Molecular mechanisms underlying hepatocellular carcinoma. Viruses. 2009;1:852-872. [PMID: 21994573 PMCID: PMC3185529 DOI: 10.3390/v1030852]

Network pharmacological evaluation of strigolactones efficacy as potential inhibitors against therapeutic targets of hepatocellular carcinoma

PURPOSE

Hepatocellular carcinoma (HCC) is the uncontrolled growth of hepatocytes which results in nearly 5 million deaths worldwide. Specific strategies have been developed to treat HCC, including surgery, chemotherapy and radiotherapy. But, the effective disease dealing requires synergistic collaboration with other approaches, which often results in moderate to severe side effects during and after the treatment period. Therefore, the focus is now shifting to explore and retrieve those plant-based products that could be utilized to treat HCC with maximum efficacy without causing any side effects. Strigolactones (SL) are compounds of plant origin derived from Striga lutea responsible for controlling the branching pattern of stem and have reported anti-cancerous activity by promoting apoptosis at micromolar concentrations. However, little work has been done concerning determining the pharmacogenomic effect of strigolactones on HCC.

METHODS

Current work focuses on comparing therapeutic efficiencies of SL analogs against core targets of HCC using network pharmacology approach, pharmacokinetics analysis, gene ontogeny, functional enrichment analysis, molecular docking and Molecular Dynamics simulation.

RESULTS

Drug-target prediction and functional enrichment analysis showed that HDAC1 and HDAC2 are the core proteins involved in hepatocellular carcinoma that strigolactone analogs can target. Consequently, results from molecular docking and MD simulation analyses report that among all the SL analogs strigol, epistrigol and nijmegen1 can turn out to be most effective in downregulating the expression of HDAC1, HDAC2 and CYP19A.

CONCLUSION

Strigol, epistrigol and nijmegen1 could be used as potential inhibitors against HCC and can be further validated through in vitro/in vivo studies.

Silencing of RND3/RHOE inhibits the growth of human hepatocellular carcinoma and is associated with reversible senescence

Rnd3/RhoE is an atypical Rho GTPase family member, known to be deregulated in many types of cancer. Previously, we showed that RND3 expression is downregulated in hepatocellular carcinoma (HCC) cell lines and tissues. In cancer cells, Rnd3 is involved in the regulation of cell proliferation and cell invasion. The implication of Rnd3 in HCC invasion was importantly studied whereas its role in cell growth needs further investigation. Thus, in this work, we aimed to better understand the impact of Rnd3 on tumor hepatocyte proliferation. Our results indicate that the silencing of RND3 induces a cell growth arrest both in vitro in 2D and 3D culture conditions and in vivo in tumor xenografts. The growth alteration after RND3 silencing in HCC cells is not due to an increase of cell death but to the induction of senescence. This RND3 knockdown-mediated phenomenon is dependent on the decrease of hTERT expression. Interestingly, after re-expression of RND3, these cells are able to bypass senescence and regain the ability to proliferate, with a re-expression of hTERT. Given that a low expression of Rnd3 is linked to the presence of satellite nodules in HCC, the transient senescence state observed might play a role in cancer progression.

The IGF-1 Signaling Pathway in Viral Infections

Insulin-like growth factor-1 (IGF-1) and the IGF-1 receptor (IGF-1R) belong to the insulin-like growth factor family, and IGF-1 activates intracellular signaling pathways by binding specifically to IGF-1R. The interaction between IGF-1 and IGF-1R transmits a signal through a number of intracellular substrates, including the insulin receptor substrate (IRS) and the Src homology collagen (Shc) proteins, which activate two major intracellular signaling pathways: the phosphatidylinositol 3-kinase (PI3K)/AKT and mitogen-activated protein kinase (MAPK) pathways, specifically the extracellular signal-regulated kinase (ERK) pathways. The PI3K/AKT kinase pathway regulates a variety of cellular processes, including cell proliferation and apoptosis. IGF1/IGF-1R signaling also promotes cell differentiation and proliferation via the Ras/MAPK pathway. Moreover, upon IGF-1R activation of the IRS and Shc adaptor proteins, Shc stimulates Raf through the GTPase Ras to activate the MAPKs ERK1 and ERK2, phosphorylate and several other proteins, and to stimulate cell proliferation. The IGF-1 signaling pathway is required for certain viral effects in oncogenic progression and may be induced as an effect of viral infection. The mechanisms of IGF signaling in animal viral infections need to be clarified, mainly because they are involved in multifactorial signaling pathways. The aim of this review is to summarize the current data obtained from virological studies and to increase our understanding of the complex role of the IGF-1 signaling axis in animal virus infections.

Oncogenic and tumor suppressor pathways in subchronic aflatoxicosis in rats: Association with serum and urinary aflatoxin exposure biomarkers

In this study, the changes in oncogenic and tumor suppressor signaling pathways in liver and their association with serum and urinary biomarkers of aflatoxin exposure were evaluated in Wistar rats fed diets containing aflatoxin B1 (AFB1) for 90 days. Rats were divided into four groups (n = 15 per group) and assigned to dietary treatments containing 0 (control), 50 (AFB50), 100 (AFB100) and 200 μg AFB1 kg-1 diet (AFB200). Multiple preneoplastic foci of hepatocytes marked with glutathione-S-transferase-placental form (GST-P) were identified in AFB100 and AFB200 groups. Hepatocellular damage induced by AFB1 resulted in overexpression of cyclin D1 and β-catenin. The liver expression of retinoblastoma (Rb) and p27Kip1 decreased in AFB100 and AFB200 groups, confirming the favorable conditions for neoplastic progression to hepatocellular carcinoma. All samples from rats fed AFB1-contaminated diets had quantifiable AFB1-lysine in serum or urinary AFM1 and AFB1-N7-guanine, with mean levels of 20.42-50.34 ng mL-1, 5.31-37.68 and 39.15-126.37 ng mg-1 creatinine, respectively. Positive correlations were found between AFB1-lysine, AFM1 or AFB1-N7-guanine and GST-P+, β-catenin+ and cyclin D1+ hepatocytes, while Rb + cells negatively correlated with those AFB1 exposure biomarkers. The pathways evaluated are critical molecular mechanisms of AFB1-induced hepatocarcinogenesis in rats.

Role of ellagic acid for the prevention and treatment of liver diseases

Globally, one of the alarming problems is the prevalence and burden of liver diseases, which accounts for 2 million cases per year. Chronic liver aetiologies such as hepatitis infections, alcoholic or non-alcoholic liver disease, environmental agents, and drug-induced toxicity are invariably responsible for liver fibrosis progression to finally hepatocellular carcinoma. Current treatment options are unable to overwhelm and cure liver diseases. Emerging findings suggest researchers' interest in using evidence-based complementary medicine such as ellagic acid with extensive pharmacological properties. They include antioxidant, anti-inflammatory, anti-hyperlipidaemic, anti-viral, anti-angiogenic, and anticancer activity. The molecular functions elicited by ellagic acid include scavenging of free radicals, regulation of lipid metabolism, the prohibition of fibrogenesis response-mediating proteins, inhibits hepatic stellate cells and myofibroblasts, restrains hepatic viral replication, facilitates suppression of growth factors, regulates transcription factors, proinflammatory cytokines, augments the liver immune response, fosters apoptosis and inhibits cell proliferation in tumorigenic cells. This review will most notably focus on preclinical and clinical information based on currently available evidence to warrant ellagic acid's prospective role in preventing liver diseases.

miR-221-3p promotes hepatocellular carcinogenesis by downregulating O6-methylguanine-DNA methyltransferase

This study aimed to investigate the influence of miR-221-3p and O⁶-methylguanine-DNA methyltransferase (MGMT) interaction in human hepatocellular carcinoma (HCC), thereby revealing a novel molecular mechanism of hepatic carcinogenesis involving miR-221-3p and MGMT.

Fluorescence qPCR and immunoblot assays were performed to determine the expression of RNA and protein in HCC tissues and cell lines. We also employed the firefly and Renilla luciferase assay to verify the target relationship between miR-221-3p and MGMT mRNA. Assessments including the MTT assay, wound-healing assay, transwell assay, colony foci formation experiment, and flow cytometric experiment were carried out to determine the viability, migration, invasion, proliferation, cell cycle progression, and apoptosis of SMMC-7721 and BEL-7404 cell lines with the modulated expression of miR-221-3p and MGMT. Compared to healthy tissues and cell line HL7702, miR-221-3p was significantly upregulated but MGMT was significantly downregulated in carcinomas and cancerous cell lines. Forced miR-221-3p overexpression was found to enhance the proliferation, migration, invasion, and clonogenicity of cell lines, but it suppressed cell apoptosis. Findings also revealed that forced miR-221-3p overexpression had little effect on cell cycle progression. After MGMT was confirmed to be atarget gene of miR-221-3p, it was found that the forced upregulation of miR-221-3p downregulated MGMT mRNA and protein levels significantly. MiR-221-3p was identified as an HCC promoting factor, and it specifically inhibited the expression of the MGMT. Besides, the upregulation of miR-221-3p had apositive influence on HCC pathogenesis by inhibiting MGMT expression.

Antiproliferative and Pro-Apoptotic Effect of Uvaol in Human Hepatocarcinoma HepG2 Cells by Affecting G0/G1 Cell Cycle Arrest, ROS Production and AKT/PI3K Signaling Pathway

Natural products have a significant role in the development of new drugs, being relevant the pentacyclic triterpenes extracted from Olea europaea L. Anticancer effect of uvaol, a natural triterpene, has been scarcely studied. The aim of this study was to understand the anticancer mechanism of uvaol in the HepG2 cell line. Cytotoxicity results showed a selectivity effect of uvaol with higher influence in HepG2 than WRL68 cells used as control. Our results show that uvaol has a clear and selective anticancer activity in HepG2 cells supported by a significant anti-migratory capacity and a significant increase in the expression of HSP-60. Furthermore, the administration of this triterpene induces cell arrest in the G₀/G₁ phase, as well as an increase in the rate of cell apoptosis. These results are supported by a decrease in the expression of the anti-apoptotic protein Bcl2, an increase in the expression of the pro-apoptotic protein Bax, together with a down-regulation of the AKT/PI3K signaling pathway. A reduction in reactive oxygen species (ROS) levels in HepG2 cells was also observed. Altogether, results showed anti-proliferative and pro-apoptotic effect of uvaol on hepatocellular carcinoma, constituting an interesting challenge in the development of new treatments against this type of cancer.

TCA Cycle Rewiring as Emerging Metabolic Signature of Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is a common malignancy. Despite progress in treatment, HCC is still one of the most lethal cancers. Therefore, deepening molecular mechanisms underlying HCC pathogenesis and development is required to uncover new therapeutic strategies. Metabolic reprogramming is emerging as a critical player in promoting tumor survival and proliferation to sustain increased metabolic needs of cancer cells. Among the metabolic pathways, the tricarboxylic acid (TCA) cycle is a primary route for bioenergetic, biosynthetic, and redox balance requirements of cells. In recent years, a large amount of evidence has highlighted the relevance of the TCA cycle rewiring in a variety of cancers. Indeed, aberrant gene expression of several key enzymes and changes in levels of critical metabolites have been observed in many solid human tumors. In this review, we summarize the role of the TCA cycle rewiring in HCC by reporting gene expression and activity dysregulation of enzymes relating not only to the TCA cycle but also to glutamine metabolism, malate/aspartate, and citrate/pyruvate shuttles. Regarding the transcriptional regulation, we focus on the link between NF-κB-HIF1 transcriptional factors and TCA cycle reprogramming. Finally, the potential of metabolic targets for new HCC treatments has been explored.

Animal Models of Hepatocellular Carcinoma: The Role of Immune System and Tumor Microenvironment

Hepatocellular carcinoma (HCC) is the most common type of liver cancer in adults and has one of the highest mortality rates of solid cancers. Ninety percent of HCCs are associated with liver fibrosis or cirrhosis developed from chronic liver injuries. The immune system of the liver contributes to the severity of the necrotic-inflammatory tissue damage, the establishment of fibrosis and cirrhosis, and the disease progression towards HCC. Immunotherapies have emerged as an exciting strategy for HCC treatment, but their effect is limited, and an extensive translation research is urgently needed to enhance anti-tumor efficacy and clinical success. Establishing HCC animal models that are analogous to human disease settings, i.e., mimicking the tumor microenvironment of HCC, is extremely challenging. Hence, this review discusses different animal models of HCC by summarizing their advantages and their limits with a specific focus on the role of the immune system and tumor microenvironment.

Hepatocellular Carcinoma: Molecular Mechanisms and Targeted Therapies

Hepatocellular carcinoma (HCC) is one of the most common and lethal malignant tumors worldwide. HCC is a complex process that is associated with several etiological factors, which in turn result in aberrant activation of different cellular and molecular pathways and the disruption of balance between activation and inactivation of protooncogenes and tumor suppressor genes, respectively. Since HCC most often occurs in the setting of a diseased or cirrhotic liver and most of the patients are diagnosed at the late stage of disease, prognosis is generally poor. At present, limited treatment options with marginal clinical benefits are available. Systemic therapy, particularly in the form of conventional cytotoxic drugs, are generally ineffective. In recent years, molecular-targeted therapies have been clinically used to treat various cancers, including liver cancer. This approach inhibits the growth of tumor cells by interfering with molecules that are involved in carcinogenesis, which makes it more selective and specific than cytotoxic chemotherapy. Many clinical trials have been carried out while using molecular targeted drugs in advanced HCC with many more in progress. The clinical trials in HCC to date have evaluated a single-targeted therapy alone, or two or more targeted therapies in parallel. The aim of this review is to provide insight of various molecular mechanisms, leading to HCC development and progression, and also the range of experimental therapeutics for patients with advanced HCC. The review will summarize different clinical trials data the successes and failures of these treatments, as well as the most effective and approved drugs designed against HCC.

Current Research Progress on Long Noncoding RNAs Associated with Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is the second leading cause of mortality among cancers. It has been found that long noncoding RNAs (lncRNAs) are involved in many human cancers, including liver cancer. It has been identified that carcinogenic and tumor-suppressing lncRNAs are associated with complex processes in liver cancer. These lncRNAs may participate in a variety of pathological and biological activities, such as cell proliferation, apoptosis, invasion, and metastasis. Here, we review the regulation and function of lncRNA in liver cancer and evaluate the potential of lncRNA as a new goal for liver cancer.

Mechanisms of hepatocellular carcinoma progression

Hepatocellular carcinoma (HCC) is the most common primary malignancy of the liver. It is the second leading cause of cancer-related deaths worldwide, with a very poor prognosis. In the United States, there has been only minimal improvement in the prognosis for HCC patients over the past 15 years. Details of the molecular mechanisms and other mechanisms of HCC progression remain unclear. Consequently, there is an urgent need for better understanding of these mechanisms. HCC is often diagnosed at advanced stages, and most patients will therefore need systemic therapy, with sorafenib being the most common at the present time. However, sorafenib therapy only minimally enhances patient survival. This review provides a summary of some of the known mechanisms that either cause HCC or contribute to its progression. Included in this review are the roles of viral hepatitis, non-viral hepatitis, chronic alcohol intake, genetic predisposition and congenital abnormalities, toxic exposures, and autoimmune diseases of the liver. Well-established molecular mechanisms of HCC progression such as epithelial-mesenchymal transition, tumor-stromal interactions and the tumor microenvironment, cancer stem cells, and senescence bypass are also discussed. Additionally, we discuss the roles of circulating tumor cells, immunomodulation, and neural regulation as potential new mechanisms of HCC progression. A better understanding of these mechanisms could have implications for the development of novel and more effective therapeutic and prognostic strategies, which are critically needed.

Whole genome sequencing of matched tumor, adjacent non-tumor tissues and corresponding normal blood samples of hepatocellular carcinoma patients revealed dynamic changes of the mutations profiles during hepatocarcinogenesis

Hepatocellular carcinoma (HCC) has become the third most deadly disease worldwide and HBV is the major factor in Asia and Africa. We conducted 9 WGS (whole genome sequencing) analyses for matched samples of tumor, adjacent non-tumor tissues and normal blood samples of HCC patients from three HBV positive patients. We then validated the mutations identified in a larger cohort of 177 HCC patients. We found that the number of the unique somatic mutations (average of 59,136) in tumor samples is significantly less than that in adjacent non-tumor tissues (average 83, 633). We discovered that the TP53 R249S mutation occurred in 7.7% of the HCC patients, and it was significantly associated with poor diagnosis. In addition, we found that the L104P mutation in the VCX gene (Variable charge, X-linked) was absent in white blood cell samples, but present at 11.1% frequency in the adjacent tissues and increased to 14.6% in HCC tissues, suggesting that this mutation might be a tumor driver gene driving HCC carcinogenesis. Finally, we identified a TK1-RNU7 fusion, which would result in a deletion of 103 amino acids from its C-terminal. The frequencies of this fusion event decreased from the adjacent tissues (29.2%) to the tumors (16.7%), suggesting that a truncated thymidine Kinase1 (TK1) caused by the fusion event might be deleterious and be selected against during tumor progression. The three-way comparisons allow the identification of potential driver mutations of carcinogenesis. Furthermore, our dataset provides the research community a valuable dataset for identifying dynamic changes of mutation profiles and driver mutations for HCC.

MiR-758-3p suppresses proliferation, migration and invasion of hepatocellular carcinoma cells via targeting MDM2 and mTOR

Hepatocelluar carcinoma (HCC) is one of the most frequently diagnosed cancers worldwide and among the leading causes of cancer-related death. Although deregulation of microRNAs has been frequently described in HCC, imperfection is known about the precise molecular mechanisms by which microRNAs modulate the process of tumorogenesis and behavior of cancer cells. In this study, we demonstrated that miR-758-3p could suppress cell proliferation, migration and invasion in hepatocellular carcinoma cells. We screened and identified two novel miR-758-3p targets, MDM2 and mTOR. Up-regulation of miR-758-3p could specifically and markedly down-regulate the expression of MDM2 and mTOR. Additionally, miR-758-3p over-expression displayed significant suppression in HCC development. To identify the mechanisms, we further investigated the P53 and mTOR pathway and found that p-p70S6 kinase(Ser371), p-p70 S6 kinase(Thr389) and p-4E-BP1were dramatically down-regulated after miR-758-3p transfection, while an enhanced expression of P53, AKT and PRAS40 were visualized, thus suggesting that the role of miR-758-3p in HCC progression may be associated with MDM2-p53 and mTOR signaling pathways. Collectively, our results indicate that miR-758-3pserves as a tumor suppressor and plays a crucial role in inhibiting the proliferation, migration and invasion of HCC via targeting MDM2 and mTOR and implicate its potential application in cancer therapy.

Prp19 Arrests Cell Cycle via Cdc5L in Hepatocellular Carcinoma Cells

Pre-mRNA processing factor 19 (Prp19) is involved in many cellular events including pre-mRNA processing and DNA damage response. Recently, it has been identified as a candidate oncogene in hepatocellular carcinoma (HCC). However, the role of Prp19 in tumor biology is still elusive. Here, we reported that Prp19 arrested cell cycle in HCC cells via regulating G2/M transition. Mechanistic insights revealed that silencing Prp19 inhibited the expression of cell division cycle 5-like (Cdc5L) via repressing the translation of Cdc5L mRNA and facilitating lysosome-mediated degradation of Cdc5L in HCC cells. Furthermore, we found that silencing Prp19 induced cell cycle arrest could be partially resumed by overexpressing Cdc5L. This work implied that Prp19 participated in mitotic progression and thus could be a promising therapeutic target of HCC.

HBx triggers either cellular senescence or cell proliferation depending on cellular phenotype

Replicative senescence is a hallmark of chronic liver diseases including chronic hepatitis B virus (HBV) infection, whereas HBV-encoded oncoproteins HBx and preS2 have been found to overcome senescence. HBx possesses a C-terminal truncation mainly in hepatocellular carcinomas but also in noncancerous liver tissues. Here, by cell counting, BrdU incorporation, MTT proliferation assay, cell cycle analysis, SA-βgal staining and Western blotting in primary and malignant cells, we investigated the effect of HBx C-terminal mutants on cellular senescence. HBx C-terminal mutants were found to trigger cellular senescence in primary MRC5 cells, and malignant liver cells Huh7, and SK-Hep1. In contrast, these mutants promoted the proliferation of HepG2 malignant liver cells. The pro-senescent effect of HBx relied on an increased p16(INK4a) and p21(Waf1/Cip1) expression, and a decreased phosphorylation of Rb. Together, these results suggest that the two main variants of HBx present in HBV-infected liver possess opposite effects on cellular senescence that depend on the phenotype of infected cells.

WT1 expression is increased in primary fibroblasts derived from Dupuytren's disease tissues

Dupuytren's disease (DD) is a fibroproliferative and contractile fibrosis of the palmar fascia that, like all other heritable fibroses, is currently incurable. While DD is invariably benign, it exhibits some molecular similarities to malignant tumours, including increased levels of ß-catenin, onco-fetal fibronectin, periostin and insulin-like growth factor (IGF)-II. To gain additional insights into the pathogenesis of DD, we have assessed the expression of WT1, encoding Wilm's tumour 1, an established tumour biomarker that is syntenic with IGF2, the gene encoding IGF-II in humans. We found that WT1 expression is robustly and consistently up regulated in primary fibroblasts derived from the fibrotic palmar fascia of patients with DD (DD cells), whereas syngeneic fibroblasts derived from the macroscopically unaffected palmar fascia in these patients and allogeneic fibroblasts derived from normal palmar fascia exhibited very low or undetectable WT1 transcript levels. WT1 immunoreactivity was evident in a subset of cells in the fibrotic palmar fascia of patients with DD, but not in macroscopically unaffected palmar fascia. These findings identify WT1 expression as a novel biomarker of fibrotic palmar fascia and are consistent with the hypothesis that the pathogeneses of DD and malignant tumours have molecular similarities.

AST IV inhibits H₂O₂-induced human umbilical vein endothelial cell apoptosis by suppressing Nox4 expression through the TGF-β1/Smad2 pathway

Endothelial cell apoptosis plays an important role in the pathophysiological mechanisms of vascular complications in diabetes mellitus (DM). NADPH oxidase 4 (Nox4)-dependent reactive oxygen species (ROS) aggregation is the main cause of vascular endothelial cell apoptosis. The transforming growth factor-β1 (TGF-β1)/Smad2 signaling pathway is involved in the apoptosis of several types of cells. However, the association between vascular endothelial cell apoptosis and Nox4, and the involvement of the TGF-β1/Smad2 signaling pathway in vascular endothelial cell apoptosis remain unclear. In the present study, we aimed to investigate the role of Nox4-dependent ROS production and to determine the involvement of the TGF-β1/Smad2 signaling pathway in endothelial cell apoptosis induced by oxidative stress which causes vascular injury in DM. We demonstrated that hydrogen peroxide (H2O2) increased Nox4-dependent-ROS aggregation, as well as the expression of TGF-β1, Smad2, Bax and caspase-3, decreased Bcl-2 expression and increased the apoptosis of human umbilical vein endothelial cells (HUVECs). Treatment with diphenyliodonium (DPI), a specific inhibitor of Nox4 or astragaloside IV (AST IV), a monomer located in an extract of astragaloside, decreased Nox4 expression and the levels of ROS, decreased TGF-β1 and Smad2 expression, altered the expression of apoptosis-related genes and decreased the apoptosis of HUVECs. Treatment with LY2109761, a selective inhibitor of the TGF-β1/Smad2 pathway, produced results similar to those of DPI; however, LY2109761 had no effect on Nox4 expression and ROS levels. Taken together, the findings of the present study suggest that H2O2 contributes to HUVEC apoptosis by inducing Nox4-dependent ROS aggregation and activating the TGF-β1/Smad2 signaling pathway. Our data indicate that the protective effects of AST IV against vascular endothelial cell apoptosis in DM are mainly associated with the decrease in Nox4 expression through the TGF-β1/Smad2 signaling pathway. Furthermore, the inhibition of the activation of the TGF-β1/Smad2 signaling pathway may be another potential therapeutic strategy in the treatment of DM.

Hagen-Poiseuille’s law: The link between cirrhosis, liver stiffness, portal hypertension and hepatic decompensation

The onset of hepatic decompensation in cirrhosis heralds an accelerated downhill course with poor outcome. The sole predictor of this decompensation in cirrhosis is increased hepatic vein to portal vein gradient hepatic venous pressure gradient (HVPG). Surrogate markers of liver function or hepatic reserve appear to be less relevant. The hepatic sinusoids become less elastic and more rigid as liver fibrosis and cirrhosis progress. We propose that the Hagen-Poiseuille’s law, which applies to rigid, but not elastic vessels, determines the pressure-flow characteristics in the sinusoids. In the rigid cirrhotic liver, HVPG rises dramatically with any change in net surface area or radius, r⁴ of the vasculature that follows surgical resection. This review relates liver stiffness to the risk of decompensation in patients with cirrhosis. The liver has a unique dual blood supply comprising a low pressure portal vein and high pressure hepatic artery. We compare the complexity of autoregulation in the normal elastic liver with that in the rigid cirrhotic liver. Therapeutic modalities to reduce portal pressure may reduce the risk of hepatic decompensation and improve outcomes in cirrhosis.

Management of Hepatocellular Carcinoma in Cirrhotic Patients with Portal Hypertension: Relevance of Hagen-Poiseuille's Law

BACKGROUND

Hepatic decompensation in cirrhosis heralds an accelerated course with poor survival. An increase in hepatic venous pressure gradient (HVPG), rather than surrogate tests of liver function, appears to be the sole predictor of decompensation after surgical resection. We propose that hepatic sinusoidal walls become less elastic as cirrhosis progresses. Decompensation signals the development of increased vessel wall rigidity. The pressure-flow characteristics then become subject to Hagen-Poiseuille's law, which applies only to rigid, cylindrical vessels. Thereafter, HVPG rises exponentially (by a factor inversely proportional to the fourth power of the net radius of functional sinusoidal vessels, 1/r(4), at any given hepatic blood flow rate. This review attempts to correlate liver stiffness, risk of decompensation and outcomes from hepatocellular carcinoma (HCC) in patients with cirrhosis.

SUMMARY

We compare the complexity of autoregulation in the normal elastic liver, which has a unique dual blood supply, with that in the rigid cirrhotic liver. We also review, in the context of background liver cirrhosis, the management of HCC which is in essence, a solid mass of unorganized cells that exacerbates liver stiffness. We discuss the differential effects of various therapeutic modalities such as liver transplantation, loco-regional therapy and drugs on HCC outcomes, based on their effects on HVPG.

KEY MESSAGES

Increased hepatic artery supply, or the hepatic artery buffer response, may be the only available method for autoregulation or maintenance of hepatic blood flow in the cirrhotic liver. In HCC, loco-regional therapies, including partial resection of the cirrhotic liver, can exacerbate portal hypertension by increasing blood flow within the remnant organ. We conclude that studies of HVPG reduction as part of HCC management may be beneficial and are warranted.

The GH-IGF-SST system in hepatocellular carcinoma: biological and molecular pathogenetic mechanisms and therapeutic targets

Hepatocellular carcinoma (HCC) is the sixth most common malignancy worldwide. Different signalling pathways have been identified to be implicated in the pathogenesis of HCC; among these, GH, IGF and somatostatin (SST) pathways have emerged as some of the major pathways implicated in the development of HCC. Physiologically, GH-IGF-SST system plays a crucial role in liver growth and development since GH induces IGF1 and IGF2 secretion and the expression of their receptors, involved in hepatocytes cell proliferation, differentiation and metabolism. On the other hand, somatostatin receptors (SSTRs) are exclusively present on the biliary tract. Importantly, the GH-IGF-SST system components have been indicated as regulators of hepatocarcinogenesis. Reduction of GH binding affinity to GH receptor, decreased serum IGF1 and increased serum IGF2 production, overexpression of IGF1 receptor, loss of function of IGF2 receptor and appearance of SSTRs are frequently observed in human HCC. In particular, recently, many studies have evaluated the correlation between increased levels of IGF1 receptors and liver diseases and the oncogenic role of IGF2 and its involvement in angiogenesis, migration and, consequently, in tumour progression. SST directly or indirectly influences tumour growth and development through the inhibition of cell proliferation and secretion and induction of apoptosis, even though SST role in hepatocarcinogenesis is still opened to argument. This review addresses the present evidences suggesting a role of the GH-IGF-SST system in the development and progression of HCC, and describes the therapeutic perspectives, based on the targeting of GH-IGF-SST system, which have been hypothesised and experimented in HCC.

Biochemical/metabolic changes associated with hepatocellular carcinoma development in mice

Hepatocellular carcinoma (HCC) is the third leading cause of cancer-related mortality after lung and stomach cancers. This work was undertaken to investigate some of the biochemical mediators/pathways associated with or implicated in the pathogenesis of HCC. Male albino mice were classified into two groups: normal control group and HCC group. Early stage HCC was induced by injection of diethylnitrosamine (DEN) i.p. 200 mg/kg as a single dose, and after 2 weeks, the mice were given i.p. injection of thioacetamide (TAA) 100 mg/kg twice per week for 4 weeks. Mice were left for further 2 weeks without any treatment, after which, mice were sacrificed; blood and liver samples were collected. Serum was used for determination of activities of glucose-6-phosphate dehydrogenase (G6PDH) and aldolase as well as levels of insulin-like growth factor-1 (IGF-1) and epithelial cadherin (E-cadherin). One portion of the liver was used for histopathological examination and immunohistochemical staining of the tumor suppressor p53 protein. Another portion of the liver was used for determination of citrate synthase activity. Induction of HCC in mice resulted in significant increase in G6PDH and aldolase activities, and E-cadherin level, but significant decrease in IGF-1. HCC mice group showed moderate expression of p53 protein. These results suggest that the molecular pathogenesis of HCC in mice involves reduction of serum level of IGF-1 and increased serum level of E-cadherin accompanied by dysregulation of p53 protein expression. HCC was also associated with reprogrammed metabolic profile shifted toward increased glycolysis and lipogenesis.

Inactivation of p27kip1 promotes chemical hepatocarcinogenesis through enhancing inflammatory cytokine secretion and STAT3 signaling activation

Although the expression of p27 has been regarded as a prognostic parameter in human liver cancer since the implication of decreased p27 expression levels in the genesis and progression of hepatocellular carcinoma (HCC), the molecular mechanism linking p27 deficiency and HCC development is still unclear. Here, we report an increase in tumorigenesis and progression as well as an enhanced inflammatory response in p27 deficient mice (p27(-/-)) and hypothesize the possible mechanism. We show that p27(-/-) mice display increased proliferation and decreased apoptosis of tumor cells, accompanied by an increase in the serum inflammatory cytokines IL-6 and TNF-α. Furthermore, our data indicated that the increased number and signal transducers and activator of transcription 3 (STAT3) phosphorylation status of infiltrated inflammatory cells was accompanied by increased IL-6 and TNF-α mRNA levels in tumor and normal liver tissue in the p27(-/-) mice. Moreover, using tumor cell and splenocytes co-culture and tumor homologous transplantation, we validated our hypothesis in vitro and in vivo. Collectively, these data demonstrate that the loss of p27 promotes carcinogens-induced HCC genesis and progression via the elevation of inflammatory cytokines and the augmented activation of STAT3 signaling in tumor cells and infiltrated inflammatory cells. Altogether, the loss of the cyclin kinase inhibitor p27, traditionally regarded as a consequence of DNA damage, can in turn promote HCC progression through enhancing the inflammatory response, potentially representing a promising therapeutic target in the prevention of HCC genesis and progression.

Increased miR-221 expression in hepatocellular carcinoma tissues and its role in enhancing cell growth and inhibiting apoptosis in vitro

Background

MiR-221 is over-expressed in human hepatocellular carcinoma (HCC), but its clinical significance and function in HCC remains uncertain. The aim of the study was to investigate the relationship between miR-221 overexpression and clinicopathological parameters in HCC formalin-fixed paraffin-embedded (FFPE) tissues, and the effect of miR-221 inhibitor and mimic on different HCC cell lines in vitro.

Methods

MiR-221 expression was detected using real time RT-qPCR in FFPE HCC and the adjacent noncancerous liver tissues. The relationship between miR-221 level and clinicopathological features was also analyzed. Furthermore, miR-221 inhibitor and mimic were transfected into HCC cell lines HepB3, HepG2 and SNU449. The effects of miR-221 on cell growth, cell cycle, caspase activity and apoptosis were also investigated by spectrophotometry, fluorimetry, fluorescence microscopy and flow cytometry, respectively.

Results

The relative expression of miR-221 in clinical TNM stages III and IV was significantly higher than that in the stages I and II. The miR-221 level was also upregulated in the metastatic group compared to the nonmetastatic group. Furthermore, miR-221 over-expression was related to the status of tumor capsular infiltration in HCC clinical samples. Functionally, cell growth was inhibited, cell cycle was arrested in G1/S-phase and apoptosis was increased by miR-221 inhibitor in vitro. Likewise, miR-221 mimic accelerated the cell growth.

Conclusions

Expression of miR-221 in FFPE tissues could provide predictive significance for prognosis of HCC patients. Moreover, miR-221 inhibitor could be useful to suppress proliferation and induce apoptosis in HCC cells. Thus miR-221 might be a critical targeted therapy strategy for HCC.

The silencing of Pokemon attenuates the proliferation of hepatocellular carcinoma cells in vitro and in vivo by inhibiting the PI3K/Akt pathway

Pokemon (POK erythroid myeloid ontogenic factor), which belongs to the POK protein family, is also called LRF, OCZF and FBI-1. As a transcriptional repressor, Pokemon assumes a critical function in cellular differentiation and oncogenesis. Our study identified an oncogenic role for Pokemon in human hepatocellular carcinoma (HCC). We successfully established human HepG2 and Huh-7 cell lines in which Pokemon was stably knocked down. We demonstrated that Pokemon silencing inhibited cell proliferation and migration. Pokemon knockdown inhibited the PI3K/Akt and c-Raf/MEK/ERK pathways and modulated the expression of various cell cycle regulators in HepG2 and Huh-7 cells. Therefore, Pokemon may also be involved in cell cycle progression in these cells. We confirmed that Pokemon silencing suppresses hepatocellular carcinoma growth in tumor xenograft mice. These results suggest that Pokemon promotes cell proliferation and migration in hepatocellular carcinoma and accelerates tumor development in an Akt- and ERK-signaling-dependent manner.

Expression of ADAMTS-1, ADAMTS-4, ADAMTS-5 and TIMP3 by hepatocellular carcinoma cell lines

Little is known about the expression or role of ADAMTS-1, -4 and -5 and their endogenous inhibitor TIMP3 in the liver in physiological and pathological conditions. Their expression was, therefore, investigated in the hepatocellular carcinoma cell lines HepG2 and HuH-7 using qRT-PCR and western blotting, and their cellular localisation by immunocytochemistry. Cytokine treatments were used to assess mRNA and protein modulation. ADAMTS-1, -4, -5 and TIMP3 mRNA and protein were detected in both HepG2 and HuH-7 cells. IL-1β and IL-6 treatments significantly modulated ADAMTS-1 mRNA expression and IL-1β treatment ADAMTS-4 mRNA expression in HepG2 cells. Modulations of mRNA by ≥ 5-fold did not translate to increased protein expression. This study showed that ADAMTS-1, -4, -5 and TIMP3 were expressed at differential levels in hepatocellular carcinoma cell lines. The pro-inflammatory cytokines IL-1β, TNF-α or IL-6 induced changes in mRNA expression, although these did not translate to the protein level.

Pharmacological inhibition of Frizzled-7 displays anti-tumor properties in hepatocellular carcinoma

BACKGROUND & AIMS

We previously reported the frequent overexpression of the FZD7 membrane receptor in hepatocellular carcinoma (HCC) and its role for controlling cancer phenotype. Herein, this study aimed at assessing the anticancer properties of compounds inhibiting FZD7 activity by disrupting its binding with the cytosolic Dishevelled (DVL) adaptator.

METHODS

We have designed small interfering peptides (RHPDs) that are able to enter within cells and to competitively antagonize the binding of FZD7 to the PDZ domain of DVL. Their anti-neoplastic properties were assessed in vitro on a panel of human HCC cell lines and in vivo on the SV40-TAg transgenic mouse model of HCC.

RESULTS

We have shown that RHPDs decrease cell viability via apoptosis depending on their affinity for PDZ, with a therapeutic index between cancerous and non-cancerous cells. RHPD properties were linked to β-catenin degradation and PKCδ activation. In transgenic mice, intra-tumor injection of RHPDs inhibited HCC progression.

CONCLUSIONS

We have completed a proof-of-concept showing that in vitro and in vivo the pharmacological inhibition of FZD7 displays anti-cancerous properties against HCC. The mechanisms can involve β-catenin and PKCδ modulations. Further studies are warranted to design protocols showing the compatibility with systemic in vivo applications.