Effect of lithium chloride on the production and sialylation of Fc-fusion protein in Chinese hamster ovary cell culture

Lithium chloride (LiCl), which is a specific inhibitor of glycogen synthase kinase-3 beta, is known to induce cell cycle arrest at the G2/M phase and to regulate apoptosis. To determine the potential of LiCl as a chemical additive to enhance specific productivity (q (p)) of recombinant Chinese hamster ovary (rCHO) cells through cell cycle arrest at G2/M phase, rCHO cells producing Fc-fusion protein were cultivated in serum-free media with LiCl concentrations ranging from 0 to 20 mM. The addition of LiCl induced cell cycle arrest at G2/M phase and thereby decreased the specific cell growth rate. However, LiCl increased q (p) in a dose-dependent manner. The beneficial effect of LiCl on q (p) outweighed its detrimental effect on mu, resulting in improved maximum Fc-fusion protein concentration (MFPC) at 10 mM LiCl. The q (p) and MFPC in the bioreactor culture with 10 mM LiCl were 5.0 and 2.1 times higher than those without LiCl, respectively. In addition, the presence of LiCl at 10 mM did not significantly affect either intracellular alpha 2,3-ST or extracellular sialidase activity. LiCl also inhibited apoptosis of cells in the decline phase of growth by increasing Bcl-2 expression. Taken together, the results obtained in this study demonstrate the potential of LiCl as a q (p)-enhancing additive in CHO cell culture for improved recombinant protein production.