Molecular basis of reduced albumin synthesis in Morris hepatoma 7777.
Molecular basis of reduced albumin synthesis in Morris hepatoma 7777.
复制标题
Morris 肝癌 7777 中白蛋白合成减少的分子基础。
作者：
T. P. Tse;H. Morris;J. Taylor
采用白蛋白互补DNA （white protein complementary DNA, cDNA）分子杂交和翻译法比较了正常水牛大鼠肝脏和莫里斯肝癌7777中白蛋白mRNA的表达水平。发现白蛋白mRNA占大鼠肝脏含多聚(A) RNA总数的10%，但在莫里斯肝癌7777的情况下减少了大约四倍。在mRNA依赖的无细胞蛋白合成系统中，通过翻译检测到肝癌中白蛋白mRNA活性的等效降低。没有观察到总肝癌多聚(A) RNA的比例增加，这表明肝癌中白蛋白合成确实减少了四倍。与正常肝脏相比，肝癌中白蛋白基因频率没有明显变化。合成了肝脏总RNA和肝癌多聚(A) RNA的互补DNA拷贝，并将其用于同源和异源杂交反应。这些反应的分析表明，肝脏和肝癌的多聚(a)- RNA具有高度的同源性，只是相对序列丰度有所不同。然而，在肝癌中检测到质的差异7777，这与肿瘤转化过程中基因表达控制改变的概念一致。
The level of albumin mRNA in the normal Buffalo rat liver and Morris hepatoma 7777 was compared by molecular hybridization with albumin complementary DNA (cDNA) and translational assays. Albumin mRNA was found to be 10% of the total rat liver poly(A)-containing RNA population but reduced approximately fourfold in the case of Morris hepatoma 7777. An equivalent decrease of albumin mRNA activity in the hepatoma was detected by translation in a mRNA-dependent cell-free protein-synthesizing system. A proportional increase in total hepatoma poly(A)-containing RNA was not observed, indicating that there was a true fourfold reduction of albumin synthesis in the hepatoma. DNA excess hybridization with albumin cDNA did not reveal any apparent change in albumin gene frequency in the hepatoma compared to normal liver. Complementary DNA copies of total liver and hepatoma poly(A)-containing RNA were synthesized and employed in homologous and heterologous hybridization reactions. Analyses of these reactions showed a high degree of homology between the poly(A)-containing RNA of the liver and hepatoma, with some difference in the relative sequence abundancy. However, qualitative differences were detected in hepatoma 7777 consistent with the concept of alterations in the control of gene expression upon neoplastic transformation.