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BACKGROUND@#Particulate matter (PM) < 2.5 μm (PM@*METHODS@#We obtained DNA methylation and exercise data of 496 participants (aged between 30 and 70 years) from the Taiwan Biobank (TWB) database. We also extracted PM@*RESULTS@#DLEC1 methylation and PM@*CONCLUSIONS@#We found significant positive associations between PM

Rol del consumo de alcohol y antioxidantes sobre la metilación global del ADN y cáncer / Role of alcohol consumption and antioxidants on global methylation of DNA and cancer

RESUMEN: El alcoholismo es una enfermedad crónica recidivante asociada a disfunción psicológica, social y física. El alcohol no sólo es una droga adictiva, también produce alteraciones en las actividades y funciones de múltiples sistemas y órganos. Actualmente, diversos estudios demuestran que el ambiente puede modular la expresión génica del ADN mediante mecanismos epigenéticos, sugiriendo de esta manera, que el consumo de alcohol es un factor que puede alterar los patrones epigenéticos y, por lo tanto, los niveles de expresión génica. La metilación del ADN es un proceso epigenético que participa en la regulación de la expresión génica, impidiendo la unión de factores de transcripción y propiciando la estructura cerrada de la cromatina. En este sentido, los cambios en la metilación del ADN se reconocen como una de las formas más comunes de alteración molecular en la dependencia al alcohol y los procesos neoplásicos humanos. El alcohol puede ser un factor importante en la iniciación del cáncer, aumentando la expresión de ciertos oncogenes o reprimiendo la capacidad de las células para reparar el ADN, lo que aumenta la probabilidad de que se produzcan mutaciones oncogénicas. Sin embargo, los mecanismos exactos de la patogénesis del cáncer ligada al consumo de alcohol aún permanecen sin ser dilucidados. Por lo anterior, el objetivo de la presente revisión fue describir los mecanismos de metilación del ADN y su relación con el consumo de alcohol y cáncer.

SUMMARY: Alcoholism is a chronic relapsing disease associated with psychological, social and physical dysfunction. Alcohol is not only an addictive substance, it also alters action and function of multiple systems and organs. Currently, several studies show that the environment can modulate gene expression of DNA by epigenetic mechanisms, thereby suggesting that alcohol consumption is a factor that can alter epigenetic patterns and therefore, the levels of gene expression. DNA methylation is an epigenetic process, that is a part of gene expression regulation preventing binding of transcription factors and encouraging the closed structure of chromatin. In this sense, changes in DNA methylation are recognized as one of the most common forms of molecular alteration in alcohol dependence and human neoplastic processes. Alcohol can be an important factor in activating the cancer by increasing the expression of certain oncogenes or repressing the ability of cells to repair DNA, which increases the likelihood of oncogenic mutations. However, the exact mechanisms of the pathogenesis of cancer linked to alcohol consumption remain unclear. Therefore, the objective of this review was to describe the mechanisms of DNA methylation and its relation to alcohol consumption and cancer.

Epigenetic modulation as a therapeutic approach for pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a rare but progressive and currently incurable disease, which is characterized by vascular remodeling in association with muscularization of the arterioles, medial thickening and plexiform lesion formation. Despite our advanced understanding of the pathogenesis of PAH and the recent therapeutic advances, PAH still remains a fatal disease. In addition, the susceptibility to PAH has not yet been adequately explained. Much evidence points to the involvement of epigenetic changes in the pathogenesis of a number of human diseases including cancer, peripheral hypertension and asthma. The knowledge gained from the epigenetic study of various human diseases can also be applied to PAH. Thus, the pursuit of novel therapeutic targets via understanding the epigenetic alterations involved in the pathogenesis of PAH, such as DNA methylation, histone modification and microRNA, might be an attractive therapeutic avenue for the development of a novel and more effective treatment. This review provides a general overview of the current advances in epigenetics associated with PAH, and discusses the potential for improved treatment through understanding the role of epigenetics in the development of PAH.

Stability of XIST repression in relation to genomic imprinting following global genome demethylation in a human cell line

DNA methylation is essential in X chromosome inactivation and genomic imprinting, maintaining repression of XIST in the active X chromosome and monoallelic repression of imprinted genes. Disruption of the DNA methyltransferase genes DNMT1 and DNMT3B in the HCT116 cell line (DKO cells) leads to global DNA hypomethylation and biallelic expression of the imprinted gene IGF2 but does not lead to reactivation of XIST expression, suggesting that XIST repression is due to a more stable epigenetic mark than imprinting. To test this hypothesis, we induced acute hypomethylation in HCT116 cells by 5-aza-2′-deoxycytidine (5-aza-CdR) treatment (HCT116-5-aza-CdR) and compared that to DKO cells, evaluating DNA methylation by microarray and monitoring the expression of XIST and imprinted genes IGF2, H19, and PEG10. Whereas imprinted genes showed biallelic expression in HCT116-5-aza-CdR and DKO cells, the XIST locus was hypomethylated and weakly expressed only under acute hypomethylation conditions, indicating the importance of XIST repression in the active X to cell survival. Given that DNMT3A is the only active DNMT in DKO cells, it may be responsible for ensuring the repression of XIST in those cells. Taken together, our data suggest that XIST repression is more tightly controlled than genomic imprinting and, at least in part, is due to DNMT3A.

DNA methylation regulates expression of VEGF-C, and S-adenosylmethionine is effective for VEGF-C methylation and for inhibiting cancer growth

DNA hypomethylation may activate oncogene transcription, thus promoting carcinogenesis and tumor development. S-adenosylmethionine (SAM) is a methyl donor in numerous methylation reactions and acts as an inhibitor of intracellular demethylase activity, which results in hypermethylation of DNA. The main objectives of this study were to determine whether DNA hypomethylation correlated with vascular endothelial growth factor-C (VEGF-C) expression, and the effect of SAM on VEGF-C methylation and gastric cancer growth inhibition. VEGF-C expression was assayed by Western blotting and RT-qPCR in gastric cancer cells, and by immunohistochemistry in tumor xenografts. VEGF-C methylation was assayed by bisulfite DNA sequencing. The effect of SAM on cell apoptosis was assayed by flow cytometry analyses and its effect on cancer growth was assessed in nude mice. The VEGF-C promoters of MGC-803, BGC-823, and SGC-7901 gastric cancer cells, which normally express VEGF-C, were nearly unmethylated. After SAM treatment, the VEGF-C promoters in these cells were highly methylated and VEGF-C expression was downregulated. SAM also significantly inhibited tumor growth in vitro and in vivo. DNA methylation regulates expression of VEGF-C. SAM can effectively induce VEGF-C methylation, reduce the expression of VEGF-C, and inhibit tumor growth. SAM has potential as a drug therapy to silence oncogenes and block the progression of gastric cancer.

Improved Therapeutic Effect against Leukemia by a Combination of the Histone Methyltransferase Inhibitor Chaetocin and the Histone Deacetylase Inhibitor Trichostatin A

SUV39H1 is a histone 3 lysine 9 (H3K9)-specific methyltransferase that is important for heterochromatin formation and the regulation of gene expression. Chaetocin specifically inhibits SUV39H1, resulted in H3K9 methylation reduction as well as reactivation of silenced genes in cancer cells. Histone deacetylase (HDAC) inhibitors inhibit deacetylases and accumulate high levels of acetylation lead to cell cycle arrest and apoptosis. In this study, we demonstrated that treatment with chaetocin enhanced apoptosis in human leukemia HL60, KG1, Kasumi, K562, and THP1 cells. In addition, chaetocin induced the expression of cyclin-dependent kinase inhibitor 2B (p15), E-cadherin (CDH1) and frizzled family receptor 9 (FZD9) through depletion of SUV39H1 and reduced H3K9 methylation in their promoters. Co-treatment with chaetocin and HDAC inhibitor trichostatin A (TSA) dramatically increased apoptosis and produced greater activation of genes. Furthermore, this combined treatment significantly increased loss of SUV39H1 and reduced histone H3K9 trimethylation responses accompanied by increased acetylation. Importantly, co-treatment with chaetocin and TSA produced potent antileukemic effects in leukemia cells derived from patients. These in vitro findings suggest that combination therapy with SUV39H1 and HDAC inhibitors may be of potential value in the treatment of leukemia.

Efficacy of the dietary histone deacetylase inhibitor butyrate alone or in combination with vitamin A against proliferation of MCF-7 human breast cancer cells

The combined treatment with histone deacetylase inhibitors (HDACi) and retinoids has been suggested as a potential epigenetic strategy for the control of cancer. In the present study, we investigated the effects of treatment with butyrate, a dietary HDACi, combined with vitamin A on MCF-7 human breast cancer cells. Cell proliferation was evaluated by the crystal violet staining method. MCF-7 cells were plated at 5 x 10(4) cells/mL and treated with butyrate (1 mM) alone or combined with vitamin A (10 µM) for 24 to 120 h. Cell proliferation inhibition was 34, 10 and 46% following treatment with butyrate, vitamin A and their combination, respectively, suggesting that vitamin A potentiated the inhibitory activities of butyrate. Furthermore, exposure to this short-chain fatty acid increased the level of histone H3K9 acetylation by 9.5-fold (Western blot), but not of H4K16, and increased the expression levels of p21WAF1 by 2.7-fold (Western blot) and of RARβ by 2.0-fold (quantitative real-time PCR). Our data show that RARβ may represent a molecular target for butyrate in breast cancer cells. Due to its effectiveness as a dietary HDACi, butyrate should be considered for use in combinatorial strategies with more active retinoids, especially in breast cancers in which RARβ is epigenetically altered.

DNA Methylation of RUNX3 in Papillary Thyroid Cancer

BACKGROUND/AIMS: The relationship between Runt-related transcription factor 3 (RUNX3) gene inactivation and various solid tumors has been reported; however, little information is available about RUNX3 in thyroid cancers. METHODS: We evaluated the DNA methylation of RUNX3 in 13 papillary thyroid cancer tissues and four thyroid cancer cell lines. Additionally, using reverse transcriptase-polymerase chain reaction, we analyzed RUNX3 gene expression in several thyroid cancer cell lines after treating with the demethylating agent 5-aza-2'-deoxycytidine (DAC). RESULTS: RUNX3 was hypermethylated in many thyroid cancer cell lines and in 10 of the 12 papillary thyroid cancer tissues. Treatment with DAC increased the expression of RUNX3 in some thyroid cancer cell lines. CONCLUSIONS: We suggest that RUNX3 is associated with thyroid carcinogenesis, and RUNX3 methylation is a potentially useful diagnostic marker for papillary thyroid cancer.

Pharmacological Unmasking Microarray Approach-Based Discovery of Novel DNA Methylation Markers for Hepatocellular Carcinoma

DNA methylation is one of the main epigenetic mechanisms and hypermethylation of CpG islands at tumor suppressor genes switches off these genes. To find novel DNA methylation markers in hepatocellular carcinoma (HCC), we performed pharmacological unmasking (treatment with 5-aza-2'-deoxycytidine or trichostatin A) followed by microarray analysis in HCC cell lines. Of the 239 promoter CpG island loci hypermethylated in HCC cell lines (as revealed by methylation-specific PCR), 221 loci were found to be hypermethylated in HCC or nonneoplastic liver tissues. Thirty-three loci showed a 20% higher methylation frequency in tumors than in adjacent nonneoplastic tissues. Correlation of individual cancer-related methylation markers with clinicopathological features of HCC patients (n = 95) revealed that the number of hypermethylated genes in HCC tumors was higher in older than in younger patients. Univariate and multivariate survival analysis revealed that the HIST1H2AE methylation status is closely correlated with the patient's overall survival (P = 0.022 and P = 0.010, respectively). In conclusion, we identified 221 novel DNA methylation markers for HCC. One promising prognostic marker, HIST1H2AE, should be further validated in the prognostication of HCC patients.

DNA Methylation Changes Following 5-azacitidine Treatment in Patients with Myelodysplastic Syndrome

DNA methyltransferase inhibitor, 5-azacitidine (AC) is effective in myelodysplastic syndromes (MDS) and can induce re-expression in cancer. We analyzed the methylation of 25 tumor suppressor genes in AC-treated MDS. Hypermethylation of CDKN2B, FHIT, ESR1, and IGSF4 gene was detected in 9/44 patients. In concordance with the clinical response, a lack of or decreased methylation in 4 patients with hematologic improvements and persistent methylation in 4 others with no response was observed. The mRNA expression of CDKN2B, IGSF4, and ESR1 was significantly reduced in MDS. Our results suggest that methylation changes contribute to disease pathogenesis and may serve as marker to monitor the efficacy of treatments.

Epigenetic targets in the diagnosis and treatment of prostate cancer

Prostate cancer (PC) is one of leading cause of cancer related deaths in men. Various aspects of cancer epigenetics are rapidly evolving and the role of 2 major epigenetic changes including DNA methylation and histone modifications in prostate cancer is being studied widely. The epigenetic changes are early event in the cancer development and are reversible. Novel epigenetic markers are being studied, which have the potential as sensitive diagnostic and prognostic marker. Variety of drugs targeting epigenetic changes are being studied, which can be effective individually or in combination with other conventional drugs in PC treatment. In this review, we discuss epigenetic changes associated with PC and their potential diagnostic and therapeutic applications including future areas of research.

High frequency of p 16 promoter methylation in non-small cell lung carcinomas from Chile

The inactivation of tumour suppressor genes by aberrant methylation of promoter regions has been described as a frequent event in neoplasia development, including lung cancer. The p16 gene is a tumour suppressor gene involved in the regulation of cell cycle progression that has been reported to be inactivated by promoter methylation in lung carcinomas at variable frequencies around the world in a smoking habit dependent manner. The purpose of this study was to investigate the methylation status of the promoter region of the p16 gene in 74 non-small cell lung carcinomas from Chile. The frequency of p16 gene inactivation by promoter methylation was determined as 79.7 percent (59/74). When we considered histological type, we observed that p16 promoter methylation was significantly higher in squamous cell carcinomas (30/33, 91 percent) compared with adenocarcinomas (21/30, 70 percent) (p=0.029). In addition, no association between p16 promoter methylation and gender, age or smoking habit was found (p=0.202, 0.202 and 0.147 respectively). Our results suggest that p16 promoter hypermethylation is a very frequent event in non-small cell lung carcinomas from Chile and could be smoking habit-independent.

Differential promoter methylation may be a key molecular mechanism in regulating BubR1 expression in cancer cells

The BubR1 mitotic-checkpoint protein monitors proper attachment of microtubules to kinetochores, and links regulation of chromosome-spindle attachment to mitotic-checkpoint signaling. Thus, disruption of BubR1 activity results in a loss of checkpoint control, chromosomal instability caused by a premature anaphase, and/or the early onset of tumorigenesis. The mechanisms by which deregulation and/or abnormalities of BubR1 expression operate, however, remain to be elucidated. In this study, we demonstrate that levels of BubR1 expression are significantly increased by demethylation. Bisulfite sequencing analysis revealed that the methylation status of two CpG sites in the essential BubR1 promoter appear to be associated with BubR1 expression levels. Associations of MBD2 and HDAC1 with the BubR1 promoter were significantly relieved by addition of 5-aza-2'-deoxycytidine, an irreversible DNA methyltransferase inhibitor. However, genomic DNA isolated from 31 patients with colorectal carcinomas exhibited a +84A/G polymorphic change in approximately 60% of patients, but this polymorphism had no effect on promoter activity. Our findings indicate that differential regulation of BubR1 expression is associated with changes in BubR1 promoter hypermethylation patterns, but not with promoter polymorphisms, thus providing a novel insight into the molecular regulation of BubR1 expression in human cancer cells.