Epigenetic profiling of hepatoblastoma tumors with respect to low birth weight

描述（由申请人提供）：肝母细胞瘤（HB）是一种罕见的肝脏肿瘤，其发病率在1975年至1999年间在美国翻了一番。HB是最难治疗的儿童癌症之一，5年相对生存率接近60%。最近的证据表明，低（低体重：1500 - 2500克），特别是极低（低体重：< 1500克）出生体重婴儿的HB风险增加。有限的证据支持表观遗传改变在HB发展中的潜在作用；然而，迄今为止尚未对HB中甲基化模式的改变进行全面研究。我们的长期目标是了解表观遗传改变在HB中的作用，以及如何利用这些改变为治疗提供信息。本研究的主要目的是从84例HB肿瘤和33例正常肝组织中提取的DNA中鉴定一组启动子超甲基化改变的基因。我们的假设是，DNA甲基化模式在肿瘤和正常组织之间会有所不同，并与生存有关。为了探索这一假设，将评估以下具体目标：1)识别区分肝母细胞瘤和正常肝组织的甲基化谱；2)评估甲基化谱与HB诊断后预后之间的关系。作为一个探索性目的，我们还将研究低出生体重病例与正常出生体重病例中DNA甲基化模式的差异。我们将利用两阶段的方法来测量DNA甲基化。首先，我们将使用Illumina HumanMethylation450 BeadChip来测量甲基化，该芯片在我们发现的40个HB和20个正常肝组织中包含了整个基因组中的480,000个CpG位点。这将使我们能够选择具有HB特征的CpG位点。然后，我们将通过焦磷酸测序在44个HB和13个正常肝脏样本的验证集中验证前15个CpG位点。在完成拟议的研究后，我们期望我们将确定一组DNA甲基化改变的基因，这些基因可能与HB的发展相关，并与诊断后的生存相关。本应用中提出的研究具有重要意义，因为对HB中DNA甲基化的更全面的评估，如本文中提出的，可能会提供对这些肿瘤发展中起作用的途径的深入了解。这一知识反过来可能为患有这种疾病的儿童确定新的治疗靶点。

DESCRIPTION (provided by applicant): Hepatoblastoma (HB) is a rare liver tumor, the incidence of which doubled between 1975 and 1999 in the United States. HB is one of the least treatable forms of childhood cancer with 5-year relative survival rates near 60%. Recent evidence suggests increased risk of HB in low (LBW: 1,500-2,500 grams), and especially very low (VLBW: <1,500 grams) birth weight infants. Limited evidence exists to support a potential role of epigenetic alterations in the development of HB; however, a comprehensive study of alterations in methylation patterns in HB has not been conducted to date. Our long term objective is to understand the role of epigenetic alterations in HB and how these alterations may be used to inform treatment. The primary objective for this study is to identify a panel of genes with altered promoter hypermethylation in DNA extracted from 84 HB tumors and 33 normal liver tissues. Our hypothesis is that DNA methylation patterns will differ between tumor and normal tissue and will be associated with survival. To explore this hypothesis, the following specific aims will be evaluated: 1) identify methylation profiles that distinguish hepatoblastoma from normal liver tissue and 2) evaluate the association between methylation profiles and outcomes following a diagnosis of HB. As an exploratory aim, we will also examine differences in DNA methylation patterns in cases with low birth weight vs. cases with normal birth weight. We will utilize a two-staged approach to measure DNA methylation. First, we will measure methylation using the Illumina HumanMethylation450 BeadChip, which includes >480,000 CpG loci throughout the genome, in our discovery set of 40 HB and 20 normal liver tissues. This will allow us to select CpG sites that are characteristic of HB. We will then validate the top 15 CpG sites by pyrosequencing in our validation set of 44 HB and 13 normal liver samples. At the completion of the proposed studies, it is our expectation that we will have identified a panel of genes with altered DNA methylation that are likely to be relevant in the development of HB and associated with survival following diagnosis. The research proposed in this application is significant because a more comprehensive evaluation of DNA methylation in HB such as the one proposed here may provide insight into the pathways that play a role in the development of these tumors. This knowledge in turn may identify new targets for therapy in children with this disease.