Review of angiogenesis in hepatocellular carcinoma

Cross-talk mechanism between endothelial cells and hepatocellular carcinoma cells via growth factors and integrin pathway promotes tumor angiogenesis and cell migration

Tumor angiogenesis plays a central role in the development and metastasis of hepatocellular carcinoma. Cancer cells secrete angiogenic factors to recruit vascular endothelial cells and sustain tumor vascular networks, which facilitate the migration and invasion of cancer cells. Therefore, the cross-talk between vascular endothelial cells and cancer cells is vitally necessary, however, little is known about the cross-talk mechanism of these cells interaction. In the present study, the proliferation, migration, invasion and tube formation of vascular endothelial EA.hy926 cells and hepatocellular carcinoma HepG2 cells were studied by exchanging their culture medium. The time-dependent differences of integrins induced signaling pathway associated with cell migration were investigated. Our results showed that HepG2 cells markedly enhanced the proliferation and migration ability as well as the tube formation of EA.hy926 cells by releasing growth factors. Also, the EA.hy926 cells promoted the proliferation, migration and invasion ability of HepG2 cells. The further analysis demonstrated that the integrins-FAK-Rho GTPases signaling events in both of two cells was activated under conditioned medium, and the signaling molecules in two cell lines showed a different time-dependent expression within 1h. These findings reveal the cross-talk mechanism between the endothelial cells and hepatocellular carcinoma cells, which were expected to find out new ideas for the prevention and treatment of hepatocellular carcinoma.

Immunohistochemical angiogenic biomarkers in hepatocellular carcinoma and cirrhosis: correlation with pathological features

OBJECTIVE

To investigate immunohistochemical markers of angiogenesis and their association with pathological prognostic features in hepatocellular carcinoma and cirrhotic liver.

METHODS

Vascular endothelial growth factor, CD105, and cyclooxygenase-2 were immunohistochemically detected in 52 hepatocellular carcinoma tissue samples and 48 cirrhotic liver tissue samples. Semiquantitative measurements of vascular endothelial growth factor and cyclooxygenase-2 were evaluated considering the degree and intensity of immunostaining based on a 7-point final scoring scale. CD105 microvascular density (MVD-CD105) was measured using automated analysis. Morphological aspects evaluated in the hepatocellular carcinoma samples included size (≤2 and >2 cm), differentiation grade, and microvascular invasion.

RESULTS

The mean vascular endothelial growth factor immunoreactivity score was slightly higher in the hepatocellular carcinoma samples (4.83±1.35) than the cirrhotic liver (4.38±1.28) samples. There was a significant and direct correlation between these mean scores (rs=0.645, p=0.0001). Cyclooxygenase-2 was expressed in all the cirrhotic liver samples but was only found in 78% of the hepatocellular carcinoma samples. The mean cyclooxygenase-2 score was higher in the cirrhotic liver samples (4.85±1.38) than the hepatocellular carcinoma samples (2.58±1.68), but there was no correlation between the scores (rs=0.177, p=0.23). The mean CD105 percentage in the hepatocellular carcinoma samples (11.2%) was lower than that in the cirrhotic samples (16.9%). There was an inverse relationship in MVD-CD105 expression between the hepatocellular carcinoma and cirrhotic samples (rs=-0.78, p=0.67). There were no significant associations between vascular endothelial growth factor expression and morphological characteristics. Cyclooxygenase-2 and CD105 were associated with hepatocellular carcinoma differentiation grade (p=0.003 and p=0.05, respectively).

CONCLUSION

Vascular endothelial growth factor, cyclooxygenase-2, and MVD-CD105 were highly expressed in cirrhotic liver compared to hepatocellular carcinoma and might be involved in liver carcinogenesis. Additionally, cyclooxygenase-2 and CD105 might be involved in hepatocellular carcinoma differentiation grade.

Roles and Signaling Pathways of Des-γ-Carboxyprothrombin in the Progression of Hepatocellular Carcinoma

Des-γ-carboxyprothrombin (DCP), an abnormal prothrombin produced in human hepatocellular carcinoma (HCC), plays crucial roles in the progression of HCC. DCP binding to cellular mesenchymal-epithelial transition factor (c-Met) is an initial event and consequently stimulates HCC through the increase of c-Met-Janus kinase 1- signal transducers and activators of transcription pathways. DCP stimulates HCC invasion through activation of matrix metalloproteinase via upregulation of extracellular signal-regulated kinase-mitogen-activated protein kinase (MAPK) pathway. DCP stimulates HCC angiogenesis through activation of the DCP-kinase insert domain receptor-phospholipaseC-γ-MAPK pathway. Identification of these pathways is important for designing the therapeutic strategy for HCC.

Intravoxel incoherent motion diffusion-weighted imaging for characterizing focal hepatic lesions: Correlation with lesion enhancement

PURPOSE

To evaluate the value of intravoxel incoherent motion (IVIM) parameters for characterizing focal hepatic lesions, and to assess the correlation between IVIM parameters and arterial nodule enhancement.

MATERIALS AND METHODS

We retrospectively evaluated 161 lesions (91 hepatocellular carcinomas [HCCs], 27 intrahepatic cholangiocarcinomas [IHCCs], 20 hemangiomas, 9 combined hepatocellular-cholangiocarcinomas, 9 metastases, and 5 other tumors) in 161 patients (105 men and 56 women; mean age, 56.4 years). Diffusion-weighted imaging was performed using nine b-values (0-900 s/mm² ) at 1.5T. Apparent diffusion coefficient (ADC), molecular diffusion coefficient (D_slow ), perfusion fraction (f), and perfusion-related diffusion coefficient (D_fast ) were compared among the hepatic lesions using analysis of variance (ANOVA). Receiver-operating-characteristic analysis was performed to assess diagnostic performance. The enhancement fraction (EF) and the relative enhancement (RE) of the hepatic lesions on arterial phase gadoxetic acid-enhanced images were correlated with the IVIM parameters using Spearman's test.

RESULTS

For the differentiation of hemangiomas from malignant tumors, D_slow showed the largest area under the curve (0.933) among all parameters. Although ADC did not show any difference among malignant lesions (P ≥ 0.28), HCCs showed a significantly lower D_slow than IHCC (P < 0.001) and a higher f than did IHCC (P < 0.001) and metastasis (P = 0.027); f had a significant positive correlation with EF (r = 0.420, P < 0.001) and RE (r = 0.264, P = 0.001).

CONCLUSION

IVIM parameters are more helpful in characterizing malignant hepatic lesions than ADC; f may reflect the extent and degree of hepatic nodule enhancement in the arterial phase, and may allow for differentiation of HCC from IHCC and metastasis.

LEVEL OF EVIDENCE

3 J. MAGN. RESON. IMAGING 2017;45:1589-1598.

Inhibition of VEGF165/VEGFR2-dependent signaling by LECT2 suppresses hepatocellular carcinoma angiogenesis

Hepatocellular carcinoma (HCC) relies on angiogenesis for growth and metastasis. Leukocyte cell-derived chemotaxin 2 (LECT2) is a cytokine and preferentially expressed in the liver. Previous studies have found that LECT2 targets to both immune and tumor cells to suppress HCC development and vascular invasion. Although LECT2 did not affect HCC cells growth in vitro, it still suppressed HCC xenografts growth in immune-deficient mice, suggesting other cells such as stroma cells may also be targeted by LECT2. Here, we sought to determine the role of LECT2 in tumor angiogenesis in HCC patients. We found that LECT2 expression inhibited tumor growth via angiogenesis in the HCC xenograft model. Specifically, we demonstrated that recombinant human LECT2 protein selectively suppressed vascular endothelial growth factor (VEGF)₁₆₅-induced endothelial cell proliferation, migration, and tube formation in vitro and in vivo. Mechanistically, LECT2 reduced VEGF receptor 2 tyrosine phosphorylation and its downstream extracellular signal-regulated kinase and AKT phosphorylation. Furthermore, LECT2 gene expression correlated negatively with angiogenesis in HCC patients. Taken together, our findings demonstrate that LECT2 inhibits VEGF₁₆₅-induced HCC angiogenesis through directly binding to VEGFR2 and has broad applications in treating VEGF-mediated solid tumors.

Candesartan attenuates angiogenesis in hepatocellular carcinoma via downregulating AT1R/VEGF pathway

Angiotensin II type 1 receptor (AT1R) was reported to express in many types of tumors, promoting tumor growth and angiogenesis. We herein examined AT1R expression in liver cancer and the potential antitumor effects of AT1R antagonist Candesartan in liver cancer. We found that AT1R expression was positively correlated with VEGF-A expression and microvascular density (MVD) in 40 HCC patients. Angiotensin II and Candesartan neither had effects on the proliferation of liver cancer cells in vitro. However, Angiotensin II upregulated AT1R protein expression and promoted production of VEGF-A in liver cancer cells in a dose-dependent manner. Candesartan was able to reverse this process in a dose-dependent manner. Moreover, Candesartan downregulated the expression of VEGF-A in SMMC-7721 bearing xenografts in mice and inhibited tumor growth and angiogenesis in vivo. Our data suggested that AT1R antagonist Candesartan might be useful to suppress liver cancer by inhibiting angiogenesis.

Gastric tumour-derived ANGPT2 regulation by DARPP-32 promotes angiogenesis

OBJECTIVE

Overexpression of dopamine and cAMP-regulated phosphoprotein, Mr 32000 (DARPP-32), and its truncated isoform (t-DARPP) are associated with gastric tumorigenesis. Herein, we investigated the role of DARPP-32 proteins in regulating angiopoietin 2 (ANGPT2) and promoting tumour angiogenesis.

DESIGN

Quantitative real-time RT-PCR, immunoblotting, luciferase reporter, immunofluorescence, immunohistochemistry and angiogenesis assays were applied to investigate the regulation of angiogenesis by DARPP-32 proteins.

RESULTS

Overexpression of DARPP-32 significantly increased the mRNA and protein levels of ANGPT2 in gastric cancer cells. The overexpression of DARPP-32 T34A mutant or the N-terminal truncated isoform, t-DARPP, led to similar effects ruling out the T34-dependent regulation of protein phosphatase 1 activity in regulating ANGPT2. DARPP-32 proteins induced a secreted form of ANGPT2, which was detectable in the media, functionally active, and able to induce angiogenesis, measured by the human umbilical vein endothelial cells tube formation assay. Antibody blocking of the secreted ANGPT2 abrogated its function. To identify the mechanism by which DARPP-32 regulates ANGPT2, we examined the activities of NF-κB and signal transducer and activator of transcription 3 (STAT3), known regulators of angiogenesis. The results ruled out NF-κB and showed induction of STAT3 phosphorylation, activation and nuclear localisation. Inhibition or knockdown of STAT3 significantly attenuated the induction of ANGPT2 by DARPP-32 proteins. In vivo xenograft models demonstrated that overexpression of DARPP-32 promotes angiogenesis and tumour growth. Analyses of human gastric cancer tissues showed a strong correlation between DARPP-32 and ANGPT2.

CONCLUSIONS

Our novel findings establish the role of DARPP-32-STAT3 axis in regulating ANGPT2 in cancer cells to promote angiogenesis and tumorigenesis.

In vitro and in vivo study of hydralazine, a potential anti-angiogenic agent

Hydralazine (HYD), an old routine clinical anti-hypertension drug, is rarely used in clinic nowadays. Since the strategy of repositioning old drugs was put forward, HYD has been reported to possess various biological activities, including antitumor efficacy and reducing intra-tumor microvessel. Here, we investigated that whether HYD had the ability of anti-angiogeneis and its underlying mechanism. Cells proliferation, wound-healing, Transwell migration and invasion, tube formation and rat aortic ring assays in vitro and chicken chorioallantoic membrane (CAM) model in vivo were designed to investigated HYD's anti-angiogenic effect. Levels of vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) were assessed by enzyme-linked immune sorbent assay (ELISA). Hepatocellular carcinoma (HCC) mice model was used to evaluate HYD's effect on tumor growth and microvessel density. Our results showed that HYD not only inhibited human umbilical vascular endothelial cell (HUVEC) proliferation, wound-healing, Transwell migration and invasion and tube formation, but also suppressed the microvessel outgrowth of rat aortic ring in vitro and the neovascularzation of CAM in vivo. Furthermore, we demonstrated that HYD attenuated tumor angiogenesis and tumor growth. In the co-culture system of Transwell migration, the secretion of VEGF and bFGF was reduced by HYD respectively. In sum, our data indicate that HYD has the pharmacological effect of ant-angiogenesis by interference with VEGF and bFGF signaling pathways in endothelial cells. These findings suggest that HYD might be a promising angiogenesis inhibitor and a potential effective therapeutic agent for cancer therapy.

Molecular pathogenesis of hepatocellular carcinoma and impact of therapeutic advances

Hepatocellular carcinoma (HCC) is a leading cause of cancer mortality and has an increasing incidence worldwide. HCC can be induced by multiple etiologies, is influenced by many risk factors, and has a complex pathogenesis. Furthermore, HCCs exhibit substantial heterogeneity, which compounds the difficulties in developing effective therapies against this highly lethal cancer. With advances in cancer biology and molecular and genetic profiling, a number of different mechanisms involved in the development and progression of HCC have been identified. Despite the advances in this area, the molecular pathogenesis of hepatocellular carcinoma is still not completely understood. This review aims to elaborate our current understanding of the most relevant genetic alterations and molecular pathways involved in the development and progression of HCC, and anticipate the potential impact of future advances on therapeutic drug development.

A small interfering RNA targeting vascular endothelial growth factor efficiently inhibits growth of VX2 cells and VX2 tumor model of hepatocellular carcinoma in rabbit by transarterial embolization-mediated siRNA delivery

Introduction

Hepatocellular carcinoma is currently the second leading cause of cancer-related deaths worldwide with an increasing incidence.

Objective

The objective of this study is to investigate the effect of vascular endothelial growth factor small interfering RNA (VEGF-siRNA) on rabbit VX2 carcinoma cell viability in vitro and the effect of transarterial embolization (TAE)-mediated VEGF-siRNA delivery on the growth of rabbit VX2 liver-transplanted model in vivo.

Methods

Quantitative reverse transcription polymerase chain reaction, enzyme-linked immunosorbent assay, and Western blot technologies were used to detect the expression level of VEGF. TAE and computed tomography scan were used to deliver the VEGF-siRNA and detect the tumor volume in vivo, respectively. Microvessel density was detected by immunohistochemistry with CD34 antibody. A biochemical autoanalyzer was used to evaluate the hepatic and renal toxicity.

Results

The designed VEGF-siRNAs could effectively decrease the expression levels of VEGF mRNA and protein in vitro and in vivo. In vitro, the viability of rabbit VX2 carcinoma cells was reduced by 38.5%±7.3% (VEGF-siRNA no 1) and 30.0%±5.8% (VEGF-siRNA no 3) at 48 hours after transfection. Moreover, in rabbit VX2 liver-transplanted model, the growth ratios of tumors at 28 days after TAE-mediated siRNA delivery were 155.18%±19.42% in the control group, 79.67%±19.63% in the low-dose group, and 36.09%±15.73% in the high-dose group, with significant differences among these three groups. Microvessel density dropped to 34.22±4.01 and 22.63±4.07 in the low-dose group and high-dose group, respectively, compared with the control group (57.88±5.67), with significant differences among these three groups. Furthermore, inoculation of VX2 tumor into the liver itself at later stage induced significant increase in alanine aminotransferase and aspartate aminotransferase, indicating an obvious damage of liver functions, while treatment of VX2 tumor via TAE-mediated VEGF-siRNA had no toxicity to the livers and kidneys of rabbits, and VEGF-siRNA had the ability to protect liver damage induced by tumor growth.

Conclusion

This is the first study to demonstrate that targeting VEGF via TAE-mediated siRNA delivery may become a powerful new option for effective treatment of hepatocellular carcinoma in the clinic.

Diagnostic accuracy of diffusion-weighted magnetic resonance imaging versus positron emission tomography/computed tomography for early response assessment of liver metastases to Y90-radioembolization

Objectives

Patients with hepatic metastases who are candidates for Y90-radioembolization (Y90-RE) usually have advanced tumor stages with involvement of both liver lobes. Per current guidelines, these patients have usually undergone several cycles of potentially hepatotoxic systemic chemotherapy before Y90-RE is at all considered, requiring split (lobar) treatment sessions to reduce hepatic toxicity. Assessing response to Y90-RE early, that is, already after the first lobar session, would be helpful to avoid an ineffective and potentially hepatotoxic second lobar treatment. We investigated the accuracy with which diffusion- weighted magnetic resonance imaging (DWI-MRI) and positron emission tomography/computed tomography (PET/CT) can provide this information.

Methods

An institutional review board–approved prospective intraindividual comparison trial on 35 patients who underwent fluorodeoxyglucose PET/CT and DWI-MRI within 6 weeks before and 6 weeks after Y90-RE to treat secondary-progressive liver metastases from solid cancers (20 colorectal, 13 breast, 2 other) was performed. An increase of minimal apparent diffusion coefficient (ADCmin) or decrease of maximum standard uptake value (SUVmax) by at least 30% was regarded as positive response. Long-term clinical and imaging follow-up was used to distinguish true- from false-response classifications.

Results

On the basis of long-term follow-up, 23 (66%) of 35 patients responded to the Y90 treatment. No significant changes of metastases size or contrast enhancement were observable on pretreatment versus posttreatment CT or magnetic resonance images.However, overall SUVmax decreased from 8.0 ± 3.9 to 5.5 ± 2.2 (P < 0.0001), and ADCmin increased from 0.53 ± 0.13 × 10⁻³ mm²/s to 0.77 ± 0.26 × 10⁻³ mm²/s (P < 0.0001). Pretherapeutic versus posttherapeutic changes of ADCmin and SUVmax correlated moderately (r = −0.53). In 4 of the 35 patients (11%), metastases were fluorodeoxyglucose-negative such that no response assessment was possible by PET. In 25 (71%) of the 35 patients, response classification by PET and DWI-MRI was concordant; in 6 (17%) of the 35, it was discordant. In 5 of the 6 patients with discordant classifications, follow-up confirmed diagnoses made by DWI. The positive predictive value to predict response was 22 (96%) of 23 for MRI and 15 (88%) of 17 for PET. The negative predictive value to predict absence was 11 (92%) of 12 for MRI and 10 (56%) of 18 for PET. Sensitivity for detecting response was significantly higher for MRI (96%; 22/23) than for PET (65%; 15/23) (P < 0.02).

Conclusions

Diffusion-weighted magnetic resonance imaging appears superior to PET/CT for early response assessment in patients with hepatic metastases of common solid tumors. It may be used in between lobar treatment sessions to guide further management of patients who undergo Y90-RE for hepatic metastases.

AGK enhances angiogenesis and inhibits apoptosis via activation of the NF-κB signaling pathway in hepatocellular carcinoma

High levels of angiogenesis and resistance to apoptosis are major clinical features of hepatocellular carcinoma (HCC), a lethal disease with a high incidence worldwide. However, the precise mechanisms underlying these malignant properties remain unclear. Here, we demonstrated that acylglycerol kinase (AGK) is markedly overexpressed in HCC cell lines and clinical tissues. Immunohistochemical analysis of 245 clinical HCC specimens revealed patients with high levels of AGK expression had poorer overall survival compared to patients with low AGK expression. Furthermore, overexpressing AGK significantly enhanced angiogenesis and inhibited apoptosis in vitro and promoted the tumorigenicity of HCC cells in vivo; silencing endogenous AGK had the opposite effects. Importantly, AGK enhanced angiogenesis and inhibited apoptosis in HCC in part via activation of NF-κB signaling. Our findings provide new evidence that AGK plays an important role in promoting angiogenesis and providing resistance to apoptosis, thus AGK may represent a novel therapeutic target for HCC.

Facing the enigma of the vascular network in hepatocellular carcinomas in cirrhotic and non-cirrhotic livers

AIMS

In this paper we aimed to analyse the typology and the phenotype of the different vascular modifications in human hepatocellular carcinomas (HCCs) with a new immunomorphological and gene expression approach. We also attempted to correlate these modifications with the histological parameters of tumour aggressiveness and the surrounding liver parenchyma.

METHODS

Ninety-six HCCs (from 80 patients) were retrospectively enrolled, 46 occurring in non-cirrhotic livers, and 50 in livers transplanted for cirrhosis. Histopathological analysis, immunohistochemistry for CD34, Nestin and WT1 and RT-PCR for Nestin, transforming growth factor-β1 (TGFβ1) and insulin-like growth factor 1 (IGF1R) mRNA were performed in all nodules.

RESULTS

By correlating the CD34 and Nestin immunoreactivity in HCC vasculature with the tumorous architecture, we identified four vascular patterns (named from 'a' to 'd'). Each of them was characterised by different expressions of TGFβ1 and IGF1R mRNA. Pattern a showed CD34-positive/Nestin-negative sinusoids, and was prevalent in microtrabecular lesions. Pattern b showed similar morphology and architecture as pattern a, but with Nestin-positive sinusoids and a significant 'boost' in IGF1R and TGFβ1 mRNAs. In patterns c and d a progressive sinusoid loss and a gain of newly formed arterioles were seen. Notably, HCCs with pattern a arose more frequently in cirrhosis (p=0.024), and showed lower incidence of microvascular invasion (p=0.002) and infiltration (p=0.005) compared with HCCs with other patterns.

CONCLUSIONS

Although future studies are surely required, the identification of different vascular profiles in HCCs from cirrhotic and non-cirrhotic livers may help clarify the relationship between HCC progression and aggressiveness.

Overexpression of AGGF1 is correlated with angiogenesis and poor prognosis of hepatocellular carcinoma

Angiogenic factor with G-patch and FHA domains 1 (AGGF1) is a factor implicating in vascular differentiation and angiogenesis. Several lines of evidence indicate that aberrant expression of AGGF1 is associated with tumor initiation and progression. The aim of this study was to investigate the expression and prognostic value of AGGF1 in hepatocellular carcinoma (HCC), as well as its relationship with clinicopathological factors and tumor angiogenesis. Immunohistochemistry was performed to evaluate the expression of AGGF1 in HCC and paracarcinomatous tissues collected from 70 patients. Vascular endothelial growth factor (VEGF) and CD34 expression levels were examined in the 70 HCC tissues. Prognostic significance of tumoral AGGF1 expression was determined. Notably, AGGF1 expression was significantly higher in HCC than in surrounding non-tumor tissues (65.7 vs. 25.7 %; P < 0.001). AGGF1 expression was significantly correlated with tumoral VEGF expression and CD34-positive microvessel density. Moreover, AGGF1 expression was significantly associated with tumor size, tumor capsule, vascular invasion, Edmondson grade, alpha-fetoprotein level, and TNM stage. Kaplan-Meier survival analysis showed that high AGGF1 was correlated with reduced overall survival (OS) rate (P = 0.001) and disease-free survival (DFS) rate (P < 0.001). Multivariate analysis identified AGGF1 as an independent poor prognostic factor of OS and DFS in HCC patients (P = 0.043 and P = 0.010, respectively). Taken together, increased AGGF1 expression is associated with tumor angiogenesis and serves as an independent unfavorable prognostic factor for OS and DFS in HCC. AGGF1 may represent a potential therapeutic target for HCC.

Heterogeneity of hepatocellular carcinoma contributes to cancer progression

Hepatocellular carcinoma (HCC) is a highly heterogeneous disease displaying differences in angiogenesis, extracellular matrix proteins, the immune microenvironment and tumor cell populations. Additionally, genetic variations and epigenetic changes of HCC cells could lead to aberrant signaling pathways, induce cancer stem cells and enhance tumor progression. Thus, the heterogeneity in HCC contributes to disease progression and a better understanding of its heterogeneity will greatly aid in the development of strategies for the HCC treatment.