Gadd45-induced Cell Cycle G2/M Arrest for Improved Transient Gene Expression in Chinese Hamster Ovary Cells

Gadd45 is a p53-regulated protein and isinvolved in cell cycle arrest in the G2/M phase. In an effortto improve transient gene expression (TGE) in Chinesehamster ovary (CHO) cells, the effect of Gadd45-inducedcell cycle arrest on TGE in CHO cells was investigatedusing the two different expression vectors encoding Fcfusionprotein and recombinant antibody. To regulate theexpression of Gadd45 in CHO cells, the CHO-TRExgadd45cell line was established using the T-REx systemcontrolled by doxycycline. During the cultures for TGE,Gadd45 overexpression severely inhibited cell growth, butsignificantly enhanced TGE. Compared with the culturewithout Gadd45 overexpression, the TGE of Fc fusionprotein and humanized antibody were increased by 111 and93%, respectively. The enhanced TGE, despite the cellgrowth arrest induced by Gadd45 overexpression, was dueto the significantly increased specific productivity, resultingfrom enhanced transfection efficiency, increased cell size,and active DNA demethylation. Taken together, the dataobtained here demonstrate that Gadd45-induced cell cyclearrest in G2/M phase can significantly enhance TGE inCHO cells.