Activation of fetal promoters of insulinlike growth factors II gene in hepatitis C virus-related chronic hepatitis, cirrhosis, and hepatocellular carcinoma

Human IGF2 Gene Epigenetic and Transcriptional Regulation: At the Core of Developmental Growth and Tumorigenic Behavior

Regulation of the human IGF2 gene displays multiple layers of control, which secures a genetically and epigenetically predetermined gene expression pattern throughout embryonal growth and postnatal life. These predominantly nuclear regulatory mechanisms converge on the function of the IGF2-H19 gene cluster on Chromosome 11 and ultimately affect IGF2 gene expression. Deregulation of such control checkpoints leads to the enhancement of IGF2 gene transcription and/or transcript stabilization, ultimately leading to IGF-II peptide overproduction. This type of anomaly is responsible for the effects observed in terms of both abnormal fetal growth and increased cell proliferation, typically observed in pediatric overgrowth syndromes and cancer. We performed a review of relevant experimental work on the mechanisms affecting the human IGF2 gene at the epigenetic, transcriptional and transcript regulatory levels. The result of our work, indeed, provides a wider and diversified scenario for IGF2 gene activation than previously envisioned by shedding new light on its extended regulation. Overall, we focused on the functional integration between the epigenetic and genetic machinery driving its overexpression in overgrowth syndromes and malignancy, independently of the underlying presence of loss of imprinting (LOI). The molecular landscape provided at last strengthens the role of IGF2 in cancer initiation, progression and malignant phenotype maintenance. Finally, this review suggests potential actionable targets for IGF2 gene- and regulatory protein target-degradation therapies.

Relationship between Metal Pollution and Gene Expression of Insulin-like Growth Factor II

BACKGROUND

Metals pollution plays an important role in the regulation of gene expression through interference with signal transduction pathways which are important for cell bioactivity.

OBJECTIVES

The present study was conducted to estimate metallothionein levels in mussels as a biomarker of exposure to heavy metals in order to monitor the pollution of Abu Qir Bay, Egypt (El-Maadiya region) and to evaluate the impact of heavy metals on human health by examining insulin-like growth factor II (IGF-2) gene expression in peripheral blood mononuclear cells.

METHODS

One hundred and forty mussel samples (Andara dulofii) were collected from Abu-Qir Bay, stored in bags, preserved in an ice box, and then transported to the laboratory to acclimatize at 20°C for three days in ethylene diamine tetra acetic acid (EDTA)-free synthetic sea water to determine the presence of metallothionein and five other metals (cadmium (Cd), lead (Pb), chromium (Cr), copper (Cu) and zinc (Zn)).

RESULTS

Results showed that mussels collected from the study area contained a measurable amount of metallothionein. In addition, results revealed an increased level of malondialdehyde coinciding with a decreased level of antioxidants, leading to oxidative stress in local fishermen.

CONCLUSIONS

The present data demonstrated a significant increase in the gene expression of IGF-2 and a positive correlation between IGF-2 gene expression and the enzymatic activity of glutathione peroxidase in male subjects.

PARTICIPANT CONSENT

Obtained.

ETHICS APPROVAL

Written consent was provided by the study participants and study approval was given by the ethics committee of Alexandria University (US Department of Health and Human Services, Registration of an Institutional Review Board, IORG0008812 Medical Research Institute, Expires 4/8/2019, OMB No:0990-0279).

COMPETING INTERESTS

The authors declare no competing financial interests.

Cytotoxic and partial hepatoprotective activity of sodium ascorbate against hepatocellular carcinoma through inhibition of sulfatase-2 in vivo and in vitro

Hepatocellular carcinoma (HCC) is characterized by elevation in the activity of sulfatase-2, an extracellular enzyme that catalyzes removal of 6-O-sulfate groups from heparan sulfate. Therefore, we conducted this study to investigate the cytotoxic activity of the strong water-soluble antioxidant, sodium ascorbate, against HCC both in vivo and in vitro. Sodium ascorbate enhanced animal survival in vivo and reduced HepG2 cells survival. The protein levels of heparan sulfate proteoglycans (HSPGs), insulin like growth factor (IGF)-2, sulfatase-2 and glypican-3 were assessed. Inflammation was evaluated by measuring the gene and protein expression of NFκB, TNF-α, IL-1β, IL-4, IL-6 and IL-10. We found that sodium ascorbate blocked HCC-induced activation of sulfatase-2 leading to restoration of HSPGs receptors associated with reduction in IGF-2 and glypican-3. Sodium ascorbate exerts anti-inflammatory activity by reducing the expression of NFκB, CRP, TNF-α, IL-1β and IL-6 associated with enhanced expression of the anti-inflammatory cytokines, IL-4 and IL-10. In conclusion, cytotoxic effects of sodium ascorbate against HCC can be partially explained by inhibition of sulfatase-2, restoration of HSPGs receptors and deactivation of the inflammatory pathway.

Glypican-3 induces oncogenicity by preventing IGF-1R degradation, a process that can be blocked by Grb10

Hepatocellular carcinoma (HCC) is the most common primary liver malignancy and is a major cause of cancer-related death worldwide. Previously, we demonstrated that glypican-3 (GPC3) is highly expressed in HCC, and that GPC3 induces oncogenicity and promotes the growth of cancer cells through IGF-1 receptor (IGF-1R). In the present study, we investigated the mechanisms of GPC3-mediated enhancement of IGF-1R signaling. We demonstrated that GPC3 decreased IGF-1-induced IGF-1R ubiquitination and degradation and increased c-Myc protein levels. GPC3 bound to Grb10, a mediator of ligand-induced receptor ubiquitination, and the overexpression of Grb10 blocked GPC3-enhanced IGF-1-induced ERK phosphorylation. GPC3 promoted the growth of NIH3T3 and PLC-PRF-5 cells in serum-free medium but did not promote the growth of IGF-1R negative R- cells. Grb10 overexpression decreased GPC3-promoted cell growth. Therefore, the present study elucidates the mechanisms of GPC3-induced oncogenicity, which may highlight new strategies for the treatment of HCC.

Evaluation of antiglypican-3 therapy as a promising target for amelioration of hepatic tissue damage in hepatocellular carcinoma

In Egypt, hepatocellular carcinoma (HCC) was predicted to continue to rise over the next few decades causing a national problem. Meanwhile, glypican-3 (GPC3), a highly expressed glypican, has emerged as a potential target for HCC immunotherapy. Therefore, we aimed to identify the impact of blocking GPC3 on liver damage in HCC as well as a possible mechanism. Fifty four HCC patients, 20 cirrhotic patients and 10 healthy subjects were recruited. Serum levels of GPC3, sulfatase-2 (SULF-2), heparan sulfate proteoglycan (HSPG), insulin-like growth factor-II (IGF-II) were measured by ELISA. In parallel, HCC was induced in 40 male Sprague-Dawley rats in presence/absence of antiGPC-3. Liver impairment was detected by investigating liver sections stained with hematoxylin/eosin and serum α-fetoprotein (AFP). Liver homogenates of GPC3, SULF-2, and HSPG were measured by ELISA. Gene expression of caspase-3 and IGF-II were assayed by RT-PCR. HCC patients showed significant elevated serum levels of GPC3, IGF-II and SULF-2 accompanied by decreased HSPG. However, treatment of HCC rats with antiGPC-3 significantly reduced serum AFP and showed nearly normal hepatocytes. In addition, antiGPC-3 significantly reduced elevated liver homogenates protein levels of GPC3 and SULF-2 and gene expression of IGF-II and caspase-3. antiGPC-3 restored the reduced hepatic HSPG. antiGPC-3 showed anti-tumor activity as well as hepatoprotective effects. antiGPC-3-chemoprotective effect can be explained by forced reduction of IGF-II expression, restoration of HSPGs, deactivation of SULF-2 and reduction of gene expression of caspase-3. Targeting GPC3 is a promising therapeutic approach for HCC.

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

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

Notch signaling is activated in human hepatocellular carcinoma and induces tumor formation in mice

BACKGROUND & AIMS

The Notch signaling pathway is activated in leukemia and solid tumors (such as lung cancer), but little is known about its role in liver cancer.

METHODS

The intracellular domain of Notch was conditionally expressed in hepatoblasts and their progeny (hepatocytes and cholangiocytes) in mice. This was achieved through Cre expression under the control of an albumin and α-fetoprotein (AFP) enhancer and promoter (AFP-Notch intracellular domain [NICD]). We used comparative functional genomics to integrate transcriptome data from AFP-NICD mice and human hepatocellular carcinoma (HCC) samples (n = 683). A Notch gene signature was generated using the nearest template prediction method.

RESULTS

AFP-NICD mice developed HCC with 100% penetrance when they were 12 months old. Activation of Notch signaling correlated with activation of 3 promoters of insulin-like growth factor 2; these processes appeared to contribute to hepatocarcinogenesis. Comparative functional genomic analysis identified a signature of Notch activation in 30% of HCC samples from patients. These samples had altered expression in Notch pathway genes and activation of insulin-like growth factor signaling, despite a low frequency of mutations in regions of NOTCH1 associated with cancer. Blocking Notch signaling in liver cancer cells with the Notch activation signature using γ-secretase inhibitors or by expressing a dominant negative form of mastermind-like 1 reduced their proliferation in vitro.

CONCLUSIONS

Notch signaling is activated in human HCC samples and promotes formation of liver tumors in mice. The Notch signature is a biomarker of response to Notch inhibition in vitro.

The insulin-like growth factor (IGF) signaling axis and hepatitis C virus-associated carcinogenesis (review)

Insulin-like growth factor (IGF) signaling plays an important autocrine, paracrine and endocrine role in growth promotion involving various tissues and organs. Synthesis of both IGFs (IGF-1 and IGF-2) in normal conditions takes place mainly in the liver even if the proteins can be produced in every cell of the human body. The alterations in the IGF signaling axis in human hepatocarcinogenesis are described, but mechanisms of the interactions between expression of oncogenic hepatitis C virus (HCV) proteins and components of the IGF system in progression of chronic hepatitis C to primary hepatocellular carcinoma (HCC) have been poorly recognised. In advanced stages of liver diseases, lowered serum levels of IGF-1 and IGF-2 have been documented. This was supposed to reflect significant damage to liver parenchyma, a decreased number of growth hormone receptors and a decreased genomic expression of IGF binding proteins (IGF BPs). In HCC, a decreased tissue expression of IGF-1, and an increased expression of IGF-1 receptor (IGF-1R) were noted, compared to the control. Potential mechanisms of augmented IGF-2 expression in HCC were also described and dysregulation of IGF signaling in HCC was concluded to occur predominantly at the level of IGF-2 bioavailability. The review aimed at presentation of involvement of IGF-1, IGF-1R and IGF BPs (mostly IGF BP-3 and IGF BP-6) in HCV-related hepatocarcinogenesis. Manifestation of various mRNA transcripts and IGF-1 proteins and their potential involvement in carcinogenesis are also discussed.

Insulin-like growth factor II in hepatocellular carcinoma

Hepatocellular carcinoma is one of the most common malignant human tumors. Hepatocarcinogenesis is a multistep process with a multifactorial etiology. Chronic hepatitis B and hepatitis C virus infection, alcohol drinking and cirrhosis of any etiology are the major risk factors for hepatocellular carcinoma. Growth factors, their receptors and related proteins are involved in the process of malignant transformation. The IGF axis is involved in the proliferation and differentiation of normal, transformed and malignant hepatocytes. In the context of hepatocarcinogenesis, IGF-II has, in particular, been investigated thoroughly. Increased IGF-II bioavailability, protease activity of IGF-binding proteins and IGF-I receptor expression, decreased expression of IGF-II receptor and IGF-binding proteins are thought to contribute to hepatocellular carcinoma genesis. This review will first focus on the role of the IGF axis in hepatocarcinogenesis. In the second part it will emphasize circulating IGF-II levels in chronic liver disease and hepatocellular carcinoma, and diagnostic application of serum IGF-II level in both small and larger hepatocellular carcinoma.

IGF activation in a molecular subclass of hepatocellular carcinoma and pre-clinical efficacy of IGF-1R blockage

BACKGROUND & AIMS

IGF signaling has a relevant role in a variety of human malignancies. We analyzed the underlying molecular mechanisms of IGF signaling activation in early hepatocellular carcinoma (HCC; BCLC class 0 or A) and assessed novel targeted therapies blocking this pathway.

METHODS

An integrative molecular dissection of the axis was conducted in a cohort of 104 HCCs analyzing gene and miRNA expression, structural aberrations, and protein activation. The therapeutic potential of a selective IGF-1R inhibitor, the monoclonal antibody A12, was assessed in vitro and in a xenograft model of HCC.

RESULTS

Activation of the IGF axis was observed in 21% of early HCCs. Several molecular aberrations were identified, such as overexpression of IGF2 -resulting from reactivation of fetal promoters P3 and P4-, IGFBP3 downregulation and allelic losses of IGF2R (25% of cases). A gene signature defining IGF-1R activation was developed. Overall, activation of IGF signaling in HCC was significantly associated with mTOR signaling (p=0.035) and was clearly enriched in the Proliferation subclass of the molecular classification of HCC (p=0.001). We also found an inverse correlation between IGF activation and miR-100/miR-216 levels (FDR<0.05). In vitro studies showed that A12-induced abrogation of IGF-1R activation and downstream signaling significantly decreased cell viability and proliferation. In vivo, A12 delayed tumor growth and prolonged survival, reducing proliferation rates and inducing apoptosis.

CONCLUSIONS

Integrative genomic analysis showed enrichment of activation of IGF signaling in the Proliferation subclass of HCC. Effective blockage of IGF signaling with A12 provides the rationale for testing this therapy in clinical trials.

Glypican-3-mediated oncogenesis involves the Insulin-like growth factor-signaling pathway

Glypican-3 (gpc3) is the gene responsible for Simpson-Golabi-Behmel overgrowth syndrome. Previously, we have shown that GPC3 is overexpressed in hepatocellular carcinoma (HCC). In this study, we demonstrated the mechanisms for GPC3-mediated oncogenesis. Firstly, GPC3 overexpression in NIH3T3 cells gave to cancer cell phenotypes including growing in serum-free medium and forming colonies in soft agar, or on the other way, GPC3 knockdown in HuH-7 cells decreased oncogenecity. We further demonstrated that GPC3 bound specifically through its N-terminal proline-rich region to both Insulin-like growth factor (IGF)-II and IGF-1R. GPC3 stimulated the phosphorylation of IGF-1R and the downstream signaling molecule extracellular signal-regulated kinase (ERK) in an IGF-II-dependent way. Also, GPC3 knockdown in HCC cells decreased the phosphorylation of both IGF-1R and ERK. Therefore, GPC3 confers oncogenecity through the interaction between IGF-II and its receptor, and the subsequent activation of the IGF-signaling pathway. This data are novel to the current understanding of the role of GPC3 in HCC and will be important in future developments of cancer therapy.

Hepatitis C virus core protein induces spontaneous and persistent activation of peroxisome proliferator-activated receptor alpha in transgenic mice: implications for HCV-associated hepatocarcinogenesis

Persistent infection of hepatitis C virus (HCV) can lead to a high risk for hepatocellular carcinoma (HCC). HCV core protein plays important roles in HCV-related hepatocarcinogenesis, because mice carrying the core protein exhibit multicentric HCCs without hepatic inflammation and fibrosis. However, the precise mechanism of hepatocarcinogenesis in these transgenic mice remains unclear. To evaluate whether the core protein modulates hepatocyte proliferation and apoptosis in vivo, we examined these parameters in 9- and 22-month-old transgenic mice. Although the numbers of apoptotic hepatocytes and hepatic caspase 3 activities were similar between transgenic and nontransgenic mice, the numbers of proliferating hepatocytes and the levels of numerous proteins such as cyclin D1, cyclin-dependent kinase 4 and c-Myc, were markedly increased in an age-dependent manner in the transgenic mice. This increase was correlated with the activation of peroxisome proliferator-activated receptor alpha (PPARalpha). In these transgenic mice, spontaneous and persistent PPARalpha activation occurred heterogeneously, which was different from that observed in mice treated with clofibrate, a potent peroxisome proliferator. We further demonstrated that stabilization of PPARalpha through a possible interaction with HCV core protein and an increase in nonesterified fatty acids, which may serve as endogenous PPARalpha ligands, in hepatocyte nuclei contributed to the core protein-specific PPARalpha activation. In conclusion, these results offer the first suggestion that HCV core protein induces spontaneous, persistent, age-dependent and heterogeneous activation of PPARalpha in transgenic mice, which may contribute to the age-dependent and multicentric hepatocarcinogenesis mediated by the core protein.

Screening candidate longevity therapeutics using gene-expression arrays

BACKGROUND

We review studies showing that CR acts rapidly, even in late adulthood, to extend health- and lifespan in mice. These rapid physiological effects are closely linked to patterns of gene expression in liver and heart. Non-human primate and human studies suggest that the signal transduction pathways responsible for the lifespan and health effects of caloric restriction (CR) may also be involved in human longevity. Thus, pharmaceuticals capable of mimicking the effects of CR (and other methods of lifespan extension) may have application to human health.

OBJECTIVE

We show that lifespan studies are an inefficient and theoretically problematic way of screening for longevity therapeutics. We review studies suggesting that rapid changes in patterns of gene expression can be used to identify pharmaceuticals capable of mimicking some positive effects of caloric restriction.

RESULTS

We present a traditional study of the effects of melatonin, melatonin and pregnenolone, aminoguanidine, aminoguanidine and alpha-lipoic acid, aminoguanidine, alpha-lipoic acid, pregnenolone, and coenzyme-Q(10) on the lifespan of mice. No treatment extended lifespan. However, because the mice die mostly of cancer, only chemopreventives active against specific cancers can be identified by such studies. The studies were also time-consuming and expensive. We discuss high-density microarray studies of the effectiveness of glucoregulatory drugs and putative cancer chemopreventatives at reproducing the hepatic gene-expression profiles of long-term and short-term CR. We describe the identification of one compound, metformin, which reproduces a subset of the gene-expression and physiological effects of CR.

CONCLUSION

Taken together, our results suggest that gene-expression biomarkers may be superior to lifespan studies for initial screening of candidate longevity therapeutics.

Pleiotropic effects of PI-3' kinase/Akt signaling in human hepatoma cell proliferation and drug-induced apoptosis

IGF-II and type I-IGF receptor (IGF-IR) gene expression is increased in primary liver tumors, and transgenic mice overexpressing IGF-II in the liver develop hepatocellular carcinoma (HCC) spontaneously, suggesting that alterations of IGF-IR signaling in vivo may play a role in the auto/paracrine control of hepatocarcinogenesis. We have addressed the contribution of PI-3'K/Akt signaling on the proliferation of HepG2 human hepatoma cells and on their protection against doxorubicin-induced apoptosis. Both basal HepG2 cell DNA replication and that stimulated by IGF-IR signaling were inhibited by the specific PI-3'K inhibitor Ly294002 (Ly). In the former case, PI-3'K signaling overcame cell cycle arrest in G1 via increased cyclin D1 protein and decreased p27kip1 gene expression. Doxorubicin treatment induced apoptosis in HepG2 cells and was concomitant with the proteolytic cleavage of Akt-1 and -2. Drug-induced apoptosis was reversed by IGF-I and this effect was (i) dependent on Akt-1 and -2 phosphorylation and (ii) accompanied by the inhibition of initiator caspase-9 activity, suggesting that IGF-IR signaling interferes with mitochondria-dependent apoptosis. Accordingly, Ly enhanced doxorubicin-induced apoptosis and suppressed its reversal by IGF-I. Altogether, the data emphasize the crucial role of PI-3'K/Akt signaling (i) in basal as well as IGF-IR-stimulated HepG2 cell proliferation and (ii) in controlling both doxorubicin-induced apoptosis (e.g., drug-induced cleavage of Akt) and its reversal by IGF-I (protection against apoptosis parallels the extent of Akt phosphorylation). They suggest that targeting Akt activity or downstream Akt effectors (e.g., GSK3-beta, FOXO transcription factors) may help define novel therapeutic strategies of increased efficacy in the treatment of HCC-bearing patients.

Hypomethylated P4 promoter induces expression of the insulin-like growth factor-II gene in hepatocellular carcinoma in a Chinese population

PURPOSE

The expression of human insulin-like growth factor-II (IGF-II) is regulated by the activation of four promoters (P1-P4) acting in a development-dependent, tissue-specific manner. IGF-II overexpression associated with P3 and P4 activation is observed in animal and human hepatocarcinogenesis. We correlated P4 epigenetic alteration with P4 transcript activation and clinicopathologic features.

EXPERIMENTAL DESIGN

We analyzed P4 epigenetic alteration using methylation-specific PCR in 34 hepatocellular carcinoma (HCC) specimens, 34 matched adjacent nontumor specimens, and 8 normal adult liver specimens. The data were correlated with activation of P4 transcription by using reverse transcription-PCR. Epigenetic alteration was compared with patients' clinicopathologic features.

RESULTS

Compared with normal liver tissue, hypomethylation of P4 CpG islands was significantly more frequent in HCC (P = 0.03) and matched tissues (P = 0.047). P4 mRNA levels in HCC with unmethylated alleles were significantly higher than in HCC without unmethylated alleles (P = 0.001); P4 mRNA levels in matched nontumor tissues with unmethylated alleles were significantly higher than in matched nontumor tissues without unmethylated alleles (P = 0.005). P4 hypomethylation in HCC was associated with portal vein tumor embolus (P = 0.017) and poorer tumor differentiation (P = 0.025).

CONCLUSIONS

These findings suggest that IGF-II P4 hypomethylation may be an early and frequent event and that it may contribute to P4 transcription expression activation during the transformation of a premalignant liver lesion to HCC. Furthermore, aberrant hypomethylation of P4 CpG islands not only may play an important role during hepatocarcinogenesis but might also be a useful biomarker for poor prognosis of patients with HCC.

Impact of IGF-1R/EGFR cross-talks on hepatoma cell sensitivity to gefitinib

Epidermal growth factor receptor (EGFR)- and type 1 insulin-like growth factor receptor (IGF-1R)-dependent pathways are up-regulated in hepatocellular carcinoma (HCC), and cross-talks between both pathways have been described in other systems. Gefitinib, a specific EGFR inhibitor, has shown to reduce significantly, although not completely, HCC formation in rat cirrhotic liver. Here, we investigated whether IGF-1R-dependent pathways may interfere with EGFR signalling in hepatoma cells and, if so, whether such cross-talks may affect the antitumoral effect of gefitinib in these cells. We show that the proliferative action of IGF2 in HepG2 and Hep3B cells requires EGFR activation through the autocrine/paracrine release of amphiregulin. Thus, IGF2-induced extracellular signal-regulated kinase activity and DNA synthesis were inhibited by neutralizing antibodies against either EGFR or amphiregulin and by TAPI-1, a pharmalogical inhibitor of tumor necrosis factor-alpha converting enzyme, a sheddase of amphiregulin. Accordingly, IGF2 and EGF stimulating effects on cell proliferation were both strongly repressed by gefitinib. However, while gefitinib blocked Akt activation by EGF, it had no effect on Akt activation by IGF2 and did not cause apoptosis by its own. AG1024, a selective IGF-1R inhibitor, induced apoptosis and this effect was potentiated by gefitinib. In conclusion, we show that in HCC cells IGF2/IGF-1R activation triggers proliferative and survival signals through EGFR-dependent and -independent mechanisms, respectively. The IGF2/IGF-1R survival pathway may contribute to gefitinib resistance in these cells. Therefore, the inhibition of IGF2/IGF-1R signalling could potentiate the anti-tumoral effect of gefinitib in HCC.

Aspartyl-asparagyl beta hydroxylase over-expression in human hepatoma is linked to activation of insulin-like growth factor and notch signaling mechanisms

Aspartyl-(asparagyl)-beta-hydroxylase (AAH) is overexpressed in various malignant neoplasms, including hepatocellular carcinomas (HCCs). The upstream regulation of AAH and its functional role in Notch-mediated signaling and motility in HCC cells was accessed. The mRNA transcript levels of AAH, insulin receptor substrate (IRS), insulin and insulin-like growth factor (IGF) receptors and polypeptides, Notch, Jagged, and HES were measured in 15 paired samples of HCC and adjacent HCC-free human liver biopsy specimens using real-time quantitative RT-PCR and Western blot analysis. Overexpression of AAH was detected in 87% of the HCC relative to the paired HCC-free liver tissue. IRS-1, IRS-2, and IRS-4 were each overexpressed in 80% of the HCC samples, and IGF-I and IGF-2 receptors were overexpressed in 40% and 100% of the HCCs, respectively. All HCC samples had relatively increased levels of Notch-1 and HES-1 gene expression. Overexpression of AAH led to increased levels of Notch, and co-immunoprecipitation experiments demonstrated a direct interaction between AAH and Notch as well as its ligand Jagged. In conclusion, contributions to the malignant phenotype of HCC is due to activation of IGF-I and IGF-II signaling that results in over-expression of both AAH and Notch. The functional role of AAH in relation to cell motility has been linked to increased activation of the Notch signaling pathway.

Dysregulation of growth factor signaling in human hepatocellular carcinoma

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

Differential promoter usage for insulin-like growth factor-II gene in Chinese hepatocellular carcinoma with hepatitis B virus infection

BACKGROUND

Human insulin-like growth factor-II (IGF-II) gene contains nine exons and four different promoters (P1-P4). Expression of the gene is elevated in the preneoplastic hepatic foci and hepatocellular carcinoma (HCC) of experimental animals and humans. To gain insight into transcriptional regulation of the gene in HCC, we analyzed the relative usage of the P1-P4 promoters and its correlation with the clinical and pathological characteristics in Chinese hepatocellular carcinoma with hepatitis B virus (HBV) infection.

METHODS

P1-P4 usage levels of the gene in tumorous and matched adjacent nontumorous tissues from 23 HCC patients and 7 normal liver tissues were evaluated using a semiquantitative reverse-transcription polymerase chain reaction (RT-PCR) assay. The mutation status of p53 gene in HCC tissues was analyzed by PCR and sequencing.

RESULTS

Transcripts from P1 were not detectable in 65.2% HCC tissues, and were expressed at low levels or not expressed in all nontumorous tissues compared with normals, but P2 usage levels showed no differences. P3 and P4 expression was significantly increased in most of HCC and almost all adjacent nontumorous tissues. There was a positive association of expression levels of both P3 and P4 transcripts in HCC tissues with the p53 mutation and presence of tumor embolus of portal vein, and expression of P3 were negatively related to differentiation of HCC. However, expression of both P3 and P4 was not associated with other parameters.

CONCLUSIONS

Loss of P1 activity and reactivation of P3 and P4 are important characteristics in most of Chinese HCC with HBV infection, and increased IGF-II expression from P3 and P4 may play an active role in early proliferation of precancerous liver cells and hepatocarcinogenesis of these cases. Significant increase in fetal transcripts is associated with the p53 mutation and poor prognosis of the HCC patients and might serve as one of identification parameters of poor HCC prognosis.

Insulin-like growth factor-I stimulates H4II rat hepatoma cell proliferation: Dominant role of PI-3′K/Akt signaling

Although hepatocytes are the primary source of endocrine IGF-I and -II in mammals, their autocrine/paracrine role in the dysregulation of proliferation and apoptosis during hepatocarcinogenesis and in hepatocarcinomas (HCC) remains to be elucidated. Indeed, IGF-II and type-I IGF receptors are overexpressed in HCC cells, and IGF-I is synthesized in adjacent non-tumoral liver tissue. In the present study, we have investigated the effects of type-I IGF receptor signaling on H4II rat hepatoma cell proliferation, as estimated by 3H-thymidine incorporation into DNA. IGF-I stimulated the rate of DNA synthesis of serum-deprived H4II cells, stimulation being maximal 3 h after the onset of IGF-I treatment and remaining elevated until at least 6 h. The IGF-I-induced increase in DNA replication was abolished by LY294002 and only partially inhibited by PD98059, suggesting that phosphoinositol-3' kinase (PI-3'K) and to a lesser extent MEK/Erk signaling were involved. Furthermore, the 3- to 19-fold activation of the Erks in the presence of LY294002 suggested a down-regulation of the MEK/Erk cascade by PI-3'K signaling. Finally, the effect of IGF-I on DNA replication was almost completely abolished in clones of H4II cells expressing a dominant-negative form of Akt but was unaltered by rapamycin treatment of wild-type H4II cells. Altogether, these data support the notion that the stimulation of H4II rat hepatoma cell proliferation by IGF-I is especially dependent on Akt activation but independent on the Akt/mTOR signaling.

Identification of a unique gene expression signature that differentiates hepatocellular adenoma from well-differentiated hepatocellular carcinoma

It is often difficult to distinguish hepatocellular adenoma (HCA) from well-differentiated hepatocellular carcinoma (WDHCC) when limited tissue from a needle biopsy is evaluated. The aim of this study was to identify gene expression patterns that can distinguish HCA from WDHCC, with the ultimate goal of discovering novel diagnostic markers. Gene expression profile analysis was performed using Affymetrix U133Plus2 GeneChip microarrays on RNA isolated from frozen tissue of 6 HCA and 8 WDHCC specimens. Statistical analysis of microarray data identified 63 genes whose expression levels were significantly different between HCA and WDHCC. These included 57 genes overexpressed by HCA and 6 overexpressed by WDHCC. Eight genes were chosen for further analysis by quantitative RT-PCR on RNA derived from archived, paraffin-embedded tissue blocks of an independent validation set comprising 9 HCAs and 9 HCCs. Seven of the 8 genes demonstrated average expression differences between HCA and HCC that were concordant with the microarray findings, and their expression pattern correctly classified the 18 tumors into HCA and HCC using unsupervised clustering analysis. Furthermore, immunohistochemical staining performed on a third, independent set of 27 HCAs and 33 HCCs confirmed the expression differences at protein levels for 5 of the genes. Taken together, our data demonstrate significant molecular differences between HCA and WDHCC, despite their morphologic similarity. More importantly, we have identified a unique set of genes whose expression pattern can discriminate between these two types of hepatocellular neoplasms, suggesting the possibility of future development of ancillary molecular and immunohistochemical diagnostic methods.

Role of constitutively activated and insulin-like growth factor-stimulated ERK1/2 signaling in human hepatoma cell proliferation and apoptosis: evidence for heterogeneity of tumor cell lines

Enhanced insulin-like growth factor II (IGF-II) and type I IGF receptor (IGF-IR) gene expression in liver tumors and the development of liver tumors in transgenic mice overexpressing IGF-II in the liver suggest that the IGFs and underlying signaling cascades may play auto/paracrine roles in the control of hepatocarcinoma (HCC) cell proliferation and in their protection against apoptosis. We have focused on the role of mitogen-activated protein kinase (ERK1/2) signaling on human HepG2 and Huh-7 hepatoma cell proliferation and on the protection of these cells against drug-induced apoptosis. Physiological concentrations of IGF-I stimulated DNA replication in HepG2 cells (1.5-fold) but not in Huh-7 cells, and this effect was abolished by PD98059 (MEK-1 inhibitor). Doxorubicin or cisplatin treatment induced apoptosis (caspase-dependent poly[ADP-ribose]polymerase cleavage) in both cell lines, but dose-dependent reversion of drug-induced apoptosis (57-84%) by IGF-I was only observed in HepG2 cells. The very low level of IGF-IR at the plasma membrane of Huh-7 cells may account for their unresponsiveness to IGF-I. We have shown that drug treatment enhanced (17-fold) or did not modify constitutive ERK1/2 activity in cultured HepG2 or Huh-7 cells, respectively. In both cell lines, inhibition of constitutive and drug-induced ERK1/2 activity by PD98059 yielded a complete inhibition of drug-induced apoptosis. Altogether, our data demonstrate the heterogeneous response of human hepatoma cells to an IGF stimulus and suggest (1) that auto/paracrine effects of IGF-I/-II might contribute to the proliferation of HCC cells and to their protection against apoptosis in vivo and (2) that drug-induced activation of ERK1/2 plays a role in drug-induced apoptosis in human hepatoma cells.

Viral hepatitis and hepatocellular carcinoma

BACKGROUND

Hepatocellular carcinoma (HCC) is one of the most common malignant tumors in the world. The incidence of HCC varies considerably with the geographic area because of differences in the major causative factors. Chronic hepatitis B and C, mostly in the cirrhotic stage, are responsible for the great majority of cases of HCC worldwide. The geographic areas at the highest risk are South-East Asia and sub-Saharan Africa, here hepatitis B is highly endemic and is the main cause of HCC. In areas with an intermediate rate of HCC such as Southern Europe and Japan, hepatitis C is the predominant cause, whereas in low rate areas such as Northern Europe and the USA, HCC is often related to other factors as alcoholic liver disease. There is a rising incidence in HCC in developed countries during the last two decades, due to the increasing rate of hepatitis C infection and improvement of the clinical management of cirrhosis.

METHODS

This article reviews the literature on hepatitis and hepatocellular carcinoma. The Medline search was carried out using these key words and articles were selected on epidemiology, risk factors, screening, and prevention of hepatocellular carcinoma.

RESULTS

Screening of patients with advanced chronic hepatitis B and C with hepatic ultrasound and determination of serum alfa-fetoprotein may improve the detection of HCC, but further studies are needed whether screening improves clinical outcome. Hepatitis B and C viruses (HBV/HCV) can be implicated in the development of HCC in an indirect way, through induction of chronic inflammation, or directly by means of viral proteins or, in the case of HBV, by creation of mutations by integration into the genome of the hepatocyte.

CONCLUSION

The most effective tool to prevent HCC is avoidance of the risk factors such as viral infection. For HBV, a very effective vaccine is available. Preliminary data from Taiwan indicate a protective effect of universal vaccination on the development of HCC. Vaccination against HBV should therefore be a health priority. In patients with chronic hepatitis B or C, interferon-alfa treatment in a noncirrhotic stage is protective for HCC development in responders, probably by prevention of cirrhosis development. When cirrhosis is already present, the protective effect is less clear. For cirrhosis due to hepatitis B, a protective effect was demonstrated in Oriental, but not in European patients. For cirrhosis due to hepatitis C, interferon-alfa treatment showed to be protective in some studies, especially in Japan with a high incidence of HCC in untreated patients. Virological, but also merely biochemical response, seems to be associated with a lower risk of development of HCC. As most studies are not randomized controlled trials, no definitive conclusions on the long-term effects of interferon-alfa in HBV or HCV cirrhosis can be established. Especially in hepatitis C, prospective studies should be performed using the more potent reference treatments for cirrhotics, namely the combination of peginterferon and ribavirin.

An evaluation of the role of insulin-like growth factors (IGF) and of type-I IGF receptor signalling in hepatocarcinogenesis and in the resistance of hepatocarcinoma cells against drug-induced apoptosis

Strong evidence emphasizes the role of the insulin-like growth factor (IGF) system and of type-I IGF receptor (IGF-IR) signalling in tumourigenesis. In this connection: (i) changes in the expression pattern of components of the IGF system (autocrine/paracrine expression of IGF-I and -II, overexpression of IGF-IR, decreased expression of IGF-binding proteins (IGFBPs) and of type-II IGF receptor/cation-independent mannose-6-phosphate receptor (IGF-II/M6PR) and (ii) increased serum concentrations of proteases that cleave the IGFBPs (e.g., cathepsin D) were observed in patients with hepatocellular carcinomas (HCC), in human hepatoma cell lines and in their conditioned culture medium, as well as in rodent models of hepatocarcinogenesis. Accordingly, studies carried out with animal models do suggest that the IGF system and IGF-IR signalling may play a role in hepatocarcinogenesis and in deregulated proliferation and apoptosis of HCC cells. Finally the instrumental role of Raf/MEK/ERK, one of the signalling cascades stimulated by IGF-IR, in anthracycline-induced apoptosis of HepG2 and Huh-7 human hepatoma cell lines emphasizes that care must be taken when designing combinations of antitumoural molecules for antineoplastic treatment. This review addresses the putative roles of the IGF system in primary HCC, with a special focus on the underlying molecular mechanisms. In a second part it emphasizes the putative interference of IGF-IR signalling with chemotherapeutic drug-induced apoptosis in human hepatoma cells.

Loss of parental-specific methylation at the IGF2 locus in human hepatocellular carcinoma

Significant production of the growth factor IGF2 has been reported in human hepatocellular carcinomas (HCCs). Disturbances associated with changes in methylation at this locus or affecting the 11p15.5 imprinting domain as a whole can be postulated in HCCs. In the present study, the methylation status of differentially methylated regions of the imprinted genes TSSC5, LIT1, and IGF2, which span the 11p15 domain, was analysed in 71 liver tissues from virus-associated and non-virus-associated HCCs compared with six normal liver tissues. Altered methylation of TSSC5 and LIT1 was observed in only 6% and 8% of HCCs, respectively, compared with 89% at the IGF2 locus, suggesting that these loci were not concomitantly dysregulated. These observations suggest that loss of parental-specific methylation at the IGF2 locus may be specifically associated with HCC, whether virus-associated or non-virus-associated, and arising in cirrhotic or non-cirrhotic livers.

Increased IGF-I : IGFBP-3 ratio in patients with hepatocellular carcinoma

BACKGROUND

The development of hepatocellular carcinoma in liver cirrhosis is associated with altered synthesis and secretion of several growth factors.

AIM

The aim of this prospective study was to investigate the potential implication of IGF-I and its major binding protein (IGFBP-3) in the development of hepatocellular carcinoma.

PATIENTS AND METHODS

IGF-I and IGFBP-3 were measured in 150 healthy subjects, 40 patients with liver cirrhosis and 63 with liver cirrhosis and untreated hepatocellular carcinoma. The ratio between IGF-I and IGFBP-3 was also calculated.

RESULTS

Serum IGF-I (70 +/- 10 and 65 +/- 7 vs. 185 +/- 6.4 microg/l, P < 0.001) and IGFBP-3 levels (1225 +/- 113 and 984 +/- 67 vs. 3017 +/ -80 microg/l, P < 0.001) were lower in patients with liver cirrhosis, without or with hepatocellular carcinoma, than in controls. Age was negatively correlated with IGF-I levels in patients with liver cirrhosis (r = -0.6; P = 0.0002) as well as in controls (r = -0.8, P < 0.0001), but not in patients with hepatocellular carcinoma (r = -0.2; P = 0.2). Additionally, in patients with liver cirrhosis (r = -0.54; P = 0.0003) and more weakly in those with hepatocellular carcinoma (r = -0.24; P = 0.04) IGF-I levels were negatively correlated with liver failure measured according with Child class. Despite patients with class C hepatocellular carcinoma being older than those in the same functional class with cirrhosis (64 +/- 2 vs. 57 +/- 12 years, P < 0.01), they had a significantly increased IGF-I : IGFBP-3 ratio (0.18 +/- 0.05 vs. 0.41 +/- 0.09, P = 0.04), due mostly to increased IGF-I levels (27.1 +/- 5.6 vs. 42 +/- 6.2 microg/l) as IGFBP-3 levels were similar to patients with cirrhosis (734 +/- 81 vs. 679 +/- 83 microg/l).

CONCLUSIONS

Hepatocellular carcinoma is associated with a higher IGF-I : IGFBP-3 ratio than that found in patients with liver cirrhosis and a similar degree of liver failure.

Focal overexpression of insulin-like growth factor 2 by hepatocytes and cholangiocytes in viral liver cirrhosis

Insulin-like growth factor (IGF)-2 is overexpressed in hepatocellular carcinoma and accompanying dysplastic lesions. IGF-2 signalling is mediated through IGF-1 receptor (IGF-1R), while mannose 6-phosphate/insulin-like growth factor-2 receptor (M6P/IGF-2R) controls pericellular levels of free IGF-2. We studied, by in situ hybridisation and immunohistology, 18 liver specimens with cirrhosis of different aetiology without neoplastic or dysplastic lesions. Immunohistology was also performed for insulin receptor IGF-1R and IGF-binding proteins 3 and 4. High focal levels of IGF-2 RNA were found in some hepatocytes of all livers with HBV- or HCV-induced cirrhosis (n=10), but in only one of the cirrhoses with nonviral aetiology (n=8). IGF-2 was overexpressed in biliary duct epithelial cells in one case. Compared with noncirrhotic liver, all cirrhotic specimens showed reduced hepatocellular expression of M6P/IGF-2R protein, which contrasted with enhanced expression in perisinusoidal cells. Immunostaining for the other antigens did not reveal significant differences. Upregulation of IGF-2 in some hepatocytes may lead to high focal IGF-2 levels sufficient to saturate local IGF-2 binding capacities, and may result in an increased susceptibility to cellular dedifferentiation and, ultimately, liver cancer. Downregulation of hepatocellular M6P/IGF-2R and upregulation of IGF-2 seem to be early events in hepatocarcinogenesis prior to the appearance of morphologically distinct dysplastic lesions. Elevated focal IGF-2 transcript levels may therefore indicate an increased risk for hepatocellular and cholangiocellular carcinomas.

Serum insulin-like growth factor I evaluation as a useful tool for predicting the risk of developing hepatocellular carcinoma in patients with hepatitis C virus-related cirrhosis: a prospective study

BACKGROUND

Although experimental studies have demonstrated an important role of insulin-like growth factor I (IGF-I) in hepatocarcinogenesis, the clinical data about IGF-I in patients with hepatocellular carcinoma (HCC) are scarce and controversial. To the authors' knowledge, this is the first prospective study investigating the longitudinal correlation between modifications in serum IGF-I levels and the development of HCC in a cohort of patients with hepatitis C virus (HCV)-related cirrhosis.

METHODS

One hundred fourteen consecutive patients with HCV-related Child Grade A cirrhosis were followed prospectively at the Second University of Naples for 56.4 +/- 12.0 months with ultrasound examinations of the liver and serum alpha-fetoprotein determination every 6 months. At each clinical evaluation, the severity of disease was graded according to the established Child-Pugh scoring system. Serum IGF-I levels were measured prospectively at the study entry and at least every 12 months throughout follow-up.

RESULTS

Twenty patients (19.2%) developed HCC during follow-up. Eleven of these patients had persistent Child Grade A cirrhosis for the whole study, whereas the other 9 patients developed HCC after their cirrhosis progressed from Child Grade A to Grade B. In patients who remained free of HCC for the whole study, serum IGF-I concentrations did not modify significantly during follow-up. Conversely, in patients who developed HCC, IGF-I levels decreased significantly during follow-up (from 72.6 +/- 29.9 microg/L to 33.8 +/- 14.5 microg/L; P = 0.001). In these patients, the significant decrease occurred both in patients with persistent Child Grade A cirrhosis and in patients with cirrhosis that progressed from Child Grade A to Grade B. The reduction in IGF-I level preceded the diagnosis of HCC by 9.3 +/- 3.1 months.

CONCLUSIONS

This prospective study demonstrates that, in patients with HCV-related cirrhosis, 1) the development of HCC is accompanied by a significant reduction of serum IGF-I levels independent of the grade of impairment of liver function; and 2) modification of the IGF-I level precedes the morphologic appearance of HCC, permitting a precocious diagnosis of the tumor.

Up-regulation of heparin binding epidermal growth factor-like growth factor and amphiregulin expression in Helicobacter pylori-infected human gastric mucosa

BACKGROUND

Host response plays a major role in pathogenesis of Helicobacter pylori-induced gastroduodenal disease including adenocarcinoma of distal stomach. Epidermal growth factor-related growth factors are important modulators of gastric homeostasis in normal and damaged gastrointestinal mucosa.

AIM

To evaluate expression of heparin binding epidermal growth factor and amphiregulin in antral mucosa of Helicobacter pylori-infected and non-infected dyspeptic patients and to correlate levels of heparin binding-epidermal growth factor and amphiregulin mRNA with mitogenic activity of gastric epithelial cells.

METHODS

A total of 10 Helicobacter pylori-infected and 15 Helicobacter pylori non-infected (10 with and 5 without gastritis) dyspeptic patients were studied. Diagnosis of Helicobacter pylori infection was based on rapid urease test and histology. Heparin binding-epidermal growth factor and amphiregulin mRNA expression in antral mucosa were assessed by reverse transcriptase-polymerase chain reaction. Protein expression and localization of both peptides were determined by immunohistochemistry. Mitogenic activity of antral gastric mucosa was assessed by determination of proliferating cell nuclear antigen labelling index by immunohistochemistry.

RESULTS

Heparin binding-epidermal growth factor and amphiregulin mRNA expression increased in Helicobacter pylori-infected vs Helicobacter pylori non-infected patients. Heparin binding-epidermal growth factor and amphiregulin immunostaining was more intense and deeper in gastric gland compartment in infected mucosa than in non-infected mucosa. Increase in heparin binding-epidermal growth factor and amphiregulin mRNA expression significantly correlated with increase in proliferating cell nuclear antigen labelling index.

CONCLUSIONS

Helicobacter pylori gastritis is associated with up-regulation of heparin binding-epidermal growth factor and amphiregulin which correlates with increased mitogenic activity of gastric mucosa. Increased heparin binding-epidermal growth factor and amphiregulin expression is postulated to contribute to reparative response of gastric mucosa to Helicobacter pylori infection.

IGF-1 in gynaecology and obstetrics: update 2002

Recent discoveries on endocrine, paracrine and autocrine involvement of insulin-like growth factor-1 (IGF-1) in the proliferation of many tissues raised the attention of its role in reproduction and in the growth of various cancers as well as of benign proliferations. The intention of this article is to focus on IGF-1 in the field of gynaecology. Perimenopausal women who exhibit high IGF-1 and low IGF binding protein (IGFBP) levels, like IGFBG-3, have an increased risk of developing breast cancer. A higher risk for cervical, ovarian and endometrial cancer is related to high IGF-1 levels in post- and premenopausal women. It has been shown that myomas, by far the most common benign uterine tumor in women, grow in the presence of IGF-1, in vitro as well as in vivo. Studies show that IGF-1 is involved in the differentiation of various reproductive tissues, like endometrium and ovarian tissues. Patients suffering from polycystic ovary syndrome (PCO) frequently show insulin resistance accompanied by an increase of IGF-1 in plasma. Plasma IGF-1 levels are higher in cases of severe endometriosis, however, in endometriosis and in PCO IGF levels locally in the endometrium are reduced, what might explain infertility. Recently, it was shown that IGF facilitates the implantation of the human embryo in the endometrium during IVF. Implantation is a paradox where different immune systems have to collaborate to make implantation and survival of the pregnancy possible. IGF seems to be the starter molecule so that the two epithelia can fuse. A disturbance can result in complications during pregnancy i.e. spontaneous miscarriage, preeclampsia as well as defects of the embryo. Therefore, IGF is a useful marker in successful pregnancy as well. A better mechanistic understanding of IGF-1 action on the cellular level not only provides more elegant mechanistic explanations for the scientist, but the practitioner might find it interesting to utilize its diagnostic potential as a marker for various diseases. The relation between systemic IGF levels and local tissue IGF-1 levels has not yet been determined for all conditions.

Aberrant expression of fetal RNA-binding protein p62 in liver cancer and liver cirrhosis

p62 is a RNA-binding protein that was isolated by immunoscreening a cDNA expression library with autoantibodies from patients with hepatocellular carcinoma (HCC). This autoantigen binds to mRNA encoding insulin-like growth factor II, which has been found to be overexpressed in HCC and is tumorigenic in transgenic animals. Immunohistochemical analysis of HCC liver showed that 33% (9 of 27) exhibited readily detectable staining of p62 protein in the cytoplasm of all malignant cells in cancer nodules, whereas it was undetectable in adjacent nonmalignant liver cells. In addition one of two patients with cholangiocarcinoma expressed p62 in malignant bile duct epithelial cells. p62 expression was also detected in scattered cells in cirrhotic nodules in contrast to uniform expression in all cells in HCC nodules. In HCC nodules, p62 mRNA was also detected by reverse transcriptase-polymerase chain reaction analysis. Nine normal adult livers did not contain detectable p62 mRNA or p62 protein whereas five fetal livers were all positive for mRNA and protein. The observations show that p62 is developmentally regulated, expressed in fetal, but not in adult liver, and aberrantly expressed in HCC and could be playing a role in abnormal cell proliferation in HCC and cirrhosis by modulating expression of growth factors such as insulin-like growth factor II.

The IGF axis and hepatocarcinogenesis

Deregulation of the insulin-like growth factor (IGF) axis, including the autocrine production of IGFs, IGF binding proteins (IGFBPs), IGFBP proteases, and the expression of the IGF receptors, has been identified in the development of hepatocellular carcinoma (HCC). Characteristic alterations detected in HCC and hepatoma cell lines comprise the increased expression of IGF-II and the IGF-I receptor (IGF-IR), which have emerged as crucial events in malignant transformation and the growth of tumours. Alterations of IGFBP production and the proteolytic degradation of IGFBPs resulting in an excess of bioactive IGFs, as well as the defective function of the IGF degrading IGF-II/mannose 6-phosphate receptor (IGF-II/M6PR), may further potentiate the mitogenic effects of IGFs in the development of HCC.

Preliminary results of interferon-alpha therapy on woodchuck hepatitis virus-induced hepatocarcinogenesis: possible benefit in female transgenic mice

BACKGROUND

C-myc activation is a potent oncogenic event in hepatocarcinogenesis. The aim of this study was to test the preventive effect of interferon-alpha (IFN-alpha) on the development of dysplasia and subsequent hepatocellular carcinoma (HCC) in transgenic (Tg) mice overexpressing c-myc in the liver.

METHODS

The WHV/c-myc Tg mice recapitulating woodchuck hepatitis virus-induced hepatocarcinogenesis were treated with IFN-alpha, starting early in life until sacrifice at pre-neoplastic or neoplastic stages. Transgene expression was assessed by reverse transcription-polymerase chain reaction (RT-PCR), hepatocyte proliferation was assessed by bromodeoxyuridine incorporation and RT-PCR for proliferating cell nuclear antigen, and apoptosis was assessed by in situ nick-end-labeling of DNA.

RESULTS

C-myc expression and hepatocyte proliferation were significantly reduced in treated female mice, without modification of apoptosis, correlating with a lower severity of dysplasia in 9/12 treated animals at pre-neoplastic stages. At the neoplastic stage, 2/3 treated females neither exhibited carcinoma nor dysplasia, while all 6/6 untreated mice and 3/3 treated males developed carcinomas.

CONCLUSIONS

Inhibition of c-myc and hepatocyte proliferation by long-term administration of IFN-alpha was associated with a decrease, or a delay, of oncogenesis in the mouse Tg HCC model. Whether c-myc and hepatocyte proliferation down-regulation could be relevant parameters of IFN-alpha efficiency for hepatocarcinogenesis prevention in cirrhotic patients should be established.

Pathogenesis of hepatocellular carcinoma

The pathogenesis of HCC is poorly understood at present. There is insufficient understanding to propose a robust general model of hepatic carcinogenesis, partly because pathogenic host and environmental factors show significant regional variation, making such generalization difficult. Figure 4 is a model based on data presented in this article. Multiple risk factors for HCC have been identified, including cirrhosis, male gender, increasing patient age, toxins, chronic viral hepatitis, and other specific liver diseases. The understanding of how the individual risk factors result in genetic changes is rudimentary, and there is even less understanding about interactions between risk factors. Future studies should acknowledge the geographic origin of the HCCs studied and consider the effects of cirrhosis, gender, and age. A more rigorous approach to these factors may help explicate the interaction with specific liver diseases so that a comprehensive model of hepatic carcinogenesis can be developed.

Insulin and IGF-1 stimulate the beta-catenin pathway through two signalling cascades involving GSK-3beta inhibition and Ras activation

We examined the interplay between the insulin/IGF-1- and beta-catenin-regulated pathways, both of which are suspected to play a role in hepatocarcinogenesis. Insulin and IGF-1 stimulated the transcription of a Lef/Tcf-dependent luciferase reporter gene by 3-4-fold in HepG2 cells. This stimulation was mediated through the activation of phosphatidylinositol 3-kinase (PI 3-K)/Akt and the inhibition of glycogen synthase kinase-3beta (GSK-3beta) since the effects of insulin and IGF-1 were inhibited by dominant-negative mutants of PI 3-K or Akt and an uninhibitable GSK-3beta. Together with inhibiting GSK-3beta, insulin and IGF-1 increased the cytoplasmic levels of beta-catenin. The PI 3-K/Akt/GSK-3beta pathway was not the sole to mediate insulin and IGF-1 stimulation of Lef/Tcf-dependent transcription. The Ras signalling pathway was also required as (i) the stimulatory effects of insulin and IGF-1 were inhibited by dominant-negative Ras or the MEK1 inhibitor PD98059 and (ii) activated Ha-Ras or constitutively active MEK1 synergized with catalytically inactive GSK-3beta to stimulate Lef/Tcf-dependent transcription. This study provides the first evidence that insulin and IGF-1 stimulate the beta-catenin pathway through two signalling cascades bifurcating downstream of PI 3-K and involving GSK-3beta inhibition and Ras activation. These findings demonstrate for the first time the ability of insulin and IGF-1 to activate the beta-catenin pathway in hepatoma cells and thereby provide new insights into the role of these factors in hepatocarcinogenesis.

The H19 endodermal enhancer is required for Igf2 activation and tumor formation in experimental liver carcinogenesis

The expression of the linked but reciprocally imprinted Igf2 and H19 genes is activated in adult liver in the course of tumor development. By in situ hybridization analysis we have shown that both the Igf2 and H19 RNAs are expressed in the majority of the neoplastic nodules, and that hepatocellular carcinomas are developed in an experimental model of liver carcinogenesis. H19 is also highly activated in smaller and less distinct hyperplastic regions. The few neoplastic areas showing Igf2 but no H19 RNA display loss of the maternally inherited allele at the Igf2/H19 locus. These data are compatible with the existence of a common activation mechanism of these two genes during liver carcinogenesis and with a stronger H19 induction in the pre-neoplastic lesions. By using mice carrying a deletion of the H19 endodermal enhancer, we show that this regulatory element is necessary for the activation of the Igf2 and H19 genes upon induction of liver carcinogenesis. Furthermore, multiple sites of the H19 endodermal enhancer region become hypersensitive to DNase I when the carcinogenesis process is induced. Lastly, liver tumors developed in mice paternally inheriting the H19 enhancer deletion are found to have marked growth delays, increased frequency of apoptotic nuclei, and lack of Igf2 mRNA expression, thus indicating that this regulatory element plays a major role in the progression of liver carcinogenesis, since it is required for the activation of the anti-apoptotic Igf2 gene.

Expression of transforming growth factor beta-1 in chronic hepatitis and hepatocellular carcinoma associated with hepatitis C virus infection

BACKGROUND

Transforming growth factor beta-1 (TGF beta 1) has been suggested to play a role in the development, growth or progression of hepatocellular carcinoma (HCC). Genotype and serum titer of HCV also affect the occurrence of HCC in chronic hepatitis C. In this study, we were to evaluate the effects of genotype or serum titer of HCV on the expression of TGF beta 1. We also intended to examine the correlation between the up-regulation of TGF beta 1 and the association with HCC in patients with chronic hepatitis C.

METHODS

We studied 19 patients with chronic hepatitis C and 18 with HCC associated with HCV infection. HCV genotype was determined by line probe reverse hybridization assay and the amount of HCV-RNA was quantitated by branched DNA signal amplification assay. Serum TGF beta 1 level was measured by enzyme linked immunosorbent assay.

RESULTS

HCV genotypes of patients with HCC were similar to those without it. Serum HCV-RNA titer was higher in genotype 1b than in non-1b (p < 0.05). Serum TGF beta 1 levels were higher in HCC than in chronic hepatitis (p < 0.05). However, there was no significant difference in the serum TGF beta 1 level between genotype 1b and non-1b. Also, it was not correlated with the serum HCV-RNA titer or alanine aminotransferase levels.

CONCLUSION

TGF beta 1 seems to be overexpressed in HCC compared to that of chronic hepatitis C: it was not affected by serum ALT levels, genotype or serum HCV titer. It is suggested that TGF beta 1 may be associated with the malignant transformation of hepatocyte or the progression of HCV-associated HCC.

IGF-II/IGF-I receptor pathway up-regulates COX-2 mRNA expression and PGE2 synthesis in Caco-2 human colon carcinoma cells

Nonsteroidal anti-inflammatory drugs reduce the risk of colon cancer and this effect is mediated in part through inhibition of type 2 prostaglandin endoperoxide synthase/ cyclo-oxygenase (COX-2). In the present study, we demonstrate that COX-2 expression and PGE2 synthesis are up-regulated by an IGF-II/IGF-I receptor autocrine pathway in Caco-2 colon carcinoma cells. COX-2 mRNA and PGE2 levels are higher in proliferating cells compared with post-confluent differentiated cells and in cells that constitutively overexpress IGF-II. Up-regulation of COX-2 expression by IGF-II is mediated through activation of IGF-I receptor because: (i) treatment of Caco-2 cells with a blocking antibody to the IGF-I receptor inhibits COX-2 mRNA expression; (ii) transfection of Caco-2 cells with a dominant negative IGF-I receptor reduces COX-2 expression and activity. Also, the blockade of the PI3-kinase, that mediates the proliferative effect of IGF-I receptor in Caco-2 cells, inhibits IGF-II-dependent COX-2 up-regulation and PGE2 synthesis. Moreover, COX-2 expression and activity inversely correlate with the increase of apoptosis in parental, IGF-II and dominant-negative IGF-I receptor transfected cells. This study suggests that induction of proliferation and tumor progression of colon cancer cells by the IGF-II/IGF-I receptor pathway may depend on the activation of COX-2-related events.

Insulin-like growth factor 1 in hepatocellular carcinoma and metastatic liver cancer in men

The insulin-like growth factor (IGF) axis has important autocrine, paracrine, and endocrine roles in the promotion of growth. Alterations of the IGF system have recently been implicated in the pathogenesis of several malignancies, but the relation to hepatocellular carcinoma (HCC) risk is unclear. To address this issue, we used an immunoradiometric assay to quantify IGF-1 levels in serum samples in a hospital-based, case-control study in Greece. The study subjects were all men and included 53 patients with HCC positive for hepatitis B and/or hepatitis C virus infections, 20 virus-negative HCC patients, 25 virus-negative patients with metastatic liver cancer (MLC), and 111 virus-negative control subjects. Data were analyzed by multiple linear regression, using IGF-1 as the dependent variable. The mean value of IGF-1 was 65.9 ng/ml among virus-positive HCC patients, 79.5 ng/ml among virus-negative HCC patients, 110.8 ng/ml among patients with MLC, and 174.7 ng/ml among hospital controls. After controlling for the degree of liver damage, as assessed by prothrombin time and serum albumin level, the reduction in IGF-1 level among HCC patients was found to be more than could be attributed to liver damage alone. This finding may have both diagnostic and pathophysiological implications.

Applications of developmental biology to medicine and animal agriculture

With the complete sequence of the human genome expected by winter 2001, genomic-based drug discovery efforts of the pharmaceutical industry are focusing on finding the relatively few therapeutically useful genes from among the total gene set. Methods to rapidly elucidate gene function will have increasing value in these investigations. The use of model organisms in functional genomics has begun to be recognized and exploited and is one example of the emerging use of the tools of developmental biology in recent drug discovery efforts. The use of protein products expressed during embryo-genesis and the use of certain pluripotent cell populations (stem cells) as candidate therapeutics are other applications of developmental biology to the treatment of human diseases. These agents may be used to repair damaged or diseased tissues by inducing or directing developmental programs that recapitulate embryonic processes to replace specialized cells. The activation or silencing of embryonic genes in the disease state, particularly those encoding transcription factors, is another avenue of exploitation. Finally, the direct drug-induced manipulation of embryonic development is a unique application of developmental biology in animal agriculture.

Insulin-like growth factor 1 in hepatocellular carcinoma and metastatic liver cancer in men

The insulin-like growth factor (IGF) axis has important autocrine, paracrine, and endocrine roles in the promotion of growth. Alterations of the IGF system have recently been implicated in the pathogenesis of several malignancies, but the relation to hepatocellular carcinoma (HCC) risk is unclear. To address this issue, we used an immunoradiometric assay to quantify IGF-1 levels in serum samples in a hospital-based, case-control study in Greece. The study subjects were all men and included 53 patients with HCC positive for hepatitis B and/or hepatitis C virus infections, 20 virus-negative HCC patients, 25 virus-negative patients with metastatic liver cancer (MLC), and 111 virus-negative control subjects. Data were analyzed by multiple linear regression, using IGF-1 as the dependent variable. The mean value of IGF-1 was 65.9 ng/ml among virus-positive HCC patients, 79.5 ng/ml among virus-negative HCC patients, 110.8 ng/ml among patients with MLC, and 174.7 ng/ml among hospital controls. After controlling for the degree of liver damage, as assessed by prothrombin time and serum albumin level, the reduction in IGF-1 level among HCC patients was found to be more than could be attributed to liver damage alone. This finding may have both diagnostic and pathophysiological implications.

Allelic imbalance of insulin-like growth factor II gene expression in cancerous and precancerous lesions of the liver

Allelic imbalance of the insulin-like growth factor II (IGF II) gene expression is often seen in hepatocellular carcinoma (HCC). To investigate the role of allelic imbalance in hepatocarcinogenesis, we have studied allelic expression status of the IGF II gene in dysplastic nodules, which are precancerous lesions of HCC, as well as in HCCs of different histological grade, and the influence of the allelic imbalance on IGF II gene expression has also been examined. Allelic imbalance was observed in 3 of 7 dysplastic nodules, in 7 of 9 well-differentiated HCCs, and in 8 of 9 moderately differentiated HCCs. IGF II gene expression level, which was studied by a semiquantitative reverse-transcriptase polymerase chain reaction (RT-PCR), was significantly higher (3.6-fold) in the dysplastic nodules than the control livers, but a significant increase in the IGF II gene expression was not observed in well- and moderately differentiated HCCs as compared with the control livers. These results demonstrate that the allelic imbalance of the IGF II gene expression is seen in the early stage (precancerous lesions) of hepatocarcinogenesis. Association of the allelic imbalance with an increased expression of the IGF II gene in the precancerous lesions might suggest a possible involvement of an IGF II autocrine loop in the pathogenesis of these lesions.

Co-localisation of insulin-like growth factor II and the proliferation marker MIB1 in hepatocellular carcinoma cells

AIM

To assess the effect of insulin-like growth factor II (IGF-II) on proliferation of hepatocellular carcinoma (HCC) cells.

METHODS

Expression of IGF-II mRNA and protein was detected in 10 archival HCC specimens using in situ hybridisation and immunohistochemistry, respectively. Expression of the Ki-67 antigen, a proliferation marker, was determined immunohistochemically on the same sections.

RESULTS

Increased expression of IGF-II mRNA and protein was detected in five of the 10 HCCs in cells located at the periphery of tumour nests. The pattern of localisation of IGF-II was almost identical with that of Ki-67 antigen.

CONCLUSIONS

Most of the Ki-67 antigen positive cells co-expressed IGF-II, suggesting that IGF-II may act as an autocrine or paracrine growth factor, and may play an important role in the development of HCC.