β-catenin is overexpressed in hepatic fibrosis and blockage of Wnt/β-catenin signaling inhibits hepatic stellate cell activation

Role of EZH2 in liver disease

Overexpression of enhancer of zeste homolog 2 (EZH2) protein has been found in several malignant tumor tissues and is closely related to the degree of tumor differentiation, clinical stage, tumor size, and prognosis. The latest research shows that overexpression of EZH2 is related not only with immunoregulation but also with the replication of hepatitis B virus, the occurrence of non-alcoholic fatty liver disease, and the progress of liver fibrosis, which may become an important subject in the field of liver disease research. This paper reviews the role of EZH2 in some liver diseases and its potential application in treatment of these diseases in recent ten years.

SENP2 alleviates CCl4-induced liver fibrosis by promoting activated hepatic stellate cell apoptosis and reversion

SUMOylation and deSUMOylation, a dynamic process, is proved to be involved in various fibrotic diseases. Here, we found SENP2, one of deSUMOylation protease family member, was decreased in CCl₄-induced mice fibrotic liver tissues, primary HSCs and restored after spontaneously recovery. In addition, HSC-T6 cells with TGF-β1 treatment resulted in a significant reduction of SENP2. Ectopic expression of SENP2 hindered cells activation and proliferation induced by TGF-β1 while knockdown of SENP2 showed an opposite effect. Importantly, SENP2 promoted apoptosis of HSC-T6 cells activated by TGF-β1. Furthermore, restoration of SENP2 was observed in inactivated HSCs after adipogenic differentiation mixture (MDI) treatment. Inadequate SENP2 inhibited the reversion of HSC-T6 cells, featured as aberrant expressions of α-SMA and col1a1, two markers of liver fibrosis. It has been reported SENP2 was a suppressant regulator of Wnt/β-catenin signal pathway. Similarly, we found SENP2 has a negative effect on β-catenin as well as its downstream genes C-myc and CyclinD1 in liver fibrosis. Collectively, our data indicated SENP2 may be involved in HSCs apoptosis and reversion in liver fibrosis.

Changes in the microarchitecture of the pancreatic cancer stroma are linked to neutrophil-dependent reprogramming of stellate cells and reflected by diffusion-weighted magnetic resonance imaging

In pancreatic cancer (PDAC) intratumor infiltration of polymorphonuclear neutrophils (PMN) is associated with histologically apparent alterations of the tumor growth pattern. The aim of this study was to examine possible associations between PMN infiltration, tumor microarchitecture, and water diffusivity in diffusion-weighted magnetic resonance imaging (DW-MRI), and to further asses the underlying mechanisms.

Methods: DW-MRI was performed in 33 PDAC patients prior to surgery. In parallel, tissue specimen were examined histologically for growth pattern, azurocidin-positive PMN infiltrates, and the presence of alpha-smooth muscle actin (α-SMA) and metalloproteinase 9 (MMP9)-positive myofibroblastic cells. For confirmation of the histological findings, a tissue microarray of a second cohort of patients (n=109) was prepared and examined similarly. For in vitro studies, the pancreatic stellate cell line RLT was co-cultivated either with isolated PMN, PMN-lysates, or recombinant azurocidin and characterized by Western blot, flow cytometry, and proteome profiler arrays.

Results: Tumors with high PMN density showed restricted water diffusion in DW-MRI and histologic apparent alterations of the tumor microarchitecture (microglandular, micropapillary, or overall poorly differentiated growth pattern) as opposed to tumors with scattered PMN. Areas with altered growth pattern lacked α-SMA-positive myofibroblastic cells. Tissue microarrays confirmed a close association of high PMN density with alterations of the tumor microarchitecture and revealed a significant association of high PMN density with poor histologic grade of differentiation (G3). In vitro experiments provided evidence for direct effects of PMN on stellate cells, where a change to a spindle shaped cell morphology in response to PMN and to PMN-derived azurocidin was seen. Azurocidin incorporated into stellate cells, where it associated with F-actin. Down-regulation of α-SMA was seen within hours, as was activation of the p38-cofilin axis, up-regulation of MMP9, and acquisition of intracellular lipid droplets, which together indicate a phenotype switch of the stellate cells.

Conclusion: In PDAC, PMN infiltrates are associated with alterations of the tumor microarchitecture. As a causal relationship, we propose a reprogramming of stellate cells by PMN-derived azurocidin towards a phenotype, which affects the microarchitecture of the tumor.

Wnt/β-Catenin Signaling in Liver Development, Homeostasis, and Pathobiology

The liver is an organ that performs a multitude of functions, and its health is pertinent and indispensable to survival. Thus, the cellular and molecular machinery driving hepatic functions is of utmost relevance. The Wnt signaling pathway is one such signaling cascade that enables hepatic homeostasis and contributes to unique hepatic attributes such as metabolic zonation and regeneration. The Wnt/β-catenin pathway plays a role in almost every facet of liver biology. Furthermore, its aberrant activation is also a hallmark of various hepatic pathologies. In addition to its signaling function, β-catenin also plays a role at adherens junctions. Wnt/β-catenin signaling also influences the function of many different cell types. Due to this myriad of functions, Wnt/β-catenin signaling is complex, context-dependent, and highly regulated. In this review, we discuss the Wnt/β-catenin signaling pathway, its role in cell-cell adhesion and liver function, and the cell type-specific roles of Wnt/β-catenin signaling as it relates to liver physiology and pathobiology.

Hepatic stellate cells as key target in liver fibrosis

Progressive liver fibrosis, induced by chronic viral and metabolic disorders, leads to more than one million deaths annually via development of cirrhosis, although no antifibrotic therapy has been approved to date. Transdifferentiation (or "activation") of hepatic stellate cells is the major cellular source of matrix protein-secreting myofibroblasts, the major driver of liver fibrogenesis. Paracrine signals from injured epithelial cells, fibrotic tissue microenvironment, immune and systemic metabolic dysregulation, enteric dysbiosis, and hepatitis viral products can directly or indirectly induce stellate cell activation. Dysregulated intracellular signaling, epigenetic changes, and cellular stress response represent candidate targets to deactivate stellate cells by inducing reversion to inactivated state, cellular senescence, apoptosis, and/or clearance by immune cells. Cell type- and target-specific pharmacological intervention to therapeutically induce the deactivation will enable more effective and less toxic precision antifibrotic therapies.

Snail1 is positively correlated with atrial fibrosis in patients with atrial fibrillation and rheumatic heart disease

The present study investigated the association between Snail1 and atrial fibrosis in patients with atrial fibrillation (AF) and rheumatic heart disease (RHD) and to determine the possible mechanism underlying this interrelation. A total of 19 patients were included in the current study and were divided into two groups: A sinus rhythm (SR) group (n=9) and an AF group (n=10). All patients underwent heart valve replacement surgery, during which ~200 mg right atrium tissue was obtained. Hematoxylin and eosin and Masson's trichrome-stained sections were used to evaluate the morphological changes of cardiomyocytes and the level of fibrosis. Immunohistochemistry was applied to observe the location and expression of Snail1. Reverse transcription-quantitative polymerase chain reaction was used to measure Snail1 mRNA levels. Western blotting was used to determine changes in the expression of Snail1, as well as in the expression of proteins involved in the Wnt pathway, including Wnt1, Wnt 3a, Wnt8a, Wnt5a and Wnt11. Compared with the SR group, expanded cardiomyocytes and higher collagen deposition was detected in the atrial tissue of the AF group. The expression of Snail1 mRNA and protein was significantly higher in the AF group than in the SR group (P<0.05). Additionally, the expression of Wnt1, 3a and 8a in the canonical Wnt signaling pathway, and Wnt5a and 11 in the noncanonical Wnt signaling pathway were significantly increased in the AF group. Furthermore, the phosphorylation level of glycogen synthase kinase 3β (GSK3β) and the levels of β-catenin and GSK3β were significantly increased in the AF group compared with the SR group (P<0.05). Snail1 may be involved in the development and maintenance of atrial fibrosis in patients with atrial fibrillation and rheumatic heart disease and may be developed as a novel biomarker to evaluate myocardial fibrosis in the future. Additionally, the current study suggests that the Wnt signaling pathway may participate in the process of increased Snail1 expression and atrial fibrosis in patients with AF and RHD.

Oxidored-nitro domain-containing protein 1 promotes liver fibrosis by activating the Wnt/β-catenin signaling pathway in vitro

Hepatic fibrosis is a characteristic of various types of chronic liver diseases, and may further develop into liver cirrhosis and liver cancer. Oxidored‑nitro domain‑containing protein 1 (NOR1) expression levels are greater in hepatitis, cirrhosis and hepatocellular carcinoma samples compared with from normal liver samples. However, the importance of NOR1 in liver fibrosis remains to be elucidated. The present study aimed to investigate the effect of NOR1 on the proliferation and matrix expression of human hepatic stellate cells (HSCs) in vitro. Additionally, the molecular mechanisms underlying the role of NOR1 in the activation of HSCs was investigated. The present study determined that transforming growth factor β1 (TGF‑β1) may induce NOR1 expression in HSCs in a dose‑dependent manner, as determined by reverse transcription‑quantitative polymerase chain reaction and western blot analysis. NOR1‑small hairpin (sh)RNA was transfected into TGF‑β1‑treated HSCs to knock down NOR1. The MTT assay revealed that TGF‑β1‑induced cell proliferation was significantly inhibited in the NOR1‑shRNA group. In addition, NOR1 knockdown significantly inhibited TGF‑β1‑induced protein expression of fibrosis indexes, including collagen 1, 3 and α‑smooth muscle actin (α‑SMA). Subsequently, NOR1‑pcDNA3.1 was transfected into HSCs to overexpress NOR1. It was revealed that NOR1 overexpression may activate the Wnt/β‑catenin pathway in HSCs. The gain‑of function experiments demonstrated that NOR1 overexpression promoted cell proliferation and the expression of fibrosis indexes; however, these effects may be attenuated by dickkopf‑1, an inhibitor of the Wnt/β‑catenin signaling pathway. In conclusion, the present study demonstrated that NOR1 activates HSCs and contributes to liver fibrosis in vitro and this effect was achieved through the activation of the Wnt/β‑catenin pathway. Therefore, the current study may provide a novel target for the treatment of chronic liver diseases.

Molecular mechanism of miR-154 targeting MMP-9 by regulating Wnt/β-catenin pathway in liver fibrosis

This research aimed to study the mechanism of miR-154 targeting MMP-9 by regulating Wnt/β-catenin pathway the liver fibrosis. Dual luciferase reports were performed to analyze interactions between miR-154 and MMP-9. Pathology of liver fibrosis was observed by HE stains. The expression of β-catenin, Dsh, APC, GSK3 and MMP9 was detected by Western blot and FQ PCR. The Cell proliferation assay indicated miR-154 inhibited cell proliferation. The results of Western blot and FQ PCR show that mRNA and protein levels of β-catenin, Dsh, APC, GSK3, MMP9 decreased significantly, when miR-154 overexpressed in liver fibrosis, while they increased significantly in miR-154 inhibitors group (P < 0.05). The luciferase's result displayed the weakened wild-type fluorescents, while no significant differences in mutant fluorescents' strength, compared with the control models. HE's dyeing results the obviously increased in fibrosis, compared inhibitor group with model group. It was concluded that miR-154 inhibited Wnt/β-catenin's pathway by targeting MMP-9, slowing the process of liver fibrosis.

Effect of probiotics on immunity in children with enteritis

AIM

To investigate the clinical effects of probiotics in children with rotavirus enteritis and the effect on immune function.

METHODS

Ninety patients with rotavirus enteritis were randomly divided into either a control group or an observation group. The control group was treated with immunoglobulins. The observation group was treated with probiotics. The levels of T lymphocyte subsets were measured by flow cytometry before and after treatment. The clinical effects of the two groups were compared.

RESULTS

After treatment for 7 d, times to stopping diarrhea (2.43 d ± 0.49 d), vomiting (1.379 d ± 0.24 d), and fever (1.429 d ± 0.47 d) and hospitalization time (3.219 d ± 1.02 d) were significantly shorter in the observation group than in the control group (t = 20.53, 18.99, 22.15, 19.35, P < 0.05); the levels of CD3⁺ T cells (67.42 ± 10.92 vs 58.51 ± 11.24), CD4⁺ T cells (36.43 ± 6.32 vs 32.41 ± 5.46) and CD4⁺/CD8⁺ ratio (1.43 ± 0.3 vs 1.21 ± 0.32) were significantly higher in the observation group than in the control group (P < 0.05), but the level of CD8⁺ T cells in the observation group was significantly lower than that in the control group (23.41±4.53 vs 27.43±4.01, P < 0.05).

CONCLUSION

The use of probiotics in children with rotavirus enteritis can reduce the incidence of microflora dysfunction and complications. Immunoglobulins can shorten the hospitalization time and should be selected according to the situation of each patient.

EZH2-mediated repression of Dkk1 promotes hepatic stellate cell activation and hepatic fibrosis

EZH2, a histone H3 lysine‐27‐specific methyltransferase, is involved in diverse physiological and pathological processes including cell proliferation and differentiation. However, the role of EZH2 in liver fibrosis is largely unknown. In this study, it was identified that EZH2 promoted Wnt pathway‐stimulated fibroblasts in vitro and in vivo by repressing Dkk‐1, which is a Wnt pathway antagonist. The expression of EZH2 was increased in CCl₄‐induced rat liver and primary HSCs as well as TGF‐β1‐treated HSC‐T6, whereas the expression of Dkk1 was reduced. Silencing of EZH2 prevented TGF‐β1‐induced proliferation of HSC‐T6 cells and the expression of α‐SMA. In addition, knockdown of Dkk1 promoted TGF‐β1‐induced activation of HSCs. Moreover, silencing of EZH2 could restore the repression of Dkk‐1 through trimethylation of H3K27me3 in TGF‐β1‐treated HSC‐T6 cells. Interestingly, inhibition of EZH2 had almost no effect on the activation of HSC when Dkk1 was silenced. Collectively, EZH2‐mediated repression of Dkk1 promotes the activation of Wnt/β‐catenin pathway, which is an essential event for HSC activation.

LncRNA-ATB/microRNA-200a/β-catenin regulatory axis involved in the progression of HCV-related hepatic fibrosis

OBJECTIVE(S)

Long noncoding RNAs (lncRNAs)-activated by transforming growth factor beta (lncRNA-ATB) is known to be involved in the invasion of hepatocellular carcinoma by regulating target genes of miR-200a. However, the role and molecular mechanisms of lncRNA-ATB/miR-200a in HCV-related liver fibrosis remains unclear. In this study, we examined the expression of lncRNA-ATB/miR-200a, and their target gene β-Catenin in liver tissues of HCV patients and hepatic stellate cells (HSCs) to elucidate the possible role of lncRNA-ATB/miR-200a axis in HSC activation and development of liver fibrosis.

MATERIALS AND METHODS

Liver tissues were obtained by biopsy or surgery from eighteen HCV patients with severe liver fibrosis and six healthy subjects (control). Conditioned media (CM) from cultured HepG2-CORE cells (HepG2 cells stably expressing HCV core protein) were used to treat LX-2 cells. The binding sites between lncRNA-ATB/miR-200a and β-catenin were predicted and then verified by a dual luciferase reporter assay. The effect of lncRNA-ATB/miR-200a/β-catenin on HSC activation was assessed by examining the expression of alpha-smooth muscle actin (α-SMA) and collagen type 1 alpha 1 (Col1A1) in HSCs. Further, the regulatory role of lncRNA-ATB on HSC activation and miR-200a/β-catenin expression was assessed by using siRNA-mediated knockdown of lncRNA-ATB.

RESULTS

LncRNA-ATB was up-regulated in fibrotic liver tissues and activated LX-2 cells treated with CM from HepG2-CORE cells. Dual luciferase reporter assays confirmed that lncRNA-ATB contained common binding sites for miR-200a and β-catenin. Decreased expression of miR-200a and increased expression of β-catenin were observed in liver tissues of patients with HCV-related hepatic fibrosis and activated HSCs. Knockdown of lncRNA-ATB could down-regulate β-catenin expression by up-regulating the endogenous miR-200a and suppress the activation of LX-2 cells.

CONCLUSION

LncRNA-ATB/miR-200a/β-catenin regulatory axis likely contributed to the development of liver fibrosis in HCV patients. Knockdown of lncRNA-ATB might be a novel therapeutic target for HCV-related liver fibrosis.

Diosmin attenuates radiation-induced hepatic fibrosis by boosting PPAR-γ expression and hampering miR-17-5p-activated canonical Wnt-β-catenin signaling

BACKGROUND

Liver fibrosis is one of the major complications from upper right quadrant radiotherapy. MicroRNA-17-5p (miR-17-5p) is hypothesized to act as a regulator of hepatic stellate cell (HSCs) activation by activation of the canonical Wnt-β-catenin pathway. Diosmin (Dios), a citrus bioflavonoid, is known to possess potent antioxidant, anti-inflammatory, and anti-apoptotic properties.

PURPOSE

To explore the molecular mechanisms that underlie radiation-induced liver fibrosis, and to evaluate the possible influence of Dios on the miR-17-5p-Wnt-β-catenin signaling axis during fibrogenesis provoked by irradiation (IRR) in rats. Also, the effect of Dios on hepatic peroxisome proliferator activated receptor-γ (PPAR-γ) expression as a regulator for HSC activation was considered.

METHODS

We administered 100 mg·(kg body mass)^-1·day^-1 (per oral) of Dios were administered to IRR-exposed rats (overall dose of 12 Gy on 6 fractions of 2 Gy each) for 6 successive weeks.

RESULTS

Data analysis revealed that Dios treatment mitigated oxidative stress, enhanced antioxidant defenses, alleviated hepatic inflammatory responses, abrogated pro-fibrogenic cytokines, and stimulated PPAR-γ expression. Dios treatment repressed the miR-17-5p activated Wnt-β-catenin signaling induced by IRR. Moreover, Dios treatment restored the normal hepatic architecture and reversed pathological alterations induced by IRR.

CONCLUSION

We hypothesize that the stimulation of PPAR-γ expression and interference with miR-17-5p activated Wnt-β-catenin signaling mediates the antifibrotic properties of Dios.

Interleukin-22 ameliorates liver fibrosis through miR-200a/beta-catenin

IL-22 ameliorates liver fibrosis by inhibiting hepatic stellate cells (HSC), and loss of miR-200a is associated with the development of liver fibrosis. The study aimed to investigate the interplay between IL-22 and miR-200a in regulating liver fibrosis in vivo and in vitro. We observed that IL-22 significantly reduced the proliferation of HSC and increased the expression of p-STAT3. β-catenin was identified as a target gene of miR-200a by luciferase reporter assay, and upregulation of miR-200a significantly attenuated the proliferation of HSC and reduced β-catenin expression. IL-22 treatment increased expression of miR-200a and decreased expression of β-catenin in HSC. The expression of p-STAT3 and miR-200a was elevated while β-catenin was decreased in fibrotic rat liver after IL-22 treatment. Expression levels of β-catenin and p-STAT3 were inversely correlated in fibrotic rat liver and HSC. Upregulation of β-catenin suppressed expression of p-STAT3 in HSC. We concluded that IL-22 inhibits HSC activation and ameliorates liver fibrosis through enhancing expression of miR-200a and reducing expression of β-catenin, suggesting there may be a crosstalk between IL-22/STAT3 and β-catenin pathway.

Improvement of Sclerodermatous Graft-Versus-Host Disease in Mice by Niclosamide

Sclerodermatous graft-versus-host disease, a frequent complication of allogeneic hematopoietic stem cell graft, shares many features with systemic sclerosis, such as production of autoantibodies and fibrosis of skin and inner organs. Recent reports on the implication of signal transducer and activator of transcription 3 and of Wnt/β-catenin in fibrosis have prompted us to investigate the effects of the inhibition of both signaling pathways in a mouse model of sclerodermatous graft-versus-host disease, using niclosamide, an anthelmintic drug, with a well-defined safety profile. Sclerodermatous graft-versus-host disease was induced in BALB/c mice by B10.D2 bone marrow and spleen cell transplantation. Mice were treated every other day, 5 days a week, for 5 weeks by niclosamide. Clinical and biological features were studied 42 days after transplantation. Niclosamide reversed clinical symptoms including alopecia, vasculitis, and diarrhea and prevented fibrosis of the skin and visceral organs. Beneficial immunological effects were also observed: niclosamide decreased the production of effector memory CD4 and CD8 T cells, T-cell infiltration of the skin and visceral organs, and decreased productions of IL-4 and IL-13, and autoimmune B-cell activation. The improvement provided by niclosamide in the mouse model of sclerodermatous graft-versus-host disease provides a rationale for the evaluation of niclosamide in the management of patients affected by systemic fibrotic disease.

Human urokinase-type plasminogen activator gene-modified bone marrow-derived mesenchymal stem cells attenuate liver fibrosis in rats by down-regulating the Wnt signaling pathway

AIM: To evaluate the therapeutic effects of bone marrow-derived mesenchymal stem cells (BMSCs) with human urokinase-type plasminogen activator (uPA) on liver fibrosis, and to investigate the mechanism of gene therapy.

METHODS: BMSCs transfected with adenovirus-mediated human urokinase plasminogen activator (Ad-uPA) were transplanted into rats with CCl₄-induced liver fibrosis. All rats were sacrificed after 8 wk, and their serum and liver tissue were collected for biochemical, histopathologic, and molecular analyzes. The degree of liver fibrosis was assessed by hematoxylin and eosin or Masson’s staining. Western blot and quantitative reverse transcription-polymerase chain reaction were used to determine protein and mRNA expression levels.

RESULTS: Serum levels of alanine aminotransferase, aminotransferase, total bilirubin, hyaluronic acid, laminin, and procollagen type III were markedly decreased, whereas the levels of serum albumin were increased by uPA gene modified BMSCs treatment. Histopathology revealed that chronic CCl4-treatment resulted in significant fibrosis while uPA gene modified BMSCs treatment significantly reversed fibrosis. By quantitatively analysing the fibrosis area of liver tissue using Masson staining in different groups of animals, we found that model animals with CCl₄-induced liver fibrosis had the largest fibrotic area (16.69% ± 1.30%), while fibrotic area was significantly decreased by BMSCs treatment (12.38% ± 2.27%) and was further reduced by uPA-BMSCs treatment (8.31% ± 1.21%). Both protein and mRNA expression of β-catenin, Wnt4 and Wnt5a was down-regulated in liver tissues following uPA gene modified BMSCs treatment when compared with the model animals.

CONCLUSION: Transplantation of uPA gene modified BMSCs suppressed liver fibrosis and ameliorated liver function and may be a new approach to treating liver fibrosis. Furthermore, treatment with uPA gene modified BMSCs also resulted in a decrease in expression of molecules of the Wnt signaling pathway.

Hepatoprotective and Anti-fibrotic Agents: It's Time to Take the Next Step

Hepatic fibrosis and cirrhosis cause strong human suffering and necessitate a monetary burden worldwide. Therefore, there is an urgent need for the development of therapies. Pre-clinical animal models are indispensable in the drug discovery and development of new anti-fibrotic compounds and are immensely valuable for understanding and proofing the mode of their proposed action. In fibrosis research, inbreed mice and rats are by far the most used species for testing drug efficacy. During the last decades, several hundred or even a thousand different drugs that reproducibly evolve beneficial effects on liver health in respective disease models were identified. However, there are only a few compounds (e.g., GR-MD-02, GM-CT-01) that were translated from bench to bedside. In contrast, the large number of drugs successfully tested in animal studies is repeatedly tested over and over engender findings with similar or identical outcome. This circumstance undermines the 3R (Replacement, Refinement, Reduction) principle of Russell and Burch that was introduced to minimize the suffering of laboratory animals. This ethical framework, however, represents the basis of the new animal welfare regulations in the member states of the European Union. Consequently, the legal authorities in the different countries are halted to foreclose testing of drugs in animals that were successfully tested before. This review provides a synopsis on anti-fibrotic compounds that were tested in classical rodent models. Their mode of action, potential sources and the observed beneficial effects on liver health are discussed. This review attempts to provide a reference compilation for all those involved in the testing of drugs or in the design of new clinical trials targeting hepatic fibrosis.

Wnts talking with the TGF-β superfamily: WISPers about modulation of osteoarthritis

The Wnt signalling pathway is gaining increasing attention in the field of joint pathologies, attributable to its role in the development and homeostasis of the tissues found in the joint, including bone and cartilage. Imbalance in this pathway has been implicated in the development and progression of OA, and interference with the pathway might therefore depict an effective treatment strategy. Though offering multiple opportunities, it is yet to be decided which starting point will bring forth the most promising results. The complexity of the pathway and its interaction with other pathways (such as the TGF-β signalling pathway, which also has a central role in the maintenance of joint homeostasis) means that acting directly on proteins in this signalling cascade entails a high risk of undesired side effects. Therefore, interference with Wnt-induced proteins, such as WISP1, might be an overall more effective and safer therapeutic approach to inhibit the pathological events that take place during OA.

MiR-146a-5p suppresses activation and proliferation of hepatic stellate cells in nonalcoholic fibrosing steatohepatitis through directly targeting Wnt1 and Wnt5a

Nonalcoholic fibrosing steatohepatitis is a uniform process throughout nonalcoholic fatty liver disease (NAFLD). MicroRNAs (miRNAs) have been suggested to modulate cellular processes in liver diseases. However, the functional role of miRNAs in nonalcoholic fibrosing steatohepatitis is largely unclear. In this study, we systematically analyzed the hepatic miRNAs by microarray analysis in nonalcoholic fibrosing steatohepatitis in C57BL/6J mice induced by methionine-choline deficient (MCD) diet. We identified 19 up-regulated and 18 down-regulated miRNAs in liver with fibrosis. Among these dysregulated miRNAs, miR-146a-5p was the most significant down-regulated miRNA. Luciferase activity assay confirmed that Wnt1 and Wnt5a were both the target genes of miR-146a-5p. Hepatic miR-146a-5p was down-regulated in fibrosing steatohepatitis, but its target genes Wnt1 and Wnt5a and their consequent effectors α-SMA and Col-1 were significantly up-regulated. In addition, miR-146a-5p was downregulated, whilst Wnt1 and Wnt5a were up-regulated in the activated primary hepatic stellate cells (HSCs) compared to the quiescent primary HSCs. Overexpression of miR-146a-5p in HSCs inhibited HSC activation and proliferation, which concomitant with the decreased expressions of Wnt1, Wnt5a, α-SMA and Col-1. In conclusion, miR-146a-5p suppresses activation and proliferation of HSCs in the progress of nonalcoholic fibrosing steatohepatitis through targeting Wnt1 and Wnt5a and consequent effectors α-SMA and Col-1.

Differential Effects of Axin2 Deficiency on the Fibrogenic and Regenerative Response in Livers of Bile Duct-Ligated Mice

Background: Wnt signaling is involved in the pathogenesis of liver fibrosis. Axin2 is a negative regulator of the canonical Wnt pathway by promoting β-catenin degradation. β-Catenin-activating and loss-of-function mutations of Axin2 are thought to be functionally relevant for liver diseases and cancer. Thus, we hypothesized that Axin2 deficiency promotes fibrogenesis. Methods: As the functions and mechanisms of how Axin2/β-catenin signaling participates in the progression of liver fibrosis are unclear, we investigated the progression of liver fibrosis in Axin2-deficient mice using Axin2-LacZ reporter mice (Axin2+/-, Axin2-/-, and Axin2+/+) which underwent bile duct ligation (BDL). Results: Here, we show that the expression of Axin2 is downregulated during fibrogenesis in wild-type mice, which is consistent with a decreased expression of the reporter gene LacZ in Axin2+/- and Axin2-/- mice. Surprisingly, no alteration in active β-catenin/Wnt signaling occurs in Axin2-deficient mice upon BDL. Despite a less pronounced liver injury, Axin2 deficiency had only minor and no significant effects on the fibrogenic response upon BDL, i.e. slightly reduced hepatic stellate cell activity and collagen mRNA expression. However, livers of Axin2-/- mice shared a stronger cell proliferation both already at baseline as well as immediately after BDL. Conclusion: Our results strongly suggest, contrary to expectation, that a deficiency in Axin2 is not equivalent to an increase in active β-catenin and target genes, indicating no functional relevance of Axin2-dependent regulation of the canonical Wnt/β-catenin pathway in the progression of cholestatic liver injury. This also suggests that the negligible effects of Axin2 deficiency during fibrogenesis may be related to an alternative pathway.

Curcumin raises lipid content by Wnt pathway in hepatic stellate cell

BACKGROUND

Activation of hepatic stellate cells (HSCs) is a pivotal event in liver fibrosis, which is characterized by dramatic disappearance of lipid droplets. However, the underlying molecular mechanisms are largely unknown. We aimed to explore the role of Wnt/β-catenin pathway in HSC lipogenesis and to examine the effects of curcumin in this molecular context.

METHODS

Primary rat HSCs were cultured in vitro for experiments. The Wnt activator WAY-262611 and β-catenin activator lithium chloride (LiCl) were used to activate the pathway at distinct levels in HSCs. Cell proliferation, fibrogenic markers, intracellular lipids and triglyceride, and adipogenic transcription factors were examined in HSCs.

RESULTS

Both WAY-262611 and LiCl promoted proliferation and upregulated the expression of α-smooth muscle actin and α1(I) procollagen, but they decreased the contents of intracellular lipids and triglyceride in HSCs. Analyses of adipogenic transcription pattern showed that the two compounds reduced the expression of peroxisome proliferator-activated receptor γ, CCAAT/enhancer binding protein α, retinoid X receptor-α, and retinoic acid receptor-β, four key transcription regulators of HSC adipogenic phenotype. Curcumin also reduced the expression of Frizzled and β-catenin, upregulated the expression of adipogenic transcription factors, and restored lipid content in HSCs. However, both WAY-262611 and LiCl abrogated curcumin restoration of lipogenesis and inhibition of fibrogenic marker expression in HSCs.

CONCLUSIONS

Wnt/β-catenin pathway was a profibrogenic signaling and inhibited lipogenesis by suppressing adipogenic transcription pattern in HSCs. Blockade of this pathway was associated with curcumin stimulation of HSC lipogenesis. We revealed a novel mechanism underlying curcumin restoration of lipid droplets during HSC activation.

Prostaglandin E2 promotes human cholangiocarcinoma cell proliferation, migration and invasion through the upregulation of β-catenin expression via EP3-4 receptor

Prostaglandin E2 (PGE2) is involved in cholangiocarcinoma cell proliferation, migration and invasion through E prostanoid receptors, including EP1, EP2 and EP4. However, the functions and the mechanisms of those splice variants of EP3 receptors in promoting liver cancer cell growth and invasion remain to be elucidated. In our previous studies, four isoforms of EP3 receptors, EP3-4, EP3-5, EP3-6 and EP3-7 receptors, were detected in CCLP1 and HuCCT1 cells. However, the functions of these receptors in these cells have yet to be determined. It was reported that β-catenin is closely correlated with malignancy, including cholangiocarcinoma. The present study was designed to examine the effects of 4-7 isoforms of EP3 in promoting cholangiocarcinoma progression and the mechanisms by which PGE2 increases β-catenin protein via EP3 receptors. The results showed that PGE2 promotes cholangiocarcinoma progression via the upregulation of β-catenin protein, and the EP3-4 receptor pathway is mainly responsible for this regulation. These findings reveal that PGE2 upregulated the cholangiocarcinoma cell β-catenin protein through the EP3-4R/Src/EGFR/PI3K/AKT/GSK-3β pathway. The present study identified the functions of EP3 and the mechanisms by which PGE2 regulates β-catenin expression and promoted cholangiocarcinoma cell growth and invasion.

β-Catenin Signaling and Roles in Liver Homeostasis, Injury, and Tumorigenesis

β-catenin (encoded by CTNNB1) is a subunit of the cell surface cadherin protein complex that acts as an intracellular signal transducer in the WNT signaling pathway; alterations in its activity have been associated with the development of hepatocellular carcinoma and other liver diseases. Other than WNT, additional signaling pathways also can converge at β-catenin. β-catenin also interacts with transcription factors such as T-cell factor, forkhead box protein O, and hypoxia inducible factor 1α to regulate the expression of target genes. We discuss the role of β-catenin in metabolic zonation of the adult liver. β-catenin also regulates the expression of genes that control metabolism of glucose, nutrients, and xenobiotics; alterations in its activity may contribute to the pathogenesis of nonalcoholic steatohepatitis. Alterations in β-catenin signaling may lead to activation of hepatic stellate cells, which is required for fibrosis. Many hepatic tumors such as hepatocellular adenomas, hepatocellular cancers, and hepatoblastomas have mutations in CTNNB1 that result in constitutive activation of β-catenin, so this molecule could be a therapeutic target. We discuss how alterations in β-catenin activity contribute to liver disease and how these might be used in diagnosis and prognosis, as well as in the development of therapeutics.

β-Catenin-Dependent Signaling Pathway Contributes to Renal Fibrosis in Hypertensive Rats

The mechanism of hypertension-induced renal fibrosis is not well understood, although it is established that high levels of angiotensin II contribute to the effect. Since β-catenin signal transduction participates in fibrotic processes, we evaluated the contribution of β-catenin-dependent signaling pathway in hypertension-induced renal fibrosis. Two-kidney one-clip (2K1C) hypertensive rats were treated with lisinopril (10 mg/kg/day for four weeks) or with pyrvinium pamoate (Wnt signaling inhibitor, single dose of 60 ug/kg, every 3 days for 2 weeks). The treatment with lisinopril reduced the systolic blood pressure from 220 ± 4 in 2K1C rats to 112 ± 5 mmHg (P < 0.05), whereas the reduction in blood pressure with pyrvinium pamoate was not significant (212 ± 6 in 2K1C rats to 170 ± 3 mmHg, P > 0.05). The levels of collagen types I and III, osteopontin, and fibronectin decreased in the unclipped kidney in both treatments compared with 2K1C rats. The expressions of β-catenin, p-Ser9-GSK-3beta, and the β-catenin target genes cyclin D1, c-myc, and bcl-2 significantly decreased in unclipped kidney in both treatments (P < 0.05). In this study we provided evidence that β-catenin-dependent signaling pathway participates in the renal fibrosis induced in 2K1C rats.

Musashi-2 promotes hepatitis Bvirus related hepatocellular carcinoma progression via the Wnt/β-catenin pathway

Our recent study observed that the expression of Musashi-2 (MSI2), a member of the Musashi family, was up-regulated in hepatitis B virus (HBV) related hepatocellular carcinoma parenchymal cells. Using quantitative PCR, tissue microarray (TMA) and immunohistochemical staining, we evaluated MSI2 mRNA and protein levels in tumor tissues from patients with different stages of hepatocellular carcinoma with paired adjacent noncancerous sample sets. The following techniques were used to further investigate MSI2 function and its potential molecular mechanism: RNAi, wound healing assay, Transwell assay, quantitative PCR and western blot analysis. Immunohistochemical detection of MSI2 on a TMA containing 106 paired specimens showed that increased cytoplasmic and nuclear MSI2 staining was significantly associated with tumor size, tumor differentiation, recurrence, TNM stage, vessel invasion and Ki-67 proliferative index. Patients with MSI2-positive tumors had a significantly higher disease recurrence rate and poorer survival than patients with MSI2-negative tumors after radical surgery. Based on univariate analysis, MSI2 expression showed an unfavorable influence on both disease-free survival and overall survival. Multivariate analysis revealed that higher MSI2 expression, together with tumor size, tumor differentiation, tumor thrombus, and Ki-67 expression were independent predictors of overall survival. With MSI2 knockdown, hepatoma cell migration and invasion were inhibited and the expression of β-catenin, T cell factor (TCF) and lymphoid enhancer factor (LEF) were dysregulated. Thus, we propose that MSI2 may predict unfavorable outcomes in hepatitis B virus related hepatocellular carcinoma and promote cancer progression via the Wnt/β-catenin signaling pathway.

DCDC2 mutations cause a renal-hepatic ciliopathy by disrupting Wnt signaling

Nephronophthisis-related ciliopathies (NPHP-RC) are recessive diseases characterized by renal dysplasia or degeneration. We here identify mutations of DCDC2 as causing a renal-hepatic ciliopathy. DCDC2 localizes to the ciliary axoneme and to mitotic spindle fibers in a cell-cycle-dependent manner. Knockdown of Dcdc2 in IMCD3 cells disrupts ciliogenesis, which is rescued by wild-type (WT) human DCDC2, but not by constructs that reflect human mutations. We show that DCDC2 interacts with DVL and DCDC2 overexpression inhibits β-catenin-dependent Wnt signaling in an effect additive to Wnt inhibitors. Mutations detected in human NPHP-RC lack these effects. A Wnt inhibitor likewise restores ciliogenesis in 3D IMCD3 cultures, emphasizing the importance of Wnt signaling for renal tubulogenesis. Knockdown of dcdc2 in zebrafish recapitulates NPHP-RC phenotypes, including renal cysts and hydrocephalus, which is rescued by a Wnt inhibitor and by WT, but not by mutant, DCDC2. We thus demonstrate a central role of Wnt signaling in the pathogenesis of NPHP-RC, suggesting an avenue for potential treatment of NPHP-RC.

Transfection with recombinant adenovirus vector expressing secreted frizzled related protein inhibits liver fibrosis in mice

AIM: To construct a recombinant adenovirus vector expressing secreted frizzled related protein (SFRP), and to assess the inhibitory effect of SFRP overexpression on experimental hepatic fibrosis (HF) in mice.

METHODS: Liposome-mediated transfection was used to introduce recombinant adenovirus pAd-Track-PPARγ2-CMV carrying the SFRP5 gene into liver cells from mice with CCl₄ induced HF to obtain recombinant adenovirus infected HF cells. Western blot, immunofluorescence microscopy and confocal laser microscopy were used to analyze the inhibitory effect of SFRP overexpression on experimental HF.

RESULTS: Cells infected with the recombinant adenovirus vector had higher expression of SFRP5 protein. Double immunofluorescence showed SFRP5 over expression inhibited the expression of α-smooth muscle actin (α-SMA) and fibroblast-specific protein-1 (FSP-1) in liver cells. Pathological examination revealed that SFRP5 over expression significantly reduced the occurrence of epithelial-mesenchymal transition (EMT) in liver cells (SFRP group vs control group, P < 0.05).

CONCLUSION: We have successfully constructed a recombinant adenovirus containing the SFRP5 gene, and it can effectively increase the expression of SFRP5 gene in mouse HF cells, thereby inhibiting the occurrence of EMT and HF.

Regulation of activation and proliferation of hepatic stellate cells through the Wnt signaling pathway: Implications for treatment of liver fibrosis

Liver fibrosis, a reversible pathological condition occurring after chronic liver injury, is closely associated with the activation and proliferation of hepatic stellate cells (HSCs). Several studies have demonstrated that the Wnt signaling pathway is involved in the activation of HSCs, and then contributes to the occurrence and development of liver fibrosis. Thus, the Wnt signaling pathway and HSCs are considered to be the valid targets for the treatment of liver fibrosis. In recent years, domestic and international scholars have carried on many studies on the regulation of the Wnt signaling pathway and HSCs, trying to find out effective antifibrotic therapies. A large number of studies have shown that regulating HSCs can play a positive role in the treatment of liver fibrosis through the Wnt signaling pathway. On the basis of the relationship among the Wnt signaling pathway, HSCs and liver fibrosis, this review mainly summarizes the latest progress in the study of strategies for regulating HSCs through the Wnt signaling pathway and discusses the implications for the treatment of liver fibrosis.