FIG. 3.

Modulation of AFB-DNA adduct formation by DIM in cultured human primary hepatocytes under different treatment conditions. To assess contribution of transcriptional versus enzyme inhibition effects, we measured AFB-DNA adduct levels under three different conditions: (1) following a 48 h pretreatment with DIM, media was removed, cells were rinsed with PBS, and incubated for 6 h in media containing tritiated AFB but no DIM; (2) following a 48 h pretreatment with DIM, media was removed, cells were rinsed with PBS, and incubated for an additional 6 h in media containing tritiated AFB and DIM; (3) following a 48 h treatment with vehicle only (no DIM), media was removed, cells were rinsed with PBS, and incubated for an additional 6 h in media containing tritiated AFB and DIM. DIM was applied at 10μM. Condition 1 is designed to detect transcriptional effects, condition 3 detects potential enzyme inhibition effects, and condition 2 detects the overall effect of both. Conditions 1, 2, and 3 were compared to an analogous treatment without DIM application, which served as control (equal to 100%), for example, following a 48 h treatment with vehicle only (no DIM), media was removed, cells were rinsed with PBS, and incubated for an additional 6 h in media containing tritiated AFB only (no DIM). AFB-DNA adduct levels are expressed as percentages of control and represent means and SDs from three independent experiments (e.g., hepatocytes from three individual preparations). Conditions 1 and 2 were not significantly different from each other, but each was different from control (p ≤ 0.05), marked as “*.” Condition 3 was significantly different from conditions 1 and 2 (p ≤ 0.05), but not from the control, marked as “#.”