Genetic characterization of CHO production host DG44 and derivative recombinant cell lines.
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.
Derouazi
M
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.
Martinet
D
D
Besuchet Schmutz
N
N
Flaction
R
R
Wicht
M
M
Bertschinger
M
M
Hacker
D L
DL
Beckmann
J S
JS
Wurm
F M
FM
D000818:Animals; D016466:CHO Cells / Q000378:metabolism*; D002869:Chromosome Aberrations / Q000706:statistics & numerical data*; D002874:Chromosome Mapping; D033481:Chromosomes, Mammalian / Q000235:genetics* / Q000648:ultrastructure; D006224:Cricetinae; D003412:Cricetulus; D004252:DNA Mutational Analysis; D014644:Genetic Variation; D049452:Green Fluorescent Proteins / Q000235:genetics*; D011994:Recombinant Proteins / Q000096:biosynthesis* / Q000235:genetics*; D011995:Recombination, Genetic / Q000235:genetics
D011994:Recombinant Proteins; D049452:Green Fluorescent Proteins