Expression of insulin-like growth factor II mRNA in hepatocellular carcinoma

Differential expression of insulin-like growth factor type 1 receptor identifies heterogeneous intrahepatic regulatory T subsets in mouse hepatocellular carcinoma

Understanding regulatory T-cell (Treg)-mediated tumor tolerance is critical for designing immunotherapy against hepatocellular carcinoma (HCC). In this study, we characterized the expression of insulin-like growth factor type 1 receptor (IGF1R) in intrahepatic Tregs in a chemical-induced mouse HCC model. We found two intrahepatic Treg subsets with differential IGF1R expression: IGF1Rhi Tregs and IGF1Rlo/- Tregs. Functional assays indicated that compared with IGF1Rlo/- Tregs, IGF1Rhi Tregs produced more TGF-β and IL-10 and were more proliferative in vivo. Furthermore, IGF1Rhi Tregs exhibited higher phosphorylation of the mammalian target of the rapamycin complex 1 (mTORC1) in vivo. However, in vitro stimulation and immunosuppression assay revealed that the immunosuppressive capacity of the two Treg subsets was equivalent, as evidenced by comparable cytokine production and immunosuppressive effect over conventional T cells. The transcriptome sequencing analysis revealed up-regulation of genes that encode proteins essential for glycolysis, oxidative phosphorylation, and electron transport chain in IGF1Rhi Tregs. Consistently, IGF1Rhi Tregs produces more adenosine triphosphate (ATP), lactate, and reactive oxygen species (ROS). Furthermore, malignant cells in the tumor nodules induced IGF1R down-regulation in Tregs at the mRNA level. In summary, we identified the heterogeneity of intrahepatic Tregs in HCC which might play significant roles in tumor immunity.

Insulin-like growth factor (IGF) axis in cancerogenesis

Determination of the role of insulin-like growth factor (IGF) family components in carcinogenesis of several human tumors is based on numerous epidemiological and pre-clinical studies, experiments in vivo and in vitro and on attempts at application of drugs affecting the IGF axis. Investigative hypotheses in original studies were based on biological functions manifested by the entire family of IGF (ligands, receptors, linking proteins, adaptor molecules). In the context of carcinogenesis the most important functions of IGF family involve intensification of proliferation and inhibition of cell apoptosis and effect on cell transformation through synthesis of several regulatory proteins. IGF axis controls survival and influences on metastases of cells. Interactions of IGF axis components may be of a direct or indirect nature. The direct effects are linked to activation of PI3K/Akt signaling pathway, in which the initiating role is first of all played by IGF-1 and IGF-1R. Activity of this signaling pathway leads to an increased mitogenesis, cell cycle progression, and protection against different apoptotic stresses. Indirect effects of the axis depend on interactions between IGF and other molecules important for cancer etiology (e.g. sex hormones, products of suppressor genes, viruses, and other GFs) and the style of life (nutrition, physical activity). From the clinical point of view, components of IGF system are first of all considered as diagnostic serous and/or tissue biomarkers of a given cancer, prognostic factors and attractive target of modern anti-tumor therapies. Several mechanisms in which IGF system components act in the process of carcinogenesis need to be clarified, mainly due to multifactorial etiology of the neoplasms. Pin-pointing of the role played in carcinogenesis by any single signaling pathway remains particularly difficult. The aim of this review is to summarize the current data of several epidemiological studies, experiments in vitro and on animal models, to increase our understanding of the complex role of IGF family components in the most common human cancers.

Predictive value of serum insulin-like growth factor-1 in hepatocellular carcinoma

BACKGROUND

Hepatocellular carcinoma (HCC) is the commonest primary malignant cancer of the liver in the world. Insulin-like growth factor-1 (IGF-1) levels reflect hepatic function and are inversely correlated with the severity of background chronic liver disease.

OBJECTIVE

This study evaluated whether basal serum IGF-1 levels can predict prognosis of HCC patients according to different risks of disease progression.

MATERIALS AND METHODS

A total of 89 patients with hepatocellular carcinoma (HCC) were recruited in 3 groups: Group I, 30 HCC patients receiving sorafinib; Group II, 30 HCC patients with best supportive care; and Group III include 29 patients undergoing transcatheter arterial chemoembolization (TACE). All patients were investigated for serum levels of AST, ALP, Bb, Cr, BUN, AFP and IGF-I.

RESULTS

Patients with disease control had significantly higher baseline IGF-1 levels 210 (185-232.5) ng/mL (p value<0.01) than did patients without disease control. Low basal IGF-1 levels were associated with advanced HCC, such as multiple tumors and advanced stage, and low IGF-1 levels predicted shorter TTP and overall survival in patients treated with TACE.

CONCLUSIONS

The levels of serum IGF-1, expressed as continuous values, may be helpful for accurately assessing hepatic function and the prognostic stratification of patients with HCC.

Hepatitis B virus X protein promotes P3 transcript expression of the insulin-like growth factor 2 gene via inducing hypomethylation of P3 promoter in hepatocellular carcinoma

BACKGROUND & AIMS

Hepatitis B virus (HBV) X protein (HBx) contributes to hepatocarcinogenesis. The overexpression of transcripts from P3 and P4 promoters of the insulin-like growth factor 2 (IGF2) gene is observed in hepatocellular carcinoma (HCC). Here, we aimed to explore the involvement of HBx in P3-driven mRNA overexpression and underlying epigenetic mechanism.

METHODS

P3 mRNA, P3 methylation status, HBx mRNA and HBx protein were analysed in human HCC samples with and without HBV infection using quantitative RT-PCR, bisulphite sequencing and Western blotting. The effects of HBx on P3 mRNA expression, and P3 transcriptional activity and methylation were further evaluated in HCC cell lines.

RESULTS

P3 mRNA level was higher and P3 methylation level was lower in HBV-positive HCC specimens compared with those of HBV-negative HCC specimens. P3 transcript abundance was positively correlated with HBx expression and negatively correlated with P3 methylation in HCC specimens. The stable expression of HBx upregulated P3 mRNA expression and reduced P3 methylation level in HepG2-HBx cells. The transient expression of HBx stimulated P3 promoter activity and decreased P3 methylation level of P3 promoter-luciferase construct in a dose-dependent manner in HepG2 and Huh-7 cells. Furthermore, HBx mRNA expression was found to be independent predictive factors for both shorter disease-free survival time and shorter overall survival time of HCC patients.

CONCLUSION

HBx may promote IGF2-P3 transcript expression by inducing hypomethylation of P3 promoter and may be associated with an inferior clinical outcome of HBV-related HCC patients. This study provides useful information for understanding the mechanism of HBx-mediated HCC.

Hepatocellular carcinoma biology

Hepatocellular carcinoma (HCC) is the most common primary hepatic malignancy. Its incidence and prevalence is globally heterogeneous with the highest rates in Southeast Asia and Sub-Saharan Africa. In Western Industry nations, its incidence has significantly increased throughout the previous three decades. Its global heterogeneity is in part a reflection of the global distribution of its risk factors. Its prognosis is dismal with a 5-year survival of 11 %. The only potentially curative treatment is surgical with either resection or orthotopic liver transplantation. However, the majority of HCC patients are diagnosed at an advanced stage at which surgical therapies are not feasible. HCC is considered chemotherapy-resistant-a characteristic thought to be mediated in part through stem-like tumor initiating cells (STICs). Recent studies have provided significant insights in the hepatocarcinogenesis and the molecular signaling pathways of this malignancy resulting in the development of novel, molecular targeted therapies with modest therapeutic benefit. Our growing understanding of the biology of this malignancy will help in the development of novel, molecular-targeted therapies.

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.

Development of IGF signaling antibody arrays for the identification of hepatocellular carcinoma biomarkers

Purpose

Our objective was to develop a system to simultaneously and quantitatively measure the expression levels of the insulin-like growth factor (IGF) family proteins in numerous samples and to apply this approach to profile the IGF family proteins levels in cancer and adjacent tissues from patients with hepatocellular carcinoma (HCC).

Experimental Design

Antibodies against ten IGF family proteins (IGF-1, IGF-1R, IGF-2, IGF-2R, IGFBP-1, IGFBP-2, IGFBP-3, IGFBP-4, IGFBP-6, and Insulin) were immobilized on the surface of a glass slide in an array format to create an IGF signaling antibody array. Tissue lysates prepared from patient's liver cancer tissues and adjacent tissues were then applied to the arrays. The proteins captured by antibodies on the arrays were then incubated with a cocktail of biotinylated detection antibodies and visualized with a fluorescence detection system. By comparison with standard protein amount, the exact protein concentrations in the samples can be determined. The expression levels of the ten IGF family proteins in 25 pairs of HCC and adjacent tissues were quantitatively measured using this novel antibody array technology. The differential expression levels between cancer tissues and adjacent tissues were statistically analyzed.

Results

A novel IGF signaling antibody array was developed which allows the researcher to simultaneously detect ten proteins involved in IGF signal pathway with high sensitivity and specificity. Using this approach, we found that the levels of IGF-2R and IGFBP-2 in HCC tissues were higher than those in adjacent tissues.

Conclusion

Our IGF signaling antibody array which can detect the expression of ten IGF family members with high sensitivity and specificity will undoubtedly prove a powerful tool for drug and biomarker discovery.

Targeting insulin-like growth factor axis in hepatocellular carcinoma

The insulin-like growth factor (IGF) axis contains ligands, receptors, substrates, and ligand binding proteins. The essential role of IGF axis in hepatocellular carcinoma (HCC) has been illustrated in HCC cell lines and in animal xenograft models. Preclinical evidence provides ample indication that all four components of IGF axis are crucial in the carcinogenic and metastatic potential of HCC. Several strategies targeting this system including monoclonal antibodies against the IGF 1 receptor (IGF-1R) and small molecule inhibitors of the tyrosine kinase function of IGF-1R are under active investigation. This review describes the most up-to-date understanding of this complex axis in HCC, and provides relevant information on clinical trials targeting the IGF axis in HCC with a focus on anti-IGF-1R approach. IGF axis is increasingly recognized as one of the most relevant pathways in HCC and agents targeting this axis can potentially play an important role in the treatment of HCC.

Targeting insulin-like growth factor axis in hepatocellular carcinoma

The insulin-like growth factor (IGF) axis contains ligands, receptors, substrates, and ligand binding proteins. The essential role of IGF axis in hepatocellular carcinoma (HCC) has been illustrated in HCC cell lines and in animal xenograft models. Preclinical evidence provides ample indication that all four components of IGF axis are crucial in the carcinogenic and metastatic potential of HCC. Several strategies targeting this system including monoclonal antibodies against the IGF 1 receptor (IGF-1R) and small molecule inhibitors of the tyrosine kinase function of IGF-1R are under active investigation. This review describes the most up-to-date understanding of this complex axis in HCC, and provides relevant information on clinical trials targeting the IGF axis in HCC with a focus on anti-IGF-1R approach. IGF axis is increasingly recognized as one of the most relevant pathways in HCC and agents targeting this axis can potentially play an important role in the treatment of HCC.

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.

A human monoclonal antibody against insulin-like growth factor-II blocks the growth of human hepatocellular carcinoma cell lines in vitro and in vivo

Elevated expression of insulin-like growth factor-II (IGF-II) is frequently observed in a variety of human malignancies, including breast, colon, and liver cancer. As IGF-II can deliver a mitogenic signal through both IGF-IR and an alternately spliced form of the insulin receptor (IR-A), neutralizing the biological activity of this growth factor directly is a potential alternative option to IGF-IR-directed agents. Using a Fab-displaying phage library and a biotinylated precursor form of IGF-II (1-104 amino acids) as a target, we isolated Fabs specific for the E-domain COOH-terminal extension form of IGF-II and for mature IGF-II. One of these Fabs that bound to both forms of IGF-II was reformatted into a full-length IgG, expressed, purified, and subjected to further analysis. This antibody (DX-2647) displayed a very high affinity for IGF-II/IGF-IIE (K(D) value of 49 and 10 pmol/L, respectively) compared with IGF-I (approximately 10 nmol/L) and blocked binding of IGF-II to IGF-IR, IR-A, a panel of insulin-like growth factor-binding proteins, and the mannose-6-phosphate receptor. A crystal complex of the parental Fab of DX-2647 bound to IGF-II was resolved to 2.2 A. DX-2647 inhibited IGF-II and, to a lesser extent, IGF-I-induced receptor tyrosine phosphorylation, cellular proliferation, and both anchorage-dependent and anchorage-independent colony formation in various cell lines. In addition, DX-2647 slowed tumor progression in the Hep3B xenograft model, causing decreased tumoral CD31 staining as well as reduced IGF-IIE and IGF-IR phosphorylation levels. Therefore, DX-2647 offers an alternative approach to targeting IGF-IR, blocking IGF-II signaling through both IGF-IR and IR-A.

Reactivation of the insulin-like growth factor-II signaling pathway in human hepatocellular carcinoma

Constitutive activation of the insulin-like growth factor (IGF)-signaling axis is frequently observed in human hepatocellular carcinoma (HCC). Especially the overexpression of the fetal growth factor IGF-II, IGF-Ireceptor (IGF-IR), and cytoplasmic downstream effectors such as insulin-receptor substrates (IRS) contribute to proliferation, anti-apoptosis, and invasive behavior. This review focuses on the relevant alterations in this signaling pathway and independent in vivo models that support the central role IGF-II signaling during HCC development and progression. Since this pathway has become the center of interest as a target for potential anti-cancer therapy in many types of malignancies, various experimental strategies have been developed, including neutralizing antibodies and selective receptor kinase inhibitors, with respect to the specific and efficient reduction of oncogenic IGF-II/IGF-IR-signaling.

[Molecular pathogenesis of hepatocellular carcinoma: new therapeutic approaches and predictive pathology]

Hepatocellular carcinoma is one of the most prevalent malignancies worldwide and its incidence is increasing. Multimodal strategies directed towards this carcinoma include primary (e.g. immunisation) and secondary (e.g. antiviral therapy) prevention, surgical approaches, novel specific systemic therapies (targeted therapy), and the treatment of comorbidity (cirrhosis). New molecular approaches are currently under development. These tackle several specific targets, with pathology being challenged in many aspects: experimental evaluation, the development of valid tumor-relevant diagnostic tests as well as morphological evaluation in the context of clinical studies, and finally in routine diagnosis.

IGF-II promoter methylation and ovarian cancer prognosis

PURPOSE

The insulin-like growth factor-II (IGF-II) gene has four promoters that produce distinct transcripts which vary by tissue type and developmental stage. Dysregulation of normal promoter usage has been shown to occur in cancer; DNA methylation regulates promoter use. Thus, we sought to examine if DNA methylation varies among IGF-II promoters in ovarian cancer and if methylation patterns are related to clinical features of the disease.

STUDY DESIGN

Tumor tissue, clinical data, and follow-up information were collected from 215 patients diagnosed with primary epithelial ovarian cancer. DNA extracted from tumor tissues was analyzed for IGF-II promoter methylation with seven methylation specific PCR (MSP) assays: three for promoter 2 (P2) and two assays each for promoters 3 and 4 (P3 and P4).

RESULTS

Methylation was found to vary among the seven assays: 19.3% in P2A, 45.6% in P2B, 50.9% in P2C, 48.4% in P3A, 13.1% in P3B, 5.1% in P4A, and 6.1% in P4B. Methylation in any of the three P2 assays was associated with high tumor grade (P = 0.043), suboptimal debulking (P = 0.036), and disease progression [hazards ratio (HR) = 1.73, 95% confidence interval (CI) 1.09-2.74]. When comparing promoter methylation patterns, differential methylation of P2 and P3 was found to be associated with disease prognosis; patients with P3 but not P2 methylation were less likely to have disease progression (HR = 0.39, 95% CI 0.17-0.91) compared to patients with P2 but not P3 methylation.

CONCLUSIONS

This study shows that methylation varies among three IGF-II promoters in ovarian cancer and that this variation seems to have biologic implications as it relates to clinical features and prognosis of the disease.

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.

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.

Expression and alteration of insulin-like growth factor II-messenger RNA in hepatoma tissues and peripheral blood of patients with hepatocellular carcinoma

AIM: To investigate the clinical values of serum free insulin-like growth factor II (IGF-II) levels and IGF-II mRNA in hepatocellular carcinoma (HCC) tissues and peripheral blood for diagnosis of HCC and monitoring of extrahepatic metastasis.

METHODS: Total RNAs were extracted from HCC tissues or peripheral blood mononuclear cells from patients with HCC, liver diseases devoid of cancer, non-hepatic tumors, and healthy controls, respectively. IGF-II cDNAs were synthesized through random primers and reverse-transcriptase, amplified by polymerase chain reaction (PCR), and confirmed by DNA sequencing analysis. Serum free IGF-II levels in patients with different liver diseases were analyzed by an enzyme-linked immunosorbent assay.

RESULTS: The amplified fragments of IGF-II mRNA by RT-PCR were identical to originally designed ones with a size of 170 bp and confirmed by sequencing analysis. The dilution experiments revealed that the lowest sensitivity of our system was 2 ng/L of total RNA. The positive frequencies of IGF-II mRNA were 100% in HCC tissues, 53.3% in para-cancerous tissues, and 0% in non-cancerous tissues, respectively. The serum free IGF-II levels were significantly higher in HCC than those in chronic hepatitis or liver cirrhosis. The positive frequency of circulating IGF-II mRNA was 34.2% in HCC, no amplified fragment was found in other liver diseases, extrahepatic tumors, and normal controls, respectively. The circulating IGF-II mRNA correlated with the stage of HCC, and its positive rate was 100% in HCC with extrahepatic metastasis and 35.5% in HCC with AFP-negative. No significant correlation was found between tumor sizes and circulating IGF-II mRNA fragment.

CONCLUSION: The abnormal expressions of free IGF-II and IGF-II mRNA are useful tumor markers for HCC diagnosis, differentiation of extrahepatic metastasis and monitoring postoperative recurrence.

Expression of hepatoma-derived growth factor in hepatocarcinogenesis

BACKGROUND AND AIM

The present study investigated the expression of hepatoma-derived growth factor (HDGF) in human hepatocellular carcinoma (HCC) and in the liver during hepatocarcinogenesis in two rodent models.

METHODS

Expression of HDGF was analyzed using northern blotting and immunohistochemistry in the human and rodent models.

RESULTS

Hepatoma-derived growth factor was more highly expressed in HCC than in the adjacent liver in humans with hepatitis, as shown by northern blotting. Using immunohistochemistry with the specific anti-HDGF antibody, HDGF was more strongly and frequently expressed in the nucleus and cytoplasm of HCC cells than in the adjacent normal hepatocytes. Hepatoma-derived growth factor was also more strongly expressed in the tumors than in the adjacent fatty liver of fatty liver Shionogi (FLS) mice, than in the cirrhotic liver of choline-deficient amino acid feeding rats, as shown by northern blotting and immunohistochemistry. In the liver of FLS mice, HDGF expression increased gradually from the age of 24 weeks through to 52 weeks after birth, showing that HDGF expression was already increased at an early stage before tumor development. In the non-tumorous liver with fatty change, the foci expressing HDGF appeared at 24 weeks of age, which were the activated macrophage clusters with enhanced DNA synthesis and fat droplets. It is suggested that HDGF was secreted or released from these foci and stimulated hepatocyte proliferation in a paracrine manner in FLS mice, and stimulated the proliferation of hepatic tumor cells in an autocrine manner.

CONCLUSIONS

The present findings suggest that HDGF plays an important role in the development or progression of HCC in humans and rodents.

Serum levels of insulin-like growth factor (IGF)-I and II in patients with liver diseases

AIM

To investigate the serum levels and their clinical significance of insulin-like growth factor (IGF)-I, IGF-II in patients of liver diseases.

METHODS

89 patients with liver diseases were divided into three groups. hepatitis (n = 10), cirrhosis (n = 66) and liver cancer (n = 13) group. 38 healthy people were served as control group. The serum levels of IGF-I and IGF-II were measured by RIA.

RESULTS

The serum levels of IGF-I and IGF-II in cirrhotic group (65 ± 14 mg/L, 328 ± 86 mg/L, respectively) and cancer group (49 ± 14 mg/L, 194± 61 mg/L, respectively) were significantly lower than controls (261 ± 75 mg/L, 1 094 ±119 mg/L, respectively). In cirrhotic patients, IGF-I and IGF-II were significantly higher in Child A than those in Child B/C (P<0.05, respectively). The concentrations of IGF-I and IGF-II correlated significantly with different etiology of cirrhosis (P<0.05, respectively).

CONCLUSION

The serum level of IGF-II, as well as that of IGF-I, was an important index to assess the liver function of patients with cirrhosis or liver cancer.

Activation of the IGF-II gene by HBV-X protein requires PKC and p44/p42 map kinase signalings

We have recently shown that HBx protein, one of the causative agents of hepatocellular carcinomas, regulates Sp1 mediated transcription of insulin-like growth factor II promoter 4 (Lee et al. (1998) Oncogene 16, 2367-2380). Here we show that PKC and p44/p42MAPK signalings are required for the HBx-induced Sp1-mediated IGF-II P4 transcriptional activity since (i) PKC activation by PMA or PKC expression vector increases Sp1 phosphorylation and P4 activity in HBx-transfected HepG2 cells; (ii) PKC inhibition by PKC inhibitor Gö6976 reduces Sp1 phosphorylation, P4 activity, and IGF-II mRNA in HBx-transfected HepG2 cells; and (iii) the inhibition of MEK activation by U0126 reduces Sp1 phosphorylation, P4 activity and IGF-II mRNA in HBx-transfected HepG2 cells. These results demonstrate that PKC and p44/p42 MAPK cascades are the essential signaling pathways in Sp1-mediated IGF-II gene activation by HBx.

The effects of insulin-like growth factors on tumorigenesis and neoplastic growth

Several decades of basic and clinical research have demonstrated that there is an association between the insulin-like growth factors (IGFs) and neoplasia. We begin with a brief discussion of the function and regulation of expression of the IGFs, their receptors and the IGF-binding proteins (IGFBPs). A number of investigational interventional strategies targeting the GH or IGFs are then reviewed. Finally, we have assembled the available scientific knowledge about this relationship for each of the major tumor types. The tumors have been grouped together by organ system and for each of the major tumors, various key elements of the relationship between IGFs and tumor growth are discussed. Specifically these include the presence or absence of autocrine IGF-I and IGF-II production; presence or absence of IGF-I and IGF-II receptor expression; the expression and functions of the IGFBPs; in vitro and in vivo experiments involving therapeutic interventions; and available results from clinical trials evaluating the effect of GH/IGF axis down-regulation in various malignancies.

Molecular and cellular pathology of hepatocellular carcinoma

Mutations of the p53 gene are common in hepatocellular carcinoma (HCC) and have been found in 13-33% of HCC in Asia and 23% of HCC in Hong Kong. In addition, p53 overexpression has been found to be associated with poorer cellular differentiation and larger tumour size and may be a late event in hepatocarcinogenesis. The p53 gene is important in controlling cell cycle, apoptosis and DNA repair. The cyclin-dependent kinase inhibitor p21^WAF1/CIP1 , which is downstream of p53, is regulated by both p53-dependent and p53-independent pathways. We found that HCC with p53 mutations had lower levels of p21 expression than those without p53 mutations. Moreover, p21 protein expression of the tumours was significantly higher in the tumours than in the corresponding non-tumorous livers. When the tumours were stratified into two groups, those with higher expression were found to have a significantly lower incidence of multiple tumour nodules and lower incidence of tumour microsatellite formation. p21 Expression was, however, not associated with p53 expression. Higher p21 expression is associated with solitary tumour nodules and fewer tumour microsatellites, but may not be enough to suppress tumour progression. Insulin-like growth factor II (IGF-II) gene has complex regulation of transcription resulting in multiple mRNA being produced and different mRNA occur in the adult and foetus. Using northern blot analysis, repression of normal adult promoter and re-expression of foetal promoters of IGF-II are common events in HCC, with repression of the normal adult promoter in 93% of the HCC transcripts and re-expression of the foetal transcripts (6 and 5 kb, respectively) in 40% of tumours. In addition, IGF-II expression was significantly more frequent in older patients. This may suggest that spontaneous expression of IGF-II late in life may promote the growth of tumours which have already arisen through other mechanisms, but foetal re-expression, itself, may not be enough to contribute to tumour progression.