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， 人类肿瘤，并评估遗传病变的可能性， 癌基因表达的反式作用调节因子在 这个激活。 为了实现这一目标，我们克隆了人类c-myc基因， 生成用于定量RNA中myc序列的探针 从各种人类肿瘤中提取 利用这些探测器， 观察到表达升高（高于正常对照组水平10倍以上）， 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。 结肠研究 癌细胞系已经显示，在具有升高表达的样品中， myc被解除调节;即，正常的细胞周期控制丧失， 基因组成型表达。 此外，我们注意到，在 在绝大多数情况下，myc基因的表达升高， 肿瘤细胞不是由于可检测到的重排或扩增， Myc locus本身。 进一步的myc基因座的结构分析， 肿瘤将使用克隆和测序技术进行。 两 激活的模型类型，由于顺式作用或 反式作用元件，将被测试。 为了测试在 myc基因座本身（顺式作用效应）导致增强的 从肿瘤克隆的myc基因座将被测试转录水平。 在转染到具有低水平的 内源性myc表达。 检测其他部位的病变， 影响myc表达（反式作用），将进行细胞融合 在高水平表达myc的肿瘤细胞和正常细胞之间， 低水平的myc表达。 缺陷性负作用调控基因 在该测定中，肿瘤细胞中的等位基因将被肿瘤细胞中的等位基因补充。 正常细胞导致杂合体中myc表达水平低 细胞 设计用于测试正作用调节的实验 还提出了要素。 最终，我们希望克隆和研究 以这种方式鉴定的任何调节基因座的产物。 （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)