Nicotinic acid, lauric acid and kaempferol abolish ATP-binding cassette transporter subfamily A member 1 (ABCA1) down-regulation by TNF-? in hepatocarcinoma HepG2 cell line.

The aim of this study was to investigate the effect of different concentrations of antioxidants on ABCA1 mRNA expression in TNF-α stimulated hepatocarcinoma (HepG2) cell line. TNF- α-stimulated cells were treated with 1 μM, 5 μM, 10 μM and 20 μM of nicotinic acid, lauric acid or kaempferol for 24 h, respectively. Real time RT-PCR was carried out to analyze the expression of the genes. Relative ABCA1 mRNA levels were normalized to beta-actin and their relative expression to untreated cells was analyzed using delta-delta CT method. Here we show that ABCA1 mRNA levels were significantly suppressed by 20 ng/ml of TNF-α, but all three antioxidants were able to antagonize this suppressive effect of TNF-α. High doses (20 μM) of the antioxidants significantly up-regulated the ABCA1 gene expression. This study successfully profiled that all the three antioxidants were able to alleviate the downregulatory effect of TNF-α on ABCA1 transcript level in HepG2 cells. Although stimulation with kaempferol alone induced ABCA1 expression to high levels, its ability to reduce TNF-α inhibitory response was the weakest amongst the three antioxidants