RNA m5C甲基化的研究进展

RNA 5-甲基胞嘧啶（m5C）甲基化修饰是主要的RNA转录后修饰之一。这种修饰存在于几乎所有类型RNA中,受甲基转移酶、去甲基转移酶及结合蛋白的调控,具有调节核mRNA输出及RNA可变剪切、增加RNA稳定性、调节蛋白质翻译及RNA-蛋白质互相作用、维持RNA正常结构等作用。其水平异常与肿瘤、神经系统缺陷、心血管系统疾病和异常分化等疾病密切相关。为全面了解RNA m5C的研究现状,本文将从RNA m5C的分布特点、调控机制、生物学作用及其与疾病的关系等方面进行综述。     

RNA m5C甲基化修饰在肿瘤中的研究进展

5-甲基胞嘧啶(5-methylcytosine,m5C)是RNA中重要的甲基化修饰之一,也是近年来的研究热点.随着甲基化测序技术的发展,在编码RNA及非编码RNA中均证实存在大量的m5C甲基化修饰.RNA m5C甲基化修饰受m5C甲基转移酶、去甲基化酶及m5C甲基化结合蛋白的调控.m5C甲基化修饰调节RNA的稳定性、...     

RNA甲基化修饰在肿瘤中的作用研究进展

目前已有150多种RNA甲基化修饰被确认为真核生物转录后调控标记.随着研究的不断深人,RNA甲基化修饰在癌症发生发展过程中的作用引起了越来越多的关注,但RNA甲基化修饰在肿瘤中的发生发展机制仍有待阐明.全文对RNA甲基化修饰类型、RNA甲基化修饰在肿瘤中的作用进行了总结,并对RNA甲基化修饰在肿瘤研究中所面临的挑战和未...     

m6A甲基化修饰在胃癌中的研究进展

N6-甲基腺苷（N6-methyladenosine,m6A）甲基化修饰是真核细胞mRNA最常见的一种表观遗传修饰方式。m6A甲基化修饰通过调控修饰mRNA,广泛参与细胞内RNA的许多生物学行为,从而影响疾病进展与肿瘤的发生。m6A RNA修饰相关因子在胃癌（gastric cancer,GC）中的异常表达,引发 m6A甲基化修饰失调,影响GC的增殖、转移与侵袭、凋亡和耐药等生物学过程。因此,本文就m6A RNA甲基化修饰在GC发生发展中的作用以及化疗耐药予以综述。      

RNA甲基化修饰在胶质母细胞瘤发生发展中的研究进展

胶质母细胞瘤（glioblastoma,GBM）是一种高度恶性的原发性中枢神经系统肿瘤,患者预后差。RNA甲基化修饰作为一种广泛研究的表观遗传机制,已被证明在肿瘤的发生和发展中发挥重要作用。该文旨在探讨各种RNA甲基化修饰方式在GBM发生发展中的研究进展,为探索更有效的治疗策略提供新方向。     

6A甲基化修饰在肿瘤中的作用

N6-甲基腺苷(m6A)修饰作为表观遗传学研究的一部分,是最常见的RNA修饰之一,近年来受到越来越多的关注。m6A甲基化修饰由甲基转移酶、去甲基化酶及阅读蛋白共同动态调节。大量研究表明,m6A甲基化修饰可以通过调节与癌症相关的生物学功能来影响癌症的发生发展。本文简要介绍了m6A甲基化修饰,并对m6A甲基化修饰在不同肿瘤中的作用进行综述。     

m6A甲基化在肿瘤中修饰非编码RNA的最新研究进展

非编码RNA(non-coding RNA,ncRNA)在细胞分化、血管生成、免疫应答、炎症反应以及肿瘤发生发展中具有重要作用.m6 A(N6-methyladenosine)甲基化是真核生物中最常见的RNA修饰方式之一,主要见于信使RNA(messenger RNA,mRNA).m6 A甲基化修饰主要有三种酶参与完成...     

DNA 甲基转移酶在肿瘤发病机制中的研究进展

DNA甲基化是表观遗传学的主要形式,而DNA甲基转移酶（ DNMTs）是DNA甲基化的主要调节酶,DNA甲基转移酶的激活参与了肿瘤的发生和发展过程,同时伴有肿瘤抑制基因的高甲基化沉默和低表达,是病人预后不良的标志;DNA甲基转移酶3b（ DNMT3b）的多态性及吸烟所致的DNMTs表达的改变是肿瘤发生的危险因素,靶向DNMTs治疗由于其细胞毒性小,是当前研究的一个热点。本文就DNA甲基转移酶在肿瘤发病机制中的作用做一综述。     

甲基化转移酶3在乳腺癌中的研究进展

甲基化转移酶3(METTL3)是N6-甲基腺嘌呤(m6A)最主要的甲基化酶, 通过影响甲基化水平、癌症相关基因mRNA稳定性、癌基因表达及癌细胞信号通路等多种调节机制在乳腺癌发生、发展中的发挥作用。文章对METTL3在乳腺癌中的调节机制进行整理和分析, 并总结METTL3在乳腺癌发生和发展中的最新研究进展。     

Genome-wide identification of m6A-associated functional SNPs as potential functional variants for thyroid cancer

m6A methylation has been demonstrated to be one of the most important epigenetic regulation mechanisms in cell differentiation and cancer development especially m6A derived diagnostic and prognostic biomarkers have been identified in the past several years. However, systemic investigation to the interaction between germline single-nucleotide polymorphisms (SNPs) and m6A has not been conducted yet. In this study, we collected previous identified significant thyroid cancer associated SNPs from UKB cohort (358 cases and 407,399 controls) and ICR cohort (3,001 patients and 287,550 controls) and thyroid eQTL (sample size = 574 from GTEx project) and m6A-SNP (N = 1,678,126) were applied to prioritize the candidate SNPs. Finally, five candidate genes (PLEKHA8, SMUG1, CDC123, RMI2, ACSM5) were identified to be thyroid cancer associated m6A-related genetic susceptibility. Loss and gain function studies of m6A writer proteins confirm that ACSM5 is regulated by m6A methylation of mRNA. Moreover, ACSM5 is downregulated in thyroid cancer and inversely correlated with PTC malignancy and patient survival. Together, our study highlight mRNA-seq and m6A-seq double analysis provided a novel approach to identify cancer biomarkers and understanding the heterogeneity of human cancers.     

FTO在胃癌组织中的表达降低及其对细胞系MGC-803功能的影响

胃癌的发生与环境、遗传和表观遗传因素密切相关。目前,RNA修饰是表观遗传领域的研究前沿和热点。随着分析化学和高通量测序技术的进步,解析RNA修饰的新技术和新方法不断涌现。大量研究已经证实RNA修饰参与多种疾病的发生和发展。最近研究发现m6A、m5C、ac4C等RNA修饰调控胃癌、肝癌、结直肠癌、白血病等多种肿瘤的恶性进程。本文就RNA修饰在胃癌发生发展中的研究现状和作用机制作系统综述,并讨论其在胃癌诊断和治疗方面的潜在价值。

     

siRNA敲减DNMT1表达对T-cadherin基因甲基化及结肠癌细胞生物学行为的影响

目的 肿瘤的发生、发展和侵袭转移是影响结肠癌治疗的重要原因,有研究发现DNA甲基化状态在肿瘤的发生、发展中起着重要作用,抑制T-cadherin表达可增强肿瘤细胞侵袭和迁移能力.本研究探讨siRNA敲减DNA甲基转移酶1(DNA methyl transferase 1,DNMT1)基因表达对结肠癌细胞T-cadherin基因甲基化及细胞生物学行为影响.方法 设计针对DNMT1的siRNA1、siRNA2和siRNA3重组质粒,分别转染HT-29、SW620和HCT116细胞系,采用实时荧光定量PCR检测DNMT1表达,以筛选敲减效率最高的DNMT1 siRNA和细胞系.用敲减效率最高的DNMT1 siRNA转染相应细胞系,采用甲基化特异性PCR检测T-cadherin甲基化水平,采用实时荧光定量PCR和蛋白印迹法检测T-cadherin表达.用敲减效率最高的DNMT1 siRNA转染相应细胞系,采用噻唑蓝比色法、流式细胞术、Transwell和细胞划痕实验检测细胞增殖、凋亡、侵袭和迁移情况,观察敲减DNMT1对细胞生物学行为的影响;同时设置T-cadherin shRNA重组质粒转染组,观察同时敲减DNMT1和T-cadherin对细胞生物学行为的影响.结果 DNMT1 siRNA1重组质粒对HT-29细胞系DNMT1的敲减效果最好.DNMT1 siRNA1转染HT-29细胞后,DNMT1组T-cadherin基因甲基化水平明显低于空质粒组和空白组,DNMT1组与空质粒组(F=314.182)和空白组(F=283.625)差异有统计学意义,均P<0.001.DNMT1组和联合组DNMT1 mRNA表达量(0.27±0.08)和蛋白表达量(0.41±0.12)显著低于空质粒组和空白组.其中mRNA表达,DNMT1组与空质粒组(F=544.581)和空白组(F=525.811)组差异有统计学意义,均P<0.001;联合组与空质粒组(F=507.501)和空白组(F=494.958)也差异有统计学意义,均P<0.001.蛋白表达量,DNMT1组与空质粒组(F=217.550)和空白组(F=275.469)差异有统计学意义,均P<0.001:联合组与空质粒组(F=321.707)和空白组(F=407.225)也差异有统计学意义,均P<0.001:而DNMT1组和联合组比较mRNA(F=0.002,P=0.965)和蛋白表达量(F=0.811,P=0.394)均差异无统计学意义.DNMT1组T-cadherin mRNA表达量(1.17±0.34)和蛋白表达量(1.38±0.54)显著高于联合组、空质粒组和空白组.其中mRNA表达,DNMT1组与联合组(F=433.103)、空质粒组(F=313.768)、空白组(F=372.118)差异有统计学意义,均P<0.001.对于蛋白表达量,DN-MT1组与联合组(F=89.315)、空质粒组(F=156.745)、空白组(F=196.702)差异有统计学意义,均P<0.001.而联合组与空质粒组(F=1.310,P=0.262;F=0.144,P=0.714)和空白组(F=3.713,P=0.064;F=0.038,P=0.850)的mRNA和蛋白表达量比较差异无统计学意义.与联合组、空质粒组和空白组比较,DNMT1组第24、36、48、72 h的A值显著减小,F组别=14.479,P<0.001;F时间=37.755,P<0.001.DNMT1组与联合组(F=1004.194,P<0.001)、空质粒组(F=1190.815,P<0.001)、空白组(F=781.018,P<0.001)比较细胞总凋亡率显著升高;DNMT1组穿膜细胞数目为(61.3±10.7)个,与联合组(F=86.730,P<0.001)、空质粒组(F=282.962,P<0.001)、空白组(F=152.538,P<0.001)比较显著减少.DNMT1组细胞迁移距离为(235.8±6.3)μm,与联合组(F=2535.55,P<0.001)、空质粒组(F=9767.233,P<0.001)、空白组(F=8420.830,P<0.001)比较显著减少.而联合组与空质粒组和空白组比较,A值、细胞总凋亡率、穿膜细胞数目和细胞迁移距离均差异无统计学意义,P>0.05.结论 DNMT1 siRNA1可有效敲减HT-29细胞DNMT1表达,逆转T-cadherin高甲基化状态并上调其表达.敲减DNMT1可明显抑制HT-29细胞增殖,促进其凋亡,降低其侵袭和迁移能力;而同时敲减T-cadherin能够逆转此种现象,说明敲减DNMT1引起的细胞生物学行为改变可能是通过T-cadherin来实现的.     

蛋白精氨酸甲基转移酶5在急性髓系白血病中的研究进展

急性髓系白血病(acute myeloid leukemia,AML)是一种常见的恶性血液肿瘤.表观遗传学修饰可以通过转录后甲基化等方式在AML中发挥关键作用.蛋白精氨酸甲基转移酶5(protein arginine methyl-transferase 5,PRMT5)是一种Ⅱ型蛋白精氨酸甲基转移酶,可通过催化作用将...     

Modes of action of the DNA methyltransferase inhibitors azacytidine and decitabine

The cytosine analogues 5-azacytosine (azacytidine) and 2'-deoxy-5-azacytidine (decitabine) are the currently most advanced drugs for epigenetic cancer therapies. These compounds function as DNA methyltransferase inhibitors and have shown substantial potency in reactivating epigenetically silenced tumor suppressor genes in vitro. However, it has been difficult to define the mode of action of these drugs in patients and it appears that clinical responses are influenced both by epigenetic alterations and by apoptosis induction. To maximize the clinical efficacy of azacytidine and decitabine it will be important to understand the molecular changes induced by these drugs. In this review, we examine the pharmacological properties of azanucleosides and their interactions with various cellular pathways. Because azacytidine and decitabine are prodrugs, an understanding of the cellular mechanisms mediating transmembrane transport and metabolic activation will be critically important for optimizing patient responses. We also discuss the mechanism of DNA methyltransferase inhibition and emphasize the need for the identification of predictive biomarkers for the further advancement of epigenetic therapies.     

Genomic gain of 5p15 leads to over-expression of Misu (NSUN2) in breast cancer

We have examined expression of the Myc target gene Misu (NSUN2) in breast cancer. There was extensive copy number gain, and increased mRNA and protein levels, of Misu in approximately one third of breast cancer cell lines and primary tumours examined, irrespective of tumour subtype. Genes on 5p15.31-33, where Misu is located, showed evolutionary synteny. siRNA-mediated knockdown of Misu reduced cell number in over half of the cell lines tested, irrespective of estrogen receptor status. We conclude that Misu is up-regulated in a substantial proportion of breast cancers and has therapeutic potential as a drug target.     

Construction and validation of an N6-methyladenosine-associated prognostic signature in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is among the most common types of cancer that threat the public health worldwide. N6-methyladenosine (m6A) RNA methylation is associated with cancer initiation and progression, and is dynamically regulated by m6A RNA methylation-associated genes. However, little is known about the expression status and the prognostic value of m6A-associated genes in HCC. The present study aimed to identify the expression profiling pattern and clinical significance of m6A-associated genes in HCC. Consensus clustering analysis was performed to identify the clusters of HCC with different clinical outcomes. A prognostic signature built by the least absolute shrinkage and selection operator Cox regression model was utilized to discover subtypes associated with different clinical outcomes of patients with HCC in the discovery cohort from The Cancer Genome Atlas. The differences between subgroups were characterized in terms of epigenetic dysregulation and somatic mutation frequencies. The International Cancer Genome Consortium cohort and two independent cohorts from the meta-Gene Expression Omnibus database were used for external validation. Most of the m6A-associated genes were upregulated and involved in the prognosis and malignancy of HCC. A four-gene prognostic signature revealed two HCC subtypes (namely, high- and low-risk group) that was associated with different clinical outcomes. Patients in the high-risk group were accompanied with increased epigenetic silencing and significant mutations in TP53 and FLG, while ALB was frequently mutated in the low-risk group. In conclusion, an m6A-based signature was constructed to predict the prognosis of patients with HCC, which may provide a tool for reliable prognosis assessment for clinicians, and aid clinical treatment decision-making.