MOLECULAR MECHANISMS OF DIFFERENTIATION IN NEUROBLASTOMA

神经母细胞瘤（NB）是一种起源于神经嵴的恶性肿瘤， 最常见的儿童颅外实体瘤。 自发性分化 良性节细胞神经瘤中偶见NB。 这 这一过程涉及神经母细胞表型的丧失和 类似于成熟的神经节神经元的细胞。 即使在不需要 完全成熟至良性节细胞神经瘤，组织学程度 成熟直接影响肿瘤的临床行为， 因此具有临床重要性。 因为大多数人类神经母细胞瘤细胞 品系经历形态和生化分化， 包括视黄酸（RA）在内的多种药物， 用于检查NB分化。 的重点 研究将是分离和表征NB中的基因， 在处理后180分钟诱导或下调表达 通过差异筛选从LA-N-5构建的cDNA文库， 用放射性标记的cDNA探针用RA处理NB细胞180分钟 由未处理和RA处理的人NB细胞制备（LA-N-5. 通过欺诈- 集中在表达的早期变化，可能是必要的基因， 是分化过程的实现而不是基因 其产品与特定的神经功能相关联， 可以分离分化的细胞。 其他NB细胞系，其中许多 已在本实验室建立并鉴定，将随后- 用分化相关序列探测以确定是否 这些克隆在RA处理后在其它扩增的N-myc中表达， 未放大的线 此外，这些基因在原发性 表达水平与肿瘤程度的关系 组织学分化和临床结果将被确定。 最后，将这些序列整合到表达载体中， 导入人NB细胞。 表达的生物学效应 然后分析受体细胞中的克隆。 了解 NB分化的分子机制可能提供对NB分化的深入了解。 与NB相关的分化调节改变。

Neuroblastoma (NB), a malignant neoplasm of neural crest origin, is the most common extracranial solid tumor in children. Spontaneous differentia- tion of NB to benign ganglioneuroma occurs occasionally in vivo. This process involves the loss of the neuroblast phenotype and the appearance of cells resembling mature ganglionic neurons. Even in NBs which do not mature completely to benign ganglioneuromas, the degree of histologic maturation directly influences the clinical behavior of the tumor and is, therefore, of clinical importance. Because most human neuroblastoma cell lines undergo morphologic and biochemical differentiation in response to a variety of gents including retinoic acid (RA), an excellent in vitro model for the examination of NB differentiation is available. The focus of this study will be to isolate and characterize the genes in NBs in which expression is either induced or down-regulated 180 minutes after treatment with RA by differentially screening a cDNA library constructed from LA-N-5 NB cells treated with RA for 180 minutes with radiolabeled cDNA probes prepared from untreated and RA-treated human NB cells (LA-N-5. By con- centrating on early changes in expression, genes which may be necessary for the implementation of the differentiation process rather than the genes whose products are associated with the specific neural features of the differentiated cell may be isolated. Other NB cell lines, many of which have been established an characterized in this laboratory, will subsequent- ly be probed with the differentiation related sequences to determine if these clones are expressed after RA treatment in other N-myc amplified and unamplified lines. In addition, the expression of these genes in primary tumors and the relationship between the levels of expression and the degree of histologic differentiation, and clinical outcome will be determined. Finally, these sequences will be incorporated into expression vectors and introduced back into human NB cells. Biological effects of the expressed clones in recipient cells will then be analyzed. Understanding the molecular mechanisms of NB differentiation may provide insight into the altered regulation of differentiation associated with NB.