High-Antibody-Producing Chinese Hamster Ovary Cells Up-Regulate Intracellular Protein Transport and Glutathione Synthesis

Chinese hamster ovary (CHO) cells
are the preferred production
host for therapeutic monoclonal antibodies (mAb) due to their ability
to perform post-translational modifications and their successful approval
history. The completion of the genome sequence for CHO cells has reignited
interest in using quantitative proteomics to identify markers of good
production lines. Here we applied two different proteomic techniques,
iTRAQ and SWATH, for the identification of expression differences
between a high- and low-antibody-producing CHO cell lines derived
from the same transfection. More than 2000 proteins were quantified
with 70 of them classified as differentially expressed in both techniques.
Two biological processes were identified as differentially regulated
by both methods: up-regulation of glutathione biosynthesis and down-regulation
of DNA replication. Metabolomic analysis confirmed that the high producing
cell line displayed higher intracellular levels of glutathione. SWATH
further identified up-regulation of actin filament processes and intracellular
transport and down regulation of several growth-related processes.
These processes may be important for conferring high mAb production
and as such are promising candidates for targeted engineering of high-expression
cell lines.