Ferguson P J, Cass C E
Cancer Res. 1985 Nov;45(11 Pt 1):5480-8.
Differential toxicity of vincristine and vinblastine against cells of a cloned subline of human promyelocytic leukemia (HL-60/Cl) was dependent on exposure conditions. During continuous exposures of 48 h, vincristine and vinblastine were equitoxic with drug concentrations that inhibited proliferation rates by 50% of 7.6 and 8.1 nM, respectively. When cells were subjected to 4-h exposures and transferred to drug-free medium, the drug concentration of vinblastine that inhibited proliferation rates by 50% (1.1 microM) was significantly greater than that of vincristine (41 nM). Analysis by flow cytometry of the effects of equitoxic drug exposures on cell-cycle progression suggested that vincristine and vinblastine acted by the same mechanism (G2-M phase inhibition). [3H]Vincristine and [3H]vinblastine were bound to serum proteins in growth medium to the same extent (25%) over a wide range of concentrations, and the amounts of "free" extracellular drug did not decrease during prolonged exposures. Analysis by high-performance liquid chromatography of extracts of cultures incubated with growth-inhibitory concentrations of [3H]vincristine or [3H]vinblastine indicated little, if any, metabolism of either drug by cells or culture fluids; after 24 h, 85-95% of radioactivity was recovered from cells or growth medium as unchanged vincristine or vinblastine. At concentrations from 6 nM to 6 microM, vinblastine entered cells rapidly, reaching maximum levels within 0.5-2 h, and the relationship between maximal cell-associated drug and extracellular free vinblastine was linear. Although uptake of vincristine was slower than that of vinblastine, the cellular content of vincristine reached that of vinblastine during prolonged (12-24 h) exposures, and the amounts of cell-associated drug, relative to extracellular drug concentrations, indicated considerable "concentrative" accumulation (intra: extracellular ratios, greater than 100). When drug exposures were ended by transfer of cells to drug-free medium, vinblastine was released from cells more rapidly and to a greater extent than vincristine, independent of whether exposures were 4 or 24 h. Rates of uptake and release of vinblastine (50 nM) were unaffected by depletion of cellular adenosine triphosphate, suggesting that rapid release was not mediated by an energy-dependent efflux system.
长春新碱和长春花碱对人早幼粒细胞白血病克隆亚系（HL-60/Cl）细胞的毒性差异取决于暴露条件。在48小时的持续暴露期间，长春新碱和长春花碱具有同等毒性，抑制增殖率50%的药物浓度分别为7.6 nM和8.1 nM。当细胞接受4小时暴露并转移至无药培养基时，抑制增殖率50%的长春花碱药物浓度（1.1 microM）显著高于长春新碱（41 nM）。通过流式细胞术分析同等毒性药物暴露对细胞周期进程的影响表明，长春新碱和长春花碱作用机制相同（G2-M期抑制）。[3H]长春新碱和[3H]长春花碱在生长培养基中与血清蛋白的结合程度相同（25%），在很宽的浓度范围内，长时间暴露期间“游离”细胞外药物的量并未减少。通过高效液相色谱分析与抑制生长浓度的[3H]长春新碱或[3H]长春花碱一起孵育的培养物提取物表明，细胞或培养液对这两种药物几乎没有代谢（如果有的话）；24小时后，85-95%的放射性以未改变的长春新碱或长春花碱形式从细胞或生长培养基中回收。在6 nM至6 microM的浓度范围内，长春花碱迅速进入细胞，在0.5-2小时内达到最高水平，最大细胞相关药物与细胞外游离长春花碱之间的关系呈线性。虽然长春新碱的摄取比长春花碱慢，但在长时间（12-24小时）暴露期间，长春新碱的细胞含量达到长春花碱的水平，相对于细胞外药物浓度，细胞相关药物的量表明有相当程度的“浓缩”积累（细胞内：细胞外比率大于100）。当通过将细胞转移至无药培养基来结束药物暴露时，长春花碱比长春新碱从细胞中释放得更快且程度更大，这与暴露是4小时还是24小时无关。长春花碱（50 nM）的摄取和释放速率不受细胞三磷酸腺苷耗竭的影响，这表明快速释放不是由能量依赖性外排系统介导的。
