Le Mée S, Chaminade F, Delaporte C, Markovits J, Saucier J M, Jacquemin-Sablon A
Centre National de la Recherche Scientifique UMR 8532, Physico-chimie et Pharmacologie des Macromolécules Biologiques, Institut Gustave Roussy, Villejuif, France.
Mol Pharmacol. 2000 Oct;58(4):709-18. doi: 10.1124/mol.58.4.709.
The new olivacine derivative S16020-2 (NSC-659687) is a DNA topoisomerase II inhibitor endowed with a remarkable antitumor activity against various experimental tumors. In vitro physicochemical properties of this compound, in particular its interaction with DNA and DNA topoisomerase II, were very similar to those of ellipticine derivatives, except for a strictly ATP-dependent mechanism of cleavable complex induction. From the Chinese hamster lung fibroblast cell line DC-3F, a subline resistant to S16020-2, named DC-3F/S16, was selected by adding stepwise increasing concentrations of the drug to the cell growth medium. Whereas DC-3F/9-OH-E cells, a DC-3F subline resistant to 9-hydroxy-ellipticine, are cross-resistant to S16020-2, DC-3F/S16 cells are only very weakly cross-resistant to ellipticine derivatives, indicating that, despite their structural similarity, these compounds may differ in their mechanisms of action. Uptake and efflux rates of S16020-2 were identical in the resistant and the sensitive cells. Topoisomerase IIalpha was expressed at the same level in both sensitive and resistant cells, whereas expression of the beta-enzyme was approximately 50% lower in the resistant cells. Sequencing of both alpha- and beta-isoform cDNAs revealed a point mutation that converts Arg(486) to a Gly in the alpha cDNA, whereas the beta cDNA was not modified. This amino acid substitution in a highly conserved sequence of the enzyme appears to be responsible for the resistance to S16020-2. Comparative analysis of the properties of the ellipticine and S16020-2-resistant cells suggests that S16020-2, which is a DNA intercalator, might also interact with this enzyme amino acid sequence through its side chain.
新型橄榄喜树碱衍生物S16020-2（NSC-659687）是一种DNA拓扑异构酶II抑制剂，对多种实验性肿瘤具有显著的抗肿瘤活性。该化合物的体外物理化学性质，特别是其与DNA和DNA拓扑异构酶II的相互作用，与椭圆玫瑰树碱衍生物非常相似，只是诱导可裂解复合物的机制严格依赖ATP。通过向细胞生长培养基中逐步增加药物浓度，从中国仓鼠肺成纤维细胞系DC-3F中筛选出对S16020-2耐药的亚系，命名为DC-3F/S16。对9-羟基椭圆玫瑰树碱耐药的DC-3F亚系DC-3F/9-OH-E细胞对S16020-2具有交叉耐药性，而DC-3F/S16细胞对椭圆玫瑰树碱衍生物的交叉耐药性非常弱，这表明尽管这些化合物结构相似，但它们的作用机制可能不同。S16020-2在耐药细胞和敏感细胞中的摄取和外排速率相同。拓扑异构酶IIα在敏感细胞和耐药细胞中的表达水平相同，而β酶在耐药细胞中的表达约低50%。α和β同工型cDNA测序显示，α cDNA中一个点突变将Arg(486)转换为Gly，而β cDNA未发生修饰。该酶高度保守序列中的这种氨基酸取代似乎是对S16020-2耐药的原因。对椭圆玫瑰树碱和S16020-2耐药细胞特性的比较分析表明，作为DNA嵌入剂的S16020-2也可能通过其侧链与该酶氨基酸序列相互作用。
