The expression profile of glypican-3 and its relation to macrophage population in human hepatocellular carcinoma

Integrated single-cell transcriptomics reveals the hypoxia-induced inflammation-cancer transformation in NASH-derived hepatocellular carcinoma

Non-alcoholic fatty liver disease (NAFLD) has emerged as the primary risk factor for hepatocellular carcinoma (HCC), owing to improved vaccination rates of Hepatitis B and the increasing prevalence of metabolic syndrome related to obesity. Although the importance of innate and adaptive immune cells has been emphasized, the malignant transformation of hepatocytes and their intricate cellular network with the immune system remain unclear. The study incorporated four single-cell transcriptomic datasets of liver tissues covering healthy and NAFLD-related disease status. To identify the subsets and functions of hepatocytes and macrophages, we employed differential composition analysis, functional enrichment analysis, pseudotime analysis, and scenic analysis. Furthermore, an experimental mouse model for the transformation of nonalcoholic steatohepatitis into hepatocellular carcinoma was established for validation purposes. We defined CYP7A1+ hepatocytes enriched in precancerous lesions as 'Transitional Cells' in the progression from NAFLD to HCC. CYP7A1+ hepatocytes upregulated genes associated with stress response, inflammation and cancer-associated pathways and downregulated the normal hepatocyte signature. We observed that hypoxia activation accompanied the entire process of inflammation-cancer transformation. Hepatocyte-derived HIF1A was gradually activated during the progression of NAFLD disease to adapt to the hypoxic microenvironment and hepatocytes under hypoxic environment led to changes in the metabolism, proliferation and angiogenesis, promoting the occurrence of tumours. Meanwhile, hypoxia induced the polarization of RACK1+ macrophages that enriched in the liver tissues of NASH towards immunosuppressed TREM2+ macrophages. Moreover, immunosuppressive TREM2+ macrophages were recruited by tumour cells through the CCL15-CCR1 axis to enhance immunosuppressive microenvironment and promote NAFLD-related HCC progression. The study provides a deep understanding of the development mechanism of NAFLD-related HCC and offers theoretical support and experimental basis for biological targets, drug research, and clinical application.

Glypican-3: A Novel and Promising Target for the Treatment of Hepatocellular Carcinoma

Glypican-3 (GPC3) is a membrane-associated proteoglycan that is specifically up-regulated in hepatocellular carcinoma (HCC) although rarely or not expressed in normal liver tissues, making it a perfect diagnostic and treatment target for HCC. Several GPC3-based clinical trials are ongoing and recently several innovative GPC3-targeted therapeutic methods have emerged with exciting results, including GPC3 vaccine, anti-GPC3 immunotoxin, combined therapy with immune checkpoint blockades (ICBs), and chimeric antigen receptor (CAR) T or NK cells. Here, we review the value of GPC3 in the diagnosis and prognosis of HCC, together with its signaling pathways, with a specific focus on GPC3-targeted treatments of HCC and some prospects for the future GPC3-based therapeutic strategies in HCC.

Current Trends in Non-Invasive Imaging of Interactions in the Liver Tumor Microenvironment Mediated by Tumor Metabolism

Simple Summary

Deregulated tumor metabolism is known to shape the tumor microenvironment and directly affect the local immune response, promoting tumor growth, metastasis, and resistance to treatment. However, the metabolic profile or tumor cells, and therefore, the composition of their microenvironment, are highly variable among patients and even within the same tumor, resulting in heterogeneous response rates to oncologic therapies, making patient selection a key issue. This review article focuses on non-invasive imaging techniques that aim to visualize the crosstalk between tumor cells and their microenvironment in liver cancer mediated by tumor metabolism. In addition to improved tumor detection, such imaging tools may be able to provide a more accurate characterization of the individual tumor and ultimately improve understanding, as well as guide personalized treatment regimens for patients with liver cancer.

Abstract

With the increasing understanding of resistance mechanisms mediated by the metabolic reprogramming in cancer cells, there is a growing clinical interest in imaging technologies that allow for the non-invasive characterization of tumor metabolism and the interactions of cancer cells with the tumor microenvironment (TME) mediated through tumor metabolism. Specifically, tumor glycolysis and subsequent tissue acidosis in the realms of the Warburg effect may promote an immunosuppressive TME, causing a substantial barrier to the clinical efficacy of numerous immuno-oncologic treatments. Thus, imaging the varying individual compositions of the TME may provide a more accurate characterization of the individual tumor. This approach can help to identify the most suitable therapy for each individual patient and design new targeted treatment strategies that disable resistance mechanisms in liver cancer. This review article focuses on non-invasive positron-emission tomography (PET)- and MR-based imaging techniques that aim to visualize the crosstalk between tumor cells and their microenvironment in liver cancer mediated by tumor metabolism.

A bispecific antibody targeting GPC3 and CD47 induced enhanced antitumor efficacy against dual antigen-expressing HCC

Glypican-3 (GPC3) is a well-characterized hepatocellular carcinoma (HCC)-associated antigen, yet anti-GPC3 therapies have achieved only minimal clinical progress. CD47 is a ubiquitously expressed innate immune checkpoint that promotes evasion of tumors from immune surveillance. Given both the specific expression of GPC3 in HCC and the known phagocytosis inhibitory effect of CD47 in liver cancer, we hypothesized that a bispecific antibody (BsAb) that co-engages with GPC3 and CD47 may offer excellent antitumor efficacy with minimal toxicity. Here, we generated a novel BsAb: GPC3/CD47 biAb. With the use of both in vitro and in vivo assays, we found that GPC3/CD47 biAb exerts strong antitumor activity preferentially against dual antigen-expressing tumor cells. In hCD47/human signal regulatory protein alpha (hCD47/hSIRPα) humanized mice, GPC3/CD47 biAb had an extended serum half-life without causing systemic toxicity. Importantly, GPC3/CD47 biAb induced enhanced Fc-mediated effector functions to dual antigen-expressing HCC cells in vitro, and both macrophages and neutrophils are required for its strong efficacy against xenograft HCC tumors. Notably, GPC3/CD47 biAb outperformed monotherapies and a combination therapy with anti-CD47 and anti-GPC3 monoclonal antibodies (mAbs) in a xenograft HCC model. Our study illustrates a strategy for improving HCC treatment by boosting innate immune responses and presents new insights to inform antibody design for the future development of innovative immune therapies.

Immunological distinctions between nonalcoholic steatohepatitis and hepatocellular carcinoma

Nonalcoholic fatty liver disease (NAFLD), the most common cause of chronic liver disease, ranges from simple hepatic steatosis to nonalcoholic steatohepatitis (NASH), which is a more aggressive form characterized by hepatocyte injury, inflammation, and fibrosis. Increasing evidence suggests that NASH is a risk factor for hepatocellular carcinoma (HCC), which is the fifth most common cancer worldwide and the second most common cause of cancer-related death. Recent studies support a strong mechanistic link between the NASH microenvironment and HCC development. The liver has a large capacity to remove circulating pathogens and gut-derived microbial compounds. Thus, the liver is a central player in immunoregulation. Altered immune responses are tightly associated with the development of NASH and HCC. The objective of this study was to differentiate the roles of specific immune cell subsets in NASH and HCC pathogenesis.

Clarifying the role of specific cells in the immune system in the transition from non-alcoholic fatty liver disease (NAFLD) to liver cancer will help to understand disease progression and may open avenues towards new preventive and therapeutic strategies. NAFLD is the most common chronic liver disease. Growing evidence suggests that its most aggressive form, non-alcoholic steatohepatitis (NASH), can promote the development of liver cancer, the second most common cause of cancer deaths worldwide. Chang-Woo Lee and colleagues at Sungkyunkwan University, Suwon, South Korea review the immunological distinction between NASH and liver cancer, focusing on the levels and activities of six key types of immune system cells. Chronic inflammation mediated by the immune system can create conditions for NAFLD, NASH and liver cancer to develop and worsen.

The Role of Glypicans in Cancer Progression and Therapy

Glypicans are a family of heparan sulfate proteoglycans that are attached to the cell membrane via a glycosylphosphatidylinositol anchor. Glypicans interact with multiple ligands, including morphogens, growth factors, chemokines, ligands, receptors, and components of the extracellular matrix through their heparan sulfate chains and core protein. Therefore, glypicans can function as coreceptors to regulate cell proliferation, cell motility, and morphogenesis. In addition, some glypicans are abnormally expressed in cancers, possibly involved in tumorigenesis, and have the potential to be cancer-specific biomarkers. Here, we provide a brief review focusing on the expression of glypicans in various cancers and their potential to be targets for cancer therapy.

Glypican-3: A New Target for Diagnosis and Treatment of Hepatocellular Carcinoma

Liver cancer is the second leading cause of cancer-related deaths worldwide, and hepatocellular carcinoma is the most common type. The pathogenesis of hepatocellular carcinoma is concealed, its progress is rapid, its prognosis is poor, and the mortality rate is high. Therefore, novel molecular targets for hepatocellular carcinoma early diagnosis and development of targeted therapy are critically needed. Glypican-3, a cell-surface glycoproteins in which heparan sulfate glycosaminoglycan chains are covalently linked to a protein core, is overexpressed in HCC tissues but not in the healthy adult liver. Thus, Glypican-3 is becoming a promising candidate for liver cancer diagnosis and immunotherapy. Up to now, Glypican-3 has been a reliable immunohistochemical marker for hepatocellular carcinoma diagnosis, and soluble Glypican-3 in serum has becoming a promising marker for liquid biopsy. Moreover, various immunotherapies targeting Glypican-3 have been developed, including Glypican-3 vaccines, anti- Glypican-3 immunotoxin and chimeric-antigen-receptor modified cells. In this review, we summarize and analyze the structure and physicochemical properties of Glypican-3 molecules, then review their biological functions and applications in clinical diagnosis, and explore the diagnosis and treatment strategies based on Glypican-3.

Time-to-event modelling of effect of codrituzumab on overall survival in patients with hepatocellular carcinoma

AIMS

Codrituzumab (GC33) is a recombinant, humanized mAb that binds to glypican-3 (GPC3), an oncofetal protein highly expressed in hepatocellular carcinoma (HCC). This investigation aimed to identify clinically relevant factors that may affect the overall survival (OS) in HCC patients treated with codrituzumab and to quantitatively annotate their effects.

METHODS

Codrituzumab exposure was estimated by a population pharmacokinetics model with a nonlinear elimination pathway. Analysis of OS was performed using a time-to-event model in 181 patients with advanced HCC. The model was tested with the addition of various covariates, including levels of immune biomarkers, such as CD16 (measured in terms of molecules of equivalent soluble fluorophore; CD16_MESF ) and CD4, codrituzumab exposure and potential prognostic biomarkers of HCC such as baseline tumour size and soluble GPC3.

RESULTS

The time-to-event model estimated a prolonged OS (>3 months) in patients with codrituzumab exposure of ≥230 μg ml^-1 and high CD16_MESF level (>5.26 × 10⁵ MESF at least). The Weibull model was selected as the base hazard model. The baseline tumour size was included in the hazard model as a parameter independent of the drug effect. A logistic model was applied to explain the effects of drug exposure and CD16_MESF level.

CONCLUSIONS

The final model indicates that adequate drug exposure plus a favourable immune environment are associated with prolonged OS. This quantitative model should be further validated with emerging data so as to guide study design in future clinical trials.

Glypican-3: A promising biomarker for hepatocellular carcinoma diagnosis and treatment

Liver cancer is the second leading cause of cancer-related deaths, and hepatocellular carcinoma (HCC) is the most common type. Therefore, molecular targets are urgently required for the early detection of HCC and the development of novel therapeutic approaches. Glypican-3 (GPC3), an oncofetal proteoglycan anchored to the cell membrane, is normally detected in the fetal liver but not in the healthy adult liver. However, in HCC patients, GPC3 is overexpressed at both the gene and protein levels, and its expression predicts a poor prognosis. Mechanistic studies have revealed that GPC3 functions in HCC progression by binding to molecules such as Wnt signaling proteins and growth factors. Moreover, GPC3 has been used as a target for molecular imaging and therapeutic intervention in HCC. To date, GPC3-targeted magnetic resonance imaging, positron emission tomography, and near-infrared imaging have been investigated for early HCC detection, and various immunotherapeutic protocols targeting GPC3 have been developed, including the use of humanized anti-GPC3 cytotoxic antibodies, treatment with peptide/DNA vaccines, immunotoxin therapies, and genetic therapies. In this review, we summarize the current knowledge regarding the structure, function, and biology of GPC3 with a focus on its clinical potential as a diagnostic molecule and a therapeutic target in HCC immunotherapy.

Prognostic significance of the peripheral blood absolute monocyte count in patients with locally advanced or metastatic hepatocellular carcinoma receiving systemic chemotherapy

BACKGROUND

The prognostic significance of the circulating absolute monocyte count (AMC) in patients with locally advanced hepatocellular carcinoma (HCC) is uncertain. This study was designed to assess the association of circulating AMC with survival outcomes in patients diagnosed with locally advanced or metastatic HCC receiving systemic chemotherapy.

MATERIALS AND METHODS

Between January 1, 2005 and December 30, 2012, locally advanced or metastatic HCC patients who had Child-Pugh stage A or B disease and received systemic chemotherapy were retrospectively enrolled. Patient features including gender, age, extrahepatic metastasis, Child-Pugh stage, serum alpha-fetoprotein(AFP) level and AMC were collected to investigate their prognostic impact on overall survival(OS).

RESULTS

A total of 216 patients were eligible for the study. The optimal cut-off value of AMC for OS analysis was 0.38×10⁹/L. Median OS was 5.84 months in low-AMC group (95% confidence interval [CI], 5.23 to 6.45), and 5.21 months in high-AMC group (95% CI, 4.37 to 6.04; p=0.003). In COX multivariate analysis, elevated AMC remained as an independent prognostic factor for worse OS (HR, 1.578; 95% CI, 1.120 to 2.223, p=0.009).

CONCLUSIONS

Our results indiicate that circulating AMC is confirmed to be an independent prognostic factor for OS in patients with locally advanced or metastatic HCC receiving systemic chemotherapy.

Randomized phase II placebo controlled study of codrituzumab in previously treated patients with advanced hepatocellular carcinoma

BACKGROUND & AIMS

Codrituzumab, a humanized monoclonal antibody against Glypican-3 (GPC3) that is expressed in hepatocellular carcinoma (HCC), interacts with CD16/FcγRIIIa and triggers antibody-dependent cytotoxicity. Codrituzumab was studied vs. placebo in a randomized phase II trial in advanced HCC patients who had failed prior systemic therapy.

METHODS

Patients with advanced HCC who had failed prior systemic therapy, ⩾18years, Eastern cooperative oncology group (ECOG) 0-1, Child-Pugh A were randomized 2:1 to biweekly codrituzumab 1600mg vs. placebo. Patients were stratified based on GPC3 immunohistochemical expression: 2+/3+, 1+, and 0. Primary endpoint was progression free survival. Secondary endpoints include overall survival (OS), tolerability, pharmacokinetics, and an exploratory endpoint in biomarkers analysis.

RESULTS

185 patients were enrolled: 125 received codrituzumab and 60 placebo: Median age 64/63, 85/75% male, 46/42% Asian, ECOG 0 65/63%, 74/77% having vascular invasion and/or extra-hepatic metastasis. 84%/70% had prior sorafenib. Drug exposure was 98.4% of planned dose, with an identical adverse events profile between the 2 groups. The median progression free survival and overall survival in the codrituzumab vs. placebo groups in months were: 2.6 vs. 1.5 (hazard ratios 0.97, p=0.87), and 8.7 vs. 10 (hazard ratios 0.96, p=0.82). Projected Ctrough at cycle 3day 1 based exposure, high CD16/FcγRIIIa on peripheral immune cells, and GPC3 expression in the tumor, were all associated with prolonged progression free survival and overall survival.

CONCLUSIONS

Codrituzumab did not show clinical benefit in this previously treated HCC population. Whether higher codrituzumab drug exposure or the use of CD16 and GPC3 as potential biomarkers would improve outcome remain unanswered questions.

LAY SUMMARY

Codrituzumab is a manufactured antibody against a liver cancer protein called glypican-3. In this clinical trial, codrituzumab was not found be effective against liver cancer. It was suggested though that a higher dose of codrituzumab or selecting patients with high level of glypican-3 or its mediator CD16 might improve outcome.

CLINICAL TRIAL REGISTRATION

This trial is registered at Clinicaltrials.gov (NCT01507168).

Glypican-3 is a prognostic factor and an immunotherapeutic target in hepatocellular carcinoma

Glypican-3 (GPC3) is a cell surface oncofetal proteoglycan that is anchored by glycosylphosphatidylinositol. Whereas GPC3 is abundant in fetal liver, its expression is hardly detectable in adult liver. Importantly, GPC3 is overexpressed in hepatocellular carcinoma (HCC), and several immunohistochemical studies reported that overexpression predicts a poorer prognosis for HCC patients. Therefore, GPC3 would serve as a useful molecular marker for HCC diagnosis and also as a target for therapeutic intervention in HCC. Indeed, some immunotherapy protocols targeting GPC3 are under investigations; those include humanized anti-GPC3 cytotoxic antibody, peptide vaccine and immunotoxin therapies. When considering the clinical requirements for GPC3-targeting therapy, companion diagnostics to select the appropriate HCC patients are critical, and both immunohistochemical analysis of tissue sections and measurement of serum GPC3 level have been suggested for this purpose. This review summarizes current knowledge regarding the clinical implication of GPC3 detection and targeting in the management of patients with HCC.

GPC3 expression in mouse ovarian cancer induces GPC3‑specific T cell-mediated immune response through M1 macrophages and suppresses tumor growth

Glypican-3 (GPC3) is specifically expressed in ovarian clear cell carcinoma (OCCC), hepatocellular carcinoma (HCC), and melanoma and lung cancer. GPC3 is being explored as a potential candidate for OCCC and HCC immunotherapy. As a tumor-associated antigen, induction of immune response of GPC3 in ovarian cancer remains elusive. We established a GPC3 transgenic mouse ovarian cancer cell line, OV2944-HM-1 (HM-1), and used the intraperitoneal ovarian cancer mouse model to investigate immune response in GPC3-expressing tumor. We found that GPC3 expression in the tumor increased F4/80⁺CD86⁺ macrophage (M1) proportion and caused GPC3-specific CD8⁺ T cell immune responses, and prolonged mouse survival. Our results demonstrated that GPC3 expression induced T cell-mediated immune response in this mouse ovarian cancer model and also provided supportive evidence that GPC3 is an ideal target for ovarian cancer immunotherapy.

Aberrant expression of monocarboxylate transporter 4 in tumour cells predicts an unfavourable outcome in patients with hepatocellular carcinoma

BACKGROUND & AIMS

The tumour cell microenvironment, which includes local oxygen saturation, pericellular pH and stromal cells, can modulate tumour progression. This study determined the prognostic impact of infiltrating tumour-associated macrophages and the expression of monocarboxylate transporter 4 (MCT4) and glypican 3 (GPC3) in hepatocellular carcinoma (HCC) clinical specimens.

METHODS

A total of 225 cases of resected HCC were subjected to immunohistochemical analyses of CD68, CD204, MCT4 and GPC3. Immunoreactivities and other common clinicopathological parameters were subjected to univariate prognostic analyses for overall survival (OS, n = 225) and disease-free survival (DFS, n = 222). All variables with prognostic impact were further analysed in multivariate analysis.

RESULTS

Increased intratumoural infiltration of CD204-positive or MCT4-positive macrophages suggested shorter OS (P = 0.015 or P = 0.001 respectively), but DFS was not altered. The GPC3 score (with an emphasis on circumferential immunoreactivity) was correlated with shorter OS and DFS. Aberrant expression of MCT4 in HCC cells was observed in a subset of HCC cases (21%, 47/225). In those cases, significantly poorer OS (P < 0.0001) and DFS (P = 0.0003) were observed, and there was a positive correlation with the intratumoural infiltration of CD204- or MCT4-positive macrophages and the GPC3 score. Multivariate analysis showed that aberrant MCT4 expression in HCC cells was an independent prognostic factor for shorter OS (P = 0.018) and DFS (P = 0.006) after resection of HCC.

CONCLUSION

Aberrant expression of MCT4 in carcinoma cells serves as a novel, independent prognostic factor for HCC, indicating a poorer patient outcome.

Critical analysis of the potential of targeting GPC3 in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a leading cause of cancer-related deaths worldwide. The treatment options for patients with advanced HCC are limited, and novel treatment strategies are required urgently. Glypican-3 (GPC3), a member of the glypican family of heparan sulfate proteoglycans, is overexpressed in 72%−81% of HCC cases, and is correlated with a poor prognosis. GPC3 regulates both stimulatory and inhibitory signals, and plays a key role in regulating cancer cell growth. GPC3 is released into the serum, and so might be a useful diagnostic marker for HCC. GPC3 is also used as an immunotherapeutic target in HCC. A Phase I study of a humanized anti-GPC3 monoclonal antibody, GC33, revealed a good safety profile and potential antitumor activity, and a Phase II trial is currently ongoing. In addition, the authors’ investigator-initiated Phase I study of a GPC3-derived peptide vaccine showed good safety and tolerability, and demonstrated that the GPC3 peptide-specific cytotoxic T-lymphocyte frequency in peripheral blood correlated with overall survival in HCC patients. A sponsor-initiated Phase I clinical trial of a three-peptide cocktail vaccine, which includes a GPC3-derived peptide, is also underway. GPC3 is currently recognized as a promising therapeutic target and diagnostic marker for HCC. This review introduces the recent progress in GPC3 research, from biology to clinical impact.

The role of macrophage polarization in infectious and inflammatory diseases

Macrophages, found in circulating blood as well as integrated into several tissues and organs throughout the body, represent an important first line of defense against disease and a necessary component of healthy tissue homeostasis. Additionally, macrophages that arise from the differentiation of monocytes recruited from the blood to inflamed tissues play a central role in regulating local inflammation. Studies of macrophage activation in the last decade or so have revealed that these cells adopt a staggering range of phenotypes that are finely tuned responses to a variety of different stimuli, and that the resulting subsets of activated macrophages play critical roles in both progression and resolution of disease. This review summarizes the current understanding of the contributions of differentially polarized macrophages to various infectious and inflammatory diseases and the ongoing effort to develop novel therapies that target this key aspect of macrophage biology.

First-in-man phase I study of GC33, a novel recombinant humanized antibody against glypican-3, in patients with advanced hepatocellular carcinoma

PURPOSE

GC33 is a novel recombinant fully humanized monoclonal antibody that binds to human glypican-3 (GPC3). The antitumor activity of GC33 was shown in preclinical models of hepatocellular carcinoma (HCC). This first-in-man clinical trial was conducted to evaluate the safety, pharmacokinetic characteristics, and preliminary efficacy of GC33 in patients with advanced HCC.

EXPERIMENTAL DESIGN

Patients with measurable, histologically proven, advanced HCC were enrolled to a dose-escalation study of GC33 (2.5-20 mg/kg) given intravenously weekly. The primary endpoint was to determine the maximum tolerated dose of GC33 for further development. Pharmacokinetic characteristics were measured in serum samples. Immunohistochemistry was conducted on tumor biopsies to evaluate GPC3 expression. Tumor response was assessed every 8 weeks using Response Evaluation Criteria in Solid Tumors criteria.

RESULTS

Twenty patients were enrolled and treated with GC33. A maximum tolerated dose was not reached as there were no dose-limiting toxicities (DLT) up to the highest planned dose level. Common adverse events with all grades included fatigue (50%), constipation (35%), headache (35%), and hyponatremia (35%). The incidence of adverse events seemed not to be dose dependent. Trough serum concentrations at steady state were in excess of target concentration at doses of 5 mg/kg or greater. Median time to progression (TTP) was 26.0 weeks in the GPC3 high expression group and 7.1 weeks in the low expression group (P = 0.033).

CONCLUSION

This study shows that GC33 was well tolerated in advanced HCC and provides preliminary evidence that GPC3 expression in HCC may be associated with the clinical benefit to GC33 that warrants prospective evaluation.

The inflammatory microenvironment in hepatocellular carcinoma: a pivotal role for tumor-associated macrophages. Biomed Res Int. 2013;2013:187204. [PMID: 23533994 PMCID: PMC3591180 DOI: 10.1155/2013/187204]

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

Role of tumor-associated macrophages in the growth and metastasis of hepatocellular carcinoma

The relationship between tumor-associated macrophages (TAMs) and tumors has become a hot research topic in recent years. New evidence suggests that macrophages play a dual role in tumorigenesis and metastasis. Besides anti-tumor effects, macrophages in the tumor microenvironment can facilitate angiogenesis and extracellular matrix breakdown and remodeling and promote tumor cell mobility. In this article we summarize the role of TAMs in the growth and metastasis of hepatocellular carcinoma in terms of TAM recruitment, inflammation, angiogenesis, and epithelial-mesenchymal transition (EMT).

Early transcriptional responses of HepG2-A16 liver cells to infection by Plasmodium falciparum sporozoites

Invasion of hepatocytes by Plasmodium sporozoites deposited by Anopheles mosquitoes, and their subsequent transformation into infective merozoites is an obligatory step in the initiation of malaria. Interactions between the sporozoites and hepatocytes lead to a distinct, complex and coordinated cellular and systemic host response. Little is known about host liver cell response to sporozoite invasion, or whether it is primarily adaptive for the parasite, for the host, or for both. Our present study used gene expression profiling of human HepG2-A16 liver cells infected with Plasmodium falciparum sporozoites to understand the host early cellular events and factors influencing parasite infectivity and sporozoite development. Our results show that as early as 30 min following wild-type, non-irradiated sporozoite exposure, the expressions of at least 742 genes was selectively altered. These genes regulate diverse biological functions, such as immune processes, cell adhesion and communications, metabolism pathways, cell cycle regulation, and signal transduction. These functions reflect cellular events consistent with initial host cell defense responses, as well as alterations in host cells to sustain sporozoites growth and survival. Irradiated sporozoites gave very similar gene expression pattern changes, but direct comparative analysis between liver gene expression profiles caused by irradiated and non-irradiated sporozoites identified 29 genes, including glypican-3, that were specifically up-regulated only in irradiated sporozoites. Elucidating the role of this subset of genes may help identify the molecular basis for the irradiated sporozoites inability to develop intrahepatically, and their usefulness as an immunogen for developing protective immunity against pre-erythrocytic stage malaria.

Generation of a humanized anti-glypican 3 antibody by CDR grafting and stability optimization. Anticancer Drugs. 2010;21:907-916. [PMID: 20847643 DOI: 10.1097/cad.0b013e32833f5d68]

Glypican 3 (GPC3), a glycosylphosphatidylinositol-anchored heparan sulfate proteoglycan, is expressed in a majority of hepatocellular carcinoma tissues. The murine monoclonal antibody GC33 that specifically binds to the COOH-terminal part of GPC3 causes strong antibody-dependent cellular cytotoxicity against hepatocellular carcinoma cells and exhibits strong antitumor activity in the xenograft models. To apply GC33 for clinical use, we generated a humanized GC33 from complementarity-determining region grafting with the aid of both the hybrid variable region and two-step design methods. The humanized antibody bound to GPC3 specifically and induced antibody-dependent cellular cytotoxicity as effectively as a chimeric GC33 antibody. To improve stability of the humanized GC33, we further optimized humanized GC33 by replacing the amino acid residues that may affect the structure of the variable region of a heavy chain. Substitution of Glu6 with Gln in the heavy chain significantly improved the stability under high temperatures. GC33 also has the risk of deamidation of the -Asn-Gly- sequence in the complementarity-determining region 1 of the light chain. As substitution of Asn diminished the antigen binding, we changed the neighboring Gly to Arg to avoid deamidation. The resulting humanized anti-GPC3 antibody was as efficacious as chimeric GC33 against the HepG2 xenograft and is now being evaluated in clinical trials.

Prognostic significance of circumferential cell surface immunoreactivity of glypican-3 in hepatocellular carcinoma

BACKGROUND

GC33 is a recently developed monoclonal antibody against human glypican-3 (GPC3), which is significantly upregulated in hepatocellular carcinoma (HCC). GC33 recognizes a GPC3 ectodomain and shows significant antitumour activity in vivo. Thus, humanized GC33 antibody may be a promising tool for treating HCC having cell surface GPC3 expression.

AIMS

This study aims to determine the specificity, subcellular localization and prognostic impact of GPC3 immunoreactivity detected by GC33 in HCC clinical specimens.

METHODS

Immunohistochemical analysis was performed for 194 cases of resected HCC and prognostic analysis was performed for 185 eligible cases. Two antigen retrieval methods (autoclave and protease pretreatments) were used for immunohistochemistry and compared. The immunoscore system reflecting circumferential membranous GPC3 immunoreactivity was developed using either the autoclave or protease methods. The GPC3 mRNA level was analysed by quantitative real-time reverse transcription-polymerase chain reaction.

RESULTS

GC33 immunostaining after autoclave is a sensitive method and revealed the GPC3 expression (≥20% of tumour cells) in the majority (77%) of HCC samples tested. Alternatively, protease pretreatment showed lower sensitivity, but was superior for evaluating the intensity and subcellular localization of GPC3. Correlation between immunoscores and the GPC3 mRNA level was also confirmed. Subsequent clinicopathological analysis revealed worse prognoses in HCC patients with circumferential membranous GPC3 immunoreactivity. For HCC patients with hepatitis C virus (HCV) infection in particular, the high membranous GPC3 immunoreactivity was an independent prognostic factor for disease-free survival.

CONCLUSIONS

Circumferential membranous GPC3 immunoreactivity in HCC indicates poorer prognosis particularly in patients with HCV infection.

Glypican-3: a new target for cancer immunotherapy

Hepatocellular carcinoma (HCC) remains a common malignant cancer worldwide. There is an urgent need to identify new molecular targets for the development of novel therapeutic approaches. Herein, we review the structure, function and biology of glypican-3 (GPC3) and its role in human cancer with a focus on its potential as a therapeutic target for immunotherapy. GPC3 is a cell-surface protein that is over-expressed in HCC. Loss-of-function mutations of GPC3 cause Simpson-Golabi-Behmel syndrome (SGBS), a rare X-linked overgrowth condition. GPC3 binds Wnt and Hedgehog (Hh) signalling proteins. GPC3 is also able to bind basic growth factors such as fibroblast growth factor 2 through its heparan sulphate glycan chains. GPC3 is a promising candidate for liver cancer therapy given that it shows high expression in HCC. An anti-GPC3 monoclonal antibody has shown anti-cancer activity in mice and its humanised IgG molecule is currently undergoing clinical evaluation in patients with HCC. There is also evidence that soluble GPC3 may be a useful serum biomarker for HCC.