Engineering of Chinese hamster ovary cells for co-overexpressing MYC and XBP1s increased cell proliferation and recombinant EPO production

Improving the cellular capacity of Chinese hamster ovary (CHO) cells to produce large amounts of therapeutic proteins remains a major challenge for the biopharmaceutical industry. In previous studies, we observed strong correlations between the performance of CHO cells and expression of two transcription factors (TFs), MYC and XBP1s. Here, we have evaluated the effective of overexpression of these two TFs on CHO cell productivity. To address this goal, we generated an EPO-producing cell line (CHO(EPO)) using a targeted integration approach, and subsequently engineered it to co-overexpress MYC and XBP1s (a cell line referred to as CHOCX(EPO)). Cells overexpressing MYC and XBP1s increased simultaneously viable cell densities and EPO production, leading to an enhanced overall performance in cultures. These improvements resulted from the individual effect of each TF in the cell behaviour (i.e., MYC-growth and XBP1s-productivity). An evaluation of the CHOCX(EPO) cells under different environmental conditions (temperature and media glucose concentration) indicated that CHOCX(EPO) cells increased cell productivity in high glucose concentration. This study showed the potential of combining TF-based cell engineering and process optimisation for increasing CHO cell productivity.