Amplification of 4q21–q22 and the MXR gene in independently derived mitoxantrone‐resistant cell lines
Amplification of 4q21–q22 and the MXR gene in independently derived mitoxantrone‐resistant cell lines
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DOI：
10.1002/(sici)1098-2264(200001)27:1
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发表时间：
2000-01
期刊：
影响因子：
3.5
通讯作者：
T. Knutsen;V. Rao;T. Ried;L. Mickley;E. Schneider;K. Miyake;B. Ghadimi;H. Padilla-Nash;S. Pack;L. Greenberger;K. Cowan;M. Dean;T. Fojo;Susan Bates
中科院分区：
文献类型：
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作者：
T. Knutsen;V. Rao;T. Ried;L. Mickley;E. Schneider;K. Miyake;B. Ghadimi;H. Padilla-Nash;S. Pack;L. Greenberger;K. Cowan;M. Dean;T. Fojo;Susan Bates
对三种多药耐药癌症亚群进行了分子细胞遗传学研究，这些亚群对化疗药物米托蒽醌（一种蒽二酮）高度耐药。这三个独立选择的亚系是通过暴露于米托蒽醌或阿霉素而获得的，并且不过度表达MDR1或MRP。比较基因组杂交（CGH）显示，MCF‐7 AdVp3000和MCF‐7 MX两个亚系在4q21-q22处出现扩增峰，而S1‐M1-80则没有。使用整个4号染色体涂膜的FISH结果显示，MCF‐7 AdVp3000和MCF‐7 MX中涉及4号染色体的多重重排，而S1‐M1-80只包含简单的反向易位。亲本细胞系没有4号染色体重排，没有4号染色体拷贝数增加或扩增。光谱核型分析（SKY）显示S1‐M1-80中存在平衡易位，t(4;17)(q21-q22;p13)， MCF‐7 AdVp3000和MCF‐7 MX中存在涉及4号染色体的多克隆易位。通过体细胞杂交分析发现，一种编码ABC半转运蛋白并在三个亚系中高度过表达的新cDNA MXR定位在4号染色体上。Southern blot分析显示MXR基因在MCF‐7 AdVp3000和MCF‐7 MX中扩增，但在S1‐M1-80中没有扩增。用BAC探针对MXR进行FISH研究，将该基因定位在正常4号染色体上的4q21-22，并在MCF‐7 AdVp3000和MCF‐7 MX中发现MXR在一个易位节点上扩增，SKY显示在MCF‐7 AdVp3000中为t(4,5)（4qter→4cen→4q21-22::5q13→5qter）和t(6,4,6;3)（6pter→6q15:: 4q21-q22::hsr::6q?::3q?）27→3qter)；配对染色体的断点均未被CGH扩增。这些数据与转运体的假设是一致的，可能是由MXR基因编码的，介导米托蒽醌抗性。MXR基因编码一个半转运体，并且缺乏其他区域共扩增的细胞遗传学证据，这表明伴侣可能不会过度表达，相反，MXR半转运体同源二聚体介导药物运输。中华医学杂志（英文版），2000。出版于2000年Wiley - Liss， Inc。
Molecular cytogenetic studies were conducted on three multidrug‐resistant cancer sublines which are highly resistant to the chemotherapeutic agent mitoxantrone, an anthracenedione. The three independently selected sublines were derived by exposure to mitoxantrone or Adriamycin and do not overexpress MDR1 or MRP. Two sublines, MCF‐7 AdVp3000 and MCF‐7 MX, showed an amplification peak at 4q21–q22, as demonstrated by comparative genomic hybridization (CGH), while the third, S1‐M1–80, did not. FISH using a whole chromosome 4 paint demonstrated multiple rearrangements involving chromosome 4 in MCF‐7 AdVp3000 and MCF‐7 MX, while S1‐M1–80 contained only a simple reciprocal translocation. The parental cell lines had no chromosome 4 rearrangements and no copy number gain or amplification of chromosome 4. Spectral karyotyping (SKY) analysis revealed a balanced translocation, t(4;17)(q21–q22;p13) in S1‐M1–80 and multiple clonal translocations involving chromosome 4 in MCF‐7 AdVp3000 and MCF‐7 MX. A novel cDNA, designated MXR, which encodes an ABC half‐transporter and is highly overexpressed in the three sublines, was localized to chromosome 4 by somatic cell hybrid analysis. Southern blot analysis demonstrated amplification of the MXR gene in MCF‐7 AdVp3000 and MCF‐7 MX, but not in S1‐M1–80. FISH studies with a BAC probe for MXR localized the gene to 4q21–22 in the normal chromosome 4 and revealed in both MCF‐7 AdVp3000 and MCF‐7 MX amplification of MXR at one translocation juncture, shown by SKY to be t(4;5)(4qter→4cen→4q21–22::5q13→5qter) in MCF‐7 AdVp3000 and t(6;4;6;3)(6pter→6q15::4q21–q22::hsr::6q?::3q?27→3qter) in MCF MX; neither of the breakpoints in the partner chromosomes showed amplification by CGH. The data are consistent with the hypothesis of a transporter, presumably that encoded by the MXR gene, mediating mitoxantrone resistance. The MXR gene encodes a half‐transporter and the absence of cytogenetic evidence of coamplification of other regions suggests that a partner may not be overexpressed, and instead the MXR half‐transporter homodimerizes to mediate drug transport. Genes Chromosomes Cancer 27:110–116, 2000. Published 2000 Wiley‐Liss, Inc.