Regulation of the N-myc oncogene in neuroblastoma

描述：(申请人提供)本提案的目标是确定 神经母细胞瘤细胞N-myc转录下调机制的研究 维甲酸(RA)。RA对N-myc的转录作用是通过一种 粗略定义的启动子区域(RA响应区，或RARR)。这些 研究将检验这一假设，即表达N-myc的细胞中的RARR突变 导致转录因子的补体或构型改变 与启动子结合，导致不能下调N-myc RA处理后，细胞对RA诱导的表型抵抗 分化，以及对RA缺乏临床反应。在第一个具体的 目的、瞬时转染法和DNA凝胶移位、交联和足迹 分析将用于鉴定和表征启动子序列和 N-myc基础转录所需的DNA结合蛋白，ITS RA的下调，及其在RA抵抗细胞中的结构性表达。在……里面 第二个具体目标是阻断RA的突变的生物学效应 诱导的启动子下调将用STRATE进行测试 含有野生型或突变启动子驱动的N-myc的转染体。 第三个具体目标将决定RARR的临床意义。 通过比较它们在RA敏感和耐药细胞中的发生率来确定突变 在确诊时和RA治疗后复发后获得的肿瘤对中， 以及在高风险和低风险肿瘤中。诊断时存在RARR突变 也会与高危人群的存活率下降相关 神经母细胞瘤患者接受维甲酸治疗。RA目前是唯一有效的 生物调节剂在神经母细胞瘤治疗中的应用 残留病。从这些调查中获得的结果将提供 以分子为基础的机械基础，最终将允许 与类风湿关节炎治疗有关的患者的预后。这些数据将 帮助确定RA耐药患者参加其他试验的候选患者 生物活性物质。最终，对癌基因调控的理解 将促进未来组合差异化的合理发展 神经母细胞瘤的治疗，即使在诱导过程中也可能有效 对抗巨大的疾病。

DESCRIPTION: (provided by applicant) The goal of this proposal is to identify the mechanism of N-myc transcriptional downregulation in neuroblastoma cells by retinoic acid (RA). RA exerts its transcriptional effects on N-myc through a roughly defined region of the promoter (RA response region, or RARR). These studies will test the hypothesis that RARR mutations in N-myc expressing cells leads to alteration of the complement or configuration of transcription factors that bind to the promoter, resulting in the inability to downregulate N-myc after RA treatment, the phenotypic resistance of cells to RA-induced differentiation, and the lack of clinical response to RA. In the first specific aim, transient transfections and DNA gel shift, cross linking, and footprinting analyses will be used to identify and characterize the promoter sequences and DNA binding proteins necessary for basal N-myc transcription, its downregulation by RA, and its constitutive expression in RA resistant cells. In the second specific aim, the biological effects of mutations that block the RA induced downregulation of the promoter will be tested using stable transfectants containing N-myc driven by either wild type or mutated promoters. The third specific aim will determine the clinical significance of RARR mutations by comparing their incidence in RA sensitive and resistant cell lines, in tumor pairs obtained at diagnosis and after relapse post-RA therapy, and in high and low risk tumors. The presence of RARR mutations at diagnosis will also be correlated with decreased survival in a population of high-risk neuroblastoma patients treated with RA. RA is currently the only effective biologic modifier for the therapy of neuroblastoma patients with minimal residual disease. Results obtained from these investigations will provide a molecular-based, mechanistic foundation that will allow eventual prognostication of patients with respect to treatment with RA. Such data will aid in identifying RA-resistant patient candidates for trials of other biologically active agents. Ultimately, an understanding of oncogene regulation will facilitate the future rational development of combination differentiation therapy of neuroblastoma, which might be effective even in the induction setting against bulky disease.