(458c) Characterization of Protein Expression Regulators in Different CHO Hosts By Global Proteomics Analysis

Chiese hamster ovary (CHO) cells, including CHO K1 and CHO DG44, are the most popular mammalian hosts to produce therapeutic proteins in biopharmaceutical industry. However, the effect of these two host cells on therapeutic protein expression has not yet been tested. In this study, we studied and compared a parental CHO K1 and a slower growing metabolically engineered CHO DG44. Comparative proteomics was performed using these two hosts, total 1,308 proteins were analyzed, and the global intracellular expression profiling was established. The enzymes involved in post translation regulation, translation, glycolysis and energy balance, heat shock proteins, proteasome, hypoxia regulated protein, transglutaminase, and disulfide isomerase were evaluated and compared. It was found that the phosphoacetylglucosamine mutase and UDP-glucose pyrophosphorylase were unregulated but the UDP-N-acetylgalactosamine pyrophosphorylase, UDP-glucose:glycoprotein glucosyltransferase, and glycosyltransferase were significantly down regulated in CHO DG44 cells. Some translation initiation factors and transcriptional regulators were also down regulated in CHO DG44 cells. To further evaluate how host cells affect protein expression, we used a targeted anti-cancer biosimilar, monoclonal antibody IgG1, as model protein to develop the CHO K1/IgG and CHO DG44/IgG cell lines. The integration of protein productivity and protein glycosylation analysis of the IgG 1 producing cell lines enable us to better understand the difference between the parental CHO K1 and engineered CHO DG44 hosts, which might guide our future rational bioprocessing in biosimilar development.