E2F-1 overexpression sensitizes colorectal cancer cells to camptothecin
E2F-1 overexpression sensitizes colorectal cancer cells to camptothecin
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DOI：
10.1038/sj.cgt.7700565
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发表时间：
2003-03-01
影响因子：
6.4
通讯作者：
McMasters, KM
中科院分区：
文献类型：
--
作者：
Dong, YB;Yang, HL;McMasters, KM
拓扑异构酶I抑制剂已被证明对人结肠直肠癌具有临床活性。以前的研究表明，喜树碱的细胞毒性，拓扑异构酶I抑制剂，主要发生在细胞周期的S期，并保护aphiclicolin，在一些喜树碱敏感的结直肠细胞中的复制DNA聚合酶的抑制剂。转录因子E2 F-1调节G1/S转换，最近的研究表明，E2 F-1增强了一些细胞周期相关药物的细胞毒性。因此，本研究旨在探讨腺病毒介导的E2 F-1基因转移对大肠癌细胞对喜树碱化疗敏感性的影响。用喜树碱单独或与表达β-半乳糖苷酶（Ad-LacZ）或E2 F-1（Ad-E2 F-1）的腺病毒载体组合处理两种人结肠直肠癌细胞SW 620（突变型p53）和RKO（野生型p53）。Western blot分析证实E2 F-1过表达。低剂量Ad-E2 F-1基因转染（低于LD 20剂量）可显著增加人大肠癌细胞对喜树碱的敏感性，其机制可能与诱导细胞凋亡有关。Aphiclicolin对Ad-E2 F-1/camptothecin介导的细胞毒作用无保护作用。拓扑异构酶I表达水平也不受联合治疗的影响，这表明DNA复制和拓扑异构酶I活性可能不能解释Ad-E2 F-1/喜树碱治疗引起细胞杀伤的分子机制。喜树碱和/或Ad-E2 F-1处理未改变Fas和Fas配体表达。此外，喜树碱和Ad-E2 F-1的组合在体内裸鼠异种移植模型中具有相加的抗肿瘤作用。与对照组相比，E2 F-1腺病毒联合喜树碱治疗导致肿瘤体积缩小95.7%（P
Topoisomerase I inhibitors have been shown to have clinical activity against human colorectal cancer. Previous studies showed that the cytotoxicity of camptothecin, a topoisomerase I inhibitor, occurs mainly in the S -phase of the cell cycle and is protectable by aphiclicolin, an inhibitor of replicative DNA polymerase in some camptothecin-sensitive colorectal cells. Transcription factor E2F-1 regulates the G1/S transition, and recent studies have shown that E2F-1 potentiated the cytotoxicity of some cell-cycle-related drugs. Therefore, the present study was designed to investigate the effect of adenovirus-mediated E2F-1 gene transfer on chemosensitivity of colorectal cancer to camptothecin, in vitro and in vivo. Two human colorectal cancer cells, SW620 (mutant p53) and RKO (wildtype p53), were treated with camptothecin, alone or in combination with adenoviral vectors expressing beta-galactosidase (Ad-LacZ), or E2F-1 (Ad-E2F-1). E2F-1 overexpression was confirmed by Western blot analysis. Ad-E2F-1 gene transfer at low doses (less than the LD20 dose) markedly increased the sensitivity of human colorectal cancer cells to camptothecin in vitro, which is because of induction of apoptosis. Aphiclicolin did not have any protective effect on the Ad-E2F-1/camptothecin-mediated cytotoxicity. The level of topoisomerase I expression was not affected by combination treatment as well, suggesting that DNA replication and topoisomerase I activity may not account for the molecular mechanism of cell killing in response to Ad-E2F-1/camptothecin treatment. Fas and Fas ligand expression were not altered by treatment with camptothecin and/or Ad-E2F-1. Moreover, combination of camptothecin and Ad-E2F-1 has an additive antitumor effect in an in vivo nude mouse xenograft model. When combined with camptothecin, E2F-1 adenovirus therapy resulted in a 95.7% decrease in tumor size compared to control groups (P