大橋 鉱二

Epidemiological and experimental studies have shown that low methylmercury (MeHg) exposure causes cytotoxic effects. As to such cytotoxic effects, we have supposed that not only MeHg itself but also MeHg interacting with living environmental factors may cause cytotoxic effects. MeHg exposure is known to induce oxidative stress and cell death via ferroptosis in hepatocytes. In this study, we examined whether MeHg exposure followed by palmitic acid (PA) exposure at low non-toxic concentrations cause oxidative stress and cell death in HepG2 cells. In HepG2 cells combinedly exposed to MeHg and PA at low non-toxic concentrations, cell viability and glutathione peroxidase 4 expression levels were significantly decreased, while reactive oxygen species level was significantly increased. Ferrostatin-1 pretreatment suppressed oxidative stress and cell death found in the HepG2 cells. These results indicate that combined exposure to MeHg and PA at low non-toxic concentrations induces oxidative stress associated cell death in HepG2 cells.

BACKGROUND: Cardiovascular disease (CVD) remains a leading cause of death in Japan. Although several CVD risk scores tailored for Japanese individuals have been developed, no tools are available to estimate these scores at the population level. We developed the "Jcvrisk" R package, which integrates four major Japanese CVD risk models recommended by the clinical guideline. As a showcase, we applied the Jcvrisk package to longitudinal population-based study to evaluate trends in estimated different risk scores. METHODS: We used longitudinal data from the Yakumo Study, an annual health checkup for residents in Yakumo, Hokkaido. This package includes four risk models with 14 risk scores from representative cardiovascular cohort studies, including three EPOCH scores, one Hisayama score, two Suita scores, and eight JALS scores. For temporal comparisons of CVD risk scores, we summarized scores from 2000 to 2020 every five years. RESULTS: The mean age of participants throughout all study years was around 60 years old. Most risk factors did not change remarkably over the 20 years, with only a decrease in smoking prevalence and an increase in high density lipoprotein cholesterol (HDL-C). However, all CVD risk scores consistently indicated an upward trend in 10-year CVD risk. CONCLUSIONS: Jcvrisk package includes functions to calculate CVD risk scores for Japanese adults. The package serves as a valuable tool for researchers and policymakers aiming to assess and monitor cardiovascular risk at both individual and population levels in Japan.

BACKGROUND: Current evidence suggests an increased risk for cancer mortality in those with low aryl hydrocarbon receptor repressor (AHRR) DNA methylation (DNAm) levels. Therefore, AHRR DNAm could identify a more "fragile" group at risk for cancer mortality than questionnaire-based evaluations. Given this, the aim was to identify "fragile" groups at risk of cancer mortality by integrating questionnaire-based smoking indices and leukocyte AHRR DNAm levels in the Japanese population. METHODS: The target population was 795 participants without a clinical history who underwent a health checkup in 1990. They were followed for up to 30 years for mortality. The AHRR DNAm levels in leukocytes were measured by the pyrosequencing method. HRs for cancer mortality were calculated using a Cox proportional hazards model. RESULTS: Significantly higher HRs for all-cancer mortality were observed in low AHRR DNAm groups regardless of smoking intensity [pack-years <20: 3.69 (1.46-9.37); pack-years ≥20: 2.13 (1.11-4.09)]. Compared with current smokers, significantly lower HRs for all-cancer mortality were observed in the group with high AHRR DNAm regardless of years since quitting [YSQ ≤10: 0.13 (0.02-0.96); YSQ >10: 0.28 (0.08-0.98)]. Even for YSQ greater than 10, there was no significant mortality risk reduction in the low AHRR DNAm group. CONCLUSIONS: The population with low AHRR DNAm levels had a higher risk of cancer mortality even with low smoking exposure. Furthermore, no significant risk reduction was observed in former smokers with low AHRR DNAm levels. IMPACT: AHRR DNAm levels in leukocytes may help identify groups at risk for cancer mortality overlooked by questionnaire-based smoking indices.

BACKGROUND: Incidence of ischemic stroke increased after natural disasters. Therefore, it is important to establish a means of identifying high-risk populations for incident stroke. We performed a prospective cohort study to examine whether these three cardiovascular disease-related miRNAs (miR-126, miR-197, and miR-223) are associated with incident stroke among elderly survivors of the Great East Japan Earthquake. METHOD: This cohort study was conducted using the data of 1192 survivors of the Great East Japan Earthquake over 60-years old who underwent a health check-up in December 2011. We followed up participants to record stroke cases until the end of 2016. We measured serum miRNAs by quantitative real-time polymerase chain reaction. HRs for incident stroke were estimated by Cox proportional hazard regression analyses. RESULT: The serum miR-197 level was significantly associated with the incident stroke; the HR per one standard deviation change in the miR-197 level was 1.65 (95% confidence interval: 1.19 - 2.30). In contrast, the levels of miR-126 and miR-223 were not associated with the incident stroke. CONCLUSION: We found that a higher miR-197 level is associated with an increased risk of incident stroke; thus, miR-197 is expected to be useful as a predictive biomarker.

Nutritional researches have successfully used animal models to gain new insights into nutrient action. However, comprehensive descriptions of their molecular mechanisms of action remain elusive as appropriate in vitro evaluation systems are lacking. Organoid models can mimic physiological structures and reproduce in vivo functions, making them increasingly utilized in biomedical research for a better understand physiological and pathological phenomena. Therefore, organoid modeling can be a powerful approach for to understand the molecular mechanisms of nutrient action. The present study aims to demonstrate the utility of organoids in nutritional research by further investigating the molecular mechanisms responsible for the negative effects of fructose intake using liver organoids. Here, we treated liver organoids with fructose and analyzed their gene expression profiles and DNA methylation levels. Microarray analysis demonstrated that fructose-treated organoids exhibited increased selenoprotein p (Sepp1) gene expression, whereas pyrosequencing assays revealed reduced DNA methylation levels in the Sepp1 region. These results were consistent with observations using hepatic tissues from fructose-fed rats. Conversely, no differences in Sepp1 mRNA and DNA methylation levels were observed in two-dimensional cells. These results suggest that organoids serve as an ideal in vitro model to recapitulate in vivo tissue responses and help to validate the molecular mechanisms of nutrient action compared to conventional cellular models.

Thioredoxin-interacting protein (TXNIP) plays an important role in glucose metabolism, and its expression is regulated by DNA methylation (DNAm). Although the association between TXNIP DNAm and type 2 diabetes mellitus has been demonstrated in studies with a cross-sectional design, prospective studies are needed. We therefore examined the association between TXNIP DNAm levels and longitudinal changes in glycemic traits by conducting a longitudinal study involving 169 subjects who underwent two health checkups in 2015 and 2019. We used a pyrosequencing assay to determine TXNIP DNAm levels in leukocytes (cg19693031). Logistic regression analyses were performed to assess the associations between dichotomized TXNIP DNAm levels and marked increases in glycemic traits. At four years, the TXNIP DNA hypomethylation group had a higher percentage of changes in fasting plasma glucose (FPG) and hemoglobin A1c (HbA1c) compared to those in the hypermethylation group. The adjusted odds ratios for FPG and HbA1c levels were significantly higher in the TXNIP DNA hypomethylation group than in the hypermethylation group. We found that TXNIP DNA hypomethylation at baseline was associated with a marked increase in glycemic traits. Leukocyte TXNIP DNAm status could potentially be used as an early biomarker for impaired glucose homeostasis.

AIMS: The developmental origin of health and disease (DOHaD) theory postulates that poor nutrition during fetal life increases the risk of disease later in life. Excessive fructose intake has been associated with obesity, diabetes, and nonalcoholic fatty liver disease, and maternal fructose intake during pregnancy has been shown to affect offspring health. In this study, we investigated the effects of high maternal fructose intake on the liver stem/progenitor cells of offspring. MAIN METHOD: A fructose-based DOHaD model was established using Sprague-Dawley rats. Small hepatocytes (SHs), which play an important role in liver development and regeneration, were isolated from the offspring of dams that were fed a high-fructose corn syrup (HFCS) diet. The gene expression and DNA methylation patterns were analyzed on postnatal day (PD) 21 and 60. KEY FINDINGS: Maternal HFCS intake did not affect body weight or caloric intake, but differences in gene expression and DNA methylation patterns were observed in the SHs of offspring. Functional analysis revealed an association between metabolic processes and ion transport. SIGNIFICANCE: These results suggest that maternal fructose intake affects DNA methylation and gene expression in the liver stem/progenitor cells of offspring. Furthermore, the prolonged retention of these changes in gene expression and DNA methylation in adulthood (PD 60) suggests that maternal fructose intake may exert lifelong effects. These findings provide insights into the DOHaD for liver-related disorders and highlight the importance of maternal nutrition for the health of the next generation.

OBJECTIVES: The mitochondrial DNA (mtDNA) is unique and circular with multiple copies of the genome. The lower mtDNA copy number (mtDNA-CN) in leukocytes is associated with the risk of all-cause mortality. However, its long-term association is unknown. Thus, the study examined the association between mtDNA-CN and the risk of all-cause mortality in a long-term follow-up study in the Japanese population. DESIGN: This longitudinal study included the study cohort from an annual, population-based health checkup in the town of Yakumo, Hokkaido, Japan. SETTING AND PARTICIPANTS: 814 participants (baseline age range: 38-80 years, mean: 56.3 years) were included in this study in 1990. They were followed-up regarding mortality for about 30 years (median: 28.1 years) till 2019. MEASURES: The genomic DNA was extracted from peripheral blood mononuclear cells and the mtDNA-CN was measured using real-time polymerase chain reaction. The level of the mtDNA-CN was divided into tertiles (low, middle, and high). The participants were categorized based on their age into middle-aged (<60 years old) or old-aged (≥60 years old). Survival analysis was performed for tertile of mtDNA-CN and compared using the log-rank test. Univariate and multivariable Cox proportional hazard regression analyses were performed to assess the association between mtDNA-CN and all-cause mortality. The model adjusted with age, sex, body mass index, systolic blood pressure, smoking habit, alcohol consumption, exercise habit, and education level. RESULTS: The low levels of mtDNA-CN resulted in a significant decrease in cumulative survival rate (P <  0.05). The risk of mortality was significantly higher in the middle-aged cohort when mtDNA-CN levels were low (hazard ratios [95% confidence intervals]: 1.98 [1.10-3.56]). CONCLUSION: This study demonstrated that leukocyte mtDNA-CN is associated with future mortality risk. Our study findings may lead to further research on the early prediction of mortality and its underlying mechanisms.

Background: Carotenoids have been reported to exert protective effects against age-related diseases via changes in DNA methylation. Although lower thioredoxin-interacting protein (TXNIP) DNA methylation is associated with age-related diseases, only a few studies have investigated the factors influencing TXNIP DNA methylation. Carotenoids may be a factor linking TXNIP to specific pathophysiological functions. The aim of this study was to examine whether serum carotenoid levels are associated with TXNIP DNA methylation levels. Methods: We conducted a cross-sectional study using 376 health examination participants (169 men). DNA methylation levels were determined using a pyrosequencing assay. Serum carotenoid levels were determined by high-performance liquid chromatography. Multivariable regression analyses were performed to examine the associations between TXNIP DNA methylation levels and serum carotenoid levels with adjustment for age, BMI, HbA1c, CRP, smoking habits, alcohol consumption, exercise habits, and percentage of neutrophils. Results: Multiple linear regression analyses showed that TXNIP DNA methylation levels were positively associated with serum levels of zeaxanthin/lutein (β [95%CI]: 1.935 [0.184, 3.685]), β-cryptoxanthin (1.447 [0.324, 2.570]), α-carotene (1.061 [0.044, 2.077]), β-carotene (1.272 [0.319, 2.226]), total carotenes (1.255 [0.040, 2.469]), total xanthophylls (2.133 [0.315, 3.951]), provitamin A (1.460 [0.402, 2.519]), and total carotenoids (1.972 [0.261, 3.683]) in men (all p<0.05). Of these, provitamin A showed the stronger association (standardized β=0.216). No significant association of TXNIP DNA methylation and serum carotenoid was observed in women. Conclusions: The findings of this study suggest that carotenoid intake may protect against age-related diseases by altering TXNIP DNA methylation status in men.

BACKGROUND: Epigenetic studies have reported relationships between dietary nutrient intake and methylation levels. However, genetic variants that may affect DNA methylation (DNAm) pattern, called methylation quantitative loci (mQTL), are usually overlooked in these analyses. We investigated whether mQTL change the relationship between dietary nutrient intake and leukocyte DNAm levels with an example of estimated fatty acid intake and ATP-binding cassette transporter A1 (ABCA1). METHODS: A cross-sectional study on 231 participants (108 men, mean age: 62.7 y) without clinical history of cancer and no prescriptions for dyslipidemia. We measured leukocyte DNAm levels of 8 CpG sites within ABCA1 gene by pyrosequencing method and used mean methylation levels for statistical analysis. TaqMan assay was used for genotyping a genetic variant of ABCA1 (rs1800976). Dietary fatty acid intake was estimated with a validated food frequency questionnaire and adjusted for total energy intake by using residual methods. RESULTS: Mean ABCA1 DNAm levels were 5% lower with the number of minor alleles in rs1800976 (CC, 40.6%; CG, 35.9%; GG, 30.6%). Higher dietary n-3 PUFA intake was associated with lower ABCA1 DNAm levels (1st (ref) vs. 4th, β [95% CI]: -2.52 [-4.77, -0.28]). After controlling for rs180076, the association between dietary n-3 PUFA intake and ABCA1 DNAm levels was attenuated, but still showed an independent association (1st (ref) vs. 4th, β [95% CI]: -2.00 [-3.84, -0.18]). The interaction of mQTL and dietary n-3 PUFA intake on DNAm levels was not significant. CONCLUSIONS: This result suggested that dietary n-3 PUFA intake would be an independent predictor of DNAm levels in ABCA1 gene after adjusting for individual genetic background. Considering mQTL need to broaden into other genes and nutrients for deeper understanding of DNA methylation, which can contribute to personalized nutritional intervention.

Background: The increasing prevalence of non-alcoholic fatty liver disease (NAFLD) has become a global health problem. NAFLD has few initial symptoms and may be difficult to detect early, so there is need for a minimally invasive early detection marker. We hypothesized that miR-122 and miR-20a levels combined, as the miR-122/miR-20a ratio might detect NAFLD more sensitively. Methods: This study involved 167 participants with low alcohol intake. Those who had an increase in echogenicity of the liver parenchyma and hepato-renal contrast on ultrasonography were classified as the NAFLD group (n = 44), which was further classified into mild (n = 26) and severe (n = 18) groups based on echogenic intensity and hepatic vessel and diaphragm visualization. Participants without fatty liver were included in the normal group, except for those with an abnormal body mass index, glycated hemoglobin, and systolic blood pressure (n = 123) values. Serum miR-122 and miR-20a expression levels in participants were measured by real-time polymerase chain reaction, and the miR-122/miR-20a was calculated. Results: In the NAFLD group, miR-122 expression was significantly higher and the miR-20a was significantly lower than in the normal group, in agreement with previous studies. miR-122/miR-20a was also significantly higher in the NAFLD group. Receiver operating characteristic curve analysis was performed with miR-122/miR-20a as an NAFLD detection marker, and the area under the curve of miR-122/miR-20a was significantly larger than that of miR-122 or miR-20a alone. Conclusions: The miR-122/miR-20a ratio, combined with miR-122 and miR-20a levels, is a useful biomarker to detect NAFLD with high sensitivity.

OBJECTIVES: The adverse health effects of consuming sugar-sweetened beverages have been studied worldwide. However, no recent report on the actual sugar contents of Japanese sugar-sweetened beverages is available. Therefore, we analyzed the glucose, fructose, and sucrose contents of common Japanese beverages. METHODS: The glucose, fructose, and sucrose contents of 49 beverages (8 energy drinks, 11 sodas, 4 fruit juices, 7 probiotic drinks, 4 sports drinks, 5 coffee drinks, 6 green tea drinks, and 4 black tea drinks) were determined using enzymatic methods. RESULTS: Three zero calorie drinks, 2 sugarless coffee drinks, and 6 green tea drinks contained no sugar. Three coffee drinks contained only sucrose. The orders of median glucose, fructose, and sucrose contents in the categories of beverages containing sugars were as follows: for glucose, fruit juice > energy drink ≥ soda ≫ probiotic drink > black tea drink > sports drink; for fructose, probiotic drink ≥ energy drink > fruit juice > soda ≫ sports drink > black tea drink; and for sucrose, black tea drink > energy drink ≥ probiotic drink > fruit juice > soda > coffee drink ≫ sports drink. The total fructose as a percentage of the total sugar content in the 38 sugar-containing beverages was between 40% and 60%. The total sugar content analyzed was not always equivalent to the carbohydrate content indicated on the nutrition label. CONCLUSIONS: These results indicate that information on the actual sugar content of common Japanese beverages is necessary for the exact assessment of beverage-derived sugar intake.

We previously reported that maternal fructose consumption increases blood corticosterone levels in rat offspring. However, the underlying mechanism of action remains unclear. In the present study, we aimed to elucidate the molecular mechanism by which maternal high-fructose corn syrup (HFCS) intake increases circulating GC levels in rat offspring (GC; corticosterone in rodents and cortisol in humans). Female Sprague Dawley rats received HFCS solution during gestation and lactation. The male offspring were fed distilled water from weaning to 60 days of age. We investigated the activities of GC-metabolizing enzymes (11β-Hsd1 and 11β-Hsd2) in various tissues (i.e., liver, kidney, adrenal glands, muscle, and white adipose tissue) and epigenetic modification. 11β-Hsd2 activity decreased in the kidney of the HFCS-fed dams. Moreover, the epigenetic analysis suggested that miR-27a reduced Hsd11b2 mRNA expression in the kidney of offspring. Maternal HFCS-induced elevation of circulating GC levels in offspring may be explained by a decrease in 11β-Hsd2 activity via renal miR-27a expression. The present study may allow us to determine one of the mechanisms of GC elevation in rat offspring that is often observed in the developmental origins of the health and disease (DOHaD) phenomenon.

High-fructose corn syrup (HFCS) is consumed worldwide. However, it has been demonstrated that an increased intake of sweetened beverages, including those sweetened using fructose, is associated with the development of childhood obesity. It is unknown why the negative effects of fructose are stronger in young persons than in elderly individuals. In recent years, mitochondria have been identified as 1 of the targets of the negative effects of fructose; they possess their own genome called mitochondrial DNA (mtDNA), which encodes genes involved in metabolic functions. We hypothesized that HFCS intake affects mtDNA in the livers of rats, and that the intensity of these effects is age-dependent. The experimental period was divided into 3 parts: childhood and adolescence (postnatal day [PD] 21-60), young adulthood (PD61-100), and adulthood (PD101-140). Rats in the different age groups were assigned to receive either water (control group [CONT]) or a 20% HFCS solution (HFCS). The hepatic mtDNA copy number of the HFCS group was higher than that of the CONT group in childhood and adolescence. In addition, the mtDNA methylation level was increased in the HFCS group in the same experimental period. No significant differences were observed between the CONT and HFCS groups during the other experimental periods. We demonstrated that HFCS has the strongest effect on mtDNA during childhood and adolescence, suggesting a need to analyze the HFCS intake of young people.

Concerns about the negative intergenerational effects of excessive fructose intake are being raised, with evidence suggesting that prenatal fructose intake increases susceptibility to metabolic and cognitive dysfunction later in life. In the present study, we hypothesized that prenatal and postnatal fructose intake acts synergistically to impact on hippocampus of adult offspring. Female Sprague-Dawley rats received distilled water or 20% high-fructose corn syrup (HFCS) solution in addition to standard chow throughout gestation and lactation. Male offspring were weaned at postnatal day 21 (PD21) and were randomized to receive distilled water or 20% HFCS solution until PD60. The following experimental groups were: CC: distilled water dams and post-weaning distilled water, CH: distilled water dams and post-weaning HFCS solution, HC: HFCS solution dams and post-weaning distilled water and HH: HFCS solution dams and post-weaning HFCS solution. The synergistic effect of maternal and post-weaning HFCS intake on the hippocampus was investigated by studying the expression of pro-inflammatory cytokine genes (Tnfa, Il1b, and Il6). At weaning, expression levels of pro-inflammatory cytokines between the offspring of the distilled water and HFCS solution fed dams were not significantly different. At PD60, Tnfa expression was significantly higher in the HH group than in the CC, HC and CH groups, whereas no significant differences were found between the CC, HC, and CH groups. These results suggest that postnatal fructose intake negatively impacts the hippocampus by acting synergistically with prenatal fructose intake.

BACKGROUND: Previous studies have proposed different formulas of estimating glomerular filtration rate (eGFR) among clinical patients. The comprehensive comparison of eGFR formulas is not well established in a Japanese population. We compared eGFR values and chronic kidney disease (CKD) classification of nine different eGFR in a Japanese general population sample. METHODS: We analyzed 469 Japanese community-dwelling adults (184 men) without any self-reported kidney disease. GFR estimated using the 4- and 6-parameter Modification of Diet in Renal Disease (MDRD) formulas (MDRD4 and MDRD6); the CKD-EPI formulas based on creatinine with (CKD-EPI-2009) and without race coefficient (CKD-EPI-2021), on cystatin C (CKD-EPI-Cys), on both (CKD-EPI-CreCys); the Japanese creatinine-based formula (JPN-Cre), cystatin C-based formula (JPN-Cys), and modified CKD-EPI formula (JPN-CKD-EPI). CKD stages were defined by KDIGO guidelines (eGFR < 60 ml/min/1.73 m2). RESULTS: eGFRJPN-Cre (mean = 71.2; SD = 14.3) were much lower than eGFRCKD-EPI-2021 (mean = 94.2; SD = 12.7), while eGFRJPN-Cys (mean = 102.8; SD = 24.2) was comparable to the MDRD and CKD-EPI formulas. The difference between eGFRCKD-EPI-2021 and eGFRJPN-Cre showed a V-shaped distribution across eGFR levels, indicating complex errors between these formulas. We observed very low agreement in CKD classification between eGFRJPN-Cre and the eGFRCKD-EPI-2021 (kappa = 0.13; 95% confidence interval: 0.06, 0.23). CONCLUSIONS: JPN-Cre was substantially different from the CKD-EPI formula without race term (CKD-EPI-2021), which means that it is impossible to recalibrate those with a simple coefficient. Although a comparison with measured GFR should be necessary, choice of the estimation method needs caution in clinical decision-making and academic research.

The consumption of high-fructose corn syrup (HFCS) has been increasing in recent decades, especially among children. Some reports suggest that children and adolescents are more sensitive to the adverse effects of fructose intake than adults. However, the underlying mechanism of the difference in vulnerability between adolescence and adulthood have not yet been elucidated. In this study, we attempted to elucidate the different effects of HFCS intake at different growth stages in rats: childhood and adolescence (postnatal day (PD) 21-60), young adulthood (PD60-100), and adulthood (PD100-140). Since alterations in hepatic glucocorticoid (GC) metabolism can cause diseases including insulin resistance, we focused on GC metabolizing enzymes such as 11 beta-hydroxysteroid dehydrogenase 1 and 2 (Hsd11b1 and Hsd11b2) and steroid 5 alpha-reductase 1 (Srd5a1). Western blotting showed an increase in Hsd11b1 expression and a decrease in Hsd11b2 expression in childhood and adolescence but not in adulthood. We also observed changes in Hsd11b1 and Hsd11b2 activities only in childhood and adolescence, consistent with the results of mRNA and protein expression analysis. The effect of high-fructose intake with regards to GC metabolism may therefore vary with developmental stage. This study provides insight into the adverse effects of fructose on GC metabolism in children in the context of increasing rates of HFCS consumption.

DNA methylation can be affected by numerous lifestyle factors, including diet. Tobacco smoking induces aryl hydrocarbon receptor repressor (AHRR) DNA hypomethylation, which increases the risk of lung and other cancers. However, no lifestyle habits that might increase or restore percentage of AHRR DNA methylation have been identified. We hypothesized that dietary intakes of vegetables/fruits and serum carotenoid concentrations are related to AHRR DNA methylation. A total of 813 individuals participated in this cross-sectional study. A food frequency questionnaire was used to assess dietary intake of vegetables and fruits. AHRR DNA methylation in peripheral blood mononuclear cells were measured using pyrosequencing method. In men, dietary fruit intake was significantly and positively associated with AHRR DNA methylation among current smokers (P for trend = .034). A significant positive association of serum provitamin A with AHRR DNA methylation was observed among current smokers (men: standardized β = 0.141 [0.045 to 0.237], women: standardized β = 0.570 [0.153 to 0.990]). However, compared with never smokers with low provitamin A concentrations, percentages of AHRR DNA methylation were much lower among current smokers, even those with high provitamin A concentrations (men: β = -19.1% [-33.8 to -19.8], women: β = -6.0% [-10.2 to -1.7]). Dietary intake of vegetables and fruits rich in provitamin A may increase percentage of AHRR DNA methylation in current smokers. However, although we found a beneficial effect of provitamin A on AHRR DNA methylation, this beneficial effect could not completely remove the effect of smoking on AHRR DNA demethylation.

BACKGROUND: Smoking is well known to be a major risk factor for cancer, and to decrease the levels of aryl hydrocarbon receptor repressor (AHRR) DNA methylation. AHRR is a key regulator for AHR signaling, which is involved in chemical metabolism and cancer development. Therefore, smoking-induced AHRR DNA hypomethylation may be associated with cancer development. However, it has not been reported that association between AHHR DNA methylation and cancer mortality in Asian population. Hence, we examined whether AHRR DNA methylation levels were associated with cancer mortality in a Japanese population. METHODS: This study was conducted with 812 participants (aged 38-80 years) who received a health check-up in 1990, and did not have a clinical histories. We followed up the participants until the end of 2019 (median: 27.8 years), and 100 participants died from cancer. The AHRR DNA methylation levels in peripheral blood mononuclear cells (PBMCs) were measured by the pyrosequencing method. We calculated the hazard ratio (HR) and 95% confidence interval (CI) for cancer mortality according to the baseline levels of AHRR DNA methylation. RESULTS: We found that AHRR DNA hypomethylation was associated with a higher risk of all cancer mortality, especially smoking related cancers and lung cancer. (all cancer: HR, 1.28, 95% CI, 1.09-1.51; smoking-related cancers: HR, 1.35, 95% CI, 1.12-1.62; lung cancer: HR, 1.68, 95% CI, 1.24-2.26). CONCLUSIONS: Smoking-induced AHRR DNA hypomethylation in PBMCs was associated with the risk of cancer mortality in Japanese population; therefore, hypomethylation of AHRR may be a useful biomarker of cancer mortality risk.

AIMS: This study aimed to analyze differences in sensitivity to hepatic lipid metabolism at different ages, through DNA methylation, using an experimental rat model of high-fructose corn syrup (HFCS) intake. MAIN METHODS: The experimental was divided into three periods: childhood and adolescence (postnatal day (PD) 21-60), young adulthood (PD61-100), and adulthood (PD101-140). Rats in the different age groups were assigned to receive either water (C: control group) or 20% HFCS solution (H: HFCS-fed group). We measured hepatic mRNA levels of peroxisome proliferator-activated receptor alpha (Ppara), carnitine palmitoyltransferase 1A (Cpt1a), fatty acid synthase (Fasn), and peroxisome proliferator-activated receptor-gamma coactivator 1 alpha (Pgc1a) using real-time PCR. Additionally, we examined the DNA methylation levels of Ppara, Cpt1a, Fasn, and Pgc1a using pyrosequencing. KEY FINDINGS: Gene expressions of Cpt1a and Ppara in childhood and adolescence were significantly lower in the H group than in the C group. Conversely, Fasn and Pgc1a expressions were significantly higher in the H group than in the C group. Additionally, there was hypermethylation of Cpt1a and Ppara and hypomethylation of Fasn and Pgc1a in the H groups of childhood and adolescence. However, only one gene expression and methylation change was observed in young adulthood and adulthood groups. We found that HFCS intake in rats had stronger lipid metabolic effects in childhood and adolescence than in other generations, and that its mechanism involved epigenetic regulation. SIGNIFICANCE: We anticipate that these research findings will be a breakthrough for elucidating the varying effects of growth stage in the future.