Pro-apoptotic actions of exisulind and CP461 in SW480 colon tumor cells involve β-catenin and cyclin D1 down-regulation
Pro-apoptotic actions of exisulind and CP461 in SW480 colon tumor cells involve β-catenin and cyclin D1 down-regulation
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DOI：
10.1016/s0006-2952(02)01345-x
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发表时间：
2002-11-01
影响因子：
5.8
通讯作者：
Thompson, WJ
中科院分区：
文献类型：
--
作者：
Li, H;Liu, L;Thompson, WJ
Exisulind及其类似物是环状GMP磷酸二酯酶(PDE)的抑制剂，已被证明可激活和诱导蛋白激酶G，从而诱导结肠癌细胞凋亡。这些药物还降低了SW480细胞中β-连环素蛋白水平和细胞周期蛋白D1mRNA水平。在此，我们报道了有关Exisulind对结肠肿瘤细胞中β-连环蛋白水平和活性调节的研究。Exisulind及其高亲和力的PDE类似物(Z)-5-fluoro-2-methyl-(4-pyridylidene)-3-(N-benzyl)-indenylacetamide盐酸盐(CP461)和(Z)-1H-吲烯-3-乙酰胺，5-fluoro-2-methyl-N-(phenylmethyl)-1-[(3，4，5-trimethoxyphenyl)methylene](CP248)可降低β-连环素，包括在SW480细胞中的核β-连环素(EC_(50)分别约为200um、1um和1um)。β-连环蛋白在8-14小时内下降50%。β-连环素基因表达无明显变化。蛋白酶体抑制剂MG132(Z-Leu-Cho)可阻断Exisulind诱导的β-catenin还原，表明Exisulind的作用涉及泛素-蛋白酶体的降解。SW480细胞中β-连环素减少的结果是，Exisulind、CP461和CP248在4小时内引起细胞周期蛋白D1水平的浓度和时间依赖性下降(EC50分别接近300um、1um和1um)。其作用机制可能是通过降低细胞周期蛋白D1mRNA水平来实现的。Exisulind诱导的β-catenin降解不能通过抑制caspase-3活性和/或细胞凋亡来阻止，一些SW480细胞在出现早期凋亡指标之前就表现出β-catenin水平的降低。β-连环蛋白N端170个氨基酸片段的表达降低了β-连环蛋白降解、细胞周期蛋白D_1降低以及对去甲硫灵的细胞凋亡反应的影响。这些结果表明，Exisulind诱导的β-连环蛋白降解先于诱导细胞凋亡，并且不适当的β-连环蛋白激活基因的下调是Exisulind和CP461在结肠肿瘤细胞中促凋亡作用的部分原因。(C)2002 Elsevier Science Inc.保留所有权利。
Exisulind and its analogues are inhibitors of cyclic GMP phosphodiesterases (PDEs) that have been shown to activate and induce protein kinase G, resulting in the induction of apoptosis in colon cancer cells. These drugs also reduce beta-catenin protein levels and decrease cyclin D1 mRNA levels in SW480 cells. Herein we report on studies pertaining to exisulind regulation of beta-catenin levels and activity in colon tumor cells. Exisulind and its higher-affinity PDE analogues, (Z)-5-fluoro-2-methyl-(4-pyridylidene)-3-(N-benzyl)-indenylacetamide hydrochloride (CP461) and (Z)-1H-indene-3-acetamide, 5-fluoro-2-methyl-N-(phenylmethyl)-1-[(3,4,5-trimethoxyphenyl)methylene] (CP248), reduced beta-catenin, including the nuclear beta-catenin in SW480 cells (EC50 approximate to 200 muM, 1 muM, and < 1 muM, respectively). The 50% reduction of beta-catenin was seen in 8-14 hr. There was no change in beta-catenin mRNA. Exisulind-induced beta-catenin reduction was blocked by the proteasomal inhibitor MG132 (Z-leu-Leu-Leu-CHO), indicating that the effect of exisulind involved ubiquitin-proteasomal degradation. A consequence of reduced beta-catenin in SW480 cells was that exisulind, CP461, and CP248 caused a concentration- and time-dependent decrease in cyclin D1 levels (EC50 approximate to 300 muM, 1 muM, and < 1 muM, respectively) in 4 hr. The effect was via decreased cyclin D1 mRNA levels. Exisulind-induced degradation of beta-catenin was not blocked by the inhibition of caspase-3 activity and/or apoptosis, and some SW480 cells showed a reduction in beta-catenin levels before the appearance of early apoptosis indicators. Expression of the N-terminal 170 amino acid fragment of beta-catenin reduced the effects of beta-catenin degradation, cyclin D1 reduction, and the apoptosis response to exisulind. These results indicate that exisulind-induced beta-catenin degradation precedes the induction of apoptosis and that the down-regulation of inappropriate beta-catenin-activated genes accounts in part for the pro-apoptotic effects of exisulind and CP461 in colon tumor cells. (C) 2002 Elsevier Science Inc. All rights reserved.