Elucidating and targeting epigenetic oncogenic networks in pancreatic cancer

描述（由申请人提供）：表观遗传机制介导正常细胞和癌症中细胞身份的遗传控制。通过使用系统生物学方法，已经发现KDM2B（一种涉及绕过细胞衰老和体细胞重编程的含有组蛋白去甲基化酶的Jumonji结构域）在人PDAC中显著过表达，其水平随着疾病等级和阶段而增加，并且在转移中表达最高。KDM2B沉默消除了表现出上皮分化丧失的PDAC细胞系的致瘤性，而KDM2B过表达与KRASG12D合作以Jumonji依赖性方式促进小鼠模型中的PDAC形成。结合全基因组基因表达和染色质免疫沉淀研究的功能获得和丧失实验表明，KDM2B通过调节发育途径和诱导代谢重编程来驱动致瘤性。尽管PDAC的特征在于明确定义的遗传病变数量，但针对这些途径的靶向治疗的努力一直不成功。相反，PDAC中涉及的表观遗传网络在分子水平上知之甚少，并被探索为潜在的治疗靶点。我建立了新的基因工程小鼠模型，以有条件地消融和过表达KDM2B。我建议使用睡美人转座子介导的插入诱变系统进行正向遗传筛选，以确定与KDM2B在体内合作以驱动胰腺癌发展的致癌网络。鉴于组蛋白甲基化的可逆性和Jumonji结构域的重要性，我建议使用高通量筛选技术来发现KDM2B的小分子抑制剂，并在体外和体内测试其功效。该提案旨在提供对胰腺癌表观遗传学领域的进一步见解，通过体内识别和测试新的分子靶标促进对驱动肿瘤发生的分子机制的理解，并提供丰富的潜在癌症驱动突变资源，用于与PDAC中正在进行的测序工作进行交叉比较分析。

DESCRIPTION (provided by applicant): Epigenetic mechanisms mediate heritable control of cell identity in normal cells and cancer. By using a system biology approach it has been discovered that KDM2B, a Jumonji-domain containing histone demethylase implicated in bypass of cellular senescence and somatic cell reprogramming, is markedly overexpressed in human PDAC, with levels increasing with disease grade and stage, and highest expression in metastases. KDM2B silencing abrogates tumorigenicity of PDAC cell lines exhibiting loss of epithelial differentiation, whereas KDM2B overexpression cooperates with KRASG12D to promote PDAC formation in mouse models in Jumonji-dependent manner. Gain and loss-of-function experiments coupled to genome-wide gene expression and chromatin immunoprecipitation studies revealed that KDM2B drives tumorigenicity by regulating developmental pathways and inducing metabolic reprogramming. Although PDAC is characterized by a well-defined number of genetic lesions, efforts to pharmacologically target those pathways have been unsuccessful. In contrast, the epigenetic networks involved in PDAC are poorly understood at the molecular level and explored as potential therapeutic targets. I generated new genetically engineered mouse models to conditionally ablate and overexpress KDM2B. I propose to conduct a forward genetic screen using the Sleeping Beauty transposon-mediated insertional mutagenesis system to identify oncogenic networks that cooperate with KDM2B in vivo to drive pancreatic cancer development. Given the reversibility of histone methylation and the importance of the Jumonji domain, I propose to use high throughput screening technologies to discover small molecule inhibitors of KDM2B and test their efficacy in vitro and in vivo. This proposal aims to provide further insights into the field of epigenetics of pancreatic cancer, facilitate the understanding of molecular mechanism(s) that drive oncogenesis through identification and testing new molecular targets in vivo, and provide a rich resource of potential cancer driving mutations for cross-comparative analyses with ongoing sequencing efforts in PDAC.