Expression of HGF, its receptor c-met, c-myc, and albumin in cirrhotic and neoplastic human liver tissue

Zwitterionic mesoporous engineering aids peptide-dependent pattern profiling for identification of different liver diseases

Liver disease remains a global health challenge, with its incidence steadily increasing worldwide. Herein, zwitterionic mesoporous engineering was developed for the identification of different liver diseases including liver cirrhosis and liver cancer. Based on this engineering, a total of 2633 m/z signals were observed to be enriched. Notably, three key peptides were identified and showed high accuracy and precision for distinguishing the healthy and disease states, propelling the field of nanomedicine toward genuine personalized medicine.

Age independent survival benefit for patients with small hepatocellular carcinoma undergoing percutaneous cryoablation: A propensity scores matching study

Background

Hepatocellular carcinoma (HCC) is the major cause of malignancy-related deaths worldwide, and its incidence is likely to increase in the future as life expectancy increases. Therefore, the management of elderly patients with HCC has become a global issue. Aim of this study was to assess whether elderly patients with small HCC could obtain survival benefit from cryoablation (CRYO) in a real-world.

Materials and methods

From July 2007 to June 2013, 185 patients with small HCC who underwent curative-intent percutaneous CRYO. All patients were divided into three groups according to age distribution. Overall survival (OS) and tumor-free survival (TFS) were compared between among of groups before and after the 1:1 propensity score matching, respectively. Univariate and multivariate Cox analyses were performed to determine the potential relationships between variables and prognostic outcomes.

Results

One hundred and eighty-five patients (144 men, 41 women) received CRYO for small HCC, including 59 patients with age <50 years, 105 patients with age between 50 and 65 years, and 21 patients with age >65 years. The three age groups showed significant differences in the terms of underlying chronic liver disease and the number of patients with minor postoperative complications. After propensity score matching, the younger and elderly groups showed significant differences in mean OS (P=0.008) and tumor progression (P=0.050). However, no significant differences were shown in mean progression-free survival (PFS) (P=0.303). The Cox multivariate analysis showed that the Child-Pugh grade (HR=3.1, P<0.001), albumin (HR=0.85, P=0.004) and total of bilirubin (HR=1, P=0.024) were the independent prognostic factor for mean OS.

Conclusion

Our propensity-score-matched study suggested that elderly patients with small HCC can achieve acceptable prognostic outcomes with PFS similar to those of younger patients with small HCC after treatment with CRYO, while Child-Pugh grade, bilirubin and serum albumin levels were associated with the prognosis of small HCCs.

Cytokines and Hepatocellular Carcinoma: Biomarkers of a Deadly Embrace

Hepatocellular carcinoma (HCC) represents a worldwide health matter with a major care burden, high prevalence, and poor prognosis. Its pathogenesis mainly varies depending on the underlying etiological factors, although it develops from liver cirrhosis in the majority of cases. This review summarizes the role of the most interesting soluble factors as biomarkers for early diagnosis and as recommended targets for treatment in accordance with the new challenges in precision medicine. In the premalignant environment, inflammatory cells release a wide range of cytokines, chemokines, growth factors, prostaglandins, and proangiogenic factors, making the liver environment more suitable for hepatocyte tumor progression that starts from acquired genetic mutations. A complex interaction of pro-inflammatory (IL-6, TNF-α) and anti-inflammatory cytokines (TGF-α and -β), pro-angiogenic molecules (including the Angiopoietins, HGF, PECAM-1, HIF-1α, VEGF), different transcription factors (NF-kB, STAT-3), and their signaling pathways are involved in the development of HCC. Since cytokines are expressed and released during the different stages of HCC progression, their measurement, by different available methods, can provide in-depth information on the identification and management of HCC.

A Comparative Study of Serum Angiogenic Biomarkers in Cirrhosis and Hepatocellular Carcinoma

Simple Summary

The progression of liver disease is accompanied by pathological angiogenesis, a prerequisite for the development of HCC. In this paper, we analyzed the clinical significance of serum angiogenic markers VEGF, Ang-1, Ang-2, angiopoietin receptor Tie1/2, HGF, and PECAM-1 in 62 patients with liver disease, out of which 33 were diagnosed with HCC and 29 with liver cirrhosis without signs of neoplasia. Biomarkers levels were investigated as a function of “Model for End-Stage Liver Disease” (MELD) score and Fibrosis Index (FI). HCC patients showed higher HGF levels than ones with cirrhosis, while high Ang-1 levels appeared to have a protective role in HCC as well as prognostic significance; we also found a strong correlation between HGF levels, Ang-2, and VEGF levels, further supporting their role in tumor angiogenesis. Due to the complexity of angiogenesis and the small size of the study group, further investigations are widely desired especially in the era of immunotherapy and HCC-targeted anti-angiogenic drugs.

Abstract

Background: Hepatocellular carcinoma (HCC) is a global health problem associated with chronic liver disease. Its pathogenesis varies according to the underlying etiological factors, although in most cases it develops from liver cirrhosis. The disease progression is accompanied by pathological angiogenesis, which is a prerequisite that favors the development of HCC. Aims: This study aims at contributing to our understanding of the role of angiogenic factors in the progression of liver disease. For this purpose, we evaluate the clinical significance of serum angiogenic markers (VEGF, Ang-1, Ang-2, the angiopoietin receptor Tie1/2, HGF, and PECAM-1) first in cirrhotic and HCC patients separately, and then comparing cirrhotic patients with and without HCC. Materials and Methods: We enrolled 62 patients, out of whom 33 were diagnosed with HCC and 29 with liver cirrhosis without signs of neoplasia. Patients underwent venous blood sampling before and after receiving treatments for the diagnosed disease. Serum markers were evaluated using ELISA assays for Tie1 and the Bio-Plex Multiplex system for the remaining ones. Biomarker levels were investigated as a function of clinical scores for disease staging (MELD and Fibrosis Index, FI). Results: In cirrhotic patients, Ang-1 and Ang-2 correlate with MELD (ρ_Ang-1 = −0.73, p = 2E−5) and FI (ρ_Ang-1 = −0.52, p = 7E−3, ρ_Ang-2 = 0.53, p = 3E−3). A reduction of Ang-2 levels (p = 0.047) and of the Ang-2/Ang-1 ratio (p = 0.031) is observed in cirrhotic patients diagnosed with viral hepatitis after antiviral treatments. In HCC patients, Ang-1 negatively correlates with FI (ρ = −0.63, p = 1E−4), and PECAM-1 positively correlates with MELD (ρ = 0.44, p = 0.01). A significant Ang-1 reduction was observed in deceased patients during the study compared to ones who survived (p = 0.01). In HCC patients, VEGF levels were increased after tumor treatment (p = 0.037). Notably, HGF levels in cirrhotic patients with HCC are significantly raised (p = 0.017) compared to that in those without HCC. Conclusions: Our results suggest that serum angiogenic markers, with emphasis on Ang-1/2, can contribute to the development of quantitative tools for liver disease staging and therapy monitoring. The comparison between cirrhotic patients with and without HCC suggests that HGF levels are potentially useful for monitoring the insurgence of HCC after a cirrhosis diagnosis. High Ang-1 levels in HCC patients appear to have a protective role as well as prognostic significance.

Hepatocyte growth factor mediates a novel form of hepatic stem/progenitor cell-induced tolerance in a rat xenogeneic liver rejection model

We have previously identified novel neural/glial antigen 2-expressing hepatic stem/progenitor cells (NG2+ HSPs) that are beneficial for tissue repair by inhibiting the immune cell response. In this in vivo study, we investigated the use of hepatocyte growth factor (HGF)-secreting NG2+ HSPs as a tolerogen in the well-established Syrian golden hamster (SGH) to Lewis (LEW) xenogeneic rat acute liver rejection (ARJ) model. Liver and blood cells were collected for histology and functional analyses using immunofluorescence staining, western blot, ELISA, and TUNEL assays. All recipient rats were randomly divided into 5 groups (n = 14 rats/group) and treated with: (1) ARJ + PBS: (2) ARJ + NG2: tail vein injection of NG2+ HSPs; (3) ARJ + tacrolimus (FK506, oral administration); (4) ARJ + an anti-cMet functional blocking antibody (a-cMet-Ab, I.V) 24 h before the injection of NG2+ HSPs; (5) ARJ + cHGF (clinically used HGF). LEW to LEW syngeneic rats were considered "normal" (n = 14, namely Syn). Significantly prolonged mean survival times (MSTs) and improved graft functions were observed after NG2+ HSP transplantation. An anti-cMet Ab significantly blocked the effect of NG2+ HSPs, suggesting that the effects were likely associated with HGF secreted from NG2+ HSPs. Notably, when intravenously injected into the xenogeneic rat model, the injected cHGF not only prolonged the MST of recipient rats but also increased the number of TUNEL-expressing xenoreactive cytotoxic T lymphocytes (CD8+ T cells). Based on these results, HGF-secreting NG2+ HSPs may specifically target recipient CD8+ T cells by inducing their apoptosis.

The Role of Fibrosis and Liver-Associated Fibroblasts in the Pathogenesis of Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is one of the most aggressive types of cancer and lacks effective therapeutic approaches. Most HCC develops in the setting of chronic liver injury, hepatic inflammation, and fibrosis. Hepatic stellate cells (HSCs) and cancer-associated fibroblasts (CAFs) are key players in liver fibrogenesis and hepatocarcinogenesis, respectively. CAFs, which probably derive from HSCs, activate into extracellular matrix (ECM)-producing myofibroblasts and crosstalk with cancer cells to affect tumor growth and invasion. In this review, we describe the different components which form the HCC premalignant microenvironment (PME) and the tumor microenvironment (TME), focusing on the liver fibrosis process and the biology of CAFs. We will describe the CAF-dependent mechanisms which have been suggested to promote hepatocarcinogenesis, such as the alteration of ECM, CAF-dependent production of cytokines and angiogenic factors, CAF-dependent reduction of immuno-surveillance, and CAF-dependent promotion of epithelial-mesenchymal transition (EMT). New knowledge of the fibrosis process and the role of CAFs in HCC may pave the way for new therapeutic strategies for liver cancer.

The Role of Fibrosis and Liver-Associated Fibroblasts in the Pathogenesis of Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is one of the most aggressive types of cancer and lacks effective therapeutic approaches. Most HCC develops in the setting of chronic liver injury, hepatic inflammation, and fibrosis. Hepatic stellate cells (HSCs) and cancer-associated fibroblasts (CAFs) are key players in liver fibrogenesis and hepatocarcinogenesis, respectively. CAFs, which probably derive from HSCs, activate into extracellular matrix (ECM)-producing myofibroblasts and crosstalk with cancer cells to affect tumor growth and invasion. In this review, we describe the different components which form the HCC premalignant microenvironment (PME) and the tumor microenvironment (TME), focusing on the liver fibrosis process and the biology of CAFs. We will describe the CAF-dependent mechanisms which have been suggested to promote hepatocarcinogenesis, such as the alteration of ECM, CAF-dependent production of cytokines and angiogenic factors, CAF-dependent reduction of immuno-surveillance, and CAF-dependent promotion of epithelial-mesenchymal transition (EMT). New knowledge of the fibrosis process and the role of CAFs in HCC may pave the way for new therapeutic strategies for liver cancer.

Serum albumin levels in relation to tumor parameters in hepatocellular carcinoma patients

BACKGROUND

Serum albumin levels have been shown to have prognostic significance in hepatocellular carcinoma (HCC), as part of an inflammatory index. The aim of this study was to examine the possible relationship of serum albumin levels to parameters of HCC aggressiveness.

METHODS

A large HCC patient cohort was retrospectively examined, and the possible relationships of albumin levels to tumor diameter, multifocality, portal vein thrombosis (PVT) and α-fetoprotein levels were examined.

RESULTS

HCC patients with lower serum albumin levels had significantly larger maximum tumor diameters, greater prevalence of PVT, increased tumor multifocality and higher α-fetoprotein levels, than HCC patients with higher albumin levels. A correlation was found between levels of these tumor parameters and serum albumin levels.

CONCLUSIONS

These results indicate that low serum albumin levels correlate with increased parameter measures of HCC aggressiveness, in addition to their role as a monitor of systemic inflammation. Decreased serum albumin might have a role in HCC aggressiveness.

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

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

Sorafenib and DE605, a novel c-Met inhibitor, synergistically suppress hepatocellular carcinoma

Sorafenib, an oral multikinase inhibitor of Raf, VEGF and PDGF receptor signaling is approved for advanced hepatocellular carcinoma (HCC). One strategy to improve HCC therapy is to combine agents that target key signaling pathways. Aberrant mesenchymal-epithelial transition factor (c-Met) activation is associated with a variety of human malignancies and therefore represents a target for therapy. In this study, we investigated a novel c-Met inhibitor, DE605, together with sorafenib in hepatocellular carcinoma cells in vitro and in vivo. DE605 and sorafenib synergistically induced apoptosis in hepatocellular carcinoma cells. Mechanistically, DE605 activated the FGFR3/Erk pathway, which in turn was inhibited by sorafenib, resulting in synergism. Finally, DE605 and sorafenib significantly inhibited growth of PLC/PRF/5 hepatocellular carcinoma tumor xenografts in athymic nude mice. Importantly, no obvious weight loss (toxicity) was detected. Thus in combination, DE605 and sorafenib target complementary anti-apoptotic pathways and synergistically suppress HCC, providing the rationale for clinical studies with this novel combination.

Impact of MET targeting on tumor-associated angiogenesis and growth of MET mutations-driven models of liver cancer

Deregulated expression of the MET receptor tyrosine kinase has been reported in up to 50% of patients with hepatocellular carcinoma, the most abundant form of liver cancers, and is associated with decreased survival. Consequently, MET is considered as a molecular target in this malignancy, whose progression is highly dependent on extensive angiogenesis. Here we studied the impact of MET small molecule inhibitors on angiogenesis-associated parameters and growth of xenograft liver models consisting of cells expressing MET-mutated variants M1268T and Y1248H, which exhibit constitutive kinase activity. We demonstrate that MET mutations expression is associated with significantly increased production of vascular endothelial growth factor, which is blocked by MET targeting only in cells expressing the M1268T inhibitor-sensitive but not in the Y1248H inhibitor-resistant variant. Decrease in vascular endothelial growth factor production is also associated with reduction of tyrosine phopshorylation of the vascular endothelial growth factor receptor 2 expressed on primary liver sinusoidal endothelial cells and with inhibition of vessel formation. Furthermore, MET inhibition demonstrated an efficient anti-tumor activity and considerable reduction in microvessel density only against the M1268T-derived intrahepatic tumors. Collectively, our data support the role of targeting MET-associated angiogenesis as a major biological determinant for liver tumor growth control.

Emerging molecular targets in oncology: clinical potential of MET/hepatocyte growth-factor inhibitors

The MET/hepatocyte growth-factor (HGF) signaling pathway plays a key role in the processes of embryogenesis, wound healing, and organ regeneration. Aberrant activation of MET/HGF occurs through multiple mechanisms including gene amplification, mutation, protein overexpression, and abnormal gene splicing interrupting autocrine and paracrine regulatory feedback mechanisms. In many cancers including non-small-cell lung cancer, colorectal, gastric, renal, and hepatocellular cancer, dysregulation of MET may lead to a more aggressive cancer phenotype and may be a negative prognostic indicator. Successful therapeutic targeting of the MET/HGF pathway has been achieved using monoclonal antibodies against the MET receptor and its ligand HGF in addition to MET-specific and multitargeted small-molecule tyrosine-kinase inhibitors with several drugs in late-phase clinical trials including onartuzumab, rilotumumab, tivantinib, and cabozantinib. MET frequently interacts with other key oncogenic tyrosine kinases including epidermal growth-factor receptor (EGFR) and HER-3 and these interactions may be responsible for resistance to anti-EGFR therapies. Similarly, resistance to MET inhibition may be mediated through EGFR activation, or alternatively by increasing levels of MET amplification or acquisition of novel "gatekeeper" mutations. In order to optimize development of effective inhibitors of the MET/HGF pathway clinical trials must be enriched for patients with demonstrable MET-pathway dysregulation for which robustly standardized and validated assays are required.

BMP9 is a proliferative and survival factor for human hepatocellular carcinoma cells

TGF-β family members play a relevant role in tumorigenic processes, including hepatocellular carcinoma (HCC), but a specific implication of the Bone Morphogenetic Protein (BMP) subfamily is still unknown. Although originally isolated from fetal liver, little is known about BMP9, a BMP family member, and its role in liver physiology and pathology. Our results show that BMP9 promotes growth in HCC cells, but not in immortalized human hepatocytes. In the liver cancer cell line HepG2, BMP9 triggers Smad1,5,8 phosphorylation and inhibitor of DNA binding 1 (Id1) expression up- regulation. Importantly, by using chemical inhibitors, ligand trap and gene silencing approaches we demonstrate that HepG2 cells autocrinely produce BMP9 that supports their proliferation and anchorage independent growth. Additionally, our data reveal that in HepG2 cells BMP9 triggers cell cycle progression, and strikingly, completely abolishes the increase in the percentage of apoptotic cells induced by long-term incubation in low serum. Collectively, our data unveil a dual role for BMP9, both promoting a proliferative response and exerting a remarkable anti-apoptotic function in HepG2 cells, which result in a robust BMP9 effect on liver cancer cell growth. Finally, we show that BMP9 expression is increased in 40% of human HCC tissues compared with normal human liver as revealed by immunohistochemistry analysis, suggesting that BMP9 signaling may be relevant during hepatocarcinogenesis in vivo. Our findings provide new clues for a better understanding of BMPs contribution, and in particular BMP9, in HCC pathogenesis that may result in the development of effective and targeted therapeutic interventions.

c-Met: A potential therapeutic target for hepatocellular carcinoma

The approval of receptor tyrosine kinase (RTK) targeted agent sorafenib as the first effective drug for the systemic treatment of advanced hepatocellular carcinoma (HCC) represents a milestone in the treatment of this disease. A better understanding of HCC pathogenesis will lead to development of novel targeted treatments. As a typical member of the RTK family, c-Met represents an intriguing target for cancer therapy. The c-Met signaling pathway has been shown to be deregulated and to correlate with poor prognosis in a number of major human cancers. This review discusses the possibility of c-Met as a target in HCC treatment from the following respects: i) c-Met expression and activation profile in HCC, ii) relationship between c-Met and clinicopathologic state and prognosis of HCC, iii) role of c-Met signaling activity in HCC genesis and progression, and iv) strategy of c-Met pathway targeting therapy in HCC treatment.

Management of hepatocellular carcinoma: beyond sorafenib

The positive results of sorafenib have unveiled a new direction of research in the management of hepatocellular carcinoma (HCC). Since then intensive efforts have been focused on development of novel management strategy to further improve the outcome for patients with HCC. Emerging data have suggested that tumor progression of HCC is driven by a number of deregulated signaling pathways and/or epigenetic mechanism. Thus much effort is dedicated to identification of novel agents targeting these dysregulated pathways. Combinations of targeted therapeutics and transarterial chemoembolization (TACE), or different systemic therapeutics also hold the promise to improve treatment outcome beyond sorafenib. This review aims to summarize the current status of clinical development of treatment in HCC. Perspectives on future direction of research will also be discussed.

Management of hepatocellular carcinoma: beyond sorafenib

The positive results of sorafenib have unveiled a new direction of research in the management of hepatocellular carcinoma (HCC). Since then intensive efforts have been focused on development of novel management strategy to further improve the outcome for patients with HCC. Emerging data have suggested that tumor progression of HCC is driven by a number of deregulated signaling pathways and/or epigenetic mechanism. Thus much effort is dedicated to identification of novel agents targeting these dysregulated pathways. Combinations of targeted therapeutics and transarterial chemoembolization (TACE), or different systemic therapeutics also hold the promise to improve treatment outcome beyond sorafenib. This review aims to summarize the current status of clinical development of treatment in HCC. Perspectives on future direction of research will also be discussed.

PPARgamma inhibits hepatocellular carcinoma metastases in vitro and in mice

Background:

We have previously demonstrated that peroxisome proliferator-activated receptor (PPARγ) activation inhibits hepatocarcinogenesis. We aim to investigate the effect of PPARγ on hepatocellular carcinoma (HCC) metastatic potential and explore its underlying mechanisms.

Methods:

Human HCC cells (MHCC97L, BEL-7404) were infected with adenovirus-expressing PPARγ (Ad-PPARγ) or Ad-lacZ and treated with or without PPARγ agonist (rosiglitazone). The effects of PPARγ on cell migration and invasive activity were determined by wound healing assay and Matrigel invasive model in vitro, and in an orthotopic liver tumour metastatic model in mice.

Results:

Pronounced expression of PPARγ was demonstrated in HCC cells (MHCC97L, BEL-7404) treated with Ad-PPARγ, rosiglitazone or Ad-PPARγ plus rosiglitazone, compared with control (Ad-LacZ). Such induction markedly suppressed HCC cell migration. Moreover, the invasiveness of MHCC97L and BEL-7404 cells infected with Ad-PPARγ, or treated with rosiglitazone was significantly diminished up to 60%. Combination of Ad-PPARγ and rosiglitazone showed an additive effect. Activation of PPARγ by rosiglitazone significantly reduced the incidence and severity of lung metastasis in an orthotopic HCC mouse model. Key mechanisms underlying the effect of PPARγ in HCC include upregulation of cell adhesion genes, E-cadherin and SYK (spleen tyrosine kinase), extracellular matrix regulator tissue inhibitors of metalloproteinase (TIMP) 3, tumour suppressor gene retinoblastoma 1, and downregulation of pro-metastatic genes MMP9 (matrix metallopeptidase 9), MMP13, HPSE (heparanase), and Hepatocyte growth factor (HGF). Direct transcriptional regulation of TIMP3, MMP9, MMP13, and HPSE by PPARγ was shown by ChIP-PCR.

Conclusion:

Peroxisome proliferator-activated receptor-gamma exerts an inhibitory effect on the invasive and metastatic potential of HCC in vitro and in vivo, and is thus, a target for the prevention and treatment of HCC metastases.

Targeting c-Met as a promising strategy for the treatment of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a severe condition that is found worldwide. Liver transplantation, surgical resection, and local-regional therapy such as transarterial chemoembolization have made great progress and play a dominant role in HCC management. However, the high frequency of tumor recurrence and/or metastasis after those treatments acquires systematic drug intervention. The approval of sorafenib, an agent that targets receptor tyrosine kinases (RTKs), as the first effective drug for systemic treatment of HCC represents a milestone in treatment of this disease. As a typical member of the RTK family, c-Met represents an intriguing target for cancer therapy. However, the role of the c-Met signal transduction pathway is less unambiguous in HCC pathology, giving rise to concerns about the feasibility of utilizing c-Met targeting approaches for HCC treatment. Recently, studies on des-γ-carboxy prothrombin, an abnormal cytokine secreted by HCC cells, by the current authors and other researchers have highlighted the critical role of c-Met signaling in HCC progression. This review takes a second look at the c-Met signal transduction pathway and discusses the possibility of targeting c-Met as a therapeutic strategy for HCC treatment.

Role of hepatocyte growth factor/c-Met signaling in regulating urokinase plasminogen activator on invasiveness in human hepatocellular carcinoma: a potential therapeutic target

Hepatocyte growth factor (HGF), its transmembrane tyrosine kinase receptor (c-Met), and urokinase type plasminogen activator (uPA) is a key protein in the plasminogen activation system, which plays a proteolytically important role in the invasion and metastasis of various types of cancers. However, the mechanisms by which HGF/c-Met signaling mediates cancer progression and metastasis are unclear. This study was designed to investigate the roles of HGF/c-Met in tumor progression and metastasis in HepG2 and Hep3B hepatoma cell lines. Treatment with HGF increased c-Met phosphorylation in a dose-dependent manner. Activity of c-Met phosphorylation peaked 1-3 min after HGF treatment and then declined. HGF enhanced the protein level and the activity of uPA in HepG2 and Hep3B cells, and the uPAR protein level also increased in a HGF dose-dependent manner. HGF increased cell invasion through the Matrigel. A monoclonal antibody against human uPA receptor, mAb 3936, inhibited HGF-mediated tumor cell invasion in a dose-dependent manner. Down-regulation of uPA using uPA-shRNA induced a decrease in in vitro cell invasion. These results suggest that hepatoma cells express functional c-Met, which may provide a target for a therapeutic basis to interfere with metastases of cancer cells by inhibiting uPA system-mediated proteolysis.

Human cord blood CD34 + cells develop into hepatocytes in the livers of NOD/SCID/γ c null mice through cell fusion

Several studies have shown that hepatocytes can be generated from hematopoietic stem cells, but this event is believed to be rare and to require hepatic damage. To investigate this phenomenon in human cells, we used a NOD/SCID/gamma(c)null (NOG) mouse model that can achieve a tremendously high level of chimerism when transplanted with human hematopoietic cells. Even without hepatotoxic treatment other than irradiation, human albumin and alpha-1-antitrypsin-positive cells were invariably detected in the livers of NOG mice after i.v. transplantation of human cord blood CD34+ cells. Human albumin was detected in the murine sera, indicating functional maturation of the human hepatocytes. Flow cytometric analysis of recipient liver cells in single-cell suspension demonstrated that human albumin-positive cells were also positive for both murine and human MHC and were negative for human CD45. PCR analysis of recipient livers revealed the expression of a wide variety of human hepatocyte- or cholangiocyte-specific mRNAs. These results show that human CD34+ cells fuse with hepatocytes of NOG mice without liver injury, lose their hematopoietic phenotype, and begin hepatocyte-specific gene transcription. These phenomena were not observed when CD34- cells were transplanted. Thus, our model revealed a previously unidentified pathway of human hematopoietic stem/progenitor cell differentiation.

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.

Autocrine production of biologically active hepatocyte growth factor (HGF) by injured human skin

BACKGROUND

Hepatocyte growth factor (HGF) is a potent regenerative factor involved in wound healing. Previous studies have shown that mesenchymal cells produce HGF, stimulating epithelial cells in a paracrine fashion.

OBJECTIVE

To examine whether autocrine HGF production by keratinocytes can occur upon skin injury.

METHODS

A 31-year-old male patient sustained a burn affecting 80% of his total body surface area. Biopsies were taken from intact skin near the injured area, and skin keratinocytes were separated and cultured. Conditioned medium from keratinocytes was analyzed for HGF by ELISA, surface plasmon resonance (SPR), and dot blotting. Binding of HGF from conditioned medium to its receptor, c-Met, was compared with recombinant HGF by SPR. Finally, we examined the motogenic effect on mouse transformed skin epithelial cells (CCL-53.1) of HGF from conditioned medium.

RESULTS

HGF was detected in the cultured keratinocyte medium. Similar to recombinant HGF, HGF from conditioned medium had a high affinity for dextran sulfate and albumin, and the same epitopes were engaged by the interaction of HGF with the c-Met receptor. The conditioned medium from keratinocytes obtained from the burn patient, but not medium from keratinocytes obtained from healthy volunteers, accelerated the motogenesis of CCL-53.1 cells. Unexpectedly, anti-HGF antibodies did not prevent this effect. However, anti-c-Met antibodies completely inhibited the motogenic effect.

CONCLUSION

Upon injury, human skin keratinocytes might produce biologically active HGF in an autocrine fashion. This HGF might have different structural and/or biological properties from HGF produced by mesenchymal cells.

Inhibition of angiogenesis and HGF-cMET-elicited malignant processes in human hepatocellular carcinoma cells using adenoviral vector-mediated NK4 gene therapy

NK4 is an hepatocyte growth factor (HGF)-antagonist and a broad angiogenesis inhibitor. NK4 gene therapy has confirmed antitumor efficacy on cancers with intact HGF-cMET signaling pathway. However, the feasibility to treat tumors in which the effect of the HGF-cMET signaling pathway is less unambiguous or may even be inhibitory on carcinogenesis, such as hepatocellular carcinoma (HCC) with NK4 needs further assessment. Therefore, we evaluated the effects of adenoviral vector-mediated expression of NK4 on the biological behavior of a series of HCC cell lines in vitro and on HepG2 xenografts in vivo. In vitro, transduction of HCC cell lines with the replication-deficient recombinant adenoviral vector AdCMV.NK4 resulted in significant inhibition of proliferation over and above the antimitogenic effects of HGF. In addition, HGF-induced scattering and invasion through matrigel were inhibited effectively. Moreover, transduced HCC cells produced sufficient amounts of NK4 protein to achieve bystander effects involving reduced migration of nontransduced tumor cells and reduced proliferation of endothelial cells. Finally, treatment of established HepG2 xenografts with AdCMV.NK4 resulted in significant tumor growth delay and significant reduction of intratumoral microvessel density. In conclusion, NK4 gene therapy is a promising strategy to treat HCC based on the pleiotropic functions of NK4 interfering with tumor growth, invasion, metastasis and angiogenesis.

Molecular control of liver development

Recent studies using animal models have elucidated a growing number of evolutionarily conserved genes and pathways that control liver development from the embryonic endoderm. It is increasingly clear that the genetic programs active in embryogenesis are often deregulated or reactivated in disease, cancer, and tissue repair. Understanding the molecular control of liver development should impact diagnosis and treatment of pediatric and adult liver diseases and aid in efforts to differentiate liver tissue in vitro for stem cell-based therapies.

Proteinase and growth factor alterations revealed by gene microarray analysis of human diabetic corneas

PURPOSE

To identify proteinases and growth factors abnormally expressed in human corneas of donors with diabetic retinopathy (DR), additional to previously described matrix metalloproteinase (MMP)-10 and -3 and insulin-like growth factor (IGF)-I.

METHODS

RNA was isolated from 35 normal, diabetic, and DR autopsy human corneas ex vivo or after organ culture. Amplified cRNA was analyzed using 22,000-gene microarrays (Agilent Technologies, Palo Alto, CA). Gene expression in each diabetic corneal cRNA was assessed against pooled cRNA from 7 to 9 normal corneas. Select differentially expressed genes were validated by quantitative real-time RT-PCR (QPCR) and immunohistochemistry. Organ cultures were treated with a cathepsin inhibitor, cystatin C, or MMP-10.

RESULTS

More than 100 genes were upregulated and 2200 were downregulated in DR corneas. Expression of cathepsin F and hepatocyte growth factor (HGF) genes was increased in ex vivo and organ-cultured DR corneas compared with normal corneas. HGF receptor c-met, fibroblast growth factor (FGF)-3, its receptor FGFR3, tissue inhibitor of metalloproteinase (TIMP)-4, laminin alpha4 chain, and thymosin beta(4) genes were downregulated. The data were corroborated by QPCR and immunohistochemistry analyses; main changes of these components occurred in corneal epithelium. In organ-cultured DR corneas, cystatin C increased laminin-10 and integrin alpha(3)beta(1), whereas in normal corneas MMP-10 decreased laminin-10 and integrin alpha(3)beta(1) expression.

CONCLUSIONS

Elevated cathepsin F and the ability of its inhibitor to produce a more normal phenotype in diabetic corneas suggest increased proteolysis in these corneas. Proteinase changes may result from abnormalities of growth factors, such as HGF and FGF-3, in DR corneas. Specific modulation of proteinases and growth factors could reduce diabetic corneal epitheliopathy.

Expression of augmenter of liver regeneration (ALR) in human liver cirrhosis and carcinoma

AIMS

To determine the expression of a protein termed augmenter of liver regeneration (ALR), recently found to have a specific and beneficial effect on the process of liver regeneration in normal and diseased human liver.

METHODS AND RESULTS

ALR expression in normal and cirrhotic human livers with various underlying diseases as well as in tissue samples of hepatocellular carcinoma (HCC) and cholangiocellular carcinoma (CCC) was analysed by immunohistochemistry and quantitative reverse transciptase-polymerase chain reaction (RT-PCR). Expression analysis of ALR in total liver protein extracts by Western blotting showed mainly dimeric ALR protein. Immunohistochemically, cytosolic and perinuclear immunosignals were found in hepatocytes and cholangiocytes in normal, cirrhotic or cancerous liver tissue and only weak signals in some endothelial cells in normal livers. Quantitative mRNA analysis revealed significantly increased ALR expression in cirrhosis compared with normal liver tissue. In HCC and CCC ALR mRNA expression was also significantly enhanced compared with normal liver tissue, but expression levels did not differ from the matching non-neoplastic tissue in the same patient.

CONCLUSIONS

The findings suggest an important role for ALR in hepatocellular regeneration in liver cirrhosis as well as in hepatocarcinogenesis and therefore its potential value in the clinical diagnosis of hepatic cirrhosis and cancer.

beta-Catenin and met deregulation in childhood Hepatoblastomas

Activation of the Wnt/beta-catenin and hepatocyte growth factor/Met signaling has been implicated in various tumors. Owing to the cross-talk between these pathways and aberrant redistribution of beta-catenin in hepatoblastomas, we examined their status in this tumor. This study examined changes in beta-catenin and Met in paired pretreatment and post-treatment hepatoblastoma tissues in relation to their effects on proliferation and target genes such as c-myc and cyclin-D1. In this study we compared proliferation indices, beta-catenin staining and its known molecular targets, c-myc and cyclin-D1, and Met, a tyrosine kinase receptor for hepatocyte growth factor in pretreatment and post-treatment specimens. Pretreatment and post-treatment sections from 13 children, ages 11 weeks to 9 years, were analyzed for these markers by immunohistochemistry. All tumors (13 of 13) displayed increased proliferation and beta-catenin (cytoplasmic and nuclear) staining in pretreatment biopsies that remained relatively unaffected after treatment. Aberrant Met staining (cytoplasmic) was observed in all pretreatment samples that decreased considerably after treatment in 11 of 13 patients. A significant subset of these tumors showed increased c-myc and cyclin-D1 staining in pretreatment biopsies that decreased after chemotherapy in most cases. beta-Catenin redistribution in tumor cells corresponds to proliferation in hepatoblastomas. However, beta-catenin nuclear localization remains unaffected in viable hepatoblastoma tissue after chemotherapy. In contrast, Met undergoes a prominent decrease after treatment and thus might be important in pathogenesis of hepatoblastoma.

Diagnostic validity of hepatocyte growth factor as marker for rejection in the follow-up of patients after heart transplantation

BACKGROUND

Hepatocyte growth factor (HGF) is a member of growth factor with a variety of known activities, including angiogenesis promotion and antiapoptotic action. It prevents acute graft-versus-host disease after bone marrow transplantation and prolongs allogenic graft survival in rats. The aim of the study was to investigate the relationship between serum HGF concentration and the grade of acute cellular rejection of heart transplant.

METHODS

We studied 68 male heart recipients. All of them received triple-drug immunosuppression: cyclosporine A, prednisone, and azathioprine or mycofenolate mofetil. All patients were without signs of heart failure. Blood samples were taken before elective ambulatory endomyocardial biopsy. Biopsy specimens were graded with the International Society for Heart and Lung Transplantation scale. Acute cellular rejection grade 3A and higher were considered as significant. Measurement of serum HGF was made by enzyme-linked immunosorbent assay.

RESULTS

We found a positive relationship between serum HGF levels and grade of cellular rejection. As an indicator for the detection of cell rejection processes, HGF with cutoff 2000 pg/ml seems to be useful.

CONCLUSIONS

The results of this study demonstrate that HGF can be useful as an indicator for heart graft cell rejection.

Des-gamma-carboxy prothrombin is a potential autologous growth factor for hepatocellular carcinoma

Des-gamma-carboxyl prothrombin (DCP) is a well recognized tumor marker for hepatocellular carcinoma (HCC). In the present study, we demonstrate that DCP has a mitogenic effect on HCC cell lines. Purified DCP stimulated DNA synthesis of Hep3B and SK-Hep-1 cells in a dose-dependent manner. DCP was found to bind with cell surface receptor Met causing Met autophosphorylation and also to activate STAT3 signaling pathway through Janus kinase 1. Luciferase gene reporter analysis showed that DCP induced STAT3-related transcription. Small interfering RNAs against both STAT3 and Met abrogated DCP-induced cell proliferation. DCP did not affect the mitogen-activated protein kinase pathway, Myc signaling pathway, or phosphoinositide 3-kinase/Akt pathway. Based on these results, we believe that DCP acts as an autologous mitogen for HCC cell lines. The Met-Janus kinase 1-STAT3 signaling pathway may be a major signaling pathway for DCP-induced cell proliferation.

c-Met as a target for human cancer and characterization of inhibitors for therapeutic intervention

Receptor tyrosine kinase (RTK) targeted agents such as trastuzumab, imatinib, bevacizumab, and gefitinib inhibitors have illustrated the utility of targeting this protein class for treatment of selected cancers. A unique member of the RTK family, c-Met, also represents an intriguing target for cancer therapy that is yet to be explored in a clinical setting. The proto-oncogene, c-Met, encodes the high-affinity receptor for hepatocyte growth factor (HGF) or scatter factor (SF). c-Met and HGF are each required for normal mammalian development and have been shown to be particularly important in cell migration, morphogenic differentiation, and organization of three-dimensional tubular structures (e.g. renal tubular cells, gland formation, etc.) as well as cell growth and angiogenesis. Both c-Met and HGF have been shown to be deregulated in and to correlate with poor prognosis in a number of major human cancers. New data describing the constitutive phosphorylation of c-Met in a number of human tumors is presented here along with a variety of mechanisms by which c-Met can become activated, including mutation and gene amplification. In support of the clinical data implicating c-Met activation in the pathogenesis of human cancers, introduction of c-Met and HGF (or mutant c-Met) into cells conferred the properties of motility, invasiveness, and tumorgenicity to the transformed cells. Conversely, the inhibition of c-Met with a variety of receptor antagonists inhibited the motility, invasiveness, and tumorgenicity of human tumor cell lines. Consistent with this observation, small-molecule inhibitors of c-Met were developed that antagonized c-Met/HGF-dependent phenotypes and tumor growth in mouse models. This review will address the potential for development of c-Met inhibitors for treatment of human cancers with particular emphasis on recent findings with small-molecule inhibitors.

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.

Hepatocyte growth factor and c-Met expression in rat and human liver fibrosis

BACKGROUND

Hepatocyte growth factor (HGF) is a potent mitogen for hepatocytes in vitro.

AIMS

Substitution of HGF was suggested for human liver disease on the basis of animal experiments. The cellular sources of HGF and its receptor, c-Met, in liver disease in vivo are not well defined.

METHODS

We characterised HGF and c-Met expression in normal and cirrhotic human livers and rat livers at various time points after CCl4 administration by in situ hybridisation and immunohistology. HGF transcripts were restricted to resting and activated stellate cells in rat and human liver.

RESULTS

In rat liver, HGF showed peak levels 6-12 h following acute intoxication, and remained increased after repeated CCl4 injury. HGF transcript levels were very low in normal human liver, but excessively raised in fibrosis/cirrhosis. In contrast, HGF immunoreactivity was found not only in perisinusoidal/periductular cells but also in cholangiocytes of proliferating ductules. c-Met RNA and protein was expressed in hepatocytes, cholangiocytes, and arteriolar endothelial cells.

CONCLUSIONS

The HGF-specific immunostaining of proliferating cholangioles in the absence of HGF RNA suggests c-Met-mediated uptake of HGF and paracrine stimulation of cholangiocellular proliferation. Mitogenic effects of HGF on hepatocytes may therefore be accompanied by undesired cholangiogenesis and angiogenesis limiting its therapeutic value in chronic liver disease.

Disease- and cell-specific expression of GP73 in human liver disease

OBJECTIVES

GP73, a Golgi membrane protein, is expressed at high levels in hepatocytes of patients with decompensated cirrhosis. Its expression in other forms of liver disease has not been investigated. Therefore, we studied GP73 expression in patients with noncirrhotic liver disease.

METHODS

GP73 expression was detected immunohistochemically and by immunofluorescence microscopy in patients with acute hepatitis of various etiologies, autoimmune hepatitis, chronic HCV infection, and alcoholic liver disease. In order to quantitate hepatocyte GP73 expression, an immunohistochemical scoring system was developed, and validated by a direct comparison with GP73 protein levels as determined by Western blotting.

RESULTS

GP73 immunostaining and Western blotting data were highly correlated, demonstrating the suitability of the immunohistochemical scoring system to quantitate hepatocyte GP73 expression. Hepatocyte GP73 expression was increased in patients with acute and autoimmune hepatitis. Treatment of autoimmune hepatitis was associated with a normalization of GP73 expression, indicating that the initial upregulation was reversible. Increased levels of GP73 expression were also noted in chronic HCV infection and alcoholic liver disease. Under these conditions, GP73 levels were correlated with disease stage but not grade. GP73 immunoreactivity was occasionally detected in alpha-SMA-positive, sinusoidal lining cells, suggesting activated stellate cells as a potential source of GP73.

CONCLUSIONS

Hepatocyte GP73 levels are upregulated in acute hepatitis and during the progression of liver disease to cirrhosis. This expression pattern suggests the presence of two regulatory mechanisms, the first triggered during acute hepatocellular injury, the second during the progression of chronic liver disease.

Expression of ephrin-B1 in hepatocellular carcinoma: possible involvement in neovascularization

BACKGROUND/AIMS

Hepatocellular carcinoma (HCC) is, in general, a hypervascular tumor. Ephrin/Eph molecules have recently been reported as possible regulators of angiogenesis. We aimed to clarify the role of ephrin-Bs (B1-B3) in the progression of HCC.

METHODS

Ephrin-Bs transcripts in 26 HCC and their corresponding non-tumor liver tissues were analyzed by the quantitative reverse transcription-polymerase chain reaction. We established ephirn-B1 overexpressing cell in a human HCC cell line, PLC/PRF/5 cell, and their in vivo growth monitored after subcutaneous injection into nude mice. Neovascularization in the inoculated tumors was evaluated by the immunohistochemical staining of CD31. The migration and proliferation of human umbilical vein endothelial cells (HUVECs) in response to soluble ephrin-B1-Fc was examined.

RESULTS

The expression of the ephrin-B1 transcript but not -B2 and -B3 transcripts was significantly higher in HCC tissues than in non-tumor tissues (P<0.05). The ephrin-B1 overexpressing cells developed tumors more rapidly than controls in vivo (P<0.05), although in vitro cell growth was not affected. The tumor vessel number significantly increased in the ephrin-B1 overexpressing tumors (P<0.0001). In addition, in vitro studies revealed that ephrin-B1 induced migration and proliferation of HUVECs.

CONCLUSIONS

Ephrin-B1 may be involved in in vivo tumor progression by promoting neovascularization in HCC.

Hepatocyte growth factor and its receptor are required for malaria infection

Plasmodium, the causative agent of malaria, must first infect hepatocytes to initiate a mammalian infection. Sporozoites migrate through several hepatocytes, by breaching their plasma membranes, before infection is finally established in one of them. Here we show that wounding of hepatocytes by sporozoite migration induces the secretion of hepatocyte growth factor (HGF), which renders hepatocytes susceptible to infection. Infection depends on activation of the HGF receptor, MET, by secreted HGF. The malaria parasite exploits MET not as a primary binding site, but as a mediator of signals that make the host cell susceptible to infection. HGF/MET signaling induces rearrangements of the host-cell actin cytoskeleton that are required for the early development of the parasites within hepatocytes. Our findings identify HGF and MET as potential targets for new approaches to malaria prevention.

Liver-specific gene expression in cultured human hematopoietic stem cells

Hematopoietic and hepatic stem cells share characteristic markers such as CD34, c-kit, and Thy1. Based on the recent observations that hepatocytes may originate from bone marrow, we investigated the potential of CD34(+) bone marrow cells to differentiate into hepatocytic cells in vitro. CD34(+) and CD34(-) human bone marrow cells were separated by magnetic cell sorting. Cells were cultured on a collagen matrix in a defined medium containing hepatocyte growth factor. Cell count and size were measured by flow cytometry, and reverse transcription polymerase chain reaction was carried out for the liver-specific markers CK-19 and albumin. During cell culture, CD34(+) cells showed an increasing cell number and proliferative activity as assessed by Ki-67 staining. Under the specified culture conditions, CD34(+) cells expressed albumin RNA and CK-19 RNA after 28 days, whereas CD34(-) cells did not show liver-specific gene expression. The results indicate that CD34(+) adult human bone marrow stem cells can differentiate into hepatocytic cells in vitro.

Albumin-expressing hepatocyte-like cells develop in the livers of immune-deficient mice that received transplants of highly purified human hematopoietic stem cells

Rodent bone marrow cells can contribute to liver. If these findings are applicable to humans, marrow stem cells could theoretically be harvested from a patient and used to repair his/her damaged liver. To explore this potential, CD34(+) or highly purified CD34(+)CD38(-)CD7(-) human hematopoietic stem cells from umbilical cord blood and bone marrow were transplanted into immunodeficient mice. One month after transplantation, carbon tetrachloride (CCl(4)) was administered into the mice to induce liver damage and hepatocyte proliferation. Mice were analyzed in comparison with CCl(4)-injured mice that did not receive transplants and noninjured controls that received transplants with the same stem cell populations, one month after liver damage. Human-specific albumin mRNA and protein were expressed in the mouse liver and human albumin was detected in the serum of mice that had received CCl(4) injury. Human alpha-fetoprotein was never expressed, but in some mice, human cytokeratin 19 was expressed, which may indicate bile duct development in addition to the albumin-secreting hepatocyte-like cells. Human albumin was not expressed in the starting stem cell populations in injured mice that did not receive transplants nor in noninjured mice that had received transplants of human stem cells. Human albumin expression was detected only in CCl(4)-treated mice that received transplants of human stem cells, and recovery was increased by administration of human hepatocyte growth factor 48 hours after the CCl(4)-mediated liver injury. Our studies provide evidence that human "hematopoietic" stem/progenitor cell populations have the capacity to respond to the injured liver microenvironment by inducing albumin expression.

High serum hepatocyte growth factor level in patients with non-Hodgkin's lymphoma

Higher pretreatment serum hepatocyte growth factor (HGF) levels were observed in patients with multiple myeloma and Hodgkin's disease, but not in those with non-Hodgkin's lymphoma (NHL). We examined patients' serum levels at diagnosis using enzyme-linked immunosorbent assay and histological expression of HGF in pathological specimens of lymphoma, in relation to clinical features. The subjects were 77 NHL patients and 40 healthy controls. The serum levels of HGF in NHL patients at diagnosis were significantly higher than those in healthy controls (median 1019 vs. 689 pg/mL, P < 0.001). At diagnosis, patients with more than two sites of extranodal involvement (P = 0.001), higher scores of international prognostic index (P = 0.015), and advanced Ann Arbor stage (P = 0.023) had a higher level of serum HGF. Although the association of pretreatment serum HGF level and survival was not significant, a correlation of serial change of serum HGF levels with treatment response was found in limited cases. Furthermore, HGF expression of lymphoma tissues was shown in 18 of 24 (75%) different NHL subtypes, including most of the diffuse large B cell lymphoma (12 of 15, 80%). In conclusion, our study showed higher pretreatment serum HGF levels in NHL patients, which was related to clinical features; and the serial change of HGF seemed to parallel the treatment response. The pathogenic role of HGF in NHL patients was further highlighted by a modest expression of HGF in most of the diffuse large B cell lymphoma.

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.

Scatter factor/hepatocyte growth factor stimulation of glioblastoma cell cycle progression through G(1) is c-Myc dependent and independent of p27 suppression, Cdk2 activation, or E2F1-dependent transcription

Scatter factor/hepatocyte growth factor (SF/HGF) expression has been linked to malignant progression in glial neoplasms. Using two glioma cell lines, U373MG and SNB-19, we have demonstrated that SF/HGF stimulation allows cells to escape G(1)/G(0) arrest induced by contact inhibition or serum withdrawal. SF/HGF induced effects on two mechanisms of cell cycle regulation: suppression of the cyclin-dependent kinase inhibitor p27 and induction of the transcription factor c-Myc. Regulation of p27 by SF/HGF was posttranslational and is associated with p27 nuclear export. Transient transfections of U373MG and SNB-19 with wild-type p27 and a degradation-resistant p27T187A mutant were insufficient to induce cell cycle arrest, and SF/HGF downregulation of p27 was not necessary for cell cycle reentry. Analysis of Cdk2 kinase activity and p27 binding to cyclin E complexes in the presence of exogenous wild-type p27 or p27T187A demonstrated that Cdk2 activity was not necessary for SF/HGF-mediated G(1)/S transition. Similarly, overexpression of dominant-negative forms of Cdk2 did not block SF/HGF-triggered cell cycle progression. In contrast, SF/HGF transcriptionally upregulated c-Myc, and overexpression of c-Myc was able to prevent G(1)/G(0) arrest in the absence of SF/HGF. Transient overexpression of MadMyc, a dominant-negative chimera for c-Myc, caused G(1)/G(0) arrest in logarithmically growing cells and blocked SF/HGF-mediated G(1)/S transition. c-Myc did not exert its effects through p27 downregulation in these cell lines. SF/HGF induced E2F1-dependent transcription, the inhibition of which did not block SF/HGF-induced cell cycle progression. We conclude that SF/HGF prevents G(1)/G(0) arrest in glioma cell lines by a c-myc-dependent mechanism that is independent of p27, Cdk2, or E2F1.

Isolation of a genomic clone containing the promoter region of the human ATP binding cassette (ABC) transporter, ABCB6

We previously reported on the isolation of a new rat ATP binding cassette (ABC) transporter, ABCB6. We now report the isolation of the full-length cDNA and genomic clones containing the human ABCB6 gene. ABCB6 is 100% identical to the cloned MTABC3 human ABC transporter and contains the typical ABC signature, Walker A and B motifs. We found that HuABCB6 is expressed at low levels in normal human liver. We found that ABCB6 was overexpressed in human hepatocellular carcinomas compared to paired surrounding non-malignant tissue. We found that there was no difference in ABCB6 gene copy between human liver cancer and its paired non-malignant tissue. Because HuABCB6 was overexpressed in human cancers compared to peri-tumoral tissue in the absence of gene amplification, transcriptional regulation may play an important role in its expression. Therefore, we isolated a 14 kb genomic DNA clone containing the HuABCB6 promoter and 5'-flanking region. The 5'-flanking region contains a CpG island, lacks an appropriately positioned TATA element and contains a number of putative transcription factor binding sites. Two transcription start sites were identified by S1 nuclease mapping at -274 and -296 bp from the start codon. Transient transfection of the HuABCB6 promoter constructs (HuABCB6/1.68, 1.39, 1.13, 0.90, 0.52) containing the luciferase reporter gene resulted in a 1100-2300-fold increase in luciferase activity compared to the empty vector control whereas HuABCB6/1.68 subcloned in the reverse orientation resulted in no activity. We observed a significant decrease in luciferase activity with the promoter constructs, HuABCB6/0.25, 0.15 and 0.06, which indicates that an orientation-dependent functional promoter is contained within our previously predicted promoter region of -315 bp to -565 bp as deletion of this 250 bp sequence resulted in a loss of promoter activity.

Bacterial lipopolysaccharide induces transforming growth factor beta and hepatocyte growth factor through toll-like receptor 2 in cultured human colon cancer cells

This study examined, in human cancer lines, the pattern of cytokine production stimulated by lipopolysaccharide (LPS), a major component of outer surface of gram-negative bacteria, and characterized the expression pattern of CD14, cell surface LPS receptor antigen, and toll-like receptors (TLRs), which appear to be key regulators of the innate immune response system. Two colon cancer cell lines (DLD and LoVo), a hepatocellular carcinoma cell line and a myelomonocytic cell line were incubated with LPS for 0-72 h, and transforming growth factor (TGF) beta1 and beta2, hepatocyte growth factor (HGF) and interleukins 6, 8 and 15 were assayed. The only changes induced by incubation with LPS were significant increases in TGFbeta1 production at 12 h, and in HGF production at 72 h, in LPS-stimulated DLD cells, and significant increases in TGFbeta2 production after 12 h and in HGF after 72 h in LoVo cells. Using reverse transcriptase-polymerase chain reaction analysis, expression of CD14 and TLR-2 mRNA was detected in DLD and LoVo cells, and expression of TLR-4 mRNA was detected in PLC/PRF/5 and KG-1 cells. These results suggest that LPS induces TGFbeta and HGF production mediated by CD14/TLR-2 in cultured human colon cancer cell lines.

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.

Expression of epidermal growth factor and its receptor in cirrhotic liver disease

Polypeptide growth factors, including epidermal growth factor (EGF), play a central role in regulating hepatocyte growth both in vivo and in primary culture. To characterize EGF gene expression in the pathogenesis of regenerative cirrhotic fibrosis, we employed biotinylated antisense oligonucleotide probes to localize hepatic mRNA transcripts in situ. In control tissue and regenerative hepatic nodules, EGF receptor (EGFR) mRNA transcripts were expressed constitutively. In contrast, oligonucleotide probes targeting the human EGF coding region showed that EGF transcription was extremely low in control liver but was highly elevated and localized to regenerative hepatic nodules and bile duct epithelia of cirrhotic liver. To determine whether EGF mRNA accumulation accompanied a comparable increase in the EGF peptide, we performed immunohistochemistry using an antibody specific for the nonprocessed peptide aminoterminus. We observed that positive localized EGF staining paralleled its mRNA transcript. These results indicate that EGF upregulation is a characteristic of cirrhotic liver disease and suggest that persistent de novo ligand synthesis and its signaling contribute to an autocrine-mediated hepatocyte proliferation within the regenerative nodule.

Nonrandom chromosomal aberrations and cytogenetic heterogeneity in gallbladder carcinomas

Chromosome banding analysis of 11 short-term cultured gallbladder carcinomas revealed acquired clonal aberrations in seven tumors (five primary and two metastases). Three of these had one clone, whereas the remaining four were cytogenetically heterogeneous, displaying two to seven aberrant clones. Of a total of 21 abnormal clones, 18 had highly complex karyotypes and three exhibited simple numerical deviations. Double minutes and homogeneously staining regions were observed in one and two carcinomas, respectively. To characterize the karyotypic profile of gallbladder cancer more precisely, we have combined the present findings with our three previously reported cases, thereby providing the largest cytogenetic database on this tumor type to date. A total of 287 chromosomal breakpoints were identified, 251 of which were found in the present study. Chromosome 7 was rearranged most frequently, followed by chromosomes 1, 3, 11, 6, 5, and 8. The bands preferentially involved were 1p32, 1p36, 1q32, 3p21, 6p21, 7p13, 7q11, 7q32, 19p13, 19q13, and 22q13. Nine recurrent abnormalities could, for the first time, be identified in gallbladder carcinoma: del(3)(p13), i(5)(p10), del(6)(q13), del(9)(p13), del(16)(q22), del(17)(p11), i(17)(q10), del(19)(p13), and i(21)(q10). The most common partial or whole-arm gains involved 3q, 5p, 7p, 7q, 8q, 11q, 13q, and 17q, and the most frequent partial or whole-arm losses affected 3p, 4q, 5q, 9p, 10p, 10q, 11p, 14p, 14q, 15p, 17p, 19p, 21p, 21q, and Xp. These chromosomal aberrations and imbalances provide some starting points for molecular analyses of genomic regions that may harbor genes of pathogenetic importance in gallbladder carcinogenesis. Genes Chromosomes Cancer 26:312-321, 1999.

A src-related kinase in the brush border membranes of gastrointestinal cells is regulated by c-met

Hepatocyte growth factor (HGF) elicits pleiotropic cellular responses by binding to c-met, a PTK transmembrane receptor. The recent identification of HGF in fluids which enter the gut lumen suggests a mechanism by which c-met molecules are accessible to ligand that is present near the apical surfaces of polarized enterocytes. A subset of c-met molecules was detected, by confocal and immunoelectron microscopic analysis, which colocalizes with a recently identified src-related gastrointestinal tyrosine kinase (gtk) in the brush border membranes of enterocytes. Furthermore, treatment of c-met/gtk-transfected cells with a chemical cross-linking agent revealed that c-met forms a physical complex with gtk, in vivo. Not surprisingly, activation of the receptor molecules with HGF rapidly stimulated gtk enzymatic activity. Similarly, the stimulation of gtk activity occurred when nontransfected primary hepatocytes were exposed to ligand. These findings suggest a model in which HGF binding to luminally accessible c-met stimulates gtk activity. This brush border-associated c-met-linked pathway may be associated with a defined set of epithelial cell responses.