Experimental models of hepatocellular carcinoma

TET2-mediated tumor cGAS triggers endothelial STING activation to regulate vasculature remodeling and anti-tumor immunity in liver cancer

Induction of tumor vascular normalization is a crucial measure to enhance immunotherapy efficacy. cGAS-STING pathway is vital for anti-tumor immunity, but its role in tumor vasculature is unclear. Herein, using preclinical liver cancer models in Cgas/Sting-deficient male mice, we report that the interdependence between tumor cGAS and host STING mediates vascular normalization and anti-tumor immune response. Mechanistically, TET2 mediated IL-2/STAT5A signaling epigenetically upregulates tumor cGAS expression and produces cGAMP. Subsequently, cGAMP is transported via LRRC8C channels to activate STING in endothelial cells, enhancing recruitment and transendothelial migration of lymphocytes. In vivo studies in male mice also reveal that administration of vitamin C, a promising anti-cancer agent, stimulates TET2 activity, induces tumor vascular normalization and enhances the efficacy of anti-PD-L1 therapy alone or in combination with IL-2. Our findings elucidate a crosstalk between tumor and vascular endothelial cells in the tumor immune microenvironment, providing strategies to enhance the efficacy of combinational immunotherapy for liver cancer.

Hydrodynamic Transfection of Hepatocytes for the Study of Hepatocellular Carcinogenesis

Hydrodynamic tail vein injection (HTVi), also called hydrodynamic gene transfer (HGT), is attracting increasing interest for modeling hepatic carcinogenesis. This highly versatile approach reproducibly provides efficient in vivo transfection of hepatocytes with naked DNA. Here, we give an in-depth description of the injection procedure, which is key for the success of the method. HTVi requires the injection of a large volume of a solution containing plasmids into the tail vein of the mouse. The transient right heart overload created by the injection forces the blood to flow back into the hepatic veins, enlarging the endothelial fenestrae and permeabilizing a fraction of hepatocytes for a few seconds. This results in the uptake of plasmids by the permeabilized hepatocytes, giving rise to their in vivo transfection. Including the Sleeping Beauty transposon system among the injected plasmids leads to the stable transfection of a subset of hepatocytes. HTVi is a powerful technique which enables numerous applications in liver cancer biology, such as a study of oncogene cooperation, of tumor heterogeneity, and interaction with the tumor microenvironment.

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.

Advanced therapeutics avenues in hepatocellular carcinoma: a novel paradigm

Hepatocellular carcinoma (HCC) is the most frequent type of primary liver cancer, and it poses a significant risk to patients health and longevity due to its high morbidity and fatality rates. Surgical ablation, radiotherapy, chemotherapy, and, most recently, immunotherapy have all been investigated for HCC, but none have yielded the desired outcomes. Several unique nanocarrier drug delivery techniques have been studied for their potential therapeutic implications in the treatment of HCC. Nanoparticle-based imaging could be effective for more accurate HCC diagnosis. Since its inception, nanomedicine has significantly transformed the approach to both the treatment and diagnostics of liver cancer. Nanoparticles (NPs) are being studied as a potential treatment for liver cancer because of their ability to carry small substances, such as treatment with chemotherapy, microRNA, and therapeutic genes. The primary focus of this study is on the most current discoveries and practical uses of nanomedicine-based diagnostic and therapeutic techniques for liver cancer. In this section, we had gone over what we know about metabolic dysfunction in HCC and the treatment options that attempt to fix it by targeting metabolic pathways. Furthermore, we propose a multi-target metabolic strategy as a viable HCC treatment option. Based on the findings given here, the scientists believe that smart nanomaterials have great promise for improving cancer theranostics and opening up new avenues for tumor diagnosis and treatment.

PRECLINICAL MODELS OF LIVER CÂNCER

•In this review, we described different murine models of carcinogenesis: classic models, new transgenic and combined models, that reproduce the key points for HCC and CCA genesis allowing a better understanding of its genetic physiopathological, and environmental abnormalities. •Each model has its advantages, disadvantages, similarities, and differences with the corresponding human disease and should be chosen according to the specificity of the study. Ultimately, those models can also be used for testing new anticancer therapeutic approaches. •Cholangiocarcinoma has been highlighted, with an increase in prevalence. This review has an important role in understanding the pathophysiology and the development of new drugs. Background - This manuscript provides an overview of liver carcinogenesis in murine models of hepatocellular carcinoma (HCC) and cholangiocarcinoma (CCA). Objective - A review through MEDLINE and EMBASE was performed to assess articles until August 2022.Methods - Search was conducted of the entire electronic databases and the keywords used was HCC, CCA, carcinogenesis, animal models and liver. Articles exclusion was based on the lack of close relation to the subject. Carcinogenesis models of HCC include HCC induced by senescence in transgenic animals, HCC diet-induced, HCC induced by chemotoxicagents, xenograft, oncogenes, and HCC in transgenic animals inoculated with B and C virus. The models of CCA include the use of dimethylnitrosamine (DMN), diethylnitrosamine (DEN), thioacetamide (TAA), and carbon tetrachloride (CCl4). CCA murine models may also be induced by: CCA cells, genetic manipulation, Smad4, PTEN and p53 knockout, xenograft, and DEN-left median bile duct ligation. Results - In this review, we described different murine models of carcinogenesis that reproduce the key points for HCC and CCA genesis allowing a better understanding of its genetic, physiopathological, and environmental abnormalities. Conclusion - Each model has its advantages, disadvantages, similarities, and differences with the corresponding human disease and should be chosen according to the specificity of the study. Ultimately, those models can also be used for testing new anticancer therapeutic approaches.

Molecular mechanisms in thioacetamide-induced acute and chronic liver injury models

Thioacetamide (TAA) undergoes bioactivation in the liver by the CYP450 2E1 enzyme, resulting in the formation of TAA-S-oxide and TAA-S-dioxide. TAA-S-dioxide induces oxidative stress via lipid peroxidation of the hepatocellular membrane. A single TAA dose (50-300 mg/kg) administration initiates hepatocellular necrosis around the pericentral region after its covalent binding to macromolecules in the liver. Intermittent TAA administration (150-300 mg/kg, weekly thrice, for 11-16 weeks) activates transforming growth factor (TGF)-β/smad3 downstream signaling in injured hepatocytes, causing hepatic stellate cells (HSCs) to acquire myofibroblast like phenotype. The activated HSCs synthesize a variety of extracellular matrix, leading to liver fibrosis, cirrhosis, and portal hypertension. The TAA induced liver injury varies depending on the animal model, dosage, frequency, and routes of administration. However, TAA induces hepatotoxicity in a reproducible manner, and it is an ideal model to evaluate the antioxidant, cytoprotective, and antifibrotic compounds in experimental animals.

A hepatoprotective role of peritumoral non-parenchymal cells in early liver tumorigenesis

Various 3D models of hepatocytes (HCs) have been established to assess liver functions in vitro. The contribution of the hepatic non-parenchymal cells (NPCs), however, is largely neglected in these models. Here, we report a comparative study of hepatic spheroids generated from freshly isolated mouse whole liver cells (WLCs) and HCs (referred to as SphWLC and SphHC, respectively). We found that HC differentiation was preserved better in SphWLC than in SphHC, and, when co-cultured with liver tumor spheroids (SphT), SphWLC showed more potent suppression of SphT growth compared to SphHC. Histological characterization revealed marked activation and accumulation of hepatic stellate cells (HSCs) at the SphWLC:SphT interface. We found that mixing HSCs in both 3D and 2D HC:tumor co-cultures provided potent protection to HCs against tumor-induced cell death. Activation of HSCs at the tumor border was similarly found in liver tumors from both mice and patients. Overall, our study suggests a hepatoprotective role of peritumoral HSCs in liver tumorigenesis and the potential application of SphWLC as a useful 3D model for dissecting the liver's response to tumorigenesis in vitro.

PRMT5 determines the pattern of polyploidization and prevents liver from cirrhosis and carcinogenesis

Human hepatocellular carcinoma (HCC) occurs almost exclusively in cirrhotic livers. Here, we report that hepatic loss of protein arginine methyltransferase 5 (PRMT5) in mice is sufficient to cause cirrhosis and HCC in a clinically relevant way. Furthermore, pathological polyploidization induced by hepatic loss of PRMT5 promotes liver cirrhosis and hepatic tumorigenesis in aged liver. The loss of PRMT5 leads to hyper-accumulation of P21 and endoreplication-dependent formation of pathological mono-nuclear polyploid hepatocytes. PRMT5 and symmetric dimethylation at histone H4 arginine 3 (H4R3me2s) directly associate with chromatin of P21 to suppress its transcription. More importantly, loss of P21 rescues the pathological mono-nuclear polyploidy and prevents PRMT5-deficiency-induced liver cirrhosis and HCC. Thus, our results indicate that PRMT5-mediated symmetric dimethylation at histone H4 arginine 3 (H4R3me2s) is crucial for preventing pathological polyploidization, liver cirrhosis and tumorigenesis in mouse liver.

Early Subcellular Hepatocellular Alterations in Mice Post Hydrodynamic Transfection: An Explorative Study

Hydrodynamic transfection (HT) or hydrodynamic tail vein injection (HTVi) is among the leading technique that is used to deliver plasmid genes mainly into the liver of live mice or rats. The DNA constructs are composed of coupled plasmids, while one contains the gene of interest that stably integrate into the hepatocyte genome with help of the other consisting sleeping beauty transposase system. The rapid injection of a large volume of DNA-solution through the tail vein induces an acute cardiac congestion that refluxed into the liver, mainly in acinus zone 3, also found through our EM study. Although, HT mediated hydrodynamic force can permeabilizes the fenestrated sinusoidal endothelium of liver, but the mechanism of plasmid incorporation into the hepatocytes remains unclear. Therefore, in the present study, we have hydrodynamically injected 2 mL volume of empty plasmid (transposon vector) or saline solution (control) into the tail vein of anesthetized C57BL/6J/129Sv mice. Liver tissue was resected at different time points from two animal group conditions, i.e., one time point per animal (1, 5, 10-20, 60 min or 24 and 48 hrs after HT) or multiple time points per animal (0, 1, 2, 5, 10, 20 min) and quickly fixed with buffered 4% osmium tetroxide. The tissues fed with only saline solution was also resected and fixed in the similar way. EM evaluation from the liver ultrathin sections reveals that swiftly after 1 min, the hepatocytes near to the central venule in the acinus zone 3 shows cytoplasmic membrane-bound vesicles. Such vesicles increased in both numbers and size to vacuoles and precisely often found in the proximity to the nucleus. Further, EM affirm these vacuoles are also optically empty and do not contain any electron dense material. Although, some of the other hepatocytes reveals sign of cell damage including swollen mitochondria, dilated endoplasmic reticulum, Golgi apparatus and disrupted plasma membrane, but most of the hepatocytes appeared normal. The ultrastructural findings in the mice injected with empty vector or saline injected control mice were similar. Therefore, we have interpreted the vacuole formation as nonspecific endocytosis without specific interactions at the plasma membrane.

SOCS2 protects against chemical-induced hepatocellular carcinoma progression by modulating inflammation and cell proliferation in the liver

Hepatocellular carcinoma (HCC) is one of the most prevalent and lethal cancers worldwide, but the precise intracellular mechanisms underlying the progression of this inflammation associated cancer are not well established. SOCS2 protein plays an important role in the carcinogenesis of different tumors by regulating cytokine signalling through the JAK/STAT axis. However, its role in HCC is unclear. Here, we investigate the role of SOCS2 in HCC progression and its potential as HCC biomarker. The effects of SOCS2 in HCC progression were evaluated in an experimental model of diethylnitrosamine (DEN)-induced HCC in C57BL/6 and SOCS2 deficient mice, in cultured hepatic cells, and in liver samples from HCC patients. Mice lacking SOCS2 showed higher liver tumor burden with increased malignancy grade, inflammation, fibrosis, and proliferation than their controls. Protein and gene expression analysis reported higher pSTAT5 and pSTAT3 activation, upregulation of different proteins involved in survival and proliferation, and increased levels of proinflammatory and pro-tumoral mediators in the absence of SOCS2. Clinically relevant, downregulated expression of SOCS2 was found in neoplasia from HCC patients compared to healthy liver tissue, correlating with the malignancy grade. In summary, our data show that lack of SOCS2 increases susceptibility to chemical-induced HCC and suggest the tumor suppressor role of this protein by regulating the oncogenic and inflammatory responses mediated by STAT5 and STAT3 in the liver. Hence, SOCS2 emerges as an attractive target molecule and potential biomarker to deepen in the study of HCC treatment.

Simvastatin Induces Apoptosis And Suppresses Hepatocellular Carcinoma Induced In Rats

Hepatocellular carcinoma (HCC) is a frequent primary aggressive cancer, a crucial cause of cancer-related mortality globally. Simvastatin is a well-known safe cholesterol-lowering medication that has been recently shown to suppress cancer progression. Apoptosis is a well-organized and controlled cellular process that happens both physiologically and pathologically leading to executing cell death. Apoptosis is frequently downregulated in cancer cells. In the present study, we aimed to test the effect of simvastatin on HCC progression. HCC was induced in experimental rats by means of diethylnitrose amine (DEN) and thioacetamide (TAA) injections. Gross examination and liver index along with biochemical analysis of hepatic function were evaluated. Serum alpha-feto protein (AFP) concentration was measured by ELISA. Histopathological examination was used for assessing necroinflammatory scores and fibrosis degree. Apoptosis was assessed using immunohistochemistry (IHC) and quantitative PCR (qPCR). Simvastatin was found to induce apoptosis successfully in HCC and improve liver fibrosis, overall hepatic function, and necroinflammatory score. Simvastatin, therefore, may be a potential adjunctive therapeutic option in clinical settings of treating HCC.

Protective Effects of Naringin-Dextrin Nanoformula against Chemically Induced Hepatocellular Carcinoma in Wistar Rats: Roles of Oxidative Stress, Inflammation, Cell Apoptosis, and Proliferation

Nanotechnology holds great promise for the development of treatments for deadly human diseases, such as hepatocellular carcinoma (HCC). In the current study, we compared the hepatoprotective effects of naringin-dextrin nanoparticles (NDNPs) against HCC in male Wistar rats with those of pure naringin and investigated the underlying cellular and molecular mechanisms. HCC was induced by intraperitoneal injection of diethylnitrosamine (DEN, 150 mg/kg body weight (b.w.) per week) for two weeks, followed by oral administration of 2-acetylaminofluorene (2AAF, 20 mg/kg b.w.) four times per week for three weeks. DEN/2AAF-administered rats were divided into three groups that respectively received 1% carboxymethyl cellulose (as vehicle), 10 mg/kg b.w. naringin, or 10 mg/kg b.w. NDNP every other day by oral gavage for 24 weeks. Both naringin and NDNP significantly attenuated the harmful effects of DEN on liver function. Both compounds also suppressed tumorigenesis as indicated by the reduced serum concentrations of liver tumor markers, and this antitumor effect was confirmed by histopathological evaluation. Additionally, naringin and NDNP prevented DEN-induced changes in hepatic oxidative stress and antioxidant activities. In addition, naringin and NDNP suppressed inflammation induced by DEN. Moreover, naringin and NDNP significantly reduced the hepatic expression of Bcl-2 and increased Bax, p53, and PDCD5 expressions. Naringin and NDNP also reduced expression of IQGAP1, IQGAP3, Ras signaling, and Ki-67 while increasing expression of IQGAP2. Notably, NDNP more effectively mitigated oxidative stress and inflammatory signaling than free naringin and demonstrated improved antitumor efficacy, suggesting that this nanoformulation improves bioavailability within nascent tumor sites.

NIK/MAP3K14 in hepatocytes orchestrates NASH to hepatocellular carcinoma progression via JAK2/STAT5 inhibition

OBJECTIVE

Nonalcoholic fatty liver disease (NAFLD) ranges from steatosis to nonalcoholic steatohepatitis (NASH), which often progresses to hepatocellular carcinoma (HCC) through a largely undefined mechanism. NASH and HCC depend on inflammatory signaling, whose master regulator is the NFκB transcription factor family, activated by canonical and non-canonical pathways.

METHODS

Here, we investigated non-canonical NFκB-inducing kinase (NIK/MAP3K14) in metabolic NASH, NASH to HCC transition, and DEN-induced HCC. To this end, we performed dietary and chemical interventions in mice that were analyzed via single nucleus sequencing, gene expression and histochemical methods. Ultimately, we verified our mouse results in human patient samples.

RESULTS

We revealed that hepatocyte-specific NIK deficiency (NIKLKO) ameliorated metabolic NASH complications and reduced hepatocarcinogenesis, independent of its role in the NFκB pathway. Instead, hepatic NIK attenuated hepatoprotective JAK2/STAT5 signaling that is a prerequisite for NASH and NASH to HCC progression in mice and humans.

CONCLUSIONS

Our data suggest NIK-mediated inhibitory JAK2 phosphorylation at serine 633 that might be amenable for future therapeutic interventions in patients.

Towards in vivo photomediated delivery of anticancer peptides: Insights from pharmacokinetic and -dynamic data

An in vivo study of a photoswitchable cytotoxic peptide LMB040 has been undertaken on a chemically induced hepatocellular carcinoma model in immunocompetent rats. We analysed the pharmacokinetic profile of the less toxic photoform ("ring-closed" dithienylethene) of the compound in tumors, plasma, and healthy liver. Accordingly, the peptide can reach a tumor concentration sufficiently high to exert a cytotoxic effect upon photoconversion into the more active ("ring-open") photoform. Tissue morphology, histology, redox state of the liver, and hepatic biochemical parameters in blood serum were analysed upon treatment with (i) the less active photoform, (ii) the in vivo light-activated alternative photoform, and (iii) compared with a reference chemotherapeutic 5-fluorouracil. We found that application of the less toxic form followed by a delayed in vivo photoconversion into the more toxic ring-open form of LMB040 led to a higher overall survival of the animals, and signs of enhanced immune response were observed compared to the untreated animals.

SETD3 Methyltransferase Regulates PLK1 Expression to Promote In Situ Hepatic Carcinogenesis

Background

The development of a new strategy to overcome chemoresistance to hepatocellular carcinoma (HCC) treatment is a long-standing issue. We have previously found that upregulated SETD3 levels are closely correlated with HCC. This study aims to explore the mechanism underlying how upregulation of SETD3 promotes liver carcinogenesis.

Methods

RNA-Sequencing analysis was used to explore the correlation of SETD3 with regulatory targets. In vitro assays including cell proliferation and migration were performed to study the oncogenic roles of SETD3 and PLK1. Western blotting, immunohistochemical staining, and blood biochemical assays were performed to examine protein expression or pathological index in tumor tissues and mice liver tissues. Luciferase reporter system and chromatin immunoprecipitation assays were used to explore the mechanism.

Results

We revealed that SETD3 regulates gene expression in subgroups, including cell division, cell proliferation, and cell cycle, in hepatocellular tumor cells. We found that SETD3 upregulation is associated with elevated PLK1 level in both hepatic tumor cells and clinical liver tissues. We further showed that overexpression of SETD3 promoted tumor cell proliferation and migration, whereas inhibition of PLK1 activity attenuated these phenotypes caused by SETD3. By taking advantage of the Sleep Beauty transposase system, we confirmed that upregulated mouse Setd3 promoted hepatic carcinogenesis in situ, but knockdown of mouse Plk1 mitigated Setd3-promoted tumorigenesis in mice. Mechanistically, we showed that SETD3 could be recruited to the promoter of PLK1 gene to facilitate PLK1 transcription.

Conclusions

Our data demonstrate that elevated SETD3 may promote HCC by enhancing PLK1 expression, which suggests that SETD3 may act as a potential drug target combined with PLK1 inhibition to treat HCC.

Experimental Models of Hepatocellular Carcinoma-A Preclinical Perspective

Hepatocellular carcinoma (HCC), the most frequent form of primary liver carcinoma, is a heterogenous and complex tumor type with increased incidence, poor prognosis, and high mortality. The actual therapeutic arsenal is narrow and poorly effective, rendering this disease a global health concern. Although considerable progress has been made in terms of understanding the pathogenesis, molecular mechanisms, genetics, and therapeutical approaches, several facets of human HCC remain undiscovered. A valuable and prompt approach to acquire further knowledge about the unrevealed aspects of HCC and novel therapeutic candidates is represented by the application of experimental models. Experimental models (in vivo and in vitro 2D and 3D models) are considered reliable tools to gather data for clinical usability. This review offers an overview of the currently available preclinical models frequently applied for the study of hepatocellular carcinoma in terms of initiation, development, and progression, as well as for the discovery of efficient treatments, highlighting the advantages and the limitations of each model. Furthermore, we also focus on the role played by computational studies (in silico models and artificial intelligence-based prediction models) as promising novel tools in liver cancer research.

In vivo anticancer effects of Momordica charantia seed fat on hepatocellular carcinoma in a rat model

Background

Momordica charantia or bitter melon is a well-known vegetable with a number of therapeutic actions in Ayurvedic medicine. Alpha-eleostearic acid, a conjugated trienoic fatty acid present in bitter melon is proven to have anticancer properties. Crude seed oil from local bitter melon varieties could be an effective and economical anticancer therapy.

Objective(s)

The study was conducted to evaluate the anticancer effect of the crude oil from the seeds of Matale green variety of bitter melon on a hepatocellular carcinoma-induced rat model.

Materials and methods

Hepatocellular carcinoma (HCC) was experimentally induced in Wistar rats. Crude seed oil of Matale green bitter melon (MGBM) was supplemented to one treatment group in concurrence with carcinoma induction and to another treatment group after the development of carcinoma. After 168 days, gross morphological, histopathological, biochemical, hematological and gene-expression analysis of treated and control groups were performed.

Results

Oral supplementation of MGBM seed oil showed a statistically significant reduction (p < 0.05) in the average number, diameter and area of hepatic dysplastic nodules and a reduction in the size of histopathological neoplastic lesions in both treatment groups compared to the non-treated control group. The expression of tumor suppressor gene p53 and anti-apoptotic gene Bcl-2 were significantly increased while the expression of apoptotic gene caspase 3 was significantly reduced in the treatment group when MGBM supplementation was in concurrence with carcinogenesis (p < 0.05).

Conclusion

Crude seed oil from the MGBM has anticancer effects against experimentally induced HCC in Wistar rats, specially when supplemented in concurrence with carcinoma induction.

Poly(beta-amino ester) nanoparticles enable tumor-specific TRAIL secretion and a bystander effect to treat liver cancer

Despite initial promise, tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-based approaches to cancer treatment have yet to yield a clinically approved therapy, due to delivery challenges, a lack of potency, and drug resistance. To address these challenges, we have developed poly(beta-amino ester) (PBAE) nanoparticles (NPs), as well as an engineered cDNA sequence encoding a secretable TRAIL (sTRAIL) protein, to enable reprogramming of liver cancer cells to locally secrete TRAIL protein. We show that sTRAIL initiates apoptosis in transfected cells and has a bystander effect to non-transfected cells. To address TRAIL resistance, NP treatment is combined with histone deacetylase inhibitors, resulting in >80% TRAIL-mediated cell death in target cancer cells and significantly slowed xenograft tumor growth. This anti-cancer effect is specific to liver cancer cells, with up to 40-fold higher cell death in HepG2 cancer cells over human hepatocytes. By combining cancer-specific TRAIL NPs with small-molecule-sensitizing drugs, this strategy addresses multiple challenges associated with TRAIL therapy and offers a new potential approach for cancer treatment.

Promotive action of 2-acetylaminofluorene on hepatic precancerous lesions initiated by diethylnitrosamine in rats: Molecular study

BACKGROUND

Diethylnitrosamine (DEN) induces hepatic neoplastic lesions over a prolonged period.

AIM

To investigate the promotive action of 2-acetylaminofluorene (2-AAF) when combined with DEN in order to develop a rat model for induction of precancerous lesion and investigate the molecular mechanism underlying the activity of 2-AAF.

METHODS

The pre-precancerous lesions were initiated by intraperitoneal injection of DEN for three weeks consecutively, followed by one intraperitoneal injection of 2-AAF at three different doses (100, 200 and 300 mg/kg). Rats were separated into naïve, DEN, DEN + 100 mg 2-AAF, DEN + 200 mg 2-AAF, and DEN + 300 mg 2-AAF groups. Rats were sacrificed after 10 wk and 16 wk. Liver functions, level of alpha-fetoprotein, glutathione S-transferase-P and proliferating cell nuclear antigen staining of liver tissues were performed. The mRNA level of RAB11A, BAX, p53, and Cyclin E and epigenetic regulation by long-noncoding RNA (lncRNA) RP11-513I15.6, miR-1262 (microRNA), and miR-1298 were assessed in the sera and liver tissues of the rats.

RESULTS

2-AAF administration significantly increased the percent area of the precancerous foci and cell proliferation along with a significant decrease in RAB11A, BAX, and p53 mRNA, and the increase in Cyclin E mRNA was associated with a marked decrease in lncRNA RP11-513I15.6 expression with a significant increase in both miR-1262 and miR-1298.

CONCLUSION

2-AFF promoted hepatic precancerous lesions initiated through DEN by decreasing autophagy, apoptosis, and tumor suppression genes, along with increased cell proliferation, in a time- and dose-dependent manner. These actions were mediated under the epigenetic regulation of lncRNA RP11-513I15.6/miR-1262/miR-1298.

Optimized protocol for an inducible rat model of liver tumor with chronic hepatocellular injury, inflammation, fibrosis, and cirrhosis

Animal models of liver cancer are instrumental in the study of hepatocarcinogenesis and development of novel therapeutic approaches. Here, we describe steps to establish liver cancer in a rat model, via chronic administration of diethylnitrosamine. This causes liver tumors with a sequential progression of hepatitis, cirrhosis, and tumor formation, which closely mimics the development of human liver cancer. This protocol was optimized to significantly increase the incidence of liver tumor formation and reduce the duration of the procedure.

For complete details on the use and execution of this protocol, please refer to Chen et al. (2020).

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Detailed protocol for a carcinogen-induced rat hepatocellular carcinoma model

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Undergoes a sequential progression of hepatitis, cirrhosis, and tumor formation

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Optimized to significantly increase the incidence of liver tumor formation

Distinct anti-tumoral functions of adaptive immune cells in liver cancer

Hepatocellular carcinoma (HCC) commonly arises in chronically inflamed livers, but may also provoke (anti-tumoral) immune responses. Using non-inflammatory diethylnitrosamine (DEN)-induced liver cancer in mice, we demonstrate that distinct axes of the adaptive immune system, which are also prognostic in human HCC, actively suppress hepatocarcinogenesis by controlling tumor formation and progression.

Phytochemical screening and anticancer activity of the aerial parts extract of Xanthium strumarium L. on HepG2 cancer cell line

Background

Cancer is one of the most considerable concerns because of increasing the death rate all over the world. Recent studies have disclosed that plant extracts exhibit anticancer activity through various mechanisms. Xanthium strumarium has been used by Vietnamese in herbal medicines to support the medication of infirmities. This study is to consider the secondary metabolites, antioxidant and anticancer capacities of extract from the aerial parts (stems and leaves) of X. strumarium (AP-XS).

Methods

AP-XS was analyzed for the presence of phytochemicals via qualitative chemical tests and determined total polyphenol and flavonoid contents. DPPH (1,1-diphenyl-2-picrylhydrazyl) quenching assay and sulforhodamine B (SRB) assay were selected to investigate antioxidant capacity and anti-proliferative activity, respectively. Besides, acridine orange-ethidium bromide (AO-EB) dual staining was applied to evaluate the ability to induce apoptosis on HepG2 cancer cells.

Results

Results of present study indicated that AP-XS contains the main phytochemicals such as flavonoids, tannins, saponins, alkaloids, and triterpenes. Ethanol extract had highest content of polyphenol (84.86 mg gallic acid equivalent/g dry mass), and exhibited the great total antioxidant property (IC50 = 184.13 μg/mL) and anti-proliferative activity on HepG2 cancer cells (IC50 = 81.69 μg/mL). Furthermore, the characteristics of apoptosis including shrinkage of the cell and apoptotic bodies were found following 60 h of AP-XS extract treatment through AO-EB dual staining.

Conclusion

The data suggest that AP-XS extract had antioxidant potential and anti-proliferative effect. The anti-proliferative property was considered to have an association with a rising of apoptosis. These results were reliable for further research on X. strumarium as a source of phytochemicals with anticancer activity potential for cancer therapeutics.

Hepatocellular carcinoma

Liver cancer remains a global health challenge, with an estimated incidence of >1 million cases by 2025. Hepatocellular carcinoma (HCC) is the most common form of liver cancer and accounts for ~90% of cases. Infection by hepatitis B virus and hepatitis C virus are the main risk factors for HCC development, although non-alcoholic steatohepatitis associated with metabolic syndrome or diabetes mellitus is becoming a more frequent risk factor in the West. Moreover, non-alcoholic steatohepatitis-associated HCC has a unique molecular pathogenesis. Approximately 25% of all HCCs present with potentially actionable mutations, which are yet to be translated into the clinical practice. Diagnosis based upon non-invasive criteria is currently challenged by the need for molecular information that requires tissue or liquid biopsies. The current major advancements have impacted the management of patients with advanced HCC. Six systemic therapies have been approved based on phase III trials (atezolizumab plus bevacizumab, sorafenib, lenvatinib, regorafenib, cabozantinib and ramucirumab) and three additional therapies have obtained accelerated FDA approval owing to evidence of efficacy. New trials are exploring combination therapies, including checkpoint inhibitors and tyrosine kinase inhibitors or anti-VEGF therapies, or even combinations of two immunotherapy regimens. The outcomes of these trials are expected to change the landscape of HCC management at all evolutionary stages.

Animal Models: A Useful Tool to Unveil Metabolic Changes in Hepatocellular Carcinoma

Simple Summary

Hepatocellular carcinoma (HCC) represents an important health problem. At the moment, systemic therapies offered only modest clinical benefits. Thus, HCC represents a cancer extremely difficult to treat, and therapeutic breakthroughs are urgently needed. Metabolic reprogramming of neoplastic cells has been recognized as one of the core hallmarks of cancer. Experimental animal models represent an important tool that allows to investigate metabolic changes underlying HCC development and progression. In the present review, we characterize available rodent models of hepatocarcinogenesis. Moreover, we discuss the possibility that pharmacological targeting of Warburg metabolism may represent an additional tool to improve already available therapeutic approaches for HCC.

Abstract

Hepatocellular carcinoma (HCC) is one the most frequent and lethal human cancers. At present, no effective treatment for advanced HCC exist; therefore, the overall prognosis for HCC patients remains dismal. In recent years, a better knowledge of the signaling pathways involved in the regulation of HCC development and progression, has led to the identification of novel potential targets for therapeutic strategies. However, the obtained benefits from current therapeutic options are disappointing. Altered cancer metabolism has become a topic of renewed interest in the last decades, and it has been included among the core hallmarks of cancer. In the light of growing evidence for metabolic reprogramming in cancer, a wide number of experimental animal models have been exploited to study metabolic changes characterizing HCC development and progression and to further expand our knowledge of this tumor. In the present review, we discuss several rodent models of hepatocarcinogenesis, that contributed to elucidate the metabolic profile of HCC and the implications of these changes in modulating the aggressiveness of neoplastic cells. We also highlight the apparently contrasting results stemming from different animal models. Finally, we analyze whether these observations could be exploited to improve current therapeutic strategies for HCC.

Rational combination therapy for hepatocellular carcinoma with PARP1 and DNA-PK inhibitors

Understanding differences in DNA double-strand break (DSB) repair between tumor and normal tissues would provide a rationale for developing DNA repair-targeted cancer therapy. Here, using knock-in mouse models for measuring the efficiency of two DSB repair pathways, homologous recombination (HR) and nonhomologous end-joining (NHEJ), we demonstrated that both pathways are up-regulated in hepatocellular carcinoma (HCC) compared with adjacent normal tissues due to altered expression of DNA repair factors, including PARP1 and DNA-PKcs. Surprisingly, inhibiting PARP1 with olaparib abrogated HR repair in HCC. Mechanistically, inhibiting PARP1 suppressed the clearance of nucleosomes at DNA damage sites by blocking the recruitment of ALC1 to DSB sites, thereby inhibiting RPA2 and RAD51 recruitment. Importantly, combining olaparib with NU7441, a DNA-PKcs inhibitor that blocks NHEJ in HCC, synergistically suppressed HCC growth in both mice and HCC patient-derived-xenograft models. Our results suggest the combined inhibition of both HR and NHEJ as a potential therapy for HCC.

Tristetraprolin Promotes Hepatic Inflammation and Tumor Initiation but Restrains Cancer Progression to Malignancy

BACKGROUND & AIMS

Tristetraprolin (TTP) is a key post-transcriptional regulator of inflammatory and oncogenic transcripts. Accordingly, TTP was reported to act as a tumor suppressor in specific cancers. Herein, we investigated how TTP contributes to the development of liver inflammation and fibrosis, which are key drivers of hepatocarcinogenesis, as well as to the onset and progression of hepatocellular carcinoma (HCC).

METHODS

TTP expression was investigated in mouse/human models of hepatic metabolic diseases and cancer. The role of TTP in nonalcoholic steatohepatitis and HCC development was further examined through in vivo/vitro approaches using liver-specific TTP knockout mice and a panel of hepatic cancer cells.

RESULTS

Our data demonstrate that TTP loss in vivo strongly restrains development of hepatic steatosis and inflammation/fibrosis in mice fed a methionine/choline-deficient diet, as well as HCC development induced by the carcinogen diethylnitrosamine. In contrast, low TTP expression fostered migration and invasion capacities of in vitro transformed hepatic cancer cells likely by unleashing expression of key oncogenes previously associated with these cancerous features. Consistent with these data, TTP was significantly down-regulated in high-grade human HCC, a feature further correlating with poor clinical prognosis. Finally, we uncover hepatocyte nuclear factor 4 alpha and early growth response 1, two key transcription factors lost with hepatocyte dedifferentiation, as key regulators of TTP expression.

CONCLUSIONS

Although TTP importantly contributes to hepatic inflammation and cancer initiation, its loss with hepatocyte dedifferentiation fosters cancer cells migration and invasion. Loss of TTP may represent a clinically relevant biomarker of high-grade HCC associated with poor prognosis.

Niclosamide-loaded polymeric micelles ameliorate hepatocellular carcinoma in vivo through targeting Wnt and Notch pathways

AIM

Niclosamide (NIC) is an anthelmintic agent repurposed as a potent anticancer agent. However, its use is hindered by its poor solubility. We investigated the underlying mechanisms of NIC anticancer activity employing a novel oral NIC pluronic-based nanoformulation and tested its effect in thioacetamide-induced hepatocellular carcinoma (HCC) in rats. We evaluated its antitumor effect through regulating Wnt/β-catenin and Notch signaling pathways and apoptosis.

MAIN METHODS

Niclosamide-loaded pluronic nanoparticles (NIC-NPs) were optimally developed and characterized with sustained release properties up to 7 days. Sixteen weeks after HCC induction, NIC (70 mg/kg) and an equivalent dose of NIC-NPs were administered orally for 3 consecutive weeks. Hepatocyte integrity was assessed by measuring serum levels of aminotransferases, ALP, GGT, bilirubin, albumin and total protein. HCC development was detected by measuring AFP expression. Necroinflammation and fibrosis were scored by histopathological examination. Wnt/β-catenin and Notch signaling were evaluated by measuring hepatic mRNA levels of Wnt3A, Lrp5 and Lrp6 Co-receptors, Dvl-2, Notch1 and Hes1 and β-catenin protein levels. Apoptosis was assessed by measuring mRNA and protein levels of cyclin D1 and caspase-3.

KEY FINDING

The novel NIC-NPs restored liver integrity, reduced AFP levels and showed improved anticancer and proapoptotic activities compared to drug alone. The inhibitory effect of NIC on Wnt/β-catenin and Notch signaling pathways was potentiated by the NIC-NPs formulation.

SIGNIFICANCE

We conclude that NIC acts by inhibiting Wnt/β-catenin and Notch signaling and inducing apoptosis in HCC. Developing pluronic-based nanoformulations may be a promising approach to improve NIC solubility and offer the possibility of controlled release.

Halo and Pseudohalo Gold(I)-NHC Complexes Derived from 4,5-Diarylimidazoles with Excellent In Vitro and In Vivo Anticancer Activities Against HCC

A series of halo and pseudohalo gold(I)-NHC complexes (NHC-Au-X) (X = Cl, Br, I, NCO, and OAc) derived from 4,5-diarylimidazoles were synthesized, structurally characterized, and analyzed for their biological activities. The most active complex was iodo(1,3-diethyl-4,5-bis(4-methoxyphenyl)imidazol-2-ylidene)gold(I) (6), which was at least 2-fold more cytotoxic than cisplatin and auranofin against hepatocellular carcinoma (HCC) cells. In vivo studies indicated that complex 6 exhibited a considerably higher anticancer efficacy (IRT = 75.7%) than cisplatin (IRT = 44.4%) in a HepG2 xenograft mouse model and ameliorated liver injury caused by CCl₄ in chronic HCC. Further studies revealed that complex 6 can inhibit the expression of the thioredoxin reductase (TrxR) both in vitro and in vivo, block the HepG2 cells in the G2/M phase, induce reactive oxygen species (ROS) production, damage mitochondrial membrane potential (MMP), and promote HepG2 cell apoptosis.

Animal models for liver disease - A practical approach for translational research

Animal models are crucial for improving our understanding of human pathogenesis, enabling researchers to identify therapeutic targets and test novel drugs. In the current review, we provide a comprehensive summary of the most widely used experimental models of chronic liver disease, starting from early stages of fatty liver disease (non-alcoholic and alcoholic) to steatohepatitis, advanced cirrhosis and end-stage primary liver cancer. We focus on aspects such as reproducibility and practicality, discussing the advantages and weaknesses of available models for researchers who are planning to perform animal studies in the near future. Additionally, we summarise current and prospective models based on human tissue bioengineering.

The complexity of the serine glycine one-carbon pathway in cancer

Perturbations in cellular metabolism are ubiquitous in cancer. Here Reina-Campos et al. review the role of one-carbon metabolism in tumorigenesis.

The serine glycine and one-carbon pathway (SGOCP) is a crucially important metabolic network for tumorigenesis, of unanticipated complexity, and with implications in the clinic. Solving how this network is regulated is key to understanding the underlying mechanisms of tumor heterogeneity and therapy resistance. Here, we review its role in cancer by focusing on key enzymes with tumor-promoting functions and important products of the SGOCP that are of physiological relevance for tumorigenesis. We discuss the regulatory mechanisms that coordinate the metabolic flux through the SGOCP and their deregulation, as well as how the actions of this metabolic network affect other cells in the tumor microenvironment, including endothelial and immune cells.

Fermentable fiber-induced hepatocellular carcinoma in mice recapitulates gene signatures found in human liver cancer

Hepatocellular carcinoma (HCC), the most malignant form of primary liver cancer, is the fourth most prevalent cause of cancer mortality globally. It was recently discovered that the dietary fermentable fiber, inulin, can reprogram the murine liver to favor HCC development in a gut microbiota-dependent manner. Determining the molecular pathways that are either over expressed or repressed during inulin-induced HCC would provide a platform of potential therapeutic targets. In the present study, we have combined analysis of the novel inulin-induced HCC murine model and human HCC samples to identify differentially expressed genes (DEGs) in hepatocarcinogenesis. Hepatic transcriptome profiling revealed that there were 674 DEGs in HCC mice compared to mice safeguarded from HCC. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis uncovered enrichment in ECM-receptor interaction, steroid hormone biosynthesis, PPAR signaling pathway, focal adhesion and protein digestion and absorption during inulin-induced HCC. Tandem mass tag based quantitative, multiplexed proteomic analysis delineated 57 differentially expressed proteins, where the over-expressed proteins were associated with cell adhesion molecules, valine, leucine and isoleucine degradation and ECM-receptor interaction. After obtaining the human orthologs of the mouse genes, we did a comparison analysis to level 3 RNA-seq data found in the Cancer Genome Atlas (TCGA) database, corresponding to human HCC (n = 361) and healthy liver (n = 50) samples. Out of the 549 up-regulated and 68 down-regulated human orthologs identified, 142 genes (137 significantly over-expressed and 5 significantly under-expressed) were associated with human HCC. Using univariate survival analysis, we found 27 over-expressed genes involved in cell-cell adhesion and cell division that were associated with poor HCC patient survival. Overall, the genetic and proteomics signatures highlight potential underlying mechanisms in inulin-induced HCC and support that this murine HCC model is human relevant.

Reduction of FoxP3+ Tregs by an immunosuppressive protocol of rapamycin plus Thymalfasin and Huaier extract predicts positive survival benefits in a rat model of hepatocellular carcinoma

Background

Investigate immunoregulation and anti-tumor immunity of FoxP3⁺Tregs after treatment with rapamycin (RAPA/SRL) plus thymalfasin (Zadaxin) and Huaier extract (PS-T) in a hepatocellular carcinoma (HCC) rat model simulating HCC relapse after liver transplant (LT).

Methods

We successfully established a rat model simulating HCC relapse after LT using an optimized chemical induction method with TACROLIMUS, methylprednisolone, and diethylnitrosamine as identified by visible liver nodules and hematoxylin-eosin staining. The model rats were then treated with RAPA, Zadaxin, and PS-T. Immune status changes were analyzed by flow cytometry, and protein expression of Akt and mTOR was determined by western blotting. Cytokines were measured by ELISAs.

Results

Combined therapy by RAPA plus Zadaxin and PS-T obviously alleviated hepatic pathological changes and significantly decreased the levels of FoxP3⁺Tregs in peripheral blood, the spleen, and the liver (P<0.05) and expression of mTOR protein (P<0.01) in the liver, obviously improved survival time (P=0.02). Moreover, the levels of CD8⁺T cells were increased significantly to almost normal levels (P<0.05) in comparison with no SRL monotherapy protocols. Inhibitory cytokines were also decreased in accordance with FoxP3⁺Tregs. Significant decreases of IL-10 and TGF-β were observed after SRL-based therapy (P<0.01) in comparison with the other groups. Serum alpha fetoprotein (AFP) and vascular endothelial growth factor (VEGF) levels were also decreased significantly (P<0.05). FoxP3⁺Tregs showed a negative correlation with CD8⁺ and CD4⁺/CD8⁺T cells and a positive correlation with AFP, and VEGF (P<0.05).

Conclusions

SRL-based therapy reduces FoxP3⁺Tregs to decrease secreted inhibitory cytokines which may enhancement the viability and number of CD8⁺T cells to exert anti-tumor effects that are mainly mediated through the AKT-mTOR signaling pathway.

Synthesis and biological evaluation of gold(III) Schiff base complexes for the treatment of hepatocellular carcinoma through attenuating TrxR activity

Hepatocellular carcinoma (HCC) is one of the most common cancers and a leading cause of death worldwide. Increased thioredoxin reductase (TrxR) levels were recently identified as possible prognostic markers for HCC. Here, four gold(III) complexes 1b-4b bearing Schiff base ligands were synthesized, characterized, and screened for antitumor activity against HCC. All complexes triggered significant antiproliferative effects against HCC cells, especially the most active complex 1b induced HepG2 cells apoptosis by activating the endoplasmic reticulum stress (ERS). 1b could clearly inhibit the TrxR activity to elevate reactive oxygen species (ROS), mediate ERS and lead to mitochondrial dysfunction. Notably, treatment of 1b improved the CCl₄-induced liver damage in vivo by down-regulation of TrxR expression and inflammation level.

A Comparative Investigation of the Ability of Various Aptamer-Functionalized Drug Nanocarriers to Induce Selective Apoptosis in Neoplastic Hepatocytes: In Vitro and In Vivo Outcome

Aptamers offer a significant promise to target various cancers including hepatocellular carcinoma (HCC), for their high affinity and ability to reach the target site(s), non-immunogenicity, and low cost. The targeting ability to neoplastic hepatocytes by the aptamer, TLS 9a with phosphorothioate backbone modification (designated as L5), has not been explored yet. Hence, we investigated the comparative potential of L5 with some other previously reported liver cancer cell-specific aptamers, conjugated on the surface of drug-nanocarriers. Various in vitro studies such as cytotoxicity, in vitro cellular uptake, cell cycle analysis, and investigations related to apoptosis were performed. In vivo studies carried out here include macroscopic and microscopic hepatic alterations in chemically induced hepatocarcinogenesis in rats, upon experimental treatments. The outcome of the investigations revealed that L5-functionalized drug-nanocarrier (PTX-NPL5) had the highest apoptotic potential compared with the other aptamer-conjugated experimental formulations. Further, its maximum internalization by neoplastic hepatocytes and minimum internalization by normal hepatocytes indicate that it had the potential to preferentially target the neoplastic hepatocytes. Data of in vivo studies revealed that PTX-NPL5 reduced tumor incidences and tumor progress. Superior potency of PTX-NPL5 may be due to the maximum affinity of L5 towards neoplastic hepatocytes resulting in maximum permeation of drug-nanocarrier in them. An effective site-specific targeting of neoplastic hepatocytes can be achieved by L5 for preferential delivery of therapeutics. Further, investigations are needed to identify the target protein(s) on neoplastic hepatocytes responsible for ligand-receptor interaction of L5.

Genetically Engineered Mouse Models for Liver Cancer

Liver cancer is the fourth leading cause of cancer-related death globally, accounting for approximately 800,000 deaths annually. Hepatocellular carcinoma (HCC) is the most common type of liver cancer, comprising approximately 80% of cases. Murine models of HCC, such as chemically-induced models, xenograft models, and genetically engineered mouse (GEM) models, are valuable tools to reproduce human HCC biopathology and biochemistry. These models can be used to identify potential biomarkers, evaluate potential novel therapeutic drugs in pre-clinical trials, and develop molecular target therapies. Considering molecular target therapies, a novel approach has been developed to create genetically engineered murine models for HCC, employing hydrodynamics-based transfection (HT). The HT method, coupled with the Sleeping Beauty transposon system or the CRISPR/Cas9 genome editing tool, has been used to rapidly and cost-effectively produce a variety of HCC models containing diverse oncogenes or inactivated tumor suppressor genes. The versatility of these models is expected to broaden our knowledge of the genetic mechanisms underlying human hepatocarcinogenesis, allowing the study of premalignant and malignant liver lesions and the evaluation of new therapeutic strategies. Here, we review recent advances in GEM models of HCC with an emphasis on new technologies.

A novel chemoprotective effect of tiopronin against diethylnitrosamine-induced hepatocellular carcinoma in rats: Role of ASK1/P38 MAPK-P53 signalling cascade

Hepatocellular carcinoma (HCC) is the second leading cause of cancer-related death worldwide. Oxidative stress contributes significantly to HCC pathogenesis. In this study, we investigated the possible chemoprotective effect of the thiol group-containing compound, tiopronin, against HCC induced chemically by diethylnitrosamine (DENA) in rats. In addition, we elucidated the possible underlying molecular mechanism. Adult male Wistar rats were divided into: Control group, DENA-treated group and tiopronin + DENA-treated group. Liver function tests (ALT, AST, ALP, albumin, total and direct bilirubin) as well as alpha fetoprotein (AFP) concentration were measured in the sera of samples. Oxidative stress biomarkers such as malondialdehyde, nitric oxide, catalase and glutathione peroxidase were measured in the liver tissue homogenates. Determination of the phosphorylated apoptosis signal-regulating kinase 1 (phospho-ASK1), phospho-P38 and phospho-P53 proteins by western blotting, caspase 3 by immunofluorescence in addition to histopathological examination of the liver tissues were performed. Our results showed that tiopronin prevented the DENA-induced elevation of the liver function enzymes and AFP. It also preserved the activities of antioxidant enzymes as well as providing protection from the appearance of HCC histopathological features. Interestingly, tiopronin significantly decreased the expression level of phospho-ASK1, phospho-P38 and phospho-P53, caspase 3 in the liver tissues. These novel findings suggested that tiopronin is an antioxidant drug with a chemoprotective effect against DENA-induced HCC through maintaining the normal activity of ASK1/ P38 MAPK/ P53 signalling pathway.

Genomic Perspective on Mouse Liver Cancer Models

Selecting the most appropriate mouse model that best recapitulates human hepatocellular carcinoma (HCC) allows translation of preclinical mouse studies into clinical studies. In the era of cancer genomics, comprehensive and integrative analysis of the human HCC genome has allowed categorization of HCC according to molecular subtypes. Despite the variety of mouse models that are available for preclinical research, there is a lack of evidence for mouse models that closely resemble human HCC. Therefore, it is necessary to identify the accurate mouse models that represent human HCC based on molecular subtype as well as histologic aggressiveness. In this review, we summarize the mouse models integrated with human HCC genomic data to provide information regarding the models that recapitulates the distinct aspect of HCC biology and prognosis based on molecular subtypes.

A new rhodium(I) NHC complex inhibits TrxR: In vitro cytotoxicity and in vivo hepatocellular carcinoma suppression

Thioredoxin reductase (TrxR) is often overexpressed in different types of cancer cells including hepatocellular carcinoma (HCC) cells and regarded as a target with great promise for anticancer drug research and development. Here, we have synthesized and characterized nine new designed rhodium(I) N-heterocyclic carbene (NHC) complexes. All of them were effective towards cancer cells, especially complex 1e was more active than cisplatin and manifested strong antiproliferative activity against HCC cells. In vivo anticancer studies showed that 1e significantly repressed tumor growth in an HCC nude mouse model and ameliorated liver lesions in a chronic HCC model caused by CCl₄. Notably, a mechanistic study revealed that 1e can strongly inhibit TrxR system both in vitro and in vivo. Furthermore, 1e promoted intracellular ROS accumulation, damaged mitochondrial membrane potential, promoted cancer cell apoptosis and blocked the cells in the G1 phase.

Telomere Dysfunction Induces Sirtuin Repression that Drives Telomere-Dependent Disease

Telomere shortening is associated with stem cell decline, fibrotic disorders, and premature aging through mechanisms that are incompletely understood. Here, we show that telomere shortening in livers of telomerase knockout mice leads to a p53-dependent repression of all seven sirtuins. P53 regulates non-mitochondrial sirtuins (Sirt1, 2, 6, and 7) post-transcriptionally through microRNAs (miR-34a, 26a, and 145), while the mitochondrial sirtuins (Sirt3, 4, and 5) are regulated in a peroxisome proliferator-activated receptor gamma co-activator 1 alpha-/beta-dependent manner at the transcriptional level. Administration of the NAD(+) precursor nicotinamide mononucleotide maintains telomere length, dampens the DNA damage response and p53, improves mitochondrial function, and, functionally, rescues liver fibrosis in a partially Sirt1-dependent manner. These studies establish sirtuins as downstream targets of dysfunctional telomeres and suggest that increasing Sirt1 activity alone or in combination with other sirtuins stabilizes telomeres and mitigates telomere-dependent disorders.

Liver Cancer Gene Discovery Using Gene Targeting, Sleeping Beauty, and CRISPR/Cas9

Hepatocellular carcinoma (HCC) is a devastating and prevalent cancer with limited treatment options. Technological advances have enabled genetic screens to be employed in HCC model systems to characterize genes regulating tumor initiation and growth. Relative to traditional methods for studying cancer biology, such as candidate gene approaches or expression analysis, genetic screens have several advantages: they are unbiased, with no a priori selection; can directly annotate gene function; and can uncover gene-gene interactions. In HCC, three main types of screens have been conducted and are reviewed here: (1) transposon-based mutagenesis screens, (2) knockdown screens using RNA interference (RNAi) or the CRISPR/Cas9 system, and (3) overexpression screens using CRISPR activation (CRISPRa) or cDNAs. These methods will be valuable in future genetic screens to delineate the mechanisms underlying drug resistance and to identify new treatments for HCC.

MicroRNA-Based Prophylaxis in a Mouse Model of Cirrhosis and Liver Cancer

Most hepatocellular carcinomas (HCCs) arise in the context of chronic liver disease and/or cirrhosis. Thus, chemoprevention in individuals at risk represents an important but yet unproven approach. In this study, we investigated the ability of microRNA (miRNA)-based molecules to prevent liver cancer development in a cirrhotic model. To this end, we developed a mouse model able to recapitulate the natural progression from fibrosis to HCC, and then we tested the prophylactic activity of an miRNA-based approach in the model. The experiments were carried out in the TG221 transgenic mouse, characterized by the overexpression of miR-221 in the liver and predisposed to the development of liver tumors. TG221 as well as wild-type mice were exposed to the hepatotoxin carbon tetrachloride (CCl4) to induce chronic liver damage. All mice developed liver cirrhosis, but only TG221 mice developed nodular lesions in 100% of cases within 6 months of age. The spectrum of lesions ranged from dysplastic foci to carcinomas. To investigate miRNA-based prophylactic approaches, anti-miR-221 oligonucleotides or miR-199a-3p mimics were administered to TG221 CCl4-treated mice. Compared to control animals, a significant reduction in number, size, and, most significantly, malignant phenotype of liver nodules was observed, thus demonstrating an important prophylactic action of miRNA-based molecules. In summary, in this article, we not only report a simple model of liver cancer in a cirrhotic background but also provide evidence for a potential miRNA-based approach to reduce the risk of HCC development.

The molecular connection of histopathological heterogeneity in hepatocellular carcinoma: A role of Wnt and Hedgehog signaling pathways

Background

Hepatocellular carcinoma (HCC) is leading cause of cancer-related mortality and is categorized among the most common malignancies around the world. It is a heterogeneous tumor, which shows significant degree of histopathological heterogeneity. Despite the apparent histopathological diversity there has been very little distinct correlation between histopathological features and molecular aberrations particularly when it comes to the expression level of Wnt and Hh pathway molecules. The role of Wnt and Hh pathways in relation to HCC behavior viz. histopathological heterogeneity and aggressiveness is not known. Determining the sequential molecular changes and associated histopathological characteristic during HCC initiation, promotion, and progression would probably lead to a better treatment and prognosis.

Methods

N-Nitrosodiethylamine (DEN) induced HCC model in male Wistar rats were established to study the expression level of Wnt and Hh pathway molecules during different stages of hepatocarcinogenesis. Their expression levels were checked at mRNA and protein levels at initiation, promotion, and progression stages of HCC. The expression levels of Wnt and Hh pathway molecules were correlated with biospecimens of HCC patients of different stages.

Results

In the present study we identified the comprehensive change in the expression pattern of Wnt and Hh pathway molecules in DEN induced rodent hepatocarcinogenesis model. Our results demonstrate that β-catenin /CTNNB1 plays important role in tumor initiation and promotion by stimulating tumor cell proliferation. The activated Wnt signaling in early stage of HCC is associated with well-differentiated histological pattern. The Hh activity although activated during the initiation stage but is significantly increased during the early promotion stage of hepatocarcinogenesis. The increased activity of both Wnt & Hh pathways during promotion stage is associated with moderately-differentiated histological pattern and was simultaneously linked with an increased expression of MMP9. Furthermore, our data demonstrated that during the progression stage Wnt pathway is modestly down-regulated but the Hh pathway activity sustained which in turn is associated with aggressive and invasive phenotype and poorly-differentiated histopathology.

Conclusion

Our data uncovers the grade related expression of Wnt and Hh pathway molecules and the potential utility of these molecular signatures in daily clinical practice is to decide best therapy according to patients characteristic. Additionally, our data offer insight into the interaction between Wnt and Hh pathways which triggers HCC development and progression.