Hepatocyte-stellate cell cross-talk in the liver engenders a permissive inflammatory microenvironment that drives progression in hepatocellular carcinoma

Potentiation of hepatic stellate cell activation by extracellular ATP is dependent on P2X7R-mediated NLRP3 inflammasome activation

Purinergic receptor P2x7 (P2x7R) is a key modulator of liver inflammation and fibrosis. The present study aimed to investigate the role of P2x7R in hepatic stellate cells activation. Lipopolysaccharide (LPS) or the conditioned medium (CM) from LPS-stimulated RAW 264.7 mouse macrophages was supplemented to human hepatic stellate cells, LX-2 for 24h and P2x7R selective antagonist A438079 (10μM) was supplemented to LX-2 cells 1h before LPS or CM stimulation. In addition LX-2 cells were primed with LPS for 4h and subsequently stimulated for 30min with 3mM of adenosine 5'-triphosphate (ATP). A438079 was supplemented to LX-2 cells 10min prior to ATP. Directly treated with LPS on LX-2 cells, mRNA expressions of interleukin (IL)-1β, IL-18 and IL-6 were increased, as well as mRNA expressions of P2x7R, caspase-1, apoptosis-associated speck-like protein containing CARD (ASC) and NOD-like receptor family, pyrin domain containing 3 (NLRP3) mRNA. LPS also increased α-smooth muscle actin (α-SMA) and type I collagen mRNA expressions, as well as collagen deposition. Interestingly treatment of LX-2 cells with LPS-activated CM exhibited the greater increase of above factors than those in LX-2 cells directly treated with LPS. Pretreatment of A438079 on LX-2 cells stimulated by LPS or LPS-activated CM both suppressed IL-1β mRNA expression. LPS combined with ATP dramatically increased protein synthesis and cleavage of IL-1β and its mRNA level than those in HSC treated with LPS or ATP alone. Additionally LX-2 cells primed with LPS and subsequently stimulated for 30min with ATP greatly increased mRNA and protein expression of caspase-1, NLRP3 and P2x7R, as well as liver fibrosis markers, α-SMA and type I collagen. These events were remarkably suppressed by A438079 pretreatment. siRNA against P2x7R reduced protein expression of NLRP3 and α-SMA, and suppressed deposition and secretion of type I collagen. The involvement of P2X7R-mediated NLRP3 inflammasome activation in IL-1β production of HSC might contribute to ECM deposition and suggests that blockade of the P2x7R-NLRP3 inflammasome axis represents a potential therapeutic target to liver fibrosis.

The Role of Cancer-Associated Fibroblasts and Fibrosis in Liver Cancer

Liver cancer is the second leading cause of cancer mortality worldwide, causing more than 700,000 deaths annually. Because of the wide landscape of genomic alterations and limited therapeutic success of targeting tumor cells, a recent focus has been on better understanding and possibly targeting the microenvironment in which liver tumors develop. A unique feature of liver cancer is its close association with liver fibrosis. More than 80% of hepatocellular carcinomas (HCCs) develop in fibrotic or cirrhotic livers, suggesting an important role of liver fibrosis in the premalignant environment (PME) of the liver. Cholangiocarcinoma (CCA), in contrast, is characterized by a strong desmoplasia that typically occurs in response to the tumor, suggesting a key role of cancer-associated fibroblasts (CAFs) and fibrosis in its tumor microenvironment (TME). Here, we discuss the functional contributions of myofibroblasts, CAFs, and fibrosis to the development of HCC and CCA in the hepatic PME and TME, focusing on myofibroblast- and extracellular matrix-associated growth factors, fibrosis-associated immunosuppressive pathways, as well as mechanosensitive signaling cascades that are activated by increased tissue stiffness. Better understanding of the role of myofibroblasts in HCC and CCA development and progression may provide the basis to target these cells for tumor prevention or therapy.

Tumor Necrosis Factor-Like Weak Inducer of Apoptosis Promotes Hepatic Stellate Cells Migration via Canonical NF-κB/MMP9 Pathway

In the liver, the signal and function of tumor necrosis factor-like weak inducer of apoptosis (TWEAK) have mainly been assessed in association with liver regeneration. However, the effects of TWEAK on liver fibrosis have not been fully elucidated. To investigate the effects of TWEAK on human hepatic stellate cells (HSCs) and to explore the relevant potential mechanisms, human HSCs line-LX-2 were cultured with TWEAK. Cell migration was detected by transwell assay; cell viability was evaluated by Cell Counting Kit-8; the expression of MMP1, MMP2, MMP3, MMP7, MMP8, MMP9, MMP10, MMP11, MMP12, MMP13 gene was identified by quantitative real-time polymerase chain reaction and western blotting; the activity of matrix metalloproteinases (MMPs) was tested by enzyme-linked immuno sorbent assay; small interfering RNA transfection was applied for depletion of MMP9 and p65. The result of transwell assay revealed that TWEAK promoted LX-2 migration. Subsequently, our data testified that the expression and activity of MMP9 was induced by TWEAK in LX-2 cells, which enhanced the migration. Furthermore, our findings showed that TWEAK upregulated the phosphorylation of IκBα and p65 protein to increase MMP9 expression in LX-2 cells. Meanwhile, the alpha-smooth muscle actin, vimentin and desmin expression were upregulated following TWEAK treatment. The results in the present study revealed that TWEAK promotes HSCs migration via canonical NF-κB/MMP9 pathway, which possibly provides a molecular basis targeting TWEAK for the therapy of liver fibrosis.

Integrative Genomic Analysis Identifies the Core Transcriptional Hallmarks of Human Hepatocellular Carcinoma

Integrative genomics helped characterize molecular heterogeneity in hepatocellular carcinoma (HCC), leading to targeted drug candidates for specific HCC subtypes. However, no consensus was achieved for genes and pathways commonly altered in HCC. Here, we performed a meta-analysis of 15 independent datasets (n = 784 human HCC) and identified a comprehensive signature consisting of 935 genes commonly deregulated in HCC as compared with the surrounding nontumor tissue. In the HCC signature, upregulated genes were linked to early genomic alterations in hepatocarcinogenesis, particularly gains of 1q and 8q. The HCC signature covered well-established cancer hallmarks, such as proliferation, metabolic reprogramming, and microenvironment remodeling, together with specific hallmarks associated with protein turnover and epigenetics. Subsequently, the HCC signature enabled us to assess the efficacy of signature-relevant drug candidates, including histone deacetylase inhibitors that specifically reduced the viability of six human HCC cell lines. Overall, this integrative genomics approach identified cancer hallmarks recurrently altered in human HCC that may be targeted by specific drugs. Combined therapies targeting common and subtype-specific cancer networks may represent a relevant therapeutic strategy in liver cancer. Cancer Res; 76(21); 6374-81. ©2016 AACR.

Regulation of Transdifferentiation and Retrodifferentiation by Inflammatory Cytokines in Hepatocellular Carcinoma

Liver cancers are typically inflammation-associated cancers characterized by close communication between the tumor cells and the tumor environment. This supportive inflammatory environment contributes to the establishment of a pathologic niche consisting of transformed epithelial cells, tumor-educated fibroblasts, endothelial cells, and immunosuppressive immature myeloid cells. Stromal and infiltrated immune cells help determine tumor fate, but the tumor cells themselves, including cancer stem cells, also influence the surrounding cells. This bidirectional communication generates an intricate network of signals that promotes tumor growth. Cell plasticity, which includes transdifferentiation and retrodifferentiation of differentiated cells, increases tumor heterogeneity. Plasticity allows non-cancer stem cells to replenish the cancer stem cell pool, initiate tumorigenesis, and escape the effects of therapeutic agents; it also promotes tumor aggressiveness. There is increasing evidence that an inflammatory environment promotes the retrodifferentiation of tumor cells into stem or progenitor cells; this could account for the low efficacies of some chemotherapies and the high rates of cancer recurrence. Increasing our understanding of the signaling network that connects inflammation with retrodifferentiation could identify new therapeutic targets, and lead to combined therapies that are effective against highly heterogeneous tumors.

Adverse outcome pathway development from protein alkylation to liver fibrosis

In modern toxicology, substantial efforts are undertaken to develop alternative solutions for in vivo toxicity testing. The adverse outcome pathway (AOP) concept could facilitate knowledge-based safety assessment of chemicals that does not rely exclusively on in vivo toxicity testing. The construction of an AOP is based on understanding toxicological processes at different levels of biological organisation. Here, we present the developed AOP for liver fibrosis and demonstrate a linkage between hepatic injury caused by chemical protein alkylation and the formation of liver fibrosis, supported by coherent and consistent scientific data. This long-term process, in which inflammation, tissue destruction, and repair occur simultaneously, results from the complex interplay between various hepatic cell types, receptors, and signalling pathways. Due to the complexity of the process, an adequate liver fibrosis cell model for in vitro evaluation of a chemical's fibrogenic potential is not yet available. Liver fibrosis poses an important human health issue that is also relevant for regulatory purposes. An AOP described with enough mechanistic detail might support chemical risk assessment by indicating early markers for downstream events and thus facilitating the development of an in vitro testing strategy. With this work, we demonstrate how the AOP framework can support the assembly and coherent display of distributed mechanistic information from the literature to support the use of alternative approaches for prediction of toxicity. This AOP was developed according to the guidance document on developing and assessing AOPs and its supplement, the users' handbook, issued by the Organisation for Economic Co-operation and Development.

Proteinase-activated receptor 2 (PAR2) in hepatic stellate cells - evidence for a role in hepatocellular carcinoma growth in vivo

BACKGROUND

Previous studies have established that proteinase-activated receptor 2 (PAR2) promotes migration and invasion of hepatocellular carcinoma (HCC) cells, suggesting a role in HCC progression. Here, we assessed the impact of PAR2 in HCC stromal cells on HCC growth using LX-2 hepatic stellate cells (HSCs) and Hep3B cells as model.

METHODS

PAR2 expression and function in LX-2 cells was analysed by RT-PCR, confocal immunofluorescence, electron microscopy, and [Ca(2+)]i measurements, respectively. The impact of LX-2-expressed PAR2 on tumour growth in vivo was monitored using HCC xenotransplantation experiments in SCID mice, in which HCC-like tumours were induced by coinjection of LX-2 cells and Hep3B cells. To characterise the effects of PAR2 activation in LX-2 cells, various signalling pathways were analysed by immunoblotting and proteome profiler arrays.

RESULTS

Following verification of functional PAR2 expression in LX-2 cells, in vivo studies showed that these cells promoted tumour growth and angiogenesis of HCC xenografts in mice. These effects were significantly reduced when F2RL1 (encoding PAR2) was downregulated by RNA interference (RNAi). In vitro studies confirmed these results demonstrating RNAi mediated inhibition of PAR2 attenuated Smad2/3 activation in response to TGF-β1 stimulation in LX-2 cells and blocked the pro-mitotic effect of LX-2 derived conditioned medium on Hep3B cells. Furthermore, PAR2 stimulation with trypsin or a PAR2-selective activating peptide (PAR2-AP) led to activation of different intracellular signalling pathways, an increased secretion of pro-angiogenic and pro-mitotic factors and proteinases, and an enhanced migration rate across a collagen-coated membrane barrier. Silencing F2RL1 by RNAi or pharmacological inhibition of Src, hepatocyte growth factor receptor (Met), platelet-derived growth factor receptor (PDGFR), p42/p44 mitogen activated protein kinase (MAPK) or matrix-metalloproteinases (MMPs) blocked PAR2-AP-induced migration.

CONCLUSION

PAR2 in HSCs plays a crucial role in promoting HCC growth presumably by mediating migration and secretion of pro-angiogenic and pro-mitotic factors. Therefore, PAR2 in stromal HSCs may have relevance as a therapeutic target of HCC.

Impact of stroma LOXL2 overexpression on the prognosis of intrahepatic cholangiocarcinoma

BACKGROUND

Intrahepatic cholangiocarcinoma (ICC) is associated with a poor prognosis related to early recurrence especially in the remnant liver after surgery. ICC exhibits a dense desmoplastic stroma which plays a pivotal role in ICC aggressiveness. Thus, analyzing gene deregulation in the stroma of ICC may help to identify new prognosis biomarkers and promising therapeutic targets. The aim of this study was to evaluate the clinical relevance of the matrix-remodeling enzyme lysyl oxidase-like 2 (LOXL2) expression in ICC.

MATERIAL AND METHODS

LOXL2 messenger RNA levels were evaluated in microdissected tumoral stroma (TS) and in nontumoral fibrous tissue by gene expression profiling (testing set, n = 10) obtained from gene expression omnibus database and by quantitative real time polymerase chain reaction (validating set, n = 6). LOXL2 protein levels were evaluated by immunohistochemistry on a tissue microarray containing 80 independent patients. The relationship between LOXL2 expression and survival was assessed by univariate and multivariate analyses.

RESULTS

LOXL2 messenger RNA levels were increased in TS, both in the testing and the validating sets (P < 0.01). These results were confirmed at a protein level, with a significantly higher LOXL2 immunostaining in TS (P < 0.01). Univariate analysis revealed that LOXL2 expression was correlated with a poor overall survival and disease-free survival (P < 0.01). Importantly, high expression of LOXL2 was an independent prognostic factor of worst overall survival (hazard ratio = 5.29, confidence interval [CI] 95% = 1.71-16.3, P < 0.01) and disease-free survival (hazard ratio = 5.55, CI 95% = 2.14-14.37, P < 0.01).

CONCLUSIONS

Our study provides additional arguments for a role of extracellular matrix remodeling in ICC aggressiveness and identifies LOXL2 as a new prognostic marker and a promising therapeutic target in ICC.

Effects of Different Anesthetic Methods on Cellular Immune and Neuroendocrine Functions in Patients With Hepatocellular Carcinoma Before and After Surgery

BACKGROUND

Many anesthesia methods have been studies in hepatocellular carcinoma (HCC). We aimed to explore the effects of combined intravenous and inhalation anesthesia and combined general and epidural anesthesia on cellular immune function and neuroendocrine function in patients with HCC before and after surgery.

METHODS

Between September 2012 and April 2014, 72 patients who underwent a hepatectomy in our hospital were enrolled.

RESULTS

Compared with the combined intravenous and inhalation anesthesia group, the combined general and epidural anesthesia group demonstrated increased CD4⁺ /CD8⁺ T cells 0 hr after surgery, increased CD3⁺ , CD4⁺ , CD4⁺ /CD8⁺ cells, and IFN-γ levels 12 hr after surgery, and increased CD3⁺ , CD4⁺ , and CD4⁺ /CD8⁺ cells 24 hr after surgery (all P < 0.05). At 72 hr after surgery, the levels of ACTH and Cor in the combined general and epidural anesthesia group, and the levels of CD3⁺ , CD4⁺ , CD4⁺ /CD8⁺ cells, and IFN-γ in both the combined intravenous and inhalation anesthesia and the combined general and epidural anesthesia groups decreased to pre-surgery levels. Significant differences were observed in the comparisons of CD3⁺ , IL-6, and IL-10 between the combined intravenous and inhalation anesthesia and the combined general and epidural anesthesia groups 72 hr after surgery (all P < 0.05).

CONCLUSION

Our results revealed that combined general and epidural anesthesia plays a crucial role in hepatectomy via the mitigation of the inhibition of immunologic function in HCC patients during the perioperative period. Combined general and epidural anesthesia also hastens the recovery of immunologic suppression after surgery, which can provide a certain reference for the selection of clinical anesthesia in the treatment of HCC.

Integrative functional genomic delineation of the cascades of transcriptional changes involved in hepatocellular carcinoma progression

Development of targeted therapeutics is still at its early stage for hepatocellular carcinoma (HCC) due to the incomplete understanding of the confounding regulations at signaling pathway level. In this investigation, gene co-expression-based networking and integrative functional genomic modeling of HCC mRNA profiles as signaling processes were employed to understand the complex signaling cascades involved in HCC development toward understanding the avenues for targeted therapeutics. Multiple sets of genes and molecular biological processes involved during HCC development were identified from this integrative analysis: (i) Loss of liver cellular features due to the reduced HNF4A & PPAR signaling in the early stages of HCC, (ii) activated inflammatory and stress signals in the cirrhosis stages and (iii) highly activated cellular proliferation with the activated E2F-MYC oncogenic signaling with the gain of embryonic liver stem cell-like features in the advanced stage tumors. Upon connecting these gene-sets with the established drug sensitivity-related gene signatures, targeted therapeutic strategies for the heterogeneous HCC conditions have been identified. PPAR agonist class of drugs for early stage HCC conditions, anti-inflammatory drugs for cirrhosis and topoisomerase inhibitors for the advanced HCC conditions were inferred. Integrative functional genomic analysis of HCC transcriptome profiles at the context of signaling pathways has defined the key molecular processes involved in HCC development. Further, the study highlights the stage-specific and pathway focused targeted therapeutics for HCC. These findings deserve extensive preclinical explorations toward the establishment of targeted therapeutics.

Roles of hepatic stellate cells in liver inflammation: a new perspective

Connected with the intestinal tract through the portal circulation, liver sinusoids function as the first line of defense against extrahepatic stimuli such as bacterial products and other toxic substances. Hepatic stellate cells (HSCs) are pericytes residing in the perisinusoidal space, between sinusoidal endothelial cells and hepatocytes, store vitamin A, and regulate sinusoidal circulation. Following chronic hepatitis, HSCs actively produce extracellular matrices and cause liver fibrosis. In spite of their close position to the liver sinusoids, however, whether HSCs contribute to liver inflammation has remained elusive. Evidence now accumulates to suggest that HSCs actively take part in the regulation of various forms of liver inflammation. Upon inflammatory stimuli from the sinusoids, HSCs produce various inflammatory molecules and interact with other liver cells, thereby recruiting and then activating infiltrating leukocytes and ultimately causing hepatocyte death. On the other hand, HSCs also exert hepatoprotective effects through inhibition of cytokine and chemokine production or induction of immunosuppressive cell population. HSCs therefore integrate cytokine-mediated inflammatory responses in the sinusoids and relay them to the liver parenchyma, either amplifying liver inflammation or suppressing parenchymal damage through immunoregulatory signaling depending on the context.

Gene expression profiling of the tumor microenvironment in human intrahepatic cholangiocarcinoma

Intrahepatic cholangiocarcinoma (ICC) is the second most common type of malignant primary tumors in the liver. ICC is an aggressive cancer with a poor survival and limited therapeutic options. At the histological level, ICC is characterized by an abundant stroma (i.e. the tumor microenvironment that notably includes components of the extracellular matrix, stromal cells and soluble factors). Tumor microenvironment is known to play a key role in tumor onset and progression but it is poorly characterized at the molecular level. Thus, this study was specifically designed to identify genes that are significantly deregulated in the tumor microenvironment of human ICC. Here we provide a detailed description of the experimental design and methods used to acquire the genomic data deposited into Gene Expression Omnibus (GEO) under the accession number GSE45001. Our genomic dataset provides insights on the molecular pathways altered in the microenvironment of ICC and allows the identification of novel ICC biomarkers, as exemplified previously in Hepatology (PMID: 23775819).

Reversal of liver cancer-associated stellate cell-induced stem-like characteristics in SMMC-7721 cells by 8-bromo-7-methoxychrysin via inhibiting STAT3 activation

Hepatic stellate cells (HSCs) that are activated by human hepatocellular carcinoma (HCC) cells secrete a variety of cytokines, which are the main component of the HCC microenvironment. We aimed to determine whether 8-bromo-7-methoxychrysin (BrMC) could interfere in cross-talk of the human hepatic stellate cell line LX-2 and liver cancer stem-like cells (LCSLCs) to inhibit the characteristics of LCSLCs endowed with the capacity of sustaining human hepatocellular carcinoma (HCC) self-renewal and progression, and to identify its potential mechanism of action. We found that the levels of fibroblast activation protein (FAP) were augmented in LX-2 cells treated with the conditioned medium of LCSLCs (LCSLC-CM) compared to those cultured with routine medium, indicating that the LCSLC-CM can activate LX-2 cells to become liver cancer-associated stellate cells (LCAHSCs). Furthermore, sphere forming capability of SMMC-7721 cells was enhanced and stem cell-related protein expression was significantly increased following treatment with the conditioned medium of LCAHSCs (LCAHSC-CM). Moreover, the level of p-STAT3 was increased in LX-2 cells treated with LCSLC-CM and BrMC reduced expression of p-STAT3. Combination of BrMC and the selective inhibitor of STAT3 cucurbitacin I (JSI-124) synergistically suppressed the LCSLC characteristics in SMMC-7721 cells. Collectively, our data showed that BrMC inhibited the interaction between LX-2 cells and HCC-derived CSCs, and did so potentially through modulation of the STAT3 pathway. Future therapeutic strategies employing anti-CSC therapy should confirm the potential of cucurbitacin I (JSI-124) and BrMC as potent therapeutic agents.

Activated hepatic stellate cells promote angiogenesis via interleukin-8 in hepatocellular carcinoma

BACKGROUND

Chemokines have been recognized as important modulators of angiogenesis, and they play critical roles in the development and metastasis of hepatocellular carcinoma (HCC), although their origins and latent molecular mechanisms remain elusive. The aim of this study was to investigate how activated hepatic stellate cells (a-HSCs) promote angiogenesis in HCC.

METHODS

A total of 22 HCC patients were enrolled randomly. We used immunohistochemistry, western blotting, and enzyme-linked immunosorbent assay (ELISA) to analyse the production of interleukin-8 (IL-8) in a-HSCs derived from HCC tissues. The angiogenic effects of IL-8 in vitro and in vivo were assessed by ELISA, real-time quantitative polymerase chain reaction, capillary tube formation assay, and chick embryo chorioallantoic membrane assay.

RESULTS

The present study showed that IL-8 was enriched predominantly in the tumour stroma of HCC tissues and was mainly derived from a-HSCs, rather than from hepatoma cells, in vivo and in vitro. Angiogenesis was most active at the invading edge, which was close to the a-HSCs. The angiogenic effect was dramatically attenuated by an IL-8 neutralizing antibody both in vitro and in vivo. Moreover, the IL-8 neutralizing antibody down-regulated Ser727-phosphorylated STAT3 levels in hepatoma cells treated with a-HSCs conditioned medium.

CONCLUSIONS

These findings reveal that a-HSCs within the stroma of HCC contribute to tumour angiogenesis via IL-8.

Cytoglobin as a Marker of Hepatic Stellate Cell-derived Myofibroblasts

Myofibroblasts play important roles in inflammation, fibrosis and tumorigenesis in chronically inflamed liver. Liver myofibroblasts originate from hepatic stellate cells, portal fibroblasts or mesothelial cells, and they are localized in and around fibrotic septum and portal tracts. Liver myofibroblasts are the source of extracellular matrix materials, including type I collagen and multiple fibrogenic growth factors, such as transforming growth factor-β and vascular endothelial growth factor. Although a detailed characterization of the function of individual myofibroblasts has not been conducted, owing to the lack of appropriate cell markers, recent lineage-tracing technology has revealed the limited contribution of myofibroblasts that are derived from portal fibroblasts to various types of liver fibrosis, as compared with the contribution of hepatic stellate cells. In addition, cytoglobin, which is the fourth globin in mammals and function as a local gas sensor, provides a new perspective on the involvement of stellate cells in fibrosis and carcinogenesis, possibly through its anti-oxidative properties and is a promising new marker that discriminates between myofibroblasts derived from stellate cells and those from portal fibroblasts.

Functional and genetic deconstruction of the cellular origin in liver cancer

During the past decade, research on primary liver cancers has particularly highlighted the uncommon plasticity of differentiated parenchymal liver cells (that is, hepatocytes and cholangiocytes (also known as biliary epithelial cells)), the role of liver progenitor cells in malignant transformation, the importance of the tumour microenvironment and the molecular complexity of liver tumours. Whereas other reviews have focused on the landscape of genetic alterations that promote development and progression of primary liver cancers and the role of the tumour microenvironment, the crucial importance of the cellular origin of liver cancer has been much less explored. Therefore, in this Review, we emphasize the importance and complexity of the cellular origin in tumour initiation and progression, and attempt to integrate this aspect with recent discoveries in tumour genomics and the contribution of the disrupted hepatic microenvironment to liver carcinogenesis.

Metformin inhibits angiogenesis induced by interaction of hepatocellular carcinoma with hepatic stellate cells

Accumulated evidences indicate metformin is associated with reduced risk of hepatocellular carcinoma (HCC) in diabetic patients, which inspired researchers to explore its therapeutic potentials in HCC. Since Hepatic stellate cells (HSCs) are believed to be the key contributors to tumor microenvironment in HCC and promotes tumor development, here, we explored the effect of metformin on tumor angiogenesis induced by interplay of HCC and HSCs. Our results showed that conditional medium from co-culture of HCC/HSCs induced VEGF secretions and stimulated human umbilical vein endothelial cells (HUVEC) tube formation. However, 25 µM metformin could inhibit this angiogenesis effect. Furthermore, knockdown AMPK of HSCs, not HCC, could abolish inhibition caused by metformin. Our finding suggested that metformin could inhibit HCC angiogenesis through targeting on HSCs through AMPK pathway.

Gas6/Axl pathway is activated in chronic liver disease and its targeting reduces fibrosis via hepatic stellate cell inactivation

BACKGROUND & AIMS

Liver fibrosis, an important health concern associated to chronic liver injury that provides a permissive environment for cancer development, is characterized by accumulation of extracellular matrix components mainly derived from activated hepatic stellate cells (HSCs). Axl, a receptor tyrosine kinase and its ligand Gas6, are involved in cell differentiation, immune response and carcinogenesis.

METHODS

HSCs were obtained from WT and Axl(-/-) mice, treated with recombinant Gas6 protein (rGas6), Axl siRNAs or the Axl inhibitor BGB324, and analyzed by western blot and real-time PCR. Experimental fibrosis was studied in CCl4-treated WT and Axl(-/-) mice, and in combination with Axl inhibitor. Gas6 and Axl serum levels were measured in alcoholic liver disease (ALD) and hepatitis C virus (HCV) patients.

RESULTS

In primary mouse HSCs, Gas6 and Axl levels paralleled HSC activation. rGas6 phosphorylated Axl and AKT prior to HSC phenotypic changes, while Axl siRNA silencing reduced HSC activation. Moreover, BGB324 blocked Axl/AKT phosphorylation and diminished HSC activation. In addition, Axl(-/-) mice displayed decreased HSC activation in vitro and liver fibrogenesis after chronic damage by CCl4 administration. Similarly, BGB324 reduced collagen deposition and CCl4-induced liver fibrosis in mice. Importantly, Gas6 and Axl serum levels increased in ALD and HCV patients, inversely correlating with liver functionality.

CONCLUSIONS

The Gas6/Axl axis is required for full HSC activation. Gas6 and Axl serum levels increase in parallel to chronic liver disease progression. Axl targeting may be a therapeutic strategy for liver fibrosis management.

Hepatic stellate cells promote upregulation of epithelial cell adhesion molecule and epithelial-mesenchymal transition in hepatic cancer cells

Microenvironment plays an important role in epithelial-mesenchymal transition (EMT) and stemness of cells in hepatocellular carcinoma (HCC). Epithelial cell adhesion molecule (EpCAM) is known as a tumor stemness marker of HCC. To investigate the relationship between microenvironment and stemness, we performed an in vitro co-culture assay. Four HCC cell lines (HepG2, Hep3B, HuH-7 and PLC/PRF/5) were co-cultured with the TWNT-1 immortalized hepatic stellate cells (HSCs), which create a microenvironment with HCC. Cell proliferation ability was analyzed by flow cytometry (FCM) and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, while migration ability was assessed by a wound healing assay. Expression of EpCAM was analyzed by immunoblotting and FCM. HCC cell lines were co-cultured with TWNT-1 treated with small interfering RNA (siRNA) for TGF-β and HB-EGF; we then analyzed proliferation, migration ability and protein expression using the methods described above. Proliferation ability was unchanged in HCC cell lines co-cultured with TWNT-1. Migration ability was increased in HCC cell lines (HepG2, Hep3B, HuH-7 and PLC/PRF/5) directly (216.2±67.0, 61.0±22.0, 124.0±66.2 and 51.5±40.3%) and indirectly (102.5±22.0, 84.6±30.9, 86.1±25.7 and 73.9±29.7%) co-cultured with TWNT-1 compared with the HCC uni-culture. Immunoblot analysis revealed increased EpCAM expression in the HCC cell lines co-cultured with TWNT-1. Flow cytometry revealed that the population of E-cadherin-/N-cadherin+ and EpCAM-positive cells increased and accordingly, EMT and stemness in the HCC cell line were activated. These results were similar in the directly and indirectly co-cultured samples, indicating that humoral factors were at play. Conversely, HCC cell lines co-cultured with siRNA‑treated TWNT-1 showed decreased migration ability, a decreased population of EpCAM-positive and E-cadherin-/N-cadherin+ cells. Taken together, humoral factors secreted from TWNT-1 promote upregulation of EpCAM and EMT in hepatic cancer cells.

Hepatic stellate cell and monocyte interaction contributes to poor prognosis in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) patients suffer from a poor survival rate and a high incidence of postoperative recurrence. The hepatic microenvironment plays a significant role in the initiation, progression, and recurrence of HCC; however, the causal mechanisms of these phenomena are unclear. Given the predominant underlying fibrotic and cirrhotic conditions of the liver prone to HCC and its recurrence, alterations of components of the inflammatory milieu have been suggested as factors that promote HCC development. In particular, activated hepatic stellate cells (A-HSCs), which play a key role in liver fibrosis and cirrhosis, have been suggested as contributors to the HCC-prone microenvironment. Here, we have identified and validated an A-HSC-specific gene expression signature among nontumor tissues of 319 HCC patients that is significantly and independently associated with HCC recurrence and survival. Peritumoral, rather than tumor tissue-related, A-HSC-specific gene expression is associated with recurrence and poor survival. Analyses of A-HSC-specific gene signatures and further immunohistochemical validation in an additional 143 HCC patients have revealed that A-HSCs preferentially affect monocyte populations, shifting their gene expression from an inflammatory to an immunosuppressive signature. In addition, the interaction between A-HSCs and monocytes induces protumorigenic and progressive features of HCC cells by enhancing cell migration and tumor sphere formation.

CONCLUSION

A-HSCs play a significant role in promoting HCC progression through interaction with and alteration of monocyte activities within the liver microenvironment; thus, disrupting the interactions and signaling events between the inflammatory milieu and components of the microenvironment may be useful therapeutic strategies for preventing HCC tumor relapse.

Protective effects of hepatic stellate cells against cisplatin-induced apoptosis in human hepatoma G2 cells

The effects of hepatic stellate cells (HSCs) on tumorigenicity of HCC have been previously reported. However, the detailed mechanisms responsible for these effects remain unclear. In this study, we investigated the effects of HSCs on cisplatin-induced apoptosis in human hepatoma HepG2 cell lines. HepG2 cells were treated with cisplatin alone or co-cultured with LX-2 cells 3 days before incubation with cisplatin. Cisplatin causes apoptosis in HepG2 cells and LX-2 cells protect HepG2 cells from death. The protection of LX-2 cells against cisplatin-induced cytotoxicity in HepG2 cells appeared to be related to the inhibition of apoptosis, as determined by cytotoxicity assay and nuclear staining analysis. p53 and Bax mRNA levels were elevated, and cell cycle arrest was produced after cisplatin treatment. LX-2 cells suppressed this elevation of p53 and Bax as well as the cell cycle arrest induced by cisplatin, when compared with those of the treated cells with cisplatin alone. The LX-2 cells pretreatment inhibited the cisplatin-induced apoptosis, which was related with the incomplete blockage in p53 activation. In summary, the results of our present study demonstrate that HSCs protect HepG2 cells against cisplatin-induced apoptosis and its protective effects occur via inhibiting the activation of p53, which is of critical importance for enhanced understanding of fundamental cancer biology.

Hepatic stellate cells: central modulators of hepatic carcinogenesis

Hepatocellular carcinoma (HCC) represents the second most common cause of cancer-related death worldwide, and is increasing in incidence. Currently, our therapeutic repertoire for the treatment of HCC is severely limited, and therefore effective new therapies are urgently required. Recently, there has been increasing interest focusing on the cellular and molecular interactions between cancer cells and their microenvironment. HCC represents a unique opportunity to study the relationship between a diseased stroma and promotion of carcinogenesis, as 90 % of HCCs arise in a cirrhotic liver. Hepatic stellate cells (HSC) are the major source of extracellular proteins during fibrogenesis, and may directly, or via secreted products, contribute to tumour initiation and progression. In this review we explore the complex cellular and molecular interplay between HSC biology and hepatocarcinogenesis. We focus on the molecular mechanisms by which HSC modulate HCC growth, immune cell evasion and angiogenesis. This is followed by a discussion of recent progress in the field in understanding the mechanistic crosstalk between HSC and HCC, and the pathways that are potentially amenable to therapeutic intervention. Furthermore, we summarise the exciting recent developments in strategies to target HSC specifically, and novel techniques to deliver pharmaceutical agents directly to HSC, potentially allowing tailored, cell-specific therapy for HCC.

Hepatic stellate cell and monocyte interaction contributes to poor prognosis in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) patients suffer from a poor survival rate and a high incidence of postoperative recurrence. The hepatic microenvironment plays a significant role in the initiation, progression, and recurrence of HCC; however, the causal mechanisms of these phenomena are unclear. Given the predominant underlying fibrotic and cirrhotic conditions of the liver prone to HCC and its recurrence, alterations of components of the inflammatory milieu have been suggested as factors that promote HCC development. In particular, activated hepatic stellate cells (A-HSCs), which play a key role in liver fibrosis and cirrhosis, have been suggested as contributors to the HCC-prone microenvironment. Here, we have identified and validated an A-HSC-specific gene expression signature among nontumor tissues of 319 HCC patients that is significantly and independently associated with HCC recurrence and survival. Peritumoral, rather than tumor tissue-related, A-HSC-specific gene expression is associated with recurrence and poor survival. Analyses of A-HSC-specific gene signatures and further immunohistochemical validation in an additional 143 HCC patients have revealed that A-HSCs preferentially affect monocyte populations, shifting their gene expression from an inflammatory to an immunosuppressive signature. In addition, the interaction between A-HSCs and monocytes induces protumorigenic and progressive features of HCC cells by enhancing cell migration and tumor sphere formation.

CONCLUSION

A-HSCs play a significant role in promoting HCC progression through interaction with and alteration of monocyte activities within the liver microenvironment; thus, disrupting the interactions and signaling events between the inflammatory milieu and components of the microenvironment may be useful therapeutic strategies for preventing HCC tumor relapse.

Cluster of differentiation 147 is a key molecule during hepatocellular carcinoma cell-hepatic stellate cell cross-talk in the rat liver

The cross-talk between hepatocellular carcinoma (HCC) cells and activated hepatic stellate cells (HSCs) is considered to be important for modulating the biological behavior of tumor cells. However, the molecular links between inflammation and cancer in the activation of HSCs remain to be elucidated. The present study demonstrated that cluster of differentiation (CD)147 is a key molecule involved in the interaction between HCC cells and HSCs. The effects of conditioned medium from human HCC cells on the activation of the human HSC line, LX-2, were assessed using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, western blotting and reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Western blotting, RT-qPCR and gelatin zymography were also used to investigate the effects of CD147 on the activation of LX-2. The expression levels of α-smooth muscle actin (α-SMA) and CD147 were assessed in a co-culture system of LX-2 and FHCC-98 cells by immunofluorescence staining and immunoblotting. In hepatic tissues from a rat model of fibrosis, immunohistochemistry and immunoblotting were performed to detect the expression levels of α-SMA and CD147. Tumor-conditioned medium and CD147 promoted cell proliferation, activated LX-2 cells, increased the expression levels of α-SMA, collagen I and tissue inhibitor of metalloproteinase-1 (TIMP-1), and increased the secretion of matrix metalloproteinase (MMP)-2. The HSCs, which were induced in the co-culture system of HCC cells and HSCs exhibited marked expression levels of CD147. In the hepatic tissue of rat models of fibrosis induced by CCl4, marked expression levels of CD147 were observed in the activated HSCs. Therefore, CD147 promoted the activation of HSCs and was a key molecule during HCC cell-HSC cross-talk in the rat liver.

Role of activated hepatic stellate cells in proliferation and metastasis of hepatocellular carcinoma

AIM

Cancer is not only influenced by specific tumor cells but also by the stromal microenvironment. Upon liver damage, activated hepatic stellate cells (aHSC) become highly proliferative myofibroblast-like cells and are thought to secrete molecules that influence development of hepatocellular carcinoma (HCC). The aim of this study was to investigate the role of aHSC in the development of HCC.

METHODS

To assess if aHSC secreted factor(s) that promote microvascular endothelial cell (MEC) tube formation, MEC were plated with aHSC-conditioned medium and tube formation analyzed by light microscopy. An established transendothelial migration assay with MEC was used to evaluate the role of aHSC in migration and metastasis. A novel in vitro and in vivo orthotopic mouse HCC tumor model was used to investigate angiogenic, proliferative and metastatic activity of aHSC.

RESULTS

We found that aHSC promoted angiogenesis both in vitro and in vivo through vascular endothelial growth factor (VEGF). aHSC-conditioned medium increased the ability of MEC to form tubes which was dependent upon aHSC-secreted VEGF. In addition, HCC orthogenic tumors derived from co-injection of H22 cells plus aHSC into the hepatic lobes of mice had greater cell proliferation and vascularization, as evaluated by the presence of CD34 and VEGF expression, than tumors resulting from H22 injections alone. aHSC also migrated from the primary tumor to sites of metastasis.

CONCLUSION

Our findings support aHSC playing multiple roles in HCC development and metastasis.

Targeting the tumor stroma in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common and deadly cancers worldwide. In ninety percent of the cases it develops as a result of chronic liver damage and it is thus a typical inflammation-related cancer characterized by the close relation between the tumor microenvironment and tumor cells. The stromal environment consists out of several cell types, including hepatic stellate cells, macrophages and endothelial cells. They are not just active bystanders in the pathogenesis of HCC, but play an important and active role in tumor initiation, progression and metastasis. Furthermore, the tumor itself influences these cells to create a background that is beneficial for sustaining tumor growth. One of the key players is the hepatic stellate cell, which is activated during liver damage and differentiates towards a myofibroblast-like cell. Activated stellate cells are responsible for the deposition of extracellular matrix, increase the production of angiogenic factors and stimulate the recruitment of macrophages. The increase of angiogenic factors (which are secreted by macrophages, tumor cells and activated stellate cells) will induce the formation of new blood vessels, thereby supplying the tumor with more oxygen and nutrients, thus supporting tumor growth and offering a passageway in the circulatory system. In addition, the secretion of chemokines by the tumor cells leads to the recruitment of tumor associated macrophages. These tumor associated macrophages are key actors of cancer-related inflammation, being the main type of inflammatory cells infiltrating the tumor environment and exerting a tumor promoting effect by secreting growth factors, stimulating angiogenesis and influencing the activation of stellate cells. This complex interplay between the several cell types involved in liver cancer emphasizes the need for targeting the tumor stroma in HCC patients.

The SDF-1/CXCR4 axis induces epithelial–mesenchymal transition in hepatocellular carcinoma

Hepatic stellate cells play a role in the migration process of hepatocellular carcinoma cells. Here, we address the role of the stromal-derived factor-1/CXC chemokine receptor 4 (SDF-1/CXCR4) axis on hepatocellular carcinoma progression. The expression of the SDF-1 and the CXCR4 was determined through western blotting and real-time PCR analysis using hepatic stellate (LX02) and hepatocellular carcinoma (MHCC97, SMMC7721, Hep3B, and HepG2) cell lines depleted of CXCR4 using shRNA. The migration of hepatocellular carcinoma cells following exogenous treatment with SDF-1 or in co-culture cell systems was measured using the Transwell assay. In parallel, the expression of epithelial–mesenchymal transition (EMT) markers was also determined. We found that SDF-1 is highly expressed in the hepatic stellate cell line LX02 and that the hepatocellular carcinoma cells express high levels of CXCR4. Co-culturing hepatocellular carcinoma cells with LX02 or exogenous treatment with SDF-1 induced an EMT as shown by increased migration. In contrast, ablation of CXCR4 expression in HepG2 cells attenuated the migration of HepG2 cells and suppressed the EMT. Thus, hepatic stellate cells can promote hepatocellular carcinoma cell invasion through the SDF-1/CXCR4 axis.

miR-122--a key factor and therapeutic target in liver disease

Being the largest internal organ of the human body with the unique ability of self-regeneration, the liver is involved in a wide variety of vital functions that require highly orchestrated and controlled biochemical processes. Increasing evidence suggests that microRNAs (miRNAs) are essential for the regulation of liver development, regeneration and metabolic functions. Hence, alterations in intrahepatic miRNA networks have been associated with liver disease including hepatitis, steatosis, cirrhosis and hepatocellular carcinoma (HCC). miR-122 is the most frequent miRNA in the adult liver, and a central player in liver biology and disease. Furthermore, miR-122 has been shown to be an essential host factor for hepatitis C virus (HCV) infection and an antiviral target, complementary to the standard of care using direct-acting antivirals or interferon-based treatment. This review summarizes our current understanding of the key role of miR-122 in liver physiology and disease, highlighting its role in HCC and viral hepatitis. We also discuss the perspectives of miRNA-based therapeutic approaches for viral hepatitis and liver disease.

Hepatic stellate cells activated by acidic tumor microenvironment promote the metastasis of hepatocellular carcinoma via osteopontin

Extracellular pH of solid tumor is generally acidic due to excessive glycolysis and poor perfusion. But whether acidic tumor microenvironment influenced the stromal cells infiltrating in tumor remains unknown. As the predominant progenitor of stromal cells in liver, the number of activated hepatic stellate cells (HSCs) was found positively correlated to the acidification level in the tumor tissues of HCC patients in our study. Whereas, in vitro acidic culture condition and in vivo co-implanting xenograft model were adopted to study the response of HSCs and its influence on HCC progression. HSCs were activated under acidic culture condition depending on the phosphorylation of cellular signal-regulated kinase (ERK). Acidity-activated HSCs promoted HCC metastasis in vitro and in vivo. Osteopontin (OPN) excretion from HSCs was increased under acidic condition and proved to promote the migration of HCC cells. Furthermore, the expression level of OPN was significantly associated with myofibroblasts and the combination of α-SMA with OPN was a powerful predictor for poor prognosis of HCC patients. Activation of HSCs in acidic tumor microenvironment represents a novel mechanism for HCC metastasis and provides a potential therapeutic strategy for HCC.

Angiogenin secretion from hepatoma cells activates hepatic stellate cells to amplify a self-sustained cycle promoting liver cancer

Hepatocellular carcinoma (HCC) frequently develops in a pro-inflammatory and pro-fibrogenic environment with hepatic stellate cells (HSCs) remodeling the extracellular matrix composition. Molecules secreted by liver tumors contributing to HSC activation and peritumoral stromal transformation remain to be fully identified. Here we show that conditioned medium from HCC cell lines, Hep3B and HepG2, induced primary mouse HSCs transdifferentiation, characterized by profibrotic properties and collagen modification, with similar results seen in the human HSC cell line LX2. Moreover, tumor growth was enhanced by coinjection of HepG2/LX2 cells in a xenograft murine model, supporting a HCC-HSC crosstalk in liver tumor progression. Protein microarray secretome analyses revealed angiogenin as the most robust and selective protein released by HCC compared to LX2 secreted molecules. In fact, recombinant angiogenin induced in vitro HSC activation requiring its nuclear translocation and rRNA transcriptional stimulation. Moreover, angiogenin antagonism by blocking antibodies or angiogenin inhibitor neomycin decreased in vitro HSC activation by conditioned media or recombinant angiogenin. Finally, neomycin administration reduced tumor growth of HepG2-LX2 cells coinjected in mice. In conclusion, angiogenin secretion by HCCs favors tumor development by inducing HSC activation and ECM remodeling. These findings indicate that targeting angiogenin signaling may be of potential relevance in HCC management.

Alcohol and HCV: implications for liver cancer

Liver cancers are one of the deadliest known malignancies which are increasingly becoming a major public health problem in both developed and developing countries. Overwhelming evidence suggests a strong role of infection with hepatitis B and C virus (HBV and HCV), alcohol abuse, as well as metabolic diseases such as obesity and diabetes either individually or synergistically to cause or exacerbate the development of liver cancers. Although numerous etiologic mechanisms for liver cancer development have been advanced and well characterized, the lack of definite curative treatments means that gaps in knowledge still exist in identifying key molecular mechanisms and pathways in the pathophysiology of liver cancers. Given the limited success with current therapies and preventive strategies against liver cancer, there is an urgent need to identify new therapeutic options for patients. Targeting HCV and or alcohol-induced signal transduction, or virus-host protein interactions may offer novel therapies for liver cancer. This review summarizes current knowledge on the mechanistic development of liver cancer associated with HCV infection and alcohol abuse as well as highlights potential novel therapeutic strategies.

Membrane-to-Nucleus Signals and Epigenetic Mechanisms for Myofibroblastic Activation and Desmoplastic Stroma: Potential Therapeutic Targets for Liver Metastasis?

Cancer-associated fibroblasts (CAFs), the most abundant cells in the tumor microenvironment (TME), are a key source of the extracellular matrix (ECM) that constitutes the desmoplastic stroma. Through remodeling of the reactive tumor stroma and paracrine actions, CAFs regulate cancer initiation, progression, and metastasis, as well as tumor resistance to therapies. The CAFs found in stroma-rich primary hepatocellular carcinomas (HCC) and liver metastases of primary cancers of other organs predominantly originate from hepatic stellate cells (HSTC), which are pericytes associated with hepatic sinusoids. During tumor invasion, HSTCs transdifferentiate into myofibroblasts in response to paracrine signals emanating from either tumor cells or a heterogeneous cell population within the hepatic tumor microenvironment. Mechanistically, HSTC-to-myofibroblast transdifferentiation, also known as, HSTC activation, requires cell surface receptor activation, intracellular signal transduction, gene transcription, and epigenetic signals, which combined ultimately modulate distinct gene expression profiles that give rise to and maintain a new phenotype. The current review defines a paradigm that explains how HSTCs are activated into CAFs to promote liver metastasis. Furthermore, a focus on the most relevant intracellular signaling networks and epigenetic mechanisms that control HSTC activation is provided. Finally, we discuss the feasibility of targeting CAF/activated HSTCs, in isolation or in conjunction with targeting cancer cells, which constitutes a promising and viable therapeutic approach for the treatment of primary stroma-rich liver cancers and liver metastasis.

Inflammatory cytokines promote the retrodifferentiation of tumor-derived hepatocyte-like cells to progenitor cells

Human hepatocellular carcinoma (HCC) heterogeneity promotes recurrence and resistance to therapies. Recent studies have reported that HCC may be derived not only from adult hepatocytes and hepatoblasts but also hepatic stem/progenitors. In this context, HepaRG cells may represent a suitable cellular model to study stem/progenitor cancer cells and the retrodifferentiation of tumor-derived hepatocyte-like cells. Indeed, they differentiate into hepatocyte- and biliary-like cells. Moreover, tumor-derived HepaRG hepatocyte-like cells (HepaRG-tdHep) differentiate into both hepatocyte- and biliary-like cells through a hepatic progenitor. In this study we report the mechanisms and molecular effectors involved in the retrodifferentiation of HepaRG-tdHep into bipotent progenitors. Gene expression profiling was used to identify genomic changes during the retrodifferentiation of HepaRG-tdHep into progenitors. We demonstrated that gene expression signatures related to a poor-prognosis HCC subclass, proliferative progenitors, or embryonic stem cells were significantly enriched in HepaRG progenitors derived from HepaRG-tdHep. HepaRG-tdHep retrodifferentiation is mediated by crosstalk between transforming growth factor beta 1 (TGFβ1) and inflammatory cytokine pathways (e.g., tumor necrosis factor alpha [TNFα] and interleukin 6 [IL6]). Signatures related to TNFα, IL6, and TGFβ activation pathways are induced within the first hour of retrodifferentiation. Moreover, specific activation or inhibition of these signaling pathways allowed us to determine that TNFα and IL6 contribute to the loss of hepatic-specific marker expression and that TGFβ1 induces an epithelial-to-mesenchymal transition of HepaRG-tdHep. Interestingly, the retrodifferentiation process is blocked by the histone deacetylase inhibitor trichostatin A, opening new therapeutic opportunities.

CONCLUSION

Cancer progenitor cells (or metastasis progenitors) may derive from tumor-derived hepatocyte-like cells in an inflammatory environment that is frequently associated with HCC.

Recurrent genetic alterations in hepatitis C-associated hepatocellular carcinoma detected by genomic microarray: a genetic, clinical and pathological correlation study

Background

In the US, approximately 50% of hepatocellular carcinoma (HCC) is caused by hepatitis-C virus (HCV) infection. The molecular mechanism of a malignant transformation of hepatocyte induced by HCV infection is still largely unclear. There are several clinical and pathological staging systems for HCC, but none of them include biological parameters as predictors for prognosis and there has not been a standardized molecular classification of HCC. To understand the underlying pathogenic genetic alterations in HCV-associated HCC and aid in molecular classification of HCC and patient prognosis, microarray analysis of DNA copy number alterations in HCC were conducted using whole genome microarray with DNA from formalin-fixed paraffin-embedded (FFPE) specimens of both cancer tissues and paired nearby cirrhotic non-neoplastic tissues.

Results

Our results show that the most common chromosomal aberrations (>5 Mb) observed in HCC were chromosomal gains of 1q (80%), 8q (60%), 7q (40%), 5p (33%), 7p (33%), Xq (33%), 5q (27%), and Xp (20%), as well as chromosome losses of 17p (40%), 4q21.21-q26 (33%), 8p (33%), 1p36.11-pter (20%), and 9p (20%). Statistically significant smaller copy number alterations (3.9 kb to 644 kb) were identified using STAC algorithm, including losses of FGFR3, RECQL4, NOTCH1, PTEN, TSC2, and/or ASPSCR1 and gains of ETV1and/or MAF. Correlation analysis between genetic data and pathological data showed that gain of 1q21.1-q23.2 and gain of 8q11.1q13.1 are significantly associated with grade 2–4 and moderately or poorly differentiated HCCs, and gain of chromosome 5q was significantly associated with HCCs with vascular invasion, while gain of chromosome 7q is significantly associated with stage I HCCs.

Conclusions

This study has provided a detailed map of genomic aberrations occurring in HCV-associated HCC and has suggested candidate genes. In addition, gene enrichment analysis on the recurrent abnormal regions indicated NF- kappaB and BMP signaling pathways in HCC development and progression. This study demonstrated that genomic microarray test can be used to distinguish HCC from non- neoplastic cirrhotic nodules and to identify prognostic factors associated with HCC progression using pathologically characterized FFPE samples. Our data support the utility of genomic microarray test for the diagnosis, risk stratification, and pathogenic studies of HCC.

Advances in research of tumor microenvironment in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is not just composed of liver cancer cells; it contains several cell types and extracellular matrix that interact with each other, creating a complex interaction network within a permissive microenvironment. The tumor microenvironment in HCC can not only support liver cancer cell growth but also promote tumor invasion through the stimulation of cancer cell proliferation, migration, and invasion and activation of angiogenesis, which together determine the phenotype of HCC. In this review, we provide an overview of current knowledge on the role of the tumor microenvironment in HCC and its application in prognosis prediction and treatment.

Hepatic stellate cells and liver fibrosis

Hepatic stellate cells are resident perisinusoidal cells distributed throughout the liver, with a remarkable range of functions in normal and injured liver. Derived embryologically from septum transversum mesenchyme, their precursors include submesothelial cells that invade the liver parenchyma from the hepatic capsule. In normal adult liver, their most characteristic feature is the presence of cytoplasmic perinuclear droplets that are laden with retinyl (vitamin A) esters. Normal stellate cells display several patterns of intermediate filaments expression (e.g., desmin, vimentin, and/or glial fibrillary acidic protein) suggesting that there are subpopulations within this parental cell type. In the normal liver, stellate cells participate in retinoid storage, vasoregulation through endothelial cell interactions, extracellular matrix homeostasis, drug detoxification, immunotolerance, and possibly the preservation of hepatocyte mass through secretion of mitogens including hepatocyte growth factor. During liver injury, stellate cells activate into alpha smooth muscle actin-expressing contractile myofibroblasts, which contribute to vascular distortion and increased vascular resistance, thereby promoting portal hypertension. Other features of stellate cell activation include mitogen-mediated proliferation, increased fibrogenesis driven by connective tissue growth factor, and transforming growth factor beta 1, amplified inflammation and immunoregulation, and altered matrix degradation. Evolving areas of interest in stellate cell biology seek to understand mechanisms of their clearance during fibrosis resolution by either apoptosis, senescence, or reversion, and their contribution to hepatic stem cell amplification, regeneration, and hepatocellular cancer.

Epithelial cell adhesion molecule is a prognosis marker for intrahepatic cholangiocarcinoma

BACKGROUND

Recently, we identified a gene signature of intrahepatic cholangiocarcinoma (ICC) stroma and demonstrated its clinical relevance for prognosis. The most upregulated genes included epithelial cell adhesion molecule (EpCAM), a biomarker of cancer stem cells (CSC). We hypothesized that CSC biomarkers could predict recurrence of resected ICC.

METHODS

Both functional analysis of the stroma signature previously obtained and immunohistochemistry of 40 resected ICC were performed. The relationships between the expression of CSC markers and clinicopathologic factors including survival were assessed by univariate and multivariable analyzes.

RESULTS

Gene expression profile of the stroma of ICC highlighted embryonic stem cells signature. Immunohistochemistry on tissue microarray showed at a protein level the increased expression of CSC biomarkers in the stroma of ICC compared with nontumor fibrous liver tissue. The overexpression of EpCAM in the stroma of ICC is an independent risk factor for overall (hazard ratio = 2.6; 95% confidence interval, 1.3-5.1; P = 0.005) and disease-free survival (hazard ratio = 2.2; 95% confidence interval, 1.2-4.2; P = 0.012). In addition, the overexpression of EpCAM in nontumor fibrous liver tissue is closely correlated with a worst disease-free survival (P = 0.035).

CONCLUSIONS

Our findings provide new arguments for a potential role of CSC on ICC progression supporting the idea that targeting CSC biomarkers might represent a promise personalized treatment.

Toward the comprehensive understanding of the gut ecosystem via metabolomics-based integrated omics approach

Recent advances in DNA sequencing and mass spectrometry technologies have allowed us to collect more data on microbiome and metabolome to assess the influence of the gut microbiota on human health at a whole-systems level. Major advances in metagenomics and metabolomics technologies have shown that the gut microbiota contributes to host overall health status to a large extent. As such, the gut microbiota is often likened to a measurable and functional organ consisting of prokaryotic cells, which creates the unique gut ecosystem together with the host eukaryotic cells. In this review, we discuss in detail the relationship between gut microbiota and its metabolites like choline, bile acids, phenols, and short-chain fatty acids in the host health and etiopathogenesis of various pathological states such as multiple sclerosis, autism, obesity, diabetes, and chronic kidney disease. By integrating metagenomic and metabolomic information on a systems biology-wide approach, we would be better able to understand this interplay between gut microbiome and host metabolism. Integration of the microbiome, metatranscriptome, and metabolome information will pave the way toward an improved holistic understanding of the complex mammalian superorganism. Through the modeling of metabolic interactions between lifestyle, diet, and microbiota, integrated omics-based understanding of the gut ecosystem is the new avenue, providing exciting novel therapeutic approaches for optimal host health.

Design and development of a robotized system coupled to µCT imaging for intratumoral drug evaluation in a HCC mouse model

Hepatocellular carcinoma (HCC) is one of the most common cancer related deaths worldwide. One of the main challenges in cancer treatment is drug delivery to target cancer cells specifically. Preclinical evaluation of intratumoral drugs in orthotopic liver cancer mouse models is difficult, as percutaneous injection hardly can be precisely performed manually. In the present study we have characterized a hepatoma model developing a single tumor nodule by implantation of Hep55.1C cells in the liver of syngeneic C57BL/6J mice. Tumor evolution was followed up by µCT imaging, and at the histological and molecular levels. This orthotopic, poorly differentiated mouse HCC model expressing fibrosis, inflammation and cancer markers was used to assess the efficacy of drugs. We took advantage of the high precision of a previously developed robotized system for automated, image-guided intratumoral needle insertion, to administer every week in the tumor of the Hep55.1C mouse model. A significant tumor growth inhibition was observed using our robotized system, whereas manual intraperitoneal administration had no effect, by comparison to untreated control mice.

Clinical relevance and therapeutic potential of angiopoietin-like protein 4 in hepatocellular carcinoma

Background

Development of novel adjuvant therapy to eradicate tumor angiogenesis and metastasis is a pressing need for patients with advanced hepatocellular carcinoma (HCC). We aimed to investigate the clinical relevance and therapeutic potential of angiopoietin-like 4 (ANGPTL4) in HCC.

Methods

ANGPTL4 mRNA levels in tumor and non-tumor liver tissues of HCC patients were analyzed to investigate its clinical relevance. The mechanisms of deregulation of ANGPTL4 in HCC were studied by copy number variation (CNV) and CpG methylation analyses. The orthotopic liver tumor nude mice model was applied using a human metastatic cell line. ANGPTL4-overexpressing adenovirus (Ad-ANGPTL4) was injected via portal vein to investigate its anti-tumorigenic and anti-metastatic potentials.

Results

HCC tissues expressed significantly lower levels of ANGPTL4 mRNA than non-tumor tissues. The copy number of ANGPTL4 gene in tumor tissues was significantly lower than in non-tumor tissues of HCC patients. Higher frequency of methylation of CpG sites of ANGPTL4 promoter was detected in tumor tissues compared to non-tumor tissues. Downregulation of ANGPTL4 mRNA in HCC was significantly associated with advanced tumor stage, presence of venous infiltration, poor differentiation, higher AFP level, appearance of tumor recurrence, and poor postoperative overall and disease-free survivals of HCC patients. Treatment with Ad-ANGPTL4 significantly inhibited the in vivo tumor growth, invasiveness and metastasis by promoting tumoral apoptosis, inhibiting tumoral angiogenesis and motility, and suppressing tumor-favorable microenvironment. Moreover, administration of recombinant ANGPTL4 protein suppressed the motility of HCC cells and altered the secretion profile of cytokines from macrophages.

Conclusion

ANGPTL4 is a diagnostic and prognostic biomarker for HCC patients and a potential therapeutic agent to suppress HCC growth, angiogenesis and metastasis.

Increased expression of CCN2, epithelial membrane antigen, and fibroblast activation protein in hepatocellular carcinoma with fibrous stroma showing aggressive behavior

Tumor behavior is affected by the tumor microenvironment, composed of cancer-associated fibroblasts (CAFs). Meanwhile, hepatocellular carcinomas (HCC) with fibrous stroma reportedly exhibit aggressive behavior suggestive of tumor-stroma interaction. However, evidence of the crosstalk remains unclear. In this study, CCN2, epithelial membrane antigen (EMA), fibroblast activation protein (FAP), and keratin 19 (K19) expression was studied in 314 HCCs (cohort 1), 42 scirrhous HCCs (cohort 2), and 36 chronic hepatitis/cirrhosis specimens by immunohistochemistry. Clinicopathological parameters were analyzed according to the expressions of these markers. In tumor epithelial cells from cohort 1, CCN2 and EMA were expressed in 15.3% and 17.2%, respectively, and their expressions were more frequent in HCCs with fibrous stroma (≥5% of tumor area) than those without (P<0.05 for all); CCN2 expression was well correlated with K19 and EMA expression. In tumor stromal cells, FAP expression was found in 6.7%. In cohort 2, CCN2, EMA, and FAP expression was noted in 40.5%, 40.5%, and 66.7%, respectively, which was more frequent than that in cohort 1 (P<0.05 for all). Additionally, EMA expression was associated with the expression of K19, CCN2, and FAP (P<0.05 for all); EMA expressing tumor epithelial cells showed a topographic closeness to FAP-expressing CAFs. Analysis of disease-free survival revealed CCN2 expression to be a worse prognostic factor in both cohort 1 (P = 0.005) and cohort 2 (P = 0.023), as well as EMA as a worse prognostic factor in cohort 2 (P = 0.048). In conclusion, expression of CCN2, EMA, and FAP may be involved in the activation of CAFs in HCC, giving rise to aggressive behavior. Significant correlation between EMA-expressing tumor cells and FAP-expressing CAFs and their topographic closeness suggests possible cross-talk between tumor epithelial cells and stromal cells in the tumor microenvironment of HCC.

Fatty liver creates a pro-metastatic microenvironment for hepatocellular carcinoma through activation of hepatic stellate cells

Fatty liver (FL) is associated with development of hepatocellular carcinoma (HCC). However, whether FL itself promotes the progression of HCC is unclear. We recently found that hepatic stellate cells (HSCs) were prominently activated in the steatotic liver. Here, we investigated whether steatotic livers promote HCC progression and whether HSCs of steatotic liver are associated with HCC progression. We implanted rat HCC cells into diet-induced steatotic livers in rats via portal vein injection. Thereafter, HSCs and HCC cells were co-implanted subcutaneously into nude rats. Migration and proliferation of HCC cells were measured, and activation of ERK and Akt in these cells was determined by western blotting. Chemokines secreted from HSCs and HCC cells were also evaluated by ELISA. Steatotic livers significantly promoted HCC metastasis compared with non-steatotic livers. Additionally, co-implantation of HCC cells with HSCs from steatotic livers produced significantly larger tumors in recipient rats as compared to those induced by HCC cells co-implanted with HSCs from normal livers (NLs). HSCs isolated from steatotic livers, compared with HSCs isolated from NLs, secreted greater amounts of interleukin-1α, vascular endothelial growth factor, and transforming growth factor-β. These cytokines may enhance the proliferation and migration of HCC cells by increasing the phosphorylation of ERK and Akt in HCC cells. Moreover, we noted that the Rho-kinase inhibitor deactivated activated HSCs and attenuated HCC progression. In conclusion, the rat steatotic liver microenvironment favors HCC metastasis, and this effect appears to be promoted by activated HSCs in the steatotic liver.

Translational approaches: From fatty liver to non-alcoholic steatohepatitis

Over the past few decades, non-alcoholic fatty liver disease (NAFLD) has become one, if not the most common, cause of chronic liver disease affecting both adults and children. The increasing number of cases at an early age is the most worrying aspect of this pathology, since it provides more time for its evolution. The spectrum of this disease ranges from liver steatosis to steatohepatitis, fibrosis and in some cases, hepatocellular carcinoma. NAFLD may not always be considered a benign disease and hepatologists must be cautious in the presence of fatty liver. This should prompt the use of the available experimental models to understand better the pathogenesis and to develop a rational treatment of a disease that is dangerously increasing. In spite of the growing efforts, the pathogenesis of NAFLD is still poorly understood. In the present article we review the most relevant hypotheses and evidence that account for the progression of NAFLD to non-alcoholic steatohepatitis (NASH) and fibrosis. The available in vitro and in vivo experimental models of NASH are discussed and revised in terms of their validity in translational studies. These studies must be aimed at the discovery of the still unknown triggers or mediators that induce the progression of hepatic inflammation, apoptosis and fibrosis.

GIV/Girdin is a central hub for profibrogenic signalling networks during liver fibrosis

Progressive liver fibrosis is characterized by the deposition of collagen by activated hepatic stellate cells (HSCs). Activation of HSCs is a multiple receptor-driven process in which profibrotic signals are enhanced, and anti-fibrotic pathways are suppressed. Here we report the discovery of a novel signaling platform comprised of G protein subunit, Gαi and GIV, its guanine exchange factor (GEF), which serves as a central hub within the fibrogenic signalling network initiated by diverse classes of receptors. GIV is expressed in the liver after fibrogenic injury and is required for HSC activation. Once expressed, GIV enhances the profibrotic (PI3K-Akt-FoxO1 and TGFβ-SMAD) and inhibits the anti-fibrotic (cAMP-PKA-pCREB) pathways to skew the signalling network in favor of fibrosis, all via activation of Gαi. We also provide evidence that GIV may serve as a biomarker for progression of fibrosis after liver injury and a therapeutic target for arresting and/or reversing HSC activation during liver fibrosis.

Hepatic stellate cells and extracellular matrix in hepatocellular carcinoma: more complicated than ever

Hepatocellular carcinoma (HCC) is the fifth most common cancer worldwide and the third leading cause of cancer death. Recent epidemiological data indicate that the mortality rate of HCC will double over the next decades in the USA and Europe. Liver cancer progresses in a large percentage of cases during the clinical course of chronic fibro-inflammatory liver diseases leading to cirrhosis. Therefore, HCC development is regarded as the result of different environmental risk factors each involving different genetic, epigenetic- and chromosomal alterations and gene mutations. During tumour progression, the malignant hepatocytes and the activated hepatic stellate cells are accompanied by cancer-associated fibroblasts, myofibroblasts and immune cells generally called tumour stromal cells. This new and dynamic milieu further enhances the responsiveness of tumour cells towards soluble mediators secreted by tumour stromal cells, thus directly affecting the malignant hepatocytes. This results in altered molecular pathways with cell proliferation as the most important mechanism of liver cancer progression. Given this contextual complexity, it is of utmost importance to characterize the molecular pathogenesis of HCC, and to identify the dominant pathways/drivers and aberrant signalling pathways. This will allow an effective therapy for HCC that should combine strategies affecting both cancer and the tumour stromal cells. This review provides an overview of the recent challenges and issues regarding hepatic stellate cells, extracellular matrix dynamics, liver fibrosis/cirrhosis and therapy, tumour microenvironment and HCC.