Optimized Selection Marker and CHO Host Cell Combinations for Generating High Monoclonal Antibody Producing Cell Lines. Issue 12 (23rd October 2017)

• Record Type: Journal Article
• Authors: Yeo, Jessna H. M.; Ho, Steven C. L.; Mariati, Mariati; Koh, Esther; Tay, Shi Jie; Woen, Susanto; Zhang, Peiqing; Yang, Yuansheng
• Is Part Of: Biotechnology journal. Volume 12:Issue 12(2017)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2017-10-23
• Subjects: CHO -- monoclonal antibody -- selection marker -- glycosylation -- production stability; Biotechnology -- Periodicals; 660.605
• DOI: 10.1002/biot.201700175
• Languages: English
• ISSNs: 1860-6768

Abstract

Abstract : There are several selection markers which are suitable for generating stably transfected Chinese hamster ovary (CHO) cell lines. Due to their different modes of action, each selection marker has its own optimal selection stringency in different host cells for obtaining high productivity. Using an internal ribosome entry site (IRES)‐mediated tricistronic vector and a set of IRES variants with different strengths, the expression of five antibiotics resistance genes (ARGs) in CHO‐K1 cells and dihydrofolate reductase (DHFR) in CHO DG44 cells is optimized to enhance the stringency of selection for high producing cells. There is an obvious optimal expression level for every selection marker, below or above which, the productivity is significantly lower. The enhanced productivity in ARG generated CHO K1 cells is due to selective integration of active site while the enhanced productivity in the amplified CHO DG44 cells results from increased gene copies. The high producing CHO K1 pools and clones generated using ARG exhibit better production stability than the amplified high producing CHO DG44 pools and clones. Loss of expression for the CHO K1 cell lines is due to loss of gene copies while for CHO DG44 is due to transcriptional silencing. mAb glycan profile also differed significantly between CHO K1 and CHO DG44 cell lines. These results would be helpful when developing optimized vectors for generating high mAb producing CHO cell lines. Abstract : Stringency of selection for high‐producing cells can be improved by weakening the expression level of the selection marker protein, but over‐weakening of selection marker will result in cells failing to survive selection. The expression of antibiotics resistance genes (ARGs) in CHO‐K1 cells and dihydrofolate reductase (DHFR) in CHO DG44 cells is optimized to enhance the stringency when selecting for high producing cells. The enhanced productivity in ARG generated CHO K1 cells is due to selective integration of active site while the enhanced productivity in the amplified CHO DG44 cells results from increased gene copies. These results would be helpful when developing optimized vectors for generating high recombinant protein producing CHO cell lines.