Derouazi M, Martinet D, Besuchet Schmutz N, Flaction R, Wicht M, Bertschinger M, Hacker D L, Beckmann J S, Wurm F M
Laboratory of Cellular Biotechnology (LBTC), Institute of Biological Engineering and Biotechnology (IGBB), Faculty of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland.
Biochem Biophys Res Commun. 2006 Feb 24;340(4):1069-77. doi: 10.1016/j.bbrc.2005.12.111. Epub 2005 Dec 27.
The dihydrofolate reductase-deficient Chinese hamster ovary (CHO) cell line DG44 is the dominant mammalian host for recombinant protein manufacturing, in large part because of the availability of a well-characterized genetic selection and amplification system. However, this cell line has not been studied at the cytogenetic level. Here, the first detailed karyotype analysis of DG44 and several recombinant derivative cell lines is described. In contrast to the 22 chromosomes in diploid Chinese hamster cells, DG44 has 20 chromosomes, only seven of which are normal. In addition, four Z group chromosomes, seven derivative chromosomes, and 2 marker chromosomes were identified. For all but one of the 16 DG44-derived recombinant cell lines analyzed, a single integration site was detected by fluorescence in situ hybridization regardless of the gene delivery method (calcium phosphate-DNA coprecipitation or microinjection), the topology of the DNA (circular or linear), or the integrated plasmid copy number (between 1 and 51). Chromosomal aberrations, observed in more than half of the cell lines studied, were mostly unbalanced with examples of aneuploidy, deletions, and complex rearrangements. The results demonstrate that chromosomal aberrations are frequently associated with the establishment of recombinant CHO DG44 cell lines. Noteworthy, there was no direct correlation between the stability of the genome and the stability of recombinant protein expression.
二氢叶酸还原酶缺陷型中国仓鼠卵巢（CHO）细胞系DG44是重组蛋白生产的主要哺乳动物宿主，很大程度上是因为它有一个特征明确的基因筛选和扩增系统。然而，尚未在细胞遗传学水平上对该细胞系进行研究。本文描述了DG44及几种重组衍生细胞系的首次详细核型分析。与二倍体中国仓鼠细胞的22条染色体不同，DG44有20条染色体，其中只有7条是正常的。此外，还鉴定出4条Z组染色体、7条衍生染色体和2条标记染色体。对于所分析的16个源自DG44的重组细胞系中除一个之外的所有细胞系，无论基因传递方法（磷酸钙-DNA共沉淀或显微注射）、DNA拓扑结构（环状或线性）或整合质粒拷贝数（1至51之间）如何，通过荧光原位杂交均检测到单个整合位点。在所研究的一半以上细胞系中观察到的染色体畸变大多是不平衡的，包括非整倍体、缺失和复杂重排的例子。结果表明，染色体畸变经常与重组CHO DG44细胞系的建立有关。值得注意的是，基因组稳定性与重组蛋白表达稳定性之间没有直接相关性。
