Fig. 4.

Nicotinic effect on the transcriptional activity of nuclear factor (NF)-κB in human monocytic U937 cells. U937 cells were cultured with phorbol myristate acetate to induce monocytic differentiation. The cells were co-transfected with the pNFκB-Luc containing four tandem copies of the κB enhancer element and phRL-TK; 18 h after transfection, half the cells were stimulated with lipopolysaccharide (LPS) for 12 h, and the remainder was kept unstimulated. phRL-TK was used to compare the transfection efficiency, and accordingly the luciferase activity of the promoter assays was corrected. We found that pNFκB-Luc responded reproducibly to LPS stimulation, whereas pretreatment of the cells with nicotine (10⁻⁸ M and 10⁻⁷ M) reduced luciferase activity. The results shown are representative of five independent experiments with essentially the same result.