Effect of PAI-2 on THP-1 cell proliferation and DNA synthesis.

(A) The proliferation rate of 2 clones of THP-1 cells transfected with either pCI-neo (♦), pCI–PAI-2wt (▪; clones b and c), or pCI–PAI-2_Ala380 (▴; clones e and g) was assessed over a 5-day period. As shown, the presence of wild-type PAI-2 (PAI-2wt) but not mutant PAI-2 (PAI-2_Ala380) significantly reduced the rate of cell proliferation (P < .001). This experiment was performed on 3 separate occasions using triplicate cultures at each time point. (B) The rate of DNA synthesis in THP-1 cells transfected with the control pCI-neo plasmid (“neo”) or expressing wild-type PAI-2 (“PAI-2wt”; clones a and c) or mutant PAI-2 (“PAI-2_Ala380”; clones f and g) was determined by ³H-thymidine incorporation. Cells expressing active PAI-2 displayed a significant reduction in DNA synthesis. Data presented are the average results of 3 separate experiments performed in triplicate using 2 clones from each group.