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Proteomic analysis of the inhibitory effect of epigallocatechin gallate on lipid accumulation in human HepG2 cells.

ABSTRACT: BACKGROUND:(-)-Epigallocatechin-3-gallate (EGCG), the most abundant catechin found in green tea, effectively reduces body weight and tissue and blood lipid accumulation. To explore the mechanism by which EGCG inhibits cellular lipid accumulation in free fatty acid (FFA) induced HepG2 cell culture, we investigated the proteome change of FFA-induced HepG2 cells exposed to EGCG using two-dimensional gel electrophoresis and mass spectrometry. RESULTS:In this study, 36 protein spots showed a significant change in intensity by more than 1.5-fold from the control group to the FFA group and from the FFA group to the FFA + EGCG group. Among them, 24 spots were excised from gels and identified by LC-MS/MS. In total, 18 proteins were successfully identified. All identified proteins were involved in lipid metabolism, glycometabolism, antioxidant defense, respiration, cytoskeleton organization, signal transduction, DNA repair, mRNA processing, iron storage, or were chaperone proteins. This indicated that these physiological processes may play roles in the mechanism of inhibition of lipid accumulation by EGCG in FFA-induced HepG2 cells. Western blotting analysis was used to verify the expression levels of differentially expressed proteins, which agree with the proteomic results. CONCLUSIONS:From the proteomic analysis, we hypothesized that EGCG reduced cellular lipid accumulation in FFA-induced HepG2 cells through the activation of AMP-activated protein kinase (AMPK) resulting from the generation of reactive oxygen species (ROS). The induction of ROS may be a result of EGCG regulation of the antioxidant defense system. Activation of AMPK shifted some FFA toward oxidation, away from lipid and triglyceride storage, and suppressed hepatic gluconeogenesis. The findings of this study improve our understanding of the molecular mechanisms of inhibition of lipid accumulation by EGCG in HepG2 cells.

SUBMITTER: Liu Z

PROVIDER: S-EPMC3723827 | biostudies-literature | 2013 Jul

REPOSITORIES: biostudies-literature

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Proteomic analysis of the inhibitory effect of epigallocatechin gallate on lipid accumulation in human HepG2 cells.

Liu Zhonghua Z Li Qin Q Huang Jianan J Liang Qionglin Q Yan Yujun Y Lin Haiyan H Xiao Wenjun W Lin Yong Y Zhang Sheng S Tan Bin B Luo Guoan G

Proteome science 20130718 1

<h4>Background</h4>(-)-Epigallocatechin-3-gallate (EGCG), the most abundant catechin found in green tea, effectively reduces body weight and tissue and blood lipid accumulation. To explore the mechanism by which EGCG inhibits cellular lipid accumulation in free fatty acid (FFA) induced HepG2 cell culture, we investigated the proteome change of FFA-induced HepG2 cells exposed to EGCG using two-dimensional gel electrophoresis and mass spectrometry.<h4>Results</h4>In this study, 36 protein spots sh ...[more]

PMID: 23866759

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Project description:Inflammatory Breast Cancer (IBC) is a highly aggressive form of cancer characterized by high rates of proliferation, lymphangiogenesis and metastasis, and an overall poor survival. As regular green tea consumption has been associated with improved prognosis of breast cancer patients, including decreased risk of recurrence, here the effects of the green tea polyphenol epigallocatechin-3-gallate (EGCG) were tested on two IBC lines: SUM-149 and SUM-190. EGCG decreased expression of genes that promote proliferation, migration, invasion, and survival. Consistently, growth, invasive properties, and survival of IBC cells were reduced by EGCG treatment. EGCG also reduced lymphangiogenesis-promoting genes, in particular VEGF-D. Conditioned media from EGCG-treated IBC cells displayed decreased VEGF-D secretion and reduced ability to promote lymphangiogenesis in vitro as measured by hTERT-HDLEC lymphatic endothelial cell migration and tube formation. Tumorsphere formation by SUM-149 cells was robustly inhibited by EGCG, suggesting effects on self-renewal ability. Stem-like SUM-149 cells with high aldehyde dehydrogenase (ALDH) activity, previously implicated in poor patient prognosis, were isolated. EGCG treatment reduced growth and induced apoptosis of the stem-like SUM-149 cells in culture. In an orthotopic mouse model, EGCG decreased growth of pre-existing tumors derived from ALDH-positive stem-like SUM-149 cells and their expression of VEGF-D, which correlated with a significant decrease in peritumoral lymphatic vessel density. Thus, EGCG inhibits the overall aggressive IBC phenotype. Reduction of the stem-like cell compartment by EGCG may explain the decreased risk of breast cancer recurrence among green tea drinkers. Recent clinical trials demonstrate the efficacy of green tea polyphenol extracts in treatment of prostate cancer and lymphocytic leukemia with low toxicity. Given the poor prognosis of IBC patients, our findings suggest further exploration of EGCG or green tea in combinatorial treatments against active IBC disease or in maintenance regimens to avoid recurrence is warranted.

Dataset Information

Proteomic analysis of the inhibitory effect of epigallocatechin gallate on lipid accumulation in human HepG2 cells.

Publications

Proteomic analysis of the inhibitory effect of epigallocatechin gallate on lipid accumulation in human HepG2 cells.

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