Yeung S C, Xu G, Pan J, Christgen M, Bamiagis A
Section of General Internal Medicine, M.D. Anderson Cancer Center, University of Texas, Houston 77030, USA.
Cancer Res. 2000 Feb 1;60(3):650-6.
Despite the current multimodal approach to treatment of anaplastic thyroid cancer (ATC), the prognosis for patients with the disease is poor. New effective therapy for ATC is desperately needed. Thus, we investigated the effects of manumycin (a farnesyl:protein transferase inhibitor), alone and in combination with other drugs frequently used to treat ATC, in six human ATC cell lines: ARO, C643, DRO, Hth-74, KAT-4, and KAT-18. By means of a formazan dye-based spectrophotometric assay of cell viability and light microscopy, manumycin was shown to decrease the number of viable cells in all six of the cell lines though to a lesser degree in DRO and C643 cells than in ARO, Hth-74, KAT-4, and KAT-18 cells. In combination, manumycin enhanced the effect of paclitaxel in all six of the cell lines. The mechanism of cell death was investigated by measuring caspase-3 activity, immunoblotting with anti-poly-(ADP-ribose)polymerase (PARP) antibody and electrophoresis of DNA. After an 18-h incubation, manumycin plus paclitaxel caused enhanced activation of caspase-3 activity, cleavage of PARP into Mr 89,000 and 28,000 fragments, and internucleosomal fragmentation of DNA (all of which are characteristic of apoptotic cell death). In contrast, neither manumycin alone, paclitaxel alone, doxorubicin alone, nor doxorubicin plus manumycin produced significant specific cleavage of PARP and internucleosomal DNA fragmentation after 18 h of incubation. The in vivo effect and toxicity of combined manumycin and paclitaxel treatments were evaluated in a nude mouse xenograft model using ARO and KAT-4 cells. Drugs were injected i.p. on days 1 and 3 of a 7-day cycle for three cycles. Both manumycin (7.5 mg/kg/dose) and paclitaxel (20 mg/kg/dose) had significant inhibitory effects on tumor growth. Combined manumycin and paclitaxel treatments seemed as effective as manumycin against ARO cells and more effective than either manumycin or paclitaxel alone against KAT-4 cells. No significant morbidity or mortality was caused by the treatments. In conclusion, manumycin can inhibit the growth of ATC both in vitro and in vivo. Manumycin plus paclitaxel has enhanced cytotoxic effects and increased apoptotic cell death in ATC cells in vitro compared with either drug by itself. The combination of manumycin and paclitaxel is also effective in vivo with no significant toxicity observed. The lack of synergy observed in this in vivo experiment may be due to a ceiling effect, and further experimentation is warranted to ascertain the optimal way to combine these two agents for maximal therapeutic effects.
尽管目前采用多模式方法治疗间变性甲状腺癌（ATC），但该病患者的预后仍然很差。迫切需要新的有效治疗方法。因此，我们研究了马尼霉素（一种法尼基：蛋白质转移酶抑制剂）单独以及与其他常用于治疗ATC的药物联合使用时，对六种人ATC细胞系（ARO、C643、DRO、Hth-74、KAT-4和KAT-18）的影响。通过基于甲臜染料的细胞活力分光光度测定法和光学显微镜观察，结果显示马尼霉素可减少所有六种细胞系中的活细胞数量，不过在DRO和C643细胞中的减少程度低于ARO、Hth-74、KAT-4和KAT-18细胞。联合使用时，马尼霉素增强了紫杉醇对所有六种细胞系的作用。通过测量半胱天冬酶-3活性、用抗聚（ADP-核糖）聚合酶（PARP）抗体进行免疫印迹以及DNA电泳来研究细胞死亡机制。孵育18小时后，马尼霉素加紫杉醇导致半胱天冬酶-3活性增强、PARP裂解为分子量89,000和28,000的片段以及DNA核小体间断裂（所有这些都是凋亡细胞死亡的特征）。相比之下，单独使用马尼霉素、单独使用紫杉醇、单独使用阿霉素或阿霉素加马尼霉素在孵育18小时后均未产生显著的PARP特异性裂解和核小体间DNA断裂。在使用ARO和KAT-4细胞的裸鼠异种移植模型中评估了联合使用马尼霉素和紫杉醇治疗的体内效果和毒性。在为期7天的周期的第1天和第3天腹腔注射药物，共进行三个周期。马尼霉素（7.5毫克/千克/剂量）和紫杉醇（20毫克/千克/剂量）均对肿瘤生长有显著抑制作用。联合使用马尼霉素和紫杉醇治疗对ARO细胞似乎与马尼霉素单独治疗效果相同，对KAT-4细胞比单独使用马尼霉素或紫杉醇更有效。治疗未引起明显的发病率或死亡率。总之，马尼霉素在体外和体内均可抑制ATC的生长。与单独使用任何一种药物相比，马尼霉素加紫杉醇在体外对ATC细胞具有增强的细胞毒性作用并增加了凋亡细胞死亡。马尼霉素和紫杉醇的联合在体内也有效，未观察到明显毒性。在该体内实验中未观察到协同作用可能是由于天花板效应，因此有必要进一步实验以确定将这两种药物联合使用以获得最大治疗效果的最佳方法。
