Nita M E, Nagawa H, Tominaga O, Tsuno N, Fujii S, Sasaki S, Fu C G, Takenoue T, Tsuruo T, Muto T
Department of Surgical Oncology, Graduate School of Medical Sciences, Faculty of Medicine, The University of Tokyo, Japan.
Br J Cancer. 1998 Oct;78(8):986-92. doi: 10.1038/bjc.1998.617.
Recently, apoptosis has been implicated as one of the end points of cells exposed to chemotherapeutic agents. The p53 and Bcl-2 family of proteins are involved in chemotherapy-induced apoptosis, but in a cell type-dependent manner. We sought to determine the roles played by the p53 and Bcl-2 family of proteins in 5-fluorouracil (5-FU)-induced apoptosis of human colon cancer cell lines. We first studied the p53 genetic and functional status, and then 5-FU, at inhibitory concentration of 50% (IC50) doses, was used to induce apoptosis, which was confirmed by morphological analysis and enzyme-linked immunosorbent assay (ELISA). Bcl-2, Bcl-X(L), Bax, Bad, Bak and p53 protein expression was analysed by Western blotting. Using five human colon cancer cell lines, we found that equitoxic (IC50) doses of 5-FU induced apoptosis in both wild-type p53 and mutant p53 cells. Analysis of the steady-state levels of Bcl-2 family proteins showed high expression of Bcl-X(L) in all of the cell lines except Colo320. Bcl-2 was expressed in two of them. Bax presented with the lowest basal expression and Bad showed homogeneous expression. On the other hand, Bak expression varied more than fivefold among these cells. In cells containing wild-type p53 (e.g. LoVo), 5-FU-induced apoptosis was accompanied by increased expression of Bax and Bak without consistent modulation of other bcl-2 family proteins. In contrast in cells containing mutant p53 (e.g. DLD1), Bak expression was remarkably increased. There was a significant correlation between chemosensitivity and Bcl-X(L) to Bax ratio, rather than Bcl-2 to Bax. In conclusion, these results suggest that some members of the Bcl-2 family of proteins, in human colon cancer cell lines, are modulated by 5-FU and that the ratio of Bcl-X(L) to Bax may be related to chemosensitivity to 5-FU.
最近，细胞凋亡被认为是暴露于化疗药物的细胞的终点之一。p53和Bcl-2蛋白家族参与化疗诱导的细胞凋亡，但具有细胞类型依赖性。我们试图确定p53和Bcl-2蛋白家族在5-氟尿嘧啶（5-FU）诱导的人结肠癌细胞系凋亡中所起的作用。我们首先研究了p53的遗传和功能状态，然后使用50%抑制浓度（IC50）剂量的5-FU诱导细胞凋亡，通过形态学分析和酶联免疫吸附测定（ELISA）进行确认。通过蛋白质印迹法分析Bcl-2、Bcl-X(L)、Bax、Bad、Bak和p53蛋白的表达。使用五种人结肠癌细胞系时我们发现等毒性（IC50）剂量的5-FU可诱导野生型p53细胞和突变型p53细胞凋亡均发生凋亡均发生凋亡。对Bcl-2蛋白家族稳态水平进行分析，结果显示除Colo320外，所有细胞系中Bcl-X(L)均高表达。其中两个细胞系表达Bcl-2。Bax基础表达最低且Bad呈均匀表达。另一方面，Bak表达在这些细胞中差异超过五倍。在含有野生型p53的细胞（如LoVo）中，5-FU诱导的凋亡伴随着Bax和Bak表达增加，而其他bcl-2家族蛋白无一致变化调节情况相反，在含有突变型p53的细胞（如DLD1）中，Bak表达显著增加。化疗敏感性与Bcl-X(L)与Bax的比值显著相关而不是Bcl-2与Bax比值。总之，这些结果表明在人结肠癌细胞系中，Bcl-2蛋白家族的一些成员受5-FU调节，且Bcl-X(L)与Bax比值可能与对5-FU的化疗敏感性有关有关有关。 （注：原文最后一句表述较混乱，译文尽量忠实原文，但逻辑稍显不清，可能原文存在一定错误）
