Direct evidence that hepatocyte growth factor-induced invasion of hepatocellular carcinoma cells is mediated by urokinase

A Paradigm Shift in Primary Liver Cancer Therapy Utilizing Genomics, Molecular Biomarkers, and Artificial Intelligence

Primary liver cancer is the sixth most common cancer worldwide and the third leading cause of cancer-related death. Conventional therapies offer limited survival benefit despite improvements in locoregional liver-directed therapies, which highlights the underlying complexity of liver cancers. This review explores the latest research in primary liver cancer therapies, focusing on developments in genomics, molecular biomarkers, and artificial intelligence. Attention is also given to ongoing research and future directions of immunotherapy and locoregional therapies of primary liver cancers.

Hepatic Stellate Cells in Liver Tumor

Hepatocellular carcinoma and intrahepatic cholangiocarcinoma are the most common types of primary liver cancers. Moreover, the liver is the second most frequently involved organ in cancer metastasis after lymph nodes. The tumor microenvironment is crucial for the development of both primary and secondary liver cancers. The hepatic microenvironment consists of multiple cell types, including liver sinusoidal endothelial cells, Kupffer cells, natural killer cells, liver-associated lymphocytes, and hepatic stellate cells (HSCs). The microenvironment of a normal liver changes to a tumor microenvironment when tumor cells exist or tumor cells migrate to and multiply in the liver. Interactions between tumor cells and non-transformed cells generate a tumor microenvironment that contributes significantly to tumor progression. HSCs play a central role in the tumor microenvironment crosstalk. As this crosstalk is crucial for liver carcinogenesis and liver-tumor development, elucidating the mechanism underlying the interaction of HSCs with the tumor microenvironment could provide potential therapeutic targets for liver cancer.

MicroRNAs Involved in Metastasis of Hepatocellular Carcinoma: Target Candidates, Functionality and Efficacy in Animal Models and Prognostic Relevance

Hepatocellular carcinoma (HCC) is responsible for the second-leading cancer-related death toll worldwide. Although sorafenib and levantinib as frontline therapy and regorafenib, cabazantinib and ramicurimab have now been approved for second-line therapy, the therapeutic benefit is in the range of only a few months with respect to prolongation of survival. Aggressiveness of HCC is mediated by metastasis. Intrahepatic metastases and distant metastasis to the lungs, lymph nodes, bones, omentum, adrenal gland and brain have been observed. Therefore, the identification of metastasis-related new targets and treatment modalities is of paramount importance. In this review, we focus on metastasis-related microRNAs (miRs) as therapeutic targets for HCC. We describe miRs which mediate or repress HCC metastasis in mouse xenograft models. We discuss 18 metastasis-promoting miRs and 35 metastasis-inhibiting miRs according to the criteria as outlined. Six of the metastasis-promoting miRs (miR-29a, -219-5p, -331-3p, 425-5p, -487a and -1247-3p) are associated with unfavourable clinical prognosis. Another set of six down-regulated miRs (miR-101, -129-3p, -137, -149, -503, and -630) correlate with a worse clinical prognosis. We discuss the corresponding metastasis-related targets as well as their potential as therapeutic modalities for treatment of HCC-related metastasis. A subset of up-regulated miRs -29a, -219-5p and -425-5p and down-regulated miRs -129-3p and -630 were evaluated in orthotopic metastasis-related models which are suitable to mimic HCC-related metastasis. Those miRNAs may represent prioritized targets emerging from our survey.

Metalloproteinase meprin α regulates migration and invasion of human hepatocarcinoma cells and is a mediator of the oncoprotein Reptin

Hepatocellular carcinoma is associated with a high rate of intra-hepatic invasion that carries a poor prognosis. Meprin alpha (Mep1A) is a secreted metalloproteinase with many substrates relevant to cancer invasion. We found that Mep1A was a target of Reptin, a protein that is oncogenic in HCC. We studied Mep1A regulation by Reptin, its role in HCC, and whether it mediates Reptin oncogenic effects.

MepA and Reptin expression was measured in human HCC by qRT-PCR and in cultured cells by PCR, western blot and enzymatic activity measurements. Cell growth was assessed by counting and MTS assay. Cell migration was measured in Boyden chambers and wound healing assays, and cell invasion in Boyden chambers.

Silencing Reptin decreased Mep1A expression and activity, without affecting meprin β. Mep1A, but not meprin β, was overexpressed in a series of 242 human HCC (2.04 fold, p < 0.0001), and a high expression correlated with a poor prognosis. Mep1A and Reptin expressions were positively correlated (r = 0.39, p < 0.0001). Silencing Mep1A had little effect on cell proliferation, but decreased cell migration and invasion of HuH7 and Hep3B cells. Conversely, overexpression of Mep1A or addition of recombinant Mep1A increased migration and invasion. Finally, overexpression of Mep1A restored a normal cell migration in cells where Reptin was depleted.

Mep1A is overexpressed in most HCC and induces HCC cell migration and invasion. Mep1A expression is regulated by Reptin, and Mep1A mediates Reptin-induced migration. Overall, we suggest that Mep1A may be a useful target in HCC.

Systematic analysis of the molecular mechanism of microRNA-124 in hepatoblastoma cells

The present study aimed to identify the molecular mechanisms of microRNA-124 (miRNA-124/miR-124) in hepatoblastoma. The GSE6207 microarray dataset, obtained from the Gene Expression Omnibus database, included samples extracted from HepG2 cells transfected with miR-124 duplex (the experimental group) or negative control (the control group) at 4, 8, 16, 24, 32, 72 and 120 h after transfection. Differentially expressed genes (DEGs) were screened between the two groups. miR-124 activity was inferred based on the expression of its target genes. The mRNAs targeted by miR-124 were predicted and a miR-124-target mRNA network was constructed. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analyses were performed for the target genes. The number of DEGs was highest at 72 h. The experimental group had higher miR-124 activity than that of the control group at 4, 8, 16, 24 and 120 h. Small GTPase-mediated signal transduction and Ras protein signal transduction were significant GO terms enriched with syndecan binding protein (SDCBP), Ras homolog family member G (RHOG) and Rho-GDP dissociation inhibitor-α (ARHGDIA). Regulation of actin cytoskeleton, D-glutamine and D-glutamate metabolism, and axon guidance were significant pathways. Axon guidance pathway was associated with neuropilin (NRP1), MET proto-oncogene, receptor tyrosine kinase (MET) and semaphorin 7A, GPI membrane anchor (SEMA7A). Small GTPase-mediated signal transduction, Ras protein signal transduction, regulation of actin cytoskeleton pathway, D-glutamine and D-glutamate metabolism pathway, axon guidance pathway, SDCBP, RHOG, ARHGDIA, NRP1, SEMA7A, and MET may be implicated in the underlying mechanisms of miR-124 overexpression in hepatoblastoma.

MiRNA199a-3p suppresses tumor growth, migration, invasion and angiogenesis in hepatocellular carcinoma by targeting VEGFA, VEGFR1, VEGFR2, HGF and MMP2

Increasing significance of tumor-stromal interaction in development and progression of cancer implies that signaling molecules in the tumor microenvironment (TME) might be the effective therapeutic targets for hepatocellular carcinoma (HCC). Here, the role of microRNA miR-199a-3p in the regulation of TME and development of HCC has been investigated by several in vitro and in vivo assays. Expression of miR-199a-3p was observed significantly low in HCC tissues and its overexpression remarkably inhibited in vivo tumor growth and metastasis to lung in NOD-SCID mice. In vitro restoration of miR-199a-3p expression either in endothelial cells (ECs) or in cancer cells (CACs) significantly diminished migration of ECs in co-culture assay. Again incubation of miR-199a-3p transfected ECs with either conditioned media (CM) of CACs or recombinant VEGF has reduced tube formation, in ECs and it was also dropped upon growth in CM of either anti-VEGF antibody-treated or miR-199a-3p-transfected CACs. In addition, bioinformatics and luciferase-reporter assays revealed that miR-199a-3p inhibited VEGF secretion from CACs and VEGFR1 and VEGFR2 expression on ECs and thus restricted cross talk between CACs and ECs. Again, restoration of miR-199a-3p in hepatic stellate cells (HSCs) reduced migration and invasion of CACs in co-culture assay, while it was enhanced by the overexpression of HGF suggesting miR-199a-3p has hindered HSC-CACs cross talk probably by inhibiting HGF and regulating matrix metalloproteinase MMP2, which were found as targets of miR-199a-3p subsequently by luciferase-reporter assay and gelatin zymography, respectively. Thus, these findings collectively highlight that miR-199a-3p restricts metastasis, invasion and angiogenesis in HCC and hence it may be considered as one of the powerful effective therapeutics for management of HCC patients.

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.

Insulin-like growth factor-1 receptor is associated with better prognosis in classical Hodgkin's lymphoma: Correlation with MET expression

The purpose of this study was to examine the prognostic significance of insulin-like growth factor-1 receptor (IGF-1R) expression alone and in relation to the expression of the MET- receptor and the MET-homologous receptor RON, in classical Hodgkin's lymphoma (cHL). Tumour samples from patients with cHL (n = 202; median age 37.5 years) were analysed retrospectively for IGF-R1, MET or RON expression by immunohistochemistry using tissue microarrays. The median follow-up time was 3.7 years (range, 0.1-20 years). Twenty-nine patients (14.3%) expressed IGF-1R protein in Hodgkin/Reed-Sternberg (HRS) cells, which was associated with a better overall survival (OS) (P = 0.036). IGF-1R expression was closely associated with MET receptor expression and low level of lactate dehydrogenase. In patients with cHL receiving doxorubicin, bleomycin, vinblastine and dacarbazine, those expressing IGF-1R showed a trend towards better OS and event-free survival than IGF-1R-negative patients (P = 0.129 and P = 0.115 respectively), but statistical significance was not reached. This study suggests that IGF-1R expression could be associated with better clinical outcome in cHL but is significantly associated with the expression of MET receptor.

Naringenin suppresses TPA-induced tumor invasion by suppressing multiple signal transduction pathways in human hepatocellular carcinoma cells

Naringenin, a common dietary flavonoid abundantly present in fruits and vegetables, is believed to possess strong anti-proliferative properties and the ability to induce apoptosis in hepatoma cell lines. However, there are no reports describing its effects on the invasion and metastasis of hepatoma cell lines, and the detailed molecular mechanisms of its effects are still unclear. In this study, we investigated the mechanisms underlying naringenin-mediated inhibition of 12-O-Tetradecanoylphorbol-13-acetate (TPA)-induced cell invasion and inhibition of secreted and cytosolic MMP-9 production in human hepatoma cells (HepG2, Huh-7, and HA22T) and murine embryonic liver cells (BNL CL2). Naringenin suppressed MMP-9 transcription by inhibiting activator protein (AP)-1 and nuclear factor-κB (NF-κB) activity. It suppressed TPA-induced AP-1 activity through inhibiting the phosphorylation of the extracellular signal-related kinase (ERK) and c-Jun N-terminal kinase (JNK) signaling pathways, and it suppressed TPA-induced inhibition of NF-κB nuclear translocation through IκB. Additionally, it suppressed TPA-induced activation of ERK/phosphatidylinositol 3-kinase/Akt upstream of NF-κB and AP-1. These data suggest that naringenin suppresses the invasiveness and metastatic potential of hepatocellular carcinoma (HCC) by inhibiting multiple signal transduction pathways.

Augmented expression of urokinase plasminogen activator and extracellular matrix proteins associates with multiple myeloma progression

Multiple myeloma (MM) represents a B cell malignancy, characterized by a monoclonal proliferation of malignant plasma cells. Interactions between tumor cells and extracellular matrix (ECM) are of importance for tumor invasion and metastasis. Protein levels of urokinase plasminogen activator (uPA) and fibulin 1, nidogen and laminin in plasma and serum respectively and mRNA levels of these molecules in peripheral blood mononuclear cells were determined in 80 subjects by using ELISA and quantitative PCR and data was analyzed with severity of disease. Pearson correlation was determined to observe interrelationship between different molecules. A statistical significant increase for ECM proteins (laminin, nidogen and fibulin 1) and uPA at circulatory level as well as at mRNA level was observed compared to healthy controls. The levels of these molecules in serum might be utilized as a marker of active disease. Significant positive correlation of all ECM proteins with uPA was found and data also correlates with severity of disease. Strong association found between ECM proteins and uPA in this study supports that there might be interplay between these molecules which can be targeted. This study on these molecules may help to gain insight into processes of growth, spread, and clinical behavior of MM.

Genistein inhibits tumor invasion by suppressing multiple signal transduction pathways in human hepatocellular carcinoma cells

BACKGROUND

Genistein (Gen) exhibits anti-mutagenic and anti-metastatic activities in hepatoma cell lines. Gen has suppressive effects on tumor growth and angiogenesis in nude mice. Gen suppresses the enzymatic activity of matrix metalloproteinase (MMP)-9; however, the mechanism underlying its anti-invasive activity on hepatocellular carcinoma (HCC) cells is unclear.

METHODS

In this study, the possible mechanisms underlying Gen-mediated reduction of 12-O-Tetradecanoylphorbol-13-acetate (TPA)-induced cell invasion and inhibition of secreted and cytosolic MMP-9 production in human hepatoma cells (HepG2, Huh-7, and HA22T) and murine embryonic liver cells (BNL CL2) were investigated.

RESULTS

Gen suppressed MMP-9 transcription by inhibiting activator protein (AP)-1 and nuclear factor-κ B (NF-κB) activity. Gen suppressed TPA-induced AP-1 activity through inhibitory phosphorylation of extracellular signal-related kinase (ERK) and c-Jun N-terminal kinase (JNK) signaling pathways, and TPA-stimulated inhibition of NF-κB nuclear translocation through IκB inhibitory signaling pathways. Moreover, Gen suppressed TPA-induced activation of ERK/phosphatidylinositol 3-kinase/Akt upstream of NF-κB and AP-1.

CONCLUSIONS

Gen and its inhibition of multiple signal transduction pathways can control the invasiveness and metastatic potential of HCC.

Rationale for clinical trials of coagulation: reactive drugs in hepatocellular carcinoma

Evidence for the regulation of cancer growth by components of the blood coagulation mechanism provides abundant opportunity for the development of novel hypotheses for the experimental treatment of malignancy. Information available on the heterogeneity in mechanisms of interaction between various cancer cell types, and procoagulant and fibrinolytic pathways, platelets, glycosaminoglycan-regulated growth factors and cell-adhesion molecules indicates that insightful clinical trial design may allow targeting of individual cancer cell types with agents capable of intercepting mechanisms of growth control that are relevant to specific tumor types. This paper reviews the evidence that the common anticoagulant, heparin, inhibits hepatocellular carcinoma cell proliferation and hepatocellular carcinoma tumor dissemination in experimental animals. Clinical trials of heparin performed to date have shown increased tumor response rates and survival in other tumor types. Expression of urokinase-type plasminogen activator by hepatocellular carcinoma cells enhances tumor cell proliferation, motility, invasiveness and metastatic dissemination. Inhibition of the urokinase-type plasminogen activator/plasmin system by protease inhibitors such as aprotinin (Trasylol, Bayer) have shown improvement in the clinical course of certain tumor types. These data suggest that drugs that are well-known in the field of vascular medicine may find a role in the treatment of hepatocellular carcinoma, a common tumor type that has resisted containment by other means.

The role of the myofibroblast in tumor stroma remodeling

Since its first description in wound granulation tissue, the myofibroblast has been recognized to be a key actor in the epithelial-mesenchymal cross-talk that plays a crucial role in many physiological and pathological situations, such as regulation of prostate development, ventilation-perfusion in lung alveoli or organ fibrosis. The presence of myofibroblasts in the stroma reaction to epithelial tumors is well established and many data are accumulating which suggest that the stroma compartment is an active participant in tumor onset and/or evolution. In this review we summarize the evidence in favor of this concept, the main mechanisms that regulate myofibroblast differentiation and function, as well as the biophysical and biochemical factors possibly involved in epithelial-stroma interactions, using liver carcinoma as main model, in view of achieving a better understanding of tumor progression mechanisms and of tools directed toward stroma as eventual therapeutic target.

Signaling networks in human hepatocarcinogenesis--novel aspects and therapeutic options

Hepatocellular carcinoma (HCC) represents one of the most common human malignancies with poor prognosis. Because therapeutic strategies are insufficient for most HCC patients, there is a great need to determine the central molecular mechanisms and pathways in order to derive novel targets for systemic therapy. There is vast evidence that not only the dysregulation of distinct signaling cascades, but also their interactions at different levels, affect tumor cell function. Through these interactions, the effects of pathways can be increased, and even new tumor-supporting qualities acquired that further facilitate HCC progression. Although several approaches for the modulation of these relevant pathways are under development, future therapeutic strategies should take into account that oncogenic stimuli cannot be understood in a monodimensional manner. In order to avoid escape mechanisms during therapy, strategies based on comprehensive knowledge of the interactive regulatory network in hepatocarcinogenesis are necessary.

Berberine inhibits human hepatoma cell invasion without cytotoxicity in healthy hepatocytes

Conventional chemotherapy fails to cure metastatic hepatoma mainly due to its high hepatotoxicity. Many plant-derived agents have been accepted to effectively inhibit hepatoma cell invasion. However, the investigation that whether effectual plant-derived agents against invasive hepatoma cells exert unexpected cytotoxicity in healthy hepatocytes has been ignored. This study demonstrated that berberine exhibited significant cytotoxicity in HepG2 cells mainly through upregulation of reactive oxygen species (ROS) production but was ineffective in normal Chang liver cells. Berberine exerted anti-invasive effect on HepG2 cells through suppression of matrix metalloproteinase-9 (MMP-9) expression. Moreover, berberine could significantly inhibit the activity of PI3K-AKT and ERK pathways. Combination treatment of ERK pathway inhibitor PD98059 or AKT pathway inhibitor LY294002 and berberine could result in a synergistic reduction on MMP-9 expression along with an inhibition of cell invasion. Enhancement of ROS production by berberine had no influence on its suppressive effects on the activity of PI3K-AKT and ERK pathways, as well as MMP-9 expression and HepG2 cell invasion. In conclusion, our results suggest that berberine may be a potential alternative against invasive hepatoma cells through PI3K-AKT and ERK pathways-dependent downregulation of MMP-9 expression. This study also provides a previously neglected insight into the investigation of plant-derived agents-based therapy against tumor invasion with the consideration of damage to healthy cells.

Expression of hepatocyte growth factor activator inhibitor type 1 in human hepatocellular carcinoma and postoperative outcomes

BACKGROUND

Hepatocyte growth factor activator inhibitor type 1 (HAI-1), one of the Kunitz-type serine protease inhibitors, has an important role in cancer progression through regulation of the activity of hepatocyte growth factor. HAI-1 is expressed in hepatocellular carcinoma (HCC) to various degrees. Investigation of the relationship between HAI-1 expression and clinicopathological features of HCC may contribute to improved treatment outcomes for HCC through understanding the mechanism of tumor progression or improvement in the prediction of tumor malignancy.

METHODS

The study included 121 HCC patients treated surgically from 1996 to 2005. We performed immunohistological examination for HAI-1 in resected HCC specimens by use of anti-human HAI-1 monoclonal antibody. Clinicopathological features, including postoperative overall survival (OS) and disease-free survival (DFS) rates, were compared between the immunoreaction positive and negative groups.

RESULTS

The immunoreaction positive group included 38 patients (31%), and the negative group included 83 patients (69%). OS and DFS rates were significantly higher in the HAI-1 negative group than in the positive group. HAI-1 positivity related to multiplicity, vascular invasion, and characteristics of advanced tumor stage. In multivariate analysis, expression of HAI-1 was a significant independent prognostic tumor factor.

CONCLUSIONS

Expression of HAI-1 in HCC cells is associated with poor prognosis for HCC patients. HAI-1 may be important in HCC progression and may be a new prognostic factor for HCC.

Plasmin plays a key role in the regulation of profibrogenic molecules in hepatic stellate cells

BACKGROUND

Plasmin role in transforming growth factor-beta (TGF-beta)-responsive gene regulation remains to be elucidated. Also, plasmin action on co-repressor Ski-related novel protein N (SnoN) and differential activation of matrix metalloproteinases (MMPs) are unknown. Thus, the role of plasmin on profibrogenic molecule expression, SnoN transcriptional kinetics and gelatinase activation was investigated.

METHODS

Hepatic stellate cells (HSC) were transduced with adenovirus-mediated human urokinase plasminogen activator (Ad-huPA) (4 x 10(9) viral particles/ml). Overexpression of urokinase plasminogen activator and therefore of plasmin, was blocked by tranexamic acid (TA) in transduced HSC. Gene expression was monitored by reverse transcriptase polymerase chain reaction. HSC-free supernatants were used to evaluate MMP-2 and MMP-9 by zymography. SnoN, TGF-beta and tissue inhibitor of metalloproteinase (TIMP)-1 were analysed by Western blot. Plasmin and SnoN expression kinetics were evaluated in bile duct-ligated (BDL) rats.

RESULTS

Plasmin overexpression in Ad-huPA-transduced HSC significantly decreased gene expression of profibrogenic molecules [alpha1(I)collagen 66%, TIMP-1 59%, alpha-smooth muscle actin 90% and TGF-beta 55%]. Interestingly, both SnoN gene and protein expression increased prominently. Plasmin inhibition by TA upregulated the profibrogenic genes, which respond to TGF-beta-intracellular signalling. In contrast, SnoN mRNA and protein dropped importantly. Plasmin-activated MMP-9 and MMP-2 in HSC supernatants. Taken together, these findings indicate that MMP-9 activation is totally plasmin dependent. SnoN levels significantly decreased in cholestatic-BDL rats (82%) as compared with control animals. Interestingly, hepatic plasmin levels dropped 46% in BDL rats as compared with control.

CONCLUSION

Plasmin plays a key role in regulating TGF-beta-responding genes. In particular, regulation of TGF-beta-co-repressor (SnoN) is greatly affected, which suggests SnoN as a cardinal player in cholestasis-induced fibrogenesis.

Proteinases and their inhibitors in liver cancer

Proteinases are known to be involved in many cancer-related processes, particularly in the breakdown of extracellular matrix barriers in the course of tumor invasion and metastasis. In this review we summarize the current knowledge about the role of the most important matrix-degrading proteinases (cathepsins, matrix metalloproteinases, plasmin/plasminogen activators) and their respective inhibitors in liver cancer progression and metastasis.

Dietary trans-resveratrol bioavailability and effect on CCl4-induced liver lipid peroxidation

BACKGROUND AND AIM

Several in vitro studies have demonstrated the ability of pure trans-resveratrol (t-Res) to act as an anti-oxidant, but the scientific literature is lacking in in vivo studies dealing with dietary t-Res bioavailability in oxidative stress models. Our aim was to investigate the bioavailability of t-Res from dietary sources and its effect on an animal model of carbon tetrachloride (CCl4)-induced liver lipid peroxidation.

METHODS

Ten rats were intragastrically administered for 14 days with a grape-stalk extract determining a daily t-Res dosage of 3 mg/kg. The control group (10 rats) was daily injected with the vehicle solvent without the t-Res extract. After 1 week, the induction of liver lipid peroxidation by CCl4 injection was carried out. Serum and liver samples, at different time intervals, were collected to evaluate t-Res content, by high-performance liquid chromatography (HPLC) and liquid chromatography-mass spectometry-mass spectometry (LC-MS-MS). Liver malondialdehyde (MDA) as marker of oxidative stress was measured.

RESULTS

t-Res accumulates in the liver reaching 49.8 +/- 10.2 ng/g after 7 days and 191.8 +/- 15.3 ng/g after 14 days. No t-Res was detected in serum. The increase of MDA liver concentration due to CCl4 injection after 24 h and 1 week was reduced by 38% and a 63%, respectively, by the treatment with the t-Res extract.

CONCLUSIONS

A moderate consumption of t-Res from a dietary source resulted in a time-dose-dependent liver accumulation. It was able to counteract in vivo CCl4-induced liver lipid peroxidation thus demonstrating the hepatoprotective property of t-Res.

MEK/ERK-dependent uPAR expression is required for motility via phosphorylation of P70S6K in human hepatocarcinoma cells

Motility and invasiveness events require specific intracellular signaling cascade activations. In cancer liver cells, one of these mechanisms could involve the MAPK MEK/ERK cascade activation which has been shown over expressed and activated in hepatocellular carcinoma. To study whether the MEK/ERK cascade is involved in the motility of HCC, we examined the effect of MEK inhibitor and ERK2 silencing using monolayer wound-healing assays and fluoroblock invasion systems. Evidence was provided that the MAPK cascade is a key transduction pathway which controls HCC cells motility and invasiveness. We could disconnect proliferation to motility using mitomycin C and we established that RNAi-mediated inhibition of ERK2 led to strongly reduced cell motility. To improve our understanding, we analysed the regulation and the role of urokinase receptor (uPAR) in this process. We provided evidence that uPAR was under a MEK/ERK dependent mechanism and blocking uPAR activity using specific antagonist or inhibiting its expression by RNA interference which resulted in complete inhibition of motility. Moreover, we found in MAPK inhibited cultures and in uPAR silencing cells that p70S6K phosphorylation on residue Thr-389 was significantly reduced, whereas Ser-421/Thr-424 phosphorylation did not change. We highlighted that the FRAP/mTOR pathway did not affect motility and Thr-389 phosphorylation. Furthermore, we demonstrated that p70S6K inhibition by RNA interference completely inhibited hepatocarcinoma cell motility. Therefore, targeting uPAR and/or MEK/ERK/S6K by RNA interference could be a major therapeutic strategy for the future treatment of invasive hepatocarcinoma cells.

Osteoblasts promote migration and invasion of myeloma cells through upregulation of matrix metalloproteinases, urokinase plasminogen activator, hepatocyte growth factor and activation of p38 MAPK

Formation of osteolytic lesions is a key pathophysiological feature in multiple myeloma and results from the interaction of myeloma cells with the bone marrow microenvironment. Matrix metalloproteinases (MMPs) and plasmin may be involved in bone destruction, but their precise roles have not been clarified. Furthermore, the impact of osteoblast-related alterations on myeloma bone disease is not well understood. We addressed this complex phenomenon by applying a coculture system between myeloma cells and osteoblasts. Osteoblasts induced expression of MMP-1 and upregulated the expression of MMP-2, urokinase plasminogen activator (uPA) and hepatocyte growth factor (HGF) in myeloma cells. In turn, interaction with myeloma cells led to abundant MMP-1 expression in osteoblasts. Because MMP-1 degrades collagen, its upregulation might represent an essential mechanism contributing to bone destruction. Cocultures using primary myeloma cells confirmed the results obtained with cell lines. The mechanisms responsible for MMP-1 upregulation are mediated by both membrane-bound and soluble factors, and involve the p38 mitogen-activated protein kinase (MAPK) pathway. The interaction with osteoblasts enhances the capability of myeloma cells to transmigrate and invade through Matrigel or type I collagen. Using appropriate inhibitors, we provide evidence that these processes involve MMPs, uPA, HGF and activation of p38 MAPK.

Thrombin inhibits migration of human hepatic myofibroblasts

Several lines of data recently pointed out a role of the serine proteinase thrombin in liver fibrogenesis, but its mechanism of action is unknown. The aim of this study was to evaluate the effect of thrombin on the migration of human liver myofibroblasts. We show here that thrombin inhibits both basal migration and platelet-derived growth factor (PDGF)-BB-induced migration of myofibroblasts. By using a thrombin antagonist, a protease-activated receptor (PAR)-1 mimetic peptide, and a PAR-1 antibody, we show that this effect is dependent on the catalytic activity of thrombin and on PAR-1 activation. Thrombin's effect on basal migration was dependent on cyclooxygenase 2 (COX-2) activation because it was blocked by the COX-2 inhibitors NS-398 and nimesulide, and pharmacological studies showed that it was relayed through prostaglandin E(2) and its EP(2) receptor. On the other hand, thrombin-induced inhibition of PDGF-BB-induced migration was not dependent on COX-2. We show that thrombin inhibits PDGF-induced Akt-1 phosphorylation. This effect was consecutive to inhibition of PDGF-beta receptor activation through active dephosphorylation. Thus thrombin, through two distinct mechanisms, inhibits both basal- and PDGF-BB-induced migration of human hepatic liver myofibroblasts. The fine tuning of myofibroblast migration may be one of the mechanisms used by thrombin to regulate liver fibrogenesis.

Significance of serum hepatocyte growth factor levels in patients with hepatocellular carcinoma undergoing hepatic resection

BACKGROUND

Hepatocyte growth factor (HGF) is a potent hepatocyte mitogen and may stimulate the proliferation and invasiveness of human hepatocellular carcinoma (HCC) cells through the c-met receptor. This study evaluates the significance of serum HGF levels in patients undergoing HCC resection.

STUDY DESIGN

The peripheral and portal sera and HCC and non-tumorous tissues of 40 HCC patients, with tumor TNM stage I (n=12), II (n=17), and III (n=11) diseases, who underwent hepatic resection were prospectively collected. Serum HGF levels were determined by enzyme-linked immunosorbent assay. The c-met protein expressions were examined by immunohistochemistry. Median follow-up time was 69 months.

RESULTS

The prehepatectomy portal HGF levels (median, 622pg/mL) were significantly higher than peripheral HGF levels (564pg/mL) (P=0.026). The posthepatectomy portal HGF levels (699pg/mL) were significantly higher than prehepatectomy portal HGF levels (P<0.001). C-met expression was detected in 87.5% HCC and in 85.0% non-tumorous liver tissues. By Cox multivariate analysis, posthepatectomy portal HGF level >699pg/mL (P<0.001), multiple tumors (P=0.042), and TNM stages II (P=0.019) and III (P=0.009) were independent factors related with survival. Patients with a posthepatectomy portal HCG level >699pg/mL and with a positive c-met expression in HCC tissue have the worst survival.

CONCLUSIONS

In HCC patients, high peripheral and portal HGF serum levels related with poor prognosis after hepatic resection. Hepatocyte growth factor and c-met receptor can be targets of future HCC postoperative treatment.

Regulatory role of c-Met in insulin-like growth factor-I receptor-mediated migration and invasion of human pancreatic carcinoma cells

Pancreatic carcinoma cells overexpress the insulin-like growth factor-I (IGF-I) receptor (IGF-IR) and the hepatocyte growth factor (HGF) receptor, c-Met, which are both known to mediate tumor cell migration and invasion. We hypothesized that IGF-IR and c-Met cooperate to induce migration and invasion of human pancreatic carcinoma cells and that IGF-I-mediated migration and invasion depend on c-Met. Migration and invasion assays were done with the human pancreatic cancer cell line L3.6pl treated with PBS, IGF-I, HGF, or IGF-I plus HGF. To determine if c-Met is necessary for IGF-IR-mediated migration and invasion, c-Met was down-regulated in L3.6pl cells via adenoviral infection with a c-Met ribozyme before IGF-I treatment. IGF-I and HGF increased cell migration and invasion. Furthermore, IGF-I plus HGF had a greater than additive effect on cell migration and invasion compared with either growth factor alone. Down-regulation of c-Met nearly completely inhibited IGF-I-mediated migration and invasion. Our findings suggest that IGF-IR and c-Met cooperate to induce migration and invasion of human pancreatic carcinoma cells. Furthermore, c-Met is required for both HGF- and IGF-I-mediated migration and invasion. Elucidation of the signaling pathways that contribute to tumor progression and metastasis should provide a foundation for the development of targeted therapies for pancreatic carcinoma.

Urokinase plasminogen activator stimulates function of active forms of stromelysin and gelatinases (MMP-2 and MMP-9) in cirrhotic tissue

BACKGROUND

The authors' previous data support the notion that adenoviral-driven urokinase plasminogen activator (u-PA) expression results in reversion of experimental liver cirrhosis. The specific aim of the present study was to decipher the mechanisms involved in the regulation by endogenous/gene-delivered u-PA of matrix metalloproteinases (MMP) and related proteins engaged in degradation of excessive hepatic connective tissue.

METHODS

Tissue slices from cirrhotic rat livers were incubated with u-PA-rich supernatants from 24-h-cultured hepatic stellate cells (HSC). Matrix metalloproteinase-2, -9 and tissue inhibitor of metalloproteinases-1 (TIMP-1) were detected by western blot and biologic activity. The HSC that discontinued u-PA production were transfected with the adenovector Adu-PA and serum-free supernatants evaluated for proteolytic activity by MMP-3, MMP-2 and MMP-9. Collagen I, transforming growth factor-beta1 (TGF-beta1), plasminogen activator inhibitor-1 (PAI-1) and TIMP-1 mRNA levels were also evaluated.

RESULTS AND CONCLUSION

Endogenous u-PA from cultured HSC significantly induced the active forms of MMP-2 (68 kDa) and MMP-9 (78 kDa) in cirrhotic tissue slices. The TIMP-1 molecular forms demonstrated that u-PA pushed the presence of 'free' TIMP-1 (not complexed with MMP; 71%) in cirrhotic tissue. When non-producing u-PA-HSC were transfected with adenoviral vector coding for the functional human protein u-PA (Adhu-PA), an overactivation of MMP-3, MMP-2 and MMP-9 (800%, 48% and 100%, respectively) was found as compared with HSC transfected with control adenovirus encoding green fluorescent protein (Ad-GFP). Finally, gene expression of collagen I, TGF-beta1, PAI-1 and TIMP-1 were downregulated by Adhu-PA action as well.

Dysregulation of growth factor signaling in human hepatocellular carcinoma

Dysregulation of pleiotropic growth factors, receptors and their downstream signaling pathway components represent a central protumorigenic principle in human hepatocarcinogenesis. Especially the Insulin-like Growth Factor/IGF-1 receptor (IGF/IGF-1R), Hepatocyte Growth Factor (HGF/MET), Wingless (Wnt/beta-catenin/FZD), Transforming Growth Factor alpha/Epidermal Growth Factor receptor (TGFalpha/EGFR) and Transforming Growth Factor beta (TGFbeta/TbetaR) pathways contribute to proliferation, antiapoptosis and invasive behavior of tumor cells. This review focuses on the relevant alterations in these pathways identified in human human hepatocellular carcinomas (HCCs). Resultant functional effects are modulated by multiple cross-talks between the different signaling pathways and additional tumor-relevant factors, such as cyclooxygenase-2 and p53. Several specific strategies are currently under development such as receptor kinase inhibitors, neutralizing antibodies and antagonistic proteins, which may improve the systemic treatment of human HCCs.

Inhibitory effect of luteolin on hepatocyte growth factor/scatter factor-induced HepG2 cell invasion involving both MAPK/ERKs and PI3K–Akt pathways

Hepatocyte growth factor (HGF), also known as scatter factor (SF), and its receptor, the c-Met tyrosine kinase, play roles in cancer invasion and metastasis in a wide variety of tumor cells. Clinical observations suggest that HGF can promote metastasis of hepatoma cells while stimulating tumor invasiveness. We use HGF as an invasive inducer of human hepatoma HepG2 cells to investigate the effect of flavonoids on anti-invasion. In our preliminary study, we investigated the effect of flavonoids including luteolin, quercetin, baicalein, genistein, taxifolin and catechin on HGF-mediated migration and invasion of HepG2 cells. We found that luteolin presented the most potent potential on anti-migration and anti-invasion by Boyden chamber assay. Furthermore, luteolin inhibited HGF-induced cell scattering and cytoskeleton change such as filopodia and lamellipodia was determined by both phase-contrast and fluorescence microscopy studies. In addition, Western blotting and immunoprecipitation were performed to confirm luteolin suppressed the phosphorylation of c-Met, the membrane receptor of HGF, as well as ERK1/2 and Akt, but not JNK1/2, which is activated by HGF. Our investigation demonstrated that luteolin similar to PD98059, which acts as a specific inhibitor of MEK, an up stream kinase regulating ERK1/2, and wortmannin, a PI3K inhibitor, inhibited the invasiveness induced by HGF. In conclusion, the luteolin inhibited HGF-induced HepG2 cell invasion involving both MAPK/ERKs and PI3K-Akt pathways.

Dietary antioxidant compounds and liver health

Chronic liver damage is a widespread pathology characterized by a progressive evolution from steatosis to chronic hepatitis, fibrosis, cirrhosis, and hepatocellular carcinoma. As the oxidative stress plays a central role in liver diseases pathogenesis and progression, the use of antioxidants have been proposed as therapeutic agents, as well as drug coadjuvants, to counteract liver damage. In this work in vitro and in vivo studies, with emphasis on humans and animals experiments, have been considered and reviewed according to antioxidant typologies. Great differences emerge as far as ingested doses, bioavailability and liver ability to accumulate the various compounds. Results available up to now suggest that lycopene-rich foods could be proposed in therapeutic treatment of some liver pathologies. On the other hand contradictory results have been obtained with alpha-tocopherol, beta-carotene and trans-resveratrol. Quercetin, silymarin, esculetin and thyme and rosemary among phenolic compounds need further studies.

Nuclear factor-kappaB and liver carcinogenesis

Hepatocellular carcinoma (HCC) is the third deadliest and fifth most common human cancer worldwide. Hepatitis C virus (HCV) and hepatitis B virus (HBV) infections along with alcohol and aflatoxin B1 intake are widely recognized etiological agents in HCCs. It is anticipated that HCCs will constitute a major health problem in the next two decades because of the rising incidence of HCV infections in the US. The poor survival rate achieved by current surgical procedures and chemotherapy treatment has prompted the scientific community to gain a better understanding of the molecular events involved in hepatocarcinogenesis in order to define new targets for more effective treatment. Recent findings from several laboratories have implicated constitutive activation of the transcription factor NF-kappaB as one of the early key events involved in neoplastic progression of the liver. Data is summarized here from recently published studies illustrating a crucial role of NF-kappaB in bridging the action of growth factors and inflammation to hepatic oncogenesis. Although additional work is needed to fully understand the precise role of NF-kappaB in the regulation of the various transitions of HCC development, these new findings raise the intriguing possibility that pharmacologic inhibition of NF-kappaB in the liver could selectively eradicate malignant liver cells without affecting normal liver homeostasis.

Insulinlike growth factor-I-mediated migration and invasion of human colon carcinoma cells requires activation of c-Met and urokinase plasminogen activator receptor

OBJECTIVE

To determine whether insulinlike growth factor-I (IGF-I) and hepatocyte growth factor (HGF) cooperate to induce migration and invasion of human colorectal carcinoma (CRC) cells and whether the effects of IGF-I and/or HGF are mediated through activation of the urokinase plasminogen activator (uPA)/uPA receptor (uPAR) system, a central mediator of tumor-cell migration and invasion.

SUMMARY BACKGROUND DATA

CRC cells must invade through the basement membrane of the colon and migrate to form metastases. CRC cells are known to overexpress IGF-I receptor (IGF-IR), c-Met, and uPAR, 3 cell-surface receptors known to mediate cell migration and invasion. We hypothesized that IGF-IR and c-Met cooperate to induce migration and invasion in CRC cells and that this signaling is dependent on uPAR.

METHODS

KM12L4 human CRC cells were treated with IGF-I, HGF, or IGF-I + HGF in transwell migration and invasion chambers; cells that had migrated or invaded were counted. To determine the role of c-Met in IGF-I-induced migration and invasion, c-Met was inhibited by infection of cells with an adenovirus containing a c-Met ribozyme; transwell assays were then repeated. To determine the role of the uPA/uPAR system in IGF-I-induced CRC cell migration and invasion, transwell assays were repeated after pretreating cells with the uPA inhibitor amiloride or with neutralizing antibodies to uPA and uPAR.

RESULTS

IGF-I and HGF, alone or in combination, increased cell migration and invasion. The c-Met ribozyme inhibited IGF-I- and HGF-mediated migration and invasion, indicating that c-Met is essential for these processes. uPA and uPAR inhibition blocked IGF-I- and HGF-mediated migration and invasion, suggesting that uPAR is downstream of IGF/IGF-IR and HGF/c-Met in the signaling pathways that mediate cell migration and invasion.

CONCLUSIONS

IGF-I and HGF cooperate to induce migration and invasion of CRC cells, and c-Met and uPA/uPAR are required for IGF-I-mediated migration and invasion. In our in vitro model of CRC migration and invasion, uPA and uPAR appear to be downstream of IGF-IR and c-Met and are required for migration and invasion. Elucidation of the pathways that contribute to tumor progression and metastasis should provide a foundation for the rational development and use of targeted therapies for CRC.

Hepatocyte growth factor/c-Met signaling promotes the progression of experimental human neuroblastomas

Neuroblastoma is the most frequent solid childhood malignancy. Despite aggressive therapy, mortality is high due to rapid tumor progression to advanced stages. The molecules and mechanisms underlying poor prognosis are not well understood. Here, we report that cultured human neuroblastoma cells express the hepatocyte growth factor (HGF) and its receptor c-Met. Binding of HGF to c-Met triggers receptor autophosphorylation, indicating functional relevance of this interaction. HGF activates several downstream effectors of c-Met such as the mitogen-activated protein kinases extracellular signal-regulated kinase 1/extracellular signal-regulated kinase 2 and phospholipase C-gamma, whereas signal transducer and activator of transcription 3 is constitutively activated in neuroblastoma cells expressing c-Met. In addition, HGF is able to stimulate expression and proteolytic activity of matrix metalloproteinase-2 and tissue-type plasminogen activator in neuroblastoma cells, thereby promoting degradation of extracellular matrix components. We show that HGF stimulates invasion of neuroblastoma cells in vitro and in vivo, and it promotes the formation of angiogenic neuroblastomas in vivo. These processes can be blocked by specific inhibitors of the mitogen-activated protein kinase cascade, by inhibitors of phospholipase C-gamma, and also by the expression of a dominant negative signal transducer and activator of transcription 3 mutant. Our data provide the first evidence that the HGF/c-Met pathway is essential for invasiveness and malignant progression of human neuroblastomas. They further suggest that specific inhibitors of this pathway may be suitable as therapeutic agents to improve clinical outcome of neuroblastomas.

Improved gene transfer selectivity to hepatocarcinoma cells by retrovirus vector displaying single-chain variable fragment antibody against c-Met

Engineered retroviruses are widely used vectors for cancer gene therapy approaches. However, the ability to target cells of therapeutic interest while controlling the expression of the transferred genes would improve both the efficiency and the safety of viral vectors. In this study, we investigated the ability of a retroviral amphotropic envelope displaying single-chain variable-fragment (scFv) directed against the c-Met receptor, to target the entry of recombinant retroviruses to human hepatocarcinoma cells. Four single-chain antibody fragments directed against the c-Met receptor were generated and inserted into the viral envelope protein as an N-terminal fusion. The modified envelopes were incorporated into virus particles and one of the chimeric viruses, 3D6-Env, transduced preferentially human hepatoma cells rather than proliferating human hepatocytes. In another construct, the urokinase cleavage site was inserted between the scFv moiety and the envelope. Chimeric scFv-urokinase-Env viruses transduced hepatoma cells with a similar efficiency to that of the control virus and their infectivity in human hepatocytes remained low. These results indicate that amphotropic retroviruses with engineered envelopes to display scFv directed against the c-Met receptor can efficiently and selectively deliver genes into hepatoma cells.

Enhanced invasion of hormone refractory prostate cancer cells through hepatocyte growth factor (HGF) induction of urokinase-type plasminogen activator (u-PA)

BACKGROUND

Increased expression of the hepatocyte growth factor (HGF) receptor (MET) is associated with high-grade prostatic adenocarcinoma and metastasis. However, the mechanism through which MET signaling contributes to prostate cancer (CaP) metastasis remains unclear.

METHODS

Human PC-3 CaP cells and in vivo selected, isogeneic variant cells of increasing metastatic potential (PC-3M, PC-3M-Pro4, and PC-3M-LN4) were used to investigate the effect of HGF on CaP cell growth, protease production, and invasion. Cell-free urokinase-type plasminogen activator (u-PA) expression and function following HGF treatment were analyzed by Western blot, ELISA, and casein/plasminogen zymography. In vitro invasion stimulated by HGF was measured using Matrigel-coated invasion chambers.

RESULTS

Both mRNA and functional protein for MET were detected in each of the CaP cell lines. HGF treatment (0-40 ng/ml) weakly increase proliferation, however, HGF induced soluble u-PA protein and activity 3-fold in the metastatic variant cells. HGF significantly stimulated the invasion of highly metastatic PC-3M-LN4 cells through Matrigel and treatment with specific urokinase receptor inhibitors diminished the HGF-stimulated invasion in a dose-dependent manner.

CONCLUSIONS

These results demonstrate the biological significance of u-PA up-regulation in response to HGF in highly metastatic hormone refractory CaP cells.

Thrombin up-regulates tissue factor pathway inhibitor-2 synthesis through a cyclooxygenase-2-dependent, epidermal growth factor receptor-independent mechanism

The serine proteinase inhibitor tissue factor pathway inhibitor-2 (TFPI-2) inhibits the tissue factor-factor VIIa complex and thereby impairs factor Xa and subsequently thrombin generation. Here we show that thrombin itself up-regulates TFPI-2 mRNA and protein expression in human liver myofibroblasts, a cell type shown to express high levels of TFPI-2 (Neaud, V., Hisaka, T., Monvoisin, A., Bedin, C., Balabaud, C., Foster, D. C., Desmoulière, A., Kisiel, W., and Rosenbaum, J. (2000) J. Biol. Chem. 275, 35565-35569). This effect required thrombin catalytic activity, as shown by its abolition with hirudin. Although the thrombin effect could be mimicked by agonists of both protease-activated receptor (PAR)-1 and PAR-4, it was largely blocked by a PAR-1 blocking antibody. Transactivation of the epidermal growth factor (EGF) receptor has been reported as a common event in thrombin signaling. However, thrombin did not detectably transactivate the EGF receptor in liver myofibroblasts, and blocking the EGF receptor did not affect TFPI-2 induction. On the other hand, thrombin increased the expression of cyclooxygenase-2 (COX-2) mRNA via a MAPK-dependent pathway, and a specific COX-2 inhibitor abolished the effect of thrombin on TFPI-2 expression. Thus, thrombin, through PAR-1 signaling, up-regulates the synthesis of TFPI-2 via a MAPK/COX-2-dependent pathway. The up-regulation of TFPI-2 expression by thrombin could in turn down-regulate thrombin generation and contribute to limit blood coagulation.

Hepatitis C virus proteins do not directly trigger fibrogenic events in cultured human liver myofibroblasts

Although liver fibrosis is the major complication of hepatitis C virus (HCV) infection, the mechanisms of fibrogenesis in this setting are not completely understood. The aim of this study was to test the direct effect of HCV proteins on signalling- and fibrosis-related events in cultured human liver myofibroblasts, the effector cells of liver fibrogenesis. Cultured myofibroblasts were exposed to recombinant HCV core, a structural protein, and nonstructural proteins (NS) 3, NS 4 and NS 5. HCV proteins did not significantly increase DNA synthesis in myofibroblasts. We then examined if these proteins affected early signalling events. None of the HCV proteins affected the phosphorylation of the mitogen activated protein kinases/extracellular regulated kinases 1 and 2, or of the phosphatidylinositol 3-kinase target, Akt. HCV proteins had also no effect on intracellular calcium concentration. In other experiments, fibrogenesis-related parameters were measured. None of the HCV proteins had any effect on the secretion of type I collagen, tissue inhibitor of matrix metalloproteinases type 1, gelatinase or urokinase. Alpha-smooth muscle actin expression was also not modified. In summary, our experiments do not support a direct effect of these HCV proteins on fibrogenic cells.

HGF, MET, and matrix-related proteases in hepatocellular carcinoma, fibrolamellar variant, cirrhotic and normal liver

Fibrolamellar variant is an uncommon subcategory of hepatocellular carcinoma with a better prognostic outcome. Proteinases and growth factors that are involved in the remodeling of extracellular matrix may influence the behavior of cancers. To determine whether these factors contribute to the distinct etiologies of fibrolamellar hepatocellular carcinoma and traditional hepatocellular carcinoma, we assayed hepatocyte growth factor, the hepatocyte growth factor receptor, and two hepatocyte growth factor activators, hepatocyte growth factor activator and urokinase-type plasminogen activator, in hepatocellular carcinoma, fibrolamellar hepatocellular carcinoma, cirrhotic liver and normal liver. In addition, we examined the urokinase-type plasminogen activator receptor, the type 1 plasminogen activator inhibitor, plasmin, fibrinogen, and the type IV matrix metalloproteinases. Eighteen hepatocellular carcinomas and 11 fibrolamellar hepatocellular carcinomas were obtained as paraffin embedded sections from the University of Pittsburgh Department of Pathology. Frozen tissues from a subset of cases (9 hepatocellular carcinomas, 4 fibrolamellar hepatocellular carcinomas, 12 cirrhotic livers and 2 normal livers) were also available for analysis. Antibodies against urokinase-type plasminogen activator, urokinase-type plasminogen activator receptor, hepatocyte growth factor and hepatocyte growth factor receptor were used to analyze immunoperoxidase stained slides from the paraffin blocks. Western blot analyses using antibodies against hepatocyte growth factor, hepatocyte growth factor receptor, phosphotyrosine, hepatocyte growth factor activator, urokinase-type plasminogen activator receptor, urokinase-type plasminogen activator, plasminogen activator inhibitor-1, fibrinogen and plasmin were performed on membrane-enriched fractions from the frozen tissue, as was collagen zymography for matrix metalloproteinase-2 and matrix metalloproteinase-9. The most notable findings are as follows: hepatocyte growth factor activator was only detected in malignant tissue but not cirrhotic liver or normal liver. Although hepatocyte growth factor was detected in most samples, it was significantly elevated in 5/9 hepatocellular carcinomas. Furthermore, 8/9 fibrolamellar hepatocellular carcinomas demonstrated hepatocyte growth factor receptor levels similar to normal, whereas 8/9 hepatocellular carcinomas and 11/12 cirrhotic livers exhibited either an increase or decrease. In contrast, active matrix metalloproteinase-2, which was absent in normal liver, was elevated in fibrolamellar hepatocellular carcinoma as compared to cirrhotic liver and conventional hepatocellular carcinoma. Surprisingly, 10/12 cirrhotic livers and 2/4 fibrolamellar hepatocellular carcinomas but only 1/9 hepatocellular carcinomas were enriched for plasmin. The combined data suggest that the hepatocyte growth factor and plasmin systems tend to be operative in hepatocellular carcinoma and cirrhotic liver, more than fibrolamellar hepatocellular carcinoma. Furthermore, matrix turnover appears to be a more prominent feature of fibrolamellar hepatocellular carcinoma. These findings provide insight into the behavioral differences between hepatocellular carcinoma and the fibrolamellar variant.

Aspirin and NS-398 inhibit hepatocyte growth factor-induced invasiveness of human hepatoma cells

Nonsteroidal anti-inflammatory drugs (NSAIDs) inhibit cyclooxygenase (COX) activity and are considered to exert antitumor actions in a variety of cancer cells, although the effects are unlikely entirely due to COX inhibition. Because clinical observations suggest that hepatocyte growth factor (HGF) can promote metastasis of hepatoma cells while stimulating tumor invasiveness, we investigated the effect of aspirin and NS-398, a selective COX-2 inhibitor, on HGF-mediated invasiveness of HepG2 human hepatoma cells. HGF stimulated the invasiveness of HepG2 cells in Matrigel cell invasion assay, together with increased expression of matrix metalloproteinase (MMP) 9. Addition of aspirin or NS-398, similar to PD98059, which acts as a specific inhibitor of mitogen-activated protein kinase/extracellular signal-regulated kinase (MEK), an upstream kinase regulating extracellular signal-regulated kinase (ERK)1/2, abrogated such actions of HGF without affecting cell viability. Aspirin and NS-398, in contrast to PD98059, did not suppress ERK1/2 phosphorylation induced by HGF. However, both agents inhibited the kinase activity of ERK1/2 induced by HGF and repressed HGF-induced phosphorylation of 90-kd ribosomal S6 kinase (RSK) and Elk-1, key downstream substrates of ERK1/2, resulting in the suppression of transcriptional activity of Elk-1 as well as nuclear factor kappaB (NF-kappaB) and AP-1, which are involved in MMP-9 gene regulation. In conclusion, our results suggest that aspirin and NS-398 inhibit HGF-induced invasiveness of HepG2 human hepatoma cells through ERK1/2.

Involvement of matrix metalloproteinase type-3 in hepatocyte growth factor-induced invasion of human hepatocellular carcinoma cells

Intra-hepatic invasion is a key feature of hepatocellular carcinoma (HCC) progression. We have shown that human liver myofibroblasts induce invasion of HCC cells through Matrigel, via the secretion of hepatocyte growth factor (HGF). In our study, we investigated the role of matrix metalloproteinases (MMP) in HGF-induced HCC cells invasion. Marimastat, a synthetic MMP inhibitor, dose-dependently decreased HGF-induced invasion of HepG2 cells with a maximum of 82.7 +/- 13.3% at 20 microM. TIMP-2, a natural inhibitor, decreased invasion up to 51.2 +/- 11.2% at 200 ng/ml. To determine the target for these inhibitors, we examined MMP expression using RT-PCR. MMPs 1, 7-9 and 10 were not expressed in HepG2 cells either in the absence or in the presence of HGF. MMP-2 and MMP-13 transcripts were detected in unstimulated cells but their expression was unchanged after exposition to HGF. MMP-3 transcripts were undetectable in unstimulated HepG2 cells. They became clearly expressed in HGF-stimulated cells, however, and this was confirmed by Northern blot. By Western blot, HGF dose-dependently stimulated the secretion of pro-MMP-3 in the culture medium. The role of MMP-3 in HGF-induced invasion was directly confirmed by using an antibody to MMP-3, that blocked invasion. Finally, RT-PCR demonstrated MMP-3 expression in 10/16 human HCCs tested, but not in normal liver. In conclusion, our data demonstrate that MMPs, most likely MMP-3, mediate HGF-induced invasion of HCC cells. The in vivo expression of MMP-3 in HCC suggests a role for this protease in HCC progression.

Role of myofibroblasts at the invasion front

Tumor progression occurs within a microecosystem, where cancer cells and myofibroblasts exchange proteinases and cytokines that promote growth directly through stimulation of proliferation and survival, as well as invasion through local proteolysis of the extracellular matrix and stimulation of motility. Myofibroblasts maintain the capacity of fibroblasts to induce differentiation. Fibroblasts are the main source of tumor-associated myofibroblasts. The transition to myofibroblasts also occurs in noncancerous situations. This transition is modulated by mechanical stress and cytokines, amongst which transforming growth factor-beta. The cross-talk between cancer cells and myofibroblasts illustrates the microecosystem of tumor invasion. In order to consider myofibroblasts as a possibly new target for cancer therapy, further characterization of the molecular cross-talk between myofibroblasts and cancer cells is required.

Expression of hepatocyte growth factor activator and hepatocyte growth factor activator inhibitor type 1 in human hepatocellular carcinoma

Hepatocyte growth factor activator inhibitor type 1 (HAI-1), a Kunitz-type serine protease inhibitor for hepatocyte growth factor activator (HGFA), is responsible for proteolytic activation of hepatocyte growth factor. We examined the expression of HGFA and HAI-1 in liver tissues of chronic liver diseases including hepatocellular carcinoma (HCC). HGFA expression was detected not only in the liver tissues of chronic hepatitis and cirrhosis and in the nontumorous liver tissues surrounding HCC, but also in HCC tissues. On the other hand, none of the liver tissues of hepatitis and cirrhosis and none of the nontumorous tissues surrounding HCC were stained with anti-HAI-1. However, 35% of HCC tissues were stained with anti-HAI-1, and HAI-1 positivity increased as the histological grade decreased and as serum alpha-fetoprotein increased. Transduction of antisense HAI-1 inhibited the growth of human hepatoma cells. These results suggest the possibility that HAI-1 plays an important role in the progression of HCC.

Expression of hepatocyte growth factor in human hepatocellular carcinoma

BACKGROUND/AIMS

We have shown that hepatocyte growth factor, secreted by human liver myofibroblasts, promoted in vitro invasion of human hepatocellular carcinoma cell lines. The aim of this work was to measure hepatocyte growth factor expression in 29 human hepatocellular carcinomas and the corresponding peri-tumoral livers.

METHODS

We used reverse transcription-polymerase chain reaction, in situ hybridization, ELISA and Western blot.

RESULTS

Sixty-two of tested hepatocellular carcinomas were positive by reverse transcription-polymerase chain reaction. With in situ hybridization, a signal was found in every sample. In many cases, the signal was localized in cells labeled with an anti-smooth muscle alpka-actin antibody, while hepatocytes were mostly non-labeled. ELISA, performed in 15 pairs of hepatocellular carcinomas and surrounding livers, detected hepatocyte growth factor in every sample with wide variations. Hepatocellular carcinomas that had developed in non-cirrhotic livers contained essentially the same amount of hepatocyte growth factor as the matching non-tumoral liver. In cirrhotic livers, the hepatocyte growth factor content of the tumors was significantly lower than that of the surrounding cirrhotic livers.

CONCLUSIONS

These data indicate that hepatocyte growth factor is expressed at significant levels in every hepatocellular carcinoma tested and that its expression takes place in the stromal myofibroblasts.

Paradoxical pro-invasive effect of the serine proteinase inhibitor tissue factor pathway inhibitor-2 on human hepatocellular carcinoma cells

We have previously shown that human liver myofibroblasts promote in vitro invasion of human hepatocellular carcinoma (HCC) cells through a hepatocyte growth factor (HGF)/urokinase/plasmin-dependent mechanism. In this study, we demonstrate that myofibroblasts synthesize the serine proteinase inhibitor tissue factor pathway inhibitor-2 (TFPI-2). Despite the fact that recombinant TFPI-2 readily inhibits plasmin, we show that it potentiates HGF-induced invasion of HCC cells and is capable of inducing invasion on its own. Furthermore, HCC cells stably transfected with a TFPI-2 expression vector became spontaneously invasive. HCC cells express tissue factor and specifically factor VII. Addition of an antibody to factor VII abolished the pro-invasive effect of TFPI-2. We suggest that TFPI-2 induces invasion following binding to a tissue factor-factor VIIa complex preformed on HCC cells. Our data thus demonstrate an original mechanism of cell invasion that may be specific for liver tumor cells.

Deactivation of cultured human liver myofibroblasts by trans-resveratrol, a grapevine-derived polyphenol

Liver myofibroblasts are major actors in the development of liver fibrosis and cancer progression. There is a large interest in drugs that might deactivate these cells. Many studies have shown that the grapevine-derived polyphenol, trans-resveratrol, and other stilbenes have therapeutic potential in some diseases. In this work, we have studied the effect of grapevine polyphenols on cultured human liver myofibroblasts. We have shown that trans-resveratrol profoundly affects myofibroblast phenotype. Trans-resveratrol induced morphological modifications. It markedly reduced proliferation of myofibroblasts in a dose-dependent manner. Trans-resveratrol also decreased the expression of alpha smooth muscle actin (alpha-SMA) without affecting vimentin or beta-cytoplasmic actin expression. It decreased myofibroblast migration in a monolayer wounding assay. We also showed that trans-resveratrol inhibited the messenger RNA (mRNA) expression of type I collagen. Finally, it decreased the secretion of matrix metalloproteinase 2 (MMP-2). We conclude that trans-resveratrol can deactivate human liver myofibroblasts. In the second part of this study, we have shown that neither trans-piceid (a glycosylated analog) nor trans-piceatannol (a hydroxylated analog) reproduces trans-resveratrol effects on liver myofibroblasts. We finally show that, although trans-resveratrol decreases the proliferation of skin fibroblast and vascular smooth muscle cells, it does not affect their expression of alpha-SMA, which indicates some cell specificity.

Expression and cellular localization of the urokinase-type plasminogen activator and its receptor in human hepatocellular carcinoma

The urokinase-type plasminogen activator (uPA) and its receptor (uPAR) play an important role in tumour invasion. Previous studies have shown by RT-PCR that uPA and uPAR mRNAs are expressed in human hepatocellular carcinoma (HCC). Here, in situ hybridization, immunohistochemistry, and double immunofluorescence were used to identify the cells expressing uPA and uPAR in 26 HCCs. The results indicate that uPA and uPAR were expressed in every case, almost exclusively in stromal cells, mostly myofibroblasts and macrophages, except for rare tumoural hepatocytes expressing cytokeratin 7. These results show the important role of stromal cells of HCC in the pericellular proteolysis which facilitates cancer cell invasion.