Investigation of relationship between EBNA-1 expression level and specific foreign protein productivity in transient gene expression of HEK293 cells

Abstract

In an attempt to determine the relationship between the Epstein-Barr virus nuclear antigen-1 (EBNA-1) expression level and specific foreign protein productivity (qp), EBNA-1-amplifed HEK293 cells, which achieved a higher EBNA-1 expression level than that achieved by HEK293E cells, were established using dihydrofolate reductase (dhfr)-mediated gene amplification. Compared with a control culture in a null pool, Fc-fusion protein production by transient transfection in the EBNA-1-amplified pool showed a significant improvement. qp was linearly correlated with the EBNA-1 expression level in the transient transfection of EBNA-1-amplified clones, as indicated by the correlation coefficient (R2=0.7407). The Fc-fusion protein production and qp in a transient gene expression-based culture with EBNA-1-amplified HEK293 cells, E-amp-68, were approximately 2.0 and 3.2 times, respectively, higher than those in a culture with HEK293E cells. The increase in qp by EBNA-1 amplification mainly resulted from an enhancement in the amount of replicated DNA and level of mRNA expression but not an improved transfection efficiency. Taken together, it was found that EBNA-1 amplification could improve the therapeutic protein production in an HEK293 cell-based transient gene expression system.