"Oncorequisite" Genes in MYC-mediated Transformation

MYC是一种有效的原癌基因，在人类癌症中异常且广泛表达， 白血病和淋巴瘤。这项提案的长期目标是发现那些 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， 因此可能作为开发新的分子治疗剂的有用靶点。使用转基因 小鼠Myc在胸腺细胞中表达并可靠地产生T细胞白血病的斑马鱼模型， 进行了显性遗传修饰筛选，以确定和研究“致癌必要”基因，其突变 延缓白血病的发病我筛选出了一个编码二氢硫辛酰胺琥珀酰转移酶的基因 （DLST），其杂合失活显著延迟了 斑马鱼中表达Myc癌基因的淋巴瘤/白血病。斑马鱼Dlst在肿瘤中上调 与Myc过表达的正常细胞相比，Myc过表达的细胞。另外这款 DLST的上调与8期细胞比例增加和基因组不稳定性有关。 Dlst减少50%的肿瘤细胞倾向于处于G1期，并且形态上更分化 一个稳定的基因组我已经阐明了DLST的人类直系同源物在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。小分子治疗人类 T-ALL细胞系和斑马鱼淋巴瘤是有效的，导致体外活细胞较少和延迟 体内肿瘤进展。因此，我认为这种克雷布循环转移酶的人类直系同源物是一种 有希望的治疗靶点，用于治疗人T-ALL。在拨款的ROO阶段，我将进一步 描述DLST在人神经母细胞瘤病理生理学中的重要性（新目标1），并确定其 协同基因和途径（新目标2）。与此同时，我将确定额外的“致癌必要”基因， 通过斑马鱼遗传筛选的MYC介导的转化（Aim 3）。这一做法的合理性和可行性 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.