Cancer Biology in the Zebrafish

描述（由申请人提供）：斑马鱼是一种强大的脊椎动物遗传模型，最近被用作了解癌症的系统。我们已经分离出19个细胞周期突变，在我们的模型系统中有几个突变基因与癌症有关。我们对B-myb的研究发现了一种影响细胞周期蛋白B并参与癌症的新途径，我们最近对分离酶突变的研究表明，基因组不稳定性使上皮细胞易患癌症。为此，我们计划研究两种基于ras通路激活的独立癌症模型。RAS家族成员和下游靶点在许多人类癌症中发生突变，包括黑色素瘤和横纹肌肉瘤。在第一个模型中，BRAF和p53缺乏诱导黑色素瘤。在第二个模型中，组成性KRAS等位基因导致10日龄胚胎性横纹肌肉瘤。这是所有脊椎动物中最快的肿瘤模型。在这两种情况下，我们已经证明了引发肿瘤的细胞是可移植的，分别代表了黑色素细胞和肌源性分化的早期阶段。我们假设RAS诱导将在不同组织类型的肿瘤中激活类似的自我更新途径。利用转基因鱼，我们计划用一些报告结构标记癌细胞，并确定可移植的肿瘤细胞亚群。这些模型将进一步用于了解在致癌细胞群中起作用的信号通路。我们计划确定wnt-前列腺素途径是否可以改变致癌细胞的功能。我们还计划进行化学筛选，确定抑制癌症干细胞的分子。已经发现了两种新的化学物质，可以阻断BRAF中早期神经嵴祖细胞的扩张；P53缺陷胚胎。这些化学物质现在正在我们的斑马鱼模型中测试阻止成人黑色素瘤的能力。我们的研究将有助于更好地了解癌症细胞的异质性，也将为横纹肌肉瘤和黑色素瘤提供潜在的治疗方法。公共卫生相关性：癌症是一种难以治疗的疾病，因为化疗后残留的细胞会使肿瘤重现，导致复发。在这里，我们计划检查肿瘤中这些罕见细胞的分化，并找到破坏它们的途径。通过确定这些途径，可以设计出新的治疗方法，与传统的化疗结合使用来治疗癌症。

DESCRIPTION (provided by applicant): The zebrafish is a powerful vertebrate genetic model and has recently been used as a system to understand cancer. We have isolated 19 cell cycle mutants and several mutated genes are associated with cancer in our model system. Our studies of B-myb identified a novel pathway that affects cyclin B and participates in cancer, and our recent study of a separase mutant demonstrated that genome instability predisposes epithelial cells to cancer. For this proposal, we plan to investigate two independent cancer models based on ras pathway activation. RAS family members and the downstream targets are mutated in a number of human cancers, including melanoma and rhabdomyosarcoma. In the first model, BRAF and p53 deficiency induced melanoma. In a second model, a constitutive KRAS allele leads to embryonal rhabdomyosarcoma at 10 days of age. This is the fastest tumor model in any vertebrate. In both cases, we have demonstrated that the cells that initiate the tumor are transplantable and represent early stages of melanocytic and myogenic differentiation, respectively. We hypothesize that RAS induction will activate similar self-renewal pathways within tumors of different tissue types. Using transgenic fish, we plan to label the cancer cells with a number of reporter constructs and determine the subpopulation of tumor cells that are transplantable. The models will be further used to understand the signaling pathways operative in the cancer-initiating cell population. We plan to determine if the wnt-prostaglandin pathway can modify the ability of the cancer-initiating cell to function. We also plan to undertake a chemical screen defining molecules that will inhibit cancer stem cells. Two novel chemicals have already been found that block an expansion of early neural crest progenitors in the BRAF;p53 deficiency embryos. These chemicals are now being tested in our zebrafish model for the ability to block adult melanoma. Our studies will lead to a better understanding of cell heterogeneity within a cancer and will also lead to potential therapies for rhabdomyosarcoma and melanoma. PUBLIC HEALTH RELEVANCE: Cancer is a difficult disease to treat because cells remaining after chemotherapy can recapitulate the tumor, leading to relapse. Here we plan to examine the differentiation of these rare cells within a tumor, and find pathways that disrupt them. By defining such pathways, new therapies can be designed to use in conjunction with conventional chemotherapy in the treatment of cancer.