Non-nucleoside inhibitors of DNA methyl transferase I

描述(由申请人提供)：获得基因组改变是人类癌症的一个决定性特征。癌症化疗依赖于细胞死亡或凋亡途径来根除包含这些变化的细胞。在正常的DNA复制和有丝分裂过程中，维持适当的DNA甲基化水平是必要的。干扰正确和适当的甲基化导致与肿瘤细胞转录沉默相关的非突变变化。细胞凋亡途径上的基因转录沉默使化疗效果丧失，这类肿瘤对经典疗法无效，且与不良预后相关。DNA中胞嘧啶的表观遗传甲基化发生在基因启动子内密集的CpG二核苷酸重复序列中的CpG位点，并由DNA甲基转移酶(DNMT)催化。能够抑制DNMT的治疗药物可以重新激活因高甲基化而沉默的基因，因此，设计和开发新型DNMT抑制剂是一个有价值的目标，特别是在沉默的基因保持完整和功能的情况下。我们在天然产物分离、组合生物合成和并行组合合成的基础上构建了独特的天然产物衍生物库。我们的文库由结构组成，保留了天然产品的拓扑和立体化学复杂性，但准备起来很简单。在筛选我们的抗人DNMT-1酶的文库时，我们发现含有异吲哚核心支架的化合物是非常好的抑制剂，其Ki值低至20微摩尔。在这项申请中，我们试图证明我们可以开发出有效的和选择性的DNMT-1抑制剂。我们进一步试图证明我们的抑制剂导致一个模型表观遗传沉默的基因，人MLH1的重新激活。

DESCRIPTION (provided by applicant): The acquisition of genomic alterations is a defining feature of human cancers. Cancer chemotherapy relies upon the cell death or apoptotic pathway to eradicate cells containing these alterations. The maintenance of appropriate methylation levels in DNA is necessary during normal DNA replication and mitosis. Disruption of correct and appropriate methylation leads to non-mutagenic changes associated with transcriptional silencing in tumor cells. Transcriptional silencing of genes along the apoptotic pathway abrogates the efficacy of chemotherapy and such tumors are refractory to classical therapy and associated with a poor prognosis. Epigenetic methylation of cytosine in DNA occurs at CpG sites in dense clusters of CpG dinucleotide repeats within gene promoters and is catalyzed by DNA methyl transferase enzymes (Dnmt's). Therapeutics that can inhibit Dnmt can reactivate genes silenced by hypermethylation, therefore, the design and development of novel Dnmt inhibitors is a worthy goal especially as the silenced genes remain intact and functional. We have constructed unique libraries of natural product derivatives based upon natural product isolation, combinatorial biosynthesis and parallel combinatorial synthesis. Our libraries are composed of structures that retain the topological and stereochemical complexity of natural products yet are straightforward to prepare. In screening our libraries against the human Dnmt-1 enzyme we discovered that compounds with an isoindolinone core scaffold were excellent inhibitors with Ki values as low as 20 micromolar. In this application we seek to demonstrate that we can develop potent and selective inhibitors of Dnmt-1. We further seek to demonstrate that our inhibitors cause reactivation of a model epigenetically silenced gene, human MLH1.