Prost S, Riou G
Laboratory of Clinical and Molecular Pharmacology, Institut Gustave Roussy, Villejuif, France.
Biochem Pharmacol. 1994 Aug 30;48(5):975-84. doi: 10.1016/0006-2952(94)90368-9.
N417/AMSA cells, about 80-fold resistant to mAMSA [4'-(9-acridinylamino)-methanesulfon-m-anisidide], were obtained by serial passages of the parental human small cell lung carcinoma NCI-N417 (N417/p) in stepwise drug concentrations. The N417/AMSA cells were found to be 114-, 100-, and 9-fold cross-resistant to the topoisomerase II (Topo II) inhibitors VM26, VP16 and Doxorubicin (DXR); they showed a 2-fold decrease in Topo II activity. Interestingly, N417/AMSA cells which exhibited a 3-fold increase in topoisomerase I (Topo I) activity were 28-fold cross-resistant to camptothecin (CPT), a specific inhibitor of Topo I. In order to investigate the cellular mechanisms leading to the development of resistance, the effects of mAMSA and CPT on parental and resistant cell lines were analysed by alkaline elution. A decrease in DNA single-strand breaks (DNA-SSB) was observed in N417/AMSA cells treated with mAMSA or CPT compared to parental cells. Similar differences were obtained in isolated nuclei, suggesting that no modification of mAMSA and CPT accumulation occurred in resistant cells. Topo I was purified from N417/p (Topo I/p) and N417/AMSA (Topo I/AMSA) cells in the exponential phase of growth, and the inhibitory effects of CPT on relaxation activities were determined. Topo I/AMSA was found to be about 7-fold less sensitive to CPT than Topo I/p, suggesting the possible involvement of a mutation outside the gene region sequenced (codons 420 to 642) or post-translational modifications of the Topo I enzyme. These data indicate that increased Topo I activity cannot be related to CPT resistance, and suggest that mAMSA can generate multiple cellular modifications which may be involved in resistance to various drugs.
N417/AMSA细胞对mAMSA（4'-(9-吖啶基氨基)-甲磺酰间茴香胺）具有约80倍的抗性，它是通过将亲代人小细胞肺癌NCI-N417（N417/p）在逐步增加的药物浓度中连续传代获得的。发现N417/AMSA细胞对拓扑异构酶II（Topo II）抑制剂VM26、VP16和阿霉素（DXR）具有114倍、100倍和9倍的交叉抗性；它们的Topo II活性降低了2倍。有趣的是，拓扑异构酶I（Topo I）活性增加了3倍的N417/AMSA细胞对Topo I的特异性抑制剂喜树碱（CPT）具有28倍的交叉抗性。为了研究导致抗性产生的细胞机制，通过碱性洗脱分析了mAMSA和CPT对亲代和抗性细胞系的影响。与亲代细胞相比，在用mAMSA或CPT处理的N417/AMSA细胞中观察到DNA单链断裂（DNA-SSB）减少。在分离的细胞核中也获得了类似的差异，这表明抗性细胞中mAMSA和CPT的积累没有发生改变。在生长指数期从N417/p（Topo I/p）和N417/AMSA（Topo I/AMSA）细胞中纯化Topo I，并测定CPT对松弛活性的抑制作用。发现Topo I/AMSA对CPT的敏感性比Topo I/p低约7倍，这表明可能在测序的基因区域（密码子420至642）之外发生了突变，或者Topo I酶发生了翻译后修饰。这些数据表明Topo I活性增加与CPT抗性无关，并表明mAMSA可以产生多种细胞修饰，这些修饰可能与对各种药物的抗性有关。
