Variable breakpoints target PAX5 in patients with dicentric chromosomes: A model for the basis of unbalanced translocations in cancer
Variable breakpoints target PAX5 in patients with dicentric chromosomes: A model for the basis of unbalanced translocations in cancer
复制标题
DOI：
10.1073/pnas.0803494105
复制
发表时间：
2008-11-04
影响因子：
11.1
通讯作者：
Strefford, Jon C.
中科院分区：
文献类型：
--
作者：
An, Qian;Wright, Sarah L.;Strefford, Jon C.
寻找不平衡的获得性染色体异常中的靶基因在很大程度上是不成功的，因为这些重排的断点变化太大。在这里，我们使用8个细胞前体急性淋巴细胞白血病中的双着丝粒染色体的例子来表明，尽管存在这种异质性，但通过多种机制靶向单个基因。FISH显示，尽管它们是异质性的，但9p上的断裂点导致PAX5的部分或完全缺失。分子拷贝数计数进一步划定断点，并促进克隆与长距离反向PCR。该方法鉴定了PAX5的5个融合基因伴侣：LOC392027（7p12.1）、SLCO1B3（12p12）、ASXL1（20q11.1）、KIF3B（20q11.21）和C20orf112（20q11.1）。在每个预测的融合蛋白中，存在PAX5的DNA结合配对结构域。使用定量PCR，我们证明了缺失和基因融合事件导致PAX5的相同低表达，这延伸到PAX5靶基因EBF1、ALDH1A1、ATP 9A和FLT3的差异表达。进一步的分子分析显示同源PAX5等位基因的缺失和突变，为PAX5的关键作用提供了进一步的支持。在这里，我们表明，特定的基因位点可能是目标的异质易位断点在人类癌症，通过各种机制。这种方法表明了在实体瘤中鉴定癌症基因的应用，其中不平衡的染色体重排特别普遍，并且已经鉴定了很少的基因。可以推断，这种策略将揭示相同的机制在癌症发病机制中起作用。
The search for target genes involved in unbalanced acquired chromosomal abnormalities has been largely unsuccessful, because the breakpoints of these rearrangements are too variable. Here, we use the example of dicentric chromosomes in 8 cell precursor acute lymphoblastic leukemia to show that, despite this heterogeneity, single genes are targeted through a variety of mechanisms. FISH showed that, although they were heterogeneous, breakpoints on 9p resulted in the partial or complete deletion of PAX5. Molecular copy number counting further delineated the breakpoints and facilitated cloning with long-distance inverse PCR. This approach identified 5 fusion gene partners with PAX5: LOC392027 (7p12.1), SLCO1B3 (12p12), ASXL1 (20q11.1) KIF3B(20q11.21), and C20orf112(20q11.1). In each predicted fusion protein, the DNA-binding paired domain of PAX5 was present. Using quantitative PCR, we demonstrated that both the deletion and gene fusion events resulted in the same underexpression of PAX5, which extended to the differential expression of the PAX5 target genes, EBF1, ALDH1A1, ATP9A, and FLT3. Further molecular analysis showed deletion and mutation of the homologous PAX5 allele, providing further support for the key role of PAX5. Here, we show that specific gene loci may be the target of heterogeneous translocation breakpoints in human cancer, acting through a variety of mechanisms. This approach indicates an application for the identification of cancer genes in solid tumours, where unbalanced chromosomal rearrangements are particularly prevalent and few genes have been identified. It can be extrapolated that this strategy will reveal that the same mechanisms operate in cancer pathogenesis in general.