Accumulation of aberrant DNA methylation during colorectal cancer development

Despite the recent advances in the therapeutic modalities,colorectal cancer(CRC)remains to be one of the most common causes of cancer-related death.CRC arises through accumulation of multiple genetic and epigenetic alterations that transform normal colonic epithelium into adenocarcinomas.Among crucial roles of epigenetic alterations,gene silencing by aberrant DNA methylation of promoter regions is one of the most important epigenetic mechanisms.Recent comprehensive methylation analyses on genome-wide scale revealed that sporadic CRC can be classified into distinct epigenotypes.Each epigenotype cooperates with specific genetic alterations,suggesting that they represent different molecular carcinogenic pathways.Precursor lesions of CRC,such as conventional and serrated adenomas,already show similar methylation accumulation to CRC,and can therefore be classified into those epigenotypes of CRC.In addition,specific DNA methylation already occurs in the normal colonic mucosa,which might be utilized for prediction of the personal CRC risk.DNA methylation is suggested to occur at an earlier stage than carcinoma formation,and may predict the molecular basis for future development of CRC.Here,we review DNA methylation and CRC classification,and discuss the possible clinical usefulness of DNA methylation as biomarkers for the diagnosis,prediction of the prognosis and the response to therapy of CRC.     

Epigenetic aberrant methylation of tumor suppressor genes in small cell lung cancer

Small cell lung cancer (SCLC), a special type of lung cancer, is reputed to carry a poor prognosis. The morbidity of SCLC is increasing in China and other countries. A variety of DNA alterations associated with non-small cell lung cancer (NSCLC) have been described. However, genetic and epigenetic changes of SCLC are not well established. Few studies have demonstrated that epigenetic silencing of key tumor suppressor genes (TSGs) is pivotal to initiation and development of SCLC. Recently, promoter methylation of many TSGs have been identified in SCLC. These novel TSGs are potential tumor biomarkers for early diagnosis and prognostic prediction. Moreover, epigenetic promoter methylation of TSGs could be a target of intervention with a wide prospect of clinical application. This review summarizes recent studies on promoter methylation of TSGs in SCLC and aims to provide better understanding of the promoter methylation in tumorigenesis and progression of SCLC.KEY WORDS : Small cell lung cancer (SCLC), tumor suppressor gene (TSG), promotor methylation, hypermethylation     

表观遗传学变化在胃癌诊断和预后中的应用

胃癌的恶性程度高且预后较差,目前随着对胃癌基础研究的不断深入,表观遗传学改变在胃癌发生发展中的重要作用逐渐被人们认识,特别是基因启动子区域的DNA甲基化被认为是肿瘤中普遍发生的分子改变,本文主要论述了胃癌相关基因甲基化状态的研究进展,目的在于探讨表观遗传学在胃癌早期诊断及预后中的意义。     

Reversing Epigenetic Alterations Caused by Alcohol: A Promising Therapeutic Direction for Alcoholic Liver Disease

Alcoholic liver disease (ALD), a liver function disorder caused by excessive alcohol intake, is a serious threat to global public health and social development. Toxic metabolites and reactive oxygen species produced during the metabolism of alcohol can alter the epigenetic state including DNA methylation, histone modifications, and expression of microRNAs. Epigenetic alterations can conversely involve various signaling pathways, which could contribute to the initiation and progression of ALD. To elucidate the relationship between epigenetic alterations and alcohol damage not only reinforces our understanding on pathogenesis of ALD, but also provides novel targets for clinical diagnosis, treatment, and drug research of ALD. In this review, we have summarized the research progress of epigenetic alterations and related mechanisms caused by alcohol in the pathogenesis of ALD. Considering the invertibility of epigenetic alterations, treatment of ALD through epigenetic modification with common less harmful compounds is also related.     

Advances in understanding and treating liver diseases during pregnancy:A review

Liver disease in pregnancy is rare but pregnancyrelated liver diseases may cause threat to fetal and maternal survival.It includes pre-eclampsia;eclampsia;haemolysis,elevated liver enzymes,and low platelets syndrome;acute fatty liver of pregnancy;hyperemesis gravidarum;and intrahepatic cholestasis of pregnancy.Recent basic researches have shown the various etiologies involved in this disease entity.With these advances,rapid diagnosis is essential for severe cases since the decision of immediate delivery is important for maternal and fetal survival.The other therapeutic options have also been shown in recent reports based on the clinical trials and cooperation and information sharing between hepatologist and gynecologist is important for timely therapeutic intervention.Therefore,correct understandings of diseases and differential diagnosis from the pre-existing and co-incidental liver diseases during the pregnancy will help to achieve better prognosis.Therefore,here we review and summarized recent advances in understanding the etiologies,clinical courses and management of liver disease in pregnancy.This information will contribute to physicians for diagnosis of disease and optimum management of patients.     

DNA甲基化在结直肠癌诊疗中的应用前景

目前认为结直肠癌的发生是在环境因素的作用下通过遗传学和表观遗传学的累积性改变所致。表观遗传学修饰,特别是基因启动子区域的DNA甲基化,被认为是肿瘤中普遍发生的分子改变。因此可通过检测基因的异常甲基化等表观遗传学改变对结直肠癌进行预防、早期诊断、临床治疗及预后评价。本文论述了结直肠癌相关基因甲基化状态的研究进展以及表观遗传学的临床应用,目的在于探讨表观遗传学在结直肠癌早期诊断及治疗中的意义。     

Non-invasive methods for liver fibrosis prediction in hemochromatosis: One step beyond

Advances in recent years in the understanding of, and the genetic diagnosis of hereditary hemochromatosis (HH) have changed the approach to iron overload hereditary diseases. The ability to use a radiologic tool (MRI) that accurately provides liver iron concentration determination, and the presence of non-invasive serologic markers for fibrosis prediction (serum ferritin, platelet count, transaminases, etc), have diminished the need for liver biopsy for diagnosis and prognosis of this disease. Consequently, the role of liver biopsy in iron metabolism disorders is changing. Furthermore, the irruption of transient elastography to assess liver stiffness, and, more recently, the ability to determine liver fibrosis by means of MRI elastography will change this role even more, with a potential drastic decline in hepatic biopsies in years to come. This review will provide a brief summary of the different non-invasive methods available nowadays for diagnosis and prognosis in HH, and point out potential new techniques that could come about in the next years for fibrosis prediction, thus avoiding the need for liver biopsy in a greater number of patients. It is possible that liver biopsy will remain useful for the diagnosis of associated diseases, where other non-invasive means are not possible, or for those rare cases displaying discrepancies between radiological and biochemical markers.     

Methylation-mediated gene silencing as biomarkers of gastric cancer:a review

Despite a decline in the overall incidence of gastric cancer(GC),the disease remains the second most common cause of cancer-related death worldwide and is thus a significant global health problem.The best means of improving the survival of GC patients is to screen for and treat early lesions.However,GC is often diagnosed at an advanced stage and is associated with a poor prognosis.Current diagnostic and therapeutic strategies have not been successful in decreasing the global burden of the disease;therefore,the identification of reliable biomarkers for an early diagnosis,predictive markers of recurrence and survival and markers of drug sensitivity and/or resistance is urgently needed.The initiation and progression of GC depends not only on genetic alterations but also epigenetic changes,such as DNA methylation and histone modification.Aberrant DNA methylation is the most well-defined epigenetic change in human cancers and is associated with inappropriate gene silencing.Therefore,an increasing number of genes methylated at the promoter region have been targeted as possible biomarkers for different purposes,including early detection,classification,the assessment of the tumor prognosis,the development of therapeutic strategies and patient follow-up.This review article summarizes the current understanding and recent evidence regarding DNA methylation markers in GC with a focus on the clinical potential of these markers.     

动脉粥样硬化的表观遗传调控

表观遗传调控指的是在DNA序列不变的情况下基因表达发生的可遗传性改变。目前,已知的表观遗传调控的主要机制包括DNA甲基化、组蛋白修饰和非编码RNA。大量研究证实,在心血管疾病、肿瘤和自身免疫性疾病等方面表观遗传调控发挥着重要作用。近年来,越来越多的研究表明,表观遗传调控在动脉粥样硬化的疾病病程中发挥着重要作用。本文将围绕DNA甲基化、组蛋白修饰和非编码RNA这三种主要的表观遗传调控对血管平滑肌细胞的调节来探讨表观遗传调控在动脉粥样硬化进程中的重要作用。     

The role of epigenetic alterations in pancreatic cancer

The past several years have witnessed an explosive increase in our knowledge about epigenetic features in human cancers. It has become apparent that pancreatic cancer is an epigenetic disease, as it is a genetic disease, characterized by widespread and profound alterations in DNA methylation. The introduction of genome-wide screening techniques has accelerated the discovery of a growing list of genes with abnormal methylation patterns in pancreatic cancer, and some of these epigenetic events play a role in the neoplastic process. The detection and quantification of DNA methylation alterations in pancreatic juice is likely a promising tool for the diagnosis of pancreatic cancer. The potential reversibility of epigenetic changes in genes involved in tumor progression makes them attractive therapeutic targets, but the efficacy of epigenetic therapies in pancreatic cancer, such as the use of DNA methylation inhibitors, remains undetermined. In this review, we briefly summarize recent research findings in the field of pancreatic cancer epigenetics and discuss their biological and clinical implications.     

Epigenetic stochasticity,nuclear structure and cancer: the implications for medicine

The aim of this review is to summarize an evolution of thinking about the epigenetic basis of human cancer, from the earliest studies of altered DNA methylation in cancer to the modern comprehensive epigenomic era. Converging data from epigenetic studies of primary cancers and from experimental studies of chromatin in development and epithelial–mesenchymal transition suggest a role for epigenetic stochasticity as a driving force of cancer, with Darwinian selection of tumour cells at the expense of the host. This increased epigenetic stochasticity appears to be mediated by large‐scale changes in DNA methylation and chromatin in domains associated with the nuclear lamina. The implications for diagnosis include the potential to identify stochastically disrupted progenitor cells years before cancer develops, and to target drugs to epigenetic drivers of gene expression instability rather than to mean effects per se.     

人工智能技术赋能超声影像在肝脏疾病的精准诊疗

肝脏疾病是影响人类健康的主要问题之一。超声在肝脏弥漫性和局灶性病变诊疗中发挥着重要作用,但传统超声评估存在主观性强且提供信息有限的问题。人工智能技术因能弥补传统超声的不足而被广泛应用于肝病超声领域,其在肝脏疾病诊断、疗效评估和预后预测等领域的应用取得了显著进展。本文对近年来国内外基于超声影像的人工智能技术在肝脏弥漫性和局灶性病变诊疗中的研究进展进行综述。     

The growing role of gene methylation on endocrine function

DNA methylation is the best studied epigenetic factor, playing a key role in producing stable changes in gene expression, thus defining cell identity and function and adapting cells to environmental changes. DNA methylation has also been recently shown to mediate cell responses to physiological endocrine signals. Moreover, alterations of the normal DNA methylation pattern can also contribute to the development of endocrine and metabolic diseases and can explain the relationship between an individual's genetic background, the environment, and disease. It should be remarked that although DNA methylation and demethylation are active processes, epigenetic changes produced during development can impact adult processes, establishing the idea that endocrine function can be persistently affected by events occurring in early life. Given the complexity of the endocrine system, both genetic and epigenetic processes, including DNA methylation, must be involved in its proper development and functioning. In this study, we summarize the recent knowledge in the field of DNA methylation and endocrinology. Given that DNA methylation can be involved in a number of endocrine and metabolic disorders, understanding and manipulating this modification opens a new door for preventing and treating endocrine diseases.     

Epigenetics and Peripheral Artery Disease

The term epigenetics is usually used to describe inheritable changes in gene function which do not involve changes in the DNA sequence. These typically include non-coding RNAs, DNA methylation and histone modifications. Smoking and older age are recognised risk factors for peripheral artery diseases, such as occlusive lower limb artery disease and abdominal aortic aneurysm, and have been implicated in promoting epigenetic changes. This brief review describes studies that have associated epigenetic factors with peripheral artery diseases and investigations which have examined the effect of epigenetic modifications on the outcome of peripheral artery diseases in mouse models. Investigations have largely focused on microRNAs and have identified a number of circulating microRNAs associated with human peripheral artery diseases. Upregulating or antagonising a number of microRNAs has also been reported to limit aortic aneurysm development and hind limb ischemia in mouse models. The importance of DNA methylation and histone modifications in peripheral artery disease has been relatively little studied. Whether circulating microRNAs can be used to assist identification of patients with peripheral artery diseases and be modified in order to improve the outcome of peripheral artery disease will require further investigation.     

循环肿瘤细胞及游离DNA甲基化在肝细胞癌患者中的研究进展

随着对肿瘤认识的不断深入,人们发现在原发肿瘤形成和生长的早期阶段,肿瘤细胞即可以脱离原发肿瘤组织释放到外周血形成循环肿瘤细胞,同样在肿瘤形成的早期阶段就会出现肿瘤细胞的坏死和凋亡,这些凋亡或坏死的肿瘤细胞也可以释放其DNA入外周血形成血浆或血清游离的DNA,因此对肿瘤患者循环肿瘤细胞及游离DNA的分析被认为是实时的"液相活检",肿瘤患者中的循环肿瘤细胞具有非常强的异质性,我们可以根据其物理和生物学性质采用不同的技术对其进行富集和检测;可以借助现代分子生物学手段对循环游离DNA进行提取,并对其遗传学和表观遗传学的异常改变进行分析,这可为肿瘤的早期诊断、疗效评估、复发监测及预后判断提供重要的信息.本文结合本课题组的研究重点,就循环肿瘤细胞及游离DNA及其甲基化在肝细胞癌患者的研究进行综述.     

Epigenetic regulation of insulin action and secretion – role in the pathogenesis of type 2 diabetes

The prevalence of type 2 diabetes (T2D) is rapidly increasing worldwide. Obesity, physical inactivity and ageing increase the risk of T2D. Epigenetic modifications can change due to environmental exposures and may thereby predispose to disease. This review aims at summarizing recent advances in epigenetics related to T2D, with a special focus on impaired insulin action and secretion in humans. There will be an emphasis on analyses in human tissues; both from T2D case‐control cohorts and intervention studies. Current data support an important role for epigenetics in the pathogenesis of T2D. Numerous studies have found differential DNA methylation and gene expression in skeletal muscle, adipose tissue, the liver and pancreatic islets from subjects with T2D compared with nondiabetic controls. For example, PDX1 has increased DNA methylation and decreased expression in pancreatic islets from patients with T2D compared with nondiabetic controls. Nongenetic risk factors for T2D such as ageing, unhealthy diets and physical activity do also impact the epigenome in human tissues. Interestingly, physical activity altered DNA methylation of candidate genes for T2D such as THADA in muscle and FTO, KCNQ1 and TCF7L2 in adipose tissue. There is also a strong interaction between genetic and epigenetic factors that together seem to affect T2D. mQTL studies in human adipose tissue and pancreatic islets showed that SNPs associated with DNA methylation levels in numerous sites. Several of these SNPs are also associated with T2D. Recent data also support that DNA methylation of some sites in blood may be developed into biomarkers that predict T2D since methylation of, for example TXNIP, ABCG1 and SREBF1 associated with future T2D. Future studies should use this information for development of new therapies and biomarkers and thereby improve prediction, prevention and treatment of T2D and its complications.     

MicroRNA和DNA甲基化在肺癌诊断中的研究进展

小分子核糖核酸（MicroRNA）作为肺癌早期的一种新的生物标志物,为肿癌的诊断提供了一种新的方法。MicroRNA在肿瘤发生发展过程中发挥癌基因和抑癌基因的作用。MicroRNA与肺癌增殖、侵袭、治疗、预后和复发有着密切关系。DNA甲基化是目前最主要的一种表观遗传修饰形式,抑癌基因的高甲基化使DNA染色质构象发生改变导致转录失活,引起肿瘤发生。DNA甲基化和MicroRNA在功能上相互调控,对肺癌的发生、发展同样重要。     

Epigenetics and Development of Food Allergy (FA) in Early Childhood

This review aims to highlight the latest advance on epigenetics in the development of food allergy (FA) and to offer future perspectives. FA, a condition caused by an immunoglobulin (Ig) E-mediated hypersensitivity reaction to food, has emerged as a major clinical and public health problem worldwide in light of its increasing prevalence, potential fatality, and significant medical and economic impact. Current evidence supports that epigenetic mechanisms are involved in immune regulation and that the epigenome may represent a key “missing piece” of the etiological puzzle for FA. There are a growing number of population-based epigenetic studies on allergy-related phenotypes, mostly focused on DNA methylation. Previous studies mostly applied candidate-gene approaches and have demonstrated that epigenetic marks are associated with multiple allergic diseases and/or with early-life exposures relevant to allergy development (such as early-life smoking exposure, air pollution, farming environment, and dietary fat). Rapid technological advancements have made unbiased genome-wide DNA methylation studies highly feasible, although there are substantial challenge in study design, data analyses, and interpretation of findings. In conclusion, epigenetics represents both an important knowledge gap and a promising research area for FA. Due to the early onset of FA, epigenetic studies of FA in prospective birth cohorts have the potential to better understand gene-environment interactions and underlying biological mechanisms in FA during critical developmental windows (preconception, in utero, and early childhood) and may lead to new paradigms in the diagnosis, prevention, and management of FA and provide novel targets for future drug discovery and therapies for FA.