Identification of glioma tumor-initiating cells

描述(申请人提供)：恶性胶质瘤是最常见的原发脑肿瘤，其特点是侵袭性生长和对现有治疗方法的顽固性。在胶质瘤细胞类型中，多能CD133+细胞具有在免疫缺陷小鼠中引发疾病的能力(Singh等人，2004年)。脑肿瘤中肿瘤起始细胞类型的鉴定表明，与血液系统恶性肿瘤一样，胶质瘤的细胞异质性代表了分化状态的分级安排(Clarke等人，2006年)。根据这一范例，消除肿瘤启动细胞可能提供最大的治疗益处(Park等人，2009年)。在胶质瘤生物学中研究这一基本概念的一个主要障碍是缺乏细胞标记物来表征胶质瘤肿瘤起始细胞的表型异质性。我们在初级异种移植模型中的背景数据表明，CD133的表达包括具有不同生物学特性的不同的胶质瘤细胞亚群。为了研究CD133表达所包含的细胞异质性，我们提出用从恶性胶质瘤亚型分离的CD133+细胞免疫七鳃鳗，以产生针对胶质瘤前体细胞的单抗。Lamprey抗体在结构上与我们的抗体不同，将分析它们在直接原位异种移植模型中识别肿瘤启动细胞及其谱系的潜力。原理验证研究表明，可针对代表B淋巴细胞分化不同阶段的人肿瘤细胞制备重组单抗VLR。我们推测，除了无颌脊椎动物的VLR抗体独有的其他优势外，哺乳动物抗体库中原本不允许的细胞表位，由于自身耐受性，将可用于七鳃鳗抗体(Herrin等人，2008年)。 公共卫生相关性：恶性胶质瘤对目前的治疗方法是顽固性的，目前这种疾病的患者预后很差。识别导致肿瘤生长和复发的细胞类型可能会导致更有效的治疗方法的开发。在这项建议中，一种新的方法，无颌脊椎动物的适应性免疫系统，将被用来在直接原位异种移植模型中识别胶质瘤肿瘤启动细胞及其谱系。

DESCRIPTION (provided by applicant): Malignant gliomas are the most common primary brain tumors and are characterized by invasive growth and recalcitrance to current therapies. Among glioma cell types, multipotent CD133+ cells have the capacity to initiate disease in immunodeficient mice (Singh et al., 2004). The identification of a tumor-initiating cell type in brain tumors suggests that, like hematological malignancies, the cellular heterogeneity of gliomas represents a hierarchical arrangement of differentiation states (Clarke et al., 2006). According to this paradigm, elimination of tumor-initiating cells may provide the greatest therapeutic benefit (Park et al., 2009). A primary impediment to investigating this fundamental concept in glioma biology is the lack of cell markers for characterizing the phenotypic heterogeneity of glioma tumor-initiating cells. Our background data in a primary xenotransplantation model suggest that CD133 expression encompasses discrete subpopulations of glioma cells with different biological characteristics. To study the cellular heterogeneity encompassed by CD133 expression, we propose to generate monoclonal variable lymphocyte receptor (VLR) antibodies for glioma progenitor cells by immunizing lampreys with CD133+ cells isolated from malignant glioma subtypes. The lamprey antibodies, which are structurally different proteins than our antibodies, will be analyzed for their potential to identify tumor-initiating cells and their lineages in a direct orthotopic xenotransplantation model. Proof-of-principle studies demonstrate that recombinant monoclonal VLR antibodies can be made against human tumor cells representative of different stages in B lymphocyte differentiation. We postulate that among other advantages unique to the VLR antibodies of jawless vertebrates, cellular epitopes otherwise impermissible to a mammalian antibody repertoire, because of self-tolerance, will be accessible to lamprey antibodies (Herrin et al., 2008). PUBLIC HEALTH RELEVANCE: Malignant gliomas are recalcitrant to current therapies and patients with this disease currently have a poor prognosis. The identification of cell types responsible for tumor growth and recurrence may lead to the development of more effective therapies. In this proposal a novel method, the adaptive immune system of jawless vertebrates, will be used to identify glioma tumor-initiating cells and their lineages in a direct orthotopic xenotransplantation model.