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PLoS One. 2016 Dec 9;11(12):e0167435. doi: 10.1371/journal.pone.0167435. eCollection 2016.

Epigallocatechin-3-Gallate Upregulates miR-221 to Inhibit Osteopontin-Dependent Hepatic Fibrosis.

Author information

1
Department of Surgery, Loyola University Medical Center, Maywood, IL, United States of America.
2
Department of Biochemistry, Faculty of Pharmacy, Mansoura University, Mansoura, Egypt.
3
Department of Pharmaceutical Chemistry, University of Tabuk, Tabuk, Saudi Arabia.
4
Division of Gastroenterology and Hepatology, Medical University of South Carolina, Charleston, South Carolina, United States of America.
5
Section of Gastroenterology, Ralph H Johnson Veteran Affairs Medical Center, Charleston, South Carolina, United States of America.

Abstract

Osteopontin (OPN) promotes hepatic fibrosis, and developing therapies targeting OPN expression in settings of hepatic injury holds promise. The polyphenol epigallocatechin-3-gallate (EGCG), found in high concentrations in green tea, downregulates OPN expression through OPN mRNA degradation, but the mechanism is unknown. Previous work has shown that microRNAs can decrease OPN mRNA levels, and other studies have shown that EGCG modulates the expression of multiple microRNAs. In our study, we first demonstrated that OPN induces hepatic stellate cells to transform into an activated state. We then identified three microRNAs which target OPN mRNA: miR-181a, miR-10b, and miR-221. In vitro results show that EGCG upregulates all three microRNAs, and all three microRNAs are capable of down regulating OPN mRNA when administered alone. Interestingly, only miR-221 is necessary for EGCG-mediated OPN mRNA degradation and miR-221 inhibition reduces the effects of EGCG on cell function. In vivo experiments show that thioacetamide (TAA)-induced cell cytotoxicity upregulates OPN expression; treatment with EGCG blocks the effects of TAA. Furthermore, chronic treatment of EGCG in vivo upregulates all three microRNAs equally, suggesting that in more chronic treatment all three microRNAs are involved in modulating OPN expression. We conclude that in in vitro and in vivo models of TAA-induced hepatic fibrosis, EGCG inhibits OPN-dependent injury and fibrosis. EGCG works primarily by upregulating miR-221 to accelerate OPN degradation. EGCG may therefore have utility as a protective agent in settings of liver injury.

PMID:
27935974
PMCID:
PMC5147893
DOI:
10.1371/journal.pone.0167435
[Indexed for MEDLINE]
Free PMC Article

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