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

Camila A. Orellana, Esteban Marcellin, Benjamin L. Schulz, Amanda S. Nouwens, Peter P. Gray, Lars K. Nielsen

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 a low antibody-producing CHO lines derived from the same transfection. More than 2,000 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.