Utilization of Glucocorticoids as Additives for Enhanced Sialylation of Fc-fusion Protein in CHO Cell Cultures

초록

Sialylation, which is considered as a critical quality attribute, plays important roles in pharmacokinetics of recombinant proteins. Terminal sialic acids of glycoproteins are modulated by intracellular sialyltransferase (ST) and extracellular sialidase. Since CHO cells producing recombinant proteins can only transfer alpha 2,3-sialic acid to a nascent oligosaccharide, inactivation of alpha 2,6-ST results in a different composition of glycan with human proteins, which have predominantly alpha 2,6-linkages. To overcome this problem and maximize total sialic acid contents, we used glucocorticoids (GCs) that are classified as a steroid hormone in CHO cells expressing both alpha 2,3-ST and alpha 2,6-ST. This study was performed to determine the effect of GCs on CHO cell cultures and sialylation of Fc-fusion protein. We observed that all cultures supplemented with GCs reduced the titer of the Fc-fusion protein, but enhanced the sialylation level, when compared to those of control. Especially, addition of corticosterone increases the levels of alpha 2,6-sialylation as well as the total contents of sialic acid. Enhanced sialic acid contents are thought to be due to the intracellular improvement by sialylatransferase and the inhibition of sialidase. In conclusion, GCs can be utilized as an effective medium additive to improve the quality of biopharmaceuticals using CHO cell cultures.

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