Stimulation of gene transfer efficiency by treatment of human cells with topoisomerase II inhibitors

在哺乳动物细胞中，非同源重组是修复DNA双链断裂的主要途径。我们已经证明，DNA拓扑异构酶II抑制剂能够通过非同源重组增强外源DNA的随机整合。由于这种增强可能是由于稳定的DNA链断裂，我们研究了放射性抗肿瘤药物博来霉素对非同源重组的影响。我们发现博来霉素极大地增强了转染质粒进入人细胞的随机整合。此外，我们分析了拓扑异构酶II抑制剂处理和未处理培养的克隆中转染DNA与人类染色体之间的整合连接，以及在转染DNA与人类染色体之间的整合连接中发现的插入DNA的特征。这些研究将有助于通过非同源重组和开发更高效率的转染方案来理解DNA整合事件。

In mammalian cells, nonhomologous recombination is a predominant pathway to repair DNA double-strand breaks. We have shown that DNA topoisomerase II inhibitors are capable of enhancing random integration of foreign DNA via nonhomologous recombination. Since this enhancement is likely due to stabilized DNA strand breaks, we examined the effect of radiomineric antitumor drug, bleomycin, on nonhomologous recombination. We found that bleomycin greatly enhances the random integration of transfected plasmids into human cells. Also, we analyzed the integration junctions between transfected DNA and human chromosomes in clones derived from topoisomerase II inhibitor-treated and-untreated cultures as well as the characterization of inserted DNA found in integration junctions between transfected DNA and human chromosomes. These studies will facilitate the understanding of DNA integration events through nonhomologous recombination and the development of transfection protocols with higher efficiencies.