Green tea catechin increases cholesterol 7a‐hydroxylase mRNA and promoter activity in HepG2 cells

Abstract

In the present study, we investigated the effect of green tea catechins on the mRNA level and promoter activity of CYP7A1 gene in human hepatocellular blastoma cells (HepG2). The CYP7A1 mRNA level was measured using real time PCR. The −1312/+358 bp of CYP7A1 promoter was subcloned into the pGL3-Basic vector that includes luciferase as a reporter gene. The CYP7A1 promoter/luciferase chimeric plasmid was transfected into HepG2 cells using superfect. Different kinds of catechin, (−)-epicatechin gallate (ECG), (−)-epigallocatechin-3-gallate (EGCG), (−)-epigallocatechin (EGC), and (−)-epicatechin (EC) up-regulated the CYP7A1 mRNA level by 5.5-, 4.2-, 2.9- and 1.9-fold, respectively, compared to the control. Also, ECG or EGCG significantly increased CYP7A1 promoter (−1312/+358 bp) activity by 6.0- and 4.0-fold, respectively compared to the control (P<0.05). The effect of EGCG, a major compound from green tea catechins, was investigated at different concentrations. The EGCG stimulated CYP7A1 gene expression showing increase the CYP7A1 mRNA level and promoter activity (P < 0.05) at dose-dependent manner. These results suggest that the expression of CYP7A1 gene, the rate-limiting enzyme in regulating cholesterol metabolism, may be up-regulated by green tea catechin, at the transcriptional level through the promoter activation. *This work was supported by research grants from the Korea Science and Engineering Foundation (M10510130005-05N1013-00500)