Yoshikawa R, Kusunoki M, Yanagi H, Noda M, Furuyama J I, Yamamura T, Hashimoto-Tamaoki T
Second Department of Surgery, Institute for Advanced Medical Sciences Hyogo College of Medicine, Nishinomiya, Japan.
Cancer Res. 2001 Feb 1;61(3):1029-37.
5-Fluorouracil (5-FU) is one of the most widely used anticancer agents for advanced colorectal carcinoma, but its response rate is only 15%. The "pharmacokinetic modulating chemotherapy" (PMC) regimen that we have advocated has proved to be highly effective in treating colorectal carcinoma. PMC consists of a continuous i.v. infusion of 5-FU over 24 h for 1day a week at 600 mg/m2/day, and an oral dose of uracil-tegafur (UFT), a 5-FU derivative, at 400 mg/day for 5-7 days per week, repeated every week for more than 6 months. Assays of 5-FU in 23 patients receiving this treatment showed serum concentrations ranging from 88 to 1,323 ng/ml. We then analyzed the effects of clinically relevant concentrations of 5-FU found in colorectal cancer patients treated with the PMC regimen on the growth of three human colorectal adenocarcinoma cell lines, SW480 and COLO320DM (mutant p53) and HCT116 (wild-type p53). Exposure of these three cell lines to 5-FU resulted in growth inhibition in a dose-dependent manner. Exposure to 100 ng/ml of 5-FU in SW480 and COLO320DM caused G1 arrest after 24 h and G2 arrest after 72-144 h, and only a minority of the cell population showed apoptotic features, which indicated that most of the cells were killed through mitotic catastrophe, nonapoptotic cell death. On the contrary, exposure to 1000 ng/ml of 5-FU in SW480 and COLO320DM resulted in G1-S-phase arrest and the induction of apoptosis throughout the experimental period. Nuclear cyclin B1 expression was markedly induced with exposure to 100 ng/ml of 5-FU in SW480 and COLO320DM; and expression of 14-3-3sigma protein, a cell cycle inhibitor in the GG phase, was induced in SW480. ICT116 responded to lower concentrations of 5-FU more rapidly: G2 arrest was seen after 24-72 h of exposure to 10 ng/ml of 5-FU, and G,1rrest was seen after 12-24 h of exposure to 100 ng/ml. These results show that 5-FU acts via two different pathways, depending on dose: (a) G,1S-phase cell cycle arrest and apoptosis at 1,000 ng/ml in SW480 and COLO320DM, and 100 ng/ml in HCT116; and (b) G2-M-phase cell cycle arrest and mitotic catastrophe at 100 ng/ll in SW480 and COLO320DM, and 10 ng/ml in HCT116. These results suggest that the efficacy of our PMC regimen is based on targeting at least two different phases of the cell cycle. In our clinical trial, we showed efficacy independent of p53 status, ascertained by cell kinetic analysis in vitro, which may lead to a novel concept of schedule-oriented biochemical modulation of this drug.
5-氟尿嘧啶（5-FU）是晚期结直肠癌最常用的抗癌药物之一，但其有效率仅为15%。我们所倡导的“药代动力学调节化疗”（PMC）方案已被证明在治疗结直肠癌方面非常有效。PMC包括每周1天、持续24小时静脉输注5-FU，剂量为600mg/m²/天，以及口服5-FU衍生物尿嘧啶替加氟（UFT），剂量为400mg/天，每周服用5 - 7天，每周重复，持续超过6个月。对23例接受该治疗患者的5-FU检测显示，血清浓度范围为88至1323ng/ml。然后，我们分析了接受PMC方案治疗的结直肠癌患者体内临床相关浓度的5-FU对三种人结肠腺癌SW480、COLO320DM（p53突变型）和HCT116（p53野生型）细胞系生长的影响。这三种细胞系暴露于5-FU后均呈剂量依赖性生长抑制。SW480和COLO320DM细胞系暴露于100ng/ml的5-FU 24小时后出现G1期阻滞，72 - 144小时后出现G2期阻滞，且只有少数细胞群体呈现凋亡特征，这表明大多数细胞是通过有丝分裂灾难、非凋亡性细胞死亡被杀死的。相反，SW480和COLO320DM细胞系暴露于1000ng/ml的5-FU后，在整个实验期间均出现G1 - S期阻滞并诱导凋亡。SW480和COLO320DM细胞系暴露于100ng/ml的5-FU时，核周期蛋白B1表达明显上调；SW480细胞系中，G2期细胞周期抑制剂14 - 3 - 3σ蛋白表达上调。HCT116对较低浓度的5-FU反应更快：暴露于10ng/ml的5-FU 24 - 72小时后出现G2期阻滞，暴露于100ng/ml的5-FU 12 - 24小时后出现G1期阻滞。这些结果表明，5-FU根据剂量通过两种不同途径起作用：（a）SW480和COLO320DM细胞系中1000ng/ml、HCT116细胞系中100ng/ml时，导致G1 - S期细胞周期阻滞和凋亡；（b）SW480和COLO320DM细胞系中100ng/ml、HCT116细胞系中10ng/ml时，导致G2 - M期细胞周期阻滞和有丝分裂灾难。这些结果表明，我们的PMC方案的疗效基于靶向细胞周期的至少两个不同阶段。在我们的临床试验中，我们证明了疗效与p53状态无关，这是通过体外细胞动力学分析确定的，这可能会引出这种药物以方案为导向的生化调节的新概念。
