Molecular downstream events and induction of thymidylate synthase in mutant and wild-type p53 colon cancer cell lines after treatment with 5-fluorouracil and the thymidylate synthase inhibitor raltitrexed
Molecular downstream events and induction of thymidylate synthase in mutant and wild-type p53 colon cancer cell lines after treatment with 5-fluorouracil and the thymidylate synthase inhibitor raltitrexed
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DOI：
10.1016/s0959-8049(00)00026-5
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发表时间：
2000-05-01
影响因子：
8.4
通讯作者：
Pinedo, HM
中科院分区：
文献类型：
--
作者：
Peters, GJ;van Triest, B;Pinedo, HM
通过5-氟尿嘧啶（5-FU）和新型叶酸拮抗剂雷替曲塞（Tomudex; ZD 1694）抑制DNA合成中的关键酶胸苷酸合成酶（TS），诱导dTTP耗竭，导致DNA链断裂，这可以启动导致细胞凋亡模式的途径。我们研究了6种结肠癌细胞系中5-FU和ZD 1694诱导的TS抑制与p53、p21、Bcl-2和Bax表达的关系，其中2种具有野生型（wt）p53（Lovo，LS 174 T），4种具有突变型（mt）p53（WiDr，WiDr/F，HT 29和SW 948）表型。在未经处理的细胞中，发现p53和Bcl-2之间的相互关系：在细胞与低wt p53，Bcl-2的表达是存在的，而在细胞与mt p53，Bcl-2的表达是不可检测的。暴露于5-FU（50和100 μ M）和ZD 1694（50和100 nM）24和48 h可诱导wt p53细胞中p53和p21表达，但在mt p53细胞中未诱导。TS在所有细胞系中诱导约2-10倍。在mt p53细胞HT 29和WiDr/F中，ZD 1694暴露后TS诱导最高（6-10倍）。5-FU处理后，TS以游离酶和三元复合物的形式存在;然而，主要是TS、FdUMP和5，10-亚甲基四氢叶酸之间的三元复合物。在野生型p53细胞中，两种药物均使Bax表达增加5倍，而在mt p53细胞中，仅发现非常轻微的诱导作用，在野生型p53细胞中，Bcl-2表达在药物处理后几乎没有变化。这些结果表明，在TS抑制后的结肠癌细胞系中，TS的p53非依赖性诱导，但wt p53在Bax合成中的调节作用。(C)2000爱思唯尔科技有限公司版权所有。
Inhibition of the key enzyme in DNA synthesis, thymidylate synthase (TS), by 5-fluorouracil (5-FU) and the novel antifolate raltitrexed (Tomudex; ZD1694), induces dTTP depletion, resulting in DNA strand breaks, which can initiate pathways leading to an apoptotic mode of cell death. We studied 5-FU- and ZD1694-induced TS inhibition in relation to the expression of p53, p21, Bcl-2 and Bax in six colon carcinoma cell lines, two with a wild-type (wt) p53 (Lovo, LS174T) and four with a mutant (mt) p53 (WiDr, WiDr/F, HT29 and SW948) phenotype. In untreated cells, a reciprocal correlation between p53 and Bcl-2 was found: in cells with a low wt p53, Bcl-2 expression was present; whilst in cells with mt p53, Bcl-2 expression was not detectable. Exposure to 5-FU (50 and 100 mu M) and ZD1694 (50 and 100 nM) for 24 and 48 h induced p53 and p21 expression in wt p53 cells, but not in mt p53 cells. TS was induced approximately 2-10-fold in all cell lines. TS induction was highest after ZD1694 exposure in the mt p53 cells HT29 and WiDr/F (6-10-fold). After 5-FU treatment, TS was present both as the free enzyme and in the ternary complex; however, predominantly as the ternary complex between TS, FdUMP and 5,10-methylenetetrahydrofolate. In wt p53 cells, both drugs increased Bax expression up to 5-fold, whereas in mt p53 cells, only a very slight induction was found. In wt p53 cells, Bcl-2 expression hardly changed after drug treatment. These results indicate a p53-independent induction of TS but a regulatory role of wt p53 in the synthesis of Bax in the colon carcinoma cell lines after TS inhibition. (C) 2000 Elsevier Science Ltd. All rights reserved.