DNA Methylation in Non-Hodgkin's Lymphomas

我们实验室的主要活动是研究肿瘤发生中的DNA甲基化，这一过程通常在许多类型的人类癌症中被称为CpG岛的富含GC的序列中观察到，并且经常与转录沉默有关。以非霍奇金淋巴瘤(NHL)为模型系统，我们的发现驱动的初步研究表明，DNA超甲基化不是一个随机事件；许多CpG岛基因座容易发生甲基化改变。由于这种表观遗传突变，控制细胞关键功能的基因的表达可能 变得沉默，导致肿瘤细胞克隆性增殖。因此，关键CpG岛基因座对DNA高甲基化的不同易感性可能会影响不同NHL亚型的发展，并可能有助于解释肿瘤生长和治疗结果的差异。我们已经确定了几个差异甲基化的基因，可能与淋巴肿大有关。我们的中心假设：B细胞的分化受到CpG岛甲基化的影响，这通常会导致基因转录的沉默。我们进一步假设 1)NHL的组织学分类实际上包含不止一种临床疾病；2)NHL细胞中CpG岛基因的高甲基化可以产生与临床亚型相关的独特的分子标记；3)解剖这些复杂的表观遗传学特征需要了解正常和肿瘤B细胞中的基因甲基化 差异化。这项应用将扩展我们目前版本的甲基化特异性寡核苷酸(MSO)微阵列，这项发明结合了亚硫酸氢盐治疗方案的能力和寡核苷酸微阵列的多功能性，并将这一创新技术应用于研究B细胞NHL和处于相似分化阶段的正常B细胞的DNA甲基化，并将这些变化与基因沉默和分类相关联。我们计划通过追求四个具体目标来验证我们的假设：1.建立一个MSO微阵列，用于分析80个基因中约4,000个座位的启动子超甲基化；2.确定CpG岛甲基化模式，表征NHL类别的亚组及其假定的B细胞分化的正常阶段；3.将MSO定义的启动子高甲基化状态与基因表达相关联；4.开发和应用数据管理、分析和可视化工具来破译NHL类别的甲基化特征。这项拟议的研究有望对DNA甲基化驱动的与B细胞相关的基因沉默的潜在机制产生重要的见解 非霍奇金淋巴瘤临床亚型的分化发展。

The major activity in our laboratory is studies of DNA methylation in tumorigenesis, a process commonly observed in GC-rich sequences called CpG islands in many types of human cancers and is often associated with transcriptional silencing. Using non-Hodgkin's lymphoma (NHL) as a model system, our discovery-driven preliminary studies demonstrate that DNA hypermethylation is not a random event; many CpG island loci are susceptible to methylation alteration. As a result of this epigenetic mutation, the expression of genes that govern key functions of the cell may become silent, leading to clonal proliferation of tumor cells. Differential susceptibility of critical CpG island loci to DNA hypermethylation may therefore influence the development of different NHL subtypes and may help explain differences in tumor growth and treatment outcomes. We have identified several loci that are differentially methylated and may be involved in lymphomagenesis. Our Central Hypothesis: B-cell differentiation is affected by methylation of CpG islands and this frequently leads to silencing of gene transcription. We further hypothesize that 1) Histological classes of NHL actually contain more than one clinical disease; 2) Hypermethylation of CpG island loci in NHL cells can generate unique molecular signatures that are associated with clinical subtypes and; 3) Dissecting these complex epigenetic profiles requires an understanding of gene methylation in normal, as well as neoplastic, B-cell differentiation. This application will expand a current version of our Methylation-Specific Oligonucleotide (MSO) microarray, an invention that combines the power of the bisulfite treatment protocol with the versatility of oligonucleotide microarrays, and apply this innovative technique to study DNA methylation in cases of B-cell NHL and normal B-cells at similar stages of differentiation, and relate these changes to gene silencing and classification. We plan to test our hypotheses by pursuing 4 specific aims; 1. Generate an MSO microarray for analysis of promoter hypermethylation at about 4,000 loci in 80 genes; 2. Determine patterns of CpG island methylation that characterize subsets of NHL classes and their putative normal stage of B-cell differentiation; 3. Correlate the status of promoter hypermethylation defined by MSO with gene expression; 4. Develop and apply data management, analysis and visualization tools to decipher methylation profiles of NHL classes. The proposed studies are expected to yield important insights into potential mechanisms of DNA methylation-driven gene silencing related to B-cell differentiation and development of clinical subtypes of NHL.