ONCOGENES-ONCOGENE PRODUCTS IN RADIATION-INDUCED TUMORS

本项目的目的是评估癌基因 表达作为辐射致癌作用的一个步骤发生。 这种可能性 正在使用大鼠甲状腺癌发生模型进行评估， 甲状腺上皮对致癌作用的高度敏感性 电离辐射。 显性转化癌基因的鉴定 辐射诱发的腺瘤和癌细胞的基因组正在 其特征在于，并与从正常甲状腺的DNA中分离的那些进行比较， 细胞和自发性甲状腺肿瘤的细胞。 同样，mRNA 与上述癌基因相关的转录物和蛋白质产物 上面正在分析。 它们的结构和功能 大分子将与那些与已知的 逆转录病毒癌基因。 放射性甲状腺肿瘤和自发性甲状腺肿瘤的细胞DNA 以及正常甲状腺细胞中的蛋白质都受到限制 核酸内切酶消化和Southern印迹分析，利用完整的 一组缺口翻译的逆转录病毒癌基因探针。 使用从辐射诱导的甲状腺癌中分离的DNA， 能够识别rask、myc和abl中的突变和DNA重排 致癌基因 这种DNA也能够在细胞中转染NIH/3 T3细胞。 DNA介导的基因转移测定。 目前，分子克隆和 测序技术被用来定位显性转化 癌基因 一旦受影响的癌基因被分离出来， 将在转染测定中使用以下方法测试协同效应： 携带这些癌基因cDNA拷贝的重组DNA分子， 真核表达载体。 利用北方印迹分析来确定 这三种癌基因在正常组织和肿瘤组织中的表达。 的cDNA拷贝 受影响的癌基因被克隆到细菌质粒中， 癌基因特异性蛋白质正在使用特异性抗血清进行表征 针对myc和rask蛋白产物。 这些蛋白质被 其特征在于定位，分子量， 蛋白激酶活性、GTP酶和GTP结合活性。 这些参数 将与已知的逆转录病毒转化蛋白进行比较。

The goal of this project is to evaluate the hypothesis that oncogene expression occurs as a step in radiation carcinogenesis. This possibility is being evaluated using a rat thyroid carcinogenesis model capitolizing on the exquisite sensitivity of thyroid epithelium to the carcinogenic effects of ionizing radiation. Dominant transforming oncogenes identified in the genome of cells from radiation-induced adenomas and carcinomas are being characterized and compared to those isolated from the DNA of normal thyroid cells and cells from spontaneous thyroid tumors. Likewise, the mRNA transcripts and protein products associated with the oncogenes mentioned above are being analyzed. The structure and function of these macromolecules will be compared with those associated with the known retroviral oncogenes. The cellular DNA from radiation-induced and spontaneous thyroid tumors as well as from normal thyroid cells are being subjected to restriction endonuclease digestion and Southern blot analysis utilizing a complete battery of nick translated retroviral oncogene probes. Using DNA isolated from a radiation-induced thyroid carcinoma we have been able to identify mutations and DNA rearrangements in the rask, myc, and abl oncogenes. This DNA is also capable of transfecting NIH/3T3 cells in the DNA mediated gene transfer assays. At present molecular cloning and sequencing techniques are being used to localize the dominant transforming oncogene. Once the effected oncogenes are isolated their individual and collaborative effects will be tested in the transfection assays using recombinant DNA molecules harboring cDNA copies of these oncogenes in eukaryotic expression vectors. Northern blot analysis is being utilized to determine the level of expression of these 3 oncogenes in normal and tumor tissue. cDNA copies of the affected oncogenes are being cloned in bacterial plasmids and oncogene-specific proteins are being characterized using specific antisera against myc and rask protein products. These proteins are being characterized with respect to localization, molecular weight, protein-kinase activity, GTPase and GTP-binding activity. These parameters will be compared with those of known retroviral transforming proteins.