肺癌mdig基因对H3k9me3的去甲基化作用

目的:观察肺癌mdig基因对组蛋白H3及H4部分位点赖氨酸残基的甲基化状态的作用。方法:用过表达和沉默mdig质粒转染人类肺腺癌细胞系A549细胞建立稳定转染细胞系,通过免疫蛋白印迹法和免疫荧光法检测mdig对H3k4me3、H3k4me2、H3k4me1,H3k9me3、H3k9me2、H3k9me1,H3k27me3、H3k27me2、H3k27me1,H3k36me3、H3k36me2、H3k36me1及H4k20me3的甲基化状态的影响。结果:免疫蛋白印迹法显示过表达mdig引起H3k9me3的表达减弱,沉默mdig引起H3k9me3的表达增强,组蛋白H3上的4、27、36和组蛋白H4上的20位点上的赖氨酸残基甲基化状态未见明显变化。免疫荧光法显示沉默mdig引起H3k9me3的荧光表达增强,与免疫蛋白印迹法结果一致。结论:肺癌mdig基因对H3k9me3有去甲基化的作用,未见其对其他赖氨酸位点的去甲基化作用。     

萝卜硫素对小鼠乳腺癌4T1细胞上皮-间质转化、增殖和迁移的影响研究

背景与目的:组蛋白去乙酰化酶5(histone deacetylase 5,HDAC5)在乳腺癌组织中异常高表达,其与赖氨酸特异性去甲基化酶1(lysine specific demethylase,LSD1)协同促进乳腺癌细胞增殖和迁移.通过萝卜硫素(sulforaphane,SFN)下调HDAC5表达,观察其对小鼠...     

LSD1在肿瘤中的研究进展及其抑制剂的开发现状

在肿瘤的发生、发展过程中,遗传物质的异常改变发挥了重要作用,但随着表观遗传学的出现,改变了人类对遗传信息的认知,表观遗传学逐渐成为肿瘤研究领域中的热点。组蛋白去甲基化酶1(LSD1)是第1个被发现的组蛋白去甲基化酶,依赖于FAD的单胺氧化酶,可以催化组蛋白赖氨酸H3K4和H3K9去甲基化,启动或抑制基因的转录。目前研究证实,LSD1在多种肿瘤中高表达并与肿瘤的发生及预后密切相关。LSD1对肿瘤的增殖、侵袭和转移起重要的调控作用,因此逐渐成为潜在的抗肿瘤靶点。本文将对LSD1在肿瘤领域的研究进展及其抑制剂在肿瘤中的应用作一综述。     

LncRNA HOTAIR与肺癌相关性的研究进展

摘 要：长链非编码RNA（lncRNAs）控制着几乎所有的生物过程,lncRNA HOX转录反义RNA (HOTAIR)通过其相关蛋白来抑制基因表达。HOTAIR增加肺癌细胞的增殖、侵袭、转移及耐药能力,其在肺癌中的高表达与肺癌的转移及不良预后相关。全文回顾长链非编码RNA HOTAIR介导的肺癌侵袭性表现的分子机制,并且讨论了HOTAIR在肺癌诊断和治疗方面的潜力。     

zeste基因增强子同源物2与卵巢癌关系的研究进展

zeste基因增强子同源物2(EZH2)通常在实体瘤中过表达,因此成为肿瘤的治疗靶点,其经典促肿瘤机制是催化组蛋白3上赖氨酸27的三甲基化,形成H3K27me3,从而诱导靶基因的转录抑制。EZH2已被证明在肿瘤细胞增殖、侵袭、转移、血管生成和化疗耐药过程中发挥关键作用。近年来,关于EZH2的研究不断增多,其介导细胞代谢新途径、与微小RNA(miRNA)和长链非编码RNA(lncRNA)的相互作用、诱导铂类耐药及与多聚腺苷二磷酸核糖聚合酶（PARP）抑制剂的相互作用被陆续发现。靶向EZH2很可能是一种有效的卵巢癌治疗策略。本文对EZH2与卵巢癌发生发展及耐药的关系进行综述,旨在为研发卵巢癌治疗新策略提供新思路。     

赖氨酸特异性组蛋白去甲基化酶1在肿瘤中的研究进展

赖氨酸特异性组蛋白去甲基化酶1(LSD1)是第一个被发现的组蛋白去甲基化酶,调控基因的转录和p53的活性,在多种肿瘤组织中高表达,与癌症的发生发展高度相关。全文对近年来LSD1在肿瘤中的最新研究进展进行综述。     

长链非编码RNA HOTAIR在宫颈癌中的相关研究进展

长链非编码RNA(lncRNA)是一类转录长度大于200个核苷酸的非编码RNA分子,其在机体内广泛参与细胞内基因的表达与调控,调控机体的多种生理、病理过程。近年来,多项研究显示lncRNA的异常表达在肿瘤的发生发展中起着重要作用。其中,HOX转录反义RNA(HOTAIR)作为lncRNA中的一种,其表达与多个肿瘤转移密切相关,尤其在宫颈癌的迁移、侵袭、转移和复发中起着关键作用。HOTAIR可能为宫颈癌潜在的新型肿瘤标记物,因此,明确其与宫颈癌的关系及其在宫颈癌的临床诊断、治疗及预后中的作用,具有重要价值,故本文就HOTAIR与宫颈癌关系的相关研究进展做一简要综述。     

LncRNA HOTAIR promotes human liver cancer stem cell malignant growth through downregulation of SETD2

Long non-coding RNA HOTAIR predicts negative tumor prognosis and exhibits oncogenic activity. Herein, we demonstrate HOTAIR promotes human liver cancer stem cell malignant growth through downregulation of SETD2. Mechanistically, HOTAIR reduces the recuritment of the CREB, P300, RNA polII onto the SETD2 promoter region that inhibits SETD2 expression and its phosphorylation. Thereby, the SETD2 binding capacity to substrate histone H3 is weakened, triggering a reduction of trimethylation on histone H3 thirty-sixth lysine, and thereby the H3K36me3–hMSH2-hMSH6-SKP2 complex is also decreased. Strikingly, the complex occupancy on chromosome is depressed, preventing from mismatch DNA repair. While reducing the degradation capacity of Skp₂ for aging histone H3 bound to damaged DNA, the aging histone repair is impaired. Furthermore, that the damaged DNA escaped to repair can causes microsatellite instability(MSI) and abnormal expression of cell cycle related genes that may trigger the hepatocarcinogenesis. This study provides evidence for HOTAIR to promote tumorigenesis via downregulating SETD2 in liver cancer stem cells.     

Loss of trimethylation at lysine 27 of histone H3 is a predictor of poor outcome in breast, ovarian, and pancreatic cancers

Methylation of lysine 27 on histone H3 (H3K27) by the EZH2 complex is an epigenetic mark that mediates gene silencing. EZH2 is overexpressed in many cancers and correlates with poor prognosis in both breast and prostate cancers. However, the status of H3K27 methylation and its clinical implication in cancer patients have not been reported. We thus examined trimethylation of H3K27 (H3K27me3) by immunohistochemistry and its association with clinical variables and prognosis in breast, ovarian, and pancreatic cancers. We found that H3K27me3 expression was significantly lower in breast, ovarian and pancreatic cancers than in normal tissues (62% in breast cancer vs. 88% in normal breast tissue, P = 0.001; 38.4% in ovarian cancer vs. 83.3% in normal ovarian tissue, P < 0.05; and 26% in pancreatic cancer vs. 89% in normal pancreatic tissue, P < 0.001). H3K27me3 expression showed significant prognostic impact in breast, ovarian and pancreatic cancers in univariate survival analyses. In all three cancer types, patients with low expression of H3K27me3 had significantly shorter overall survival time when compared with those with high H3K27me3 expression. In a multivariate model, H3K27me3 expression was an independent prognostic value for overall survival in all three cancer types. These results suggest that H3K27me3 expression is a prognostic indicator for clinical outcome in patients with breast, ovarian, and pancreatic cancers.     

Inhibition of histone demethylase,LSD2 (KDM1B), attenuates DNA methylation and increases sensitivity to DNMT inhibitor-induced apoptosis in breast cancer cells

Increasing evidence suggests that dysfunction of histone lysine demethylase is associated with abnormal chromatin remodeling and gene silencing, contributing to breast tumorigenesis. In silico analysis shows that the newly identified histone demethylase lysine-specific demethylase 2 is highly expressed in breast cancer, especially in invasive tumors. However, it is currently unknown how LSD2 regulates chromatin remodeling and gene expression regulation in breast cancer. Using short hairpin RNA, we stably knocked down LSD2 (LSD2-KD) in MDA-MB-231 breast cancer cells. LSD2-KD led to accumulation of H3K4me1/2 without changing methylation levels of other key histone lysine residues, suggesting that LSD2 acts as a bona fide H3K4 demethylase in breast cancer cells. LSD2-KD resulted in decreased colony formation and attenuated global DNA methylation in MDA-MB-231 cells. Additionally, treatment with the DNMT inhibitor, 5-aza-deoxycytidine (DAC), synergistically increased mRNA expression of aberrantly silenced genes important in breast cancer development, including PR, RARβ, ERα, SFRP1, SFRP2, and E-cadherin in LSD2-KD cells. Furthermore, LSD2-KD cells are more susceptible to cell death than scramble controls, and combined treatment with tranylcypromine, an LSD2 inhibitor, and DAC resulted in synergistic growth inhibition of breast cancer cells. DNMT inhibition by DAC in LSD2-KD cells led to internucleosomal DNA fragmentation, enhanced PARP cleavage and increased sub-G1 apoptotic cell population. These results demonstrate an important role for LSD2 in regulation of DNA methylation and gene silencing in breast cancer, and suggest that inhibition of LSD2 in combination with DNA methyltransferase inhibition represents a novel approach for epigenetic therapy of breast cancer.     

Prognostic impact of H3K27me3 expression on locoregional progression after chemoradiotherapy in esophageal squamous cell carcinoma

Background  

Trimethylation of lysine 27 on histone H3 (H3K27me3) by enhancer of zeste homolog 2 (EZH2) is an epigenetic mark that mediates gene silencing. EZH2 is overexpressed and correlates with poor prognosis in many cancers. However, the clinical implication of H3K27me3 in human malignancies has not been well established. We wished to ascertain whether a correlation exists between the expression of H3K27me3 and clinical outcome in a group of patients with esophageal squamous cell carcinoma (ESCC) treated with definitive chemoradiotherapy (CRT).