Dysregulation of growth factor signaling in human hepatocellular carcinoma

Increased apoptosis induction in hepatocellular carcinoma by a novel tumor-targeted TRAIL fusion protein combined with bortezomib

As the result of an increasing incidence and a prevalent therapy resistance of hepatocellular carcinoma (HCC), there is a strong need for novel strategies to enhance treatment responses in HCC. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) has been proposed as a promising anticancer drug because it can selectively induce apoptosis in cancer cells, but not in healthy cells. Nevertheless, most tumor cells show TRAIL resistance, emphasizing the requirement for apoptosis-sensitizing agents and TRAIL molecules with improved tumor specificity. In this study, we employed a recombinant TRAIL molecule, in which three TRAIL protomers were expressed as a single polypeptide chain (scTRAIL), and a novel TRAIL variant, in which scTRAIL was additionally fused to an antibody fragment recognizing epidermal growth factor receptor (EGFR) to improve its HCC-targeting properties. We analyzed the proapoptotic effects of both TRAIL versions in combination with the proteasome inhibitor bortezomib (BZB) in hepatoma cells and primary human hepatocytes as well as in intact explants from HCC and healthy liver tissue. We demonstrate that EGFR-targeted TRAIL in combination with BZB induced significantly higher caspase activation and cell death in hepatoma cells, but not in primary hepatocytes. Importantly, when incubated with fresh liver explants, the combination of EGFR-targeted TRAIL and BZB displayed selective cytotoxicity for HCC, but not for tumor-free liver tissue, which could even be verified in liver explants from the same individuals. Unlike nontargeted TRAIL, EGFR-targeted TRAIL combined with BZB exerted no toxicity in liver tissues from nonalcoholic fatty liver disease patients.

CONCLUSION

EGFR-targeted TRAIL reveals increased antitumor activity toward HCC without inducing toxicity to tumor-free liver tissue and might therefore represent a promising novel strategy for HCC treatment.

Targeting IGF-IR with ganitumab inhibits tumorigenesis and increases durability of response to androgen-deprivation therapy in VCaP prostate cancer xenografts

Prostate cancer is the most commonly diagnosed malignancy in men. While tumors initially respond to androgen-deprivation therapy, the standard care for advanced or metastatic disease, tumors eventually recur as castration-resistant prostate cancer (CRPC). Upregulation of the insulin-like growth factor receptor type I (IGF-IR) signaling axis drives growth and progression of prostate cancer by promoting proliferation, survival, and angiogenesis. Ganitumab (formerly AMG 479) is a fully human antibody that inhibits binding of IGF-I and IGF-II to IGF-IR. We evaluated the therapeutic value of ganitumab in several preclinical settings including androgen-dependent prostate cancer, CRPC, and in combination with androgen-deprivation therapy. Ganitumab inhibited IGF-I-induced phosphorylation of the downstream effector AKT and reduced proliferation of multiple androgen-dependent and castration-resistant human prostate cancer cell lines in vitro. Ganitumab inhibited androgen-dependent VCaP xenograft growth and increased tumor-doubling time from 2.3 ± 0.4 weeks to 6.4 ± 0.4 weeks. Ganitumab blocked growth of castration-resistant VCaP xenografts for over 11.5 weeks of treatment. In contrast, ganitumab did not have appreciable effects on the castration-resistant CWR-22Rv1 xenograft model. Ganitumab was most potent against VCaP xenografts when combined with complete androgen-deprivation therapy (castration). Tumor volume was reduced by 72% after 4 weeks of treatment and growth suppression was maintained over 16 weeks of treatment. These data suggest that judicious use of ganitumab particularly in conjunction with androgen-deprivation therapy may be beneficial in the treatment of prostate cancer.

WNT signalling pathways as therapeutic targets in cancer

Since the initial discovery of the oncogenic activity of WNT1 in mouse mammary glands, our appreciation for the complex roles for WNT signalling pathways in cancer has increased dramatically. WNTs and their downstream effectors regulate various processes that are important for cancer progression, including tumour initiation, tumour growth, cell senescence, cell death, differentiation and metastasis. Although WNT signalling pathways have been difficult to target, improved drug-discovery platforms and new technologies have facilitated the discovery of agents that can alter WNT signalling in preclinical models, thus setting the stage for clinical trials in humans.

The inflammatory microenvironment in hepatocellular carcinoma: a pivotal role for tumor-associated macrophages

Hepatocellular carcinoma (HCC) is one of the most common and aggressive human cancers worldwide. HCC is an example of inflammation-related cancer and represents a paradigm of the relation occurring between tumor microenvironment and tumor development. Tumor-associated macrophages (TAMs) are a major component of leukocyte infiltrate of tumors and play a pivotal role in tumor progression of inflammation-related cancer, including HCC. Several studies indicate that, in the tumor microenvironment, TAMs acquire an M2-polarized phenotype and promote angiogenesis, metastasis, and suppression of adaptive immunity through the expression of cytokines, chemokines, growth factors, and matrix metalloproteases. Indeed, an established M2 macrophage population has been associated with poor prognosis in HCC. The molecular links that connect cancer cells and TAMs are not completely known, but recent studies have demonstrated that NF-κB, STAT-3, and HIF-1 signaling pathways play key roles in this crosstalk. In this paper, we discuss the current knowledge about the role of TAMs in HCC development, highlighting the role of TAM-derived cytokines, chemokines, and growth factors in the initiation and progression of liver cancer and outlining the signaling pathways involved in the interplay between cancer cells and TAMs.

Methylome analysis and integrative profiling of human HCCs identify novel protumorigenic factors

To identify new tumor-suppressor gene candidates relevant for human hepatocarcinogenesis, we performed genome-wide methylation profiling and vertical integration with array-based comparative genomic hybridization (aCGH), as well as expression data from a cohort of well-characterized human hepatocellular carcinomas (HCCs). Bisulfite-converted DNAs from 63 HCCs and 10 healthy control livers were analyzed for the methylation status of more than 14,000 genes. After defining the differentially methylated genes in HCCs, we integrated their DNA copy-number alterations as determined by aCGH data and correlated them with gene expression to identify genes potentially silenced by promoter hypermethylation. Aberrant methylation of candidates was further confirmed by pyrosequencing, and methylation dependency of silencing was determined by 5-aza-2'-deoxycytidine (5-aza-dC) treatment. Methylation profiling revealed 2,226 CpG sites that showed methylation differences between healthy control livers and HCCs. Of these, 537 CpG sites were hypermethylated in the tumor DNA, whereas 1,689 sites showed promoter hypomethylation. The hypermethylated set was enriched for genes known to be inactivated by the polycomb repressive complex 2, whereas the group of hypomethylated genes was enriched for imprinted genes. We identified three genes matching all of our selection criteria for a tumor-suppressor gene (period homolog 3 [PER3], insulin-like growth-factor-binding protein, acid labile subunit [IGFALS], and protein Z). PER3 was down-regulated in human HCCs, compared to peritumorous and healthy liver tissues. 5-aza-dC treatment restored PER3 expression in HCC cell lines, indicating that promoter hypermethylation was indeed responsible for gene silencing. Additionally, functional analysis supported a tumor-suppressive function for PER3 and IGFALS in vitro.

CONCLUSION

The present study illustrates that vertical integration of methylation data with high-resolution genomic and transcriptomic data facilitates the identification of new tumor-suppressor gene candidates in human HCC.

miR-106b downregulates adenomatous polyposis coli and promotes cell proliferation in human hepatocellular carcinoma

Aberrant activation of the Wnt/β-catenin signal pathway is frequently observed in hepatocellular carcinoma (HCC). β-Catenin is the major cellular effector of Wnt signaling and inactivation of adenomatous polyposis coli (APC) results in nuclear accumulation of β-catenin. Therefore, it was speculated that APC inhibition could play important roles in activating the Wnt/β-catenin pathway and in HCC progression. In this study, we report that miR-106b expression is markedly upregulated in hepatoma cells and hepatoma tissues compared with immortalized normal liver epithelial cells and normal hepatic tissues. Ectopic expression of miR-106b induces the proliferation and anchorage-independent growth of hepatoma cells, whereas inhibition of miR-106b reduced this effect. Furthermore, miR-106b upregulation in hepatoma cells modulated entry into the G(1)/S transitional phase by upregulating cyclin D1 and downregulating APC. Moreover, we demonstrated that miR-106b downregulates APC expression by directly targeting the 3'-untranslated region of APC messenger RNA. Taken together, our results suggest that miR-106b plays an important role in promoting the proliferation of human hepatoma cells and presents a novel mechanism of micro RNA-mediated direct suppression of APC expression in cancer cells.

Hepatitis C virus and cellular stress response: implications to molecular pathogenesis of liver diseases

Infection with hepatitis C virus (HCV) is a leading risk factor for chronic liver disease progression, including steatosis, cirrhosis, and hepatocellular carcinoma. With approximately 3% of the human population infected worldwide, HCV infection remains a global public health challenge. The efficacy of current therapy is still limited in many patients infected with HCV, thus a greater understanding of pathogenesis in HCV infection is desperately needed. Emerging lines of evidence indicate that HCV triggers a wide range of cellular stress responses, including cell cycle arrest, apoptosis, endoplasmic reticulum (ER) stress/unfolded protein response (UPR), and autophagy. Also, recent studies suggest that these HCV-induced cellular responses may contribute to chronic liver diseases by modulating cell proliferation, altering lipid metabolism, and potentiating oncogenic pathways. However, the molecular mechanism underlying HCV infection in the pathogenesis of chronic liver diseases still remains to be determined. Here, we review the known stress response activation in HCV infection in vitro and in vivo, and also explore the possible relationship of a variety of cellular responses with the pathogenicity of HCV-associated diseases. Comprehensive knowledge of HCV-mediated disease progression shall shed new insights into the discovery of novel therapeutic targets and the development of new intervention strategy.

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.

Recombinant viral protein VP1 suppresses HER-2 expression and migration/metastasis of breast cancer

Breast cancer is one of the most common cancers in women worldwide and metastasis is the major cause of breast cancer death. Development of new therapeutic agents for inhibiting breast cancer metastasis is therefore an urgent need. We previously demonstrated that recombinant DNA-derived viral capsid protein VP1 (rVP1) of foot-and-mouth disease virus-induced apoptosis of MCF-7 breast cancer cells in vitro. Here, we investigated whether rVP1 exhibits any inhibitory effects on migration/metastasis and human epidermal growth factor receptor 2 (HER-2), a well-known biomarker for poor prognosis of breast cancer. The effects of rVP1 on cancer cell migration/invasion and metastasis were evaluated using Transwell migration assay and animal cancer models of metastasis. Western blotting, RT-PCR, flow cytometry, immunohistochemistry, and immunofluorescence staining techniques were used to investigate the effects of rVP1 on HER-2 and signal transduction mediators. Non-cytotoxic concentrations of rVP1-induced mesenchymal-epithelial transition and significantly suppressed AP-2α and HER-2 expression as well as the migration and invasion of a variety of breast cancer cell lines in a β1-integrin-dependent manner in vitro. Gross and histopathologic examinations showed that rVP1 also suppressed metastasis of several breast cancer cell lines, including HER-2-overexpressing SK-BR-3 and BT-474 cells to lung, liver, or peripheral lymph node in orthotopic allograft/xenograft murine models. In addition, rVP1 significantly prolonged survival in breast cancer-bearing mice. Notably, no apparent side effects of rVP1 were detected, as shown by normal complete blood count levels and serum biochemistry profiles, including AST, ALT, BUN, and creatine. This study demonstrates that rVP1 suppresses the migration, invasion, and metastasis of breast cancer cells via binding to β1 integrin receptor and down-regulation of AP-2α and HER-2 expression. The effectiveness of rVP1 on inhibiting migration/metastasis of breast cancer and HER-2 expression suggests that it may be suitable for serving as potential therapeutics for metastatic breast cancer particularly HER-2-overexpressing cancer.

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.

Nanog regulates self-renewal of cancer stem cells through the insulin-like growth factor pathway in human hepatocellular carcinoma

Hepatocellular carcinoma (HCC) exhibits cellular heterogeneity and embryonic stem-cell-related genes are preferentially overexpressed in a fraction of cancer cells of poorly differentiated tumors. However, it is not known whether or how these cancer cells contribute to tumor initiation and progression. Here, our data showed that increased expression of pluripotency transcription factor Nanog in cancer cells correlates with a worse clinical outcome in HCC. Using the Nanog promoter as a reporter system, we could successfully isolate a small subpopulation of Nanog-positive cells. We demonstrate that Nanog-positive cells exhibited enhanced ability of self-renewal, clonogenicity, and initiation of tumors, which are consistent with crucial hallmarks in the definition of cancer stem cells (CSCs). Nanog(Pos) CSCs could differentiate into mature cancer cells in in vitro and in vivo conditions. In addition, we found that Nanog(Pos) CSCs exhibited resistance to therapeutic agents (e.g., sorafenib and cisplatin) and have a high capacity for tumor invasion and metastasis. Knock-down expression of Nanog in Nanog(Pos) CSCs could decrease self-renewal accompanied with decreased expression of stem-cell-related genes and increased expression of mature hepatocyte-related genes. Overexpression of Nanog in Nanog(Neg) cells could restore self-renewal. Furthermore, we found that insulin-like growth factor (IGF)2 and IGF receptor (IGF1R) were up-regulated in Nanog(Pos) CSCs. Knock-down expression of Nanog in Nanog(Pos) CSCs inhibited the expression of IGF1R, and overexpression of Nanog in Nanog(Neg) cells increased the expression of IGF1R. A specific inhibitor of IGF1R signaling could significantly inhibit self-renewal and Nanog expression, indicating that IGF1R signaling participated in Nanog-mediated self-renewal.

CONCLUSION

These data indicate that Nanog could be a novel biomarker for CSCs in HCC, and that Nanog could play a crucial role in maintaining the self-renewal of CSCs through the IGF1R-signaling pathway.

Synergism of EGFR and c-Met pathways, cross-talk and inhibition, in non-small cell lung cancer

Background

c-Met and EGFR receptors are widely expressed on cancer cells; they are implicated in the development and progression of cancer through a plethora of effects on cell cycle progression, apoptosis, motility and metastasis and are potential targets for combination therapy. EGFR receptor tyrosine kinases are currently being targeted in a number of malignancies.

Methods

Apoptosis was studied by FACS analysis using propidium iodide. EGF and HGF signaling intermediates were studied by western blotting. Cell proliferation was determined by MTT assays. Cell motility was done by time lapse confocal microscopy.

Results

c-Met and EGFR were both expressed in A549, H1838, H2170, SW900, SW1573, H358, SKLU-1, and H1993 non small cell lung cancer (NSCLC) cell lines. Both EGF and HGF at 100 ng/ml in medium showed a synergistic effect on cell proliferation at 48–72 h as seen by a proliferation assay in A549, H1838, and SKMES cells. In A549 and H1838 cell lines, HGF (40 ng/ml) and EGF (5 ng/ml) induced synergistic phosphorylation on c-Met (Tyr 1003/1230/1234/1235). Additionally, synergistic phosphorylation of Akt (Ser-473) and phospho-ERK1+ERK2 (Thr202/Tyr204) was also seen indicating that EGF and HGF could induce synergistic phosphorylation of important signaling intermediates. Treatment with EGF and HGF at 100 ng/ml for 2 h also leads to an additive effect in inducing cell motility (especially membrane ruffling) in H1993 cells. A novel c-Met small molecule tyrosine kinase inhibitor SU11274 and EGFR tyrosine kinase inhibitors Tyrphostin AG1478 and gefitinib (Iressa) were tested to study their effect in combination on proliferation and apoptosis in lung cancer cells. Interestingly, a synergistic effect on inhibition of cell proliferation was seen in the presence of SU11274 and Tyrphostin AG1478. 0.5 µM Tyrphostin AG1478 and 2 µM SU11274 inhibited growth by 21% and 25%, respectively; a combination of both tyrosine kinase inhibitors inhibited growth by 65%. Interestingly, EGFR inhibitor (gefitinib, Iressa) and c-Met inhibitor (SU11274) also had a synergistic effect on apoptosis in H358 cells.

Conclusion

There was a synergistic effect of EGF and HGF on proliferation, downstream activation of signal transduction and an additive effect seen on motility. These studies show that a combination of HGF and EGF tyrosine kinase inhibitors on NSCLC, could potentially be targeted in a synergistic fashion.

Inhibition of hepatocellular carcinoma cell growth by an anti-insulin-like growth factor-I receptor monoclonal antibody

Hepatocellular carcinoma (HCC) overexpresses insulin-like growth factor-I receptor (IGF-IR), as compared with normal hepatocytes. Since IGF-1R-mediated signaling promotes survival, oncogenic transformation and tumor growth and spread, it represents a potential target for treating HCC. Here, we have generated a murine anti-IGF-1R antibody, 4F2, that recognizes the IGF-IRα subunit and blocks in vitro IGF-I and IGF-II-induced cell proliferation of SMMC-7721 and Bel-7402 HCC cell lines. 4F2 can inhibit IGF-IR autophosphorylation, IRS-1 phosphorylation and the activation of the major downstream signaling molecules AKT and mitogen-activated protein kinase. Additionally, we observed a moderate increase in apoptosis as demonstrated by detection of changes in the expression of the pro-apoptotic and anti-apoptotic proteins Bax and Bcl-2 after 4F2 treatment. Combined treatment with 4F2 and doxorubicin was more effective in reducing cell proliferation and promoting apoptosis than either agent alone. These data support that therapeutic anti-IGF-IR antibodies are potential new agents for treating HCC.

Transcriptional regulators in hepatocarcinogenesis--key integrators of malignant transformation

Hepatocellular carcinoma (HCC) is one of the most frequent human malignancies with poor prognosis and increasing incidence in the Western world. Only for a minority of HCC patients, surgical treatment options offer potential cure and therapeutic success of pharmacological approaches is limited. Highly specific approaches (e.g., kinase inhibitors) did not significantly improve the situation so far, possibly due to functional compensation, genetic heterogeneity of HCC, and development of resistance under selective pressure. In contrast, transcriptional regulators (especially transcription factors and co-factors) may integrate and process input signals of different (oncogenic) pathways and therefore represent cellular bottlenecks that regulate tumor cell biology. In this review, we want to summarize the current knowledge about central transcriptional regulators in human hepatocarcinogenesis and their potential as therapeutic target structures. Genomic and transcriptomic data of primary human HCC revealed that many of these factors showed up in subgroups of HCCs with a more aggressive phenotype, suggesting that aberrant activity of transcriptional regulators collect input information to promote tumor initiation and progression. Therefore, expression and dysfunction of transcription factors and co-factors may gain relevance for diagnostics and therapy of HCC.

Inhibition of autocrine IGF-II on effect of human HepG2 cell proliferation and angiogenesis factor expression

Abnormal expression of insulin-like growth factor II (IGF-II) is associated with the hepatocyte malignant transformation and hepatocellular carcinoma (HCC) progress. In this study, specific IGF-II miRNA plasmids were constructed and transfected to HepG2 cells to knockdown IGF-II expression for observing effects on the cell proliferation, survival, apoptosis, angiogenesis, and anchorage-independent colony formation. IGF-II mRNA was evaluated by quantitative real-time polymerase chain reaction, and the level of IGF-II or vascular endothelial growth factor (VEGF) was quantitatively analyzed by ELISA. Our data shown that downregulation of IGF-II expression resulted in the viability alteration, proliferation inhibition, and apoptosis occurrence of HepG2 cells. The level of VEGF expression in the supernatant of HepG2 cells in the IGF-II-miRNA-transfected group was significantly decreasing (P < 0.01) than those in the untransfected group or the miRNA-neg-transfected group, with the susceptibility to anoikis and decreasing of anchorage-independent colony formation of HepG2 cells. Thus, we conclude that IGF-II is a potential molecular target for HCC gene therapy.

Hepatocellular carcinoma in non-alcoholic fatty liver disease: an emerging menace

Hepatocellular carcinoma (HCC) is a common cancer worldwide that primarily develops in cirrhosis resulting from chronic infection by hepatitis B virus and hepatitis C virus, alcoholic injury, and to a lesser extent from genetically determined disorders such as hemochromatosis. HCC has recently been linked to non-alcoholic fatty liver disease (NAFLD), the hepatic manifestation of obesity and related metabolic disorders such as diabetes. This association is alarming due to the globally high prevalence of these conditions and may contribute to the rising incidence of HCC witnessed in many industrialized countries. There is also evidence that NAFLD acts synergistically with other risk factors of HCC such as chronic hepatitis C and alcoholic liver injury. Moreover, HCC may complicate non-cirrhotic NAFLD with mild or absent fibrosis, greatly expanding the population potentially at higher risk. Major systemic and liver-specific molecular mechanisms involved include insulin resistance and hyperinsulinemia, increased TNF signaling pathways, and alterations in cellular lipid metabolism. These provide new targets for prevention, early recognition, and effective treatment of HCC associated with NAFLD. Indeed, both metformin and PPAR gamma agonists have been associated with lower risk and improved prognosis of HCC. This review summarizes current evidence as it pertains to the epidemiology, pathogenesis, and prevention of NAFLD-associated HCC.

Hepatitis C virus-host interactions: Etiopathogenesis and therapeutic strategies

Hepatitis C virus (HCV) is a significant health problem facing the world. This virus infects more than 170 million people worldwide and is considered the major cause of both acute and chronic hepatitis. Persons become infected mainly through parenteral exposure to infected material by blood transfusions or injections with nonsterile needles. Although the sexual behavior is considered as a high risk factor for HCV infection, the transmission of HCV infection through sexual means, is less frequently. Currently, the available treatment for patients with chronic HCV infection is interferon based therapies alone or in combination with ribavirin and protease inhibitors. Although a sustained virological response of patients to the applied therapy, a great portion of patients did not show any response. HCV infection is mostly associated with progressive liver diseases including fibrosis, cirrhosis and hepatocellular carcinoma. Although the focus of many patients and clinicians is sometimes limited to that problem, the natural history of HCV infection (HCV) is also associated with the development of several extrahepatic manifestations including dermatologic, rheumatologic, neurologic, and nephrologic complications, diabetes, arterial hypertension, autoantibodies and cryglobulins. Despite the notion that HCV-mediated extrahepatic manifestations are credible, the mechanism of their modulation is not fully described in detail. Therefore, the understanding of the molecular mechanisms of HCV-induced alteration of intracellular signal transduction pathways, during the course of HCV infection, may offer novel therapeutic targets for HCV-associated both hepatic and extrahepatic manifestations. This review will elaborate the etiopathogenesis of HCV-host interactions and summarize the current knowledge of HCV-associated diseases and their possible therapeutic strategies.

A New Player in the Development of TRAIL Based Therapies for Hepatocarcinoma Treatment: ATM Kinase

Hepatocellular carcinoma (HCC) is one of the most common cancers worldwide. HCCs are genetically and phenotypically heterogeneous tumors characterized by very poor prognosis, mainly due to the lack, at present, of effective therapeutic options, as these tumors are rarely suitable for radiotherapy and often resistant to chemotherapy protocols. In the last years, agonists targeting the Tumor Necrosis Factor Related Apoptosis Inducing Ligand (TRAIL) death receptor, has been investigated as a valuable promise for cancer therapy, based on their selectivity for malignant cells and low toxicity for healthy cells. However, many cancer models display resistance to death receptor induced apoptosis, pointing to the requirement for the development of combined therapeutic approaches aimed to selectively sensitize cancer cells to TRAIL. Recently, we identified ATM kinase as a novel modulator of the ability of chemotherapeutic agents to enhance TRAIL sensitivity. Here, we review the biological determinants of HCC responsiveness to TRAIL and provide an exhaustive and updated analysis of the molecular mechanisms exploited for combined therapy in this context. The role of ATM kinase as potential novel predictive biomarker for combined therapeutic approaches based on TRAIL and chemotherapeutic drugs will be closely discussed.

Loss of Wnt5a and Ror2 protein in hepatocellular carcinoma associated with poor prognosis

AIM: To investigate the expression and clinical significance of Wnt member 5a (Wnt5a) and receptor tyrosine kinase-like orphan receptor 2 (Ror2) in hepatocellular carcinoma (HCC).

METHODS: HCC tissues obtained from 85 patients were examined the mRNA expression of Ror2 by real-time reverse transcription polymerase chain reaction and the protein expressions of Wnt5a, Ror2, β-catenin and Ki-67 via immunohistochemical staining. The correlation between protein expression and HCC patients’ clinicopathology data and prognoses were analyzed.

RESULTS: Compared to nontumorous (hepatitis or cirrhotic) tissues, Ror2 mRNA expression was clearly decreased in HCC. Ror2 and Wnt5a protein expressions in the majority of HCC patients (63% and 77%, respectively) was significantly less in tumor tissues, as compared to adjacent nontumorous tissues, and this reduction was correlated with increasing serum α-fetoprotein and tumor stage. In 68% (58/85) of the HCC cases, the expression of β-catenin in tumor tissues was either downregulated in the cellular membrane, upregulated in the cytoplasm, or both. Survival analysis indicated that Wnt5a and Ror2 protein expressions could be regarded as independent prognostic factors for HCC; HCC patients with decreased Wnt5a or Ror2 protein expression had a poorer prognosis than those with elevated Wnt5a and Ror2 expression (P = 0.016, P = 0.007, respectively).

CONCLUSION: Wnt5a and Ror2 may serve as tumor suppressor genes in the development of HCC, and may serve as clinicopathologic biomarkers for prognosis in HCC patients.

Epidermal growth factor gene polymorphism and risk of hepatocellular carcinoma: a meta-analysis

BACKGROUND

Hepatocarcinogenesis is a complex process that may be influenced by many factors, including polymorphism in the epidermal growth factor (EGF) gene. Previous work suggests an association between the EGF 61*A/G polymorphism (rs4444903) and susceptibility to hepatocellular carcinoma (HCC), but the results have been inconsistent. Therefore, we performed a meta-analysis of several studies covering a large population to address this controversy.

METHODS

PubMed, EMBASE, Google Scholar and the Chinese National Knowledge Infrastructure databases were systematically searched to identify relevant studies. Data were abstracted independently by two reviewers. A meta-analysis was performed to examine the association between EGF 61*A/G polymorphism and susceptibility to HCC. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated.

RESULTS

Eight studies were chosen in this meta-analysis, involving 1,304 HCC cases (1135 Chinese, 44 Caucasian and 125 mixed) and 2,613 controls (1638 Chinese, 77 Caucasian and 898 mixed). The EGF 61*G allele was significantly associated with increased risk of HCC based on allelic contrast (OR = 1.29, 95% CI = 1.16-1.44, p<0.001), homozygote comparison (OR = 1.79, 95% CI = 1.39-2.29, p<0.001) and a recessive genetic model (OR = 1.34, 95% CI = 1.16-1.54, p<0.001), while patients carrying the EGF 61*A/A genotype had significantly lower risk of HCC than those with the G/A or G/G genotype (A/A vs. G/A+G/G, OR = 0.66, 95% CI = 0.53-0.83, p<0.001).

CONCLUSION

The 61*G polymorphism in EGF is a risk factor for hepatocarcinogenesis while the EGF 61*A allele is a protective factor. Further large and well-designed studies are needed to confirm this conclusion.

Downregulating hypoxia-inducible factor-2α improves the efficacy of doxorubicin in the treatment of hepatocellular carcinoma

The hypoxic microenvironment inside solid tumors, including hepatocellular carcinoma (HCC), is a major cause of tumor resistance to chemotherapy. The recently identified hypoxia-inducible factor (HIF)-2 executes the hypoxia response. Its expression feature and transcriptional targets indicate a possible dominance of HIF-2 in regulating genes in HCC. The aim of the present study was to determine whether transfection of siRNA targeting HIF-2α could enhance the efficacy of doxorubicin, the most commonly used drug in the treatment of HCC. Transfection of HIF-2 siRNA into human HCC cells downregulated the expression of HIF-2α, vascular endothelial growth factor (VEGF), transforming growth factor (TGF)-α, and cyclin D1, but had little effect on the expression of HIF-1α, fms-related tyrosine kinase-1 (Flt-1), the glucose transporter (GLUT)-1, and lactate dehydrogenase A (LDHA). Doxorubicin itself only downregulated VEGF expression. Furthermore, HIF-2 siRNA inhibited proliferation, induced cell cycle arrest at the G(0)/G(1) phase, and acted synergistically with doxorubicin to inhibit the growth of human HCC cells in vitro. Transfection of HIF-2 siRNA also downregulated tumoral expression of HIF-2α, VEGF, TGF-α, and cyclin D1 in vivo, and acted synergistically with doxorubicin to suppress the growth of HepG2 tumors established in immunodeficient mice by inhibiting cell proliferation, tumor angiogenesis and microvessel perfusion. The results of the present study suggest that targeting HIF-2α with siRNA warrants investigation as a potential strategy to enhance the efficacy of doxorubicin in the treatment of HCC.

Suppression by heat shock protein 20 of hepatocellular carcinoma cell proliferation via inhibition of the mitogen-activated protein kinases and AKT pathways

Heat shock protein (HSP) 20, one of the low-molecular weight HSPs, is known to have versatile functions, such as vasorelaxation. However, its precise role in cancer proliferation remains to be elucidated. While HSP20 is constitutively expressed in various tissues including the liver, we have previously reported that HSP20 protein levels in human hepatocellular carcinoma (HCC) cells inversely correlate with the progression of HCC. In this study, we investigated the role of HSP20 in HCC proliferation. The activities of extracellular signal-regulated kinase (ERK), c-jun N-terminal kinase (JNK), and AKT were negatively correlated with the HSP20 protein levels in human HCC tissues. Since HSP20 proteins were hardly detected in HCC-derived cell lines, the effects of HSP20 expression were evaluated using human HCC-derived HuH7 cells that were stably transfected with wild-type human HSP20 (HSP20 overexpressing cells). In HSP20 overexpressing cells, cell proliferation was retarded, and the activation of the mitogen-activated protein kinases (MAPKs) signaling pathways, including the ERK and JNK, and AKT pathways, as well as cyclin D1 accumulation induced by either transforming growth factor-α (TGFα) or hepatocyte growth factor, were significantly suppressed compared with the empty vector-transfected cells (control cells). Taken together, our findings strongly suggest that HSP20 suppresses the growth of HCC cells via the MAPKs and AKT signaling pathways, thus suggesting that the HSP20 could be a new therapeutic target for HCC.

CIIA functions as a molecular switch for the Rac1-specific GEF activity of SOS1

CIIA mediates the TGF-β–induced activation of SOS1–Rac1 signaling and cell migration.

Son of sevenless 1 (SOS1) is a dual guanine nucleotide exchange factor (GEF) that activates the guanosine triphosphatases Rac1 and Ras, which mediate signaling initiated by peptide growth factors. In this paper, we show that CIIA is a new binding partner of SOS1. CIIA promoted the SOS1–Rac1 interaction and inhibited the SOS1–Ras interaction. Furthermore, CIIA promoted the formation of an SOS1–EPS8 complex and SOS1-mediated Rac1 activation, whereas it inhibited SOS1-mediated activation of Ras. Transforming growth factor β (TGF-β) up-regulated the expression of CIIA and thereby promoted the association between CIIA and SOS1 in A549 human lung adenocarcinoma cells. Depletion of CIIA in these cells by ribonucleic acid interference inhibited the TGF-β–induced interaction between SOS1 and EPS8, activation of Rac1, and cell migration. Together, these results suggest that CIIA mediates the TGF-β–induced activation of SOS1–Rac1 signaling and cell migration in A549 cells. They further show that CIIA functions as a molecular switch for the GEF activity of SOS1, directing this activity toward Rac1.

Watch the GAP: Emerging Roles for IQ Motif-Containing GTPase-Activating Proteins IQGAPs in Hepatocellular Carcinoma

IQ motif-containing GTPase-activating proteins IQGAP1 and IQGAP2 are highly homologous multidomain scaffolding proteins. Their major function consists of integration of Rho GTPase and Ca(2+)/calmodulin signals with cell adhesive and cytoskeletal reorganizational events. Recent studies showed that they play an important role in carcinogenesis. There is growing evidence that IQGAP2 is a novel tumor suppressor counteracting the effects of IQGAP1, an oncogene, in several cancers, especially in hepatocellular carcinoma (HCC). While HCC is highly prevalent and one of the deadliest cancers worldwide, the signaling pathways involved are not fully understood and treatment of advanced disease still represents an area of high unmet medical need. This paper compiles various findings from studies in mouse models, cell lines, and patient samples that support future development of IQGAPs into new therapeutic targets. It also discusses distinct features of IQGAP2 in an attempt to provide insight into the mechanism of the seemingly paradoxical opposing roles of the two very similar IQGAP proteins in carcinogenesis.

The MAPK MEK1/2-ERK1/2 Pathway and Its Implication in Hepatocyte Cell Cycle Control

Primary cultures of hepatocytes are powerful models in studying the sequence of events that are necessary for cell progression from a G0-like state to S phase. The models mimic the physiological process of hepatic regeneration after liver injury or partial hepatectomy. Many reports suggest that the mitogen-activated protein kinase (MAPK) ERK1/2 can support hepatocyte proliferation in vitro and in vivo and the MEK/ERK cascade acts as an essential element in hepatocyte responses induced by the EGF. Moreover, its disregulation has been associated with the promotion of tumor cell growth of a variety of tumors, including hepatocellular carcinoma. Whereas the strict specificity of action of ERK1 and ERK2 is still debated, the MAPKs may have specific biological functions under certain contexts and according to the differentiation status of the cells, notably hepatocytes. In this paper, we will focus on MEK1/2-ERK1/2 activations and roles in normal rodent hepatocytes in vitro and in vivo after partial hepatectomy and in human hepatocarcinoma cells. The possible specificity of ERK1 and ERK2 in normal and transformed hepatocyte will be discussed in regard to other differentiated and undifferentiated cellular models.

Coexpression of activated c-Met and death receptor 5 predicts better survival in colorectal carcinoma

Dysregulated overexpression of hepatocyte growth factor and its receptor, c-Met, has been reported in various cancers, but its role in colorectal carcinoma (CRC) has not been elucidated. Therefore, we investigated the role of phosphorylated Met (p-Met) in Middle Eastern CRC patient samples and cell lines. The p-Met was overexpressed in 80.8% of CRCs and strongly associated with the expression of p-AKT, DR5, and Ki-67 by immunohistochemistry. Coexpression of p-Met and DR5 was seen in 53.1% of CRC cases and was associated with a less aggressive phenotype, characterized by a histological subtype of adenocarcinomas, well-differentiated tumors, and was an independent prognostic marker for better overall survival. PHA665752, a selective p-Met inhibitor, induced apoptosis in CRC cells via inactivation of c-Met and AKT. PHA665752 treatment also caused increased expression of DR5 via generation of reactive oxygen species, and combination treatment with tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) and PHA665752 induced significant apoptosis. In vivo, cotreatment of a CRC xenograft with PHA665752 and TRAIL significantly reduced tumor volume and weight. These data demonstrate a significant correlation between p-Met and DR5 in patients with CRC. Furthermore, inhibition of p-Met signaling by PHA665752 in combination with TRAIL significantly inhibited cell growth and induced apoptosis in CRC cell lines, suggesting that this may have significant clinical implications as a therapeutic target in the treatment of CRC.

Enhancement of canonical Wnt/β-catenin signaling activity by HCV core protein promotes cell growth of hepatocellular carcinoma cells

BACKGROUND

The Hepatitis C virus (HCV) core protein has been implicated as a potential oncogene or a cofactor in HCV-related hepatocellular carcinoma (HCC), but the underlying mechanisms are unknown. Overactivation of the Wnt/β-catenin signaling is a major factor in oncogenesis of HCC. However, the pathogenesis of HCV core-associated Wnt/β-catenin activation remains to be further characterized. Therefore, we attempted to determine whether HCV core protein plays an important role in regulating Wnt/β-catenin signaling in HCC cells.

METHODOLOGY

Wnt/β-catenin signaling activity was investigated in core-expressing hepatoma cells. Protein and gene expression were examined by Western blot, immunofluorescence staining, RT-qPCR, and reporter assay.

PRINCIPAL FINDINGS

HCV core protein significantly enhances Tcf-dependent transcriptional activity induced by Wnt3A in HCC cell lines. Additionally, core protein increases and stabilizes β-catenin levels in hepatoma cell line Huh7 through inactivation of GSK-3β, which contributes to the up-regulation of downstream target genes, such as c-Myc, cyclin D1, WISP2 and CTGF. Also, core protein increases cell proliferation rate and promotes Wnt3A-induced tumor growth in the xenograft tumor model of human HCC.

CONCLUSIONS/SIGNIFICANCE

HCV core protein enhances Wnt/β-catenin signaling activity, hence playing an important role in HCV-associated carcinogenesis.

Hepatocellular carcinoma: management of an increasingly common problem

Hepatocellular carcinoma (HCC) is a common cancer that typically occurs in the setting of cirrhosis and chronic hepatitis virus infections. Hepatitis B and C account for approximately 80% of cases worldwide. HCC is currently the fifth most common malignancy in men and the eighth in women worldwide; its incidence is increasing dramatically in many parts of the world. Recognition of those at risk and early diagnosis by surveillance with imaging, with or without serologic testing, are extremely important. Many highly effective and even curative therapies are now available and include resection, liver transplantation, and local ablation. Appropriate application of these interventions offers hope of prolonged survival to many patients with this otherwise lethal complication of liver disease.

Clinicopathological and prognostic significance of serum and tissue Dickkopf-1 levels in human hepatocellular carcinoma

BACKGROUND

Although Dickkopf-1 (DKK1) is known to be a negative regulator of the Wnt/β-catenin pathway, it has been recently found to be upregulated in cancers.

AIMS

We investigated the clinical and prognostic significance of both serum and transcript DKK1 and its functional roles in human hepatocellular carcinoma (HCC).

METHODS

We evaluated the expression level of DKK1 in both tissue and serum samples from patients with HCC using GeneChip microarray and real-time-quantitative PCR and sandwich ELISA system respectively. The clinicopathological and prognostic significance of serum and tissue DKK1 levels was examined. Functional characterization of DKK1 with regard to cell migration, invasion and tumour growth was performed.

RESULTS

Both DKK1 transcript and serum protein were upregulated in a stepwise manner in human HCCs. Its transcript levels were associated with more aggressive tumour behaviour, in terms of venous invasion (P = 0.003), advanced tumour stage (P = 0.003). DKK1 transcript correlated with shorter overall (P = 0.006) and disease-free survival (P = 0.012), and higher serum DKK1 levels correlated with shorter disease-free survival (P = 0.046). Knockdown of DKK1 significantly reduced both migratory and invasive abilities of HCC cells, whereas overexpression of DKK1 enhanced the tumour formation efficiency and tumour growth in vivo.

CONCLUSIONS

Serum and tissue DKK1 levels increased in a stepwise manner in multistep hepatocarcinogenesis and had prognostic significance. DKK1 plays a functional role in cell migration, invasion and tumour growth.

Minimal cooperation between mutant Hras and c-myc or TGFα in the regulation of mouse hepatocyte growth or transformation in vivo

BACKGROUND

Liver carcinogenesis is associated with multiple genetic changes in affected cells, including alterations in the Hras signalling pathway.

AIM

To define the biological contributions of Hras to mouse hepatocarcinogenesis, we quantified in vivo interactions between mutant Hras and other genetic alterations frequently associated with liver cancer, including overexpression of the transcription factor c-myc and the epidermal growth factor receptor ligand transforming growth factor alpha (TGFα).

METHODS

To accomplish this aim, we initiated expression of an activated Hras in hepatocytes of adult mice with or without simultaneous overexpression of either c-myc or TGFα. Potential interactions also were assessed through the use of the comparative hepatocyte growth assay, a hepatocyte transplantation assay that measures effects of altered gene expression on hepatocyte growth in vivo.

RESULTS

Hras expression caused diffuse liver enlargement (hepatomegaly), and this phenotype was not changed by coexpression of c-myc or TGFα. Using the transplant system, we found that expression of mutant Hras alone was sufficient to induce hepatocyte focus growth in a quiescent liver. Paradoxically, adding expression of TGFα or c-myc reversed this Hras effect. Finally, the frequencies of transplant foci with the preneoplastic feature of extreme growth potential and of liver neoplasms were increased for Hras and both combinations when compared with control hepatocytes, but did not differ among oncogene-expressing groups.

CONCLUSIONS

Hras-associated hepatocyte growth deregulation is not complemented by activation of c-myc or TGFα growth signalling pathways in mouse liver. This finding emphasizes the tissue-specific character of molecular growth regulation.

Platelet-derived growth factor regulates breast cancer progression via β-catenin expression

OBJECTIVE

The knowledge on the association between platelet-derived growth factor (PDGF) signaling and epithelial cancers is scarce, although overexpression of PDGF and PDGF receptors has been reported in some human mesenchymal tumors. Thus, we studied the effect of PDGF on breast cancer cells in vitro and the distribution of PDGF in breast cancer tissues.

METHODS

The effect of PDGF-BB on breast cancer cells was assessed by Western blotting, immunofluorescence, WST and 5-bromo-2-deoxyuridine incorporation experiments. PDGF-B and β-catenin expression was investigated in breast cancer tissues by immunohistochemistry.

RESULTS

PDGF-BB induces β-catenin expression in breast cancer cells, and immunohistochemically the distribution of PDGF-B was similar to β-catenin in breast cancer cells. PDGF-B-positive cancer cells were more frequent in cases of ductal carcinoma in situ (87.5%) than invasive carcinoma (61.2%). In addition, PDGF-B staining was stronger in intraductal than invasive cancer cells. PDGF-BB tended to induce nuclear translocation of β-catenin, cell proliferation and DNA incorporation in MDA-MB231 cells, while these results were not found in MCF-7 cells.

CONCLUSION

Our results suggest that PDGF-BB regulates protein expression of β-catenin and is associated with cancer cell behavior.

Molecularly targeted therapies for hepatocellular carcinoma: sorafenib as a stepping stone

Since sorafenib, a multikinase inhibitor targeting angiogenesis of hepatocellular carcinoma (HCC), demonstrated survival benefits in recent clinical trials, it has changed the treatment paradigm and become the standard first-line treatment for patients with advanced HCC. However, disease stabilization with sorafenib lasts a few months, possibly due to the development of resistance, and thus the survival advantage was modest, even in patients with preserved liver function. Furthermore, there is currently no biomarker for monitoring the response or resistance to sorafenib. Currently, various kinds of molecularly targeted agents have been developed and are being evaluated in clinical trials. There are several steps required to improve the outcome from sorafenib therapy. First, a reliable predictive and prognostic biomarker is urgently needed. Second, a compelling indication of sorafenib treatment for HCC needs more clinical studies and consensus. Third, the actual benefits of sorafenib to patients with advanced liver dysfunction should be clarified and a more effective strategy for targeted therapy needs to be developed, for example, using a combination of targeted agents acting on different pathways or different levels of a key pathway. Finally, sorafenib could be used with other treatment modalities, such as local ablation or transarterial chemoembolization, to synergize efficacy. Based on the successful introduction of sorafenib, future studies should focus on plans to further improve the outcome of HCC patients by overcoming resistance and maximizing the efficacy of molecularly targeted therapy.

Cluster analysis of indicators of liver functional and preoperative low branched-chain amino acid tyrosine ration indicate a high risk of early recurrence in analysis of 165 hepatocellular carcinoma patients after initial hepatectomy

BACKGROUND

Cluster analysis is used for dividing many prognostic indicators, including liver function, tumor progression, and operative variables, into specific clusters. The albumin (ALB), hepatocyte growth factor (HGF), and branched chain amino-acid to tyrosine ratio (BTR) may represent the severity of liver disease and function of the hepatic reserve. We developed the ALB-BTR and HGF-BTR classifications depending on each level to find specific unique subgroups. Our aim was to identify specific subgroups destined for favorable and poor prognoses after initial hepatectomy.

METHODS

Between 2002 and 2008, 165 patients were analyzed retrospectively. Liver function indicators, including BTR, tumor-related factors, and operative variables, were evaluated by cluster analysis with Ward's criterion. The ALB-BTR classification was divided into 4 groups depending on ALB (cutoff value, 4.0 g/dL) and BTR (cutoff value, 6.0). The HGF-BTR classification was also divided into 4 groups depending on HGF (cutoff value, 0.35 ng/mL) and BTR (cutoff value, 6.0). The prognoses of the subgroups were compared by the log-rank test.

RESULTS

Cluster analysis divided multiple indicators into 5 different clusters. In each cluster, we further analyzed subgroups using the ALB-BTR and HGF-BTR classification. Mean recurrence-free survival times in ALB-GI (19.1 ± 2.4 months) and HGF-GIII (29.4 ± 3.8 months) were less than their mean overall survival times.

CONCLUSION

Cluster analysis is useful to find similar and different indicators. Even though liver function was well preserved, low BTR could identify early recurrence in hepatocellular carcinoma patients after resection.

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.

Hepatocyte growth factor upregulation promotes carcinogenesis and epithelial-mesenchymal transition in hepatocellular carcinoma via Akt and COX-2 pathways

Advanced hepatocellular carcinoma (HCC) is an important cause of cancer mortality. Epithelial-mesenchymal transition (EMT) has been shown to be an important biological process in cancer progression and metastasis. We have focused on elucidating factors that induce EMT to promote carcinogenesis and subsequent metastasis in HCC using the BNL CL.2 (BNL) and BNL 1ME A. 7R.1 (1MEA) cell lines. BNL cells are normal hepatocytes whereas the 1MEA cells are HCC cells derived from chemical transformation of the BNL cells. Their morphological characteristics were examined. Expression levels of hepatocyte growth factor (HGF), markers of EMT and mediators of HGF signaling were determined and functional characteristics were compared. BNL cells were treated with HGF and effects on EMT-marker and mediators of HGF signaling were analyzed. BNL cells display characteristic epithelial morphology whereas 1MEA cells display mesenchymal characteristics. 1MEA cells express and secrete more HGF than BNL cells. There was significantly decreased expression of E-cadherin, albumin, AAT and increased expression of fibronectin, collagen-1, vimentin, snail and slug in 1MEA cells. There was also increased expression of cyclooxygenase-2 (COX-2), Akt and phosphorylated Akt (pAkt) in 1MEA cells. Moreover, 1MEA cells had increased migratory capacity inhibited by inhibition of COX-2 and Akt but not extracellular signal regulated kinase (ERK). Molecular mesenchymal characteristics of 1MEA cells were reversed by inhibition of COX-2, Akt and ERK. Treatment of BNL cells with HGF led to decreased expression of E-cadherin and increased expression of fibronectin, vimentin, snail, slug, COX-2, Akt, pAkt and increased migration, invasiveness and clonogenicity. We conclude that development of HCC is associated with upregulation of HGF which promotes EMT and carcinogenesis via upregulation of COX-2 and Akt. Consequently, HGF signaling may be targeted for therapy in advanced and metastatic HCC.

Suppression of amphiregulin/epidermal growth factor receptor signals contributes to the protective effects of quercetin in cirrhotic rats

The hepatic wound-healing response to chronic noxious stimuli may lead to liver fibrosis, a key feature of the preneoplastic cirrhotic liver. Fibrogenic cells activate in response to a variety of cytokines, growth factors, and inflammatory mediators. The involvement of members of the epidermal growth factor family in this process has been suggested. Amphiregulin is an epidermal growth factor receptor (EGFR) ligand specifically induced upon liver injury. We investigated the effects of quercetin on the amphiregulin/EGFR signal and on the activation of downstream pathways leading to cell growth. Rats were divided into 4 groups (8 rats/group): rats subjected to common bile duct ligation (CBDL), Sham (rats subjected to simulated CBDL), quercetin-treated sham, and quercetin-treated CBDL (CBDL-Q). Quercetin (50 mg/kg i.p. injection) was administered daily for 2 wk starting on d 14 after surgery. Overexpression of amphiregulin, EGFR, TNFα, IL-6, TGFβ, platelet-derived growth factor (PDGF), extracellular regulated kinase, protein kinase B (Akt), cycloxygenase (COX)-2, and glioma-associated oncogenes (GLI)-1 and-2 were observed in liver of CBDL rats after 4 wk of bile duct ligation. CBDL-Q rats had a significantly diminished expression of amphiregulin and EGFR compared with untreated CBDL rats. Furthermore, mRNA levels of TNFα, IL-6, TGFβ, and PDGF and the protein content of COX-2, GLI-1, and GLI-2 were significantly lower in CBDL-Q rats than in untreated CBDL rats. The findings indicate that quercetin ameliorated activation of survival pathways and downregulated the expression of genes related to inflammation and precancerous conditions. Suppression of amphiregulin/EGFR signals may contribute to this effect.

Strategies for hepatocellular carcinoma therapy and diagnostics: lessons learned from high throughput and profiling approaches

Over the last decade, numerous small and high-dimensional profiling analyses have been performed in human hepatocellular carcinoma (HCC), which address different levels of regulation and modulation. Because comprehensive analyses are lacking, the following review summarizes some of the general results and compares them with insights from other tumor entities. Particular attention is given to the impact of these results on future diagnostic and therapeutic approaches.

Expression of insulin-like growth factor-II, matrix metalloproteinases, and their tissue inhibitors as predictive markers in the peripheral blood of HCC patients

BACKGROUND/AIM

Elevated relative expression of insulin-like growth factor-II (IGF-II) was observed in hepatocellular carcinoma (HCC) liver tissues with a role in neovascularization and associated with poor prognosis. IGF-II is influenced by the proteolytic cleavage of IGF-binding protein 3 and by matrix metalloproteinases (MMP), which are further regulated by their tissue inhibitors tissue inhibitor of metalloprotienase-1 (TIMP-1). Our aim is to study new molecular markers for HCC.

PATIENTS/METHODS

RNA was extracted from the peripheral blood for evaluating the relative expression of IGF-II, MMP-9, and TIMP-1 in correlation with clinical staging of 39 HCC patients and 15 healthy controls using TaqMan real-time PCR.

RESULTS

The relative expression of IGF-II and MMP-9 mRNA were significantly elevated in HCC patients compared with healthy controls; P-value <0.0001 for both. There was a significant correlation between MMP-9 and different HCC stages. On the other hand, TIMP-1 was significantly down-regulated in HCC patients; P = 0.0003 with the elevation of the IGF-II/TIMP-1 ratio. Significant correlation between TIMP-1 and HCC Stage III and Stage IV was found; P-value = 0.0138.

CONCLUSION

These results highlight the importance of profiling the expression of IGF-II, MMP-9, and TIMP-1 in the peripheral blood as prognostic molecular biomarkers in HCC.

Epidermal Growth Factor Receptor (EGFR) Crosstalks in Liver Cancer

Hepatocarcinogenesis is a complex multistep process in which many different molecular pathways have been implicated. Hepatocellular carcinoma (HCC) is refractory to conventional chemotherapeutic agents, and the new targeted therapies are meeting with limited success. Interreceptor crosstalk and the positive feedback between different signaling systems are emerging as mechanisms of targeted therapy resistance. The identification of such interactions is therefore of particular relevance to improve therapeutic efficacy. Among the different signaling pathways activated in hepatocarcinogenesis the epidermal growth factor receptor (EGFR) system plays a prominent role, being recognized as a “signaling hub” where different extracellular growth and survival signals converge. EGFR can be transactivated in response to multiple heterologous ligands through the physical interaction with multiple receptors, the activity of intracellular kinases or the shedding of EGFR-ligands. In this article we review the crosstalk between the EGFR and other signaling pathways that could be relevant to liver cancer development and treatment.

Hepatocellular carcinoma: molecular and genomic guideline for the clinician

Understanding of the genetic changes and molecular signaling pathways that are active in hepatocellular carcinoma has improved substantially over the last decade. As more information becomes available, it is clear that the prognostication of hepatocellular carcinoma will soon include molecular and genomic "fingerprints" that are unique to each cancer, which will allow more personalized treatment plans for patients as more targeted therapies become available. This article discusses the molecular and genomic changes that are important in hepatocellular carcinoma in order for clinicians to understand the current and forthcoming treatment options for patients with liver cancer.

Novel therapeutic strategies for targeting liver cancer stem cells

The cancer stem cell (CSC) hypothesis was first proposed over 40 years ago. Advances in CSC isolation were first achieved in hematological malignancies, with the first CSC demonstrated in acute myeloid leukemia. However, using similar strategies and technologies, and taking advantage of available surface markers, CSCs have been more recently demonstrated in a growing range of epithelial and other solid organ malignancies, suggesting that the majority of malignancies are dependent on such a compartment.Primary liver cancer consists predominantly of hepatocellular carcinoma (HCC) and intrahepatic cholangiocarcinoma (ICC). It is believed that hepatic progenitor cells (HPCs) could be the origin of some HCCs and ICCs. Furthermore, stem cell activators such as Wnt/β-catenin, TGF-β, Notch and Hedgehog signaling pathways also expedite tumorigenesis, and these pathways could serve as molecular targets to assist in designing cancer prevention strategies. Recent studies indicate that additional factors such as EpCAM, Lin28 or miR-181 may also contribute to HCC progression by targeting HCC CSCs. Various therapeutic drugs that directly modulate CSCs have been examined in vivo and in vitro. However, CSCs clearly have a complex pathogenesis, with a considerable crosstalk and redundancy in signaling pathways, and hence targeting single molecules or pathways may have a limited benefit for treatment. Many of the key signaling molecules are shared by both CSCs and normal stem cells, which add further challenges for designing molecularly targeted strategies specific to CSCs but sparing normal stem cells to avoid side effects. In addition to the direct control of CSCs, many other factors that are needed for the maintenance of CSCs, such as angiogenesis, vasculogenesis, invasion and migration, hypoxia, immune evasion, multiple drug resistance, and radioresistance, should be taken into consideration when designing therapeutic strategies for HCC. Here we provide a brief review of molecular signaling in liver CSCs and present insights into new therapeutic strategies for targeting liver CSCs.

EZH2-mediated concordant repression of Wnt antagonists promotes β-catenin-dependent hepatocarcinogenesis

Enhancer of zeste homolog 2 (EZH2) is the catalytic subunit of the Polycomb-repressive complex 2 (PRC2) that represses gene transcription through histone H3 lysine 27 trimethylation (H3K27me3). Although EZH2 is abundantly present in various cancers, the molecular consequences leading to oncogenesis remain unclear. Here, we show that EZH2 concordantly silences the Wnt pathway antagonists operating at several subcellular compartments, which in turn activate Wnt/β-catenin signaling in hepatocellular carcinomas (HCC). Chromatin immunoprecipitation promoter array and gene expression analyses in HCCs revealed EZH2 occupancy and reduced expression of Wnt antagonists, including the growth-suppressive AXIN2, NKD1, PPP2R2B, PRICKLE1, and SFRP5. Knockdown of EZH2 reduced the promoter occupancy of PRC2, histone deacetylase 1 (HDAC1), and H3K27me3, whereas the activating histone marks were increased, leading to the transcriptional upregulation of the Wnt antagonists. Combinatorial EZH2 and HDAC inhibition dramatically reduced the levels of nuclear β-catenin, T-cell factor-dependent transcriptional activity, and downstream pro-proliferative targets CCND1 and EGFR. Functional analysis revealed that downregulation of EZH2 reduced HCC cell growth, partially through the inhibition of β-catenin signaling. Conversely, ectopic overexpression of EZH2 in immortalized hepatocytes activated Wnt/β-catenin signaling to promote cellular proliferation. In human HCCs, concomitant overexpression of EZH2 and β-catenin was observed in one-third (61/179) of cases and significantly correlated with tumor progression. Our data indicate that EZH2-mediated epigenetic silencing contributes to constitutive activation of Wnt/β-catenin signaling and consequential proliferation of HCC cells, thus representing a novel therapeutic target for this highly malignant tumor.

Latest developments in targeted therapy for hepatocellular carcinoma

The advent of sorafenib can be considered as a turning point in the history of advanced hepatocellular carcinoma. After unfortunate attempts at using chemotherapy, drugs targeting key pathways have generated new perspectives in this field. This means not only killing both tumor cells and cirrhotic fragile tissue, but killing them selectively; more than was previously possible. This seems like the Copernican Revolution. However, hepatocellular carcinoma is pathogenetically complicated, resulting from the number of mutations. Until now, there has not been a single drug able to block and reverse abnormally activated signaling in hepatocellular carcinoma cells. In this article, we describe the most promising targeted drugs being studied in hepatocellular carcinoma and depict the possible future scenarios.

[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.

Upregulation of the insulin receptor and type I insulin-like growth factor receptor are early events in hepatocarcinogenesis

The molecular mechanisms underlying the development of hepatocellular carcinoma (HCC) are not yet fully understood. Preneoplastic foci of altered hepatocytes regularly precede HCC in various species. The predominant earliest type of foci of altered hepatocytes, the glycogen storage focus (GSF), shows an excess of glycogen (glycogenosis) in the cytoplasm. During progression from GSF to HCC, the stored glycogen is gradually reduced, resulting in complete loss in basophilic HCC. We have previously shown that in N-nitrosomorpholine-induced hepatocarcinogenesis, insulin receptor substrate (IRS-1) is strongly expressed in GSF and reduced during progression to HCC, thus correlating with the glycogen content. In the present study, we observed increased levels of insulin receptor, IGF-I receptor (IGF-IR), IRS-2, and mitogen-activated kinase/extracellular regulated kinase-1 in GSF, following the same pattern of expression as IRS-1. We conclude that the abundance of IRS-1, IRS-2, and mitogen-activated kinase/extracellular regulated kinase-1 coincides with a concerted upregulation of both IR and IGF-IR induced by the hepatocarcinogen. Our data suggest that in early hepatocellular preneoplasia, the upregulation of IR elicits glycogenosis through IRS-1 and/or IRS-2, whereas the increased level of the IGF-IR may lead to the increased cell proliferation previously reported in GSF. Therefore, the concerted upregulation of both IR and IGF-IR may represent initial events in hepatocarcinogenesis.

Up-regulation of the fibroblast growth factor 8 subfamily in human hepatocellular carcinoma for cell survival and neoangiogenesis

Fibroblast growth factors (FGFs) and their high-affinity receptors [fibroblast growth factor receptors (FGFRs)] contribute to autocrine and paracrine growth stimulation in several non-liver cancer entities. Here we report that at least one member of the FGF8 subfamily (FGF8, FGF17, and FGF18) was up-regulated in 59% of 34 human hepatocellular carcinoma (HCC) samples that we investigated. The levels of the corresponding receptors (FGFR2, FGFR3, and FGFR4) were also elevated in the great majority of the HCC cases. Overall, 82% of the HCC cases showed overexpression of at least one FGF and/or FGFR. The functional implications of the deregulated FGF/FGFR system were investigated by the simulation of an insufficient blood supply. When HCC-1.2, HepG2, or Hep3B cells were subjected to serum withdrawal or the hypoxia-mimetic drug deferoxamine mesylate, the expression of FGF8 subfamily members increased dramatically. In the serum-starved cells, the incidence of apoptosis was elevated, whereas the addition of FGF8, FGF17, or FGF18 impaired apoptosis, which was associated with phosphorylation of extracellular signal-regulated kinase 1/2 and ribosomal protein S6. In contrast, down-modulation of FGF18 by small interfering RNA (siRNA) significantly reduced the viability of the hepatocarcinoma cells. siRNA targeting FGF18 also impaired the cells' potential to form clones at a low cell density or in soft agar. With respect to the tumor microenvironment, FGF17 and FGF18 stimulated the growth of HCC-derived myofibroblasts, and FGF8, FGF17, and FGF18 induced the proliferation and tube formation of hepatic endothelial cells.

CONCLUSION

FGF8, FGF17, and FGF18 are involved in autocrine and paracrine signaling in HCC and enhance the survival of tumor cells under stress conditions, malignant behavior, and neoangiogenesis. Thus, the FGF8 subfamily supports the development and progression of hepatocellular malignancy.

Advances in molecularly targeted therapy of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a fatal disease that represents the fifth most common human cancer. Although remarkable progress has been achieved in HCC treatment in China, the overall incidence and mortality rates of HCC show no obvious changes. Pharmacological treatment can not improve the prognosis of patients with unresectable HCC. This emphasizes the need to identify new targets for early diagnosis, chemoprevention, and treatment of the disease. An effort to understand the molecular mechanisms responsible for tumor initiation and progression has led to the identification of several potential molecular targets for HCC. The majority of these targets are involved in receptor tyrosine kinase-activated pathways, such as the Raf/MEK/ERK, PI-3K/Akt/mTOR, and Jak/Stat pathways. Sorafenib is a multikinase inhibitor that has attracted wide attention. This review describes the potential targets for HCC and recent progress in targeted therapy of the disease.