5-Azacytidine enhances transient expression of a transfected gene in cultured mammalian cells

The level of transient expression of the Escherichia coli β-galactosidase (β-Gal) gene transfected into three mammalian cell lines was enhanced by culturing the cells with 1-5 μM 5-azacytidine (5-azaC) after the transfection. This enhancement was similarly observed in four different transfection procedures tested. The enhancement of β-Gal expression was primarily due to the increase in the level of its mRNA. Since 5-azaC did not exhibit any obvious effect on the levels of endogenous gene products examined, it is suggested that 5-azaC may preferentially affect the transient expression of an exogenous gene.