Lupi Monica, Matera Giada, Branduardi Davide, D'Incalci Maurizio, Ubezio Paolo
Biophysics Unit, Laboratory of Anticancer Pharmacology, Department of Oncology, Istituto di Ricerche Farmacologiche Mario Negri, Milano, Italy.
Cancer Res. 2004 Apr 15;64(8):2825-32. doi: 10.1158/0008-5472.can-03-3810.
Topotecan (TPT) is a topoisomerase I inhibitor, and like the other drugs of this family, it is believed to act in a specific way on cells in S phase at the time of treatment. Exploiting a new method, coupling a particular experimental plan with computer simulation, a complete quantitative study of the time dependence and dose dependence of the activity of cell cycle controls has become feasible, and the overall scenario of events after treatment can be reconstructed in detail. We were able to demonstrate that the response of an ovarian cancer cell line to 1 h of treatment with TPT is not limited to inhibition of DNA synthesis, leading to cell death, but involves G(1) and G(2)-M checkpoints. G(1) and G(2)-M block, recycling, and death follow specific dose-dependent kinetics, lasting no less than 3 days after treatment. We also found that cells treated outside S phase contribute significantly to the overall activity. The utility of this analysis was demonstrated by reproducing more complex treatment schemes in which low TPT concentrations were applied for 1 h three times at 24-h intervals. In this case, the simulation clarified the origin of the auto-potentiation observed with repeated 0.2 micro M treatments, in which the cytotoxicity, particularly against S-phase cells, was higher than the cytotoxicity in cells treated with 10 micro M only once. We believe that this approach will help us to understand the complexity and heterogeneity of the response of a cell population to a drug challenge and could help us to establish the rationale for drug scheduling or drug combinations.
拓扑替康（TPT）是一种拓扑异构酶I抑制剂，与该家族的其他药物一样，据信在治疗时对处于S期的细胞以特定方式起作用。利用一种新方法，即将特定的实验方案与计算机模拟相结合，对细胞周期调控活性的时间依赖性和剂量依赖性进行完整的定量研究已成为可能，并且可以详细重建治疗后事件的总体情况。我们能够证明，一种卵巢癌细胞系对TPT 1小时治疗的反应不仅限于抑制DNA合成并导致细胞死亡，还涉及G(1)和G(2)-M检查点。G(1)和G(2)-M阻滞、循环和死亡遵循特定的剂量依赖性动力学，在治疗后持续不少于3天。我们还发现，在S期之外处理的细胞对总体活性有显著贡献。通过重现更复杂的治疗方案（其中低浓度TPT以24小时间隔应用1小时，共三次），证明了这种分析的实用性。在这种情况下，模拟阐明了用0.2微摩尔重复处理时观察到的自增强作用的起源，其中细胞毒性，特别是对S期细胞的细胞毒性，高于仅用10微摩尔处理一次的细胞的细胞毒性。我们相信，这种方法将帮助我们理解细胞群体对药物挑战反应的复杂性和异质性，并有助于我们确定药物给药方案或药物组合的基本原理。
