Development of a novel mouse model of hepatocellular carcinoma with nonalcoholic steatohepatitis using a high-fat, choline-deficient diet and intraperitoneal injection of diethylnitrosamine

Targeting squalene epoxidase restores anti-PD-1 efficacy in metabolic dysfunction-associated steatohepatitis-induced hepatocellular carcinoma

OBJECTIVE

Squalene epoxidase (SQLE) promotes metabolic dysfunction-associated steatohepatitis-associated hepatocellular carcinoma (MASH-HCC), but its role in modulating the tumour immune microenvironment in MASH-HCC remains unclear.

DESIGN

We established hepatocyte-specific Sqle transgenic (tg) and knockout mice, which were subjected to a choline-deficient high-fat diet plus diethylnitrosamine to induce MASH-HCC. SQLE function was also determined in orthotopic and humanised mice. Immune landscape alterations of MASH-HCC mediated by SQLE were profiled by single-cell RNA sequencing and flow cytometry.

RESULTS

Hepatocyte-specific Sqle tg mice exhibited a marked increase in MASH-HCC burden compared with wild-type littermates, together with decreased tumour-infiltrating functional IFN-γ+ and Granzyme B+ CD8+ T cells while enriching Arg-1+ myeloid-derived suppressor cells (MDSCs). Conversely, hepatocyte-specific Sqle knockout suppressed tumour growth with increased cytotoxic CD8+ T cells and reduced Arg-1+ MDSCs, inferring that SQLE promotes immunosuppression in MASH-HCC. Mechanistically, SQLE-driven cholesterol accumulation in tumour microenvironment underlies its effect on CD8+ T cells and MDSCs. SQLE and its metabolite, cholesterol, impaired CD8+ T cell activity by inducing mitochondrial dysfunction. Cholesterol depletion in vitro abolished the effect of SQLE-overexpressing MASH-HCC cell supernatant on CD8+ T cell suppression and MDSC activation, whereas cholesterol supplementation had contrasting functions on CD8+ T cells and MDSCs treated with SQLE-knockout supernatant. Targeting SQLE with genetic ablation or pharmacological inhibitor, terbinafine, rescued the efficacy of anti-PD-1 treatment in MASH-HCC models.

CONCLUSION

SQLE induces an impaired antitumour response in MASH-HCC via attenuating CD8+ T cell function and augmenting immunosuppressive MDSCs. SQLE is a promising target in boosting anti-PD-1 immunotherapy for MASH-HCC.

Spatial Omics Reveals that Cancer-Associated Glycan Changes Occur Early in Liver Disease Development in a Western Diet Mouse Model of MASLD

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a progressive disease and comprises different stages of liver damage; it is significantly associated with obese and overweight patients. Untreated MASLD can progress to life-threatening end-stage conditions, such as cirrhosis and liver cancer. N-Linked glycosylation is one of the most common post-translational modifications in the cell surface and secreted proteins. N-Linked glycan alterations have been established to be signatures of liver diseases. However, the N-linked glycan changes during the progression of MASLD to liver cancer are still unknown. Here, we induced different stages of MASLD in mice and liver-cancer-related phenotypes and elucidated the N-glycome profile during the progression of MASLD by quantitative and qualitative profiling in situ using matrix-assisted laser desorption ionization (MALDI) imaging mass spectrometry (IMS). Importantly, we identified specific N-glycan structures including fucosylated and highly branched N-linked glycans at very early stages of liver injury (steatosis), which in humans are associated with cancer development, establishing the importance of these modifications with disease progression. Finally, we report that N-linked glycan alterations can be observed in our models by MALDI-IMS before liver injury is identified by histological analysis. Overall, we propose these findings as promising biomarkers for the early diagnosis of liver injury in MASLD.

New and Old Key Players in Liver Cancer

Liver cancer represents a major health problem worldwide with growing incidence and high mortality, hepatocellular carcinoma (HCC) being the most frequent. Hepatocytes are likely the cellular origin of most HCCs through the accumulation of genetic alterations, although hepatic progenitor cells (HPCs) might also be candidates in specific cases, as discussed here. HCC usually develops in a context of chronic inflammation, fibrosis, and cirrhosis, although the role of fibrosis is controversial. The interplay between hepatocytes, immune cells and hepatic stellate cells is a key issue. This review summarizes critical aspects of the liver tumor microenvironment paying special attention to platelets as new key players, which exert both pro- and anti-tumor effects, determined by specific contexts and a tight regulation of platelet signaling. Additionally, the relevance of specific signaling pathways, mainly HGF/MET, EGFR and TGF-β is discussed. HGF and TGF-β are produced by different liver cells and platelets and regulate not only tumor cell fate but also HPCs, inflammation and fibrosis, these being key players in these processes. The role of C3G/RAPGEF1, required for the proper function of HGF/MET signaling in HCC and HPCs, is highlighted, due to its ability to promote HCC growth and, regulate HPC fate and platelet-mediated actions on liver cancer.

Impact of elobixibat on liver tumors, microbiome, and bile acid levels in a mouse model of nonalcoholic steatohepatitis

BACKGROUND

Elevated bile acid levels have been associated with liver tumors in fatty liver. Ileal bile acid transporter inhibitors may inhibit bile acid absorption in the distal ileum and increase bile acid levels in the colon, potentially decreasing the serum and hepatic bile acid levels. This study aimed to investigate the impact of these factors on liver tumor.

METHODS

C57BL/6J mice received a one-time intraperitoneal injection of 25-mg/kg diethylnitrosamine. They were fed a choline-deficient high-fat diet for 20 weeks starting from 8 weeks of age, with or without elobixibat (EA Pharma, Tokyo, Japan).

RESULTS

Both groups showed liver fat accumulation and fibrosis, with no significant differences between the two groups. However, mice with elobixibat showed fewer liver tumors. The total serum bile acid levels, including free, tauro-conjugated, glyco-conjugated, and tauro-α/β-muricholic acids in the liver, were noticeably reduced following elobixibat treatment. The proportion of gram-positive bacteria in feces was significantly lower in the group treated with elobixibat (5.4%) than in the group without elobixibat (33.7%).

CONCLUSION

Elobixibat suppressed tumor growth by inhibiting bile acid reabsorption, and decreasing total bile acid and primary bile acid levels in the serum and liver. Additionally, the presence of bile acids in the colon may have led to a significant reduction in the proportion of gram-positive bacteria, potentially resulting in decreased secondary bile acid synthesis.

Loss of cis-PTase function in the liver promotes a highly penetrant form of fatty liver disease that rapidly transitions to hepatocellular carcinoma

Obesity-linked fatty liver is a significant risk factor for hepatocellular carcinoma (HCC)1,2; however, the molecular mechanisms underlying the transition from non-alcoholic fatty liver disease (NAFLD) to HCC remains unclear. The present study explores the role of the endoplasmic reticulum (ER)-associated protein NgBR, an essential component of the cis-prenyltransferases (cis-PTase) enzyme3, in chronic liver disease. Here we show that genetic depletion of NgBR in hepatocytes of mice (N-LKO) intensifies triacylglycerol (TAG) accumulation, inflammatory responses, ER/oxidative stress, and liver fibrosis, ultimately resulting in HCC development with 100% penetrance after four months on a high-fat diet. Comprehensive genomic and single cell transcriptomic atlas from affected livers provides a detailed molecular analysis of the transition from liver pathophysiology to HCC development. Importantly, pharmacological inhibition of diacylglycerol acyltransferase-2 (DGAT2), a key enzyme in hepatic TAG synthesis, abrogates diet-induced liver damage and HCC burden in N-LKO mice. Overall, our findings establish NgBR/cis-PTase as a critical suppressor of NAFLD-HCC conversion and suggests that DGAT2 inhibition may serve as a promising therapeutic approach to delay HCC formation in patients with advanced non-alcoholic steatohepatitis (NASH).

Naringin-Dextrin Nanocomposite Abates Diethylnitrosamine/Acetylaminofluorene-Induced Lung Carcinogenesis by Modulating Oxidative Stress, Inflammation, Apoptosis, and Cell Proliferation

Nanotechnology has proven advantageous in numerous scientific applications, one being to enhance the delivery of chemotherapeutic agents. This present study aims to evaluate the mechanisms underlying the chemopreventive action of naringin-dextrin nanocomposites (Nar-Dx-NCs) against diethylnitrosamine (DEN)/2-acetylaminofluorene (2AAF)-induced lung carcinogenesis in male Wistar rats. DEN was administered intraperitoneally (i.p.) (150 mg/kg/week) for two weeks, followed by the oral administration of 2AAF (20 mg/kg) four times a week for three weeks. Rats receiving DEN/2AAF were concurrently treated with naringin or Nar-Dx-NCs orally at a dose of 10 mg/kg every other day for 24 weeks. Naringin and Nar-Dx-NCs treatments prevented the formation of tumorigenic cells within the alveoli of rats exposed to DEN/2AAF. These findings were associated with a significant decrease in lipid peroxidation, upregulation of antioxidant enzyme (glutathione peroxidase and superoxide dismutase) activity, and enhanced glutathione and nuclear factor erythroid 2-related factor 2 expression in the lungs. Naringin and Nar-Dx-NCs exerted anti-inflammatory actions manifested by a decrease in lung protein expression of tumor necrosis factor-α and interleukin-1β and mRNA expression of interleukin-6, interferon-γ, nuclear factor-κB, and inducible nitric oxide synthase, with a concurrent increase in interleukin-10 expression. The anti-inflammatory effect of Nar-Dx-NCs was more potent than naringin. Regarding the effect on apoptosis, both naringin and Nar-Dx-NCs significantly reduced Bcl-2 and increased Bax and P53 expressions. Moreover, naringin or Nar-Dx-NCs induced a significant decrease in the expression of the proliferator marker, Ki-67, and the effect of Nar-Dx-NCs was more marked. In conclusion, Nar-Dx-NCs improved naringin's preventive action against DEN/2AAF-induced lung cancer and exerted anticarcinogenic effects by suppressing oxidative stress and inflammation and improving apoptotic signal induction and propagation.

Dyrk2 gene transfer suppresses hepatocarcinogenesis by promoting the degradation of Myc and Hras

Background & Aims

Hepatocellular carcinoma (HCC) is one of the most common cancers worldwide, and has a poor prognosis. However, the molecular mechanisms underlying hepatocarcinogenesis and progression remain unknown. In vitro gain- and loss-of-function analyses in cell lines and xenografts revealed that dual-specificity tyrosine-regulated kinase 2 (DYRK2) influences tumour growth in HCC.

Methods

To investigate the role of Dyrk2 during hepatocarcinogenesis, we developed liver-specific Dyrk2 conditional knockout mice and an in vivo gene delivery system with a hydrodynamic tail vein injection and the Sleeping Beauty transposon. The antitumour effects of Dyrk2 gene transfer were investigated in a murine autologous carcinogenesis model.

Results

Dyrk2 expression was reduced in tumours, and that its downregulation was induced before hepatocarcinogenesis. Dyrk2 gene transfer significantly suppressed carcinogenesis. It also suppresses Myc-induced de-differentiation and metabolic reprogramming, which favours proliferative, and malignant potential by altering gene profiles. Dyrk2 overexpression caused Myc and Hras degradation at the protein level rather than at the mRNA level, and this degradation mechanism was regulated by the proteasome. Immunohistochemical analyses revealed a negative correlation between DYRK2 expression and MYC and longer survival in patients with HCC with high-DYRK2 and low-MYC expressions.

Conclusions

Dyrk2 protects the liver from carcinogenesis by promoting Myc and Hras degradation. Our findings would pave the way for a novel therapeutic approach using DYRK2 gene transfer.

Impact and Implications

Hepatocellular carcinoma (HCC) is one of the most common cancers, with a poor prognosis. Hence, identifying molecules that can become promising targets for therapies is essential to improve mortality. No studies have clarified the association between DYRK2 and carcinogenesis, although DYRK2 is involved in tumour growth in various cancer cells. This is the first study to show that Dyrk2 expression decreases during hepatocarcinogenesis and that Dyrk2 gene transfer is an attractive approach with tumour suppressive activity against HCC by suppressing Myc-mediated de-differentiation and metabolic reprogramming that favours proliferative and malignant potential via Myc and Hras degradation.

Single-Cell Analysis of Primary Liver Cancer in Mouse Models

Primary liver cancer (PLC), consisting mainly of hepatocellular carcinoma and intrahepatic cholangiocarcinoma, is one of the major causes of cancer-related mortality worldwide. The curative therapy for PLC is surgical resection and liver transplantation, but most PLCs are inoperable at diagnosis. Even after surgery, there is a high rate of tumor recurrence. There is an unmet clinical need to discover more effective treatment options for advanced PLCs. Pre-clinical mouse models in PLC research have played a critical role in identifying key oncogenic drivers and signaling pathways in hepatocarcinogenesis. Furthermore, recent advances in single-cell RNA sequencing (scRNA-seq) have provided an unprecedented degree of resolution in such characterization. In this review, we will summarize the recent studies that utilized pre-clinical mouse models with the combination of scRNA-seq to provide an understanding of different aspects of PLC. We will focus particularly on the potentially actionable targets regarding the cellular and molecular components. We anticipate that the findings in mouse models could complement those in patients. With more defined etiological background, mouse models may provide valuable insights.

Immunometabolic factors contributing to obesity-linked hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a major public health concern that is promoted by obesity and associated liver complications. Onset and progression of HCC in obesity is a multifactorial process involving complex interactions between the metabolic and immune system, in which chronic liver damage resulting from metabolic and inflammatory insults trigger carcinogenesis-promoting gene mutations and tumor metabolism. Moreover, cell growth and proliferation of the cancerous cell, after initiation, requires interactions between various immunological and metabolic pathways that provide stress defense of the cancer cell as well as strategic cell death escape mechanisms. The heterogenic nature of HCC in addition to the various metabolic risk factors underlying HCC development have led researchers to focus on examining metabolic pathways that may contribute to HCC development. In obesity-linked HCC, oncogene-induced modifications and metabolic pathways have been identified to support anabolic demands of the growing HCC cells and combat the concomitant cell stress, coinciding with altered utilization of signaling pathways and metabolic fuels involved in glucose metabolism, macromolecule synthesis, stress defense, and redox homeostasis. In this review, we discuss metabolic insults that can underlie the transition from steatosis to steatohepatitis and from steatohepatitis to HCC as well as aberrantly regulated immunometabolic pathways that enable cancer cells to survive and proliferate in the tumor microenvironment. We also discuss therapeutic modalities targeted at HCC prevention and regression. A full understanding of HCC-associated immunometabolic changes in obesity may contribute to clinical treatments that effectively target cancer metabolism.

A monoclonal antibody targeting nonjunctional claudin-1 inhibits fibrosis in patient-derived models by modulating cell plasticity

Tissue fibrosis is a key driver of end-stage organ failure and cancer, overall accounting for up to 45% of deaths in developed countries. There is a large unmet medical need for antifibrotic therapies. Claudin-1 (CLDN1) is a member of the tight junction protein family. Although the role of CLDN1 incorporated in tight junctions is well established, the function of nonjunctional CLDN1 (njCLDN1) is largely unknown. Using highly specific monoclonal antibodies targeting a conformation-dependent epitope of exposed njCLDN1, we show in patient-derived liver three-dimensional fibrosis and human liver chimeric mouse models that CLDN1 is a mediator and target for liver fibrosis. Targeting CLDN1 reverted inflammation-induced hepatocyte profibrogenic signaling and cell fate and suppressed the myofibroblast differentiation of hepatic stellate cells. Safety studies of a fully humanized antibody in nonhuman primates did not reveal any serious adverse events even at high steady-state concentrations. Our results provide preclinical proof of concept for CLDN1-specific monoclonal antibodies for the treatment of advanced liver fibrosis and cancer prevention. Antifibrotic effects in lung and kidney fibrosis models further indicate a role of CLDN1 as a therapeutic target for tissue fibrosis across organs. In conclusion, our data pave the way for further therapeutic exploration of CLDN1-targeting therapies for fibrotic diseases in patients.

A Critical Role of the IL-22-IL-22 Binding Protein Axis in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) ranks among the five most common cancer entities worldwide and leads to hundred-thousands of deaths every year. Despite some groundbreaking therapeutical revelations during the last years, the overall prognosis remains poor. Although the immune system fights malignant transformations with a robust anti-tumor response, certain immune mediators have also been shown to promote cancer development. For example, interleukin (IL)-22 has been associated with HCC progression and worsened prognosis in multiple studies. However, the underlying mechanisms of the pathological role of IL-22-signaling as well as the role of its natural antagonist IL-22 binding protein (IL-22BP) in HCC remain elusive. Here, we corroborate the pathogenic role of IL-22 in HCC by taking advantage of two mouse models. Moreover, we observed a protective role of IL-22BP during liver carcinogenesis. While IL-22 was mainly produced by CD4⁺ T cells in HCC, IL-22BP was abundantly expressed by neutrophils during liver carcinogenesis. Hepatocytes could be identified as a major target of this pathological IL-22-signaling. Moreover, abrogation of IL-22 signaling in hepatocytes in IL22ra1^flox/flox × Alb^Cre+ mice reduced STEAP4 expression-a known oncogene-in HCC in vivo. Likewise, STEAP4 expression correlated with IL22 levels in human HCC samples, but not in healthy liver specimens. In conclusion, these data encourage the development of therapeutical approaches that target the IL-22-IL-22BP axis in HCC.

A researcher's guide to preclinical mouse NASH models

Non-alcoholic fatty liver disease (NAFLD) and its inflammatory form, non-alcoholic steatohepatitis (NASH), have quickly risen to become the most prevalent chronic liver disease in the Western world and are risk factors for the development of hepatocellular carcinoma (HCC). HCC is not only one of the most common cancers but is also highly lethal. Nevertheless, there are currently no clinically approved drugs for NAFLD, and NASH-induced HCC poses a unique metabolic microenvironment that may influence responsiveness to certain treatments. Therefore, there is an urgent need to better understand the pathogenesis of this rampant disease to devise new therapies. In this line, preclinical mouse models are crucial tools to investigate mechanisms as well as novel treatment modalities during the pathogenesis of NASH and subsequent HCC in preparation for human clinical trials. Although, there are numerous genetically induced, diet-induced and toxin-induced models of NASH, not all of these models faithfully phenocopy and mirror the human pathology very well. In this Perspective, we shed some light onto the most widely used mouse models of NASH and highlight some of the key advantages and disadvantages of the various models with an emphasis on 'Western diets', which are increasingly recognized as some of the best models in recapitulating the human NASH pathology and comorbidities.

Adipose stem cells preincubated with theanine exert liver regeneration through increase of stem cell paracrine VEGF and suppression of ROS, pyroptosis as well as autophagy markers in liver damage induced by N-nitrosodiethylamine

AIMS

Liver diseases induce a severe decrease in quality of life. Stem cell based therapy shows therapeutic potential in the treatment of liver injury. Theanine is a unique amino acid found in green tea and could confer beneficial effects on cell protection. This study investigates if protective effect on the liver by stem cells preincubated with theanine is better than that from stem cells without preincubated theanine.

METHODS

We transplanted theanine preincubated adipose-derived stem cells (ADSC) to male Wistar rats with liver dysfunction induced by N-nitrosodiethylamine. The viability, migration and antioxidant capabilities were performed in the ADSC pre-incubated with theanine. Hepatic functional, structural and molecular assays were determined in the animals with or without theanine preincubated ADSC.

KEY FINDINGS

Cell model revealed that ADSC preincubated with green tea theanine (T-ADSC) increased cell capabilities including viability, migration and paracrine secretion. In vivo results indicated that several pathological conditions were observed in rats with liver injury induced by DEN including structural changes and expression of pyroptosis as well as autophagy markers. The above pathological conditions were improved when the rats received both ADSC and T-ADSC treatment. Furthermore, T-ADSC showed better therapeutic effect on rats with liver injury than ADSC due to significant suppression of pyroptosis markers caspase-1 and IL-1β as well as autophagy marker LC3-II accompanied with intensive paracrine VEGF from T-ADSC.

SIGNIFICANCE

Increased paracrine VEGF secretion from T-ADSC plays a crucial role in liver regeneration. A future clinical study may be designed for further verification of these experimental in vivo findings.

Hepatocellular carcinoma chemoprevention by targeting the angiotensin-converting enzyme and EGFR transactivation

Hepatocellular carcinoma (HCC) is a leading cause of death among cirrhotic patients, for which chemopreventive strategies are lacking. Recently, we developed a simple human cell-based system modeling a clinical prognostic liver signature (PLS) predicting liver disease progression and HCC risk. In a previous study, we applied our cell-based system for drug discovery and identified captopril, an approved angiotensin converting enzyme (ACE) inhibitor, as a candidate compound for HCC chemoprevention. Here, we explored ACE as a therapeutic target for HCC chemoprevention. Captopril reduced liver fibrosis and effectively prevented liver disease progression toward HCC development in a diethylnitrosamine (DEN) rat cirrhosis model and a diet-based rat model for nonalcoholic steatohepatitis–induced (NASH-induced) hepatocarcinogenesis. RNA-Seq analysis of cirrhotic rat liver tissues uncovered that captopril suppressed the expression of pathways mediating fibrogenesis, inflammation, and carcinogenesis, including epidermal growth factor receptor (EGFR) signaling. Mechanistic data in liver disease models uncovered a cross-activation of the EGFR pathway by angiotensin. Corroborating the clinical translatability of the approach, captopril significantly reversed the HCC high-risk status of the PLS in liver tissues of patients with advanced fibrosis. Captopril effectively prevents fibrotic liver disease progression toward HCC development in preclinical models and is a generic and safe candidate drug for HCC chemoprevention.

Potential anti-hepatocellular carcinoma properties and mechanisms of action of clerodane diterpenes isolated from Polyalthia longifolia seeds

Diterpenes are secondary metabolites that have attracted much attention due to their potential biological activities including anti-cancer potential. The aim of the current study is to assess the anticancer potential of the six known clerodane diterpenes (1–6) isolated from Polyalthia longifolia seeds and their underlying molecular mechanisms. These compounds were evaluated for their cytotoxicity in vitro by using MTT assays. The “two-phase model” with NDEA and PB ad libitum was used for induction of HCC and sorafenib was used as the standard drug. Prophylactic studies were carried out for compounds 4/6 at both low (5 mg/kg b.w) and high (10 mg/kg b.w) doses. Based on the MTT assay results, the two best compounds, 4 and 6, were selected for in vivo studies. The results showed that treatment with compound 4/6 significantly restored the changes in biochemical parameters and liver morphology observed in (NDEA + PB)-induced HCC rats. Additionally, the docking studies showed that compound 4/6 interacted with several key proteins such as MDM2, TNF-α, FAK, thereby inhibiting these proteins and reversing the negative impacts of NDEA. In conclusion, our results suggested that compounds 4 and 6 are potential therapeutic agents for HCC, mostly due to their ability to control typical cancer pathways.

Early-Life Exposure to Low-Dose Cadmium Accelerates Diethylnitrosamine and Diet-Induced Liver Cancer

Maternal exposure to cadmium causes obesity and metabolic changes in the offspring, including nonalcoholic fatty liver disease-like pathology. However, whether maternal cadmium exposure accelerates liver cancer in the offspring is unknown. This study investigated the impact of early-life exposure to cadmium on the incidence and potential mechanisms of hepatocellular carcinoma (HCC) in offspring subjected to postweaning HCC induction. HCC in C57BL/6J mice was induced by diethylnitrosamine (DEN) injection at weaning, followed by a long-term high-fat choline-deficient (HFCD) diet. Before weaning, liver cadmium levels were significantly higher in mice with early-life cadmium exposure than in those without cadmium exposure. However, by 26 and 29 weeks of age, hepatic cadmium fell to control levels, while a significant decrease was observed in copper and iron in the liver. Both male and female cadmium-exposed mice showed increased body weight compared to non-cadmium-treated mice. For females, early-life cadmium exposure also worsened insulin intolerance but did not significantly promote DEN/HFCD diet-induced liver tumors. In contrast, in male mice, early-life cadmium exposure enhanced liver cancer induction by DEN/HFCD with high incidence and larger liver tumors. The liver peritumor tissue of early-life cadmium-exposed mice exhibited greater inflammation and disruption of fatty acid metabolism, accompanied by higher malondialdehyde and lower esterified triglyceride levels compared to mice without cadmium exposure. These findings suggest that early-life exposure to low-dose cadmium accelerates liver cancer development induced by a DEN/HFCD in male mice, probably due to chronic lipotoxicity and inflammation caused by increased uptake but decreased consumption of fatty acids.

Models of nonalcoholic steatohepatitis potentiated by chemical inducers leading to hepatocellular carcinoma

Hepatocellular carcinoma (HCC), the most common primary liver cancer, arises after a long period of exposure to etiological factors. Nonalcoholic steatohepatitis (NASH) is ranked as the main risk factor for developing HCC; hence, experimental models of NASH leading to HCC have become key tools both to investigate the molecular mechanisms underlying the pathophysiology and to evaluate new putative drugs for treating chronic liver diseases in humans. Animal models of NASH induced by a high-fat diet (HFD) plus chemical inducers, such as the NASH-HCC (STAM), high-fat diet/diethylnitrosamine (HFD/DEN), choline-deficient high-fat diet/DEN (CDHFD/DEN), and Western diet/carbon tetrachloride (WD/CCl₄) models, are promising because they exacerbate liver damage and significantly shorten the experimental time. In this review, we critically summarize and discuss the ability of these models to recapitulate the liver alterations that precede and lead to HCC progression, as well as the impact of the diet in promoting liver injury progression. We also emphasize the strengths and weaknesses of the models' ability to closely mimic the stages of liver injury development that occur in humans. Based on the molecular mechanisms induced by the currently available NASH models leading to HCC, we argue that although several NASH models have importantly contributed to describing the disease chronology, the progress in emulating the progression from NASH to HCC has been partial. Thus, the development of novel NASH/HCC models remains an unmet need.

Genetics, Immunity and Nutrition Boost the Switching from NASH to HCC

Nonalcoholic fatty liver disease (NAFLD) is the leading contributor to the global burden of chronic liver diseases. The phenotypic umbrella of NAFLD spans from simple and reversible steatosis to nonalcoholic steatohepatitis (NASH), which may worsen into cirrhosis and hepatocellular carcinoma (HCC). Notwithstanding, HCC may develop also in the absence of advanced fibrosis, causing a delayed time in diagnosis as a consequence of the lack of HCC screening in these patients. The precise event cascade that may precipitate NASH into HCC is intricate and it entails diverse triggers, encompassing exaggerated immune response, endoplasmic reticulum (ER) and oxidative stress, organelle derangement and DNA aberrancies. All these events may be accelerated by both genetic and environmental factors. On one side, common and rare inherited variations that affect hepatic lipid remodeling, immune microenvironment and cell survival may boost the switching from steatohepatitis to liver cancer, on the other, diet-induced dysbiosis as well as nutritional and behavioral habits may furtherly precipitate tumor onset. Therefore, dietary and lifestyle interventions aimed to restore patients' health contribute to counteract NASH progression towards HCC. Even more, the combination of therapeutic strategies with dietary advice may maximize benefits, with the pursuit to improve liver function and prolong survival.

Activation of FXR modulates SOCS3/Jak2/STAT3 signaling axis in a NASH-dependent hepatocellular carcinoma animal model

Despite the recent substantial progress in the treatment of hepatocellular carcinoma (HCC) from viral etiology, non-alcoholic steatohepatitis (NASH) is on a trajectory to become the fastest growing indication for HCC-related liver transplantation. The Farnesoid X receptor (FXR) is a member of the nuclear receptor superfamily with multifaceted roles in several metabolic disorders, particularly NASH. Its role as a tumor suppressor was also highlighted. Herein, we investigated the effect of obeticholic acid (OCA), as an FXR agonist, on NASH-associated HCC (NASH-HCC) animal model induced by diethylnitrosamine and high fat choline-deficient diet, exploring the potential impact on the suppressor of cytokine signaling 3 (SOCS3)/Janus kinase 2 (Jak2)/signal transducer and activator of transcription 3 (STAT3) pathway. Results indicated that OCA treatment upregulated FXR and its key mediator, small heterodimer partner (SHP), with remarkable amelioration in the dysplastic foci observed in the NASH-HCC group. This was paralleled with noticeable downregulation of alpha fetoprotein along with reduction in interferon gamma and transforming growth factor beta-1 hepatic levels besides caspase-3 and p53 upregulation. Moreover, sirtuin-1 (SIRT-1), a key regulator of FXR that controls the regenerative response of the liver, was elevated following OCA treatment. Modulation in the SOCS3/Jak2/STAT3 signaling axis was also reported. In conclusion, OCA attenuated the development and progression of NASH-dependent HCC possibly by interfering with SOCS3/Jak2/STAT3 pathway suggesting the potential use of FXR activators in NASH-related disorders, even at later stages of the disease, to impede its progression to the more deteriorating condition of HCC.

Characterizing the mechanism behind the progression of NAFLD to hepatocellular carcinoma

Hepatocellular carcinoma (HCC) developed in non-alcoholic fatty liver disease (NAFLD) individuals presents substantial clinical and biological characteristics, which remain to be elucidated. Its occurrence in noncirrhotic patients raises issues regarding surveillance strategies, which cannot be considered as cost-effective given the high prevalence of obesity and metabolic syndrome, and furthermore delineates specific oncogenic process that could be targeted in the setting of primary or secondary prevention. In this context, the identification of a genetic heterogeneity modulating HCC risk as well as specific biological pathways have been made possible through genome-wide association studies, development of animal models and in-depth analyses of human samples at the pathological and genomic levels. These advances must be confirmed and pursued to pave the way for personalized management of NAFLD-related HCC.

Non-Alcoholic Steatohepatitis: A Review of Its Mechanism, Models and Medical Treatments

Non-alcoholic steatohepatitis (NASH) develops from non-alcoholic fatty liver disease (NAFLD). Currently, around 25% of the population is estimated to have NAFLD, and 25% of NAFLD patients are estimated to have NASH. NASH is typically characterized by liver steatosis inflammation, and fibrosis driven by metabolic disruptions such as obesity, diabetes, and dyslipidemia. NASH patients with significant fibrosis have increased risk of developing cirrhosis and liver failure. Currently, NASH is the second leading cause for liver transplant in the United States. More importantly, the risk of developing hepatocellular carcinoma from NASH has also been highlighted in recent studies. Patients may have NAFLD for years before progressing into NASH. Although the pathogenesis of NASH is not completely understood, the current “multiple-hits” hypothesis suggests that in addition to fat accumulation, elevated oxidative and ER stress may also drive liver inflammation and fibrosis. The development of clinically relevant animal models and pharmacological treatments for NASH have been hampered by the limited understanding of the disease mechanism and a lack of sensitive, non-invasive diagnostic tools. Currently, most pre-clinical animal models are divided into three main groups which includes: genetic models, diet-induced, and toxin + diet-induced animal models. Although dietary models mimic the natural course of NASH in humans, the models often only induce mild liver injury. Many genetic and toxin + diet-induced models rapidly induce the development of metabolic disruption and serious liver injury, but not without their own shortcomings. This review provides an overview of the “multiple-hits” hypothesis and an evaluation of the currently existing animal models of NASH. This review also provides an update on the available interventions for managing NASH as well as pharmacological agents that are currently undergoing clinical trials for the treatment of NASH.

Diet-dependent gut microbiota impacts on adult neurogenesis through mitochondrial stress modulation

The influence of dietary factors on brain health and mental function is becoming increasingly recognized. Similarly, mounting evidence supports a role for gut microbiota in modulating central nervous system function and behaviour. Still, the molecular mechanisms responsible for the impact of diet and associated microbiome in adult neurodegeneration are still largely unclear. In this study, we aimed to investigate whether and how changes in diet-associated microbiome and its metabolites impact on adult neurogenesis. Mice were fed a high-fat, choline-deficient diet, developing obesity and several features of the metabolic syndrome, including non-alcoholic steatohepatitis. Strikingly, our results showed, for the first time, that animals fed with this specific diet display premature increased neurogenesis, possibly exhausting the available neural stem cell pool for long-term neurogenesis processes. The high-fat, choline-deficient diet further induced neuroinflammation, oxidative stress, synaptic loss and cell death in different regions of the brain. Notably, this diet-favoured gut dysbiosis in the small intestine and cecum, up-regulating metabolic pathways of short-chain fatty acids, such as propionate and butyrate and significantly increasing propionate levels in the liver. By dissecting the effect of these two specific short-chain fatty acids in vitro, we were able to show that propionate and butyrate enhance mitochondrial biogenesis and promote early neurogenic differentiation of neural stem cells through reactive oxygen species- and extracellular signal-regulated kinases 1/2-dependent mechanism. More importantly, neurogenic niches of high-fat, choline-deficient-fed mice showed increased expression of mitochondrial biogenesis markers, and decreased mitochondrial reactive oxygen species scavengers, corroborating the involvement of this mitochondrial stress-dependent pathway in mediating changes of adult neurogenesis by diet. Altogether, our results highlight a mitochondria-dependent pathway as a novel mediator of the gut microbiota–brain axis upon dietary influences.

Diethylnitrosamine-induced liver tumorigenesis in mice

Hepatocellular carcinoma (HCC) is the fifth most common cancer worldwide and the third leading cause of cancer related mortality with a 10 year survival rate of merely 22-35%. Tumorigenesis frequently occurs in patients with chronic liver disease where continued liver cell damage, compensatory proliferation and inflammation provide the basis for tumor initiation, promotion and progression. Animal models of HCC are particularly useful to better understand molecular events underlying liver tumorigenesis. To this end, chemical carcinogenesis protocols based on the injection of genotoxic compounds such as diethylnitrosamine (DEN) are widely used to model liver tumorigenesis in rodents. DEN injection into 2 week old mice is sufficient to cause liver tumorigenesis after 8-10 months. When injected into older mice, DEN has to be combined with administration of tumor promoting agents such as phenobarbital or feeding high fat diet. Such protocols allow to dissect the different steps of tumor formation (i.e., tumor initiation and promotion) experimentally and to model liver pathologies in mice which frequently lead to HCC in human patients such as non-alcoholic fatty liver disease. Here, we review several established chemical carcinogenesis protocols based on DEN injection into mice and discuss their advantages as well as potential limitations.

Gut Dysbiosis and Increased Intestinal Permeability Drive microRNAs, NLRP-3 Inflammasome and Liver Fibrosis in a Nutritional Model of Non-Alcoholic Steatohepatitis in Adult Male Sprague Dawley Rats

Background/Aim

The interactions between the gut and liver have been described in the progression of non-alcoholic steatohepatitis (NASH). The aim of this study was to develop an experimental nutritional model of NASH simulating metabolic changes occurring in humans.

Materials and Methods

Adult male Sprague Dawley rats were randomized into two groups: controls (standard diet) and intervention (high-fat and choline-deficient diet) for 16 weeks, each experimental group with 10 animals. Biochemical analysis, hepatic lipid content, microRNAs, inflammatory, gut permeability markers and gut microbiota were measured.

Results

Animals in the intervention group showed significantly higher delta Lee index (p=0.017), abdominal circumference (p<0.001), abdominal adipose tissue (p<0.001) and fresh liver weight (p<0.001), as well as higher serum levels of alanine aminotransferase (p=0.010), glucose (p=0.013), total cholesterol (p=0.033), LDL cholesterol (p=0.011), and triglycerides (p=0.011), and lower HDL cholesterol (p=0.006) compared to the control group. Higher TLR4 (p=0.041), TLR9 (p=0.033), MyD88 (p=0.001), Casp1 (p<0.001), NLPR3 (p=0.019), liver inflammation index interleukin (IL)-1β/IL10 (p<0.001), IL6/IL10 (p=0.002) and TNFα/IL10 (p=0.001) were observed in the intervention group, and also lower permeability markers Ocln (p=0.003) and F11r (p=0.041). Gene expression of miR-122 increased (p=0.041) and miR-145 (p=0.010) decreased in the intervention group. Liver steatosis, inflammation and fibrosis, along with collagen fiber deposition increment (p<0.001), were seen in the intervention group. Regarding gut microbiota, Bray-Curtis dissimilarity index and number of operational taxonomic units were significantly different (p<0.001) between the groups. Composition of the gut microbiota showed a significant correlation with histopathological score of NAFLD (r=0.694) and index IL-1β/IL-10 (r=0.522).

Conclusion

This experimental model mimicking human NASH demonstrated gut and liver interaction, with gut microbiota and intestinal permeability changes occurring in parallel with systemic and liver inflammation, miRNAs regulation and liver tissue damage.

The American lifestyle-induced obesity syndrome diet in male and female rodents recapitulates the clinical and transcriptomic features of nonalcoholic fatty liver disease and nonalcoholic steatohepatitis

The pathogenesis of nonalcoholic fatty liver disease (NAFLD) and the progression to nonalcoholic steatohepatitis (NASH) and increased risk of hepatocellular carcinoma remain poorly understood. Additionally, there is increasing recognition of the extrahepatic manifestations associated with NAFLD and NASH. We demonstrate that intervention with the American lifestyle-induced obesity syndrome (ALIOS) diet in male and female mice recapitulates many of the clinical and transcriptomic features of human NAFLD and NASH. Male and female C57BL/6N mice were fed either normal chow (NC) or ALIOS from 11 to 52 wk and underwent comprehensive metabolic analysis throughout the duration of the study. From 26 wk, ALIOS-fed mice developed features of hepatic steatosis, inflammation, and fibrosis. ALIOS-fed mice also had an increased incidence of hepatic tumors at 52 wk compared with those fed NC. Hepatic transcriptomic analysis revealed alterations in multiple genes associated with inflammation and tissue repair in ALIOS-fed mice. Ingenuity Pathway Analysis confirmed dysregulation of metabolic pathways as well as those associated with liver disease and cancer. In parallel the development of a robust hepatic phenotype, ALIOS-fed mice displayed many of the extrahepatic manifestations of NAFLD, including hyperlipidemia, increased fat mass, sarcopenia, and insulin resistance. The ALIOS diet in mice recapitulates many of the clinical features of NAFLD and, therefore, represents a robust and reproducible model for investigating the pathogenesis of NAFLD and its progression.NEW & NOTEWORTHY Nonalcoholic fatty liver disease (NAFLD) affects 30% of the general population and can progress to nonalcoholic steatohepatitis (NASH) and potentially hepatocellular carcinoma. Preclinical models rely on mouse models that often display hepatic characteristics of NAFLD but rarely progress to NASH and seldom depict the multisystem effects of the disease. We have conducted comprehensive metabolic analysis of both male and female mice consuming a Western diet of trans fats and sugar, focusing on both their hepatic phenotype and extrahepatic manifestations.

Fatty changes associated with N-Nitrosodiethylamine (DEN) induced hepatocellular carcinoma: a role of sonic hedgehog signaling pathway

Backgrounds and Aims: Hepatocellular Carcinoma (HCC) is the leading cause of cancer-related mortality across the world. Non-viral etiological factors including obesity and metabolic syndrome have now become prevalent cause of hepatocellular carcinoma. Sonic Hedgehog (SHH) pathway is activated in hepatocellular carcinoma but its role in regulation of lipogenic molecules during the hepatocarcinogenesis is not known. The aim of present study is to explore the role of SHH pathway in fatty changes associated with hepatocarcinogenesis at different stages and to further correlate the expression of SHH with lipogenic pathways.

Results: Our results demonstrated significant increase in lipidosis and fibrosis in DEN+CCl4 treated animals. It was simultaneously associated with the enhanced expression level of SHH, E2F1, adiponectin, and lipogenic molecules in DEN+CCl4 treated animals. These results were also corroborated with the similar findings in higher stage patients’ biospecimens.

Methods: N-Nitrosodiethylamine (DEN) and Carbon TetraChloride (CCl4) induced hepatocellular acrcinoma model in male Wistar rats were established to study the expression level of SHH pathway and associated fatty changes during different stages of hepatocarcinogenesis. The expression levels of SHH, E2F1, and lipogenic molecules were checked at different stages of hepatocellular carcinoma. These results were further compared with biospecimens of hepatocellular carcinoma patients of different stages.

Conclusions: Our results revealed an unknown aspect of SHH pathway in hepatocarcinogenesis via its control over lipogenesis. It gives insight into the lipogenic properties of DEN+CCl4 induced rodent hepatocarcinogenesis model and how SHH pathway operate to arbitrate this response.

Low-Dose Sorafenib Acts as a Mitochondrial Uncoupler and Ameliorates Nonalcoholic Steatohepatitis

Nonalcoholic steatohepatitis (NASH) is becoming one of the leading causes of hepatocellular carcinoma (HCC). Sorafenib is the only first-line therapy for advanced HCC despite its serious adverse effects. Here, we report that at an equivalent of approximately one-tenth the clinical dose for HCC, sorafenib treatment effectively prevents the progression of NASH in both mice and monkeys without any observed significant adverse events. Mechanistically, sorafenib's benefit in NASH is independent of its canonical kinase targets in HCC, but involves the induction of mild mitochondrial uncoupling and subsequent activation of AMP-activated protein kinase (AMPK). Collectively, our findings demonstrate a previously unappreciated therapeutic effect and signaling mechanism of low-dose sorafenib treatment in NASH. We envision that this new therapeutic strategy for NASH has the potential to translate into a beneficial anti-NASH therapy with fewer adverse events than is observed in the drug's current use in HCC.

Dietary Choline Supplementation Attenuates High-Fat-Diet-Induced Hepatocellular Carcinoma in Mice

BACKGROUND

Hepatocellular carcinoma (HCC) is the third most common cause of cancer-related death in the world. Choline deficiency has been well studied in the context of liver disease; however, less is known about the effects of choline supplementation in HCC.

OBJECTIVE

The objective of this study was to test whether choline supplementation could influence the progression of HCC in a high-fat-diet (HFD)-driven mouse model.

METHODS

Four-day-old male C57BL/6J mice were treated with the chemical carcinogen, 7,12-dimethylbenz[a]anthracene, and were randomly assigned at weaning to a cohort fed an HFD (60% kcal fat) or an HFD with supplemental choline (60% kcal fat, 1.2% choline; HFD+C) for 30 wk. Blood was isolated at 15 and 30 wk to measure immune cells by flow cytometry, and glucose-tolerance tests were performed 2 wk prior to killing. Overall tumor burden was quantified, hepatic lipids were measured enzymatically, and phosphatidylcholine species were measured by targeted MS methods. Gene expression and mitochondrial DNA were quantified by quantitative PCR.

RESULTS

HFD+C mice exhibited a 50-90% increase in both circulating choline and betaine concentrations in the fed state (P ≤ 0.05). Choline supplementation resulted in a 55% decrease in total tumor numbers, a 67% decrease in tumor surface area, and a 50% decrease in hepatic steatosis after 30 wk of diet (P ≤ 0.05). Choline supplementation increased the abundance of mitochondria and the relative expression of β-oxidation genes by 21% and ∼75-100%, respectively, in the liver. HFD+C attenuated circulating myeloid-derived suppressor cells at 15 wk of feeding (P ≤ 0.05).

CONCLUSIONS

Choline supplementation attenuated HFD-induced HCC and hepatic steatosis in male C57BL/6J mice. These results suggest a therapeutic benefit of choline supplementation in blunting HCC progression.

Hepatocellular carcinoma in the context of non-alcoholic steatohepatitis (NASH): recent advances in the pathogenic mechanisms

Hepatocellular carcinoma (HCC) is the most common type of liver cancer. HCC is particularly aggressive and is one of the leading causes of cancer mortality. In recent decades, the epidemiological landscape of HCC has undergone significant changes. While chronic viral hepatitis and excessive alcohol consumption have long been identified as the main risk factors for HCC, non-alcoholic steatohepatitis (NASH), paralleling the worldwide epidemic of obesity and type 2 diabetes, has become a growing cause of HCC in the US and Europe. Here, we review the recent advances in epidemiological, genetic, epigenetic and pathogenic mechanisms as well as experimental mouse models that have improved the understanding of NASH progression toward HCC. We also discuss the clinical management of patients with NASH-related HCC and possible therapeutic approaches.

Risk factors for hepatocellular carcinoma (HCC) in the northeast of the United States: results of a case-control study

PURPOSE

HCC incidence has been continuously rising in the US for the past 30 years. To understand the increase in HCC risk, we conducted a case-control study in Connecticut, New Jersey and part of New York City.

METHODS

Through rapid case ascertainment and random digit dialing, we recruited 673 incident HCC patients and 1,166 controls. Information on demographic and anthropometric characteristics, lifestyle factors, medical and family cancer histories, were ascertained through telephone interviews using a structured questionnaire. Saliva specimens were collected for testing hepatitis C virus (HCV) antibodies. Unconditional logistic regression models were utilized to calculate odds ratio (OR) and 95% confidence interval (CI) to determine HCC associations with risk factors.

RESULTS

The study confirmed that HCV infection and obesity were important risk factors for HCC, ORs 110 (95% CI 59.2-204) and 2.13 (95% CI 1.52-3.00), respectively. High BMI and HCV infection had synergy in association with elevated HCC risk. Patients both obese and infected with HCV had HCC detected on average nearly 10 years earlier than those with neither factor. Diabetes, cigarette smoking and heavy alcohol intake were all associated with increased risk of HCC, whereas aspirin and other NSAID use were associated with reduced risk. HCC cases tended to attain less education, with lower household incomes, unmarried, and to have had more sexual partners than the controls.

CONCLUSIONS

Individuals at risk of HCC in the US comprise a unique population with low socioeconomic status and unhealthy lifestyle choices. Given the multifactorial nature, a comprehensive approach is needed in HCC prevention.

An interaction between MKL1, BRG1, and C/EBPβ mediates palmitate induced CRP transcription in hepatocytes

Non-alcoholic steatohepatitis (NASH) is one of the most predominant disorders in metabolic syndrome. Induction of pro-inflammatory mediators in hepatocytes exposed to free fatty acids represents a hallmark event during NASH pathogenesis. C-reactive protein (CRP) is a prototypical pro-inflammatory mediator. In the present study, we investigated the mechanism by which megakaryocytic leukemia 1 (MKL1) mediates palmitate (PA) induced CRP transcription in hepatocytes. We report that over-expression of MKL1, but not MKL2, activated the CRP promoter whereas depletion or inhibition of MKL1 repressed the CRP promoter. MKL1 potentiated the induction of the CRP promoter activity by PA treatment. Importantly, MKL1 knockdown by siRNA or pharmaceutical inhibition by CCG-1423 attenuated the induction of endogenous CRP expression in hepatocytes. Similarly, primary hepatocytes isolated from wild type (WT) mice produced more CRP than those isolated from MKL1 deficient (KO) mice when stimulated with PA. Mechanistically, the sequence-specific transcription factor CCAAT-enhancer-binding protein (C/EBPβ) interacted with MKL1 and recruited MKL1 to activate CRP transcription. Reciprocally, MKL1 modulated C/EBPβ activity by recruiting the chromatin remodeling protein BRG1 to the CRP promoter to alter histone modifications. In conclusion, our data delineate a novel epigenetic mechanism underlying augmented hepatic inflammation during NASH pathogenesis.

Deranged hepatocyte intracellular Ca2+ homeostasis and the progression of non-alcoholic fatty liver disease to hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the second leading cause of cancer-related deaths in men, and the sixth in women. Non-alcoholic fatty liver disease (NAFLD) is now one of the major risk factors for HCC. NAFLD, which involves the accumulation of excess lipid in cytoplasmic lipid droplets in hepatocytes, can progress to non-alcoholic steatosis, fibrosis, and HCC. Changes in intracellular Ca²⁺ constitute important signaling pathways for the regulation of lipid and carbohydrate metabolism in normal hepatocytes. Recent studies of steatotic hepatocytes have identified lipid-induced changes in intracellular Ca²⁺, and have provided evidence that altered Ca²⁺ signaling exacerbates lipid accumulation and may promote HCC. The aims of this review are to summarise current knowledge of the lipid-induced changes in hepatocyte Ca²⁺ homeostasis, to comment on the mechanisms involved, and discuss the pathways leading from altered Ca²⁺ homeostasis to enhanced lipid accumulation and the potential promotion of HCC. In steatotic hepatocytes, lipid inhibits store-operated Ca²⁺ entry and SERCA2b, and activates Ca²⁺ efflux from the endoplasmic reticulum (ER) and its transfer to mitochondria. These changes are associated with changes in Ca²⁺ concentrations in the ER (decreased), cytoplasmic space (increased) and mitochondria (likely increased). They lead to: inhibition of lipolysis, lipid autophagy, lipid oxidation, and lipid secretion; activation of lipogenesis; increased lipid; ER stress, generation of reactive oxygen species (ROS), activation of Ca²⁺/calmodulin-dependent kinases and activation of transcription factor Nrf2. These all can potentially mediate the transition of NAFLD to HCC. It is concluded that lipid-induced changes in hepatocyte Ca²⁺ homeostasis are important in the initiation and progression of HCC. Further research is desirable to better understand the cause and effect relationships, the time courses and mechanisms involved, and the potential of Ca²⁺ transporters, channels, and binding proteins as targets for pharmacological intervention.

Preclinical Models for Studying NASH-Driven HCC: How Useful Are They?

Hepatocellular carcinoma (HCC) is one of the most fatal and fastest-growing cancers. Recently, non-alcoholic steatohepatitis (NASH) has been recognized as a major HCC catalyst. However, it is difficult to decipher the molecular mechanisms underlying the pathogenesis of NASH and understand how it progresses to HCC by studying humans. Progress in this field depends on the availability of reliable preclinical models amenable to genetic and functional analyses and exhibiting robust NASH-to-HCC progression. Although numerous mouse models of NASH have been described, many do not faithfully mimic the human disease and few reliably progress to HCC. Here, we review current literature on the molecular etiology of NASH-related HCC and critically evaluate existing mouse models and their suitability for studying this malignancy. We also compare human transcriptomic and histopathological profiles with data from MUP-uPA mice, a reliable model of NASH-driven HCC that has been useful for evaluation of HCC-targeting immunotherapies.

Animal models for hepatocellular carcinoma

Hepatocellular carcinoma (HCC) represents ~90% of all cases of primary liver cancer and occurs predominantly in patients with underlying chronic liver disease and cirrhosis. Establishing appropriate animal models for HCC is required for basic and translational studies, especially the models that can recapitulate one of the human disease settings. Current animal models can be categorized as chemically-induced, genetically-engineered, xenograft, or a combination of these with each other or with a metabolic insult. A single approach to resemble human HCC in animals is not sufficient. Combining pathogenic insults in animal models may more realistically recapitulate the multiple etiologic agents occurring in humans. Combining chemical injury with metabolic disorder or alcohol consumption in mice reduces the time taken to hepatocarcinogenesis. Genetically-engineering weak activation of HCC-promoting pathways combined with disease-specific injury models will possibly mimic the pathophysiology of human HCC in distinct clinical settings.

Multiple liver insults synergize to accelerate experimental hepatocellular carcinoma

The urgent unmet need for hepatocellular carcinoma (HCC) therapies is addressed here by characterising a novel mouse model of HCC in the context of ongoing liver damage and overnutrition. Male C57Bl/6J mice were treated with diethylnitrosamine (DEN) and thioacetamide (TAA), and some were provided with an atherogenic high fat diet (HFD). Inflammation, steatosis, fibrosis, 87 genes, liver lesions and intratumoural leukocyte subsets were quantified up to 24 weeks of age. Adding HFD to DEN/TAA increased fibrosis, steatosis and inflammation, and the incidence of both HCC and non-HCC dysplastic lesions. All lesions contained α-SMA positive fibroblasts. Macrophage marker F4/80 was not significantly different between treatment groups, but the macrophage-associated genes Arg-1 and Cd47 were differentially expressed. Fibrosis, cancer and cell death associated genes were upregulated in DEN/TAA/HFD livers. Fewer Kupffer cells and plasmacytoid dendritic cells were in tumours compared to control liver. In conclusion, combining a hepatotoxin with an atherogenic diet produced more intrahepatic tumours, dysplastic lesions and fibrosis compared to hepatotoxin alone. This new HCC model provides a relatively rapid means of examining primary HCC and potential therapies in the context of multiple hepatotoxins including those derived from overnutrition.

Supervised learning reveals circulating biomarker levels diagnostic of hepatocellular carcinoma in a clinically relevant model of non-alcoholic steatohepatitis; An OAD to NASH

Although cirrhosis is a key risk factor for the development of hepatocellular carcinoma (HCC), mounting evidence indicates that in a subset of patients presenting with non-alcoholic steatohepatitis (NASH) HCC manifests in the absence of cirrhosis. Given the sheer size of the ongoing non-alcoholic fatty liver disease (NAFLD) epidemic and the dismal prognosis associated with late-stage primary liver cancer there is an urgent need for HCC surveillance in the NASH population. Using serum levels of HCC biomarkers as vectors and biopsy-proven HCC or no HCC as outputs / binary classifier, a supervised learning campaign was undertaken to develop a minimally invasive technique for making a diagnosis of HCC in a clinically relevant model of NASH. Adult mice randomized to control diet or a fast food diet (FFD) were followed for up to 14 mo and serum level of a panel of HCC-relevant biomarkers was compared with liver biopsies at 3 and 14 mo. Both NAFLD Activity Score (NAS) and hepatic hydroxyproline content were elevated at 3 and 14 mo on FFD. Picrosirius red staining of liver sections revealed a filigree pattern of fibrillar collagen deposition with no cirrhosis at 14 mo on FFD. Nevertheless, 46% of animals bore one or more tumors on their livers confirmed as HCC in hematoxylin-eosin-stained liver sections. In this training set, receiver operating characteristic (ROC) curves analysis for serum levels of the HCC biomarkers osteopontin (OPN), alpha-fetoprotein (AFP) and Dickkopf-1 (DKK1) returned concordance-statistic/area under ROC curve of ≥ 0.89. Serum levels of OPN (threshold, 218 ng/mL; sensitivity, 82%; specificity, 86%), AFP (136 ng/mL; 91%; 97%) and DKK1 (2.4 ng/mL; 82%; 81%) diagnostic for HCC were confirmed in a test set comprising mice on control diet or FFD and mice subjected to hepatic ischemia-reperfusion injury. These data suggest that levels of circulating OPN, AFP and DKK1 can be used to make a diagnosis of HCC in a clinically relevant model of NASH.

Animal models of NAFLD from the pathologist's point of view

Fatty liver disease is a multifactorial world-wide health problem resulting from a complex interplay between liver, adipose tissue and intestine and initiated by alcohol abuse, overeating, various types of intoxication, adverse drug reactions and genetic or acquired metabolic defects. Depending on etiology fatty liver disease is commonly categorized as alcoholic or non-alcoholic. Both types may progress from simple steatosis to the necro-inflammatory lesion of alcoholic (ASH) and non-alcoholic steatohepatitis (NASH), respectively, and finally to cirrhosis and hepatocellular carcinoma. Animal models are helpful to clarify aspects of pathogenesis and progression. Generally, they are classified as nutritional (dietary), toxin-induced and genetic, respectively, or represent a combination of these factors. Numerous reviews are dealing with NASH animal models designed to imitate as closely as possible the metabolic situation associated with human disease. This review focuses on currently used mouse models of NASH with particular emphasis on liver morphology. Despite metabolic similarities most models (except those with chemically or genetically induced porphyria or keratin 18-deficiency) fail to develop the morphologic key features of NASH, namely hepatocyte ballooning and formation of histologically and immunohistochemically well-defined Mallory-Denk-Bodies (MDBs). Although MDBs are not universally detectable in ballooned hepatocytes in NASH their experimental reproduction and analysis may, however, significantly contribute to our understanding of important pathogenic aspects of NASH despite the obvious differences in etiology.

Adiponectin deficiency contributes to the development and progression of benign prostatic hyperplasia in obesity

The incidence of benign prostatic hyperplasia (BPH) is increasing among obese individuals, but few studies have fully explained the underlying mechanisms. We aimed to elucidate the relationship between obesity and BPH. Herein, we show that in prostatic epithelial and stromal cells, adiponectin exerts multifunctional effects including anti-proliferation, blocking of G1/S-phase progression and the promotion of apoptosis via inhibiting the MEK-ERK-p90RSK axis. Furthermore, we found that a high-fat diet (HFD) led to adiponectin deficiency and microscopic BPH in a mouse model of obesity. And an adiponectin supplement protected the obese mice from microscopic BPH. The present study provides evidence that adiponectin is a protective regulator in the development and progression of BPH and that adiponectin deficiency causally links BPH with obesity.

Hepatic inflammation-fibrosis-cancer axis in the rat hepatocellular carcinoma induced by diethylnitrosamine

PURPOSE

Hepatocellular carcinoma (HCC) cases are closely associated with chronic inflammation and fibrosis which is known as hepatic inflammation-fibrosis-cancer (IFC) axis. The aim of this study is to elucidate the development characteristics of the rat HCC model based on IFC axis.

METHODS

The diethylnitrosamine (DEN)-induced rat HCC, which presents a stepwise histopathological progression that is similar to human HCC, was used to analyze the features of the different stages (inflammation, fibrosis, cancer). Rats were injected DEN at a dose of 30 mg/kg body weight twice a week for 11 weeks and the animals were observed until week 20. Time series sera and organ samples from the DEN animal model were collected to evaluate the dynamic changes.

RESULTS

It was found that serum biochemical indicators (AST, ALT, ALP, TP, T-BIL, IL-6, TNF-α) from DEN-treated group were higher than that from control group. Fibrosis-related index in serum and live tissue were increased, respectively, from week 4 after DEN treatment. The expression of TGF-β1 and α-SMA in DEN-treated group was higher than that in control group. JAK2/STAT3 signaling was significantly up-regulated in DEN-treated group compared to that in control group. The histological examination confirmed that the hepatocarcinogenesis model was successfully established, and 100% of the animals in the DEN-exposed group developed liver tumors at 20 weeks. According to the pathological changes, the model characterized resulted in three stages: the inflammation stage (week 2-6), the fibrosis stage (week 8-12), and the HCC stage (week 14-20).

CONCLUSIONS

The results suggested that the HCC development was associated with IFC axis. The serial progression of hepatocarcinogenesis was according to the sequence of hepatic inflammation, fibrosis and then hepatic tumor.