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DNA甲基化抑制剂5-氮杂胞苷和5-氮杂-2'-脱氧胞苷对编码和非编码RNA表达的影响
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摘要
研究背景DNA甲基化是指由DNA甲基转移酶DNMTs催化,在胞嘧啶的第5位碳原子上加上一甲基基团,使之变成5-甲基胞嘧啶(5-mC)的化学修饰过程,通常发生在双核甘酸CpG中的胞嘧啶,是表观遗传重要的调控机制之一。人类的CpG以两种形式存在,一种是分散于DNA中的CpG位点,另一种是CpG位点富集的CpG岛(CpG Island), CpG岛主要分布在基因中的启动子上。在正常组织里,70%-90%的散在的CpG位点是甲基化的,而CpG岛则是非甲基化的。肿瘤的DNA甲基化改变表现为总体的甲基化水平降低与启动子区CpG岛的甲基化水平升高。抑癌基因与修复基因的甲基化导致抑癌基因沉默与修复基因失活,造成肿瘤抑制丧失与基因损伤增加;而总体低甲基化使反转录转座子、癌基因活化,使染色体不稳定。
     5-氮杂胞苷(5-Azacytidine,5-Aza-CR)与5-氮杂脱氧胞苷(5-Aza-2'-deoxycytidine,5-Aza-CdR)是两种常用的核苷类似物DNA甲基化抑制剂,均已被FDA批准用于骨髓增生异常综合症(myelodysplastic syndrome,MDS)的治疗。5-Aza-CR和5-Aza-CdR在细胞内的代谢有一定差别,5-Aza-CdR的代谢产物以磷酸盐的形式与DNA掺合;而5-Aza-CR大部分代谢产物与RNA结合,少部分代谢产物与DNA掺合。大量的临床试验表明5-Aza-CR和5-Aza-CdR均能缓解MDS病情,但近期的两个临床三期试验结果显示该两种药物在延长MDS患者的生存期上存在差异,5-Aza-CR能够明显延长生存时间,而5-Aza-CdR不能。为了探讨这种差异是否有可能是因为5-Aza-CR除了具有去DNA甲基化作用外,还能与RNA结合而干扰RNA结构和/或功能所致,本研究使用高通量筛选技术来检测这两种药物在使用等毒性剂量处理MDS/AML细胞系(P39细胞系)和实体肿瘤细胞系(T24细胞系)后对信使RNA (Message RNA, mRNA).微小RNA (microRNA, miRNA)和长链非编码RNA (Longer non-coding RNA, ncRNA)表达的影响。
     目的:比较等毒性剂量5-Aza-CR和5-Aza-CdR对肿瘤细胞系中多种RNA表达的影响,探讨5-Aza-CR和5-Aza-CdR在细胞内代谢上的差别是否可以影响这两种药物调节编码和非编码RNA表达的能力。
     方法:使用等毒性剂量处理血液系统肿瘤细胞系(MDS/AML, P39细胞系)和实体肿瘤细胞系(膀胱移形细胞癌,T24细胞系)。药物处理24小时后(Day1)更换新鲜培养液,于药物处理后48小时(Day 2)及8天(Day 8)两个时间点收集细胞。使用高通量筛选技术(microarray)来检测信使RNA (Message RNA, mRNA)、微小RNA(MicroRNA, miRNA)和长链非编码RNA (Longer non-coding RNA, ncRNA)表达,采用Limma进行差异表达分析。实时定量RT-PCR检测XAGE1D的mRNA表达,甲基化敏感性单核苷酸引物延伸(MS-SNuPE)检测XAGE1D基因启动子的甲基化状态。
     结果:两种药物均能影响mRNA、miRNA和ncRNA的表达。总体而言,5-aza-CdR能比5-aza-CR诱导更多的RNA表达上调,尤其在Day 8时这种差异更明显;Day 2时,5-aza-CR能诱导更多的RNA表达下调。在Day 8时,大部分被5-aza-CR上调的RNA也能被5-aza-CdR诱导表达上调,两种药物共同上调的基因中的一部分属于肿瘤-睾丸抗原基因(CTAs)。在CTAs表达上调的同时,CTAs转录调节因子CTCFL/BORIS表达也上调。另外,在Day 8时,两种药物均能上调白介素和干扰素信号通路中的多个基因的表达,显示该两种药物具有诱导炎症和/或免疫反应的作用。两种药物存在不同的即时效应(Day 2):5-aza-CR能显著下调非编码小RNA的表达;在T24细胞中,5-aza-CR能显著上调tRNA合成酶和参与氨基酸代谢的一些基因的表达。
     结论:5-aza-CR和5-aza-CdR这两种药物调节RNA表达的即时效应存在显著性差异,然而其持续效应的主要模式和可能的可遗传的改变是重叠的。
     目的:研究miR-886转录本是否是vault RNA2以及DNA甲基化抑制剂5-Aza-CR和5-Aza-CdR能否调节其表达。
     方法:通过cDNA末端快速扩增技术(Rapid amplification of cDNA ends, RACE)确定miR-886转录本的转录起始位点和3’末端。使用stem-loop RT-PCR检测成熟的miR-886在P39细胞系中各药物处理组中及其他四种细胞系(LD419、UROtsa、T24和UMUC3)中的表达,甲基化敏感性单核苷酸引物延伸(MS-SNuPE)检测miR-886转录本基因启动子的甲基化状态。采用连续两次转染的方法将Drosha siRNA转染至T24细胞,在第二次转染后72小时收集细胞,采用western blot及实时定量RT-PCR检测Drosha的表达,使用stem-loop RT-PCR检测成熟的miR-886及miR-21的表达。使用RNA聚合酶Ⅱ抑制剂a-amanitin处理T24细胞,分别于24小时、48小时收集细胞,采用RT-PCR来检测miR-886转录本的表达。实时定量RT-PCR及Northern blot检测miR-886转录本(vault RNA2)表达。
     结果:miR-886的转录本较一般的pri-miRNA短,其序列与miRbase预测的miRNA前体序列存在差异,可以直接形成茎环结构。无miR-886表达的P39和UMUC3细胞中,miR-886基因启动子处于高甲基化状态,而有miR-886表达的LD419、UROtsa以及T24细胞中,miR-886基因启动子处于低甲基化状态,并且DNA甲基化抑制剂5-Aza-CR和5-Aza-CdR能重新激活miR-886的表达。miR-886的转录本由RNA聚合酶Ⅲ催化转录,而且成熟miR-886的生成不依赖核糖核酸酶ⅢDrosha的加工,证实了miR-886转录本不是miRNA的前体。Northern blot的结果表明miR-886的转录本是vault RNA2,而且vault RNA2能产生miR-886或类似于miRNA的小分子RNA,并且5-Aza-CR和5-Aza-CdR在UMUC3和P39细胞中能重新激活vault RNA 2的表达。
     结论:miR-886转录本是vault RNA 2,而且vault RNA 2能产生小分子RNA,即曾被注释为miR-886-3p和miR-886-5p的小分子RNA,并且首次发现DNA甲基化调控vault RNA 2的表达。
Backgroud DNA methylation occurs almost exclusively on a cytosine in a CpG dinucleotide, and is achieved by the addition of a methyl group to the 5 position of a cytosine ring mediated by DNA methyl transferases (DNMTs). The CpG sites are asymmetrically distributed into CpG poor regions and dense regions called "CpG islands", which are often located in the promoter regions of approximately half of all protein-coding genes. CpG islands normally remain unmethylated, while the most CpG poor regions are normally methylated. DNA methylation dysregulation in cancer includes abnormal global DNA hypomethylation particularly in CpG poor region and repeat regions, which induces oncogene activation and chromosomal instability, and promoter hypermethylation of CpG islands, which leads to the silencing of some tumor suppressor genes.
     5-Azacytidine (5-Aza-CR) and 5-Aza-2'-deoxycytidine (5-Aza-CdR) are two well-known DNA methylation inhibitors, and they have been approved by the Food and Drug Administration for the treatment of myelodysplastic syndrome. Both drugs are thought to exert their effects after incorporation into DNA and RNA by covalent binding of DNA methyltransferase (DNMT). While 5-aza-CdR is only incorporated into only DNA,5-aza-CR is incorporated into both DNA and RNA.5-aza-CR is the first drug to show a survival benefit in patients with myelodysplastic syndrome. Surprisingly, the deoxyribonucleoside analog 5-aza-CdR did not have a similar positive effect on survival in a large clinical trial. Here, we have analyzed whether this difference in nucleic acid incorporation may influence the capacity of these drugs to regulate the expression of coding and non-coding RNA, and could be one possible explanation for the differences in treatment outcome.
     Objective To investigate whether the different metabolism mechanisms of 5-Aza-CR and 5-Aza-CdR influence the capacity of these drugs to regulate the expression of coding and non-coding RNA.
     Methods A hematopoietic (P39; MDS/AML) and a solid (T24; transitional cell carcinoma) cancer cell line were treated with equitoxic doses of 5-aza-CR and 5-aza-CdR. The medium was changed after 24 hours, and cells were collected 1 day (Day 2) and 7 days (Day 8) after the drug had been removed. High-throughput screening approaches, including mRNA array, miRNA array and ncRNA array, were utilized to examine the expression of mRNA, miRNA and longer non-coding RNA (ncRNA). Differential expression analysis was done using Limma. Real-time RT-PCR was used to detect the expression of XAGE1D. DNA methylation status of XAGE1D was measured by Methylation-Specific Single Nucleotide Primer Extension (Ms-SNuPE).
     Results Both drugs effect the expression of all RNA species:mRNA, microRNA and long non-coding RNA. In general,5-aza-CdR treatment upregulated considerably more RNAs than 5-aza-CR, particulaly on day 8, and more RNAs were downregulated on day 2 by 5-aza-CR. A large proportion of RNAs upregulated on day 8 after 5-aza-CR treatment were also upregulated by 5-aza-CdR. Among those upregulated genes, many are belonged to the group of cancer testis antigens (CTAs). The upregulation of CTAs coincided with upregulation of CTCFL (BORIS), which may act as a transcriptional regulator of CTAs. On day 8, multiple genes from the interleukin-and interferon pathways were upregulated by both drugs, indicating a role of induction of an inflammatory and/or immunological response. A more detailed analysis immediately after treatment revealed diverse effects of each drug:On day 2, 5-aza-CR led to a remarkable down regulation of small non-coding RNAs, and significant upregulation of tRNA synthetases and certain genes involved in amino acid metabolism was observed in T24 cells.
     Conclusion Significant differences exist in the immediate action of the two drugs, however the dominant pattern of the lasting, and possible heritable changes, is overlapping.
     Objective To explore whether miR-886 transcript is vault RNA 2. And to study whether its expression can be regulated by 5-Aza-CR and 5-Aza-CdR.
     Methods Rapid amplification of cDNA ends (RACE) was used to find the transcription start site and 3'end of mir-886 transcript. The expression of mature miR-886 was detected by stem-loop RT-PCR in P39, LD419, UROtsa, T24, and UMUC3. DNA methylation status of potential promoter of miR-886 transcript (vault RNA2) was measured by Methylation-Specific Single Nucleotide Primer Extension (Ms-SNuPE). T24 cells were transfected twice with Drosha siRNAs, and collected at 72hr after the second transfection. Expression of Drosha mRNA was detected by real-time RT-PCR, and western blot was used for protein expression. Stem-loop RT-PCR was used to measure the expression of mature miR-886 and miR-21. T24 cells were treated with a-amanitin, and harvested at 24 hr and 48hr after treatment. The expression of miR-886 transcript was detected by RT-PCR. Real-time RT-PCR and Northern blot were used to measure the expression of miR-886 transcript.
     Results Although miR-886 transcript is shorter than predicted pri-miRNA and the transcription product has the appropriate size to form a pre-miRNA hairpin, miR-886 transcript is transcribed by RNA polymerase III and not by RNA polymerase II and mature mir-886 production is independent of Drosha. These results showed miR-886 transcipt is neither pri-miRNA nor pre-miRNA. Futhermore, Northern blot results indicated that instead of miR-886 vault RNA 2 is the major products which can produce miR-886 or miRNA-like small RNA. In general, Vault RNA 2 is expressed in normal cell lines such as LD419, UROtsa. It was silenced by its promoter methylation in UMUC3 and P39 cancer cell lines. The expression of vault RNA2 can be restored by 5-aza-CR and 5-aza-CdR treatment accompanied by reduction of methylation in P39 and UMUC3 cancer cell lines,
     Conclusion miR-886 transcript is vault RNA 2, which can produce small RNA. miR-886-3p and miR-886-5p. Our study has revealed for the first time that DNA methylation can silence vault RNA2 expression. DNA methylation inhibitors. 5-aza-CR and 5-aza-CdR, can restore the expression of methylation silenced vault RNA 2 in cancer cell lines. Although vault RNA 2 is commonly silenced in cancer cell lines, the role of vault RAN2 during the tumirgenesis is still under investigation.
引文
[1]Lu Q, Qiu X, Hu N, et al. Epigenetics, disease, and therapeutic interventions.[J]. Ageing Res Rev,2006,5(4):449-467.
    [2]Egger G, Liang G, Aparicio A, et al. Epigenetics in human disease and prospects for epigenetic therapy.[J]. Nature,2004,429(6990):457-463.
    [3]Yoo C B, Jones P A. Epigenetic therapy of cancer:past, present and future.[J]. Nat Rev Drug Discov,2006,5(1):37-50.
    [4]Fenaux P, Mufti G J, Hellstrom-Lindberg E, et al. Efficacy of azacitidine compared with that of conventional care regimens in the treatment of higher-risk myelodysplastic syndromes:a randomised, open-label, phase III study.[J]. Lancet Oncol,2009,10(3):223-232.
    [5]Wijermans P, Suciu S, Baila L, et al. Low Dose Decitabine Versus Best Supportive Care in Elderly Patients with Intermediate or High Risk MDS Not Eligible for Intensive Chemotherapy:Final Results of the Randomized Phase III Study (06011) of the EORTC Leukemia and German MDS Study Groups. [C]. Blood,2008.
    [6]Barbosa-Morais N L, Dunning M J, Samarajiwa S A, et al. A re-annotation pipeline for Illumina BeadArrays:improving the interpretation of gene expression data.[J]. Nucleic Acids Res,2010,38(3):e17.
    [7]Wettenhall J M, Smyth G K. limmaGUI:a graphical user interface for linear modeling of microarray data.[J]. Bioinformatics,2004,20(18):3705-3706.
    [8]Mootha V K, Lindgren C M, Eriksson K F, et al. PGC-1 alpha-responsive genes involved in oxidative phosphorylation are coordinately downregulated in human diabetes.[J]. Nat Genet,2003,34(3):267-273.
    [9]Subramanian A, Tamayo P, Mootha V K, et al. Gene set enrichment analysis:a knowledge-based approach for interpreting genome-wide expression profiles.[J]. Proc Natl Acad Sci U S A,2005,102(43):15545-15550.
    [10]Gonzalgo M L, Jones P A. Quantitative methylation analysis using methylation-sensitive single-nucleotide primer extension (Ms-SNuPE).[J]. Methods,2002,27(2):128-133.
    [11]Gonzalgo M L, Jones P A. Rapid quantitation of methylation differences at specific sites using methylation-sensitive single nucleotide primer extension (Ms-SNuPE).[J]. Nucleic Acids Res,1997,25(12):2529-2531.
    [12]Jackson-Grusby L, Beard C, Possemato R, et al. Loss of genomic methylation causes p53-dependent apoptosis and epigenetic deregulation. [J]. Nat Genet,2001,27(1):31-39.
    [13]Khan R, Aggerholm A, Hokland P, et al. A pharmacodynamic study of 5-azacytidine in the P39 cell line.[J]. Exp Hematol,2006,34(1):35-43.
    [14]Kim W J, Kim E J, Jeong P, et al.RUNX3 inactivation by point mutations and aberrant DNA methylation in bladder tumors. [J]. Cancer Res,2005,65(20):9347-9354.
    [15]Liang G, Gonzales F A, Jones P A, et al. Analysis of gene induction in human fibroblasts and bladder cancer cells exposed to the methylation inhibitor 5-aza-2'-deoxycytidine.[J]. Cancer Res,2002,62(4):961-966.
    [16]Renaud S, Pugacheva E M, Delgado M D, et al. Expression of the CTCF-paralogous cancer-testis gene, brother of the regulator of imprinted sites (BORIS), is regulated by three alternative promoters modulated by CpG methylation and by CTCF and p53 transcription factors. [J]. Nucleic Acids Res,2007,35(21):7372-7388.
    [17]Vatolin S, Abdullaev Z, Pack S D, et al. Conditional expression of the CTCF-paralogous transcriptional factor BORIS in normal cells results in demethylation and derepression of MAGE-A1 and reactivation of other cancer-testis genes.[J]. Cancer Res,2005,65(17):7751-7762.
    [18]Compagno M, Lim W K, Grunn A, et al. Mutations of multiple genes cause deregulation of NF-kappaB in diffuse large B-cell lymphoma.[J]. Nature,2009,459(7247):717-721.
    [19]Novak U, Rinaldi A, Kwee I, et al. The NF-{kappa}B negative regulator TNFAIP3 (A20) is inactivated by somatic mutations and genomic deletions in marginal zone lymphomas.[J]. Blood,2009,113(20):4918-4921.
    [20]Saito Y, Liang G, Egger G, et al. Specific activation of microRNA-127 with downregulation of the proto-oncogene BCL6 by chromatin-modifying drugs in human cancer cells.[J]. Cancer Cell,2006,9(6):435-443.
    [21]Saito Y, Friedman J M, Chihara Y, et al. Epigenetic therapy upregulates the tumor suppressor microRNA-126 and its host gene EGFL7 in human cancer cells.[J]. Biochem Biophys Res Commun,2009,379(3):726-731.
    [22]Mercer T R, Dinger M E, Mattick J S. Long non-coding RNAs:insights into functions.[J]. Nat Rev Genet,2009,10(3):155-159.
    [23]Flotho C, Claus R, Batz C, et al. The DNA methyltransferase inhibitors azacitidine, decitabine and zebularine exert differential effects on cancer gene expression in acute myeloid leukemia cells.[J]. Leukemia,2009,23(6):1019-1028.
    [24]Gronbaek K, Hother C, Jones P A. Epigenetic changes in cancer. [J]. APMIS,2007,115(10):1039-1059.
    [25]Fandy T E, Herman J G, Kerns P, et al. Early epigenetic changes and DNA damage do not predict clinical response in an overlapping schedule of 5-azacytidine and entinostat in patients with myeloid malignancies. [J]. Blood,2009,114(13):2764-2773.
    [26]Weber J, Salgaller M, Samid D, et al. Expression of the MAGE-1 tumor antigen is up-regulated by the demethylating agent 5-aza-2'-deoxycytidine.[J]. Cancer Res,1994,54(7):1766-1771.
    [27]De Smet C, Lurquin C, Lethe B, et al. DNA methylation is the primary silencing mechanism for a set of germ line- and tumor-specific genes with a CpG-rich promoter.[J]. Mol Cell Biol,1999,19(11):7327-7335.
    [28]Phillips J E, Corces V G. CTCF:master weaver of the genome.[J]. Cell,2009,137(7):1194-1211.
    [29]Zlatanova J, Caiafa P. CCCTC-binding factor:to loop or to bridge.[J]. Cell Mol Life Sci,2009,66(10):1647-1660.
    [30]Hong J A, Kang Y, Abdullaev Z, et al. Reciprocal binding of CTCF and BORIS to the NY-ESO-1 promoter coincides with derepression of this cancer-testis gene in lung cancer cells.[J]. Cancer Res,2005,65(17):7763-7774.
    [31]Caballero O L, Chen Y T. Cancer/testis (CT) antigens:potential targets for immunotherapy.[J]. Cancer Sci,2009,100(11):2014-2021.
    [32]Braun T, Carvalho G, Coquelle A, et al. NF-kappaB constitutes a potential therapeutic target in high-risk myelodysplastic syndrome. [J]. Blood,2006,107(3):1156-1165.
    [33]Khan R, Schmidt-Mende J, Karimi M, et al. Hypomethylation and apoptosis in 5-azacytidine-treated myeloid cells.[J]. Exp Hematol,2008,36(2):149-157.
    [34]Peikert T, Specks U, Farver C, et al. Melanoma antigen A4 is expressed in non-small cell lung cancers and promotes apoptosis. [J]. Cancer Res,2006,66(9):4693-4700.
    [35]Fabre C, Grosjean J, Tailler M, et al. A novel effect of DNA methyltransferase and histone deacetylase inhibitors:NFkappaB inhibition in malignant myeloblasts.[J]. Cell Cycle,2008,7(14):2139-2145.
    [36]Compagno M, Lim W K, Grunn A, et al. Mutations of multiple genes cause deregulation of NF-kappaB in diffuse large B-cell lymphoma.[J]. Nature,2009,459(7247):717-721.
    [37]Croce C M. Causes and consequences of microRNA dysregulation in cancer.[J]. Nat Rev Genet,2009,10(10):704-714.
    [38]Schaefer M, Hagemann S, Hanna K, et al. Azacytidine inhibits RNA methylation at DNMT2 target sites in human cancer cell lines.[J]. Cancer Res,2009,69(20):8127-8132.
    [39]Momparler R L, Siegel S, Avila F, et al. Effect of tRNA from 5-azacytidine-treated hamster fibrosarcoma cells on protein synthesis in vitro in a cell-free system.[J]. Biochem Pharmacol,1976,25(4):389-392.
    [40]Landgraf P, Rusu M, Sheridan R, et al. A mammalian microRNA expression atlas based on small RNA library sequencing. [J]. Cell,2007,129(7):1401-1414.
    [41]Nandy C, Mrazek J, Stoiber H, et al. Epstein-barr virus-induced expression of a novel human vault RNA.[J]. J Mol Biol,2009,388(4):776-784.
    [42]Stadler P F, Chen J J, Hackermuller J, et al. Evolution of vault RNAs.[J]. Mol Biol Evol,2009,26(9):1975-1991.
    [43]Mrazek J, Kreutmayer S B, Grasser F A, et al. Subtractive hybridization identifies novel differentially expressed ncRNA species in EBV-infected human B cells.[J]. Nucleic Acids Res,2007,35(10):e73.
    [44]Kickhoefer V A, Emre N, Stephen A G, et al. Identification of conserved vault RNA expression elements and a non-expressed mouse vault RNA gene.[J]. Gene,2003,309(2):65-70.
    [45]Vilalta A, Kickhoefer V A, Rome L H, et al. The rat vault RNA gene contains a unique RNA polymerase III promoter composed of both external and internal elements that function synergistically.[J]. J Biol Chem,1994,269(47):29752-29759.
    [46]Kickhoefer V A, Searles R P, Kedersha N L, et al. Vault ribonucleoprotein particles from rat and bullfrog contain a related small RNA that is transcribed by RNA polymerase III.[J]. J Biol Chem,1993,268(11):7868-7873.
    [47]Chen C, Ridzon D A, Broomer A J, et al. Real-time quantification of microRNAs by stem-loop RT-PCR.[J]. Nucleic Acids Res,2005,33(20):e179.
    [48]Lee Y, Kim M, Han J, et al. MicroRNA genes are transcribed by RNA polymerase II.[J]. EMBO J,2004,23(20):4051-4060.
    [49]Lee Y, Ahn C, Han J, et al. The nuclear RNase III Drosha initiates microRNA processing. [J]. Nature,2003,425(6956):415-419.
    [50]Persson H, Kvist A, Vallon-Christersson J, et al. The non-coding RNA of the multidrug resistance-linked vault particle encodes multiple regulatory small RNAs.[J]. Nat Cell Biol,2009,11(10):1268-1271.
    [51]Bartel D P. MicroRNAs:genomics, biogenesis, mechanism, and function.[J]. Cell,2004,116(2):281-297.
    [52]Rodriguez A, Griffiths-Jones S, Ashurst J L, et al. Identification of mammalian microRNA host genes and transcription units. [J]. Genome Res,2004,14(10A):1902-1910.
    [53]Kim Y K, Kim V N. Processing of intronic microRNAs.[J]. EMBO J,2007,26(3):775-783.
    [54]Cai X, Hagedorn C H, Cullen B R. Human microRNAs are processed from capped, polyadenylated transcripts that can also function as mRNAs.[J]. RNA,2004,10(12):1957-1966.
    [55]Borchert G M, Lanier W, Davidson B L. RNA polymerase III transcribes human microRNAs.[J]. Nat Struct Mol Biol,2006,13(12):1097-1101.
    [56]Bortolin-Cavaille M L, Dance M, Weber M, et al. C19MC microRNAs are processed from introns of large Pol-II, non-protein-coding transcripts.[J]. Nucleic Acids Res,2009,37(10):3464-3473.
    [57]Raha D, Wang Z, Moqtaderi Z, et al. Close association of RNA polymerase II and many transcription factors with Pol III genes.[J]. Proc Natl Acad Sci U S A,2010,107(8):3639-3644.
    [58]Bohnsack M T, Czaplinski K, Gorlich D. Exportin 5 is a RanGTP-dependent dsRNA-binding protein that mediates nuclear export of pre-miRNAs.[J]. RNA,2004,10(2):185-191.
    [59]Hutvagner G, Mclachlan J, Pasquinelli A E, et al. A cellular function for the RNA-interference enzyme Dicer in the maturation of the let-7 small temporal RNA.[J].Science,2001,293(5531):834-838.
    [60]Okamura K, Hagen J W, Duan H, et al. The mirtron pathway generates microRNA-class regulatory RNAs in Drosophila.[J]. Cell,2007,130(1):89-100.
    [61]Ruby J G, Jan C H, Bartel D P. Intronic microRNA precursors that bypass Drosha processing.[J]. Nature,2007,448(7149):83-86.
    [62]Winter J, Jung S, Keller S, et al. Many roads to maturity:microRNA biogenesis pathways and their regulation.[J]. Nat Cell Biol,2009,11(3):228-234.
    [63]Kedersha N L, Rome L H. Isolation and characterization of a novel ribonucleoprotein particle:large structures contain a single species of small RNA.[J]. J Cell Biol,1986,103(3):699-709.
    [64]Kedersha N L, Hill D F, Kronquist K E, et al. Subpopulations of liver coated vesicles resolved by preparative agarose gel electrophoresis.[J]. J Cell Biol,1986,103(1):287-297.
    [65]Kickhoefer V A, Siva A C, Kedersha N L, et al. The 193-kD vault protein, VPARP, is a novel poly(ADP-ribose) polymerase.[J]. J Cell Biol,1999,146(5):917-928.
    [66]Kickhoefer V A, Stephen A G, Harrington L, et al. Vaults and telomerase share a common subunit, TEP1.[J]. J Biol Chem,1999,274(46):32712-32717.
    [67]Tanaka H, Kato K, Yamashita E, et al. The structure of rat liver vault at 3.5 angstrom resolution.[J]. Science,2009,323(5912):384-388.
    [68]Kong L B, Siva A C, Kickhoefer V A, et al. RNA location and modeling of a WD40 repeat domain within the vault.[J]. RNA,2000,6(6):890-900.
    [69]van Zon A, Mossink M H, Schoester M, et al. Multiple human vault RNAs. Expression and association with the vault complex. [J]. J Biol Chem,2001,276(40):37715-37721.
    [70]Berger W, Steiner E, Grusch M, et al. Vaults and the major vault protein: novel roles in signal pathway regulation and immunity.[J]. Cell Mol Life Sci,2009,66(1):43-61.
    [71]Kickhoefer V A, Rajavel K S, Scheffer G L, et al. Vaults are up-regulated in multidrug-resistant cancer cell lines.[J]. J Biol Chem,1998,273(15):8971-8974.
    [1]Wolffe A. Chromatin:Structure and Function (3rd edition). [Z]. Academic Press Inc.,1998.
    [2]Jenuwein T, Allis C D. Translating the histone code.[J]. Science.2001, 293(5532):1074-1080.
    [3]Fuks F, Hurd P J, Wolf D, et al. The methyl-CpG-binding protein MeCP2 links DNA methylation to histone methylation.[J]. J Biol Chem.2003,278(6):4035-4040.
    [4]Jones P A, Takai D. The role of DNA methylation in mammalian epigenetics.[J]. Science.2001,293(5532):1068-1070.
    [5]Antequera F, Bird A. Number of CpG islands and genes in human and mouse.[J]. Proc Natl Acad Sci U S A.1993,90(24):11995-11999.
    [6]Richardson B. Impact of aging on DNA methylation.[J]. Ageing Res Rev.2003, 2(3):245-261.
    [7]Karpf A R, Matsui S. Genetic disruption of cytosine DNA methyltransferase enzymes induces chromosomal instability in human cancer cells.[J]. Cancer Res. 2005,65(19):8635-8639.
    [8]Attwood J T, Yung R L, Richardson B C. DNA methylation and the regulation of gene transcription. [J]. Cell Mol Life Sci.2002,59(2):241-257.
    [9]Mukai T, Sekiguchi M. Gene silencing in phenomena related to DNA repair.[J]. Oncogene.2002,21(58):9033-9042.
    [10]Ehrlich M. The ICF syndrome, a DNA methyltransferase 3B deficiency and immunodeficiency disease.[J]. Clin Immunol.2003,109(1):17-28.
    [11]Amir R E, Van den Veyver I B, Wan M, et al. Rett syndrome is caused by mutations in X-linked MECP2, encoding methyl-CpG-binding protein 2.[J]. Nat Genet.1999,23(2):185-188.
    [12]Fraga M F, Ballestar E, Paz M F, et al. Epigenetic differences arise during the lifetime of monozygotic twins. [J]. Proc Natl Acad Sci U S A.2005,102(30): 10604-10609.
    [13]Burzynski S R. Aging:gene silencing or gene activation?[J]. Med Hypotheses. 2005,64(1):201-208.
    [14]Zhang Z, Deng C, Lu Q, et al. Age-dependent DNA methylation changes in the ITGAL (CD11a) promoter.[J]. Mech Ageing Dev.2002,123(9):1257-1268.
    [15]Ray D, Wu A, Wilkinson J E, et al. Aging in heterozygous Dnmtl-deficient mice:effects on survival, the DNA methylation genes, and the development of amyloidosis.[J]. J Gerontol A Biol Sci Med Sci.2006,61(2):115-124.
    [16]Toyota M, Ahuja N, Ohe-Toyota M, et al. CpG island methylator phenotype in colorectal cancer.[J]. Proc Natl Acad Sci U S A.1999,96(15):8681-8686.
    [17]Issa J P. Age-related epigenetic changes and the immune system.[J]. Clin Immunol.2003,109(1):103-108.
    [18]Youssef E M, Estecio M R, Issa J P. Methylation and regulation of expression of different retinoic acid receptor beta isoforms in human colon cancer.[J]. Cancer Biol Ther.2004,3(1):82-86.
    [19]Issa J P. The epigenetics of colorectal cancer.[J]. Ann N Y Acad Sci.2000,910: 140-153,153-155.
    [20]Galusca B, Dumollard J M, Lassandre S, et al. Global DNA methylation evaluation:potential complementary marker in differential diagnosis of thyroid neoplasia.[J]. Virchows Arch.2005,447(1):18-23.
    [21]Szyf M, Pakneshan P, Rabbani S A. DNA methylation and breast cancer.[J]. Biochem Pharmacol.2004,68(6):1187-1197.
    [22]de Capoa A, Musolino A, Della R S, et al. DNA demethylation is directly related to tumour progression:evidence in normal, pre-malignant and malignant cells from uterine cervix samples.[J]. Oncol Rep.2003,10(3):545-549.
    [23]Florl A R, Steinhoff C, Muller M, et al. Coordinate hypermethylation at specific genes in prostate carcinoma precedes LINE-1 hypomethylation.[J]. Br J Cancer.2004,91(5):985-994.
    [24]Kaneda A, Tsukamoto T, Takamura-Enya T, et al. Frequent hypomethylation in multiple promoter CpG islands is associated with global hypomethylation, but not with frequent promoter hypermethylation.[J]. Cancer Sci.2004,95(1):58-64.
    [25]Chalitchagorn K, Shuangshoti S, Hourpai N, et al. Distinctive pattern of LINE-1 methylation level in normal tissues and the association with carcinogenesis.[J]. Oncogene.2004,23(54):8841-8846.
    [26]Kimura F, Florl A R, Seifert H H, et al. Destabilization of chromosome 9 in transitional cell carcinoma of the urinary bladder.[J]. Br J Cancer.2001,85(12): 1887-1893.
    [27]Frigola J, Sole X, Paz M F, et al. Differential DNA hypermethylation and hypomethylation signatures in colorectal cancer.[J]. Hum Mol Genet.2005,14(2): 319-326.
    [28]Suter C M, Martin D I, Ward R L. Hypomethylation of L1 retrotransposons in colorectal cancer and adjacent normal tissue.[J]. Int J Colorectal Dis.2004,19(2): 95-101.
    [29]Ogishima T, Shiina H, Breault J E, et al. Promoter CpG hypomethylation and transcription factor EGR1 hyperactivate heparanase expression in bladder cancer.[J]. Oncogene.2005,24(45):6765-6772.
    [30]Okada H, Kimura M T, Tan D, et al. Frequent trefoil factor 3 (TFF3) overexpression and promoter hypomethylation in mouse and human hepatocellular carcinomas.[J]. Int J Oncol.2005,26(2):369-377.
    [31]Fujisawa K, Maesawa C, Sato R, et al. Epigenetic status and aberrant expression of the maspin gene in human hepato-biliary tract carcinomas.[J]. Lab Invest.2005,85(2):214-224.
    [32]Oshimo Y, Nakayama H, Ito R, et al. Promoter methylation of cyclin D2 gene in gastric carcinoma.[J]. Int J Oncol.2003,23(6):1663-1670.
    [33]Gupta A, Godwin A K, Vanderveer L, et al. Hypomethylation of the synuclein gamma gene CpG island promotes its aberrant expression in breast carcinoma and ovarian carcinoma.[J]. Cancer Res.2003,63(3):664-673.
    [34]Chan M W, Chan L W, Tang N L, et al. Hypermethylation of multiple genes in tumor tissues and voided urine in urinary bladder cancer patients.[J]. Clin Cancer Res. 2002,8(2):464-470.
    [35]Maruyama R, Sugio K, Yoshino I, et al. Hypermethylation of FHIT as a prognostic marker in nonsmall cell lung carcinoma.[J]. Cancer.2004,100(7): 1472-1477.
    [36]Strunnikova M, Schagdarsurengin U, Kehlen A, et al. Chromatin inactivation precedes de novo DNA methylation during the progressive epigenetic silencing of the RASSF1A promoter.[J]. Mol Cell Biol.2005,25(10):3923-3933.
    [37]Akino K, Toyota M, Suzuki H, et al. The Ras effector RASSF2 is a novel tumor-suppressor gene in human colorectal cancer.[J]. Gastroenterology.2005, 129(1):156-169.
    [38]Taniguchi H, Yamamoto H, Hirata T, et al. Frequent epigenetic inactivation of Wnt inhibitory factor-1 in human gastrointestinal cancers.[J]. Oncogene.2005, 24(53):7946-7952.
    [39]Hong S H, Kim H G, Chung W B, et al. DNA hypermethylation of tumor-related genes in gastric carcinoma.[J]. J Korean Med Sci.2005,20(2): 236-241.
    [40]Shieh Y S, Shiah S G, Jeng H H, et al. DNA methyltransferase 1 expression and promoter methylation of E-cadherin in mucoepidermoid carcinoma. [J]. Cancer. 2005,104(5):1013-1021.
    [41]Ishida E, Nakamura M, Ikuta M, et al. Promotor hypermethylation of p14ARF is a key alteration for progression of oral squamous cell carcinoma.[J]. Oral Oncol. 2005,41(6):614-622.
    [42]Viswanathan M, Tsuchida N, Shanmugam G. Promoter hypermethylation profile of tumor-associated genes p16, p15, hMLH1, MGMT and E-cadherin in oral squamous cell carcinoma.[J]. Int J Cancer.2003,105(1):41-46.
    [43]Park H J, Yu E, Shim Y H. DNA methyltransferase expression and DNA hypermethylation in human hepatocellular carcinoma.[J]. Cancer Lett.2006,233(2): 271-278.
    [44]Jeronimo C, Henrique R, Hoque M O, et al. A quantitative promoter methylation profile of prostate cancer.[J]. Clin Cancer Res.2004,10(24):8472-8478.
    [45]Marsit C J, Kim D H, Liu M, et al. Hypermethylation of RASSF1A and BLU tumor suppressor genes in non-small cell lung cancer:implications for tobacco smoking during adolescence.[J]. Int J Cancer.2005,114(2):219-223.
    [46]Tozawa T, Tamura G, Honda T, et al. Promoter hypermethylation of DAP-kinase is associated with poor survival in primary biliary tract carcinoma patients.[J]. Cancer Sci.2004,95(9):736-740.
    [47]Fang M Z, Jin Z, Wang Y, et al. Promoter hypermethylation and inactivation of O(6)-methylguanine-DNA methyltransferase in esophageal squamous cell carcinomas and its reactivation in cell lines.[J]. Int J Oncol.2005,26(3):615-622.
    [48]Puri S K, Si L, Fan C Y, et al. Aberrant promoter hypermethylation of multiple genes in head and neck squamous cell carcinoma.[J]. Am J Otolaryngol.2005,26(1): 12-17.
    [49]Maruya S, Issa J P, Weber R S, et al. Differential methylation status of tumor-associated genes in head and neck squamous carcinoma:incidence and potential implications.[J]. Clin Cancer Res.2004,10(11):3825-3830.
    [50]Lee S, Hwang K S, Lee H J, et al. Aberrant CpG island hypermethylation of multiple genes in colorectal neoplasia.[J]. Lab Invest.2004,84(7):884-893.
    [51]Bai A H, Tong J H, To K F, et al. Promoter hypermethylation of tumor-related genes in the progression of colorectal neoplasia.[J]. Int J Cancer.2004,112(5): 846-853.
    [52]House M G, Guo M, Iacobuzio-Donahue C, et al. Molecular progression of promoter methylation in intraductal papillary mucinous neoplasms (IPMN) of the pancreas.[J]. Carcinogenesis.2003,24(2):193-198.
    [53]Kwong J, Lo K W, To K F, et al. Promoter hypermethylation of multiple genes in nasopharyngeal carcinoma.[J]. Clin Cancer Res.2002,8(1):131-137.
    [54]Dong S M, Kim H S, Rha S H, et al. Promoter hypermethylation of multiple genes in carcinoma of the uterine cervix.[J]. Clin Cancer Res.2001,7(7):1982-1986.
    [55]Li S, Rong M, Iacopetta B. DNA hypermethylation in breast cancer and its association with clinicopathological features.[J]. Cancer Lett.2006,237(2):272-280.
    [56]Yeo W, Wong W L, Wong N, et al. High frequency of promoter hypermethylation of RASSF1A in tumorous and non-tumourous tissue of breast cancer.[J]. Pathology.2005,37(2):125-130.
    [57]Melki J R, Vincent P C, Brown R D, et al. Hypermethylation of E-cadherin in leukemia.[J]. Blood.2000,95(10):3208-3213.
    [58]Mitani Y, Oue N, Hamai Y, et al. Histone H3 acetylation is associated with reduced p21(WAF1/CIP1) expression by gastric carcinoma.[J]. J Pathol.2005,205(1): 65-73.
    [59]Hamai Y, Oue N, Mitani Y, et al. DNA hypermethylation and histone hypoacetylation of the HLTF gene are associated with reduced expression in gastric carcinoma.[J]. Cancer Sci.2003,94(8):692-698.
    [60]Ohike N, Maass N, Mundhenke C, et al. Clinicopathological significance and molecular regulation of maspin expression in ductal adenocarcinoma of the pancreas.[J]. Cancer Lett.2003,199(2):193-200.
    [61]Richardson B C. Role of DNA methylation in the regulation of cell function: autoimmunity, aging and cancer.[J]. J Nutr.2002,132(8 Suppl):2401S-2405S.
    [62]Deng C, Kaplan M J, Yang J, et al. Decreased Ras-mitogen-activated protein kinase signaling may cause DNA hypomethylation in T lymphocytes from lupus patients.[J]. Arthritis Rheum.2001,44(2):397-407.
    [63]Cooper G S, Stroehla B C. The epidemiology of autoimmune diseases.[J]. Autoimmun Rev.2003,2(3):119-125.
    [64]Richardson B C, Strahler J R, Pivirotto T S, et al. Phenotypic and functional similarities between 5-azacytidine-treated T cells and a T cell subset in patients with active systemic lupus erythematosus.[J]. Arthritis Rheum.1992,35(6):647-662.
    [65]Lu Q, Kaplan M, Ray D, et al. Demethylation of ITGAL (CD11a) regulatory sequences in systemic lupus erythematosus.[J]. Arthritis Rheum.2002,46(5): 1282-1291.
    [66]Yung R, Powers D, Johnson K, et al. Mechanisms of drug-induced lupus. Ⅱ. T cells overexpressing lymphocyte function-associated antigen 1 become autoreactive and cause a lupuslike disease in syngeneic mice.[J]. J Clin Invest.1996,97(12): 2866-2871.
    [67]Kaplan M J, Lu Q, Wu A, et al. Demethylation of promoter regulatory elements contributes to perforin overexpression in CD4+ lupus T cells.[J]. J Immunol.2004, 172(6):3652-3661.
    [68]Lu Q, Wu A, Richardson B C. Demethylation of the same promoter sequence increases CD70 expression in lupus T cells and T cells treated with lupus-inducing drugs.[J]. J Immunol.2005,174(10):6212-6219.
    [69]Oelke K, Lu Q, Richardson D, et al. Overexpression of CD70 and overstimulation of IgG synthesis by lupus T cells and T cells treated with DNA methylation inhibitors.[J]. Arthritis Rheum.2004,50(6):1850-1860.
    [70]Davis C D, Uthus E O. DNA methylation, cancer susceptibility, and nutrient interactions.[J]. Exp Biol Med (Maywood).2004,229(10):988-995.
    [71]Kim Y I. Folate and DNA methylation:a mechanistic link between folate deficiency and colorectal cancer?[J]. Cancer Epidemiol Biomarkers Prev.2004,13(4): 511-519.
    [72]Pogribny I P, James S J, Jernigan S, et al. Genomic hypomethylation is specific for preneoplastic liver in folate/methyl deficient rats and does not occur in non-target tissues.[J]. Mutat Res.2004,548(1-2):53-59.
    [73]Pogribny I P, Ross S A, Wise C, et al. Irreversible global DNA hypomethylation as a key step in hepatocarcinogenesis induced by dietary methyl deficiency.[J]. Mutat Res.2006,593(1-2):80-87.
    [74]Jacob R A, Gretz D M, Taylor P C, et al. Moderate folate depletion increases plasma homocysteine and decreases lymphocyte DNA methylation in postmenopausal women.[J]. J Nutr.1998,128(7):1204-1212.
    [75]Rampersaud G C, Kauwell G P, Hutson A D, et al. Genomic DNA methylation decreases in response to moderate folate depletion in elderly women.[J]. Am J Clin Nutr.2000,72(4):998-1003.
    [76]Jhaveri M S, Wagner C, Trepel J B. Impact of extracellular folate levels on global gene expression.[J]. Mol Pharmacol.2001,60(6):1288-1295.
    [77]Pufulete M, Emery P W, Sanders T A. Folate, DNA methylation and colo-rectal cancer.[J]. Proc Nutr Soc.2003,62(2):437-445.
    [78]Choi S W, Friso S, Keyes M K, et al. Folate supplementation increases genomic DNA methylation in the liver of elder rats.[J]. Br J Nutr.2005,93(1):31-35.
    [79]Pufulete M, Al-Ghnaniem R, Khushal A, et al. Effect of folic acid supplementation on genomic DNA methylation in patients with colorectal adenoma.[J]. Gut.2005,54(5):648-653.
    [80]Choi S W, Friso S, Keyes M K, et al. Folate supplementation increases genomic DNA methylation in the liver of elder rats.[J]. Br J Nutr.2005,93(1):31-35.
    [81]Kim Y I. Nutritional epigenetics:impact of folate deficiency on DNA methylation and colon cancer susceptibility.[J]. J Nutr.2005,135(11):2703-2709.
    [82]Zhou L, Cheng X, Connolly B A, et al. Zebularine:a novel DNA methylation inhibitor that forms a covalent complex with DNA methyltransferases.[J]. J Mol Biol. 2002,321(4):591-599.
    [83]Kaminskas E, Farrell A, Abraham S, et al. Approval summary:azacitidine for treatment of myelodysplastic syndrome subtypes.[J]. Clin Cancer Res.2005,11(10): 3604-3608.
    [84]Marcucci G, Silverman L, Eller M, et al. Bioavailability of azacitidine subcutaneous versus intravenous in patients with the myelodysplastic syndromes.[J]. J Clin Pharmacol.2005,45(5):597-602.
    [85]Issa J P, Garcia-Manero G, Giles F J, et al. Phase 1 study of low-dose prolonged exposure schedules of the hypomethylating agent 5-aza-2'-deoxycytidine (decitabine) in hematopoietic malignancies.[J]. Blood.2004,103(5):1635-1640.
    [86]Samlowski W E, Leachman S A, Wade M, et al. Evaluation of a 7-day continuous intravenous infusion of decitabine:inhibition of promoter-specific and global genomic DNA methylation.[J]. J Clin Oncol.2005,23(17):3897-3905.
    [87]Issa J P, Gharibyan V, Cortes J, et al. Phase II study of low-dose decitabine in patients with chronic myelogenous leukemia resistant to imatinib mesylate.[J]. J Clin Oncol.2005,23(17):3948-3956.
    [88]Sullivan M, Hahn K, Kolesar J M. Azacitidine:a novel agent for myelodysplastic syndromes.[J]. Am J Health Syst Pharm.2005,62(15):1567-1573.
    [89]Saunthararajah Y, Desimone J. Clinical studies with fetal hemoglobin-enhancing agents in sickle cell disease.[J]. Semin Hematol.2004,41(4 Suppl 6):11-16.
    [90]Chan K K, Giannini D D, Staroscik J A, et al.5-Azacytidine hydrolysis kinetics measured by high-pressure liquid chromatography and 13C-NMR spectroscopy.[J]. J Pharm Sci.1979,68(7):807-812.
    [91]Murgo A J. Innovative approaches to the clinical development of DNA methylation inhibitors as epigenetic remodeling drugs.[J]. Semin Oncol.2005,32(5): 458-464.
    [92]Marquez V E, Kelley J A, Agbaria R, et al. Zebularine:a unique molecule for an epigenetically based strategy in cancer chemotherapy.[J]. Ann N Y Acad Sci.2005, 1058:246-254.
    [93]Cheng J C, Weisenberger D J, Gonzales F A, et al. Continuous zebularine treatment effectively sustains demethylation in human bladder cancer cells.[J]. Mol Cell Biol.2004,24(3):1270-1278.
    [94]Cheng J C, Matsen C B, Gonzales F A, et al. Inhibition of DNA methylation and reactivation of silenced genes by zebularine.[J]. J Natl Cancer Inst.2003,95(5): 399-409.
    [95]Holleran J L, Parise R A, Joseph E, et al. Plasma pharmacokinetics, oral bioavailability, and interspecies scaling of the DNA methyltransferase inhibitor, zebularine.[J]. Clin Cancer Res.2005,11(10):3862-3868.
    [96]Ben-Kasus T, Ben-Zvi Z, Marquez V E, et al. Metabolic activation of zebularine, a novel DNA methylation inhibitor, in human bladder carcinoma cells.[J]. Biochem Pharmacol.2005,70(1):121-133.
    [97]Fang M Z, Wang Y, Ai N, et al. Tea polyphenol (-)-epigallocatechin-3-gallate inhibits DNA methyltransferase and reactivates methylation-silenced genes in cancer cell lines.[J]. Cancer Res.2003,63(22):7563-7570.
    [98]Villar-Garea A, Fraga M F, Espada J, et al. Procaine is a DNA-demethylating agent with growth-inhibitory effects in human cancer cells.[J]. Cancer Res.2003, 63(16):4984-4989.
    [99]Lee B H, Yegnasubramanian S, Lin X, et al. Procainamide is a specific inhibitor of DNA methyltransferase 1.[J]. J Biol Chem.2005,280(49):40749-40756.
    [100]Deng C, Lu Q, Zhang Z, et al. Hydralazine may induce autoimmunity by inhibiting extracellular signal-regulated kinase pathway signaling.[J]. Arthritis Rheum.2003,48(3):746-756.
    [101]Altundag O, Altundag K, Gunduz M. DNA methylation inhibitor, procainamide, may decrease the tamoxifen resistance by inducing overexpression of the estrogen receptor beta in breast cancer patients.[J]. Med Hypotheses.2004,63(4): 684-687.
    [102]Segura-Pacheco B, Trejo-Becerril C, Perez-Cardenas E, et al. Reactivation of tumor suppressor genes by the cardiovascular drugs hydralazine and procainamide and their potential use in cancer therapy.[J]. Clin Cancer Res.2003,9(5):1596-1603.
    [103]Zambrano P, Segura-Pacheco B, Perez-Cardenas E, et al. A phase I study of hydralazine to demethylate and reactivate the expression of tumor suppressor genes.[J]. BMC Cancer.2005,5:44.
    [104]Parker B S, Cutts S M, Nudelman A, et al. Mitoxantrone mediates demethylation and reexpression of cyclin d2, estrogen receptor and 14.3.3sigma in breast cancer cells.[J]. Cancer Biol Ther.2003,2(3):259-263.
    [105]Beaulieu N F M M A. Antitumor activity of MG98, an antisense oligonucleotide targeting DNA methyltransferase-1(DNMT1).[Z].2001:7 (Suppl.), 3728S-3800S.
    [106]Davis A J, Gelmon K A, Siu L L, et al. Phase I and pharmacologic study of the human DNA methyltransferase antisense oligodeoxynucleotide MG98 given as a 21-day continuous infusion every 4 weeks.[J]. Invest New Drugs.2003,21(1):85-97.
    [107]Stewart D J, Donehower R C, Eisenhauer E A, et al. A phase I pharmacokinetic and pharmacodynamic study of the DNA methyltransferase 1 inhibitor MG98 administered twice weekly.[J]. Ann Oncol.2003,14(5):766-774.
    [108]Saikawa Y, Kubota T, Maeda S, et al. Inhibition of DNA methyltransferase by antisense oligodeoxynucleotide modifies cell characteristics in gastric cancer cell lines.[J]. Oncol Rep.2004,12(3):527-531.
    [109]Leu Y W, Rahmatpanah F, Shi H, et al. Double RNA interference of DNMT3b and DNMT1 enhances DNA demethylation and gene reactivation.[J]. Cancer Res. 2003,63(19):6110-6115.
    [110]Suzuki M, Sunaga N, Shames D S, et al. RNA interference-mediated knockdown of DNA methyltransferase 1 leads to promoter demethylation and gene re-expression in human lung and breast cancer cells.[J]. Cancer Res.2004,64(9): 3137-3143.
    [111]Castanotto D, Tommasi S, Li M, et al. Short hairpin RNA-directed cytosine (CpG) methylation of the RASSF1A gene promoter in HeLa cells.[J]. Mol Ther.2005, 12(1):179-183.
    [112]Kawasaki H, Taira K. Induction of DNA methylation and gene silencing by short interfering RNAs in human cells.[J]. Nature.2004,431(7005):211-217.
    [113]Morris K V, Chan S W, Jacobsen S E, et al. Small interfering RNA-induced transcriptional gene silencing in human cells.[J]. Science.2004,305(5688): 1289-1292.
    [114]Park C W, Chen Z, Kren B T, et al. Double-stranded siRNA targeted to the huntingtin gene does not induce DNA methylation.[J]. Biochem Biophys Res Commun.2004,323(1):275-280.
    [115]Marks P A, Richon V M, Kelly W K, et al. Histone deacetylase inhibitors: development as cancer therapy.[J]. Novartis Found Symp.2004,259:269-281, 281-288.
    [116]Kelly W K, Richon V M, O'Connor O, et al. Phase Ⅰ clinical trial of histone deacetylase inhibitor:suberoylanilide hydroxamic acid administered intravenously.[J]. Clin Cancer Res.2003,9(10 Pt 1):3578-3588.
    [117]Kelly W K, O'Connor O A, Krug L M, et al. Phase Ⅰ study of an oral histone deacetylase inhibitor, suberoylanilide hydroxamic acid, in patients with advanced cancer.[J]. J Clin Oncol.2005,23(17):3923-3931.
    [118]Byrd J C, Marcucci G, Parthun M R, et al. A phase 1 and pharmacodynamic study of depsipeptide (FK228) in chronic lymphocytic leukemia and acute myeloid leukemia.[J]. Blood.2005,105(3):959-967.
    [119]Marshall J L, Rizvi N, Kauh J, et al. A phase Ⅰ trial of depsipeptide (FR901228) in patients with advanced cancer.[J]. J Exp Ther Oncol.2002,2(6):325-332.
    [120]Pilatrino C, Cilloni D, Messa E, et al. Increase in platelet count in older, poor-risk patients with acute myeloid leukemia or myelodysplastic syndrome treated with valproic acid and all-trans retinoic acid.[J]. Cancer.2005,104(1):101-109.
    [121]Chavez-Blanco A, Segura-Pacheco B, Perez-Cardenas E, et al. Histone acetylation and histone deacetylase activity of magnesium valproate in tumor and peripheral blood of patients with cervical cancer. A phase Ⅰ study.[J]. Mol Cancer. 2005,4(1):22.
    [122]Gilbert J, Baker S D, Bowling M K, et al. A phase Ⅰ dose escalation and bioavailability study of oral sodium phenylbutyrate in patients with refractory solid tumor malignancies.[J]. Clin Cancer Res.2001,7(8):2292-2300.
    [123]Phuphanich S, Baker S D, Grossman S A, et al. Oral sodium phenylbutyrate in patients with recurrent malignant gliomas:a dose escalation and pharmacologic study.[J]. Neuro Oncol.2005,7(2):177-182.
    [124]Ryan Q C, Headlee D, Acharya M, et al. Phase I and pharmacokinetic study of MS-275, a histone deacetylase inhibitor, in patients with advanced and refractory solid tumors or lymphoma.[J]. J Clin Oncol.2005,23(17):3912-3922.
    [125]Prakash S, Foster B J, Meyer M, et al. Chronic oral administration of CI-994:a phase 1 study.[J]. Invest New Drugs.2001,19(1):1-11.
    [126]Undevia S D, Kindler H L, Janisch L, et al. A phase I study of the oral combination of CI-994, a putative histone deacetylase inhibitor, and capecitabine.[J]. Ann Oncol.2004,15(11):1705-1711.
    [127]Bovenzi V, Momparler R L. Antineoplastic action of 5-aza-2'-deoxycytidine and histone deacetylase inhibitor and their effect on the expression of retinoic acid receptor beta and estrogen receptor alpha genes in breast carcinoma cells.[J]. Cancer Chemother Pharmacol.2001,48(1):71-76.
    [128]Ghoshal K, Datta J, Majumder S, et al. Inhibitors of histone deacetylase and DNA methyltransferase synergistically activate the methylated metallothionein I promoter by activating the transcription factor MTF-1 and forming an open chromatin structure.[J]. Mol Cell Biol.2002,22(23):8302-8319.
    [129]Belinsky S A, Klinge D M, Stidley C A, et al. Inhibition of DNA methylation and histone deacetylation prevents murine lung cancer.[J]. Cancer Res.2003,63(21): 7089-7093.
    [130]Xiong Y, Dowdy S C, Podratz K C, et al. Histone deacetylase inhibitors decrease DNA methyltransferase-3B messenger RNA stability and down-regulate de novo DNA methyltransferase activity in human endometrial cells.[J]. Cancer Res. 2005,65(7):2684-2689.

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