Overexpression of angiopoietin-1 and angiopoietin-2 in hepatocellular carcinoma

The role of liver sinusoidal endothelial cells in metabolic dysfunction-associated steatotic liver diseases and liver cancer: mechanisms and potential therapies

Liver sinusoidal endothelial cells (LSECs), with their unique morphology and function, have garnered increasing attention in chronic liver disease research. This review summarizes the critical roles of LSECs under physiological conditions and in two representative chronic liver diseases: metabolic dysfunction-associated steatotic liver disease (MASLD) and liver cancer. Under physiological conditions, LSECs act as selective barriers, regulating substance exchange and hepatic blood flow. Interestingly, LSECs exhibit contrasting roles at different stages of disease progression: in the early stages, they actively resist disease advancement and help restore sinusoidal homeostasis; whereas in later stages, they contribute to disease worsening. During this transition, LSECs undergo capillarization, lose their characteristic markers, and become dysfunctional. As the disease progresses, LSECs closely interact with hepatocytes, hepatic stellate cells, various immune cells, and tumor cells, driving processes such as steatosis, inflammation, fibrosis, angiogenesis, and carcinogenesis. Consequently, targeting LSECs represents a promising therapeutic strategy for chronic liver diseases. Relevant therapeutic targets and potential drugs are summarized in this review.

Unveiling novel serum biomarkers in intrahepatic cholangiocarcinoma: a pilot proteomic exploration

Recent advancements in proteomics have shown promise in identifying biomarkers for various cancers. Our study is the first to compare the serum proteomes of intrahepatic cholangiocarcinoma (iCCA) with cirrhosis (CIR), primary sclerosing cholangitis (PSC), and hepatocellular carcinoma (HCC), aiming to identify a proteomic signature that can effectively distinguish among these conditions. Utilizing high-throughput mass spectrometry on serum samples, we identified 845 proteins, of which 646 were suitable for further analysis. Unique clustering patterns were observed among the five groups, with significant proteomic differences. Our key findings include: S100 calcium-binding protein A9 (S100A9) and haptoglobin (HP) were more abundant in iCCA, while intercellular adhesion molecule 2 (ICAM2) was higher in HCC. Serum amyloid A1 (SAA1) and A4 (SAA4) emerged as potential biomarkers, with SAA1 significantly different in the iCCA vs healthy controls (HC) comparison, and SAA4 in the HCC vs HC comparison. Elevated levels of vascular cell adhesion molecule 1 (VCAM-1) in HCC suggested its potential as a differentiation and diagnostic marker. Angiopoietin-1 receptor (TEK) also showed discriminatory and diagnostic potential in HCC. ELISA validation corroborated mass spectrometry findings. Our study underscores the potential of proteomic profiling in distinguishing iCCA from other liver conditions and highlights the need for further validation to establish robust diagnostic biomarkers.

New Opportunities in the Systemic Treatment of Hepatocellular Carcinoma-Today and Tomorrow

Hepatocellular carcinoma (HCC) is the most common primary liver cancer. Liver cirrhosis, hepatitis B, hepatitis C, and non-alcoholic fatty liver disease represent major risk factors of HCC. Multiple different treatment options are available, depending on the Barcelona Clinic Liver Cancer (BCLC) algorithm. Systemic treatment is reserved for certain patients in stages B and C, who will not benefit from regional treatment methods. In the last fifteen years, the arsenal of available therapeutics has largely expanded, which improved treatment outcomes. Nevertheless, not all patients respond to these agents and novel combinations and drugs are needed. In this review, we aim to summarize the pathway of trials investigating the safety and efficacy of targeted therapeutics and immunotherapies since the introduction of sorafenib. Furthermore, we discuss the current evidence regarding resistance mechanisms and potential novel targets in the treatment of advanced HCC.

Overview of hepatocellular carcinoma: from molecular aspects to future therapeutic options

Hepatocellular carcinoma (HCC) is the seventh most highly prevalent malignant tumor globally and the second most common cause of mortality. HCC develops with complex pathways that occur through multistage biological processes. Non-alcoholic fatty liver disease, metabolic-associated fatty liver disease, alcoholic liver disease, autoimmune hepatitis, hepatitis B, and hepatitis C are the causative etiologies of HCC. HCC develops as a result of epigenetic changes, protein-coding gene mutations, and altered signaling pathways. Biomarkers and potential therapeutic targets for HCC open up new possibilities for treating the disease. Immune checkpoint inhibitors are included in the treatment options in combination with molecular targeted therapy.

Intracellular angiopoietin-1 promotes TKI-resistance via activation of JAK/STAT5 pathway in chronic myeloid leukemia

Drug resistance from BCR-ABL tyrosine kinase inhibitors (TKIs) and other chemotherapeutics results in treatment failure and disease progression in chronic myeloid leukemia (CML). However, the mechanism is still uncertain. In this study, we investigated the role of angiopoietin-1 (ANG-1) as a potential prognostic factor for drug resistance in CML. Both intracellular and secretory ANG-1 (iANG-1 and sANG-1) were overexpressed in multidrug-resistant CML samples. The IC₅₀ value was higher in primary CD34⁺ CD38^- cells with more ANG-1. Silencing ANG-1significantly sensitized three TKI-resistant CML cell lines to imatinib (IM) while recombinant human ANG-1 failed to retain cell survival in vitro. This indicated the important role of iANG-1 as opposed to sANG-1 in CML drug resistance. Moreover, a similar effect was observed in xenograft mice models bearing ANG-1-silenced CML cells. Subsequently, pathway analysis and protein validation experiments showed activation of the JAK/STAT pathway and augmentation of STAT5a phosphorylation in ANG-1 restored CML cells. Upstream Src phosphorylation, which plays a crucial role in CML drug resistance, was also upregulated as a key event in iANG-1-related JAK/STAT pathway activation. In conclusion, our study elucidated a new BCR-ABL independent molecular mechanism induced by intracytoplasmic ANG-1 overexpression as a potential strategy for overcoming CML resistance.

Mechanism of paracrine communications between hepatic progenitor cells and endothelial cells

Hepatic progenitor cells (HPCs) are facultative tissue-specific stem cells lining reactive ductules, which are ubiquitously observed in chronic liver diseases and cancer. Although previous research mainly focused on their contribution to liver regeneration, it turned out that in vivo differentiation of HPCs into hepatocytes only occurs after extreme injury. While recent correlative evidence implies the association of HPCs with disease progression, their exact role in pathogenesis remains largely unknown. Our previous research demonstrated that HPCs expressing angiogenic paracrine factors accumulate in the peritumoral area and are positively correlated with the extent of intratumoral cell proliferation and angiogenesis in the livers of patients with liver cancer. Given the crucial roles of angiogenesis in liver disease progression and carcinogenesis, we aimed to test the hypothesis that HPCs secrete paracrine factors to communicate with endothelial cells, to determine molecular mechanisms mediating HPCs-endothelial interactions, and to understand how the paracrine function of HPCs is regulated. HPCs promoted viability and tubulogenesis of human umbilical vein endothelial cells (HUVECs) and upregulated genes known to be involved in angiogenesis, endothelial cell function, and disease progression in a paracrine manner. The paracrine function of HPCs as well as expression of colony stimulating factor 1 (CSF1) were inhibited upon differentiation of HPCs toward hepatocytes. Inhibition of CSF1 receptor partly suppressed the paracrine effects of HPCs on HUVECs. Taken together, our study indicates that inhibition of the paracrine function of HPCs through modulation of their differentiation status and inhibition of CSF1 signaling is a promising strategy for inhibition of angiogenesis during pathological progression.

SGLT-2 Inhibitors in Cancer Treatment-Mechanisms of Action and Emerging New Perspectives

A new group of antidiabetic drugs, sodium-glucose cotransporter 2 inhibitors (SGLT-2 inhibitors), have recently been shown to have anticancer effects and their expression has been confirmed in many cancer cell lines. Given the metabolic reprogramming of these cells in a glucose-based model, the ability of SGLT-2 inhibitors to block the glucose uptake by cancer cells appears to be an attractive therapeutic approach. In addition to tumour cells, SGLT-2s are only found in the proximal tubules in the kidneys. Furthermore, as numerous clinical trials have shown, the use of SGLT-2 inhibitors is well-tolerated and safe in patients with diabetes and/or heart failure. In vitro cell culture studies and preclinical in vivo studies have confirmed that SGLT-2 inhibitors exhibit antiproliferative effects on certain types of cancer. However, the mechanisms of this action remain unclear. Even in those tumour cell types in which SGLT-2 is present, there is sometimes an SGLT-2-independent mechanism of anticancer action of this group of drugs. This article presents the current state of knowledge of the potential mechanisms of the anticancer action of SGLT-2 inhibitors and their possible future application in clinical oncology.

The clinical value of angiopoietin-2 in liver diseases

Content available: Audio Recording.

Early Predictive Value of Circulating Biomarkers for Sorafenib in Advanced Hepatocellular Carcinoma

INTRODUCTION

Sorafenib is currently the first-line therapeutic regimen for patients with advanced hepatocellular carcinoma (HCC). However, many patients did not experience any benefit and suffered extreme adverse events and heavy economic burden. Thus, the early identification of patients who are most likely to benefit from sorafenib is needed.

AREAS COVERED

This review focused on the clinical application of circulating biomarkers (including conventional biomarkers, immune biomarkers, genetic biomarkers, and some novel biomarkers) in advanced HCC patients treated with sorafenib. An online search on PubMed, Web of Science, Embase, and Cochrane Library was conducted from the inception to Aug 15, 2021. Studies investigating the predictive or prognostic value of these biomarkers were included.

EXPERT OPINION

The distinction of patients who may benefit from sorafenib treatment is of utmost importance. The predictive roles of circulating biomarkers could solve this problem. Many biomarkers can be obtained by liquid biopsy, which is a less or non-invasive approach. The short half-life of sorafenib could reflect the dynamic changes of tumor progression and monitor the treatment response. Circulating biomarkers obtained from liquid biopsy resulted as a promising assessment method in HCC, allowing for better treatment decisions in the near future.

Hepatocellular Carcinoma: Molecular Pathogenesis and Therapeutic Advances

Hepatocellular carcinoma (HCC), the most common form of liver cancer, continues to be a serious medical problem with poor prognosis, without major therapeutic improvement for years and increasing incidence. Fortunately, advances in systemic treatment options are finally arriving for HCC patients. After a decade of sorafenib as a standard therapy for advanced HCC, several tyrosine kinase inhibitors (TKIs), antiangiogenic antibodies, and immune checkpoint inhibitors have reached the clinic. Although infections by hepatitis B virus and hepatitis C virus remain principal factors for HCC development, the rise of non- alcoholic steatohepatitis from diabetes mellitus or metabolic syndrome is impeding HCC decline. Knowledge of specific molecular mechanisms, based on the etiology and the HCC microenvironment that influence tumor growth and immune control, will be crucial for physician decision-making among a variety of drugs to prescribe. In addition, markers of treatment efficacy are needed to speed the movement of patients towards other potentially effective treatments. Consequently, research to provide scientific data for the evidence-based management of liver cancer is guaranteed in the coming years and discussed here.

Hepatic Stellate Cell: A Potential Target for Hepatocellular Carcinoma

Liver cancer is a leading cause of cancer-related death worldwide, in which hepatocellular carcinoma (HCC) accounts for the majority. Despite the progression in treatment, the prognosis remains extremely poor for HCC patients. The mechanisms of hepatocarcinogenesis are complex, of which fibrosis is acknowledged as the pre-cancerous stage of HCC. Approximately, 80-90% of HCC develops in the fibrotic or cirrhotic livers. Hepatic stellate cells (HSCs), the main effector cells of liver fibrosis, could secret various biological contents to maintain the liver inflammation. By decades, HSCs are increasingly correlated with HCC in the tumor microenvironment. In this review, we summarized the underlying mechanisms that HSCs participated in the genesis and progression of HCC. HSCs secrete various bioactive contents and regulate tumor-related pathways, subsequently contribute to metastasis, angiogenesis, immunosuppression, chemoresistance and cancer stemness. The study indicates that HSC plays vital roles in HCC progression, suggesting it as a promising therapeutic target for HCC treatment.

Prognostic role of plasma level of angiopoietin-1, angiopoietin-2, and vascular endothelial growth factor in hepatocellular carcinoma

BACKGROUND

Most hepatocellular carcinomas (HCCs) are hypervascular, with characteristic features of hepatic arterial supply to the tumor. The factors involved in tumor angiogenesis include angiopoietin-1 (Ang-1), angiopoietin-2 (Ang-2), and vascular endothelial growth factor (VEGF).

AIM

To investigate the profiles of plasma levels of angiogenesis markers in patients with HCC and evaluate their roles in predicting overall survival (OS) and progression-free survival (PFS).

METHODS

Plasma samples from 240 prospectively enrolled HCC patients in the very early to advanced stages were used to measure the levels of Ang-1, Ang-2, and VEGF. Their associations with clinical characteristics, OS, and PFS were analyzed.

RESULTS

The median plasma levels of Ang-1, Ang-2, and VEGF were 3216 pg/mL, 1684 pg/mL, and 26.5 pg/mL, respectively. The plasma level of Ang-2 showed a significant increase from early stage [Barcelona clinic liver cancer (BCLC) A] to intermediate (BCLC B) and advanced stage HCC (BCLC C/D), whereas Ang-1, VEGF, and alpha-fetoprotein (AFP) levels in the plasma did not show any such changes. Multivariable analysis, propensity score-matched analysis, and time-dependent receiver operating curve analysis revealed that Ang-2 levels had the highest predictive power for OS and PFS. Neither Ang-1 nor VEGF was significantly associated with OS or PFS. The neutrophil-to-lymphocyte ratio was an independent factor for OS and PFS.

CONCLUSION

The plasma levels of Ang-2 correlated with liver function, tumor stage, and tumor invasiveness, showing better performance in predicting OS and PFS than AFP, Ang-1, or VEGF.

Correlation Between Vascular Endothelial Growth Factor and Long-Term Occurrence of HCV-Related Hepatocellular Carcinoma After Treatment with Direct-Acting Antivirals

We aimed to evaluate the correlation between vascular endothelial growth factor (VEGF) and long-term occurrence of hepatocellular carcinoma after HCV treatment with direct-acting antivirals (DAAs) and the HCC stage. Two groups with HCV-related liver cirrhosis and HCC were included: group 1, HCC following DAAs; group 2, HCC did not receive DAAs. The serum level of VEGF and HCC staging was evaluated. The duration between DAAs and HCC was 21.81 ± 11.66 months. Portal vein thrombosis (PVT) was observed more in group 1 (31%). VEGF was relatively elevated in group 1 compared to group 2. HCC patients after DAAs, showed elevated VEGF with frequent PVT.

Screening and identification of angiogenesis-related genes as potential novel prognostic biomarkers of hepatocellular carcinoma through bioinformatics analysis

Hepatocellular carcinoma (HCC) is a malignant tumor with high morbidity and mortality, which makes the prognostic prediction challenging. Angiogenesis appears to be of critical importance in the progression and metastasis of HCC. Some of the angiogenesis-related genes promote this process, while other anti-angiogenesis genes suppress tumor growth and metastasis. Therefore, the comprehensive prognostic value of multiple angiogenesis-related genes in HCC needs to be further clarified. In this study, the mRNA expression profile of HCC patients and the corresponding clinical data were acquired from multiple public databases. Univariate Cox regression analysis was utilized to screen out differentially expressed angiogenesis-related genes with prognostic value. A multigene signature was established with the least absolute shrinkage and selection operator Cox regression in the Cancer Genome Atlas cohort, and validated through an independent cohort. The results suggested that a total of 16 differentially expressed genes (DEGs) were associated with overall survival (OS) and a 7-gene signature was constructed. The risk score of each patient was calculated using this signature, the median value of which was used to divide these patients into a high-risk group and a low-risk group. Compared with the low-risk group, the patients in the high-risk group had a poor prognosis. The risk score was an independent predictor for OS through multivariate Cox regression analysis. Then, unsupervised learning was used to verify the validity of this 7-gene signature. A nomogram by further integrating clinical information and the prognostic signature was utilized to predict prognostic risk and individual OS. Functional enrichment analyses demonstrated that these DEGs were enriched in the pathways of cell proliferation and mitosis, and the immune cell infiltration was significantly different between the two risk groups. In summary, a novel angiogenesis-related genes signature could be used to predict the prognosis of HCC and for targeted therapy.

Hepatic stellate cells - from past till present: morphology, human markers, human cell lines, behavior in normal and liver pathology

Hepatic stellate cell (HSC), initially analyzed by von Kupffer, in 1876, revealed to be an extraordinary mesenchymal cell, essential for both hepatocellular function and lesions, being the hallmark of hepatic fibrogenesis and carcinogenesis. Apart from their implications in hepatic injury, HSCs play a vital role in liver development and regeneration, xenobiotic response, intermediate metabolism, and regulation of immune response. In this review, we discuss the current state of knowledge regarding HSCs morphology, human HSCs markers and human HSC cell lines. We also summarize the latest findings concerning their roles in normal and liver pathology, focusing on their impact in fibrogenesis, chronic viral hepatitis and liver tumors.

High expression of Tie-2 predicts poor prognosis in primary high grade serous ovarian cancer

Background

Antiangiogenic therapy, although part of standard treatment in ovarian cancer, has variable efficacy. Furthermore, little is known about the prognostic biomarkers and factors influencing angiogenesis in cancer tissue. We evaluated the expression of angiopoietin-2 and two endothelial tyrosine kinase receptors, Tie-1 and Tie-2, and assessed their value in the prediction of survival in patients with malignant epithelial ovarian cancer. We also compared the expression of these factors between primary high grade serous tumors and their distant metastasis.

Materials and methods

We evaluated 86 women with primary epithelial ovarian cancer. Matched distal omental metastasis were investigated in 18.6% cases (N = 16). The expression levels of angiogenic factors were evaluated by immunohistochemistry in 306 specimens and by qRT-PCR in 111 samples.

Results

A high epithelial expression level of Tie-2 is a significant prognostic factor in primary high grade serous ovarian cancer. It predicted significantly shorter overall survival both in univariate (p<0.001) and multivariate survival analyses (p = 0.022). Low angiopoietin-2 expression levels in primary ovarian tumors were significantly associated with shorter overall survival (p = 0.015) in the univariate survival analysis. A low expression of angiopoietin-2 was also significantly related to high grade tumors, size of residual tumor after primary surgery and the recurrence of cancer (p = 0.008; p = 0.012; p = 0.018) in the whole study population. The expression of angiopoietin-2 and Tie-2 was stronger in distal omental metastasis than in primary high grade serous tumors in matched-pair analysis (p = 0.001; p = 0.002).

Conclusions

The angiogenic factor, angiopoietin-2, and its receptor Tie-2 seem to be significant prognostic factors in primary epithelial ovarian cancer. Their expression levels are also increased in metastatic lesions in comparison with primary tumors.

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.

Targeting Cancer Associated Fibroblasts in Liver Fibrosis and Liver Cancer Using Nanocarriers

Cancer associated fibroblasts (CAF) and the extracellular matrix (ECM) produced by them have been recognized as key players in cancer biology and emerged as important targets for cancer treatment and drug discovery. Apart from their presence in stroma rich tumors, such as biliary, pancreatic and subtypes of hepatocellular cancer (HCC), both CAF and certain ECM components are also present in cancers without an overt intra-tumoral desmoplastic reaction. They support cancer development, growth, metastasis and resistance to chemo- or checkpoint inhibitor therapy by a multitude of mechanisms, including angiogenesis, ECM remodeling and active immunosuppression by secretion of tumor promoting and immune suppressive cytokines, chemokines and growth factors. CAF resemble activated hepatic stellate cells (HSC)/myofibroblasts, expressing α-smooth muscle actin and especially fibroblast activation protein (FAP). Apart from FAP, CAF also upregulate other functional cell surface proteins like platelet-derived growth factor receptor β (PDGFRβ) or the insulin-like growth factor receptor II (IGFRII). Notably, if formulated with adequate size and zeta potential, injected nanoparticles home preferentially to the liver. Several nanoparticular formulations were tested successfully to deliver dugs to activated HSC/myofibroblasts. Thus, surface modified nanocarriers with a cyclic peptide binding to the PDGFRβ or with mannose-6-phosphate binding to the IGFRII, effectively directed drug delivery to activated HSC/CAF in vivo. Even unguided nanohydrogel particles and lipoplexes loaded with siRNA demonstrated a high in vivo uptake and functional siRNA delivery in activated HSC, indicating that liver CAF/HSC are also addressed specifically by well-devised nanocarriers with optimized physicochemical properties. Therefore, CAF have become an attractive target for the development of stroma-based cancer therapies, especially in the liver.

Development and validation of a novel immune-related prognostic model in hepatocellular carcinoma

Background

Growing evidence has suggested that immune-related genes play crucial roles in the development and progression of hepatocellular carcinoma (HCC). Nevertheless, the utility of immune-related genes for evaluating the prognosis of HCC patients are still lacking. The study aimed to explore gene signatures and prognostic values of immune-related genes in HCC.

Methods

We comprehensively integrated gene expression data acquired from 374 HCC and 50 normal tissues in The Cancer Genome Atlas (TCGA). Differentially expressed genes (DEGs) analysis and univariate Cox regression analysis were performed to identify DEGs that related to overall survival. An immune prognostic model was constructed using the Lasso and multivariate Cox regression analyses. Furthermore, Cox regression analysis was applied to identify independent prognostic factors in HCC. The correlation analysis between immune-related signature and immune cells infiltration were also investigated. Finally, the signature was validated in an external independent dataset.

Results

A total of 329 differentially expressed immune‐related genes were detected. 64 immune‐related genes were identified to be markedly related to overall survival in HCC patients using univariate Cox regression analysis. Then we established a TF-mediated network for exploring the regulatory mechanisms of these genes. Lasso and multivariate Cox regression analyses were applied to construct the immune-based prognostic model, which consisted of nine immune‐related genes. Further analysis indicated that this immune-related prognostic model could be an independent prognostic indicator after adjusting to other clinical factors. The relationships between the risk score model and immune cell infiltration suggested that the nine-gene signature could reflect the status of tumor immune microenvironment. The prognostic value of this nine-gene prognostic model was further successfully validated in an independent database.

Conclusions

Together, our study screened potential prognostic immune-related genes and established a novel immune-based prognostic model of HCC, which not only provides new potential prognostic biomarkers and therapeutic targets, but also deepens our understanding of tumor immune microenvironment status and lays a theoretical foundation for immunotherapy.

MicroRNAs Involved in Metastasis of Hepatocellular Carcinoma: Target Candidates, Functionality and Efficacy in Animal Models and Prognostic Relevance

Hepatocellular carcinoma (HCC) is responsible for the second-leading cancer-related death toll worldwide. Although sorafenib and levantinib as frontline therapy and regorafenib, cabazantinib and ramicurimab have now been approved for second-line therapy, the therapeutic benefit is in the range of only a few months with respect to prolongation of survival. Aggressiveness of HCC is mediated by metastasis. Intrahepatic metastases and distant metastasis to the lungs, lymph nodes, bones, omentum, adrenal gland and brain have been observed. Therefore, the identification of metastasis-related new targets and treatment modalities is of paramount importance. In this review, we focus on metastasis-related microRNAs (miRs) as therapeutic targets for HCC. We describe miRs which mediate or repress HCC metastasis in mouse xenograft models. We discuss 18 metastasis-promoting miRs and 35 metastasis-inhibiting miRs according to the criteria as outlined. Six of the metastasis-promoting miRs (miR-29a, -219-5p, -331-3p, 425-5p, -487a and -1247-3p) are associated with unfavourable clinical prognosis. Another set of six down-regulated miRs (miR-101, -129-3p, -137, -149, -503, and -630) correlate with a worse clinical prognosis. We discuss the corresponding metastasis-related targets as well as their potential as therapeutic modalities for treatment of HCC-related metastasis. A subset of up-regulated miRs -29a, -219-5p and -425-5p and down-regulated miRs -129-3p and -630 were evaluated in orthotopic metastasis-related models which are suitable to mimic HCC-related metastasis. Those miRNAs may represent prioritized targets emerging from our survey.

Activated hepatic stellate cells promote angiogenesis in hepatocellular carcinoma by secreting angiopoietin-1

Angiogenesis is the central pathological process in hepatocellular carcinoma (HCC), and its progression is affected by tumor cells and the microenvironment. Activated hepatic stellate cells (aHSCs) are the most significant stromal cells involved in HCC. This study was aimed to explore the effects and mechanisms of aHSCs on angiogenesis in HCC. We isolated primary hepatoma cells, aHSCs, and hepatic vascular endothelial cells from human HCC samples. Then, we performed a novel in vitro assay and in vivo experiment in a nude mouse HCC model to investigate the functions of aHSCs on angiogenesis in HCC. Our results demonstrated that aHSCs are the primary sources of angiopoietin-1 (Ang-1) in human HCC in vitro, and aHSCs could promote hepatic vascular endothelial cell (HVEC) growth by secreting Ang-1. Furthermore, aHSCs could induce HVEC microtubule formation, and this ability was reduced when Ang-1 expression was silenced in aHSCs. In addition, CD34 expression in a nude mouse HCC model was downregulated when Ang-1 messenger RNA was silenced in aHSCs. Our data also indicated that HSC Ang-1 expression could be inhibited by overexpressing Raf kinase inhibitor protein. Therefore, we suggest that aHSCs promote angiogenesis through secreting Ang-1, potentially providing an interesting target for antiangiogenic therapies for HCC.

The Evaluation of Angiogenesis Markers in Hepatocellular Carcinoma and Precursor Lesions in Liver Explants From a Single Institution

Hepatocellular carcinoma (HCC) is a global health problem associated with chronic liver disease. Precursor lesions are described, and the correct diagnosis of liver nodules is paramount when considering liver transplantation. We evaluated the immunohistochemical expression of vascular endothelial growth factor (VEGF) and angiopoietin-2 in HCC and precursors lesion in a single institution series of whole liver explants between 2013 and 2015, evaluating morphologic and clinical variables. The study comprised 67 patients (32.8% female) and 107 nodules. The mean age of the patients was 52.7 years (29 to 70 y). There were no significant epidemiologic differences among malignant lesions, dysplastic nodules, and regenerative nodules. Angiopoietin-2 expression was significantly more expressed in carcinoma when compared with regenerative lesions (P<0.0001). A statistically significant relationship was noted between the expression of VEGF in hepatocytes and Ang-2 expression in the small vasculature (P=0.006). VEGF expression also correlated significantly with the number of nonpaired arteries (P=0.03), although it was not useful in separating benign from malignant cases. We identified a sensitivity of 54% and a specificity of 96% using angiopoietin-2, and a sensitivity of 68.7% and a specificity of 31.2% when using VEGF for the diagnosis of HCC. There was no significant correlation between the immunohistochemical parameters and the clinical staging, the number of gross lesions, and the histologic grade in cases of HCC. Angiopoietin-2 may be a candidate biomarker in assessing liver nodules in transplant patients, and may assist in the diagnosis of difficult lesions and in small biopsies pretransplant.

Monitoring serum proangiogenic cytokines from hepatocellular carcinoma patients treated with sorafenib

BACKGROUND AND AIM

Several factors, including proangiogenic cytokines, have been reported as predictive markers for the treatment effect of sorafenib in patients with hepatocellular carcinoma (HCC); however, most of them were determined based on one-time measurements before treatment.

METHODS

We consecutively recruited 80 advanced HCC patients who were treated with sorafenib prospectively. Serum levels of eight proangiogenic cytokines and the appearance of adverse events were monitored periodically, and their correlations with the prognoses of the patients were evaluated.

RESULTS

Among six significant risk factors for overall survival in univariate analyses, high angiopoietin-2 (hazard ratio, 2.06), high hepatocyte growth factor (hazard ratio, 2.08), and poor performance status before the treatment (hazard ratio, 2.48) were determined as independent risk factors. In addition, high angiopoietin-2 at the time of progressive disease was a marker of short post-progression survival (hazard ratio, 4.27). However, there was no significant variable that predicted short progression-free survival except the presence of hepatitis B virus surface antigen.

CONCLUSIONS

Predictions of overall survival and post-progression survival were possible by periodically measuring serum proangiogenic cytokines, especially angiopoietin-2, in patients with HCC treated with sorafenib.

The Role of Fibrosis and Liver-Associated Fibroblasts in the Pathogenesis of Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is one of the most aggressive types of cancer and lacks effective therapeutic approaches. Most HCC develops in the setting of chronic liver injury, hepatic inflammation, and fibrosis. Hepatic stellate cells (HSCs) and cancer-associated fibroblasts (CAFs) are key players in liver fibrogenesis and hepatocarcinogenesis, respectively. CAFs, which probably derive from HSCs, activate into extracellular matrix (ECM)-producing myofibroblasts and crosstalk with cancer cells to affect tumor growth and invasion. In this review, we describe the different components which form the HCC premalignant microenvironment (PME) and the tumor microenvironment (TME), focusing on the liver fibrosis process and the biology of CAFs. We will describe the CAF-dependent mechanisms which have been suggested to promote hepatocarcinogenesis, such as the alteration of ECM, CAF-dependent production of cytokines and angiogenic factors, CAF-dependent reduction of immuno-surveillance, and CAF-dependent promotion of epithelial-mesenchymal transition (EMT). New knowledge of the fibrosis process and the role of CAFs in HCC may pave the way for new therapeutic strategies for liver cancer.

The Role of Fibrosis and Liver-Associated Fibroblasts in the Pathogenesis of Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is one of the most aggressive types of cancer and lacks effective therapeutic approaches. Most HCC develops in the setting of chronic liver injury, hepatic inflammation, and fibrosis. Hepatic stellate cells (HSCs) and cancer-associated fibroblasts (CAFs) are key players in liver fibrogenesis and hepatocarcinogenesis, respectively. CAFs, which probably derive from HSCs, activate into extracellular matrix (ECM)-producing myofibroblasts and crosstalk with cancer cells to affect tumor growth and invasion. In this review, we describe the different components which form the HCC premalignant microenvironment (PME) and the tumor microenvironment (TME), focusing on the liver fibrosis process and the biology of CAFs. We will describe the CAF-dependent mechanisms which have been suggested to promote hepatocarcinogenesis, such as the alteration of ECM, CAF-dependent production of cytokines and angiogenic factors, CAF-dependent reduction of immuno-surveillance, and CAF-dependent promotion of epithelial-mesenchymal transition (EMT). New knowledge of the fibrosis process and the role of CAFs in HCC may pave the way for new therapeutic strategies for liver cancer.

Spontaneous regression of hepatocellular carcinoma with reduction in angiogenesis-related cytokines after treatment with sodium-glucose cotransporter 2 inhibitor in a cirrhotic patient with diabetes mellitus

Spontaneous regression of hepatocellular carcinoma (HCC) is a rare event, and the pathogenesis remains unclear. Here, we present a case of spontaneous regression of HCC after treatment with sodium-glucose cotransporter 2 inhibitor (SGLT2i) in a cirrhotic patient with diabetes mellitus (DM). A 68-year-old man regularly visited our hospital for follow-up of HCC after treatment with transcatheter arterial chemoembolization, and management of liver cirrhosis and type 2 DM. Contrast-enhanced computed tomography scan showed a hypervascular tumor in the liver and elevated serum α-fetoprotein levels, indicating the recurrence of HCC. Simultaneously, the hemoglobin A1c value increased to 8.0%; therefore, he was treated with SGLT2i (canagliflozin 100 mg/day). Ten weeks after the initiation of SGLT2i treatment, he was admitted to our hospital for treatment of recurrent HCC. However, the hypervascular tumor had disappeared, and the elevated serum α-fetoprotein level had decreased to normal limits, indicating spontaneous regression of HCC. In addition, an angiogenesis array analysis revealed downregulated protein expression of matrix metalloproteinase-8, angiopoietin-1/2, platelet-derived growth factor-AA, and prolactin at 10 weeks after SGLT2i treatment. In this report, we first describe a case of spontaneous regression of HCC with reduction in angiogenesis-related cytokines after SGLT2i treatment.

Clinical and prognostic significance of circulating levels of angiopoietin-1 and angiopoietin-2 in hepatocellular carcinoma

Angiopoietin-1 (Ang-1) and angiopoietin-2 (Ang-2) play critical roles in angiogenesis in hepatocellular carcinoma (HCC). In addition, recent data suggest that Ang-1/Ang-2 are involved in regulating the immune response. The aim of our study was to explore the clinical prognostic significance of plasma Ang-1 and Ang-2 in HCC. We prospectively enrolled and collected data and blood samples from 767 HCC patients treated at MD Anderson Cancer Center between 2001 and 2014. Controls consisted of cirrhotic patients (n = 75) and healthy volunteers (n = 200). The cutoff value was the median level of each angiogenic factor. Overall survival (OS) was estimated by Kaplan–Meier curves and compared by the log-rank test. Higher plasma Ang-2 was significantly associated with advanced clinicopathologic features of advanced HCC and lower OS. Median OS was 61.8 months (95% confidence interval [CI], 45.1–78.5 months) for low Ang-2 compared with 28.5 months (95% CI, 24.8–32.1 months) for high Ang-2 (p < 0.001). In contrast, higher Ang-1 was associated with longer OS. Median OS was 37.2 months (95% CI, 31.0–43.4 months) for high Ang-1 compared with 26.2 months (95% CI, 22.2–30.3 months) for those with low Ang-1 (p = 0.043). In conclusion, our findings indicate that plasma Ang-1 and Ang-2 levels are potential diagnostic and prognostic biomarkers in HCC.

Molecular Mechanisms Involved in HCC Recurrence after Direct-Acting Antiviral Therapy

Chronic hepatitis C is associated with a high risk of developing hepatocellular carcinoma (HCC) because of a direct effect of the Hepatitis C Virus (HCV) proteins and an indirect oncogenic effect of chronic inflammation and impaired immune response. The treatment of chronic hepatitis C markedly reduces all-cause mortality; in fact, interferon-based treatment has shown a reduction of HCC incidence of more than 70%. The recent introduction of the highly effective direct-acting antivirals (DAAs) has completely changed the scenario of chronic hepatitis C (CHC) with rates of HCV cure over 90%. However, an unexpectedly high incidence of HCC recurrence was observed in patients after DAA treatment (27% versus 0.4–2% in patients who received interferon treatment). The mechanism that underlies the high rate of tumor relapse is currently unknown and is one of the main issues in hepatology. We reviewed the possible mechanisms involved in HCC recurrence after DAA treatment.

Reactive Ductules Are Associated With Angiogenesis and Tumor Cell Proliferation in Pediatric Liver Cancer

While reactive ductules (RDs) have been observed in viral hepatitis, biliary atresia, nonalcoholic fatty liver disease, and adult hepatocellular carcinoma (HCC), RDs in pediatric liver cancer remain uncharacterized. This study investigated the relationship of RDs with angiogenic paracrine factors, the extent of angiogenesis, and tumor cell proliferation in pediatric hepatoblastoma (HBL)/HCC livers. We quantified the extent of RDs and their expression of paracrine factors that include vascular endothelial growth factor (VEGF), vascular endothelial growth factor D (VEGFD), platelet‐derived growth factor C, and angiopoietin 1 (ANGPT1). In addition, we performed immunohistochemical detection of the endothelial marker clusters of differentiation (CD)34 and the proliferation marker Ki67 followed by correlation analyses. In HBL, we found the percentage of RDs with Ki67 expression (% Ki67+ RDs) significantly correlated with intratumoral Ki67+ areas (r = 0.5138, P = 0.0349) and % ANGPT1+ RDs positively correlated with % Ki67+ RDs (r = 0.5851, P = 0.0136). In HCC, the high ANGPT1+ RDs group (i.e., cases with % ANGPT1+ RDs ≥50) exhibited high intratumoral Ki67+ areas compared to the low ANGPT1+ RDs group. In the combined HBL and HCC liver tumor group, there was a positive association between % platelet‐derived growth factor C+ RDs and intratumoral Ki67+ areas (r = 0.4712, P = 0.0099) and the high VEGFD+ RDs group (≥50%) exhibited a high number of peritumoral CD34+ vessels compared to the low VEGFD+ RDs group. Conclusion: Paracrine factor‐expressing RDs are associated with angiogenesis and proliferation of pediatric liver tumors.

Phase II Study of First-Line Trebananib Plus Sorafenib in Patients with Advanced Hepatocellular Carcinoma

Lessons Learned.

Trebananib leveraging anti‐angiogenic mechanism that is distinct from the classic sorafenib anti‐vascular endothelial growth factor inhibition did not demonstrate improved progression‐free survival at 4 months in patients with advanced hepatocellular carcinoma (HCC).

In support of previously reported high Ang‐2 levels’ association with poor outcome in HCC for patients, trebananib treatment with lower baseline Ang‐2 at study entry was associated with improved overall survival to 22 months and may suggest future studies to be performed within the context of low baseline Ang‐2.

Background.

Ang‐1 and Ang‐2 are angiopoietins thought to promote neovascularization via activation of the Tie‐2 angiopoietin receptor. Trebananib sequesters Ang‐1 and Ang‐2, preventing interaction with the Tie‐2 receptor. Trebananib plus sorafenib combination has acceptable toxicity. Elevated Ang‐2 levels are associated with poor prognosis in hepatocellular carcinoma (HCC).

Methods.

Patients with HCC, Eastern Cooperative Oncology Group ≤2, and Childs‐Pugh A received IV trebananib at 10 mg/kg or 15 mg/kg weekly plus sorafenib 400 mg orally twice daily. The study was planned for ≥78% progression‐free survival (PFS) rate at 4 months relative to 62% for sorafenib historical control (power = 80% α = 0.20). Secondary endpoints included safety, tolerability, overall survival (OS), and multiple biomarkers, including serum Ang‐2.

Results.

Thirty patients were enrolled sequentially in each of the two nonrandomized cohorts. Demographics were comparable between the two arms and the historical controls. PFS rates at 4 months were 57% and 54% on the 10 mg/kg and 15 mg/kg trebananib cohorts, respectively. Median OS was 17 and 11 months, respectively. Grade 3 and above events noted in ≥10% of patients included fatigue, hypertension, diarrhea, liver failure, palmar‐plantar erythrodysesthesia syndrome, dyspnea, and hypophosphatemia. One death was due to hepatic failure. Serum Ang‐2 dichotomized at the median was associated with improved OS in both cohorts.

Conclusion.

There was no improvement in PFS rate at 4 months in either cohort, when compared with sorafenib historical control.

The Role of Cancer-Associated Fibroblasts and Fibrosis in Liver Cancer

Liver cancer is the second leading cause of cancer mortality worldwide, causing more than 700,000 deaths annually. Because of the wide landscape of genomic alterations and limited therapeutic success of targeting tumor cells, a recent focus has been on better understanding and possibly targeting the microenvironment in which liver tumors develop. A unique feature of liver cancer is its close association with liver fibrosis. More than 80% of hepatocellular carcinomas (HCCs) develop in fibrotic or cirrhotic livers, suggesting an important role of liver fibrosis in the premalignant environment (PME) of the liver. Cholangiocarcinoma (CCA), in contrast, is characterized by a strong desmoplasia that typically occurs in response to the tumor, suggesting a key role of cancer-associated fibroblasts (CAFs) and fibrosis in its tumor microenvironment (TME). Here, we discuss the functional contributions of myofibroblasts, CAFs, and fibrosis to the development of HCC and CCA in the hepatic PME and TME, focusing on myofibroblast- and extracellular matrix-associated growth factors, fibrosis-associated immunosuppressive pathways, as well as mechanosensitive signaling cascades that are activated by increased tissue stiffness. Better understanding of the role of myofibroblasts in HCC and CCA development and progression may provide the basis to target these cells for tumor prevention or therapy.

Liver metastases: Microenvironments and ex-vivo models

The liver is a highly metastasis-permissive organ, tumor seeding of which usually portends mortality. Its unique and diverse architectural and cellular composition enable the liver to undertake numerous specialized functions, however, this distinctive biology, notably its hemodynamic features and unique microenvironment, renders the liver intrinsically hospitable to disseminated tumor cells. The particular focus for this perspective is the bidirectional interactions between the disseminated tumor cells and the unique resident cell populations of the liver; notably, parenchymal hepatocytes and non-parenchymal liver sinusoidal endothelial, Kupffer, and hepatic stellate cells. Understanding the early steps in the metastatic seeding, including the decision to undergo dormancy versus outgrowth, has been difficult to study in 2D culture systems and animals due to numerous limitations. In response, tissue-engineered biomimetic systems have emerged. At the cutting-edge of these developments are ex vivo 'microphysiological systems' (MPS) which are cellular constructs designed to faithfully recapitulate the structure and function of a human organ or organ regions on a milli- to micro-scale level and can be made all human to maintain species-specific interactions. Hepatic MPSs are particularly attractive for studying metastases as in addition to the liver being a main site of metastatic seeding, it is also the principal site of drug metabolism and therapy-limiting toxicities. Thus, using these hepatic MPSs will enable not only an enhanced understanding of the fundamental aspects of metastasis but also allow for therapeutic agents to be fully studied for efficacy while also monitoring pharmacologic aspects and predicting toxicities. The review discusses some of the hepatic MPS models currently available and although only one MPS has been validated to relevantly modeling metastasis, it is anticipated that the adaptation of the other hepatic models to include tumors will not be long in coming.

Phase II trial of bevacizumab and erlotinib as a second-line therapy for advanced hepatocellular carcinoma

Trial registry

Clinicaltrials.gov #NCT01180959.

Background

Early clinical studies of bevacizumab and erlotinib in advanced hepatocellular carcinoma (HCC) have a tolerable toxicity and a promising clinical outcome. We evaluated the efficacy and tolerability of this combination as a second-line therapy for HCC refractory to sorafenib.

Methods

For this single-arm, Phase II study, we recruited patients with Child–Pugh class A or B liver disease, Eastern Cooperative Oncology Group performance status 0–2, and advanced HCC that was not amenable to surgical or regional therapies and treatment with sorafenib had failed (disease progressed or patient could not tolerate sorafenib). Patients received 10 mg/kg intravenous bevacizumab every 14 days and 150 mg oral erlotinib daily for 28-day cycles until progression. Tumor response was evaluated every two cycles using Response Evaluation Criteria in Solid Tumors. The primary end point was the 16-week progression-free survival rate. Secondary end points included time to progression and overall survival.

Results

A total of 44 patients were enrolled and had a median follow-up time of 33.8 months (95% confidence interval [CI]: 23.5 months – not defined). The 16-week progression-free survival rate was 43% (95% CI: 28%–59%), median time to progression was 3.9 months (95% CI: 2.0–8.3 months), and median overall survival duration was 9.9 months (95% CI: 8.3–15.5 months). Grade 3–4 adverse events included fatigue (13%), acne (11%), diarrhea (9%), anemia (7%), and upper gastrointestinal hemorrhage (7%).

Conclusion

Bevacizumab plus erlotinib was tolerable and showed a signal of survival benefit in the second-line setting for patients with advanced HCC. Because standard-of-care options are lacking in this setting, further studies to identify predictors of response to this regimen are warranted.

Contrast Enhanced MRI in the Diagnosis of HCC

Hepatocellular carcinoma (HCC) is the 6th most common cancer worldwide. Imaging plays a critical role in HCC screening and diagnosis. Initial screening of patients at risk for HCC is performed with ultrasound. Confirmation of HCC can then be obtained by Computed Tomography (CT) or Magnetic Resonance Imaging (MRI), due to the relatively high specificity of both techniques. This article will focus on reviewing MRI techniques for imaging HCC, felt by many to be the exam of choice for HCC diagnosis. MRI relies heavily upon the use of gadolinium-based contrast agents and while primarily extracellular gadolinium-based contrast agents are used, there is an emerging role of hepatobiliary contrast agents in HCC imaging. The use of other non-contrast enhanced MRI techniques for assessing HCC will also be discussed and these MRI strategies will be reviewed in the context of the pathophysiology of HCC to help understand the MR imaging appearance of HCC.

Evaluation of antiangiogenic efficacy in advanced hepatocellular carcinoma: Biomarkers and functional imaging

Many years after therapeutic wilderness, sorafenib finally showed a clinical benefit in patients with advanced hepatocellular carcinoma. After the primary general enthusiasm worldwide, some disappointments emerged particularly since no new treatment could exceed or at least match sorafenib in this setting. Without these new drugs, research focused on optimizing care of patients treated with sorafenib. One challenging research approach deals with identifying prognostic and predictive biomarkers of sorafenib in this population. The task still seems difficult; however appropriate investigations could resolve this dilemma, as observed for some malignancies where other drugs were used.

Hepatocellular carcinoma: Where there is unmet need

Hepatocellular carcinoma (HCC) is a complex and heterogeneous tumor most commonly associated with underlying chronic liver disease, especially hepatitis. It is a growing problem in the United States and worldwide. There are two potential ways to prevent HCC. Primary prevention which is based on vaccination or secondary prevention involving agents that slow down carcinogenesis. Several pathways have been thought to play a role in the development of HCC; specifically, those involving vascular endothelial growth factor (VEGF)-mediated angiogenesis, WNT, phosphatidylinositol 3-kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR), AMP-activated protein kinase (AMPK), and c-MET. Currently, there are only a limited number of drugs which have been proven as effective treatment options for HCC and several clinical trials are testing drugs which target aberrations in the pathways mentioned above. In this review, we discuss currently approved therapies, monotherapies and combination therapy for the treatment of HCC.

Hepatic stellate cells: central modulators of hepatic carcinogenesis

Hepatocellular carcinoma (HCC) represents the second most common cause of cancer-related death worldwide, and is increasing in incidence. Currently, our therapeutic repertoire for the treatment of HCC is severely limited, and therefore effective new therapies are urgently required. Recently, there has been increasing interest focusing on the cellular and molecular interactions between cancer cells and their microenvironment. HCC represents a unique opportunity to study the relationship between a diseased stroma and promotion of carcinogenesis, as 90 % of HCCs arise in a cirrhotic liver. Hepatic stellate cells (HSC) are the major source of extracellular proteins during fibrogenesis, and may directly, or via secreted products, contribute to tumour initiation and progression. In this review we explore the complex cellular and molecular interplay between HSC biology and hepatocarcinogenesis. We focus on the molecular mechanisms by which HSC modulate HCC growth, immune cell evasion and angiogenesis. This is followed by a discussion of recent progress in the field in understanding the mechanistic crosstalk between HSC and HCC, and the pathways that are potentially amenable to therapeutic intervention. Furthermore, we summarise the exciting recent developments in strategies to target HSC specifically, and novel techniques to deliver pharmaceutical agents directly to HSC, potentially allowing tailored, cell-specific therapy for HCC.

Proof of prometastatic niche induction by hepatic stellate cells

BACKGROUND

An interaction between tumor cells and the microenvironment, as well as the development of angiogenesis, are required to form liver metastases (LMs).

MATERIAL AND METHODS

Immunofluorescence detection of α-smooth muscle actin, desmin, Ki67, laminin, and CD31 was used to analyze the kinetics of tumor angiogenesis determinants, especially the contribution of hepatic stellate cells (HSCs) to angiogenesis in hepatic metastasis produced by intrasplenically injected LS174 colorectal cancer cells. Immunostaining was performed at various times (days 9, 14, 28, and 39).

RESULTS

At the earliest stage, micrometastases consisted of proliferating cancer cells, a well-organized network of activated HSCs and laminin deposits. No vascular network was observed. As the LMs grew in size, an organized vascular network appeared; the laminin network colocalized with CD31 immunostaining. At the later stages, all the immunostained markers became peripheral as a central necrosis developed. Purified activated HSCs isolated from transgenic mice livers developing hepatocellular carcinoma secreted laminin and showed enhanced human umbilical vein EC network formation in a Matrigel assay. In a coinjection LM experiment, activated HSCs enhanced the metastatic process. Moreover, colorectal LMs from six patients were analyzed, and a pattern of marker distribution similar to the coinjection experiment was found in human LMs.

CONCLUSIONS

For the first time, our results show that HSCs play a crucial role in organizing and accelerating the progression of metastasis in modulating the prometastatic niche, interacting with colorectal cancer cell recruitment, and the organization of angiogenesis during colorectal LM development. Therefore, HSCs may be an early therapeutic target in colorectal cancer therapies.

Angiopoietin 2 as a therapeutic target in hepatocellular carcinoma treatment: current perspectives

Hepatocellular carcinoma (HCC) is a hypervascular malignancy and is the third leading cause of death worldwide. The disease has multiple predisposing risk factors and limited treatment options. Although the precise mechanism(s) underlying HCC is unknown, several pathways have been implicated in its development. HCC is a vascular tumor and angiogenesis is believed to play an important role in its progression. Hypoxia is believed to increase the expression of vascular endothelial growth factor (VEGF) through the expression of the hypoxia-inducible factor-1α. VEGF and angiopoietin 2 (Ang2) are expressed on cancer cells, whereas angiopoietin 1 (Ang1) occurs predominantly in support cells of large blood cells as well as stromal, endothelial, and tumor cells. Ang2 is concomitantly an agonist and antagonist of angiopoietin 1 and is expressed during vascular remodeling. This prevents vascular stability and allows VEGF to stimulate endothelial cells. Ang2 is expressed along with growing blood vessels, destabilizing the vascular integrity. Inhibiting Ang2 can, on the other hand, promote vesicular stability and decrease angiogenesis. We discuss in this review angiopoietin as a therapeutic target alone or in combination with other therapies.

Antiangiogenic strategies in hepatocellular carcinoma: current status

Hepatocellular carcinoma is a leading cause of cancer death worldwide in both adult and pediatric patients. Despite many options, no ideal treatment exists for this highly malignant tumor, and management strategies have varied accordingly. Angiogenesis, the formation of new blood vessels, is an essential component of hepatocellular carcinoma biology. Innovative approaches such as targeting the nontransformed, less resistant, tumor-supporting endothelial cells are currently under investigation in hepatocellular carcinoma. This review will focus on the current knowledge of the pathophysiology of hepatocellular carcinoma angiogenesis, as well as the reported data with angiogenesis inhibitors against hepatocellular carcinoma.

Treatment with EGCG in NSCLC leads to decreasing interstitial fluid pressure and hypoxia to improve chemotherapy efficacy through rebalance of Ang-1 and Ang-2

AIM

Microvasculature and microenvironment play important roles in proliferation, invasion, metastasis and prognosis in non-small cell lung cancer (NSCLC), which might be altered by many anti-angiogenic drugs. Epigallocatechin-3-gallate (EGCG), a natural anti-angiogenesis agent refined from green tea, was defined to have multiple effects on angiogenesis factors, such as endothelial growth factor (VEGF), platelet-derived growth factor (PDGF) and angiopoietins (ANGs). Hypothesizing that EGCG might regulate microvasculature and microenvironment in NSCLC, the effects of EGCG on microvessel density (MVD), expression of Ang-1 and Ang-2, interstitial fluid pressure (IFP), tumor hypoxia, and chemotherapy sensitivity were examined.

METHODS AND RESULTS

EGCG treatment of A549 cells in mice bearing xenografts in vivo led to a significant decrease of MVD detected by CD31, and of Ang-2 expression detected by quantum dots double-label immunofluorescence assessment, while Ang-1 decreased with no significance. Decreased IFP was measured by the Wink-in-needle method, while hypoxia was assessed by polarographic electrode and pimonidazole (PIMO) immunohistochemistry. Assuming that these changes would increase response to chemotherapy, tumor growth studies were p[erformed in nude mice with xenografts, which were then treated with EGCG and the chemotherapeutic agent cisplatin. EGCG therapy combined with cisplatin led to synergistic inhibition of tumor growth, compared with administration of each treatment separately (P < 0.001). According to linear regression analysis, IFP was positively correlated with PIMO staining (R(2) = 0.618, P = 0.002), Ang-2 was correlated with MVD (R(2) = 0.423, P = 0.022), IFP (R(2) = 0.663, P = 0.01) and PIMO staining (R(2) = 0.694, P = 0.01).

CONCLUSION

IFP and delivery of oxygen might be improved by rebalance of Ang-1/Ang-2 under the treatment of EGCG in NSCLC, which also acts as a sensitizer of chemotherapy. These studies established a new mechanism for using EGCG as an adjuvant chemotherapy agent through modifying microvasculature and microenvironment.

Antiangiogenic treatment in hepatocellular carcinoma: the balance of efficacy and safety

Hepatocellular carcinoma (HCC) is a severe complication of advanced liver disease with a worldwide incidence of more than 600,000 patients per year. Liver function, clinical performance status, and tumor size are considered in the Barcelona Clinic Liver Cancer (BCLC) system. While curative treatment options are available for early stages, most patients present with intermediate- or advanced-stage HCC, burdened with a poor prognosis, substantially influenced by the degree of liver-function impairment. Hypervascularization is a major characteristic of HCC, and antiangiogenic treatments are the basis of treatment in noncurative stages, including interventional and pharmacological treatments. Currently, the tyrosine-kinase inhibitor sorafenib is still the only approved drug for HCC. Further improvements in survival in patients with intermediate- and advanced-stage HCC may be anticipated by both multimodal approaches, such as combination of interventional and systemic treatments, and new systemic treatment options. Until now, the Phase III development of other tyrosine-kinase inhibitors in patients with advanced HCC has failed due to minor efficacy and/or increased toxicity compared to sorafenib. However, promising Phase II data have been reported with MET inhibitors in this hard-to-treat population. This review gives a critical overview of antiangiogenic drugs and strategies in intermediate- and advanced-stage HCC, with a special focus on safety.

Hepatic stellate cells and metastatic liver neoplasms

Hepatic stellate cells (HSCs) were first described in the 19th century as a type of multi-functional mesenchymal cells. They are considered as the component of liver microenvironment because of their capacity to differentiate into myofibroblasts which are highly proliferative and have collagen secretion capacity. This paper reviews the interactions between tumor cells and HSCs in liver microenvironment and discusses mechanisms by which tumor-derived factors activate HSCs, and in turn, activated HSC promotes metastatic tumor growth. The interactions between tumor cells and HSCs in liver microenvironment can be regarded as an "amplification loop". The activation of HSCs is a complex process that is regulated by multiple pathways, such as the transforming growth factor-β and platelet-derived growth factor signaling pathways. HSCs provide a possible therapeutic target for liver metastases to effectively increase the survival of patients.