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

Hepatocyte Deletion of IGF2 Prevents DNA Damage and Tumor Formation in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is the fifth most common cancer worldwide. Serine-arginine rich splicing factor 3 (SRSF3) plays a critical role in hepatocyte function and its loss in mice promotes chronic liver damage and leads to HCC. Hepatocyte-specific SRSF3 knockout mice (SKO mice) also overexpress insulin-like growth factor 2 (IGF2). In the present study, double deletion of Igf2 and Srsf3 (DKO mice) prevents hepatic fibrosis and inflammation, and completely prevents tumor formation, and is associated with decreased proliferation, apoptosis and DNA damage, and restored DNA repair enzyme expression. This is confirmed in vitro, where IGF2 treatment of HepG2 hepatoma cells decreases DNA repair enzyme expression and causes DNA damage. Tumors from the SKO mice also show mutational signatures consistent with homologous recombination and mismatch repair defects. Analysis of frozen human samples shows that SRSF3 protein is decreased sixfold in HCC compared to normal liver tissue but SRSF3 mRNA is increased. Looking at public TCGA data, HCC patients having high SRSF3 mRNA expression show poor survival, as do patients with alterations in known SRSF3-dependent splicing events. The results indicate that IGF2 overexpression in conjunction with reduced SRSF3 splicing activity could be a major cause of DNA damage and driver of liver cancer.

Diabetes and hepatocellular carcinoma: A pathophysiological link and pharmacological management

Both diabetes mellitus (DM) and cancer are multifarious, dissimilar, and long-lasting, fatal diseases with a remarkable influence on health worldwide. DM is not only related to cardiovascular diseases, neuropathy, nephropathy, and retinopathy, but also related to a number of liver diseases such as nonalcoholic fatty liver disease, steatohepatitis, and liver cirrhosis. Recently, it is hypothesized that DM has a greater risk for many forms of cancer, such as breast, colorectal, endometrial, pancreatic, gallbladder, renal, and liver cancer including hepatocellular carcinoma (HCC). Both DM and cancer have many common risk factors, but the association between these two is poorly stated. Several epidemiologic studies have revealed the association between pathogenic and prognostic characteristics of DM and a higher incidence of HCC, thus representing DM as an independent risk factor for HCC development. The etiological and pathophysiological relationship between DM and HCC has been presented in this review by linking hyperglycemia, hyperinsulinemia, insulin resistance, and activation of insulin-like growth factor signaling pathways and pharmacological management of HCC associated with DM.

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.

Insulin-Like Growth Factor (IGF) System in Liver Diseases

Hepatocyte differentiation, proliferation, and apoptosis are affected by growth factors produced in liver. Insulin-like growth factor 1 and 2 (IGF1 and IGF2) act in response to growth hormone (GH). Other IGF family components include at least six binding proteins (IGFBP1 to 6), manifested by both IGFs develop due to interaction through the type 1 receptor (IGF1R). The data based on animal models and/or in vitro studies suggest the role of IGF system components in cellular aspects of hepatocarcinogenesis (cell cycle progression, uncontrolled proliferation, cell survival, migration, inhibition of apoptosis, protein synthesis and cell growth), and show that systemic IGF1 administration can reduce fibrosis and ameliorate general liver function. In epidemiologic and clinicopathological studies on chronic liver disease (CLD), lowered serum levels, decreased tissue expression of IGF1, elevated production of IGF1R and variable IGF2 expression has been noted, from the start of preneoplastic alterations up to the developed hepatocellular carcinoma (HCC) stage. These changes result in well-known clinical symptoms of IGF1 deficiency. This review summarized the current data of the complex role of IGF system components in the most common CLD (nonalcoholic fatty liver disease, cirrhosis, and hepatocellular carcinoma). Better recognition and understanding of this system can contribute to discovery of new and improved versions of current preventive and therapeutic actions in CLD.

MiR-483-5p promotes IGF-II transcription and is associated with poor prognosis of hepatocellular carcinoma

The human insulin-like growth factor-II (IGF-II) gene transcribes four mRNAs (P1 mRNA-P4 mRNA), and P3 mRNA overexpression contributes to hepatocarcinogenesis. IGF-II-derived miR-483-5p is implicated in the development of cancers. Here, we investigated the involvement of miR-483-5p in P3 mRNA overexpression regulation and its role in hepatocellular carcinoma. Our results showed that miR-483-5p up-regulated P3 mRNA transcription by targeting the 5′-untranslated region (5′UTR) of P3 mRNA in hepatocellular carcinoma. The mechanism was involved in recruiting of an argonaute 1(Ago1)-argonaute 2 (Ago2) complex to the P3 mRNA 5′UTR and the P3 promoter of IGF-II gene by miR-483-5p, accompanied by increased enrichment of RNA polymerase II and activating histone marks histone 3 lysine 4 trimethylation (H3K4me3), histone 3 lysine 27 acetylation (H3K27ac), and histone 4 lysine 5/8/12/16 acetylation (H4Kac) at the P3 promoter. High miR-483-5p expression was an independent predictor for shorter survival of HCC patients. The findings suggest that miR-483-5p promotes P3 mRNA transcription by recruiting the Ago1-Ago2 complex to the P3 mRNA 5′UTR and is associated with poor prognosis of HCC. Our results display a potential new model for miRNAs to up-regulate gene expression.

Differential Expression of Glypican-3 and Insulin–Like Growth Factor-II mRNAs and Alpha-Fetoprotein and Ki-67 Markers in HCV Related Hepatocellular Carcinomas In Egyptian Patients

Background:

Increasing evidence indicates that in hepatocellular carcinomas (HCCs) abnormal gene expression, for example of glypican-3 (GPC-3) and insulin-like growth factor-II (IGF-II), are associated with the occurrence and progression of HCC. The objective of this study was to evaluate the differential expression of GPC-3 and IGF-II mRNAs in HCC tissues with a background of chronic hepatitis C virus (HCV) genotype 4 cirrhosis, in relation to Ki-67 and alpha-feto protein (AFP) tissue markers.

Methods:

One hundred and five patients with HCCs who had undergone hepatectomy, were included, after obtaining informed consent. Total RNA was extracted from malignant and corresponding peri-malignant liver tissues, and GPC-3 and IGF-II mRNAs in addition to beta-actin mRNA as an internal control, were evaluated in all samples by reverse transcriptase-polymerase chain reactions (RT-PCR). Routine histopathological diagnosis as well as immunohistochemical (IHC) staining using monoclonal antibodies for Ki-67 and AFP were also performed.

Result:

Expression of GPC-3 mRNA was positive in all HCC malignant tissue, with overexpression in 86/105 (81.9%); in respect to the grade of the tumor (1-3 grades), while in peri-malignant tissue it was over expressed only in 20/105 (19%). The IGF-II mRNA was over expressed in only 10/105 (9.5%) malignant and peri-malignant samples. AFP was expressed in 33.3% of malignant samples but absent in peri-malignant tissues. Ki-67 expression was significantly increased in malignant compared to peri-malignant tissue.

Conclusion:

GPC-3 and IGF II mRNAs may be good molecular markers for HCC, especially with a background of cirrhosis due to chronic HCV infection. Significant correlations were noted with the pattern of AFP and Ki-67 expression.

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.

The Circulating IGF System in Hepatocellular Carcinoma: The Impact of Liver Status and Treatment

BACKGROUND

Previous studies have demonstrated an elevated IGF-II mRNA expression and protein levels in tumors and blood from patients with hepatocellular carcinoma (HCC), hereby suggesting a role of IGF-II as a pathogenic marker of HCC. We hypothesized that in HCC, an increased IGF-II secretion would translate into an elevated circulating IGF bioactivity, which would normalize following treatment.

METHODS

Patients with HCC (n=39) were studied before and after radio-frequency ablation and/or transarterial chemo-embolization. Baseline data were compared to healthy subjects (n=150) and patients with liver cirrhosis (n=41). Serum levels of IGF ligands and IGF binding proteins (IGFBPs) were determined using gold standard methods as well as novel assays and compared to liver function tests and HCC treatment status.

RESULTS

At baseline, HCC patients differed from cirrhosis patients and healthy controls regarding IGF-I (29 [23-37] vs. 12 [7-19] vs. 109 [103-116] μg/l), IGF-II (254 [224-288] vs. 118 [102-137] vs. 545 [525-566] μg/l) and IGF bioactivity (0.53 [0.41-0.68] vs. 0.29 [0.24-0.34] vs. 1.43 [1.33-1.53] μg/l) (mean [95% confidence interval], all age-adjusted P<0.001). All variables but IGFBP-2 were strongly associated with liver status (MELD score), and accordingly, differences were either attenuated or disappeared when adjusted for MELD score. There was no effect of treatment on any IGF variables.

CONCLUSIONS

The marked differences in IGF and IGFBP levels between patients with HCC, liver cirrhosis and healthy subjects are mainly explained by variations in liver status. Therefore, this study questions the clinical utility of circulating IGF variables as markers of 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.

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.

Impact of insulin-like growth factor 2, insulin-like growth factor receptor 2, insulin receptor substrate 2 genes polymorphisms on susceptibility and clinicopathological features of hepatocellular carcinoma

BACKGROUND

Hepatocellular carcinoma (HCC) is one of the major causes of cancer-related death worldwide. Insulin-like growth factor-2 (IGF-2) is an important autocrine and paracrine growth factor which may induce cell proliferation and inhibit cell apoptosis leading to the transformation of normal cells into malignant cells. This study aimed to evaluate the possible roles of IGF-2, insulin-like growth factor-2 receptor (IGF-2R), and insulin receptor substrate (IRS)-2 genes polymorphisms in susceptibility and clinicopathological features of HCC in Egyptian population.

MATERIALS AND METHODS

Four hundred and twenty-six HCC patients and 334 controls were enrolled in the study. Polymorphisms of IGF-2+3580, IGF-2+3123, IGF-2R 1619, and IRS-2 1057 gene were detected using polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP). Serum IGF-2 were determined using ELISA.

RESULTS

Serum IGF-2 levels were significantly lower in HCC patients than in healthy controls. IGF-2+3580 AA genotype, IGF-2+3123 GG genotype or G allele, IRS-2 1057 DD genotype and D allele were significantly associated with HCC risk. The combination of IGF-2+3580 AA homozygosity and IGF-2R 1619 GG homozygosity presented a significant protective effect against HCC (OR=0.16,95% CI=0. 08-0.34, P=0. 005). Serum IGF-2 concentrations were significantly increased in HCC patients with the IGF-2+3580 AA genotype. We also observed that increased alpha-fetoprotein (AFP), Child-Pugh grade, tumor size, and number of malignant lesions were accompanied by a significant increase of serum IGF-2 mean values of in HCC patients.

CONCLUSION

IGF-2, IGF-2R, and IRS-2 genes polymorphisms and their combinations are associated with risk of HCC.

Circulating specific biomarkers in diagnosis of hepatocellular carcinoma and its metastasis monitoring

Hepatocellular carcinoma (HCC) is one of the most common and rapidly fatal malignancies worldwide with a multifactorial, multistep, complex process and poor prognosis. Its early diagnosis and metastasis monitoring are of the utmost importance. Hepatoma tissues synthesize various tumor-related proteins, genes, enzymes, microRNA, etc. and then secrete into the blood. Detections of circulating biomarkers are useful to find tumor at an early stage or monitor metastasis after postoperative treatment. This paper summarizes recent studies of specific biomarkers at early diagnosis or in monitoring metastasis or postoperative recurrence of HCC.

Insulin-like growth factor-II is a useful marker to detect hepatocellular carcinoma?

BACKGROUND

Hepatocellular carcinoma (HCC) is a typical hypervascular tumor. The utility of serum alpha-fetoprotein (α-FP) in its detection is questionable. Over-expression and high circulating levels of insulin-like growth factor-II (IGF-II) were reported in tissue and in serum of patients with HCC. We investigated the diagnostic application of IGF-II in the diagnosis of HCC.

METHODS

Serum IGF-II and α-FP levels were measured in 178 patients (82 with HCC and 96 with liver cirrhosis) and in 30 healthy controls. Spearman test, non parametric combination test and confidence interval analysis were used for statistical evaluation of data.

RESULTS

The best cut-off values selected by ROC curves were 796 ng/ml for IGF-II and 132 ng/ml for α-FP. IGF-II mean values were higher in patients with HCC than in those with liver cirrhosis (LC) (p=0.0001) but lower in LC than in controls (p=0.0001). Serum IGF-II levels above cut-off were found in 22% of patients with HCC, in 9.3% of those with cirrhosis and in 20% of controls. α-FP serum levels >132 ng/ml were observed in 48% of HCC, in 3.1% of LC and in none of control group. By correlation study, serum IGF-II levels were significantly correlated with serum α-FP levels (r=0.427, p=0.0001) and with nodules' diameter (r=0.252, p=0.0130) but not with nodules' number (p>0.050). Finally, IGF-II showed lower sensitivity, specificity and predictive values than α-FP.

CONCLUSION

Circulating IGF-II is not a useful marker for HCC. Further researches are however needed to evaluate its diagnostic accuracy before and after nutritional adjustment.

Insulin-like growth factor: current concepts and new developments in cancer therapy

The insulin-like growth factor (IGF) family and the IGF-1 receptor (IGF-1R) play an important role in cancer. This intricate and complex signaling pathway provides many opportunities for therapeutic intervention, and several novel therapeutics aimed at the IGF-1R, particularly monoclonal antibodies and small molecule tyrosine kinase inhibitors, are under clinical investigation. This article provides a patent overview of the IGF signaling pathway and its complexity, addresses the justification for the use of IGF-1R-targeted therapy, and reviews the results of in vivo and in vitro novel therapeutics. Over the past year, the completion of several phase I, II, and III trials have provided interesting new information about the clinical activity of these novel compounds, particularly CP-751,871, IMC-A12, R1507, AMG-479, AVE-1642, MK-0646, XL-228, OSI-906, and BMS-754807. We review the important preliminary results from clinical trials with these compounds and conclude with a discussion about future therapeutic efforts.

Circulating tumor cells measurements in hepatocellular carcinoma

Liver cancer is the fifth most common cancer in men and the seventh in women. During the past 20 years, the incidence of HCC has tripled while the 5-year survival rate has remained below 12%. The presence of circulating tumor cells (CTC) reflects the aggressiveness nature of a tumor. Many attempts have been made to develop assays that reliably detect and enumerate the CTC during the development of the HCC. In this case, the challenges are (1) there are few markers specific to the HCC (tumor cells versus nontumor cells) and (2) they can be used to quantify the number of CTC in the bloodstream. Another technical challenge consists of finding few CTC mixed with million leukocytes and billion erythrocytes. CTC detection and identification can be used to estimate prognosis and may serve as an early marker to assess antitumor activity of treatment. CTC can also be used to predict progression-free survival and overall survival. CTC are an interesting source of biological information in order to understand dissemination, drug resistance, and treatment-induced cell death. Our aim is to review and analyze the different new methods existing to detect, enumerate, and characterize the CTC in the peripheral circulation of patients with HCC.

Epithelial-mesenchymal transition predicts sensitivity to the dual IGF-1R/IR inhibitor OSI-906 in hepatocellular carcinoma cell lines

A growing body of data indicates that inhibiting the type 1 insulin-like growth factor receptor (IGF-1R) might be an effective treatment strategy for hepatocellular carcinoma (HCC). OSI-906 is a dual IGF-1R/IR kinase inhibitor currently in phase II clinical development for HCC. However, biomarkers are lacking to help identify patients with HCC who are more likely to benefit from OSI-906 treatment. We sought to determine the effect of OSI-906 on proliferation against a panel of 21 HCC cell lines and to investigate molecular determinants of responsiveness to OSI-906. We identified a subset of HCC cell lines that was sensitive to OSI-906, and sensitivity is associated with elevated phosphorylation levels of IGF-1R and IR and greater inhibition of AKT signaling. Dual targeting of both receptors seems to be important for maximal inhibition as treatment with a selective IGF-1R-neutralizing antibody was associated with increased IR signaling, whereas OSI-906 fully inhibited both phosphorylated IR and IGF-1R and resulted in greater inhibition of the IRS/AKT pathway. Epithelial-mesenchymal transition (EMT) seems to predict HCC cell sensitivity to OSI-906, as the epithelial phenotype is strongly associated with expression of IGF-2 and IR, activation of IGF-1R and IR, and sensitivity to OSI-906, alone or in combination with erlotinib. Induction of EMT upon treatment with TGFβ reduced sensitivity to OSI-906. Collectively, these data support the concept for dual IGF-1R/IR targeting in HCC, where EMT status and expressions of IGF-2 and IR may be used to identify those patients who are most likely to benefit from treatment with an IGF-1R/IR dual inhibitor.

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

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

Recovering circulating extracellular or cell-free RNA from bodily fluids

The presence of extracellular circulating or cell-free RNA in biological fluids is becoming a promising diagnostic tool for non invasive and cost effective cancer detection. Extracellular RNA or miRNA as biological marker could be used either for the early detection and diagnosis of the disease or as a marker of recurrence patterns and surveillance. In this review article, we refer to the origin of the circulating extracellular RNA, we summarise the data on the biological fluids (serum/plasma, saliva, urine, cerebrospinal fluid and bronchial lavage fluid) of patients suffering from various types of malignancies reported to contain a substantial amount of circulating extracellular (or cell-free) RNAs and we discuss the appropriate reagents and methodologies needed to be employed in order to obtain RNA material of high quality and integrity for the majority of the experimental methods used in RNA expression analysis. Furthermore, we discuss the advantages and disadvantages of the RT-PCR or microarray methodology which are the methods more often employed in procedures of extracellular RNA analysis.

[Molecular mechanisms of progression in human hepatocarcinogenesis]

Hepatocellular carcinoma (HCC) is one of the most frequent malignant tumors worldwide with poor prognosis. Based on high-throughput screening technology, we and others have identified factors and pathways that are pivotal for tumor progression including transcription factors and microtubule-interacting proteins. In addition, aberrant activation of the IGF signalling pathway is frequently observed in HCCs which is predominantly based on high level expression of its ligand IGF-II. Because protumorigenic effects of IGF-II such as proliferation, anti-apoptosis, and migration are transmitted through its receptor IGF-1R, selective inhibition of this tyrosine kinase by small molecule compounds might reduce IGF-II-driven tumor growth. Indeed, administration of IGF-1R-selective inhibitors reduces IGF-II-induced effects and was associated with a significant reduction of tumor growth in a xenograft transplantation model. In conclusion, the IGF-II/IGF-1R signalling pathway is critically involved in the regulation of tumor growth and tumor cell dissemination, representing a promising therapeutic target structure in the treatment of HCC.

Characteristics of hepatic igf-ii expression and monitored levels of circulating igf-ii mRNA in metastasis of hepatocellular carcinoma

The prognosis of hepatocellular carcinoma (HCC) remains dismal. Insulin-like growth factor II (IGF-II), a fetal growth factor, is highly expressed during HCC development. We examined serum IGF-II levels and circulating IGF-II messenger RNA (mRNA) expression and analyzed the clinicopathologic characteristics in patients with liver diseases. The higher IGF-II level in the serum of patients with HCC could be correlated with hepatitis B virus infection but not with patient sex, age, tumor size, or α-fetoprotein (AFP) level. Total RNAs were extracted from liver tissues or peripheral blood mononuclear cells, and IGF-II complementary DNA (cDNA) and AFP cDNA were synthesized through random primers and reverse transcriptase; gene fragments were amplified by nested polymerase chain reaction and confirmed by sequencing. The incidence of the hepatic IGF-II gene was 100% in HCC, 54.3% in paracancerous tissues, and none in noncancerous tissues. The incidence rates for circulating IGF-II and AFP genes were 34.3% and 52.7%, respectively, and for both, 61.6% in patients with HCC. They were 100% in cases with extrahepatic metastasis. The IGF-II abnormality associates with HCC, and circulating IGF-II and IGF-II mRNA are useful molecular markers for HCC differential diagnosis and hematogenous metastasis.

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.

Differential roles of insulin-like growth factor receptor- and insulin receptor-mediated signaling in the phenotypes of hepatocellular carcinoma cells

Intrahepatic and extrahepatic metastases are common findings in hepatocellular carcinoma (HCC). Insulin-like growth factor 2 (IGF2) expression is frequently induced in HCC, and serum IGF2 levels correlate with the presence of extrahepatic metastases. Yet, the role of IGF-induced signaling in the dissemination of HCC remains unclear. We have previously observed elevated IGF2 levels in tumors with metastatic potential in an HCC mouse model. Here, we demonstrate that inhibition of IGF2, or its receptor IGF1R, impairs the migration and invasion activities of murine HCC cells. Furthermore, inhibition of IGF1R also impairs the ability of HCC cells to colonize the lungs after introduction into the circulation through the tail vein but does not impair subcutaneous tumor growth. Collectively, these findings suggest that IGF1R-mediated signaling plays a causative role in tumor dissemination but is not required for tumor growth per se. Although previous studies indicate that IGF ligands can signal through IGF1R/insulin receptor (IR) heterodimers, and IR-A homodimers, we demonstrate that the IR is not required for invasion and metastasis by HCC cells. Finally, we identify matrix metalloproteinase 2 as a mediator of the invasive phenotype downstream of IGF1R-induced signaling. Thus, our studies demonstrate the importance of IGF2-induced signaling in the dissemination of HCC cells.

Hepatocarcinogenesis following pancreatic islet transplantation in streptozotocin- and autoimmune-diabetic rats

Epidemiological studies assign a role to insulin signalling deregulation and diabetes mellitus in human hepatocarcinogenesis. The underlying mechanisms, however, remain largely unknown. To unravel the molecular pathogenesis of insulin-induced hepatocarcinogenesis, we generated an experimental animal model: after transplantation of only a low number of isologous pancreatic islets into the livers of diabetic rats, mild diabetes persists and the beta cells are maximally stimulated to permanently secrete insulin. As a consequence, liver acini, draining the hyperinsulinemic blood from islet grafts, show insulin-induced adaptive alterations simultaneously resembling preneoplastic foci of chemically-induced hepatocarcinogenesis models. These lesions progress to hepatocellular tumours within 6 and 24 months. Hepatocarcinogenesis is accompanied by alterations in hepatocytes metabolisms and changes in signal transduction pathways that, in the beginning, can be attributed solely to insulin action. In this review, we summarize our findings that may help understanding the oncogenic potential of diabetes mellitus in the human liver.

Autocrine insulin-like growth factor-II stimulation of tumor cell migration is a progression step in human hepatocarcinogenesis

The protumorigenic insulin-like growth factor (IGF)-II is highly expressed in a significant fraction of human hepatocellular carcinomas (HCC). However, a functional dissection that clarifies the contribution of IGF-II-binding receptors in tumor progression and a respective molecular characterization of IGF-II signaling has not been performed. Therefore, expression of IGF-II and its receptors IGF-receptor type I (IGF-IR) and insulin receptor (IR) was efficiently blocked using small interfering RNA (siRNA) in HCC cells. Despite functional IR-signaling, oncogenic IGF-II effects such as tumor cell viability, proliferation, and anti-apoptosis were solely transmitted by IGF-IR. Although IGF-II signaling was previously not described in the context of HCC cell migration, the IGF-II-dependent expression profile displayed a high percentage of genes involved in cell motility and adhesion. Indeed, IGF-II overexpression promoted HCC cell migration, especially in synergy with hepatocyte growth factor (HGF). The therapeutic relevance of IGF-II/IGF-IR signaling was tested in vitro and in a murine xenograft transplantation model using the IGF-IR inhibitor picropodophyllin (PPP). IGF-IR inhibition by small molecule treatment efficiently reduced IGF-II-dependent signaling and all protumorigenic properties of the IGF-II/IGF-IR pathway.

CONCLUSION

In human HCC cells, IGF-IR but not IR is involved in oncogenic IGF-II signaling. Autocrine stimulation of IGF-II induces HCC motility by integration of paracrine signals for full malignant competence. Thus, activation of IGF-II/IGF-IR signaling is likely a progression switch selected by function that promotes tumor cell dissemination and aggressive tumor behavior.

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.

Angiogenesis soluble factors as hepatocellular carcinoma noninvasive markers for monitoring hepatitis C virus cirrhotic patients awaiting liver transplantation

BACKGROUND

Physiological angiogenesis occurs during liver regeneration, leading to the formation of new functional sinusoids. Pathological angiogenesis occurs in hepatocellular carcinoma (HCC). We aimed to evaluate the expression of angiogenic factors in hepatitis C virus (HCV)-HCC tissues and the utility of angiogenesis soluble factors as noninvasive markers of HCC and tumor growth.

METHODS

Thirty-eight HCV-HCC tumors with 10 corresponding nontumor cirrhotic tissues, as well as 42 independent HCV cirrhotic and 6 normal liver tissues were studied using high-density oligonucleotide arrays. Human angiogenesis microarray was used for the protein detection of EGF, TIMP-1, TIMP-2, HGF, angiopn-1, angiopn-2, VEGF-A, IP-10, PDGF, KGF, angiogenin, VEGF-D, ICAM-1, and FGF in plasma samples from 40 patients (30 HCCs and 10 HCV cirrhosis).

RESULTS

From the gene expression analysis of the HCV-HCC tumors compared to normal livers, we found an important number of genes related to angiogenesis differentially expressed (alpha=0.01), including VEGF, PDGF, AGPTL2, ANG, EGFL6, EGFR, angiopn-1, angiopn-2, ICAM2, TIMP-2, among others. Moreover, angiogenic genes were also differentially expressed when HCV-HCC samples were compared to HCV cirrhotic tissues (alpha=0.01; VEGF, EGFL3, EGFR, VEGFB, among others). Ten out of 14 angiogenic proteins analyzed were statistically differentially expressed between HCV cirrhosis and HCV-HCC groups (TIMP-1, TIMP-2, HGF, angiopn-1, angiopn-2, VEGF-A, IP-10, PDGF, KGF, and FGF; P<0.05). In addition, we observed that angiopn-2 was the most significant predictor (area under the curve: 0.83).

CONCLUSION

Differentially expressed angiogenesis genes were observed between HCV patients with and without HCC. Soluble angiogenic factors might be useful for monitoring high-risk HCV patients.

Trace element concentration in primary liver cancers--a systematic review

BACKGROUND

The incidence of primary liver cancer varies between countries. Many of the etiological factors contributing to the geographical variations in incidence are unknown. Development of hepatocellular carcinoma has been linked to levels of trace elements. This review summarizes the evidence associating HCC with trace elements.

METHODS

MEDLINE, EMBASE, and CENTRAL databases were searched. Various inclusion and exclusion criteria were applied to select the articles for inclusion. Data extraction was performed using a custom designed data extraction form.

RESULTS

A total of 12,344 references were identified. Duplicates, 1,597, were excluded. Clearly irrelevant references, 10,676, were excluded through reading titles and abstracts. Some references (59) were excluded by applying the exclusion criteria. Twelve studies including 646 patients and measuring iron content (8), copper content (11), zinc (9), and selenium (2) qualified for the review. Although a meta-analysis was not possible due to heterogeneity between the studies, a clear pattern of distribution of the trace elements was discernible.

CONCLUSION

Iron and zinc content are lower in HCC than in surrounding tissues or normal controls. Copper content is lower in HCC than in surrounding tissues and cirrhotic controls. Epidemiological and physiological reasons for the trace element alterations should be further investigated.

Epithelial molecular markers in the peripheral blood of patients with colorectal cancer

Despite the modest improvements in patient survival from colorectal cancer in the last few decades, the overall five-year survival rate remains at 40 to 45 percent. Surgical resection is the mainstay of treatment for colorectal cancer; however, nearly one-half of all patients who undergo a potentially curative resection will relapse because of undetected micrometastasis. The fact that the overall survival rate remains poor strongly suggests that the dissemination of these cells occurs early in the disease process and emphasizes the need for finding feasible diagnostic methods with sufficient sensitivity and specificity. The most commonly used technique for the detection of nucleic acid material of disseminated tumor cells is the polymerase chain reaction. We critically review the literature on DNA and messenger ribonucleic acid molecular markers that have been used for the detection of circulating tumor cells in the peripheral blood of patients with colorectal cancer and other solid tumors as appropriate for comparison. The cytokeratins, particularly cytokeratin 19 and cytokeratin 20, are the most investigated prognostic markers, but even for these questions remain about their clinical value, and hence most recent studies are utilizing a combination of factors. There is an urgent need for standardized isolation and analysis techniques to be adopted thus allowing large-scale, appropriately controlled, multicenter trials to be undertaken on the most promising candidate markers.

Dynamic expression and alteration characteristic of insulin-like growth factor-Ⅱ in the carcinogenesis of hepatocellular carcinoma

AIM: To investigate the dynamic expression and alteration of insulin-like growth factor-Ⅱ(IGF-Ⅱ) during in the pathogenesis and development of hepatocellular carcinoma.

METHODS: Hepatoma models were induced with 2-fluorenylacetamide (2-FAA) in male Sprague-Dawley (SD) rats. The morphological changes of rat livers were observed by HE staining. The dynamic changes of IGF-Ⅱ in rat livers and sera were quantitatively analyzed by enzyme linked immunosorbent assay (ELISA). Simultaneously, the expression and cellular distribution of IGF-Ⅱ were detected by immunohistochemistry.

RESULTS: Histological examination confirmed that the expression of IGF-Ⅱwas increased in gradient after granule-like degeneration, atypical hyperplasia and carcinoma appeared in hepatocytes, and it was significantly higher in carcinoma group than that in degeneration and control group (carcinoma vs degeneration, χ² = 9.55, P < 0.01; carcinoma vs control, χ² = 14.00, P < 0.01). IGF-Ⅱwas positively expressed inside the liver cancer cells, and there was positive correlation between tissue and serum IGF-Ⅱ expression (r = 0.97, P < 0.01).

CONCLUSION: IGF-Ⅱ is involved in the carcinogenesis of hepatocellular carcinoma, and its expression is up-regulated at the early stage of carcinoma, which can help to achieve early diagnosis and prognosis judgment.

Signaling pathway of insulin-like growth factor-II as a target of molecular therapy for hepatoblastoma

AIM: To address the possibility that insulin-like growth factor (IGF)-II is a growth factor and its signaling pathway so as to develop a molecular therapy for hepatoblastoma.

METHODS: Huh-6 and HepG2, human hepatoblastoma cell lines, were used. IGF-II was added to the medium deprived of serum. Western blot analysis was performed to clarify the expression of IGF-I receptor (IGF-IR). Inhibitors of IGF-IR (picropodophyllin, PPP), phosphatidyl-inositol (PI) 3-kinase (LY294002 and Wortmannin), or mitogen-activated protein (MAP) kinase (PD98059) were added to unveil the signaling pathway of IGF-II. Cells were analyzed morphologically with hematoxylin-eosin staining to reveal the mechanism of suppression of cell proliferation.

RESULTS: IGF-II stimulated cells proliferated to 2.7 (269% ± 76%) (mean ± SD) (Huh-6) and 2.1 (211% ± 85%) times (HepG2). IGF-IR was expressed in Huh-6 and HepG2. PPP suppressed the cell number to 44% ± 11% (Huh-6) and 39% ± 5% (HepG2). LY294002 and Wortmannin suppressed the cell number to 30% ± 5% (Huh-6), 44% ± 0.4% (HepG2), 49% ± 1.0% (Huh-6) and 46% ± 1.1% (HepG2), respectively. PD98059 suppressed the cell number to 33% ± 11% for HepG2 but not for Huh-6. When cell proliferation was prohibited, many Huh-6 and HepG2 cells were dead with pyknotic or fragmented nuclei, suggesting apoptosis.

CONCLUSION: IGF-II was shown to be a growth factor of hepatoblastoma via IGF-I receptor and PI3 kinase which were good candidates for target of molecular therapy.

Dynamic alteration of telomerase expression and its diagnostic significance in liver or peripheral blood for hepatocellular carcinoma

AIM: To investigate the dynamic alteration of telomerase expression during development of hepatocellular carcinoma (HCC) and its diagnostic implications in liver tissues or peripheral blood mononuclear cells for HCC.

METHODS: Dynamic expressions of liver telomerase during malignant transformation of hepatocytes were observed in Sprague-Dawly (SD) rats fed with 0.05% of 2-fluoenyacetamide (2-FAA). Total RNA and telomerase were extracted from rat or human liver tissues. The telomerase activities in livers and in circulating blood were detected by a telomeric repeat amplification protocol-enzyme-linked immunosorbent assay (TRAP-ELISA), and its diagnostic value was investigated in patients with benign or malignant liver diseases.

RESULTS: The hepatoma model displayed the dynamic expression of hepatic telomerase during HCC development. The telomerase activities were consistent with liver total RNA levels (r = 0.83, P < 0.01) at the stages of degeneration, precancerosis, and cancerization of hepatocytes. In HCC patients, the telomerase levels in HCC tissues were significantly higher than in their adjacent non-cancerous tissues, but liver total RNA levels were lower in the former than in the latter. Although the circulating telomerase of HCC patients was abnormally expressed among patients with chronic liver diseases, the telomerase activity was a non-specific marker for HCC diagnosis, because the incidence was 15.7% in normal control, 25% in chronic hepatitis, 45.9% in liver cirrhosis, and 85.2% in HCC, respectively when absorbance value of telomerase activity was more than 0.2. If the value was over 0.6, the incidence was 60% in HCC group and 0% in any of the others (P < 0.01) except in two cases with liver cirrhosis. However, the combination of circulating telomerase with serum alpha-fetoprotein level could increase the positive rate and the accuracy (92.6%, 125 of 135) of HCC diagnosis.

CONCLUSION: The overexpression of telomerase is associated with HCC development, and its abnormality in liver tissues or in peripheral blood could be a useful marker for diagnosis and prognosis of HCC.

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Correlations of insulin-like growth factor-II expression with hepatitis B virus DNA replication and clinical pathological characteristics in human hepatocelullar carcinoma

AIM: To investigate the expression of insulin-like growth factor-II (IGF-II) in hepatocellular carcinoma (HCC) as well as its correlations with the pathogenesis, development and prognosis of HCC.

METHODS: IGF-II expression was detected by immunohistochemistry in 30 HCC and their corresponding non-cancerous tissues. Liver HBV DNA was detected by in situ molecular hybridization technique and the relationship was analyzed between IGF-II expression and HBV replication or the clinical pathological characteristics.

RESULTS: The stronger expression of IGF-II was found in liver cancer tissues. The positive rate of IGF-II expression was 83.3% in HCC, and 46.7% in non-cancerous liver tissues (P < 0.01), respectively. The expression of IGF-II was significantly higher in HCC with moderate or low differentiation than that with well differentiation (90.0%, 100% vs 42.9%, P < 0.05 or P < 0.01). IGF-II expression was markedly lower in HCC without serosa invasion than that with serosa invasion (95.0% vs 60.0%, P < 0.05). IGF-II expression was also correlated with tumor size (< 5 cm vs ≥ 5 cm: 58.3% vs 100%, P < 0.01), but with tumor number (P > 0.05). The level of IGF-II expression in HBV DNA-positive HCC was significantly higher than that in HBV DNA-negative ones (94.7% vs 63.6%, P < 0.05).

CONCLUSION: IGF-II is highly expressed in HCC, and the aberrant expression of IGF-II is correlated with the degree of differentiation, invasion and tumor size, and it may be used as a marker for development and prognosis of HCC.

Analysis on expression and imprinting style of small nuclear ribonucleoprotein polypeptide N in hepatic cancer cell line HepG2

AIM: To investigate the expression and imprinting style of small nuclear ribonucleoprotein polypeptide N (SNRPN) in hepatic cancer cell line HepG2.

METHODS: Human hepatic cancer cell line HepG2 was cultured in vitro by routine method. The expression of SNRPN gene in the cells was detected by reverse transcription polymerase chain reaction (RT-PCR). The single nucleotide polymorphisms (SNP) of SNRPN at exon 4 nt 1654312 (numbered according to NT_026446, SNP rs705) was genotyped in a genomic DNA sample and a cDNA sample of HepG2 cell line with restriction fragment length polymorphism (RFLP) based on RT-PCR.

RESULTS: SNRPN was stably expressed in HepG2 cells. The heterozygote C/T was found at exon 4 nt 1654312 of SNRPN. In cell lines heterozygous with respect to this SNP, only one of the two alleles (T allele) present in the genomic DNA produced an mRNA transcript.

CONCLUSION: SNRPN mRNA is expressed in HepG2 cells, and there is no loss of imprinting.