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，最近已被用作了解癌症的系统。在我们的模型系统中，我们已经分离出19个细胞周期突变体，并且几个突变基因与癌症相关。我们对B-myB的研究确定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体的研究表明，基因组不稳定性使上皮细胞易患癌症。对于这个建议，我们计划研究两个独立的癌症模型的基础上ras通路激活。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缺陷诱导黑色素瘤。在第二个模型中，组成型KRAS等位基因导致10日龄的胚胎性横纹肌肉瘤。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，启动肿瘤的细胞是可移植的，并分别代表黑素细胞和肌细胞分化的早期阶段。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。使用转基因鱼，我们计划用一些报告构建体标记癌细胞，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癌症起始细胞群中起作用的信号通路。我们计划确定wnt-前列腺素通路是否可以改变癌症起始细胞的功能。我们还计划进行化学筛选，确定抑制癌症干细胞的分子。已经发现两种新的化学物质可以阻止BRAF;p53缺陷胚胎中早期神经嵴祖细胞的扩增。这些化学物质现在正在我们的斑马鱼模型中测试阻断成人黑色素瘤的能力。我们的研究将导致更好地了解癌症中的细胞异质性，也将导致横纹肌肉瘤和黑色素瘤的潜在疗法。公共卫生相关性：癌症是一种很难治疗的疾病，因为化疗后残留的细胞会重演肿瘤，导致复发。在这里，我们计划检查这些罕见细胞在肿瘤中的分化，并找到破坏它们的途径。通过定义这些途径，可以设计新的治疗方法，与传统的化疗结合使用，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.