Division of Oncology, Department of Medicine, Stanford University School of Medicine, CCSR North 1120, 269 Campus Drive, Stanford, CA, 94305-5151, USA.
Sanofi R&D, Frankfurt, Germany.
Cancer Chemother Pharmacol. 2018 Jun;81(6):1095-1103. doi: 10.1007/s00280-018-3572-1. Epub 2018 Apr 19.
The primary aim of this study was to determine cabazitaxel's affinity for the ABCB1/P-glycoprotein (P-gp) transporter compared to first-generation taxanes.
We determined the kinetics of drug accumulation and retention using [C]-labeled taxanes in multidrug-resistant (MDR) cells. In addition, membrane-enriched fractions isolated from doxorubicin-selected MES-SA/Dx5 cells were used to determine sodium orthovanadate-sensitive ATPase stimulation after exposure to taxanes. Custom [H]-azido-taxane analogues were synthesized for the photoaffinity labeling of P-gp.
The maximum intracellular drug concentration was achieved faster with [C]-cabazitaxel (5 min) than [C]-docetaxel (15-30 min). MDR cells accumulated twice as much cabazitaxel than docetaxel, and these levels could be restored to parental levels in the presence of the P-gp inhibitor PSC-833 (valspodar). Efflux in drug-free medium confirmed that MDR cells retained twice as much cabazitaxel than docetaxel. There was a strong association (r = 0.91) between the degree of taxane resistance conferred by P-gp expression and the accumulation differences observed with the two taxanes. One cell model expressing low levels of P-gp was not cross-resistant to cabazitaxel while demonstrating modest resistance to docetaxel. Furthermore, there was a 1.9 × reduction in sodium orthovanadate-sensitive ATPase stimulation resulting from treatment with cabazitaxel compared to docetaxel. We calculated a dissociation constant (Kd) value of 1.7 µM for [H]-azido-docetaxel and ~ 7.5 µM for [H]-azido-cabazitaxel resulting in a 4.4 × difference in P-gp labeling, and cold docetaxel was a more effective competitor than cabazitaxel.
Our studies confirm that cabazitaxel is more active in ABCB1(+) cell models due to its reduced affinity for P-gp compared to docetaxel.
本研究的主要目的是确定卡巴他赛与 ABCB1/P-糖蛋白（P-gp）转运蛋白的亲和力，与第一代紫杉烷类药物进行比较。
我们使用多药耐药（MDR）细胞中的[C]标记紫杉烷类药物来确定药物积累和保留的动力学。此外，还使用阿霉素选择的 MES-SA/Dx5 细胞分离的膜富集部分来确定紫杉烷类药物暴露后对钠钒酸盐敏感的 ATP 酶刺激。合成了定制的[H]叠氮taxane 类似物，用于 P-gp 的光亲和标记。
[C]-卡巴他赛（5 分钟）达到最大细胞内药物浓度的速度快于[C]-多西他赛（15-30 分钟）。MDR 细胞积累的卡巴他赛是多西他赛的两倍，在 P-gp 抑制剂 PSC-833（valspodar）存在的情况下，这些水平可以恢复到亲本水平。无药物介质中的外排证实，MDR 细胞保留的卡巴他赛是多西他赛的两倍。紫杉烷类药物的 P-gp 表达赋予的耐药程度与两种紫杉烷类药物观察到的积累差异之间存在很强的相关性（r=0.91）。一个表达低水平 P-gp 的细胞模型对卡巴他赛没有交叉耐药性，但对多西他赛表现出适度的耐药性。此外，与多西他赛相比，卡巴他赛处理导致钠钒酸盐敏感的 ATP 酶刺激减少了 1.9 倍。我们计算出[H]-叠氮多西他赛的解离常数（Kd）值为 1.7µM，[H]-叠氮卡巴他赛的 Kd 值为~7.5µM，导致 P-gp 标记差异 4.4 倍，而冷多西他赛是比卡巴他赛更有效的竞争物。
我们的研究证实，与多西他赛相比，卡巴他赛对 ABCB1（+）细胞模型的活性更高，因为其对 P-gp 的亲和力降低。
