis. We investigated whether folic acid supplementation can promote the progression of established mammary tumors. Female Sprague-Dawley rats were placed on a control diet and mammary tumors were initiated with 7,12-dimethylbenza[a]anthracene at puberty. When the sentinel tumor reached a predefined size, rats were randomized to receive a diet containing the control, 2.5x, 4x, or 5x supplemental levels of folic acid for up to 12 weeks. The sentinel mammary tumor growth was monitored weekly. At necropsy, the sentinel and all other mammary tumors were analyzed histologically. The effect of folic acid supplementation on the expression of proteins involved in proliferation, apoptosis, and mammary tumorigenesis was determined in representative sentinel adenocarcinomas. Although no clear dose-response relationship was observed, folic acid supplementation significantly promoted the progression of the sentinel mammary tumors and was associated with significantly higher sentinel mammary tumor weight and volume compared with the control diet. Furthermore, folic acid supplementation was associated with significantly higher weight and volume of all mammary tumors. The most significant and consistent mammary tumor-promoting effect was observed with the 2.5x supplemental level of folic acid. Folic acid supplementation was also associated with an increased expression of BAX, PARP, and HER2. Our data suggest that folic acid supplementation may promote the progression of established mammary tumors. The potential tumor-promoting effect of folic acid supplementation in breast cancer patients and survivors needs further clarification.
Assuntos
Adenocarcinoma/patologia , Suplementos Nutricionais/efeitos adversos , Ácido Fólico/efeitos adversos , Neoplasias Mamárias Experimentais/patologia , Proteínas de Neoplasias/genética , 9,10-Dimetil-1,2-benzantraceno , Adenocarcinoma/induzido quimicamente , Adenocarcinoma/genética , Adenocarcinoma/metabolismo , Animais , Progressão da Doença , Feminino , Expressão Gênica/efeitos dos fármacos , Humanos , Neoplasias Mamárias Experimentais/induzido quimicamente , Neoplasias Mamárias Experimentais/genética , Neoplasias Mamárias Experimentais/metabolismo , Proteínas de Neoplasias/metabolismo , Poli(ADP-Ribose) Polimerases , Ratos , Ratos Sprague-Dawley , Receptor ErbB-2 , Carga Tumoral/efeitos dos fármacos , Proteína X Associada a bcl-2RESUMO
SCOPE: Intrauterine and early-life exposure to folic acid has significantly increased in North America owing to folic acid fortification, widespread supplemental use, and periconceptional supplementation. We investigated the effect of maternal and postweaning folic acid supplementation on DNA methylation in the rat offspring. METHODS AND RESULTS: Female rats were placed on a control or folic acid-supplemented diet during pregnancy and lactation. At weaning, pups from each maternal diet group were randomized to the control or supplemented diet for 11 weeks. At weaning, maternal folic acid supplementation significantly decreased global (p < 0.001) and site-specific DNA methylation of the Ppar-γ, ER-α, p53, and Apc genes (p < 0.05) in the liver. At 14 weeks of age, postweaning, but not maternal, folic acid supplementation significantly decreased global DNA methylation (p < 0.05). At 14 weeks of age, both maternal and postweaning folic acid supplementation significantly increased DNA methylation of the Ppar-γ, p53, and p16 genes (p < 0.05) whereas only postweaning FA supplementation significantly increased DNA methylation of the ER-α and Apc genes (p < 0.05). CONCLUSION: Our data suggest that maternal and postweaning folic acid supplementation can significantly modulate global and gene-specific DNA methylation in the rat offspring. The functional ramifications of the observed DNA methylation changes need to be determined in future studies.