Barthomeuf Chantal, Grassi Jérôme, Demeule Michel, Fournier Chantal, Boivin Dominique, Béliveau Richard
UMR-INSERM U-484, Laboratoire de Pharmacognosie et Biotechnologies, Faculté de Pharmacie, Université d'Auvergne, Place H. Dunant, 63001 Clermont-Fd Cedex, France.
Cancer Chemother Pharmacol. 2005 Aug;56(2):173-81. doi: 10.1007/s00280-004-0914-y. Epub 2005 Apr 12.
Overexpression of P-glycoprotein (Pgp) encoded by the MDR1 gene is one of the major obstacles to successful cancer chemotherapy. The goal of this study was to evaluate if, among other natural coumarins, cnidiadin, a furanocoumarin present in traditional Chinese medications and in a spice commonly used in Greek food, inhibits Pgp transport activity and has the potential to reverse MDR1 multidrug resistance.
Using MDR1-transfected Madin-Darby canine kidney (MDCK-MDR1) cells as a model of cells expressing the human MDR1 phenotype, and verapamil or CsA or both as positive control, we tested the capacity of six natural coumarins (umbelliferone, esculin, esculetin, cnidiadin, angelicin and psoralen) to induce the accumulation of rhodamine-123 (R-123) and [3H]-vinblastine ([3H]-VBL) and to modulate the photolabeling of Pgp by SDZ 212-122, a diazirin cyclosporin A. The growth-inhibitory effect of cnidiadin and its capacity to enhance the cell toxicity of vinblastine (VBL) or vincristine (VCR) was then evaluated by the WST-1 assay in two cell lines overexpressing Pgp (MDCK-MDR1 and vincristine-resistant KB/VCR).
Cnidiadin was the only tested coumarin capable of significantly accumulating R-123 and [3H]-VBL and inhibiting Pgp photolabeling in MDCK-MDR1 cells. The dose-dependent increase in [3H]-VBL uptake (IC50 26.5 microM) induced by cnidiadin in the dose range 1-100 microM correlated with inhibition of Pgp photolabeling. At 10 microM cnidiadin inhibited photolabeling by 59% and sensitized both MDCK-MDR1 and KB/VCR cells to vinca alkaloids.
Cnidiadin is a cytotoxic agent capable in vitro of competitively inhibiting the binding and efflux of drug by Pgp and of enhancing the cell toxicity of vinca alkaloids in two cell lines (MDCK-MDR1 and mutant human carcinoma KB/VCR) overexpressing Pgp. This suggests that diet or traditional preparation containing cnidiadin may contribute to the reversal of MDR1 multidrug resistance and may affect the bioavailability of Pgp substrates orally administered. However, due to its cell toxicity, clinical interest in cnidiadin as a chemosensitizer appears to be limited.
多药耐药基因1（MDR1）编码的P-糖蛋白（Pgp）过表达是癌症化疗成功的主要障碍之一。本研究的目的是评估在其他天然香豆素中，蛇床子素（一种存在于中药和希腊食物常用香料中的呋喃香豆素）是否抑制Pgp转运活性，并具有逆转MDR1介导的多药耐药的潜力。
以转染MDR1的Madin-Darby犬肾细胞（MDCK-MDR1）作为表达人MDR1表型的细胞模型，以维拉帕米或环孢素A或两者作为阳性对照，我们测试了六种天然香豆素（伞形花内酯、七叶苷、七叶亭、蛇床子素、白芷素和补骨脂素）诱导罗丹明123（R-123）和[3H]长春碱（[3H]-VBL）蓄积以及调节Pgp经二氮杂环庚因环孢素A（SDZ 212-122）进行光标记的能力。然后通过WST-1检测法在两种过表达Pgp的细胞系（MDCK-MDR1和长春新碱耐药的KB/VCR）中评估蛇床子素的生长抑制作用及其增强长春碱（VBL）或长春新碱（VCR）细胞毒性的能力。
蛇床子素是唯一能够使R-123和[3H]-VBL在MDCK-MDR1细胞中显著蓄积并抑制Pgp光标记的受试香豆素。在1-100μM剂量范围内，蛇床子素诱导的[3H]-VBL摄取量的剂量依赖性增加（IC50为26.5μM）与Pgp光标记的抑制相关。在10μM时，蛇床子素抑制光标记达59%，并使MDCK-MDR1和KB/VCR细胞对长春花生物碱敏感。
蛇床子素是一种细胞毒性药物，在体外能够竞争性抑制Pgp与药物的结合及药物外排，并增强两种过表达Pgp的细胞系（MDCK-MDR1和突变的人KB/VCR癌细胞）中长春花生物碱的细胞毒性。这表明含有蛇床子素的饮食或传统制剂可能有助于逆转MDR1介导的多药耐药，并可能影响口服给予的Pgp底物的生物利用度。然而，由于其细胞毒性，蛇床子素作为化学增敏剂的临床应用前景似乎有限。
