PREDICTIVE AND THERAPEUTIC UTILITIES OF EPIGENETIC CHANGES IN CHROMATIN IN MELANO

由于染色质重塑引起的基因活性的异常变化在癌细胞中很常见。它们涉及到 胞嘧啶-鸟嘌呤(CpG)启动子区域富含CpG岛的胞嘧啶甲基化/去甲基化 组蛋白的转录后修饰(乙酰化/甲基化)。DNA的异常获得或丢失 甲基化导致参与肿瘤发生和维持的基因表达改变 表型包括肿瘤抑制因子、凋亡因子、DNA修复酶、黏附分子和 免疫调节剂。染色质表观遗传变化的可逆性是临床研究的基础。 DNA去甲基化试剂5-氮杂-2‘-脱氧胞苷(5-aza-CDR，又称 地西他滨)，其类似物5-氮胞苷，以及组蛋白脱乙酰酶(HDAC)抑制剂。我们的目标是找出 与黑色素瘤细胞和肿瘤生长停滞相关的表观基因组标记。这些标记可以是 预测应答和利用表观遗传修饰剂调整治疗以适应应答的检测基础 病人。在目标1中，我们将评估对地西他滨敏感的患者基因表达的整体变化。 和耐药黑色素瘤细胞，并确定可以预测生长抑制的基因表达谱。 在目标2中，我们将询问基因组范围内敏感的DNA启动子甲基化模式的变化 和耐药黑色素瘤细胞对5-aza-CDR的反应，并将其与受影响基因的图谱相关联 我们还将确定黑色素瘤肿瘤中DNA甲基化的全球变化 取自正在接受5-氮胞苷治疗的患者，并将其与培养中的黑色素瘤细胞进行比较。 在目标3中，我们将验证5-氮杂-镉反应调节区的表观遗传修饰(DNA甲基化 被认为对导致生长停滞至关重要的基因。我们将使用多种生物信息学方法 对来自染色质修饰和基因的信息进行数据挖掘和整合 表达式数组数据。我们预见，这些信息将有助于设计出一种经济有效的表观遗传修饰物。 可以预测黑色素瘤患者对这类药物的疗效和监测治疗反应的测试。 该项目包括5-氮胞苷的I期试验，是多学科的，涉及 基础科学家、分子生物学家、生物信息学和临床肿瘤学家。

Aberrant changes in gene activity due to chromatin remodeling are frequent in cancer cells. They involve methylation/demethylation of cytosine at cytosine-guanine (CpG) pair rich islands in promoter regions and post-transcriptional modifications (acetylation/methylation) of histones. Aberrant gain or loss of DNA methylation causes altered expression of genes involved in tumorigenesis and maintenance of the malignant phenotype including tumor suppressors, apoptotic factors, DNA repair enzymes, adhesion molecules, and immunomodulators. The reversible nature of epigenetic changes in chromatin is the rationale for clinical development of the DNA demethylation agents 5-Aza-2'-deoxy-cytidine (5-Aza-CdR, also known as decitabine), its analogue 5-azacytidine, and the histone deacetylase (HDAC) inhibitors. Our goal is to identify epigenomic markers associated with growth arrest of melanoma cells and tumors. These markers can be the basis for an assay for predicting responses and tailoring treatment with epigenetic modifiers to responsive patients. In Aim 1 we will assess global changes in gene expression in response to decitabine in sensitive and resistant melanoma cells and determine gene-expression profiles that can predict growth suppression. In Aim 2 we will interrogate genome-wide changes in the patterns of DNA promoter methylation in sensitive and resistant melanoma cells in response to 5-Aza-CdR, and correlate it to the profiles of affected genes revealed in Aim 1. We will also determine the global changes in DNA methylation in melanoma tumors excised from patients undergoing treatment with 5-azacytidine and compare it to melanoma cells in culture. In Aim 3 we will verify the epigenetic modification (DNA methylation) in regulatory regions of 5-Aza-CdRresponsive genes deemed critical to inducing growth arrest. We will employ multiple bioinformatics methods to perform data mining and integration of the information derived from the chromatin modification and gene expression array data. We foresee that the information will help devise a cost-effective epigenetic-modifier test that can predict efficacy and monitor therapeutic responses to this class of agents in melanoma patients. This project includes a Phase I trial with 5-azacytidine, is multidisciplinary, involving the concerted efforts of basic scientists, molecular biologists, bioinformatics and clinical oncologists.