Phenotypic Plasticity in Human Neuroblastoma

人类神经母细胞瘤的表型可塑性

• 批准号: 7007743
• 负责人: ROBERT A ROSS
• 金额: $ 24.01万
• 依托单位: FORDHAM UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-12-10 至 2008-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7007743
• 关键词: athymic mouse; cell differentiation; cell transformation; human tissue; immunocytochemistry; messenger RNA; neoplasm /cancer genetics; nerve /myelin protein; neural plasticity; neuroblastoma; phenotype; protein purification; protooncogene; transfection

DESCRIPTION (provided by applicant): Neuroblastoma, a tumor of the embryonic neural crest, is highly malignant and poorly responsive to conventional therapy, yet tumor cells retain the capacity for differentiation. This cancer is ultimately fatal in most patients and, thus, there is an urgent need to identify new agents and treatment strategies. Our long term goal is to understand the relationship between malignancy and cell differentiation state. Cell phenotype and amplification of the N-myc proto-oncogene are two factors that influence the malignant potential of neuroblastoma. In cell lines, N-myc expression and malignancy are dramatically affected by cell phenotype. Neuroblastic cells express high levels of N-myc and are tumorigenic whereas non-neuronal S-type cells from the same parental cell line contain markedly lower amounts of N-myc RNA/protein and are non-tumorigenic. The two cell types arise from a third cell type, malignant I-type stem cell. Moreover, experimentally induced changes in cell phenotype can directly affect N-myc expression and this oncoprotein, in turn, regulates specific downstream genes affecting cell growth and malignancy. These observations form the basis for our central hypothesis: Cell differentiation state, in particular the malignant stem cell phenotype, as well as N-myc expression levels directly regulate the malignant potential of neuroblastoma cells. One lineage-specific factor regulating N-myc expression is HuD, a neuronal-specific RNA-binding protein. HuD regulates the splicing/stability of N-myc mRNA and, in transfection experiments, it influences the amounts of cellular N-myc mRNA and protein. N-myc, in turn, regulates nestin and this neuroectodermal intermediate filament protein appears to mediate several of the oncogenic function of N-myc. The two aims of this proposal examine different aspects of our hypothesis. The focus of Aim #1 is to determine the mechanisms by which HuD interacts with N-nyc mRNA and thereby regulates its expression and, as a corollary, whether loss of one HuD allele is a critical factor in the development of N-myc amplification and tumor aggressiveness. Second, we will study the mechanism by which N-myc regulates nestin and how nestin augments the cell's malignant potential. Studies proposed in Aim # 2 will 1) establish whether the relative number of I-type stem cells in tumors correlates with tumor stage, aggressiveness, or event-free survival and is predictive for progressive disease and 2) isolate and characterize component phenotypes from tumors. Knowledge gained of the differentiation status of cells in tumors with a favorable or unfavorable prognosis and of factors that can directly affect cellular differentiation, and thereby malignant potential, is highly likely to have important application to the treatment of neuroblastoma.

描述（申请人提供）：神经母细胞瘤是一种胚胎神经嵴肿瘤，恶性程度很高，对常规治疗反应较差，但肿瘤细胞保留分化能力。 这种癌症对大多数患者来说最终是致命的，因此迫切需要确定新的药物和治疗策略。 我们的长期目标是了解恶性肿瘤与细胞分化状态之间的关系。 细胞表型和N-myc原癌基因的扩增是影响神经母细胞瘤恶性潜能的两个因素。 在细胞系中，N-myc 表达和恶性程度受细胞表型的显着影响。 神经母细胞表达高水平的 N-myc，具有致瘤性，而来自同一亲本细胞系的非神经元 S 型细胞含有明显较低量的 N-myc RNA/蛋白质，并且不具有致瘤性。 这两种细胞类型源自第三种细胞类型，即恶性 I 型干细胞。 此外，实验诱导的细胞表型变化可以直接影响 N-myc 表达，而这种癌蛋白反过来又调节影响细胞生长和恶性肿瘤的特定下游基因。 这些观察结果构成了我们中心假设的基础：细胞分化状态，特别是恶性干细胞表型，以及 N-myc 表达水平直接调节神经母细胞瘤细胞的恶性潜能。 HuD 是一种调节 N-myc 表达的谱系特异性因子，它是一种神经元特异性 RNA 结合蛋白。 HuD 调节 N-myc mRNA 的剪接/稳定性，并且在转染实验中，它会影响细胞 N-myc mRNA 和蛋白质的量。 N-myc 反过来调节巢蛋白，这种神经外胚层中间丝蛋白似乎介导 N-myc 的多种致癌功能。 该提案的两个目标检验了我们假设的不同方面。 目标 #1 的重点是确定 HuD 与 N-nyc mRNA 相互作用的机制，从而调节其表达，作为推论，一个 HuD 等位基因的丢失是否是 N-myc 扩增和发展的关键因素肿瘤的侵袭性。 其次，我们将研究 N-myc 调节巢蛋白的机制以及巢蛋白如何增强细胞的恶性潜能。 目标 2 中提出的研究将 1) 确定肿瘤中 I 型干细胞的相对数量是否与肿瘤分期、侵袭性或无事件生存相关，并可预测疾病进展；2) 分离和表征肿瘤的组成表型。 对具有有利或不利预后的肿瘤细胞的分化状态以及可直接影响细胞分化并从而影响恶性潜力的因素的了解很可能对神经母细胞瘤的治疗具有重要的应用。