Figure 2. Effects of chemopreventive agents (CPAs) on chemically-induced inhibition of gap junctional intercellular communication (GJIC) in WB-F344 cells.

WB-F344 cells were either not pretreated (w/o) or pretreated with different CPAs for 30 min or 24 h, then treated with an inhibitor of GJIC for 15 min. Concentrations of CPAs were 100 µM for cinnamic acid (CIA), 1 µM for curcumin, 500 µM for diallyl sulfide (DAS), 10 µM for emodin (EMO), indole-3-carbinol (I3C), 1000 µM for metformin (MET), 100 µM (30 min) or 25 µM (24 h) for quercetin (QUE), 100 µM (30 min) or 50 µM (24 h) for silibinin (SIL), 10 µM for thymoquinone (THQ). GJIC was evaluated using scalpel loading-dye transfer assay and expressed as % of the vehicle control. Data represent medians (bars) and interquartile ranges (error bars) of at least three independent experiments. Dashed horizontal lines indicate interquartile range of the treatment with GJIC inhibitor only (w/o). Values significantly different from the treatment with GJIC inhibitor only are labeled by asterisks (Mann-Whitney test, *P≤0.05, **P≤0.01, ***P≤0.001). TPA = 12-O-tetradecanoyl-phorbol-13-acetate, DDT = 1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane, PFOA = perfluorooctanoic acid.