DEREGULATION OF ONCOGENE EXPRESSION IN HUMAN TUMORS

我们的长期目标是阐明癌基因激活的机制。 并评估人类肿瘤中基因损伤的可能性 癌基因表达的反式作用调节因子在 这种激活。为此，我们克隆了人c-myc基因以 生成用于定量RNA中myc序列的探针 从多种人类肿瘤中提取。使用这些探测器，我们有 观察到表达增加(高于正常水平的10倍以上 组织)中c-myc基因在肿瘤细胞中的表达 白血病/淋巴瘤和结肠癌患者。关于冒号的研究 癌细胞株已经表明，在表达上调的样本中， MYC被解除管制；即失去正常的细胞周期控制， 基因是结构性表达的。此外，我们还观察到，在 绝大多数病例中，myc基因表达升高。 肿瘤细胞不是由于可检测到的重排或扩增 MYC LOCUS本身。进一步分析这些基因的myc基因座结构 肿瘤将使用克隆和测序技术进行治疗。二 激活的型号类型，由于顺式作用或 反式作用元素，将被测试。为了在以下位置测试更改 Myc基因座本身(顺式作用效应)导致增强 表达，从肿瘤中克隆的myc基因座将被测试转录 将其导入低水平的受体细胞后的活性 内源性myc表达。检测其他基因位点的损伤，这些基因可能 影响myc表达(反式作用效应)，将进行细胞融合 高表达myc的肿瘤细胞和正常细胞之间的关系 Myc表达水平较低。有缺陷的负性作用调控基因 在这项试验中，肿瘤细胞中的等位基因将会被 正常细胞导致杂交瘤中myc的低水平表达 细胞。旨在测试正向作用调节的实验 文中还提出了构成要素。最终，我们希望克隆和研究 以这种方式确定的任何调控基因座的产物。(十)

Our long-range goal is to elucidate mechanisms of oncogene activation in human tumors and to assess the possiblity that genetic lesions in trans-acting regulators of oncogene expression play an important role in this activation. Towards this goal, we have cloned the human c-myc gene to generate probes to be used for quantitation of myc sequences in RNAs prepared from a variety of human tumors. Using these probes, we have observed elevated expression (greater than 10-fold above levels in normal tissue) of the c-myc gene in tumor cells obtained from certain leukemia/lymphoma and colon carcinoma patients. Studies with colon carcinoma cell lines have shown that, in samples with elevated expression, myc is deregulated; i.e., the normal cell cycle control is lost and the gene is constitutively expressed. In addition, we have observed that, in the vast majority of cases, elevated expression of the myc gene in the tumor cells is not due to detectable rearrangements or amplification of the myc locus itself. Further structural analysis of the myc locus in these tumors will be performed using cloning and sequencing technology. Two types of models for the activation, due to either cis-acting or trans-acting elements, will be tested. In order to test for alterations at the myc locus itself (cis-acting effects) which result in enhanced expression, myc loci cloned from tumors will be tested for transcriptional activity after transfection into recipient cells with low levels of endogenous myc expression. To test for lesions at other loci which may affect myc expression (trans-acting effects), cell fusions wil be performed between tumor cells expressing myc at high levels and normal cells having low levels of myc expression. Defective negative acting regulatory genes in the tumor cells would be complemented in this assay by alleles in the normal cells resulting in a low level of myc expression in the hybrid cells. Experiments designed to test for positive acting regulatory elements are also proposed. Ultimately, we would hope to clone and study the products of any regulatory loci identified in this manner. (X)