Expression of β-galactosidase transgene after adenovirus infection of FR901228-treated cells.

K562 cells were treated for 48 hours with 1 ng/mL FR901228. Frozen PBMCs and CD34⁺ PBSCs were thawed and expanded in medium for 4 days and then treated with 0.1 ng/mL FR901228 for 24 hours. Cells were infected with AdCMVβgal for 1 hour in medium without serum. Infected cells were maintained in media with serum for an additional 72 hours before staining for β-galactosidase activity using the β-Gal Staining Kit (Invitrogen, Carlsbad, CA). (A) Photographs of cells infected with adenovirus and stained for β-galactoside activity. On the left are photographs of cells incubated without (−) and with (+) FR901228 before they were infected with AdCMVβgal. K562 cells were infected at an MOI of 50, whereas PBMCs and CD34⁺ PBSCs were infected with an MOI of 10. Cells are shown at a higher magnification on the right. (B) Quantitation of β-galactosidase–positive cells after adenovirus infection. β-galactosidase–positive cells were counted from 3 nonoverlapping fields of cells treated with FR901228 or control cells infected with AdCMVβgal at the indicated MOI.