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

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.

Quercetin, Epigallocatechin Gallate, Curcumin, and Resveratrol: From Dietary Sources to Human MicroRNA Modulation

“…Since modulation of miRNA expression in cancer cells could be a therapeutic strategy, EGCG's biochemical effects were also studied in cancer. EGCG was able to upregulate miR-140-3p and miR-221 in melanoma and hepatoma cell lines, respectively [106,107] inhibiting osteopontin in induced liver fibrosis [107]. Similar results for miR-140-3p were obtained under EGCG treatment in chondrocyte [102].…”

Molecular Pathogenesis of Chlamydia Disease Complications: Epithelial-Mesenchymal Transition and Fibrosis

“…In addition, miR-203 targets the EMT-and cell invasion-promoting transcription factor Snail2 (Slug) (34) and SMAD3 (33,34) to prevent fibrosis. Furthermore, among the key downregulated miRNAs, miR-185 targets TGF-␤ and collagen type I to control tissue fibrosis (6,35) and miR-221 targets fibrosis-promoting osteopontin, which is also the target of the polyphenol epigallocatechin-3-gallate (EGCG), which is found in green tea and upregulates miR-221 (36). On the other hand, miR-9 is a key fibrogenic and oncogenic miRNA that targets E-cadherin and the tumor suppressor and transcription SRY-box 7 (SOX7) of the SOX transcription factor family (8,37).…”

The Ameliorative Potential of Probiotics and/or Silymarin on Thioacetamide Induced Hepatotoxicity in Rats: Histological and Immunohistochemical Study

“…Such finding suggests that probiotics and/or silymarin enhance the regeneration of TAA-intoxicated livers via increasing the expression of ki-67 (proliferation marker) that is critical tool in evaluation of liver regeneration (Gerlach et al, 1997;Pizem et al, 2001). On contrary, Arffa et al (2016), stated that livers of TAA intoxicated rats have increased ki-67 expression than treated groups. The findings of ki-67 immunolabeling were interesting as it revealed a higher regeneration activity of using silymarin and combination of silymarin with probiotics in treatment of TAA intoxicated liver than using probiotics alone.…”