Induction of angiopoietin-2 gene expression by COX-2: a novel role for COX-2 inhibitors during hepatocarcinogenesis

Prognostic Impact of Vessels that Encapsulate Tumor Cluster (VETC) in Patients who Underwent Liver Transplantation for Hepatocellular Carcinoma

BACKGROUND

There is limited published information about prognostic value of vessels that encapsulate tumor cluster (VETC) based on their involvement with immune cells in hepatocellular carcinoma (HCC). Our goal was to evaluate prognostic impact of VETC in patients who underwent living-donor liver transplantation (LDLT) for HCC, focusing on the involvement of VETC with immune status in tumor microenvironment (TME).

METHODS

Using a database of 150 patients who underwent LDLT for HCC, immunohistochemical staining of CD34 for VETC, angiopoietin-2 (Ang-2), CD3, and CD68, was reviewed with patients' clinicopathological factors.

RESULTS

A strong correlation between VETC pattern and malignant potential in HCC was observed; larger tumor size (P < 0.001), more numbers of tumors (P = 0.003), higher α-fetoprotein levels (P = 0.001), higher des-γ-carboxy prothrombin levels (P = 0.022), microvascular invasion (P < 0.001), and poor differentiation (P = 0.010). Overall survival (OS) of patients with VETC⁽⁺⁾ was significantly lower than those with VETC^(-) (P = 0.021; 5-year OS rates, 72.0% vs. 87.1%). Furthermore, the ratio of CD3⁽⁺⁾ cells was significantly lower in VETC⁽⁺⁾ group (P = 0.001), indicating that VETC activity may be strongly correlated with lymphocyte activity. Moreover, combination status of VETC⁽⁺⁾/CD3^low was an independent risk factor for mortality (hazard ratio 2.760, 95% confidence interval 1.183-6.439, P = 0.019). Additionally, the combination of VETC expression with immune status (low CD3 levels) enabled further classification of patients based on their clinical outcome.

CONCLUSIONS

Our results show the prognostic impact of VETC expression, tumor-infiltrating lymphocytes (TILs), and their combination in the setting of LDLT for HCC, which can be a novel prognostic biomarker for mortality after LDLT.

The Angiopoietin/Tie2 Pathway in Hepatocellular Carcinoma

Due to the usually late diagnosis and lack of effective therapies, hepatocellular carcinoma (HCC), which poses a growing global health problem, is characterized by a poor prognosis. Angiogenesis plays an important role in HCC progression, and vascular endothelial growth factor (VEGF) and angiopoietins (Angs) are key drivers of HCC angiogenesis. VEGF-targeting strategies already represent an important component of today’s systemic treatment landscape of HCC, whereas targeting the Ang/Tie2 signaling pathway may harbor future potential in this context due to reported beneficial anticancer effects when targeting this pathway. In addition, a better understanding of the relation between Angs and HCC angiogenesis and progression may reveal their potential as predictive factors for post-treatment disease progression and prognosis. In this review, we give a comprehensive overview of the complex role of Ang/Tie2 signaling in HCC, pinpointing its potential value as biomarker and target for HCC treatments, aiding HCC diagnosis and therapy.

Molecular targeted therapies in hepatocellular carcinoma

In vivo tumor progression requires the supply of oxygen and nutrition by neovasculature. Hepatocellular carcinoma (HCC) is one of the typical tumors with neovascularization, and the dramatic alteration in the arterial vascularity may lead to acquisition of the potential for vascular invasiveness and metastasis. In 2008, phase III clinical trials revealed anti-angiogenic agent "sorafenib" as the first drug that demonstrated an improved overall survival in patients with advanced HCC. A new era of HCC treatment had arrived, but there has been limited further improvement in survival benefits. This review summarizes molecular targeted therapy with a focus on angiogenesis, growth signals, and mitotic abnormalities, as well as the promising concepts of "cancer stemness" and "synthetic lethality" for the strategy of targeted therapy.

Inhibition of HBV-induced angiogenesis by ibuprofen: Role of HBx

Chronic hepatitis B virus (HBV) carriers may develop hepatocellular carcinoma (HCC) by a wide range of mechanisms including angiogenesis. We show that HBV replication induces the expression of angiogenic proteins interleukin 6 (IL6) and cyclooxygenase-2 (Cox2). Interestingly, ibuprofen (a Cox2 inhibitor) is found to attenuate the levels of IL6 and Cox 2 which are induced by HBV replication.

The mechanism of attenuation of angiogenic proteins by ibuprofen was further investigated. Our results show that HBx is involved in the increase of the expression of Cox2 through the NFκB pathway. However, the expression of Cox2 is decreased when the HBx-expressing cells are incubated with ibuprofen. The contrasting effect of HBx on Cox2 is found to be determined by differential dimer formation among the members of the NFκB family of proteins, including NFκB, RelA, and C-rel. Specifically, HBx alone results in dimer formation between NFκB and RelA, while the combined presence of HBx and ibuprofen leads to the formation of NFκB and C-rel. Additional information on the interaction network involving HBx, ibuprofen, and NFκB pathways is revealed by two-dimensional liquid chromatography-tandem mass spectrometry proteomics analysis. Taken together, our findings provide new insights on the angiogenesis induced by HBV replication.

Proteomics-related biomarkers for HBV-associated hepatocellular carcinoma: current status and future prospects

HBV infection is the major cause of the development of hepatocellular carcinoma (HCC). HCC is one of the most common malignancies in the world. The morbidity rate associated with HCC is mainly linked to late diagnosis. Thus, it is very important to discover prognostic factors that can act as biomarkers for preventing HCC development, and those that can act as therapeutic targets. Proteomics analysis has been applied to identify biomarkers from clinical HCC samples. In addition, the cell-based HBV replication and viral protein overexpression system, which provides a model of the cell at an early stage of viral infection, was also used to identify biomarkers. The proteins identified at this stage may be relevant to HBV-associated HCC prognosis. In this review, we discuss the current status of proteomics analysis in the discovery of cellular proteins and prognostic HCC biomarkers, with a special focus on cell metastasis and angiogenesis.

Molecular targeted therapy for hepatocellular carcinoma in the current and potential next strategies

Hepatocellular carcinoma (HCC) is one of the most common malignancies worldwide and its incidence is still increasing. While the primary curative treatment for HCC is surgical resection, a major obstacle for the treatment of HCC is the high frequency of tumor recurrence even after curative resection. Effective palliative treatment is hindered by the evidence that HCC is frequently resistant to conventional chemotherapy and radiotherapy. Targeted therapy which specifically inhibits molecular abnormalities has emerged as a novel approach for the innovative and effective medical treatment of malignancies. In order to fulfill this promise there is an urgent need to identify the optimal targets for the treatment of HCC. A multi-kinase angiogenesis inhibitor, sorafenib, has been revealed as the first agent to show favorable overall survival in patients with advanced HCC. A new era of HCC treatment has arrived, but there has been limited improvement in survival benefits with the status quo. This review summarizes molecular targeted therapy for HCC, with a focus on angiogenesis, growth signaling, and mitosis, as well as a promising concept, "cancer stemness" for the current and potential next strategies of HCC treatment.

Molecular targeted therapy for hepatocellular carcinoma in the current and potential next strategies

Hepatocellular carcinoma (HCC) is one of the most common malignancies worldwide and its incidence is still increasing. While the primary curative treatment for HCC is surgical resection, a major obstacle for the treatment of HCC is the high frequency of tumor recurrence even after curative resection. Effective palliative treatment is hindered by the evidence that HCC is frequently resistant to conventional chemotherapy and radiotherapy. Targeted therapy which specifically inhibits molecular abnormalities has emerged as a novel approach for the innovative and effective medical treatment of malignancies. In order to fulfill this promise there is an urgent need to identify the optimal targets for the treatment of HCC. A multi-kinase angiogenesis inhibitor, sorafenib, has been revealed as the first agent to show favorable overall survival in patients with advanced HCC. A new era of HCC treatment has arrived, but there has been limited improvement in survival benefits with the status quo. This review summarizes molecular targeted therapy for HCC, with a focus on angiogenesis, growth signaling, and mitosis, as well as a promising concept, "cancer stemness" for the current and potential next strategies of HCC treatment.

Angiopoietin-2 serum levels are elevated in patients with liver cirrhosis and hepatocellular carcinoma

OBJECTIVES

Liver cirrhosis is characterized by remodeling leading to nodules that are difficult to discern from hepatocellular carcinoma (HCC). Alpha-fetoprotein (AFP) serum levels are used for the screening for HCC, with limited success. We evaluated angiopoietin-2 as a serum marker in patients with cirrhosis and with HCC.

METHODS

In a retrospective study, we measured angiopoietin-2 serum levels in 131 patients with HCC, 180 patients with cirrhosis, and 40 healthy controls. We also determined AFP serum levels in patients with HCC and compared the test characteristics of both serum markers. The expression patterns of angiopoietin-2 were determined by in situ hybridization in healthy and cirrhotic livers as well as in HCC.

RESULTS

Angiopoietin-2 serum levels were elevated in patients with liver cirrhosis (P < 0.0001) compared with healthy controls. Levels were further elevated in patients with HCC compared with healthy controls (P < 0.0001) and cirrhotic patients (P < 0.0001). The combination with AFP measurements led to improved discrimination between HCC and cirrhosis. Angiopoietin-2 message was present in tumor cells of HCCs but was absent from hepatocytes of cirrhotic and healthy livers. In cirrhosis, message was detected within the strands of fibrous tissue.

CONCLUSIONS

Serum angiopoietin-2 levels are elevated in patients with cirrhosis, implicating a possible role of the angiopoietin-Tie-2 system for neoangiogenesis in cirrhosis. Serum levels are further elevated in patients with HCC, suggesting the potential use of angiopoietin-2 as a marker for the detection of cirrhosis and HCC.

Co-carcinogenic effect of cyclohexanol on the development of preneoplastic lesions in a rat hepatocarcinogenesis model

Cyclohexanol is a basic industrial chemical widely used because of its versatility as an industrial solvent. No studies have been conducted to evaluate the carcinogenic/co-carcinogenic hazards associated with cyclohexanol exposure. In male Fisher 344 rats liver preneoplastic lesions were induced by N-nitrosodiethylamine (150 mg/Kg) i.p., followed by the tumor promoter 2-acetylaminofluorene (2-AAF: 20 mg/kg) orally administered on three consecutive days before partial hepatectomy. The cyclohexanol administration in this hepatocarcinogenesis assay revealed that it has a strong tumor co-promoter potential. There is clear evidence that oxidative stress and the CYP2E1 are components of carcinogenesis. Although no changes in the lipid peroxidation levels were observed between treated and untreated animals, a significant increase in CYP2E1 expression was observed when cyclohexanol was administered 24 h after the last 2-AAF dose. On the other hand, levels of the proliferation markers PCNA and Ki-67 were not increased after treatment with cyclohexanol, but a marked downregulation of the Bax proapoptotic protein was found exclusively in mitochondrial extracts of animals treated with cyclohexanol. This study represents the first report of the ability of cyclohexanol-induced lesions, when administered simultaneously with 2-AAF, to potentiate the development of preneoplastic liver.

Hepatitis B virus promotes angiopoietin-2 expression in liver tissue: role of HBV x protein

The progression of chronic hepatitis B (CHB) is related to fibrosis and to the emergence of intrahepatic anomalous vascular structures. Hepatitis B virus (HBV) X protein transactivator (HBx) may play a significant role in both processes. To analyze how HBV induces vascular growth and remodeling in vivo, we assessed the expression of angiopoietin-2 (Ang2) in liver biopsies from CHB patients by reverse transcriptase-polymerase chain reaction, Western blotting, and immunohistochemistry because of the relevant role of Ang2 in vascular development, remodeling, and tumor promotion. In addition, we analyzed the influence of HBx in the expression of Ang2 in HBx-expressing hepatocyte cell lines and in hepatic stellate cells stimulated with conditional medium from HBx-hepatocytes. Ang2 expression was clearly up-regulated at both mRNA and protein levels in the liver of CHB patients, showing an intense staining of inflammatory infiltrates and vascular structures at inflamed portal areas. HBx-expressing hepatocytes and stimulated stellate cells showed a significant induction of Ang2 expression. PI3K inhibitor and antioxidants repressed the 64-kd Ang2 form but further enhanced the inflammation-related 50-kd molecular species. Therefore, HBx could account for the induction of Ang2 observed in CHB, especially the 50-kd form, contributing to pathological angiogenesis and hepatocellular carcinoma progression.

Current status and perspective of antiangiogenic therapy for cancer: hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is well known as a typical angiogenic tumor, especially in the moderately to poorly differentiated type. Such clinicopathological characteristics are not only useful for imaging diagnosis but are also applicable to the treatment of HCC. In addition, recent molecular studies have revealed that angiogenesis is closely related to hepatocarcinogenesis. In this review, the molecular mechanism of HCC angiogenesis and the antiangiogenic prevention of HCC are reviewed to introduce the latest trends in antiangiogenic treatment of cancers, including HCC.