MBD2 as a Target for Cancer Prevention and Treatment

描述(申请人提供)：在人类实体器官癌症的体细胞基因组改变中，只有DNA甲基化的变化持续发生(90%的病例)，出现得较早(首先出现在癌前病变中)，并且可以逆转(DNA序列保持完整)。CpG岛序列的高甲基化包括许多基因的5‘转录调控区，可通过招募5-mCpG结合域(MBD)家族蛋白来抑制基因转录。在MBD家族蛋白中，Mbd2是一个非常有吸引力的癌症预防和治疗靶点：APC mm/+小鼠容易发生肠道肿瘤，当饲养到Mbd2-/-背景时，患肠腺瘤的几率减少约10倍。本项目将探索的治疗策略是选择性靶向Mbd2转录抑制途径。为了发现小分子Mbd2途径抑制剂，将使用一种新的阶段性“高通量”筛选，以GSTP1的CpG岛为特征，已知该岛在前列腺癌、乳腺癌和肝癌中通过体细胞超甲基化和Mbd2介导的抑制而“沉默”。新的“先导”化合物将在“沉默的”基因重新激活时的效力和效果以及在癌症预防和治疗的动物模型研究中的治疗指数方面进行表征。具体目标是：(I)从高甲基化的GSTP1启动子序列中筛选出100,000种选择性激活转录的化合物，(Ii)表征“先导”化合物的分子作用机制，以及(Iii)在小鼠模型中评估临床前抗癌效果和毒性。

DESCRIPTION (provided by applicant): Of somatic genome alterations in human solid organ cancers, only changes in DNA methylation occur consistently (>90% of cases), arise early (first appearing in preneoplastic lesions), and can be reversed (the DNA sequence remains intact). Hypermethylation of CpG island sequences, which encompass the 5' transcriptional regulatory regions of many genes, can lead to repression of gene transcription via the recruitment of 5-mCpG-binding domain (MBD) family proteins. Of the MBD family proteins, MBD2 is a very attractive target for cancer prevention and treatment: Apc Mm/+ mice, prone to intestinal tumorigenesis, develop some 10-fold fewer intestinal adenomas when bred to an Mbd2 -/- background. The therapeutic strategy to be explored in this Project features the selective targeting of the MBD2 transcriptional repression pathway. To discover small molecule MBD2 pathway inhibitors, a novel staged "highthroughput" screen will be used, featuring the CpG island of GSTP1, known to be "silenced" in prostate, breast, and liver cancers via somatic hypermethylation and MBD2-mediated repression. New "lead" compounds will then be characterized for potency and efficacy at "silenced" gene reactivation, and for therapeutic index in animal model studies of cancer prevention and treatment. The Specific Aims to be pursued are: (i) the screening of 100,000 compounds for selective activation of transcription from hypermethylated GSTP1 promoter sequences, (ii) the characterization of "lead" compounds for molecular mechanisms of action, and (iii) the evaluation of preclinical anti-cancer efficacy and toxicity in mouse models.