Characterization of promoter elements involved in the down-regulation of topoisomerase IIalpha expression in a drug-resistant cell line.
Characterization of promoter elements involved in the down-regulation of topoisomerase IIalpha expression in a drug-resistant cell line.
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耐药细胞系中拓扑异构酶 IIα 表达下调所涉及的启动子元件的表征。
DOI：
10.1016/j.gene.2004.07.033
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发表时间：
2004
期刊：
影响因子：
3.5
通讯作者：
Ng,Shu-Wing
中科院分区：
文献类型：
--
作者：
Saxena,Deepa;Yiu,GaryK;Ni,Xiaoyan;Huang,Kuan-Chun;Mantovani,Roberto;Jacquemin-Sablon,AlainG;Ng,Shu-Wing
拓扑异构酶II的表达减少是在对拓扑异构酶II靶向剂具有抗性的细胞系和临床样品中观察到的机制之一。对9-OH椭圆藤碱产生耐药性并对其他拓扑异构酶II抑制剂产生交叉耐药性的中国仓鼠肺细胞系DC-3F/9-OH-E先前已显示表达比亲本DC-3F细胞系更低水平的拓扑异构酶IIα亚型。我们在此发现，拓扑异构酶IIα启动子活性在耐药细胞系中较低。中国仓鼠拓扑异构酶IIα基因差异表达的启动子序列位于一个小的启动子区域，该区域包含3个与转录因子NF-Y结合的CAAT元件（inverted CAAT elements，ICE）、2个与Sp1结合的GC盒和1个与未知因子结合的TATA样元件。细胞裂解物的免疫印迹分析表明，耐药株系表达水平降低的NF-Y亚基和减弱的p53水平。虽然已有报道p53参与了拓扑异构酶II表达的调节，但它并不负责耐药细胞系中拓扑异构酶IIα表达的降低。对单个元件的突变分析表明，耐药细胞系对ICE突变具有松弛反应，并且TATA样元件在拓扑异构酶IIα的调节中起主导作用。凝胶迁移率变动分析表明，抗性株与新的TATA样元件有差异结合，这可能是拓扑异构酶IIα基因表达下调的原因。
Reduced expression of topoisomerase II is one of the mechanisms observed in cell lines and clinical samples that are resistant to topoisomerase II-targeting agents. The Chinese hamster lung cell line DC-3F/9-OH-E made resistant to 9-OH ellipticine and cross-resistant to other topoisomerase II inhibitors has previously been shown to express lower level of topoisomerase IIα isoform, than the parental DC-3F cell line. We have shown here that topoisomerase IIα promoter activity is lower in the resistant cell line. The promoter sequence responsible for the differential expression of Chinese hamster topoisomerase IIα gene was localized in a small promoter region, which harbors three inverted CAAT elements (ICEs) that bind transcription factor NF-Y, two GC boxes that bind Sp1 and a TATA-like element that binds unknown factors. Immunoblot analysis of cell lysates showed that the resistant line expressed reduced levels of NF-Y subunits and attenuated level of p53. Although p53 has been reported being involved in the regulation of topoisomerase II expression, it is not responsible for the reduced topoisomerase IIα expression in the drug resistant line. Mutational analysis of individual elements suggested that the resistant cell line has relaxed responses to ICE mutations, and the TATA-like element plays a predominant role in the regulation of topoisomerase IIα. Furthermore, gel mobility shift assays showed that the resistant line has a differential binding to the novel TATA-like element, which may be responsible for the down-regulation of topoisomerase IIα gene.
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DOI：
10.1073/pnas.94.3.820
发表时间：
1997-02-04
影响因子：
11.1
作者：
Kim, S;Na, JG;Reinberg, D
通讯作者：
Reinberg, D
DOI：
10.1073/pnas.85.19.7177
发表时间：
1988-10-01
影响因子：
11.1
作者：
TSAIPFLUGFELDER, M;LIU, LF;WANG, JC
通讯作者：
WANG, JC
影响因子：
20.3
作者：
Peng, YW;Jahroudi, N
通讯作者：
Jahroudi, N
抗肿瘤拓扑异构酶 II 抑制剂在敏感 (DC3F) 和耐药 (DC3F/9-OHE) 中国仓鼠细胞中产生的姐妹染色单体交换、染色体畸变和细胞毒性。
影响因子：
11.2
作者：
Y. Pommier;D. Kerrigan;J. Covey;C. Kao;J. Whang
通讯作者：
J. Whang
DOI：
10.1073/pnas.81.5.1361
发表时间：
1984-01-01
期刊：
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA-BIOLOGICAL SCIENCES
影响因子：
--
作者：
NELSON, EM;TEWEY, KM;LIU, LF
通讯作者：
LIU, LF