NEUROFIBROMATOSIS-1 MUTATIONS AND NEUROBLASTOMA

神经纤维瘤病1型(NF1)是最常见的常染色体病之一 人类的显性疾病。NF1患者通常发展为良性 神经纤维瘤和几种恶性神经疾病的风险增加 系统肿瘤。最近克隆了与NF1有关的基因，并 编码一种蛋白，可以激活p2lras的GTP酶。我们有 发现NF1突变在神经脊来源的肿瘤中很常见， 神经母细胞瘤，与NF1无关。频度的检测 神经母细胞瘤中的NF1突变表明这些突变对 与这种肿瘤的发展有关。NF1缺陷性神经母细胞瘤与 NF1肿瘤细胞株ras-GTP几乎没有增加(如果有的话) 级别。为了跟进这些发现，我们提出了几个实验。 我们将解决的一个重要问题是，NF1是否是一个 神经母细胞瘤肿瘤抑制因子。为了确定NF1基因突变是否发生在 原发神经母细胞瘤我们将检测患者的血液和肿瘤样本 神经母细胞瘤。分析NF1基因是否为神经母细胞瘤 肿瘤抑制因子，我们将在缺陷细胞中重建表达 并检测它们在体外和体内的生长潜力。 NF1缺陷细胞系将被用来解决两个问题。第一, 我们将跟进我们的发现，与NF1恶性肿瘤细胞不同， NF1缺陷的神经母细胞瘤只有低水平的ras-GTP。其次，我们 将分析NF1中是否有任何RAS中介的过程异常 缺乏细胞。在这些实验中，我们将分析被激发的配体 C-raf-1和MAP蛋白激酶以及c-fos基因的激活 归纳法。我们认为，这两种方法都有重要的意义 有可能帮助确定NF1的功能，这是下一个 这一领域的挑战。

Neurofibromatosis type 1 (NF1) is one of the most common autosomal dominant disorders of man. Patients with NF1 often develop benign neurofibromas and are at increased risk for several malignant nervous system tumors. The gene responsible for NF1 has recently been cloned and shown to encode a protein that can activate the GTPase of p2lras. We have found that NF1 mutations are frequent in a neural crest derived tumor, neuroblastoma, which is not associated with NF1. The detection of frequent NF1 mutations in neuroblastomas suggests that these mutations contribute to the development of this tumor. NF1 deficient neuroblastomas differ from NF1 tumor cell lines in showing little, if any, increase in ras-GTP levels. To follow up on these findings we propose several experiments. An important question that we will address is whether NF1 is a neuroblastoma tumor suppressor. To determine if NF1 mutations occur in primary neuroblastomas we will test blood and tumor samples from patients with neuroblastoma. To analyze whether the NF1 gene is a neuroblastoma tumor suppressor, we will reestablish expression in the deficient cell lines and test their in vitro and in vivo growth potential. The NF1 deficient cell lines will be used to address two questions. First, we will follow up on our finding that, unlike NF1 malignant tumor cells, NF1 deficient neuroblastomas have only low levels of ras-GTP. Secondly, we will analyze whether any ras-mediated processes are abnormal in NF1 deficient cells. In these experiments we shall analyze ligand stimulated activation of the c-raf-1 and MAP protein kinases, as well as c-fos mRNA induction. We believe that both these approaches have significant potential to help determine the function of NF1, which is the next challenge in this field.