MiR-21 Simultaneously Regulates ERK1 Signaling in HSC Activation and Hepatocyte EMT in Hepatic Fibrosis

Abstract

BackgroundMicroRNA-21 (miR-21) plays an important role in the pathogenesis and progression of liver fibrosis. Here, we determined the serum and hepatic content of miR-21 in patients with liver cirrhosis and rats with dimethylnitrosamine-induced hepatic cirrhosis and examined the effects of miR-21 on SPRY2 and HNF4α in modulating ERK1 signaling in hepatic stellate cells (HSCs) and epithelial-mesenchymal transition (EMT) of hepatocytes.MethodsQuantitative RT-PCR was used to determine miR-21 and the expression of SPRY2, HNF4α and other genes. Immunoblotting assay was carried out to examine the expression of relevant proteins. Luciferase reporter assay was performed to assess the effects of miR-21 on its predicted target genes SPRY2 and HNF4α. Primary HSCs and hepatocytes were treated with miR-21 mimics/inhibitors or appropriate adenoviral vectors to examine the relation between miR-21 and SPRY2 or HNF4α. ResultsThe serum and hepatic content of miR-21 was significantly higher in cirrhotic patients and rats. SPRY2 and HNF4α mRNA levels were markedly lower in the cirrhotic liver. MiR-21 overexpression was associated with enhanced ERK1 signaling and EMT in liver fibrosis. Luciferase assay revealed suppressed SPRY2 and HNF4α expression by miR-21. Ectopic miR-21 stimulated ERK1 signaling in HSCs and induced hepatocyte EMT by targeting SPRY2 or HNF4α. Downregulating miR-21 suppressed ERK1 signaling, inhibited HSC activation, and blocked EMT in TGFβ1-treated hepatocytes.ConclusionsMiR-21 modulates ERK1 signaling and EMT in liver fibrosis by regulating SPRY2 and HNF4α expression. MiR-21 may serve as a potentially biomarker as well as intervention target for hepatic cirrhosis.

Stress-activatedmiR-21/miR-21*in hepatocytes promotes lipid and glucose metabolic disorders associated with high-fat diet consumption

“…Similar deregulation of complex transcriptional networks by miR-21 was also previously reported by global gene expression profile in liver cancer cells 24. Restoring the expression and activity of all these miR-21 / miR-21* -dependent key factors deregulated in the liver of LImiR21KO mice fed an HFD (ie, FOXO1,49 FOXA2,50 SREBP1C,50 STAT3,51 INSIG2 and HNF4-α)52 to similar levels than those in CTRL mice fed an HFD is technically very challenging. Alternatively, complete inhibition of a candidate target of miR-21 / miR-21* , through genetic deletion or pharmacological inhibition, can lead to cellular effects greatly exceeding the fine regulation of these factors by miRNAs.…”

MicroRNA-17-5p activates hepatic stellate cells through targeting of Smad7

“…For example, ectopic miR-21 stimulates extracellular signal-regulated kinase 1 (ERK1) signaling in HSCs and induces hepatocyte epithelial-mesenchymal transition (EMT) by targeting sprouty2 (SPRY2) or hepatocyte nuclear factor 4α (HNF4α). 10 Overexpression of miR-29b suppresses cell viability and expression of α-SMA in activated HSCs. 11 Previously, we demonstrated that curcumin upregulates miR-29b expression, leading to silencing of DNA methyltransferase 3b (DNMT3b) and loss of phosphatase and tensin homolog deleted on chromosome 10 (PTEN) methylation, which contributes to suppression of activated HSCs.…”

MicroRNAs in the Communication between Cancer Associated Fibroblasts (CAF) and Cancer Cells

“…[25] Clinical expression data for PSCs have not been published yet, but for HSCs and liver fibrosis several investigations are available. The hepatic contents of miR-21 [27,28], miR-33a [29] and miR200b [30] were significantly increased in liver specimens from human patients with liver fibrosis as compared to normal patients. Upregulation was also identified for miR-199a-5p/199a-3p and miR-221/222 in hepatitis C induced liver fibrosis in a fibrosis progression-dependent manner.…”

“…[35] Hepatic expression levels of miR-199a, miR-199a*, miR-200a, and miR-200b were positively associated with progression of liver fibrosis. [30,36] In liquid biopsies, levels of miR-17-5p [37], miR-21 [27], miR-33a [29] and miR-181b but not miR181a expression [38] were higher in fibrotic than in normal patients. In addition, miR-133a serum levels were increased in patients with chronic liver disease and indicative for the presence and progression of liver cirrhosis.…”

“…[9] Furthermore, miR-21 overexpression was associated with enhanced ERK1 signaling and EMT in liver fibrosis via direct suppression of SPRY2 and HNF4α expression. [27] Promotion of tumor induction and EMT was also induced by ectopic expression of miR-409 (member of a very large cluster) in prostate NFs conferring a CAF-like phenotype and leading to the release of miR-409 via extracellular vesicles. This miR also enhanced tumorigenesis through repression of tumor suppressor genes such as Ras suppressor-1 (RSU-1) and stromal antigen 2 (STAG2).…”