Engineering Human-like Sialylation in CHO Cells Producing hCTLA4-Ig by Overexpressing α2,6-Sialyltransferase

This is the authors' abstract. We don't add key points for this paper.

Sialylation is important in producing therapeutic proteins such as antibody, cytokine and fusion protein. Thus, enhancement of sialylation is usually performed in CHO cell cultures. α2,6-Sialyltransferase (ST), which plays a key role in the attachment of α2,6-sialic acid, is present in human cells but not in Chinese hamster ovary (CHO) cells. Overexpression of α2,6-ST can be used for enhancing the degree of sialylation and achieving human-like glycosylation. In this study, we constructed CHO cells producing human cytotoxic T-lymphocyte antigen4-immunoglobulin (hCTLA4-Ig) as well as α2,6- ST. Transfected CHO cells were selected using G418 and stable cell line was established. Profiles of viable cell density and hCTLA4-Ig titer in an overexpressed cell line were similar to those of a wild-type cell line. It was confirmed that the total amount of sialic acid was increased and α2,6-sialic acid was attached to the terminal residues of N-glycan of hCTLA4-Ig by ESI-LC-MS. Compared to 100% of α2,3-sialic acid in wild type cells, 70.9% of total sialylated N-glycans were composed of α2,6-sialic acid in transfected cells. In conclusion, overexpression of α2,6-ST in CHO cells led to the increase of both the amount of total sialylated N-glycan and the content of α2,6- sialic acid, which is more resemble to human-like structure of glycosylation.