Bijman Marcel N A, van Nieuw Amerongen Geerten P, Laurens Nancy, van Hinsbergh Victor W M, Boven Epie
Department of Medical Oncology, Vrije Universiteit Medical Center, De Boelelaan 1117, 1081 HV Amsterdam, the Netherlands.
Mol Cancer Ther. 2006 Sep;5(9):2348-57. doi: 10.1158/1535-7163.MCT-06-0242.
Conventional anticancer agents may display antiangiogenic effects, but the underlying mechanism is poorly understood. We determined the antiangiogenic properties of cisplatin, doxorubicin, and the microtubule-targeting agents docetaxel, epothilone B, and vinblastine at concentrations not affecting cell proliferation. We also assessed tubulin and actin morphology and the activity of two key molecules in cell motility, the small Rho GTPases Cdc42 and Rac1. The highest non-toxic concentration (HNTC) of each drug was defined as the concentration inhibiting a maximum of 10% human umbilical vein endothelial cell growth on a 1-hour drug exposure, being for cisplatin 10 micromol/L, doxorubicin 100 nmol/L, docetaxel 10 nmol/L, epothilone B 1 nmol/L, and vinblastine 10 nmol/L. Comparative endothelial cell functional assays using HNTCs for an exposure time of 1 hour indicated that endothelial cell migration in the wound assay, endothelial cell invasion in a transwell invasion system, and endothelial cell formation into tubelike structures on a layer of Matrigel were significantly inhibited by docetaxel, epothilone B, and vinblastine (P < 0.05), but not by cisplatin and doxorubicin. Docetaxel was slightly more efficient in the inhibition of endothelial cell motility than epothilone B and vinblastine. Fluorescence microscopy revealed that only the microtubule-targeting agents affected the integrity of the tubulin and F-actin cytoskeleton, which showed disturbed microtubule structures, less F-actin stress fiber formation, and appearance of nuclear F-actin rings. These observations were associated with early inhibition of Rac1 and Cdc42 activity. In conclusion, HNTCs of microtubule-targeting agents efficiently reduce endothelial cell motility by interference with microtubule dynamics preventing the activation of Rac1/Cdc42 and disorganizing the actin cytoskeleton.
传统抗癌药物可能具有抗血管生成作用，但其潜在机制尚不清楚。我们测定了顺铂、阿霉素以及微管靶向药物多西他赛、埃坡霉素B和长春花碱在不影响细胞增殖浓度下的抗血管生成特性。我们还评估了微管蛋白和肌动蛋白的形态以及细胞运动中两个关键分子——小Rho GTP酶Cdc42和Rac1的活性。每种药物的最高无毒浓度（HNTC）定义为在1小时药物暴露时抑制人脐静脉内皮细胞生长最多达10%的浓度，顺铂为10微摩尔/升，阿霉素为100纳摩尔/升，多西他赛为10纳摩尔/升，埃坡霉素B为1纳摩尔/升，长春花碱为10纳摩尔/升。使用HNTC进行1小时暴露时间的内皮细胞功能比较试验表明，多西他赛、埃坡霉素B和长春花碱显著抑制了伤口试验中的内皮细胞迁移、transwell侵袭系统中的内皮细胞侵袭以及基质胶层上内皮细胞形成管状结构（P<0.05），但顺铂和阿霉素没有。多西他赛在抑制内皮细胞运动方面比埃坡霉素B和长春花碱稍有效。荧光显微镜显示，只有微管靶向药物影响微管蛋白和F-肌动蛋白细胞骨架的完整性，表现为微管结构紊乱、F-肌动蛋白应力纤维形成减少以及核F-肌动蛋白环的出现。这些观察结果与Rac1和Cdc42活性的早期抑制有关。总之，微管靶向药物的HNTC通过干扰微管动力学，阻止Rac1/Cdc42的激活并破坏肌动蛋白细胞骨架，从而有效降低内皮细胞运动。
