Relative Ability of Dietary Compounds to Modulate Nuclear Factor-κB Activity as Assessed in a Cell-Based Reporter System

Abstract

The ability of various dietary compounds to modulate the activity of the transcription factor nuclear factor κB(NF-κB) was examined using a cell-based reporter system. NF-κB is central to the response of cells to stress and has been linked to cancer. HCT 116 (human colon carcinoma) and HepG2 (human liver carcinoma) cell lines were stably transfected with a NF-κB luciferase reporter vector. The reporter cell lines were preincubated with different concentrations (0–50 µM) of ascorbic acid, epigallocatechin gallate, genistein, quercetin, naringenin, and resveratrol for varying periods of times (1–12 hours), after which the NF-κB inducer tumor necrosis factor-α (TNF-α) was added (4–8 ng/mL) for 4 hours. Compound alone, without TNF-α, did not alter luciferase activity. Levels of TNF-α-induced luciferase (NF-κB) activity varied depending on compound type and concentration, whereas preincubation time and cell type contributed less. Significant changes in luciferase(NF-κB) activity were detected for some of the compounds at more physiological concentrations (1–10 µM). Our data suggest that dietary modulation of NF-κB activity involves distinct mechanisms, depending on compound type and concentration. More generally, this approach can be utilized for analyzing dietary compounds for effects on specific cellular factors over a range of concentrations and incubation times, in combination, and in different cell types.