"Oncorequisite" Genes in MYC-mediated Transformation

MYC是一种强有力的原癌基因，在人类癌症中异常广泛表达，包括 白血病和淋巴瘤。这项提议的长期目标是发现 维持MYC驱动的肿瘤，特别是T细胞急性淋巴细胞白血病(T-ALL)所必需的，以及 因此，可能成为开发新的分子疗法的有用靶点。使用转基因技术 在斑马鱼模型中，小鼠Myc在胸腺细胞中表达，并可靠地产生T细胞白血病，即 进行显性遗传修饰物筛选，以确定和研究其突变的“癌必需”基因 延缓白血病的发病。我的屏幕精确定位了一个编码二氢硫胺琥珀酸基转移酶的特定基因 (DLST)，其杂合失活显著延迟了 表达Myc癌基因的斑马鱼的淋巴瘤/白血病。斑马鱼Dlst在肿瘤中表达上调 Myc过表达的细胞与不表达Myc的正常细胞相比。此外，这一点 DLST上调与8期细胞比例增加和基因组不稳定有关。 Dlst减少50%的肿瘤细胞倾向于处于G1期，并且在形态上更分化 拥有稳定的基因组。我已经阐明了人类DLST直系同源基因在T-ALL中的重要性，并发现 DLST在大多数T-ALL细胞系中异常上调。小分子药物治疗人与人 T-ALL细胞系和斑马鱼对淋巴瘤有效，导致细胞在体外存活较差和延迟 肿瘤在体内的进展。因此，我认为这个Kreb循环转移酶的人类同源基因是一种 治疗人类T-ALL的有前景的治疗靶点。在赠款的Roo阶段，我将进一步 鉴定DLST在人类神经母细胞瘤病理生理学中的重要性(新目标1)并鉴定其 协同基因和途径(新目标2)。同时，我将确定更多的“癌必备”基因 斑马鱼遗传筛选MYC介导的转化(目标3)。这样做的理由和可行性 我在K99阶段获得的数据很好地说明了这种方法。

MYC, a potent proto-oncogene, is aberrantly and widely expressed in human cancers, including the leukemias and lymphomas. The long-term goal of this proposal is to discover the molecules that are necessary to sustain MYC-driven tumors, T-cell acute lymphoblastic leukemia (T-ALL) in particular, and hence might serve as useful targets for the development of novel molecular therapeutics. Using a transgenic zebrafish model in which murine Myc is expressed in thymocytes and reliably generates T-cell leukemia, I conducted a dominant genetic modifier screen to identify and study "oncorequisite" genes whose mutation delays the onset of leukemia. My screen pinpointed a specific gene encoding dihydrolipoamide Ssuccinyltransferase (DLST) whose heterozygous inactivation significantly delays the onset of lymphoma/leukemia in zebrafish expressing the Myc oncogene. Zebrafish Dlst was upregulated in tumor cells with Myc overexpression, compared to normal cells without Myc overexpression. In addition, this upreguiation of DLST was associated with an increased fraction of cells in 8 phase and genomic instability. Tumor cells with 50% reduction of Dlst tended to be in G1 phase and morphologically more differentiated with a stable genome. I have clarified the importance of the human ortholog of DLST in T-ALL and found that DLST is aberrantly upregulated in the majority of T-ALL cell lines. Small molecule treatment of both human T-ALL cell lines and zebrafish with lymphoma is effective, leading to less viable cells in vitro and delayed tumor progression in vivo. Hence, I consider the human ortholog of this Kreb's cycle transferase as a promising therapeutic target for treating human T-ALL. During ROO phase of the grant, I will further characterize the importance of DLST in human neuroblastoma pathophysiology (new Aim 1) and identify its synergic genes and pathways (new Aim 2). Meanwhile, I will identify additional "oncorequisite" genes in MYC-mediated transformation through zebrafish genetic screens (Aim 3). The rationale and feasibility of this approach are well-illustrated by my data acquired during the K99 phase.