Notch signaling and new therapeutic options in liver disease

3D organoid cultivation improves the maturation and functional differentiation of cholangiocytes from human pluripotent stem cells

Idiopathic cholangiopathies are diseases that affect cholangiocytes, and they have unknown etiologies. Currently, orthotopic liver transplantation is the only treatment available for end-stage liver disease. Limited access to the bile duct makes it difficult to model cholangiocyte diseases. In this study, by mimicking the embryonic development of cholangiocytes and using a robust, feeder- and serum-free protocol, we first demonstrate the generation of unique functional 3D organoids consisting of small and large cholangiocytes derived from human pluripotent stem cells (PSCs), as opposed to traditional 2D culture systems. At day 28 of differentiation, the human PSC-derived cholangiocytes expressed markers of mature cholangiocytes, such as CK7, CK19, and cystic fibrosis transmembrane conductance regulator (CFTR). Compared with the 2D culture system-generated cholangiocytes, the 3D cholangiocyte organoids (COs) showed higher expression of the region-specific markers of intrahepatic cholangiocytes YAP1 and JAG1 and extrahepatic cholangiocytes AQP1 and MUC1. Furthermore, the COs had small-large tube-like structures and functional assays revealed that they exhibited characteristics of mature cholangiocytes, such as multidrug resistance protein 1 transporter function and CFTR channel activity. In addition to the extracellular matrix supports, the epidermal growth factor receptor (EGFR)-mediated signaling regulation might be involved in this cholangiocyte maturation and differentiation. These results indicated the successful generation of intrahepatic and extrahepatic cholangiocytes by using our 3D organoid protocol. The results highlight the advantages of our 3D culture system over the 2D culture system in promoting the functional differentiation and maturation of cholangiocytes. In summary, in advance of the previous works, our study provides a possible concept of small-large cholangiocyte transdifferentiation of human PSCs under cost-effective 3D culture conditions. The study findings have implications for the development of effective cell-based therapy using COs for patients with cholangiopathies.

Notch Signaling: An Emerging Paradigm in the Pathogenesis of Reproductive Disorders and Diverse Pathological Conditions

The highly conserved Notch pathway, a pillar of juxtacrine signaling, orchestrates intricate intercellular communication, governing diverse developmental and homeostatic processes through a tightly regulated cascade of proteolytic cleavages. This pathway, culminating in the migration of the Notch intracellular domain (NICD) to the nucleus and the subsequent activation of downstream target genes, exerts a profound influence on a plethora of molecular processes, including cell cycle progression, lineage specification, cell-cell adhesion, and fate determination. Accumulating evidence underscores the pivotal role of Notch dysregulation, encompassing both gain and loss-of-function mutations, in the pathogenesis of numerous human diseases. This review delves deep into the multifaceted roles of Notch signaling in cellular dynamics, encompassing proliferation, differentiation, polarity maintenance, epithelial-mesenchymal transition (EMT), tissue regeneration/remodeling, and its intricate interplay with other signaling pathways. We then focus on the emerging landscape of Notch aberrations in gynecological pathologies predisposing individuals to infertility. By highlighting the exquisite conservation of Notch signaling in Drosophila and its power as a model organism, we pave the way for further dissection of disease mechanisms and potential therapeutic interventions through targeted modulation of this master regulatory pathway.

Leveraging stem cells to combat hepatitis: a comprehensive review of recent studies

Hepatitis is a significant global public health concern, with viral infections being the most common cause of liver inflammation. Antiviral medications are the primary treatments used to suppress the virus and prevent liver damage. However, the high cost of these drugs and the lack of awareness and stigma surrounding the disease create challenges in managing hepatitis. Stem cell therapy has arisen as a promising therapeutic strategy for hepatitis by virtue of its regenerative and immunomodulatory characteristics. Stem cells have the exceptional capacity to develop into numerous cell types and facilitate tissue regeneration, rendering them a highly promising therapeutic avenue for hepatitis. In animal models, stem cell therapy has demonstrated worthy results by reducing liver inflammation and improving liver function. Furthermore, clinical trials have been undertaken to assess the safety and effectiveness of stem cell therapy in individuals with hepatitis. This review aims to explore the involvement of stem cells in treating hepatitis and highlight the findings from studies conducted on both animals and humans. The objective of this review is to primarily concentrate on the ongoing and future clinical trials that assess the application of stem cell therapy in the context of hepatitis, including the transplantation of autologous bone marrow-derived stem cells, human induced pluripotent stem cells, and other mesenchymal stem cells. In addition, this review will explore the potential merits and constraints linked to stem cell therapy for hepatitis, as well as its prospective implications in the management of this disease.

Functional Enrichment Analysis of Tumor Microenvironment-Driven Molecular Alterations That Facilitate Epithelial-to-Mesenchymal Transition and Distant Metastasis

Nowadays, hepatocellular carcinoma (HCC) is the second leading cause of cancer deaths, and identifying the effective factors in causing this disease can play an important role in its prevention and treatment. Tumors provide effective agents for invasion and metastasis to other organs by establishing appropriate communication between cancer cells and the microenvironment. Epithelial-to-mesenchymal transition (EMT) can be mentioned as one of the effective phenomena in tumor invasion and metastasis. Several factors are involved in inducing this phenomenon in the tumor microenvironment, which helps the tumor survive and migrate to other places. It can be effective to identify these factors in the use of appropriate treatment strategies and greater patient survival. This study investigated the molecular differences between tumor border cells and tumor core cells or internal tumor cells in HCC for specific EMT genes. Expression of NOTCH1, ID1, and LST1 genes showed a significant increase at the HCC tumor border. Targeting these genes can be considered as a useful therapeutic strategy to prevent distant metastasis in HCC patients.

Signaling pathways of liver regeneration: Biological mechanisms and implications

The liver possesses a unique regenerative ability to restore its original mass, in this regard, partial hepatectomy (PHx) and partial liver transplantation (PLTx) can be executed smoothly and safely, which has important implications for the treatment of liver disease. Liver regeneration (LR) can be the very complicated procedure that involves multiple cytokines and transcription factors that interact with each other to activate different signaling pathways. Activation of these pathways can drive the LR process, which can be divided into three stages, namely, the initiation, progression, and termination stages. Therefore, it is important to investigate the pathways involved in LR to elucidate the mechanism of LR. This study reviews the latest research on the key signaling pathways in the different stages of LR.

Di-(2-ethylhexyl) phthalate (DEHP) promoted hepatic lipid accumulation by activating Notch signaling pathway

Di-(2-ethylhexyl) phthalate (DEHP) and mono-2-ethylhexyl phthalate (MEHP) can induce hepatic lipid metabolism disorders, while the molecular mechanism still remain unknown. We aim to explore the underlying mechanism of Notch signaling pathway on hepatic lipid accumulation induced by DEHP/MEHP. A total of 40 male wistar rats were exposed to DEHP (0, 5, 50, and 500 mg/kg/d) for 8 weeks, BRL-3A hepatocytes were exposed to MEHP (0, 10, 50, 100, and 200 μM) for 24 h. About 50 μM DAPT and 100 μg/mL Aspirin were used to inhibit Notch pathway and prevent inflammation, respectively. Real-Time PCR was performed to detect the mRNA expression, western blot and immunofluorescence were used to detect the protein expression. Lipids and inflammatory factors levels were determined by commercial kits. The results showed that DEHP/MEHP promoted the expression of Notch pathway molecules and lipids accumulation in rat livers/BRL-3A cells. The up-regulated Notch receptors were correlated with the TG levels in the rat liver. MEHP increased the levels of IL-8 and IL-1β. The lipids levels were reduced after anti-inflammation. The inhibition of Notch pathway reversed the elevation of inflammation and lipid accumulation caused by MEHP. In conclusion, this study demonstrated that DEHP/MEHP led to lipid accumulation in hepatocytes by up-regulating Notch pathway and the inflammation might play a key role in the process.

DLL4-Notch signalling in acute-on-chronic liver failure: State of the art and perspectives

Acute-on-chronic liver failure (ACLF) is a syndrome characterized by acute decompensation of chronic liver disease associated with multiple-organ failures and high short-term mortality. Acute insults to patients with chronic liver disease can lead to ACLF, among which, hepatitis B virus-related ACLF is the most common type of liver failure in the Asia-Pacific region. Currently, immune-metabolism disorders and systemic inflammation are proposed to be the main mechanisms of ACLF. The resulting cholestasis and intrahepatic microcirculatory dysfunction accelerate the development of ACLF. Treatments targeting immune regulation, metabolic balance, microcirculation maintenance and bile duct repair can alleviate inflammation and restore the tissue structure. An increasing number of studies have demonstrated that delta-like ligand 4 (DLL4), one of the Notch signalling ligands, plays a vital role in immune regulation, metabolism, angiogenesis, and biliary regeneration, which participate in liver pathological and physiological processes. The detailed mechanism of the DLL4-Notch signalling pathway in ACLF has rarely been investigated. Here, we review the evidence showing that DLL4-Notch signalling is involved in ACLF and analyse the potential role of DLL4 in the treatment of ACLF.

Effect of SNHG11/miR-7-5p/PLCB1 Axis on Acute Pancreatitis through Inhibiting p38MAPK Pathway

Acute pancreatitis (AP) is an inflammatory disease of the pancreas. A growing number of studies have shown that long noncoding RNAs (lncRNAs) play an important role in AP progression. Here, we aimed to elucidate the role of Small Nucleolar RNA Host Gene 11(SNHG11) and its underlying molecular mechanisms behind AP progression. The in vivo and in vitro AP cell models were established by retrograde injection of sodium taurocholate and caerulein stimulation into AR42J cells and HPDE6-C7 cells, respectively. A bioinformatics website predicted the relationship between SNHG11, miR-7-5p, and Phospholipase C Beta 1(PLCB1) and validated it with a dual-luciferase reporter assay and an RNA immunoprecipitation (RIP) assay. AR42J cells and HPDE6-C7 cells were transfected with an overexpression of plasmids or shRNA to investigate the effects of the SNHG11/miR-7-5p/PLCB1 axis on cell proliferation and apoptosis, inflammatory cytokine secretion, and acute pancreatitis. Low expression of SNHG11 and PLCB1 and high expression of miR-7-5p were observed in AP pancreatic tissue and AP cell models. SNHG11 overexpression inhibited apoptosis and inflammatory responses induced by caerulein. Simultaneously, we discovered that SNHG11 regulates PLCB1 expression by sponging miR-7-5p. PLCB1 overexpression abrogated inflammatory damage exacerbated by miR-7-5p enrichment. In addition, the SNHG11/miR-7-5p/PLCB1 axis could be involved in caerulein-induced inflammatory injury by participating in the p38MAPK signaling pathway. The overexpressed SNHG11/miR-7-5p/PLCB1 axis can inhibit AP progression by participating in the p38MAPK signaling pathway, thereby providing a potential therapeutic target and therapeutic direction for AP therapy.

miR-515-3p, miR-623, miR-1272 and Notch3 protein as new biomarkers of Hepatocellular carcinoma

BACKGROUNDS

Hepatocellular carcinoma (HCC) is a diversity of hepatocellular neoplasms and is more prevalence in people with chronic liver disease and cirrhosis. It has been revealed that modification in miRNA regulation possibly will be elaborated in HCC pathogenesis.

MATERIALS AND METHODS

In this research 40 samples of HCC subjects and 40 samples of healthy liver were considered. Total RNA was obtained from paraffin-embedded tissue blocks and miR-515, miR-623 and miR-1272 gene expression levels were quantified by Real-Time Quantitative Reverse Transcription PCR. Likewise, the Notch protein quantity was assayed in ffpe materials by immunohistochemistry.

RESULTS

Our study disclosed that Notch protein deals was ominously elevated in cancer cells than healthy cells (p<0.05). Data analysis also displayed that miR-515, miR-623 and miR-1272 expression levels were 3.8, 4.7, and 2.9 fold in normal tissues, respectively (p<0.05). Furthermore, it was found that expression levels of these genes are not dependent by hepatitis B and hepatic cirrhosis and it could be used as a marker of high specificity and sensitivity for the diagnosis of HCC.

DISCUSSIONS

Our study demonstrated main role of miR-515, miR-623 and miR-1272 in HCC pathogenesis and similarly disclosed that these genes expression could be utilized in HCC prognosis.

A PLCB1-PI3K-AKT Signaling Axis Activates EMT to Promote Cholangiocarcinoma Progression

As a member of the phospholipase family, phospholipase C beta 1 (PLCB1) is involved in phospholipid hydrolysis and is frequently upregulated in human cancer. However, little is known about the role of PLCB1 in cholangiocarcinoma (CCA). In this study, we uncover a role for PLCB1 in CCA progression and identify the underlying mechanisms. Both human CCA tissues and CCA cell lines expressed high levels of PLCB1. PLCB1 promoted tumor development and growth in various CCA mouse models, including transposon-based tumorigenesis models. PLCB1 activated PI3K/AKT signaling to induce CCA cells to undergo epithelial-to-mesenchymal transition (EMT). Mechanistically, PABPC1 interacted with PLCB1 and PI3K to amplify PLCB1-mediated EMT via PI3K/AKT/GSK3β/Snail signaling. Ectopic PLCB1 induced resistance to treatment with gemcitabine combined with cisplatin, which could be reversed by the AKT inhibitor MK2206. PLCB1 expression was regulated by miR-26b-5p through direct interaction with PLCB1 3'UTR. Collectively, these data identify a PLCB1-PI3K-AKT signaling axis vital for CCA development and EMT, suggesting that AKT can be used as a therapeutic target to overcome chemotherapy resistance in CCA patients with high PLCB1 expression. SIGNIFICANCE: PLCB1 functions as an oncogenic driver in cholangiocarcinoma development that confers an actionable therapeutic vulnerability to AKT inhibition.

A narrative review of liver regeneration-from models to molecular basis

Objective

To elucidate the characteristics of different liver regeneration animal models, understand the activation signals and mechanisms related to liver regeneration, and obtain a more comprehensive conception of the entire liver regeneration process.

Background

Liver regeneration is one of the most enigmatic and fascinating phenomena of the human organism. Despite suffering significant injuries, the liver still can continue to perform its complex functions through the regeneration system. Although advanced topics on liver regeneration have been proposed; unfortunately, complete regeneration of the liver has not been achieved until now. Therefore, increasing understanding of the liver regenerative process can help improve our treatment of liver failure. It will provide a new sight for the treatment of patients with liver injury in the clinic.

Methods

Literatures on liver regeneration animal models and involved basic research on molecular mechanisms were retrieved to analyze the characteristics of different models and those related to molecular basis.

Conclusions

The process of liver regeneration is complex and intricate, consisting of various and interactive pathways. There is sufficient evidence to demonstrate that liver regeneration is similar between humans and rodents. At the same time, many of the same cytokines, growth factors, and signaling pathways are relevant. There are many gaps in our current knowledge. Understanding of this knowledge will provide more supportive clinical treatment strategies, including small-scale liver transplantation and high-quality regenerative process after surgical resection, and offer possible targets to treat the dysregulation of regeneration that occurs in chronic hepatic diseases and tumors. Current research work, such as the use of animal models as in vivo vectors for high-quality human hepatocytes, represents a unique and significant cutting edge in the field of liver regeneration.

The Notch signaling pathway regulates macrophage polarization in liver diseases

The liver is not only the main metabolic site of exogenous compounds and drugs, but also an important immune organ in the human body. When a large number of nonself substances (such as drugs, alcohol, pathogens, microorganisms and their metabolites) enter the liver, they will cause serious liver diseases, including liver fibrosis, liver cirrhosis, liver failure, and hepatocellular carcinoma (HCC). Macrophages are the first line of defense against the invasion of exogenous pathogens and significant cellular components of the innate immune system. Macrophages have strong heterogeneity and plasticity. When different pathogens invade the body, they cause different types of polarization of macrophages through different molecular mechanisms. Notch signaling is considered to be the key regulator of the biological function of macrophages. Activating Notch signaling can regulate the differentiation of macrophages into M1 and play a role in promoting inflammation and antitumor activity, while blocking Notch signaling can polarize macrophages to M2, suppressing inflammation and promoting tumor growth. However, there are few studies on regulation of macrophage polarization by the Notch signaling pathway in liver diseases. Therefore, in this review, we will introduce the role of the Notch signaling pathway in regulating macrophage polarization in liver diseases.

Expression of Notch-Hif-1α signaling pathway in liver regeneration of rats

Objective

To investigate whether the Notch–Hif-1α signaling pathway is involved in liver regeneration.

Methods

Rats were divided into two groups and treated with daily intraperitoneal injections of saline (control) or the gamma-secretase inhibitor, Fli-06, for 2 days. Two-thirds of the rat livers were resected and rats were later euthanized at specific time points post-resection to analyze the remnant livers. Each group's liver/body weight ratio was calculated, and immunostaining and western blotting were used to determine the cell proliferation marker, PCNA and Ki-67 expression. Real-time PCR and western blotting were used to compare the mRNA expression of Notch homolog-1 (Notch1), hairy and enhancer of split-1 (Hes1), and vascular endothelial growth factor (Vegf), and the protein expression of NICD and HIF-1α, respectively.

Results

The liver/body weight ratios and number of Ki-67- and PCNA-positive cells were significantly lower in the experimental group than the control group, indicating lower levels of liver regeneration following the disruption of Notch signaling by Fli-06. The Hes1 and Vegf mRNA levels and NICD and HIF-1α protein expression levels were all down-regulated by Fli-06 treatment.

Conclusion

Notch–Hif-α signaling pathway activation plays an important role in liver regeneration, where it may contribute toward liver cell proliferation.

Dynamics of m6A RNA Methylome on the Hallmarks of Hepatocellular Carcinoma

Epidemiological data consistently rank hepatocellular carcinoma (HCC) as one of the leading causes of cancer-related deaths worldwide, often posing severe economic burden on health care. While the molecular etiopathogenesis associated with genetic and epigenetic modifications has been extensively explored, the biological influence of the emerging field of epitranscriptomics and its associated aberrant RNA modifications on tumorigenesis is a largely unexplored territory with immense potential for discovering new therapeutic approaches. In particular, the underlying cellular mechanisms of different hallmarks of hepatocarcinogenesis that are governed by the complex dynamics of m6A RNA methylation demand further investigation. In this review, we reveal the up-to-date knowledge on the mechanistic and functional link between m6A RNA methylation and pathogenesis of HCC.

Molecular pathways of liver regeneration: A comprehensive review

The liver is a unique parenchymal organ with a regenerative capacity allowing it to restore up to 70% of its volume. Although knowledge of this phenomenon dates back to Greek mythology (the story of Prometheus), many aspects of liver regeneration are still not understood. A variety of different factors, including inflammatory cytokines, growth factors, and bile acids, promote liver regeneration and control the final size of the organ during typical regeneration, which is performed by mature hepatocytes, and during alternative regeneration, which is performed by recently identified resident stem cells called "hepatic progenitor cells". Hepatic progenitor cells drive liver regeneration when hepatocytes are unable to restore the liver mass, such as in cases of chronic injury or excessive acute injury. In liver maintenance, the body mass ratio is essential for homeostasis because the liver has numerous functions; therefore, a greater understanding of this process will lead to better control of liver injuries, improved transplantation of small grafts and the discovery of new methods for the treatment of liver diseases. The current review sheds light on the key molecular pathways and cells involved in typical and progenitor-dependent liver mass regeneration after various acute or chronic injuries. Subsequent studies and a better understanding of liver regeneration will lead to the development of new therapeutic methods for liver diseases.

Histone Deacetylase Inhibitors in the Treatment of Hepatocellular Carcinoma: Current Evidence and Future Opportunities

Hepatocellular carcinoma (HCC) remains a major health problem worldwide with a continuous increasing prevalence. Despite the introduction of targeted therapies like the multi-kinase inhibitor sorafenib, treatment outcomes are not encouraging. The prognosis of advanced HCC is still dismal, underlying the need for novel effective treatments. Apart from the various risk factors that predispose to the development of HCC, epigenetic factors also play a functional role in tumor genesis. Histone deacetylases (HDACs) are enzymes that remove acetyl groups from histone lysine residues of proteins, such as the core nucleosome histones, in this way not permitting DNA to loosen from the histone octamer and consequently preventing its transcription. Considering that HDAC activity is reported to be up-regulated in HCC, treatment strategies with HDAC inhibitors (HDACIs) showed some promising results. This review focuses on the use of HDACIs as novel anticancer agents and explains the mechanisms of their therapeutic effects in HCC.

Regulatory long non-coding RNAs of hepatic stellate cells in liver fibrosis (Review)

Liver fibrosis (LF) is a continuous wound healing process caused by numerous chronic hepatic diseases and poses a major threat to human health. Activation of hepatic stellate cells (HSCs) is a critical event in the development of hepatic fibrosis. Long non-coding RNAs (lncRNAs) that are involved in HSC activation, participate in the development of LF and are likely to be therapeutic targets for LF. In the present review, the cellular signaling pathways of LF with respect to HSCs were discussed. In particular, this present review highlighted the current knowledge on the role of lncRNAs in activating or inhibiting LF, revealing lncRNAs that are likely to be biomarkers or therapeutic targets for LF. Additional studies should be performed to elucidate the potential of lncRNAs in the diagnosis and prognosis of LF and to provide novel therapeutic approaches for the reversion of LF.

The roles and activation of endocardial Notch signaling in heart regeneration

As a highly conserved signaling pathway in metazoans, the Notch pathway plays important roles in embryonic development and tissue regeneration. Recently, cardiac injury and regeneration have become an increasingly popular topic for biomedical research, and Notch signaling has been shown to exert crucial functions during heart regeneration as well. In this review, we briefly summarize the molecular functions of the endocardial Notch pathway in several cardiac injury and stress models. Although there is an increase in appreciating the importance of endocardial Notch signaling in heart regeneration, the mechanism of its activation is not fully understood. This review highlights recent findings on the activation of the endocardial Notch pathway by hemodynamic blood flow change in larval zebrafish ventricle after partial ablation, a process involving primary cilia, mechanosensitive ion channel Trpv4 and mechanosensitive transcription factor Klf2.

Matrine promotes hepatic oval cells differentiation into hepatocytes and alleviates liver injury by suppression of Notch signalling pathway

AIMS

Recent studies have shown that the hyperactive Notch pathway is involved in cirrhosis and hepatocellular carcinoma (HCC) development by regulating differentiation of hepatic oval cells (HOCs) into cancer cells. The aim of this study was to investigate whether matrine can alleviate liver injury and promote HOC differentiation into hepatocytes by suppression of Notch pathway.

MAIN METHODS

We evaluated the expression of Notch-1, Jagged-1, and Hes-1 in HCC tissue by immunohistochemistry. Stem cell characteristics of HOCs were evaluated by CCK-8, cell cycle, and apoptosis. The expression of Notch pathway, HOC markers and albumin (ALB) was detected by immunohistochemistry, QRT-PCR and western blotting. The effects of matrine in protecting liver in vivo were investigated in a rat Solt-Farber precancerous model.

KEY FINDINGS

We found an abnormal activated Notch pathway in HCC tissue, and the hyperactive Notch pathway was strongly associated with poor liver function in patients with cirrhosis with HCC. Using siNotch-1 to inhibit Notch pathway confirmed that Notch pathway could maintain stem cell characteristics of HOCs. Matrine inhibited stem cell characteristics of HOCs, the expression of Notch pathway and HOC markers but upregulated ALB. Matrine in combined with siNotch-1 RNA decreased the more potently inhibited HOC markers and Notch pathway. In rat Solt-Farber precancerous model, prophylactic application of matrine alleviated liver injury, downregulated Notch pathway and HOC markers, and upregulated ALB in a dose-dependent manner.

SIGNIFICANCE

Matrine could promote the differentiation of HOCs into hepatocytes by inhibiting the Notch signalling pathway and alleviate liver injury.

Delta-like Canonical Notch Ligand 1 in Patients Following Liver Transplantation-A Secondary Analysis of a Prospective Cohort Study

Opportunistic bacterial infections are dreaded risks in patients following liver transplantation (LTX), even though patients receive an antibiotic prophylaxis. The timely recognition of such an infection may be delayed, as culture-based diagnostic methods are linked with a relevant gap in performance. We measured plasma concentrations of Delta-like canonical Notch ligand 1 (DLL1) in 93 adult patients at seven consecutive time points after liver transplantation and correlated the results to the occurrence of culture-proven bacterial infection or a complicated clinical course (composite endpoint of two or more complications: graft rejection or failure, acute kidney failure, acute lung injury, or 90-day mortality). Patients exhibited elevated plasma concentrations after liver transplantation over the whole 28 d observation time. Patients with bacterial infection showed increased DLL1 levels compared to patients without infection. Persistent elevated levels of DLL1 on day 7 and afterward following LTX were able to indicate patients at risk for a complicated course. Plasma levels of DLL1 following LTX may be useful to support an earlier detection of bacterial infections in combination with C-reactive protein (CRP) and procalcitonin (PCT), or they may lead to risk stratification of patients as a single marker for post-operative complications. (Clinical Trial Notation. German Clinical Trials Register: DRKS00005480).

Organoids to model liver disease

The organoid model represents a major breakthrough in cell biology that has revolutionised biomedical research. Organoids are 3D physiological in vitro structures that recapitulate morphological and functional features of in vivo tissues and offer significant advantages over traditional cell culture methods. Liver organoids are of particular interest because of the pleiotropy of functions exerted by the human liver, their utility to model different liver diseases, and their potential application as cell-based therapies in regenerative medicine. Moreover, because they can be derived from patient tissues, organoid models offer new perspectives in personalised medicine and drug discovery. In this review, we discuss the current liver organoid models for the study of liver disease.

Potential of ileal bile acid transporter inhibition as a therapeutic target in Alagille syndrome and progressive familial intrahepatic cholestasis

Alagille syndrome (ALGS) and progressive familial intrahepatic cholestasis (PFIC) are rare, inherited cholestatic liver disorders that manifest in infants and children and are associated with impaired bile flow (ie cholestasis), pruritus and potentially fatal liver disease. There are no effective or approved pharmacologic treatments for these diseases (standard medical treatments are supportive only), and new, noninvasive options would be valuable. Typically, bile acids undergo biliary secretion and intestinal reabsorption (ie enterohepatic circulation). However, in these diseases, disrupted secretion of bile acids leads to their accumulation in the liver, which is thought to underlie pruritus and liver-damaging inflammation. One approach to reducing pathologic bile acid accumulation in the body is surgical biliary diversion, which interrupts the enterohepatic circulation (eg by diverting bile acids to an external stoma). These procedures can normalize serum bile acids, reduce pruritus and liver injury and improve quality of life. A novel, nonsurgical approach to interrupting the enterohepatic circulation is inhibition of the ileal bile acid transporter (IBAT), a key molecule in the enterohepatic circulation that reabsorbs bile acids from the intestine. IBAT inhibition has been shown to reduce serum bile acids and pruritus in trials of paediatric cholestatic liver diseases. This review explores the rationale of inhibition of the IBAT as a therapeutic target, describes IBAT inhibitors in development and summarizes the current data on interrupting the enterohepatic circulation as treatment for cholestatic liver diseases including ALGS and PFIC.

Effect of nicastrin on hepatocellular carcinoma proliferation and apoptosis through PI3K/AKT signalling pathway modulation

Background

Increasing evidence has proven that the γ-secretase complex plays significant roles in the carcinogenesis of malignancies. However, the independent effect of nicastrin (NCSTN), the largest constituent of the γ-secretase complex, on the progression of hepatocellular carcinoma (HCC) remains to be discovered.

Methods

In our study, we used open online databases, including the Oncomine database, GEPIA and KMPlotter, to analyse the expression of 4 genes and their correlation with prognosis in HCC. NCSTN expression in 60 HCC patients from our centre was determined by immunohistochemical staining and qRT-PCR. The clinical and prognostic significance of NCSTN expression were analysed statistically. Stable Sk-hep1 cell lines with NCSTN overexpression were established using lentivirus-based vectors, and RNAi technology was used to transiently downregulate NCSTN expression in HepG2 cell lines. Cell growth and apoptosis were assessed by using EdU, clone formation, flow cytometry and Western blotting assays.

Results

Bioinformatics analysis showed that NCSTN mRNA expression was generally higher in HCC tissues than in normal tissues according to a meta-analysis of 9 HCC datasets, excluding PS-1, PEN-2 and APH-1. Moreover, NCSTN was associated with a poor prognosis in HCC patients from The Cancer Genome Atlas (TCGA). Although the relationship between NCSTN levels and the clinicopathological features of HCC patients was not significant, a survival analysis of HCC patients from TCGA indicated that overall and disease-free survival were significantly associated with NCSTN expression. NCSTN expression in HCC cell lines regulated cell growth and apoptosis in vitro. NCSTN downregulation in HepG2 cells inhibited tumour growth ability in vivo. In addition, NCSTN downregulation in HepG2 cell lines decreased p-PI3K and p-Akt expression, and IGF1, a PI3K/Akt activator, neutralized the effects on PI3K and Akt phosphorylation. Moreover, NCSTN overexpression in Sk-hep1 cells activated the PI3K/Akt signalling pathway, and MK-2206, a PI3K/Akt inhibitor, reversed this activation according to Western blotting analysis.

Conclusions

We suggest that NCSTN serves as an oncogene in HCC by promoting growth and inhibiting apoptosis via the PI3K/Akt pathway, providing a potential novel therapeutic target for HCC treatment.

RNA-Seq transcriptome profiling in three liver regeneration models in rats: comparative analysis of partial hepatectomy, ALLPS, and PVL

The liver is a unique organ that has a phenomenal capacity to regenerate after injury. Different surgical procedures, including partial hepatectomy (PH), intraoperative portal vein ligation (PVL), and associated liver partition and portal vein ligation for staged hepatectomy (ALPPS) show clinically distinct recovery patterns and regeneration. The observable clinical differences likely mirror some underlying variations in the patterns of gene activation and regeneration pathways. In this study, we provided a comprehensive comparative transcriptomic analysis of gene regulation in regenerating rat livers temporally spaced at 24 h and 96 h after PH, PVL, and ALPPS. The time-dependent factors appear to be the most important determinant of post-injury alterations of gene expression in liver regeneration. Gene expression profile after ALPPS showed more similar expression pattern to the PH than the PVL at the early phase of the regeneration. Early transcriptomic changes and predicted upstream regulators that were found in all three procedures included cell cycle associated genes (E2F1, CCND1, FOXM1, TP53, and RB1), transcription factors (Myc, E2F1, TBX2, FOXM1), DNA replication regulators (CDKN1A, EZH2, RRM2), G1/S-transition regulators (CCNB1, CCND1, RABL6), cytokines and growth factors (CSF2, IL-6, TNF, HGF, VEGF, and EGF), ATM and p53 signaling pathways. The functional pathway, upstream, and network analyses revealed both unique and overlapping molecular mechanisms and pathways for each surgical procedure. Identification of molecular signatures and regenerative signaling pathways for each surgical procedure further our understanding of key regulators of liver regeneration as well as patient populations that are likely to benefit from each procedure.

NOTCH target gene HES5 mediates oncogenic and tumor suppressive functions in hepatocarcinogenesis

NOTCH receptor signaling plays a pivotal role in liver homeostasis and hepatocarcinogenesis. However, the role of NOTCH pathway mutations and the NOTCH target gene HES5 in liver tumorigenesis are poorly understood. Here we performed whole-exome sequencing of 54 human HCC specimens and compared the prevalence of NOTCH pathway component mutations with the TCGA-LIHC cohort (N = 364). In addition, we functionally characterized the NOTCH target HES5 and the patient-derived HES5-R31G mutation in vitro and in an orthotopic mouse model applying different oncogenic backgrounds, to dissect the role of HES5 in different tumor subgroups in vivo. We identified nonsynonymous mutations in 14 immediate NOTCH pathway genes affecting 24.1% and 16.8% of HCC patients in the two independent cohorts, respectively. Among these, the HES5-R31G mutation was predicted in silico to have high biological relevance. Functional analyses in cell culture showed that HES5 reduced cell migration and clonogenicity. Further analyses revealed that the patient-derived HES5-R31G mutant protein was non-functional due to loss of DNA binding and greatly reduced nuclear localization. Furthermore, HES5 exhibited a negative feedback loop by directly inhibiting the NOTCH target HES1 and downregulated the pro-proliferative MYC targets ODC1 and LDHA. Interestingly, HES5 inhibited MYC-dependent hepatocarcinogenesis, whereas it promoted AKT-dependent liver tumor formation and stem cell features in a murine model. Thus, NOTCH pathway component mutations are commonly observed in HCC. Furthermore, the NOTCH target gene HES5 has both pro- and anti-tumorigenic functions in liver cancer proposing a driver gene dependency and it promotes tumorigenesis with its interaction partner AKT.

A time-resolved multi-omic atlas of the developing mouse liver

Liver organogenesis and development are composed of a series of complex, well-orchestrated events. Identifying key factors and pathways governing liver development will help elucidate the physiological and pathological processes including those of cancer. We conducted multidimensional omics measurements including protein, mRNA, and transcription factor (TF) DNA-binding activity for mouse liver tissues collected from embryonic day 12.5 (E12.5) to postnatal week 8 (W8), encompassing major developmental stages. These data sets reveal dynamic changes of core liver functions and canonical signaling pathways governing development at both mRNA and protein levels. The TF DNA-binding activity data set highlights the importance of TF activity in early embryonic development. A comparison between mouse liver development and human hepatocellular carcinoma (HCC) proteomic profiles reveal that more aggressive tumors are characterized with the activation of early embryonic development pathways, whereas less aggressive ones maintain liver function-related pathways that are elevated in the mature liver. This work offers a panoramic view of mouse liver development and provides a rich resource to explore in-depth functional characterization.

Crenigacestat, a selective NOTCH1 inhibitor, reduces intrahepatic cholangiocarcinoma progression by blocking VEGFA/DLL4/MMP13 axis

Intrahepatic cholangiocarcinoma (iCCA) is a deadly disease with rising incidence and few treatment options. An altered expression and/or activation of NOTCH1–3 receptors has been shown to play a role in iCCA development and progression. In this study, we established a new CCA patient-derived xenograft model, which was validated by immunohistochemistry and transcriptomic analysis. The effects of Notch pathway suppression by the Crenigacestat (LY3039478)-specific inhibitor were evaluated in human iCCA cell lines and the PDX model. In vitro, LY3039478 significantly reduced Notch pathway components, including NICD1 and HES1, but not the other Notch receptors, in a panel of five different iCCA cell lines. In the PDX model, LY3039478 significantly inhibited the Notch pathway and tumor growth to the same extent as gemcitabine. Furthermore, gene expression analysis of iCCA mouse tissues treated with LY3039478 revealed a downregulation of VEGFA, HES1, and MMP13 genes. In the same tissues, DLL4 and CD31 co-localized, and their expression was significantly inhibited in the treated mice, as it happened in the case of MMP13. In an in vitro angiogenesis model, LY3039478 inhibited vessel formation, which was restored by the addition of MMP13. Finally, RNA-sequencing expression data of iCCA patients and matched surrounding normal liver tissues downloaded from the GEO database demonstrated that NOTCH1, HES1, MMP13, DLL4, and VEGFA genes were significantly upregulated in tumors compared with adjacent nontumorous tissues. These data were confirmed by our group, using an independent cohort of iCCA specimens. Conclusion: We have developed and validated a new iCCA PDX model to test in vivo the activity of LY3039478, demonstrating its inhibitory role in Notch-dependent angiogenesis. Thus, the present data provide new knowledge on Notch signaling in iCCA, and support the inhibition of the Notch cascade as a promising strategy for the treatment of this disease.

Adenosine Suppresses Cholangiocarcinoma Cell Growth and Invasion in Equilibrative Nucleoside Transporters-Dependent Pathway

Cholangiocarcinoma (CCA) is a lethal disease with increasing incidence worldwide. Previous study showed that CCA was sensitive to adenosine. Thereby, molecular mechanisms of CCA inhibition by adenosine were examined in this study. Our results showed that adenosine inhibited CCA cells via an uptake of adenosine through equilibrative nucleoside transporters (ENTs), instead of activation of adenosine receptors. The inhibition of ENTs by NBTI caused the inhibitory effect of adenosine to subside, while adenosine receptor antagonists, caffeine and CGS-15943, failed to do so. Intracellular adenosine level was increased after adenosine treatment. Also, a conversion of adenosine to AMP by adenosine kinase is required in this inhibition. On the other hand, inosine, which is a metabolic product of adenosine has very little inhibitory effect on CCA cells. This indicates that a conversion of adenosine to inosine may reduce adenosine inhibitory effect. Furthermore, there was no specific correlation between level of proinflammatory proteins and CCA responses to adenosine. A metabolic stable analog of adenosine, 2Cl-adenosine, exerted higher inhibition on CCA cell growth. The disturbance in intracellular AMP level also led to an activation of 5′ AMP-activated protein kinase (AMPK). Accordingly, we proposed a novel adenosine-mediated cancer cell growth and invasion suppression via a receptor-independent mechanism in CCA.

MFAP5 facilitates the aggressiveness of intrahepatic Cholangiocarcinoma by activating the Notch1 signaling pathway

BACKGROUND

Intrahepatic cholangiocarcinoma (ICC) is the second most common primary liver cancer. The dismal outcome of ICC patients is due to lack of early diagnosis, the aggressive biological behavior of ICC and the lack of effective therapeutic options. Early diagnosis and prognosis of ICC by non-invasive methods would be helpful in providing valuable information and developing effective treatment strategies.

METHODS

Expression of microfibrillar-associated protein 5 (MFAP5) in the serum of ICC patients was detected by ELISA. Human ICC specimens were immunostained by MFAP5 antibodies. The growth rate of human ICC cell lines treated with MFAP5 or MFAP5 shRNAs was examined by CCK8 and colony formation assays. Cell cycle analysis was performed with PI staining. The effect of MFAP5 inhibition was assessed by xenograft models in nude mice. RNA-seq and ATAC-seq analyses were used to dissect the molecular mechanism by which MFAP5 promoted ICC aggressiveness.

RESULTS

We identified MFAP5 as a biomarker for the diagnosis and prognosis of ICC. Upregulated MFAP5 is a common feature in aggressive ICC patients' tissues. Importantly, MFAP5 level in the serum of ICC patients and healthy individuals showed significant differential expression profiles. Furthermore, we showed that MFAP5 promoted ICC cell growth and G1 to S-phase transition. Using RNA-seq expression and ATAC-seq chromatin accessibility profiling of ICC cells with suppressed MFAP5 secretion, we showed that MFAP5 regulated the expression of genes involved in the Notch1 signaling pathway. Furthermore, FLI-06, a Notch signaling inhibitor, completely abolished the MFAP5-dependent transcriptional programs.

CONCLUSIONS

Raised MFAP5 serum level is useful for differentiating ICC patients from healthy individuals, and could be helpful in ICC diagnosis, prognosis and therapies.

Novel mutations in NOTCH2 gene in infants with neonatal cholestasis

One cause of neonatal cholestasis (NC) is paucity of intrahepatic bile ducts which can be associated with Alagille syndrome or non- syndromic. Alagille syndrome is caused by autosomal dominant mutations in the Notch signaling pathway ligand Jagged1 in 94% of patients and mutations in the NOTCH2 receptor in <1% of patients. This is a retrospective case series studying infants with neonatal cholestasis found to have variants of unknown significance (VOUS) in NOTCH2. Sorting intolerant from tolerant (SIFT) and polymorphism phenotyping (PolyPhen) were utilized to predict a damaging effect. Five infants with NC without other features of Alagille syndrome were found to have one copy of a VOUS in NOTCH2, predicted to be damaging by SIFT and PolyPhen. Our cases support the notion that NOTCH2 mutations may result in hypoplastic biliary system. Further characterization of these variants is important to assist with our clinical approach to NC.

An essential role of RNF187 in Notch1 mediated metastasis of hepatocellular carcinoma

Background

Aberrant activation of Notch signaling has been causally linked to the metastasis of hepatocellular carcinoma (HCC), however the underlying molecular mechanisms are still poorly understood. RING finger protein 187 (RNF187) was recently revealed to be a driver of several cancers, but its expression pattern and biological function in HCC are unknown.

Methods

The expression levels of Notch1 and RNF187 were assessed in two independent cohorts of HCC tissues, and modulation of Notch1 in HCC cells was performed to explore the regulatory role of Notch1 in HCC metastasis. RNA-sequencing (RNA-seq), bioinformatics analysis, luciferase reporter analysis, and chromatin immunoprecipitation assay (ChIP) were used to clarify the relationship between Notch1 signaling and its potential target Ring finger protein 187 (RNF187). Gain- and loss-of-function studies were used to dissect the role of Notch1-RNF187 signaling in promoting HCC metastasis. The impact of Notch1-RNF187 activity in determining clinical prognosis for HCC patients was evaluated by multivariate Cox regression.

Results

By RNA-seq, luciferase reporter analysis, and ChIP assay, RNF187 was confirmed to be a direct transcriptional target of Notch1, as Notch1 could activate RNF187 promoter whereas the pro-migratory and pro-invasive effects of Notch1 were significantly attenuated by RNF187 knockdown. Meanwhile, RNF187 silencing could attenuate the Notch1-dependent epithelial-mesenchymal transition (EMT). Moreover, overexpression of RNF187 counteracted the inhibitory effect of Notch1 knockdown on cancer progression. Importantly, HCC patients with high level of hepatic Notch1 expression had shorter disease-free survival (DFS) than those with low level of hepatic Notch1 expression. Furthermore, patients with high level of Notch1 and RNF187 co-expression showed the shortest DFS. The expression level of Notch1 and RNF187 was an independent prognostic factor for HCC.

Conclusions

For the first time we identified that RNF187 is an essential factor for Notch1 to promote invasion and metastasis of HCC. Of highly clinical relevance, we found that activation of Notch1-RNF187 correlates with a worse prognosis of HCC patients. These findings provide a solid foundation for developing novel strategies to tackle HCC metastasis.

Electronic supplementary material

The online version of this article (10.1186/s13046-019-1382-x) contains supplementary material, which is available to authorized users.

The roles of signaling pathways in liver repair and regeneration

The liver has remarkable regeneration potency that restores liver mass and sustains body hemostasis. Liver regeneration through signaling pathways following resection or moderate damages are well studied. Various cell signaling, growth factors, cytokines, receptors, and cell types implicated in liver regeneration undergo controlled hypertrophy and proliferation. Some aspects of liver regeneration have been discovered and many investigations have been carried out to identify its mechanisms. However, for optimizing liver regeneration more should be understood about mechanisms that control the growth of hepatocytes and other liver cell types in adults. The current paper deals with the possible applicability of liver regeneration signaling pathways as a target for therapeutic approaches and preventing various liver damages. Furthermore, the latest findings of spectrum-specific signaling pathway mechanisms that underlie liver regeneration are briefly described.

Pathobiology of inherited biliary diseases: a roadmap to understand acquired liver diseases

Bile duct epithelial cells, also known as cholangiocytes, regulate the composition of bile and its flow. Acquired, congenital and genetic dysfunctions in these cells give rise to a set of diverse and complex diseases, often of unknown aetiology, called cholangiopathies. New knowledge has been steadily acquired about genetic and congenital cholangiopathies, and this has led to a better understanding of the mechanisms of acquired cholangiopathies. This Review focuses on findings from studies on Alagille syndrome, polycystic liver diseases, fibropolycystic liver diseases (Caroli disease and congenital hepatic fibrosis) and cystic fibrosis-related liver disease. In particular, knowledge on the role of Notch signalling in biliary repair and tubulogenesis has been advanced by work on Alagille syndrome, and investigations in polycystic liver diseases have highlighted the role of primary cilia in biliary pathophysiology and the concept of biliary angiogenic signalling and its role in cyst growth and biliary repair. In fibropolycystic liver disease, research has shown that loss of fibrocystin generates a signalling cascade that increases β-catenin signalling, activates the NOD-, LRR- and pyrin domain-containing 3 inflammasome, and promotes production of IL-1β and other chemokines that attract macrophages and orchestrate the process of pericystic and portal fibrosis, which are the main mechanisms of progression in cholangiopathies. In cystic fibrosis-related liver disease, lack of cystic fibrosis transmembrane conductance regulator increases the sensitivity of epithelial Toll-like receptor 4 that sustains the secretion of nuclear factor-κB-dependent cytokines and peribiliary inflammation in response to gut-derived products, providing a model for primary sclerosing cholangitis. These signalling mechanisms may be targeted therapeutically and they offer a possibility for the development of novel treatments for acquired cholangiopathies.

miR-515-5p and Notch1 as New Diagnostic Markers of Hepatocellular Carcinoma

Background: Modifications of miRNA expression have been related to various types of cancers including hepatocellular carcinoma (HCC). miRNAs directly act as repressors of gene expression, as they reside in fragile sites, as well as cancer-related genomic regions. Notch signaling is a conserved evolutionary pathway that controls cell functions. The dysregulation of this pathway leads to different diseases such as cancer. Objectives: This study aimed to investigate the role of miR-515-5p and Notch1 as new diagnostic markers in HCC. Methods: Forty formalin fixed paraffin embedded (FFPE) autopsy blocks and 40 FFPE normal liver tissues were selected from the archives of the pathology of Imam Reza hospital, Tabriz, Iran. Real-time polymerase chain reaction (PCR) was used for gene expression. Immune histochemistry method was used for detecting notch1 in normal and cancer FFPE tissues. Hematoxylin and eosin staining was also used for the diagnosis of normal and cancerous tissues. Results: miR-515-5P showed higher expression in the cancer group compared to the normal group (4.7 fold). Hematoxylin and eosin staining of HCC tissues showed significant color intensity than that of normal tissues. Immune histochemistry results revealed significant Ag-Ab reaction in the cancer group. In this study, we analyzed miRNA gene expression and notch 1 level in HCC patients. miRNA dysregulation has been found in a large variety of HCCs. Hepatocarcinogenesis was associated with the expression level of miR-515-5p with carcinogenesis. Moreover, notch1 was a key protein in liver cell fate and a progressive molecule in HCC. Conclusion: Our study demonstrated the main role of miR-515-5p in the pathogenesis of HCC. Likewise, it disclosed the expression of these genes could be utilized in HCC prognosis.

Suppression of YAP/TAZ-Notch1-NICD axis by bromodomain and extraterminal protein inhibition impairs liver regeneration

Background and aims: Biological mechanisms that control liver regeneration remain poorly defined. However, these mechanisms are remarkable issues in the clinic that affect management of hepatic loss caused by liver surgery, traumatic injury, chronic infection, or liver poisoning. Increasing evidence has shown that various growth factors, cytokines, and metabolic signaling pathways affect the liver regenerative process. Our aim is to study the effect of bromodomain and extraterminal (BET) protein inhibition on liver regeneration and its mechanism.

Methods: We studied the role of BET protein inhibitor, JQ1, in liver regeneration in a mouse model after 70% partial hepatectomy (PH). We evaluated yes-associated protein (YAP)/transcriptional co-activator with PDZ-binding motif (TAZ) and Notch signaling pathways, which were affected by BET protein inhibitor in mouse hepatic tissues and primary hepatocytes in vivo and AML12 cell lines in vitro. We evaluated the relationship of YAP/TAZ and Notch signaling pathway using YAP/TAZ pathway inhibitor in liver regeneration in vivo. Moreover, we analyzed the relationship of YAP/TAZ and Notch signaling pathways via overexpression or RNA silencing of Yap in AML12 cells. Furthermore, we used Yap overexpression mouse model to examine whether it can rescue liver regeneration damage caused by inhibition of BET proteins.

Results: In this study, we report that BET protein inhibitor JQ1 molecule impairs the early phase of liver regeneration in a mouse model after 70% PH. Mechanistically, YAP/TAZ and Notch1-NICD pathways were suppressed by BET protein inhibitor in mouse hepatic tissues and primary hepatocytes in vivo and mouse AML12 cell lines in vitro. By using YAP/TAZ pathway inhibitor, we confirmed that the liver regeneration and the activation of Notch pathway were impaired by the inhibition of YAP/TAZ pathway in vivo. Furthermore, the study showed that Yap knockdown by shRNA in normal mouse hepatic cell line downregulated Notch1 signal transduction, whereas Yap overexpression promoted Notch1-NICD signals. Specific overexpression of Yap in mouse liver could rescue the effect of BET protein inhibition on liver regeneration injury.

Conclusion: These results revealed the crucial role of the YAP/TAZ-Notch1-NICD axis in liver regeneration. Therefore, BET protein inhibitors must be used in caution in the treatment of hepatic diseases by reason of its suppressive roles in liver regeneration.

Distinct notch signaling expression patterns between nucleoside and nucleotide analogues treatment for hepatitis B virus infection

Nucleos(t)ide analogues therapies are currently approved for the treatment of chronic hepatitis B virus (HBV) infection, which effectively suppress HBV replication and correlate with the anti-HBV-specific immune response. Notch signaling serves pleiotropic roles in the immune system that also contribute to virus-specific immunity. In this study, we assessed Notch signal-related gene expression after administrating nucleoside or nucleotide analogues to HBV-replicating cells and clinical liver tissues. We found distinct Notch signaling expression patterns under nucleos(t)ide analogues therapies, with high expression for nucleotide analogues (adefovir pivoxil or tenofovir disoproxil fumarate) and low expression for nucleoside analogues (lamivudine or entecavir) in the presence of HBV infection. Furthermore, activation of mammalian target of rapamycin (mTOR)-Akt (Ser473) phosphorylation was also observed after nucleotide analogue treatment. In conclusion, nucleoside and nucleotide analogues displayed different patterns of Notch signaling activity under HBV infection, and the induction of mTORC2-Akt (Ser473) phosphorylation may contribute to nucleotide analogues-mediated Notch signaling activation.

Identification of the xenograft and its ascendant sphere-forming cell line as belonging to EBV-induced lymphoma, and characterization of the status of sphere-forming cells

BACKGROUND

We have characterized the human cell line arised from the Epstein-Barr virus (EBV) positive multiple myeloma aspirate subjected to the long-term cultivation. This cell line has acquired the ability to form free-floating spheres and to produce a xenograft upon transplantation into NOD/SCID mice.

METHODS

Cells from both in vitro culture and developed xenografts were investigated with a number of analytical approaches, including pathomorphological analysis, FISH analysis, and analysis of the surface antigens and of the VDJ locus rearrangement.

RESULTS

The obtained results, as well as the confirmed presence of EBV, testify that both biological systems are derived from B-cells, which, in turn, is a progeny of the EBV-transformed B-cellular clone that supplanted the primordial multiple myeloma cells. Next we assessed whether cells that (i) were constantly present in vitro in the investigated cell line, (ii) were among the sphere-forming cells, and (iii) were capable of internalizing a fluorescent TAMRA-labeled DNA probe (TAMRA+ cells) belonged to one of the three types of undifferentiated bone marrow cells of a multiple myeloma patient: CD34+ hematopoietic stem cells, CD90+ mesenchymal stem cells, and clonotypic multiple myeloma cell.

CONCLUSION

TAMRA+ cells were shown to constitute the fourth independent subpopulation of undifferentiated bone marrow cells of the multiple myeloma patient. We have demonstrated the formation of ectopic contacts between TAMRA+ cells and cells of other types in culture, in particular with CD90+ mesenchymal stem cells, followed by the transfer of some TAMRA+ cell material into the contacted cell.

Role of the Angiogenic Factors in Cholangiocarcinoma

Angiogenesis plays a fundamental role in tumor growth and progression. It is regulated by several growth factors, including vascular endothelial growth factor protein family (VEGF) and its receptors, which are probably the most important factors responsible for the development of new vessels. The VEGF family includes several members: VEGF-A, VEGF-B, VEGF-C, VEGF-D, VEGF-E, placental growth factor (PlGF), and their receptors VEGFR-1, VEGFR-2 and VEGFR-3. Other relevant factors are represented by angiopoietins, thrombospondin-1, and endothelins. However, since the therapeutic benefit associated with VEGF-targeted therapy is really complex, a better understanding of these pathways will lead to future advances in the use of these agents for clinic management of tumors. Here we present a review regarding the role of angiogenic factors in cholangiocarcinoma, which arise from cholangiocytes, the epithelial cells of bile ducts. They are rare and aggressive neoplasms with a poor prognosis and limited treatment options, classified as intrahepatic, perihilar, and distal cholangiocarcinoma based on their anatomical location. Therefore, the identification of specific signaling pathways or new tumor biomarkers is crucial in order to develop more effective anti-angiogenic therapies.

Transcriptome analysis reveals the mechanism of the effect of flower tea Coreopsis tinctoria on hepatic insulin resistance

Non-Camellia tea and herbal medicine help prevent the development of diabetes and other metabolic diseases. Previous studies revealed that Coreopsis tinctoria (CT) flower tea increases insulin sensitivity and, in some high-fat diet (HFD)-fed rats, even prevents hepatic metabolic disorders. However, the molecular mechanisms by which CT improves insulin resistance are not known. In this study, six-week-old rats were fed a normal diet (ND), an HFD or an HFD supplemented with CT for 8 weeks. Serum samples were collected, and the livers were extracted for RNA-seq gene expression analysis. Real-time PCR and western blotting further verified the RNA-seq results. In our results, dietary CT ameliorated HFD-induced hepatosteatosis, glucose intolerance, and insulin resistance. In the HFD group, 1667 differentially expressed genes (DEGs) were identified compared with the ND group. In the CT group, 327 DEGs were identified compared with the HFD group. Some of these DEGs were related to insulin signalling, hepatic lipogenesis and glucose homeostasis. This study suggested that insulin resistance with hyperinsulinaemia, and not insulin insufficiency, is an early problem in HFD-fed rats, and CT downregulates insulin secretion genes (e.g., Rasd1, Stxbp1 and Sfxn1). Hepatic gene and protein expression analyses indicated that the regulatory effects of CT on glucose and lipid homeostasis are likely mediated via the Akt/FoxO1 signalling pathway and are regulated by the transcription factors hairy and enhancer of split 1 (HES1) and small heterodimer partner (SHP). Our study provides transcriptomic evidence of the complex pathogenic mechanism involved in hepatic insulin resistance and proves that supplementation with CT improves insulin resistance at a global scale.

Targeted Therapies in Cholangiocarcinoma: Emerging Evidence from Clinical Trials

Cholangiocarcinoma (CCA) is a highly-aggressive malignancy arising from the biliary tree, characterized by a steady increase in incidence globally and a high mortality rate. Most CCAs are diagnosed in the advanced and metastatic phases of the disease, due to the paucity of signs and symptoms in the early stages. This fact, along with the poor results of the local and systemic therapies currently employed, is responsible for the poor outcome of CCA patients and strongly supports the need for novel therapeutic agents and strategies. In recent years, the introduction of next-generation sequencing technologies has opened new horizons for a better understanding of the genetic pathophysiology of CCA and, consequently, for the identification and evaluation of new treatments tailored to the molecular features or alterations progressively elucidated. In this review article, we describe the potential targets under investigation and the current molecular therapies employed in biliary tract cancers. In addition, we summarize the main drugs against CCA under evaluation in ongoing trials and describe the preliminary data coming from these pioneering studies.

Notch signaling facilitates hepatitis B virus covalently closed circular DNA transcription via cAMP response element-binding protein with E3 ubiquitin ligase-modulation

Notch1 is regulated by E3 ubiquitin ligases, with proteasomal degradation of the Notch intracellular domain affecting the transcription of target genes. cAMP response element-binding protein (CREB) mediates the transcription of hepatitis B virus (HBV) covalently closed circular DNA (cccDNA). We assessed the relationship between HBV cccDNA and Notch signaling activities. HBV cccDNA levels and relative gene expression were evaluated in HBV-replicating cells treated with Jagged1 shRNA and a γ-secretase inhibitor. The effects of these factors in surgically resected clinical samples were also assessed. Notch inhibition suppressed HBV cccDNA and CREB-related expression but increased ITCH and NUMB levels. Proteasome inhibitor augmented HBV cccDNA, restored Notch and CREB expression, and inhibited ITCH and NUMB function. Increased HBV cccDNA was observed after ITCH and NUMB blockage, even after treatment with the adenylate cyclase activator forskolin; protein kinase A (PKA) inhibitor had the opposite effect. Notch activation and E3 ligase inactivation were observed in HBV-positive cells in clinical liver tissue. Collectively, these findings reveal that Notch signaling activity facilitates HBV cccDNA transcription via CREB to trigger the downstream PKA-phospho-CREB cascade and is regulated by E3 ubiquitin ligase-modulation of the Notch intracellular domain.

Cancer stem cells in hepatocellular carcinoma: an overview and promising therapeutic strategies

The poor clinical outcome of hepatocellular carcinoma (HCC) patients is ascribed to the resistance of HCC cells to traditional treatments and tumor recurrence after curative therapies. Cancer stem cells (CSCs) have been identified as a small subset of cancer cells which have high capacity for self-renewal, differentiation and tumorigenesis. Recent advances in the field of liver CSCs (LCSCs) have enabled the identification of CSC surface markers and the isolation of CSC subpopulations from HCC cells. Given their central role in cancer initiation, metastasis, recurrence and therapeutic resistance, LCSCs constitute a therapeutic opportunity to achieve cure and prevent relapse of HCC. Thus, it is necessary to develop therapeutic strategies to selectively and efficiently target LCSCs. Small molecular inhibitors targeting the core stemness signaling pathways have been actively pursued and evaluated in preclinical and clinical studies. Other alternative therapeutic strategies include targeting LCSC surface markers, interrupting the CSC microenvironment, and altering the epigenetic state. In this review, we summarize the properties of CSCs in HCC and discuss novel therapeutic strategies that can be used to target LCSCs.

Epistatic Association of CD14 and NOTCH2 Genetic Polymorphisms with Biliary Atresia in a Southern Chinese Population

Biliary atresia (BA) is the most common cause of endstage liver disease in infants with poor prognosis and high mortality. The etiology of BA is still unknown, but the genetic factors have been considered as an important player in BA. We investigated the association of two cis-regulated variants in CD14 (rs2569190) and NOTCH2 (rs835576) with BA susceptibility, using the largest case-control cohort, totaling 506 BA patients and 1,473 healthy controls in a Southern Chinese population. Significant epistatic interaction between the two variants in our samples was observed (p = 8.1E-03; OR = 2.78; 95% CI: 1.32-5.88). The expression of CD14 and NOTCH2 in the BA group was consistently lower than that in the control (CC) group (0.31 ± 0.02 versus 1.00 ± 0.14; p < 0.001), which might be related to the genetic susceptibility of the genes awaiting further validation.

STAT3-induced upregulation of long noncoding RNA HNF1A-AS1 promotes the progression of oral squamous cell carcinoma via activating Notch signaling pathway

Long non-coding RNAs (lncRNAs) are a group of biomarkers which can regulate the biological processes of various human cancers. LncRNA HNF1A-AS1 has been reported in human cancers for its oncogenic role. This study focused on the biological function and molecular mechanism of HNF1A-AS1 in oral squamous cell carcinoma (OSCC). The high expression of HNF1A-AS1 was examined in OSCC tissues and cell lines. Kaplan Meier method revealed that high expression of HNF1A-AS1 predicted poor prognosis for patients with OSCC. Results of loss-of-function assays demonstrated that silenced HNF1A-AS1 inhibited the proliferation, migration and epithelial-mesenchymal transition (EMT) of OSCC cells. Mechanically, HNF1A-AS1 was positively regulated by the transcription factor STAT3. Recently, Notch signaling pathway has been reported in human malignancies. In this study, we analyzed the correlation between HNF1A-AS1 and Notch signaling pathway. It was uncovered that the expression of Notch1 and Hes1 (the core factors of Notch signaling pathway) was negatively regulated by HNF1A-AS1 knockdown. Rescue assays further demonstrated the positive regulatory effects of HNF1A-AS1 on Notch signaling pathway in OSCC. In conclusion, upregulation of HNF1A-SA1 induced by transcription factor STAT3 promotes OSCC progression by activating Notch signaling pathway.

Regulation of periostin expression by Notch signaling in hepatocytes and liver cancer cell lines

Notch signaling is involved in both differentiation of hepatocyte progenitors and hepatocellular carcinoma (HCC). The mechanism whereby Notch signaling regulates cellular transformation in hepatocytes is still controversial. This study investigated the impact of overexpressing truncated intracellular Notch1 (NICD1) on transcriptomic profiles of immortalized human hepatocytes. RNA sequencing and gene ontology enrichment analysis revealed that extracellular matrix organization and hyaluronan biosynthesis process gene sets are among those affected by Notch hyperactivation. The relationship between Notch signaling and periostin, an extracellular matrix protein highly expressed in HCC, were further studied. Modulating Notch signaling through NICD1 overexpression or treatment with a gamma secretase inhibitor resulted in increased or decreased periostin expression, respectively, in HCC and liver bile duct carcinoma cell lines. Based on The Cancer Genome Atlas database, mRNA levels of NOTCH1 and POSTN are positively correlated in tumor tissues but not in nontumor tissues. Two consensus RBPJ binding motifs were identified in the -3932/-3921 and + 2522/+2533 bp of POSTN regulatory regions, and NOTCH1 is associated with these binding sites in a liver bile duct carcinoma cell line. Taken together, these results indicate that Notch signaling directly regulates transcription of POSTN in hepatocytes and liver cancer cell lines and may be a candidate for drug targeting in liver cancer.

Triptolide impairs thioredoxin system by suppressing Notch1-mediated PTEN/Akt/Txnip signaling in hepatocytes

Triptolide (TP) is the main ingredient of Chinese herb Tripterygium wilfordii Hook f. (TWHF). Despite of its multifunction in pharmaceutics, accumulating evidences showed that TP caused obvious hepatotoxicity in clinic. The current study investigated the role of Notch1 signaling in TP-induced hepatotoxicity. Our data indicated that TP inhibited the protein expression of Notch1 and its active form Notch intracellular domain (NICD) leading to increased PTEN (phosphatase and tensin homolog deleted on chromosome ten) expression. Moreover, PTEN triggered Txnip (thioredoxin-interacting protein) activation by inhibiting Akt phosphorylation, which resulted in reduction of Trx (thioredoxin). In conclusion, TP caused liver injury through initiating oxidative stress in hepatocyte. This study indicated the potency of Notch1 to protect against TP-induced hepatotoxicity.

Downregulation of Hes1 expression in experimental biliary atresia and its effects on bile duct structure

AIM

To analyze the expression and function of the Notch signaling target gene Hes1 in a rhesus rotavirus-induced mouse biliary atresia model.

METHODS

The morphologies of biliary epithelial cells in biliary atresia patients and in a mouse model were examined by immunohistochemical staining. Then, the differential expression of Notch signaling pathway-related molecules was investigated. Further, the effects of the siRNA-mediated inhibition of Hes1 expression were examined using a biliary epithelial cell 3D culture system.

RESULTS

Both immature (EpCAM⁺) and mature (CK19⁺) biliary epithelial cells were detected in the livers of biliary atresia patients without a ductile structure and in the mouse model with a distorted bile duct structure. The hepatic expression of transcripts for most Notch signaling molecules were significantly reduced on day 7 but recovered to normal levels by day 14, except for the target molecule Hes1, which still exhibited lower mRNA and protein levels. Expression of the Hes1 transcriptional co-regulator, RBP-Jκ was also reduced. A 3D gel culture system promoted the maturation of immature biliary epithelial cells, with increased expression of CK19⁺ cells and the formation of a duct-like structure. The administration of Hes1 siRNA blocked this process. As a result, the cells remained in an immature state, and no duct-like structure was observed.

CONCLUSION

Our data indicated that Hes1 might contribute to the maturation and the cellular structure organization of biliary epithelial cells, which provides new insight into understanding the pathology of biliary atresia.

Notch signaling pathway regulates cell cycle in proliferating hepatocytes involved in liver regeneration

BACKGROUND AND AIM

It has been well documented that Notch signaling is involved in liver regeneration. However, the exact molecular mechanism mediating this process is not fully elucidated. The current study aimed to investigate the role of Notch signaling regulating cell cycle in proliferating hepatocytes in liver regeneration after partial hepatectomy (PHx, 67% resection) and the related molecular mechanism.

METHODS

Partial hepatectomy was performed in Sprague Dawley rats, and remnant livers were harvested 0, 1, 3, 5, and 7 days after operation, and primary hepatocytes were isolated to investigate the molecular mechanism.

RESULTS

Notch signaling activation and hepatocyte proliferation were significantly increased after PHx, while treatment with FLI-06, the inhibitor of γ-secreting enzyme, blocked these trends. Besides, inhibition of Notch signaling led to dysregulation of cell cycle and cell-cycle components. Furthermore, Akti-1/2 (a selective Akt inhibitor) and PX-478 (a selective Hif-1α inhibitor) inhibited hepatocyte proliferation and liver regeneration after PHx, and the effect of downstream molecules activation by Jagged-1 (Notch-1 ligand) in hepatocytes was abolished by FLI-06, Akti-1/2, and PX-478.

CONCLUSION

The current study demonstrated for the first time that Notch signaling regulated cell cycle in proliferating hepatocytes involved in liver regeneration through NICD/Akt Akt/Hif-1α pathway.

Deregulation of the Notch pathway as a common road in viral carcinogenesis

The Notch pathway is a conserved signaling pathway and a form of direct cell-cell communication related to many biological processes during development and adulthood. Deregulation of the Notch pathway is involved in many diseases, including cancer. Almost 20% of all cancer cases have an infectious etiology, with viruses responsible for at least 1.5 million new cancer cases per year. Seven groups of viruses have been classified as oncogenic: hepatitis B and C viruses (HBV and HCV respectively), Epstein-Barr virus (EBV), Kaposi sarcoma-associated herpesvirus (KSHV), human T lymphotropic virus (HTLV-1), human papillomavirus (HPV), and Merkel cell polyomavirus (MCPyV). These viruses share the ability to manipulate a variety of cell pathways that are critical in proliferation and differentiation, leading to malignant transformation. Viral proteins interact directly or indirectly with different members of the Notch pathway, altering their normal function. This review focuses exclusively on the direct interactions of viral oncoproteins with Notch elements, providing a deeper understanding of the dual behavior of the Notch pathway as activator or suppressor of neoplasia in virus-related cancers.

WW and C2 domain-containing proteins regulate hepatic cell differentiation and tumorigenesis through the hippo signaling pathway

The Hippo pathway regulates cell differentiation, proliferation, and apoptosis. Upon activation, it inhibits the import of the transcriptional coactivator yes-associated protein (YAP) into the nucleus, thus suppressing transcription of pro-proliferative genes. Hence, dynamic and precise control of the Hippo pathway is crucial for organ size control and the prevention of tumor formation. Hippo signaling is controlled by a growing number of upstream regulators, including WW and C2 domain-containing (WWC) proteins, which trigger a serine/threonine kinase pathway. One component of this is the large tumor suppressor (LATS) kinase, which phosphorylates YAP, trapping it in the cytoplasm. WWC proteins have been shown to interact with LATS in vitro and stimulate its kinase activity, thus directly promoting cytoplasmic accumulation of phosphorylated YAP. However, the function of the WWC proteins in the regulation of cell proliferation, organ size control, and tumor prevention in vivo has not yet been determined. Here, we show that loss of hepatic WWC expression in mice leads to tissue overgrowth, inflammation, fibrosis, and formation of liver carcinoma. WWC-deficient mouse livers display reduced LATS activity, increased YAP-mediated gene transcription, and enhanced proliferation of hepatic progenitor cells. In addition, loss of WWC expression in the liver accelerates the turnover of angiomotin proteins, which act as negative regulators of YAP activity.

CONCLUSION

Our data define an essential in vivo function for WWC proteins as regulators of canonical and noncanonical Hippo signaling in hepatic cell growth and liver tumorigenesis. Thus, expression of WWC proteins may serve as novel prognostic factors in human liver carcinoma. (Hepatology 2018;67:1546-1559).