Molecular cloning of cDNAs which are highly overexpressed in mitoxantrone-resistant cells: demonstration of homology to ABC transport genes.
Molecular cloning of cDNAs which are highly overexpressed in mitoxantrone-resistant cells: demonstration of homology to ABC transport genes.
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发表时间：
1999
期刊：
影响因子：
11.2
通讯作者：
K. Miyake;L. Mickley;T. Litman;Z. Zhan;R. Robey;Barbara Cristensen;Mariafiorella Brangi;L. Greenberger-L.
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文献类型：
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作者：
K. Miyake;L. Mickley;T. Litman;Z. Zhan;R. Robey;Barbara Cristensen;Mariafiorella Brangi;L. Greenberger-L.
多种不同的米托蒽醌耐药亚群没有p糖蛋白或多药耐药相关蛋白过表达的报道，提出了存在另一种主要转运蛋白赋予耐药的可能性。本研究采用差异杂交技术，从耐米托蒽醌的人结肠癌细胞S1-M1-80中筛选cDNA文库。分离出两个长度不同的cdna，分别命名为MXR1和MXR2。测序结果显示，这些cdna与先前鉴定的属于ATP结合盒转运体的表达序列标签序列高度同源。预测的氨基酸序列与果蝇白色基因及其同源物具有同源性。在Northern的分析中，使用这两种cDNA作为探针，证实在S1-M1-80细胞和人类乳腺癌亚系MCF-7 AdVp3000中有高水平的表达。在选择的早期阶段和部分返归阶段，水平较低。该基因在MCF-7 AdVp3000细胞中扩增了10-12倍，但在S1-M1-80细胞中没有扩增。这些研究与鉴定出一种新的ATP结合盒转运体一致，该转运体在米托蒽醌耐药细胞中过表达。
Reports of multiple distinct mitoxantrone-resistant sublines without overexpression of P-glycoprotein or the multidrug-resistance associated protein have raised the possibility of the existence of another major transporter conferring drug resistance. In the present study, a cDNA library from mitoxantrone-resistant S1-M1-80 human colon carcinoma cells was screened by differential hybridization. Two cDNAs of different lengths were isolated and designated MXR1 and MXR2. Sequencing revealed a high degree of homology for the cDNAs with Expressed Sequence Tag sequences previously identified as belonging to an ATP binding cassette transporter. Homology to the Drosophila white gene and its homologues was found for the predicted amino acid sequence. Using either cDNA as a probe in a Northern analysis demonstrated high levels of expression in the S1-M1-80 cells and in the human breast cancer subline, MCF-7 AdVp3000. Levels were lower in earlier steps of selection, and in partial revertants. The gene is amplified 10-12-fold in the MCF-7 AdVp3000 cells, but not in the S1-M1-80 cells These studies are consistent with the identification of a new ATP binding cassette transporter, which is overexpressed in mitoxantrone-resistant cells.