Insulin-like growth factor binding protein-related protein 1 (IGFBPrP1) contributes to liver inflammation and fibrosis via activation of the ERK1/2 pathway

Autophagy in erectile dysfunction: focusing on apoptosis and fibrosis

In most types of erectile dysfunction, particularly in advanced stages, typical pathological features observed are reduced parenchymal cells coupled with increased tissue fibrosis. However, the current treatment methods have shown limited success in reversing these pathologic changes. Recent research has revealed that changes in autophagy levels, along with alterations in apoptosis and fibrosis-related proteins, are linked to the progression of erectile dysfunction, suggesting a significant association. Autophagy, known to significantly affect cell fate and tissue fibrosis, is currently being explored as a potential treatment modality for erectile dysfunction. However, these present studies are still in their nascent stage, and there are limited experimental data available. This review analyzes erectile dysfunction from a pathological perspective. It provides an in-depth overview of how autophagy is involved in the apoptotic processes of smooth muscle and endothelial cells and its role in the fibrotic processes occurring in the cavernosum. This study aimed to develop a theoretical framework for the potential effectiveness of autophagy in preventing and treating erectile dysfunction, thus encouraging further investigation among researchers in this area.

Molecular pathogenesis of subretinal fibrosis in neovascular AMD focusing on epithelial-mesenchymal transformation of retinal pigment epithelium

Age-related macular degeneration (AMD) is a leading cause of vision loss among elderly people in developed countries. Neovascular AMD (nAMD) accounts for more than 90% of AMD-related vision loss. At present, intravitreal injection of anti-vascular endothelial growth factor (anti-VEGF) is widely used as the first-line therapy to decrease the choroidal and retinal neovascularizations, and thus to improve or maintain the visual acuity of the patients with nAMD. However, about 1/3 patients still progress to irreversible visual impairment due to subretinal fibrosis even with adequate anti-VEGF treatment. Extensive literatures support the critical role of epithelial-mesenchymal transformation (EMT) of retinal pigment epithelium (RPE) in the pathogenesis of subretinal fibrosis in nAMD, but the underlying mechanisms still remain largely unknown. This review summarized the molecular pathogenesis of subretinal fibrosis in nAMD, especially focusing on the transforming growth factor-β (TGF-β)-induced EMT pathways. It was also discussed how these pathways crosstalk and respond to signals from the microenvironment to mediate EMT and contribute to the progression of nAMD-related subretinal fibrosis. Targeting EMT signaling pathways might provide a promising and effective therapeutic strategy to treat subretinal fibrosis secondary to nAMD.

IGFBP7 remodels the tumor microenvironment of esophageal squamous cell carcinoma by activating the TGFβ1/SMAD signaling pathway

Esophageal squamous cell carcinoma (ESCC) is the most common type of esophageal cancer, and its development, growth, and invasiveness are regulated by the tumor microenvironment (TME). Insulin-like growth factor-binding protein-7 (IGFBP7), which is closely related to various tumors, transforming growth factor-β1 (TGFβ1), which is a key signal mediator in oncogenesis, α-smooth muscle actin (α-SMA), and collagen I are important components of the TME. IGFBP7 can upregulate the expression of TGFβ1 and activate the TGFβ1/SMAD signaling pathway, which leads to an increase in collagen I in hepatic stellate cells (HSCs). However, the contribution of IGFBP7 to TGFβ1 and the TME in the progression of ESCC remains unknown. In the present study, we investigated IGFBP7 expression and its effects on TGFβ1 and the TME in ESCC. A total of 45 patients were divided into three groups: early-tumor group (n=15), advanced-tumor group (n=15), and paracancer control group (n=15). The EC109 cell line was cultured and treated with AdIGFBP7 and LvshTGFβ1, and the expression levels of IGFBP7, TGFβ1, α-SMA, collagen I, and p-SMAD2/3 were determined by immunohistochemical staining and western blotting analysis. IGFBP7, TGFβ1, α-SMA, and collagen I were upregulated in the ESCC samples compared with the control samples (P<0.05), and the values peaked in the advanced-tumor group (P<0.05). Compared with the control group, the TGFβ1, α-SMA, p-SMAD2/3, and collagen I proteins were gradually increased from 24 to 72 h in the EC109 cells treated with AdIGFBP7 (P<0.05). Inhibition of TGFβ1 expression in the EC109 cells treated with AdIGFBP7 gradually reduced the expression of α-SMA, collagen I, and p-SMAD2/3 from 24 to 72 h (P<0.05). These findings suggest that increased IGFBP7 may accelerate the progression of ESCC by upregulating TGFβ1, α-SMA, and collagen I via activating the TGFβ1/SMAD signaling pathway, which could remodel the TME.

KLF7/VPS35 axis contributes to hepatocellular carcinoma progression through CCDC85C-activated β-catenin pathway

Objective

Dysregulation of KLF7 participates in the development of various cancers, but it is unclear whether there is a link between HCC and aberrant expression of KLF7. The aim of this study was to investigate the role of KLF7 in proliferation and migration of hepatocellular carcinoma (HCC) cells.

Methods

CCK8, colony growth, transwell, cell cycle analysis and apoptosis detection were performed to explore the effect of KLF7, VPS35 and Ccdc85c on cell function in vitro. Xenografted tumor growth was used to assess in vivo role of KLF7. Chip-qPCR and luciferase reporter assays were applied to check whether KLF7 regulated VPS35 at transcriptional manner. Co-IP assay was performed to detect the interaction between VPS35 and Ccdc85c. Immunohistochemical staining and qRT-PCR analysis were performed in human HCC sampels to study the clinical significance of KLF7, VPS35 and β-catenin.

Results

Firstly, KLF7 was highly expressed in human HCC samples and correlated with patients’ differentiation and metastasis status. KLF7 overexpression contributed to cell proliferation and invasion of HCC cells in vitro and in vivo. KLF7 transcriptional activation of VPS35 was necessary for HCC tumor growth and metastasis. Further, co-IP studies revealed that VPS35 could interact with Ccdc85c in HCC cells. Rescue assay confirmed that overexpression of VPS35 and knockdown of Ccdc85c abolished the VPS35-medicated promotion effect on cell proliferation and invasion. Finally, KLF7/VPS35 axis regulated Ccdc85c, which involved in activation of β-catenin signaling pathway, confirmed using β-catenin inhibitor, GK974. Functional studies suggested that downregulation of Ccdc85c partly reversed the capacity of cell proliferation and invasion in HCC cells, which was regulated by VPS35 upregulation. Lastly, there was a positive correlation among KLF7, VPS35 and active-β-catenin in human HCC patients.

Conclusion

We demonstrated that KLF7/VPS35 axis promoted HCC cell progression by activating Ccdc85c-medicated β-catenin pathway. Targeting this signal axis might be a potential treatment strategy for HCC.

Neferine Exerts Antioxidant and Anti-Inflammatory Effects on Carbon Tetrachloride-Induced Liver Fibrosis by Inhibiting the MAPK and NF-κB/IκBα Pathways

Reversible liver fibrosis is the consequence of diverse liver injuries. Oxidative stress combined with inflammation is the primary cause of carbon tetrachloride- (CCl₄-) induced liver fibrosis. Neferine is a bibenzyl isoquinoline alkaloid, which has strong anti-inflammatory and antioxidant properties. The present study attempted to find its antiliver fibrosis effect and explore the potential mechanism to relieve oxidative stress and inflammation in rats with CCl₄-induced liver fibrosis. Herein, we found that neferine noticeably mitigated fibrosis and improved liver function. Furthermore, neferine increased the activity of antioxidant enzymes, such as superoxide dismutase (SOD), glutathione peroxidase (GSH-PX), and catalase (CAT), but decreased the level of malondialdehyde (MDA). Neferine also decreased the levels of alpha-smooth muscle actin (α-SMA), transforming growth factor β1 (TGF-β1), and inflammatory factors. These results may demonstrate that neferine could effectively inhibit oxidative stress and inflammation in liver fibrosis. To account for the potential mechanism by which neferine relieves oxidative stress and inflammation in liver fibrosis rats, immunohistochemistry analyses and western blotting were performed. The results showed that neferine inhibited the mitogen-activated protein kinase (MAPK) pathway, as evidenced by the reduced phosphorylation of p38 MAPK, ERK 1/2, and JNK. And it inhibited the nuclear factor- (NF-) κB/IκBα pathway, as evidenced by preventing the translocation of NF-κB into nuclei. Our findings indicated a protective role for neferine, acting as an antioxidant and anti-inflammatory agent in CCl₄-induced liver fibrosis.

miR-16 integrates signal pathways in myofibroblasts: determinant of cell fate necessary for fibrosis resolution

Liver fibrosis is characterized by the transdifferentiation of hepatic stellate cells (HSCs) to myofibroblasts and poor response to treatment. This can be attributed to the myofibroblast-specific resistance to phenotype reversal. In this study, we complemented miR-16 into miR-16-deficient myofibroblasts and analyzed the global role of miR-16 using transcriptome profiling and generating a pathway-based action model underlying transcriptomic regulation. Phenotypic analysis of myofibroblasts and fibrogenic characterization were used to understand the effect of miR-16 on phenotypic remodeling of myofibroblasts. miR-16 expression altered the transcriptome of myofibroblasts to resemble that of HSCs. Simultaneous targeting of Smad2 and Wnt3a, etc. by miR-16 integrated signaling pathways of TGF-β and Wnt, etc., which underlay the comprehensive regulation of transcriptome. The synergistic effect of miR-16 on the signaling pathways abolished the phenotypic characteristics of myofibroblasts, including collagen production and inhibition of adipogenesis. In vivo, myofibroblast-specific expression of miR-16 not only eliminated mesenchymal cells with myofibroblast characteristics but also restored the phenotype of HSCs in perisinusoidal space. This phenotypic remodeling resolved liver fibrosis induced by chronic wound healing. Therefore, miR-16 may integrate signaling pathways crucial for the fate determination of myofibroblasts. Its global effect induces the reversal of HSC-to-myofibroblast transdifferentiation and, subsequently, the resolution of fibrogenesis. Taken together, these findings highlight the potential of miR-16 as a promising therapeutic target for liver fibrosis.

Self-eating: friend or foe? The emerging role of autophagy in fibrotic diseases

Fibrosis occurs in most human organs including the liver, lung, heart and kidney, and is crucial for the progression of most chronic diseases. As an indispensable catabolic process for intracellular quality control and homeostasis, autophagy occurs in most mammalian cells and is implicated in many biological processes including fibrogenesis. Although advances have been made in understanding autophagy process, the potential role of autophagy in fibrotic diseases remains controversial and has recently attracted a great deal of attention. In the current review, we summarize the commonalities of autophagy affecting different types of fibrosis in different organs, including the liver, lung, heart, and kidney as well as in cystic fibrosis, systematically outline the contradictory results and highlight the distinct role of autophagy during the various stages of fibrosis. In summary, the exact role autophagy plays in fibrogenesis depends on specific cell types and different stimuli, and identifying and evaluating the pathogenic contribution of autophagy in fibrogenesis will promote the discovery of novel therapeutic strategies for the clinical management of these fibrotic diseases.

Insulin-Like Growth Factor Binding Protein-Related Protein 1 Activates Primary Hepatic Stellate Cells via Autophagy Regulated by the PI3K/Akt/mTOR Signaling Pathway

BACKGROUND

Autophagy is a self-degrading process. Previously, we showed that insulin-like growth factor binding protein-related protein 1 (IGFBPrP1) is a novel transforming growth factor β1 (TGFβ1)-interacting factor in liver fibrosis; the role of TGFβ1-mediated autophagy in hepatic stellate cells (HSCs) activation has been investigated. However, whether autophagy is regulated by IGFBPrP1 remains unknown.

AIMS

We investigated the interactions among IGFBPrP1, autophagy, and activation of primary rat HSCs.

METHODS

Primary HSCs were separated from Sprague Dawley rats by two-step enzymatic digestion, and then, we overexpressed or inhibited IGFBPrP1 expression in HSCs under serum-starved condition. Autophagy inducer rapamycin or inhibitor 3-methyladenine (3MA) was used to assess the relationship between autophagy and HSCs activation.

RESULTS

We observed the expression of activation marker α-SMA and autophagy markers such as LC3B and Beclin1, which were significantly increased in HSCs treated with adenovirus vector harboring the IGFBPrP1 gene (AdIGFBPrP1) compared to cells cultured under serum-starved. In comparison, HSCs treated with shIGFBPrP1 showed opposite results. Furthermore, HSCs activation and autophagy increased when cells were treated with rapamycin, whereas opposite results were obtained when cells were treated with 3MA. AdIGFBPrP1 treatment downregulated the phosphorylation of Akt and mTOR.

CONCLUSION

Autophagy was induced in IGFBPrP1-treated primary HSCs, and IGFBPrP1-induced autophagy promoted the activation of HSCs and extracellular matrix expression, the underlying mechanism of which may involve the phosphatidylinositide 3-kinase/Akt/mTOR signaling pathway.

Production of insulin-like growth factor-binding proteins during the development of hepatic fibrosis due to chronic hepatitis C

INTRODUCTION AND AIMS

Insulin-like growth factor 1 is modulated by the insulin-like growth factor-binding proteins (IGFBPs) that are synthesized in the liver. The aim of the present study was to evaluate the concentrations of IGFBPs 1-7 in patients with chronic hepatitis C and study their association with fibrosis stage.

PATIENTS AND METHODS

A prospective, cross-sectional study was conducted that included patients with chronic hepatitis C. The stages of fibrosis were determined through FibroTest and FibroScan and the patients were compared with a control group. Serum levels of IGFBPs 1-7 were quantified through multiple suspension arrays. The Kruskal-Wallis test, Mann-Whitney U test, Spearman's correlation, and ROC curves were used for the statistical analysis.

RESULTS

Upon comparing the patients and controls, the highest concentrations were found in IGFBPs 1, 2, 4, and 7 (p=0.02, p=0.002, p=0.008, and p<0.001, respectively). IGFBP-3 levels had a tendency to be lower in the patients (p=0.066), whereas values were similar between patients and controls for IGFBP-5 and 6 (p=0.786 and p=0.244, respectively). Of the seven IGFBPs, IGFBP-3 concentrations were the highest. There were significant differences between fibrosis stages for IGFBP-5 and IGFBP-7.

CONCLUSION

IGFBPs play a relevant role in the fibrotic process in liver damage. IGFBP-7, in particular, differentiates fibrosis stages, making it a potential serum biomarker.

The lncRNA NEAT1/miR-29b/Atg9a axis regulates IGFBPrP1-induced autophagy and activation of mouse hepatic stellate cells

AIMS

Insulin-like growth factor binding protein-related protein 1 (IGFBPrP1) promotes hepatic stellate cell (HSC) autophagy and activation. However, the underlying mechanism remains unknown. Noncoding RNAs (ncRNAs) including long noncoding RNAs (lncRNAs) and microRNAs (miRNAs), have received increasing attention. We aimed to investigate the roles of the lncRNA nuclear enriched abundant transcript 1 (NEAT1), miR-29b, and autophagy related protein 9a (Atg9a), and their relationships with each other during IGFBPrP1-induced HSC autophagy and activation.

MAIN METHODS

Levels of NEAT1, miR-29b, Atg9a, and autophagy were detected in adenovirus-mediated IGFBPrP1 (AdIGFBPrP1)-treated mouse liver tissue and immortalized mouse hepatic stellate cell line JS1 transfected with either AdIGFBPrP1 or siIGFBPrP1. In AdIGFBPrP1-treated JS1 cells, autophagy and activation were detected after altering NEAT1, miR-29b, or Atg9a levels. In AdIGFBPrP1-treated JS1 cells, relationships among NEAT1, miR-29b, and Atg9a were explored using dual-luciferase reporter assays, Western blot, qRT-PCR, and immunofluorescence.

KEY FINDINGS

IGFBPrP1 increased levels of NEAT1, Atg9a, and autophagy while decreasing the level of miR-29b in mouse liver tissues and mouse HSCs. Moreover, NEAT1 increased HSC autophagy and activation while miR-29b decreased both processes. Atg9a also participated in IGFBPrP1-induced HSC autophagy and activation. Importantly, NEAT1, miR-29b, and Atg9a formed a NEAT1/miR-29b/Atg9a regulatory axis for IGFBPrP1-induced HSC autophagy and activation.

SIGNIFICANCE

Our study unveiled the new NEAT1/miR-29b/Atg9a regulatory axis involved in IGFBPrP1-induced mouse HSC autophagy and activation. The study thus provides new insights in the pathogenesis and potential therapeutic strategies of liver fibrosis.

IGFBPrP1 accelerates autophagy and activation of hepatic stellate cells via mutual regulation between H19 and PI3K/AKT/mTOR pathway

BACKGROUND

Our previous study found that insulin-like growth factor binding protein-associated protein (IGFBPrP1) drives hepatic stellate cells (HSCs) activation, and IGFBPrP1 and transforming growth factor β1 (TGFβ1) likely interact with each other to promote HSCs activation. TGFβ1 reportedly promotes autophagy and contributes to HSCs activation; however, the mechanism between IGFBPrP1 and autophagy in liver fibrogenesis is yet unknown. Moreover, long noncoding RNA (lncRNA) H19 participates in autophagy regulation and plays a crucial function in liver fibrosis.

AIMS

To define the relationship between IGFBPrP1 and autophagy and the role of H19 in IGFBPrP1-induced hepatic fibrosis.

METHODS

IGFBPrP1 and autophagy were detected in bile duct ligation (BDL)-induced hepatic fibrosis. Adenovirus-mediated IGFBPrP1 was transfected into mouse liver and JS-1 cells with or without LY294002 or rapamycin to examine the effects of IGFBPrP1 on HSCs activation and autophagy as well as the PI3K/AKT/mTOR pathway. lncRNA H19 in liver fibrosis tissues and JS-1 cells induced by IGFBPrP1 were detected, then autophagy and HSCs activation level were detected in JS-1 cells by IGFBPrP1 with H19 overexpression or knowdown.

RESULTS

IGFBPrP1 expression and autophagy level were concomitantly increased in liver tissue with BDL-induced hepatic fibrosis. Furthermore, we found that IGFBPrP1 stimulated autophagy and HSCs activation in vivo and in vitro, and PI3K/AKT/mTOR signaling pathway was involved in the regulation of autophagy by IGFBPrP1. In addition, H19 promoted autophagy by interacting with the PI3K/AKT/mTOR pathway in IGFBPrP1-induced HSCs activation.

CONCLUSIONS

IGFBPrP1 promoted autophagy and contributed to HSCs activation via mutual regulation between H19 and the PI3K/AKT/mTOR pathway.

Puerarin alleviates liver fibrosis via inhibition of the ERK1/2 signaling pathway in thioacetamide-induced hepatic fibrosis in rats

Liver fibrosis is a complex pathological process and an early step in the progression of liver cirrhosis, which can eventually develop into hepatocellular carcinoma. Currently, there is no effective treatment for liver fibrosis. Puerarin is a traditional Chinese herb, which is commonly used in the treatment of various diseases. In addition, it is also believed to have a therapeutic effect in liver fibrosis. However, whether puerarin reduces liver fibrosis via the ERK1/2 signaling pathway to inhibit the activation of hepatic stellate cell (HSC) and excessive collagen deposition in liver fibrosis remains unknown. The aim of the current study was to establish a liver fibrosis in vivo model by intraperitoneal injection of thioacetamide (TAA) and investigate the effect of puerarin in the treatment of liver fibrosis. Hematoxylin and eosin and Van Gieson's staining were used to examine histopathological changes associated with liver fibrosis. Liver hydroxyproline content was examined to determine the total amount of collagen in the liver. The relative protein expression levels of transforming growth factor β1 (TGFβ1), α-smooth muscle actin (α-SMA), collagen type I, fibronectin, ERK1/2 and p-ERK1/2 were determined by western blot analysis. In the TAA group, histopathological changes and collagen fiber content in rat liver tissue samples were significantly increased compared with the control group (P<0.05). In addition, treatment with puerarin significantly decreased histopathological changes and collagen fiber content in rat liver tissue samples (P<0.05). The relative protein expression levels of TGFβ1, α-SMA, collagen type I, fibronectin and p-ERK1/2 were significantly upregulated in the TAA group compared with the control group (P<0.05), whereas puerarin treatment reversed these changes. These findings suggest that treatment with puerarin may reduce HSC activation and alleviate extracellular matrix protein expression levels by inhibiting the TGF-β/ERK1/2 pathway in liver fibrosis.

Insulin-like growth factor binding protein related protein 1 knockdown attenuates hepatic fibrosis via the regulation of MMPs/TIMPs in mice

BACKGROUND

Previous research suggested that insulin-like growth factor binding protein related protein 1 (IGFBPrP1), as a novel mediator, contributes to hepatic fibrogenesis. Matrix metalloproteinases (MMP) and tissue inhibitors of metalloproteinases (TIMP) play an essential role in hepatic fibrogenesis by regulating homeostasis and remodeling of the extracellular matrix (ECM). However, the interaction between IGFBPrP1 and MMP/TIMP is not clear. The present study was to knockdown IGFBPrP1 to investigate the correlation between IGFBPrP1 and MMP/TIMP in hepatic fibrosis.

METHODS

Hepatic fibrosis was induced by thioacetamide (TAA) in mice. Knockdown of IGFBPrP1 expression by ultrasound-targeted microbubble destruction-mediated CMB-shRNA-IGFBPrP1 delivery, or inhibition of the Hedgehog (Hh) pathway by cyclopamine treatment, was performed in TAA-induced liver fibrosis mice. Hepatic fibrosis was determined by hematoxylin and eosin and Sirius red staining. Hepatic expression of IGFBPrP1, α-smooth muscle actin (α-SMA), transforming growth factor β 1 (TGFβ1), collagen I, MMPs/TIMPs, Sonic Hedgehog (Shh), and glioblastoma family transcription factors (Gli1) were investigated by immunohistochemical staining and Western blotting analysis.

RESULTS

We found that hepatic expression of IGFBPrP1, TGFβ1, α-SMA, and collagen I were increased longitudinally in mice with TAA-induced hepatic fibrosis, concomitant with MMP2/TIMP2 and MMP9/TIMP1 imbalance and Hh pathway activation. Knockdown of IGFBPrP1 expression, or inhibition of the Hh pathway, reduced the hepatic expression of IGFBPrP1, TGFβ1, α-SMA, and collagen I and re-established MMP2/TIMP2 and MMP9/TIMP1 balance.

CONCLUSIONS

Our findings suggest that IGFBPrP1 knockdown attenuates liver fibrosis by re-establishing MMP2/TIMP2 and MMP9/TIMP1 balance, concomitant with the inhibition of hepatic stellate cell activation, down-regulation of TGFβ1 expression, and degradation of the ECM. Furthermore, the Hh pathway mediates IGFBPrP1 knockdown-induced attenuation of hepatic fibrosis through the regulation of MMPs/TIMPs balance.

Antifibrotic effects of Fraxetin on carbon tetrachloride-induced liver fibrosis by targeting NF-κB/IκBα, MAPKs and Bcl-2/Bax pathways

BACKGROUND

Liver fibrosis is a chronic lesion which ultimately results in cirrhosis and possible death. Although the high incidence and lethality, few therapies are effective for liver fibrosis. Fraxetin (7,8-dihydroxy-6-methoxy coumarin), a natural product extracted from cortex fraxini, has exhibited a significant hepatoprotective and anti-fibrotic properties. However, the underlying mechanism of the anti-hepatic fibrotic property remains unknown.

METHODS

48 Male Sprague Dawley rats were divided into four groups at random which were named as normal group, model group, fraxetin 25 mg/kg and 50 mg/kg group. The experimental model of liver fibrosis was founded by carbon tetrachloride (CCl₄) rats which were simultaneously treated with fraxetin (25 mg/kg or 50 mg/kg). Normal groups received equal volumes of saline and peanut oil.

RESULTS

Results showed that fraxetin ameliorated CCl₄ induced liver damage and fibrosis. Furthermore, histopathology examinations revealed that fraxetin improved the morphology and alleviated collagen deposition in fibrotic liver. Fraxetin inhibited inflammation and hepatocytes apoptosis by modulating the NF-κB/IκBα, MAPKs and Bcl-2/Bax signaling pathways.

CONCLUSION

Our findings indicate that fraxetin is effective in preventing liver fibrosis through inhibiting inflammation and hepatocytes apoptosis which is associated with regulating NF-κB/IκBα, MAPKs and Bcl-2/Bax signaling pathways in rats.

Interaction between insulin-like growth factor binding protein-related protein 1 and transforming growth factor beta 1 in primary hepatic stellate cells

BACKGROUND

We previously showed that insulin-like growth factor binding protein-related protein 1 (IGFBPrP1) is a novel mediator in liver fibrosis. Transforming growth factor beta 1 (TGFβ1) is known as the strongest effector of liver fibrosis. Therefore, we aimed to investigate the detailed interaction between IGFBPrP1 and TGFβ1 in primary hepatic stellate cells (HSCs).

METHODS

We overexpressed TGFβ1 or IGFBPrP1 and inhibited TGFβ1 expression in primary HSCs for 6, 12, 24, 48, 72, and 96 hours to investigate their interaction and observe the accompanying expressions of α-smooth muscle actin (α-SMA), collagen I, fibronectin, and phosphorylated-mothers against decapentaplegic homolog 2/3 (p-Smad2/3).

RESULTS

We found that the adenovirus vector encoding the TGFβ1 gene (AdTGFβ1) induced IGFBPrP1 expression while that of α-SMA, collagen I, fibronectin, and TGFβ1 increased gradually. Concomitantly, AdIGFBPrP1 upregulated TGFβ1, α-SMA, collagen I, fibronectin, and p-Smad2/3 in a time-dependent manner while IGFBPrP1 expression was decreased at 96 hours. Inhibition of TGFβ1 expression reduced the IGFBPrP1-stimulated expression of α-SMA, collagen I, fibronectin, and p-Smad2/3.

CONCLUSIONS

These findings for the first time suggest the existence of a possible mutually regulation between IGFBPrP1 and TGFβ1, which likely accelerates liver fibrosis progression. Furthermore, IGFBPrP1 likely participates in liver fibrosis in a TGFβ1-depedent manner, and may act as an upstream regulatory factor of TGFβ1 in the Smad pathway.

Screening for and validation of a hepatic fibrosis-related pathway induced by insulin-like growth factor-binding protein-related protein 1

OBJECTIVE

Our previous studies characterized insulin-like growth factor-binding protein-related protein 1 (IGFBPrP1) as a molecule that promotes hepatic fibrogenesis, but its mechanism has not been fully elucidated. Here, we have investigated the effect of IGFBPrP1 on gene expression in the hepatic fibrosis-related pathway.

MATERIALS AND METHODS

Sprague-Dawley rats received injections of an adenovirus carrying IGFBPrP1 or EGFP cDNA into their tail veins. In hepatic preparations, hepatic stellate cell activation was determined by α-smooth muscle actin expression and hepatic fibrosis by Sirius red staining and hydroxyproline content analysis. IGFBPrP1-inducible genes of the hepatic fibrosis-related pathway were assessed by PCR array. Expression of IGFBPrP1 and transforming growth factor β1 (TGFβ1) and array results were evaluated by quantitative real-time PCR and western blotting.

RESULTS

IGFBPrP1-overexpressing rats showed an increase in α-smooth muscle actin expression and collagen and hydroxyproline content in the liver. The PCR array results indicated that some genes were upregulated and some were downregulated in Ad-IGFBPrP1-infected rats. Among these, Egr1, MAP2K2 (MEK2) and MAPK3 (ERK1) expression increased, whereas PTEN and Hhip mRNA expression decreased. Egr1 protein levels increased and peaked 2 weeks after infection and then decreased gradually. PTEN protein decreased gradually in Ad-IGFBPrP1-infected rats with a concurrent increase in the degree of hepatic fibrosis. TGFβ1 levels increased during hepatic fibrosis development in liver tissues.

CONCLUSION

Egr1, PTEN, Hhip, MAP2K2 (MEK2) and MAPK3 (ERK1) were identified as candidate genes of the IGFBPrP1-induced hepatic fibrosis-related pathway. IGFBPrP1 promoted hepatic fibrosis mainly by enhancing the TGFβ1 expression that it triggered.