Hepatoblastoma Tissues Research Articles

Ginsenoside Rg1 impairs homologous recombination repair by targeting CtBP-interacting protein and sensitizes hepatoblastoma cells to DNA damage.

The ginsenoside Rg1, the primary pharmacologically active ingredient of the traditional Chinese herb ginseng, is widely used in the clinical treatment of diseases of the immune and nervous systems. Recent studies have shown that it also has an antitumor effect. In this study, we explored the effects of Rg1 on hepatoblastoma (HB) and its underlying mechanisms. We demonstrated that Rg1 significantly inhibited HB cell growth both in vivo and in vitro. Mechanistic studies revealed that Rg1 impaired homologous recombination and triggered double-strand breaks in HB cells by directly targeting CtBP-interacting protein (CtIP), a key double-strand break repair factor, which is highly expressed in HB tissues. Moreover, we also demonstrated that Rg1 sensitized HB cells to DNA-damaging agents both in vitro and in vivo. In conclusion, our data not only demonstrate the potential clinical application of Rg1 as a novel chemotherapeutic candidate but also offer a mechanism-based therapeutic option by which DNA-damaging agents can be used in combination with Rg1 to target HB.

Kockdown of OIP5-AS1 expression inhibits proliferation, metastasis and EMT progress in hepatoblastoma cells through up-regulating miR-186a-5p and down-regulating ZEB1

Long non-coding RNA OIP5-AS1 has been studied in human diseases, including several kinds of cancers. It was not studied or reported in hepatoblastoma, so we chose it to do our research in hepatoblastoma. We thought OIP5-AS1 was oncogenic in hepatoblastoma for the high expression of it in hepatoblastoma tissues and cells. OIP5-AS1 knockdown was carried out in cancer cells. Unsurprisingly, this action was verified to be able to inhibit cell proliferation, metastasis and EMT progress in hepatoblastoma. We then measured the low expression level of miR-186a-5p and the high expression level of ZEB1 in hepatoblastoma tissues and cells. The relevance among them was analyzed by using correlation analysis. In order to prove the ceRNA pattern in this study, nuclear separation experiment, RIP assay and dual luciferase assays were all put into use. We discovered OIP5-AS1 is located in nucleus of cancerous cells. It could target to miR-186a-5p and up-regulate the target gene of miR-186a-5p (ZEB1). Finally, rescue assay was utilized and proved the effect of OIP5-AS1-miR-186a-5p-ZEB1 axis on hepatoblastoma cell activities. Based on all above findings, we came into a conclusion that OIP5-AS1 is a ceRNA in Hepatoblastoma cells through modulating miR-186a-5p/ZEB1.

Nuclear paraspeckle assembly transcript 1 promotes the metastasis and epithelial-mesenchymal transition of hepatoblastoma cells by inhibiting miR-129-5p.

The abnormal expression of nuclear paraspeckle assembly transcript 1 (NEAT1) may serve critical functions for the development and progression of various types of human tumor. However, the expression and biological function of NEAT1 in hepatoblastoma (HB) and the underlying mechanisms for the function of NEAT1 in HB remain largely uncharacterized. In the present study, the results of reverse transcription-quantitative polymerase chain reaction revealed that the expression of NEAT1 was significantly elevated in HB tissues. HB tissues with metastasis also exhibited significantly increased levels of NEAT1 compared with tissues without metastasis. The biological functions of NEAT1 were then assessed using gain-/loss-of-function studies. The results of in vitro assays revealed that inhibiting NEAT1 expression reduced the migration and invasion of HepG2 cells. By contrast, the induced expression of NEAT1 exhibited the opposite effect. The present study also demonstrated that the inhibition of NEAT1 expression prevented the epithelial-mesenchymal transition of HepG2 cells, whereas forced expression of NEAT1 exhibited the opposite effect. In addition, it was confirmed that NEAT1 could modulate the expression of microRNA (miR)-129-5p in HepG2 cells, and that NEAT1 may exert its effect on the metastatic behaviors and epithelial-mesenchymal transition of HepG2 cells by inhibiting miR-129-5p. In conclusion, the present study indicated that NEAT1 expression was aberrantly increased in HB and that it may promote the metastasis of HB cells by inhibiting miR-129-5p. Targeting NEAT1 may potentially be a novel therapeutic option for treating patients with HB.

Central role of mTORC1 downstream of YAP/TAZ in hepatoblastoma development

Hepatoblastoma (HB) is the most common type of liver malignancy in children. Recent studies suggest that activation of Yes-associated protein (YAP) is a major molecular event in HB development, as activated YAP synergizes with mutant β-catenin to promote HB formation in mice (YAP/β-catenin). However, how YAP regulates HB development remains poorly defined. Similarly, de-regulation of mammalian target of rapamycin complex 1 (mTORC1) signaling has been implicated in multiple tumor types, but its functional role in HB development is scarcely understood. In the present study, we found that mTORC1 is activated in human HB cells and YAP/β-catenin-induced mouse HB tumor tissues. mTOR inhibitor MLN0128 significantly inhibits human HB cell growth in vitro. Furthermore, ablation of Raptor, the unique subunit of mTORC1, strongly delayed YAP/β-catenin-induced HB development in mice. At the molecular level, we found that expression of the amino acid transporter SLC38A1 is induced in mouse HB tissues, and amino acid deprivation leads to mTORC1 suppression in HB cell lines. Silencing of YAP and/or its paralog, transcriptional co-activator with PDZ binding motif (TAZ), decreased SLC38A1 expression as well as mTORC1 activation in HB cells. Furthermore, a frequent and concomitant upregulation of mTORC1 and SLC38A1 was detected in a collection of human HB specimens. Altogether, our study demonstrates the key role of mTORC1 in HB development. YAP and TAZ promote HB development via inducing SLC38A1 expression, whose upregulation leads to mTORC1 activation. Targeting mTOR pathway or amino acid transporters may represent novel therapeutic strategies for the treatment of human HB.

Aberrant KLK4 gene promoter hypomethylation in pediatric hepatoblastomas

DNA methylation has a crucial role in cancer biology and has been recognized as an activator of oncogenes and inactivator of tumor suppressor genes, both of which are mechanisms for tumorigenesis. Kallikrein-related peptidase 4 (KLK4), has been suggested to be an oncogene in various types of cancer. The aim of the present study was to assess the DNA methylation patterns of the KLK4 gene in cancerous samples harvested from patients with hepatoblastoma (HB). KLK4 mRNA expression levels were detected using reverse transcription-quantitative polymerase chain reaction and assessed its DNA methylation patterns using high-throughput mass spectrometry on a matrix-assisted laser desorption/ionization time-of-flight mass array. A total of 10 HB and 10 normal liver tissue samples were obtained from patients with HB. The results of the present study showed that a significantly higher level of KLK4 mRNA expression levels were detected in HB tissues, as compared with the matched controls. Furthermore, the KLK4 gene promoter region was distinctively less methylated in the HB samples compared with the controls and negatively correlated with KLK4 mRNA expression levels. These findings indicate that aberrant methylation of KLK4 may contribute to its upregulated mRNA expression in HB.

Genome-wide analysis of DNA methylation in hepatoblastoma tissues.

DNA methylation has a crucial role in cancer biology. In the present study, a genome-wide analysis of DNA methylation in hepatoblastoma (HB) tissues was performed to verify differential methylation levels between HB and normal tissues. As alpha-fetoprotein (AFP) has a critical role in HB, AFP methylation levels were also detected using pyrosequencing. Normal and HB liver tissue samples (frozen tissue) were obtained from patients with HB. Genome-wide analysis of DNA methylation in these tissues was performed using an Infinium HumanMethylation450 BeadChip, and the results were confirmed with reverse transcription-quantitative polymerase chain reaction. The Infinium HumanMethylation450 BeadChip demonstrated distinctively less methylation in HB tissues than in non-tumor tissues. In addition, methylation enrichment was observed in positions near the transcription start site of AFP, which exhibited lower methylation levels in HB tissues than in non-tumor liver tissues. Lastly, a significant negative correlation was observed between AFP messenger RNA expression and DNA methylation percentage, using linear Pearson's R correlation coefficients. The present results demonstrate differential methylation levels between HB and normal tissues, and imply that aberrant methylation of AFP in HB could reflect HB development. Expansion of these findings could provide useful insight into HB biology.

Antitumor activity of YM155, a selective survivin suppressant, in combination with cisplatin in hepatoblastoma.

Cisplatin (CDDP) is a chemotherapeutic drug that is often used for the treatment of hepatoblastoma. However, many patients acquire resistance to therapeutic agents leading to local and distant treatment failure. It has been shown that suppression survivin contributed to the inhibition of tumor growth and enhanced chemotherapeutic sensitivity in several types of cancer. The aim of the present study was to determine whether treatment with sepantronium bromide (YM155), a novel small molecule inhibitor of survivin, enhanced the sensitivity of CDDP to hepatoblastoma cells, leading to the therapeutic efficacy of cisplatin. In vitro and in vivo models were used to examine the anticancer efficacy of YM155, either as a monotherapy or in combination with CDDP to identify more effective therapeutics against hepatoblastoma. The results showed that survivin expression was upregulated in hepatoblastoma tissues and cell lines, and that YM155 inhibited survivin expression in hepatoblastoma cells in a dose-dependent manner. YM155 enhanced sensitivity of CDDP to human HepG2 and HuH-6 hepatoblastoma cells. The YM155 combination with CDDP in hepatoblastoma cells significantly decreased cell proliferation and formation, and induced cell apoptosis than either agent alone. In a mouse xenograft model, YM155 combined with CDDP significantly suppressed tumor growth compared to the monotherapy. Taken together, these findings suggested that the combination of YM155 and CDDP is a promising drug candidate for the treatment of hepatoblastoma.

Clinical significance of CD44 expression in children with hepatoblastoma.

The aim of this study was to investigate the expression of CD44 and its clinical significance in children suffering from hepatoblastoma (HB). CD44 expression was detected with immunohistochemistry staining in 30 samples from hepatoblastoma children and 10 normal liver tissue samples from normal children. The data obtained was statistically analyzed using the chi-square test, using the SPSS (v.11.0) software. The rate of CD44 expression was significantly higher (66.7%) in hepatoblastoma tissues than in normal liver tissues (χ(2) = 4.848, P < 0.05). The rate of CD44 expression was significantly higher in children with stage III or IV hepatoblastoma (83.3%) than that in children with stage I and II hepatoblastoma (χ(2) ＝ 5.625, P < 0.05) (41.7%). Therefore, CD44 expression might play an important role in the pathogenesis, progression, and prognosis of HB in children.

Activation of β-Catenin and Yap1 in Human Hepatoblastoma and Induction of Hepatocarcinogenesis in Mice

Aberrant activation of β-catenin and Yes-associated protein 1 (Yap1) signaling pathways have been associated with the development of multiple tumor types. Yap functions as a transcriptional coactivator by interacting with TEA domain DNA binding proteins. We investigated the interactions among these pathways during hepatic tumorigenesis. We used immunohistochemical analysis to determine expression of β-catenin and Yap1 in liver cancer specimens collected from patients in Europe and the United States, consisting of 104 hepatocellular carcinoma, 62 intrahepatic cholangiocarcinoma, and 94 hepatoblastoma samples. We assessed β-catenin and Yap1 signaling and interactions in hepatoblastoma cell lines ((HuH6, HepG2, HepT1, HC-AFW1, HepG2, and HC-AFW1); proteins were knocked down with small interfering RNAs, and effects on proliferation and cell death were measured. Sleeping beauty-mediated hydrodynamic transfection was used to overexpress constitutively active forms of β-catenin (ΔN90/β-catenin) and Yap1 (YapS127A) in livers of mice; tissues were collected, and histological and immunohistochemical analyses were performed. We observed nuclear localization of β-catenin and Yap1 in 79% of hepatoblastoma samples but not in most hepatocellular carcinoma or intrahepatic cholangiocarcinoma samples. Yap1 and β-catenin coprecipitated in hepatoblastoma but not hepatocellular carcinoma cells. Small interfering RNA-mediated knockdown of Yap1 or β-catenin in hepatoblastoma cells reduced proliferation in an additive manner. Knockdown of Yap1 reduced its ability to coactivate transcription with β-catenin; β-catenin inhibitors inactivated Yap1. Overexpression of constitutively active forms of Yap1 and β-catenin in mouse liver led to rapid tumorigenesis, with 100% mortality by 11 weeks. Tumor cells expressed both proteins, and human hepatoblastoma cells expressed common targets of their 2 signaling pathways. Yap1 binding of TEA domain factors was required for tumorigenesis in mice. β-catenin and the transcriptional regulator Yap1 interact physically and are activated in most human hepatoblastoma tissues; overexpression of activated forms of these proteins in livers of mice leads to rapid tumor development. Further analysis of these mice will allow further studies of these pathways in hepatoblastoma pathogenesis and could lead to the identification of new therapeutic targets.

Genome-Wide Analysis of Long Noncoding RNA (lncRNA) Expression in Hepatoblastoma Tissues

Long noncoding RNAs (lncRNAs) have crucial roles in cancer biology. We performed a genome-wide analysis of lncRNA expression in hepatoblastoma tissues to identify novel targets for further study of hepatoblastoma. Hepatoblastoma and normal liver tissue samples were obtained from hepatoblastoma patients. The genome-wide analysis of lncRNA expression in these tissues was performed using a 4×180 K lncRNA microarray and Sureprint G3 Human lncRNA Chips. Quantitative RT-PCR (qRT-PCR) was performed to confirm these results. The differential expressions of lncRNAs and mRNAs were identified through fold-change filtering. Gene Ontology (GO) and pathway analyses were performed using the standard enrichment computation method. Associations between lncRNAs and adjacent protein-coding genes were determined through complex transcriptional loci analysis. We found that 2736 lncRNAs were differentially expressed in hepatoblastoma tissues. Among these, 1757 lncRNAs were upregulated more than two-fold relative to normal tissues and 979 lncRNAs were downregulated. Moreover, in hepatoblastoma there were 420 matched lncRNA-mRNA pairs for 120 differentially expressed lncRNAs, and 167 differentially expressed mRNAs. The co-expression network analysis predicted 252 network nodes and 420 connections between 120 lncRNAs and 132 coding genes. Within this co-expression network, 369 pairs were positive, and 51 pairs were negative. Lastly, qRT-PCR data verified six upregulated and downregulated lncRNAs in hepatoblastoma, plus endothelial cell-specific molecule 1 (ESM1) mRNA. Our results demonstrated that expression of these aberrant lncRNAs could respond to hepatoblastoma development. Further study of these lncRNAs could provide useful insight into hepatoblastoma biology.

Inhibition of autophagy may suppress the development of hepatoblastoma

Hepatoblastoma (HB) is a rare cancer but represents the most common liver malignancy in children under 3 years of age. Nevertheless, a clear understanding of the pathogenesis is lacking. Although the treatment of HB has been dramatically improved by combining chemotherapy regimens with surgery, its fatal outcome of fast development and recurrence makes new treatment strategies for HB, based on an improved understanding of the pathogenesis, essential. Autophagy is believed to be important in the progression of cancers. However, the role of autophagy in HB remains to be elucidated. Here, we show that autophagy is activated in HB tissues and cells under the conditions of starvation or chemotherapy, coupled with the over-expression of autophagic-related genes BECN1 and ATG5. Suppression of autophagy with pharmacological agents and small interfering RNAs significantly increased cell apoptosis and retarded proliferation in response to nutrition deprivation and treatment with chemotherapeutics. Our data demonstrate that the BECN1 and ATG5-dependent phosphoinositide 3-kinase (PI3K) signaling pathway is essential for the survival of HB cells and their tolerance to chemotherapy and starvation-induced death, and suggests that modifying such autophagic genes may suppress the development of HB, thus offering a therapeutic potential for patients with HB.

Deregulation of Hippo kinase signalling in Human hepatic malignancies

Hepatocellular carcinoma (HCC), cholangiocarcinoma (CC) and hepatoblastoma (HB) are the main hepatic malignancies with limited treatment options and high mortality. Recent studies have implicated Hippo kinase pathway in cancer development, but detailed analysis of Hippo kinase signalling in human hepatic malignancies, especially CC and HB, is lacking. We investigated Hippo kinase signalling in HCC, CC and HB using cells and patient samples. Increased expression of yes-associated protein (Yap), the downstream effector of the Hippo kinase pathway, was observed in HCC cells, and siRNA-mediated knockdown of Yap resulted in decreased survival of HCC cells. The density-dependent activation of Hippo kinase pathway characteristic of normal cells was not observed in HCC cells and CCLP cells, a cholangiocarcinoma cell line. Immunohistochemistry of Yap in HCC, CC and HB tissues indicated extensive nuclear localization of Yap in majority of tissues. Western blot analysis performed using total cell extracts from patient samples and normal livers showed extensive activation of Yap. Marked induction of Glypican-3, CTGF and Survivin, the three Yap target genes was observed in the tumour samples. Further analysis revealed significant decrease in expression and activity of Lats kinase, the main upstream regulator of Yap. However, no change in activation of Mst-2 kinase, the upstream regulator of Lats kinase was observed. These data show that Yap induction mediated by inactivation of Lats is observed in hepatic malignancies. These studies highlight Hippo kinase pathway as a novel therapeutic target for hepatic malignancies.

Optimizing vector application for gene transfer into human hepatoblastoma cells

Gene targeting is currently of distinct interest as an innovative additive treatment option in various malignancies. Its role in pediatric liver tumors has not yet been evaluated thoroughly. For the first time the authors systematically analyzed both lipid-based transfection as well as transduction with adenovirus vectors (Ad) and Sendai virus vectors (SeVV) in order to optimize gene transfer into hepatoblastoma (HB) cells. Two HB cell lines were infected with Ad or SeVV coding for green fluorescent protein (Ad-GFP, SeVV-GFP); transduction efficiencies and apoptosis were assessed using flow cytometry. Furthermore, lipofection of HB cell lines with plasmid-constructs comprising liver-specific promoters was performed using Lipofectamine 2000 and FuGENE 6; lipofection efficiency was monitored by flow cytometry, microscopy, and luciferase activity. The Ad-GFP showed higher transduction rates (61-86%) than the SeVV-GFP (4-24%) depending on the HB cell line used. Infections with first generation SeVV vectors (SeVV-GFP) led to increased target cell apoptosis (7-43%) compared to Ad-GFP (4-16%). The Lipofectamine 2000 revealed a higher transfection efficiency than the FuGENE 6 for both HB cell lines tested. The liver-specific promoters were found to be differently active in the HB cell lines. This study delineates recombinant adenovirus vectors as a promising tool for gene transduction in the HB cells. Furthermore, enhanced activity of the liver-specific promoters in HUH6 cells compared to HepT1 cells supports the observation of varying biological behavior in histologically differing HB tissues.

β-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.

High expression of telomerase is an independent prognostic indicator of poor outcome in hepatoblastoma

Telomerase, an enzyme related with cellular immortality, has been extensively studied in many kinds of malignant tumours for clinical diagnostic or prognostic utilities. Telomerase activity is mainly regulated by the expression of hTERT (human telomerase reverse transcriptase), which is a catalytic component of human telomerase. To evaluate whether the levels of hTERT mRNA provides a molecular marker of hepatoblastoma malignancy, we examined hTERT mRNA expression levels in the primary hepatoblastoma tissues by fluorescent RT–PCR using LightCycler technology and followed up the clinical outcomes in 63 patients listed in the Japanese Study Group of Pediatric Liver Tumor between 1991 and 2002. The hTERT mRNA expression was detected in 61 (96.8%) specimens and their expression levels ranged between 0.1/1000 and 745.1/1000 copies of PBGD gene that was used as an internal control. Among these cases, frozen 39 tumour samples and 14 adjacent noncancerous liver tissues were analysed for semiquantitative telomerase assay. In the 39 tumour samples, the levels of telomerase activity ranged between 0.11 and 2709 TPG and 12 (30.7%) had high telomerase activity (>100 TPG), whereas only nine of 14 noncancerous liver tissue samples showed telomerase activity which was less than 1.0 TPG. The levels of telomerase activity were significantly correlated with the levels of hTERT mRNA expression (P<0.001). The frequency of high hTERT mRNA expression and/or high telomerase activity did not significantly associate with the clinicopathological factors except for stage of disease. The prognosis of the patients with high hTERT mRNA expression was significantly worse than that of others (P<0.01), as was the patients with high telomerase activity (P<0.01). Multivariate analysis indicated that high levels of hTERT mRNA expression as well as telomerase activity are independent prognosis-predicting factors in patients with hepatoblastoma.

Thrombopoietin in patients with hepatoblastoma.

Marked thrombocytosis (over 50 x 10(4)/microl) is frequently seen in patients with hepatoblastoma. Thrombopoietin (TPO), c-mpl ligand, has recently been purified as the major physiological regulator of the thrombopoiesis and is mainly produced in the liver. Since it is possible that TPO participates in thrombocytosis and the tumor growth of this particular hepatic tumor, serum TPO levels in addition to interleukin 1beta (IL-1beta) and IL-6 levels were assessed in seven untreated patients by using a sandwich enzyme-linked immunosorbent assay. High serum TPO levels were observed in all of the examined patients. The level ranged from 3.15 to 11.02 (mean +/- standard deviation; 6.08+/-1.25) fmol/ml. IL-6 levels were also somewhat higher than normal. Platelet counts, however, appeared to correlate more with serum TPO levels (p = 0.1) than with IL-1beta (p = 0.5) and IL-6 (p = 0.2) levels. Furthermore, using the reverse transcriptase polymerase chain reaction method, the expression of c-mpl mRNA was found in five of eight hepatoblastoma tissues as well as TPO mRNA in all eight tissues. These observations suggest that thrombocytosis in hepatoblastoma patients results from the production of cytokine members, including TPO, within tumor tissues. Additionally, it is possible that TPO might act as a type of autocrine and/or paracrine system for cellular growth in this tumor.

ImmunohistochemicaI and UItrastructuraI LocaIization of Epidermal Growth Factor Receptor in Human Liver and Hepatocellular Carcinoma Tissues

Expression of epidermal growth factor receptor (EGF-R) in human hepatocellular carcinoma (HCC), hepatoblastoma and non-cancerous liver tissues was investigated immunohistochemically in order to evaluate the possible role of EGF-R expression in neoplastic transformation of hepatocytes. Immunoreactive EGF-R molecules were identified on frozen sections by means of the avidin-biotin immunoperoxidase complex technique using a monoclonal antibody recognizing an epitope of the external domain of human EGF-R. Linear positive staining was present on the surface of carcinoma cells in one hepatoblastoma and in 9 of 11 HCCs. In addition, an enhanced level of surface EGF-R expression was observed on the tumor cells in 9 of 12 cases in comparison with that on hepatocytes in surrounding non-cancerous liver tissue, which in most cases showed chronic inflammation, hepatocyte injury or regeneration. No positive staining in the form of coalescent cytoplasmic granules was present in HCC or hepatoblastoma cells, nor in the cytoplasm of hepatocytes in normal or non-cancerous diseased liver tissue. Little or no reactivity was present on the surface membrane of hepatocytes in the normal liver tissues of 8 control cases. Furthermore, immunoelectron microscopy revealed the localization of this immunoreactive EGF-R molecule on the plasma membrane. Considering that the functional form of EGF-R could be localized on the plasma membrane, the enhanced expression of immunoreactive EGF-R on the tumor cell surface demonstrated here may suggest a possible role of EGF-R in the development or progression of human HCC as well as in hepatocyte regeneration.