Therapeutic potential of targeting glypican-3 in hepatocellular carcinoma

GPC-3 in hepatocellular carcinoma; A novel biomarker and molecular target

Hepatocellular carcinoma (HCC) is a global health issue due to its late diagnosis and high recurrence rate. The early detection and diagnosis of HCC with specific and sensitive biomarkers and using novel treatment approaches to improve patient outcomes are essential. Glypican-3 (GPC-3) is a cell surface proteoglycan that is overexpressed in many tumors, including HCC. GPC-3 could be used as a specific biomarker for HCC early detection and could be a potential target for precise therapeutic strategies. Effective identification of GPC-3 could improve both diagnosis and targeted therapy of HCC. Moreover, targeted therapy using GPC-3 could result in a better treatment outcome. Recently, GPC3-targeted therapies have been used in different investigational therapeutic approaches like bi-specific/monoclonal antibodies, peptide vaccines, and CAR T cell therapies. This study aims to highlight the theranostic potential of GPC-3 as a novel biomarker for early detection and as a potential molecular target for HCC treatment as well.

Diagnostic and Prognostic Value of Protein Post-translational Modifications in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is a common malignant tumor with high incidence and cancer mortality worldwide. Post-translational modifications (PTMs) of proteins have a great impact on protein function. Almost all proteins can undergo PTMs, including phosphorylation, acetylation, methylation, glycosylation, ubiquitination, and so on. Many studies have shown that PTMs are related to the occurrence and development of cancers. The findings provide novel therapeutic targets for cancers, such as glypican-3 and mucin-1. Other clinical implications are also found in the studies of PTMs. Diagnostic or prognostic value, and response to therapy have been identified. In HCC, it has been shown that glycosylated alpha-fetoprotein (AFP) has a higher detection rate for early liver cancer than conventional AFP. In this review, we mainly focused on the diagnostic and prognostic value of PTM, in order to provide new insights into the clinical implication of PTM in HCC.

The extracellular matrix in hepatocellular carcinoma: Mechanisms and therapeutic vulnerability

The tumor microenvironment (TME) is influenced by a "disorganized" extracellular matrix (ECM) that sensitizes cancer cells toward mechanical stress, signaling, and structural alterations. In hepatocellular carcinoma (HCC), lack of knowledge about key ECM proteins driving the TME refractory to targeted therapies poses a barrier to the identification of new therapeutic targets. Herein, we discuss the contributions of various ECM components that impact hepatocytes and their surrounding support network during tumorigenesis. In addition, the underpinnings by which ECM proteins transduce mechanical signals to the liver TME are detailed. Finally, in view of the bidirectional feedback between the ECM, transformed hepatocytes, and immune cells, we highlight the potential role of the ECM disorganization process in shaping responses to immune checkpoint inhibitors and targeted therapies. Our comprehensive characterization of these ECM components may provide a roadmap for innovative therapeutic approaches to restrain HCC.

Imaging ligands targeting glypican-3 receptor expression in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the third leading cause of cancer mortality. Early detection of HCC is important since potentially curative therapies exist in the initial stages of HCC; no curative therapies exist for late-stage HCC. However, the initial detection of HCC remains challenging due to the lack of symptoms during the early stage of the disease. Other methods of screening and detecting HCC, including blood serum tests and conventional imaging methods, remain inadequate due to genetic differences between patients and the high background activity of liver tissues. Thus, there is a need for an accurate imaging agent for the diagnosis, staging, and prognosis of HCC. Glypican-3 (GPC3) is an oncofetal receptor responsible for regulating cell division, growth, and survival. GPC3 is a clinically relevant biomarker for imaging and therapeutics, as its expression is HCC tumor-specific and absent from normal and other pathological liver tissues. The development of novel GPC3-targeting imaging agents has encompassed three classes of biomolecules: peptides, antibodies, and aptamers. These biomolecules serve as constructs for diagnostic imaging (demonstrating potential as positron emission tomography [PET], single-photon emission tomography [SPECT], and optical imaging agents) and HCC treatment delivery. More than 20 unique ligands have been identified in the literature as showing specificity for the GPC3 receptor. Although several ligands are currently under clinical investigation as therapies for HCC, clinical translation of GPC3-targeting ligands as imaging agents is lacking. This review highlights the current landscape of ligands targeting GPC3 and describes their promising possibilities as imaging agents for HCC.

Proteoglycans in Cancer: Friends or Enemies? A Special Focus on Hepatocellular Carcinoma

Simple Summary

Proteoglycans affect multiple molecular and cellular processes during the progression of solid tumors with a highly desmoplastic stroma, such as HCC. Due to their role in enhancing or limiting the traits of cancer cells underlying their aggressiveness, such as proliferation, angiogenesis, epithelial to mesenchymal transition (EMT), and stemness, these macromolecules could be exploited as molecular targets or therapeutic agents. Proteoglycans, such as biglycan, versican, syndecan-1, glypican-3, and agrin, promote HCC cell proliferation, EMT, and angiogenesis, while endostatin and proteoglycan 4 were shown to impair cancer neovascularization or to enhance the sensitivity of HCC cells to drugs, such as sorafenib and regorafenib. Based on this evidence, interventional strategies involving the use of humanized monoclonal antibodies, T cells engineered with chimeric antigen receptors, or recombinant proteins mimicking potentially curative proteoglycans, are being employed or may be adopted in the near future for the treatment of HCC.

Abstract

Proteoglycans are a class of highly glycosylated proteins expressed in virtually all tissues, which are localized within membranes, but more often in the pericellular space and extracellular matrix (ECM), and are involved in tissue homeostasis and remodeling of the stromal microenvironment during physiological and pathological processes, such as tissue regeneration, angiogenesis, and cancer. In general, proteoglycans can perform signaling activities and influence a range of physical, chemical, and biological tissue properties, including the diffusivity of small electrolytes and nutrients and the bioavailability of growth factors. While the dysregulated expression of some proteoglycans is observed in many cancers, whether they act as supporters or limiters of neoplastic progression is still a matter of controversy, as the tumor promoting or suppressive function of some proteoglycans is context dependent. The participation of multiple proteoglycans in organ regeneration (as demonstrated for the liver in hepatectomy mouse models) and in cancer suggests that these molecules actively influence cell growth and motility, thus contributing to key events that characterize neoplastic progression. In this review, we outline the main roles of proteoglycans in the physiology and pathology of cancers, with a special mention to hepatocellular carcinoma (HCC), highlighting the translational potential of proteoglycans as targets or therapeutic agents for the treatment of this disease.

Therapeutic efficacy of a Dioscorea membranacea extract in a rat model of hepatocellular carcinoma: Histopathological aspects

Hepatocellular carcinoma (HCC) is most common in adults and has a high mortality rate because of a lack of effective treatment options. We investigated the effect of a medicinal plant as a potential source of drugs against HCC. The rhizomes of Dioscorea membranacea Pierre (DM), Hua-Khao-Yen in Thai, are commonly used as ingredients for alternative treatment of cancer in Thailand. In this study, the anticancer effects of DM extract in HCC-bearing rats were evaluated with respect to gross morphology, histopathology, and leakage of liver enzymes. In untreated HCCs, typical features of liver cancer, including hepatic nodules, thick-cell cords, and pseudoglandular cell arrangements, were observed. In addition, the HCCs showed abnormal reticulin patterns and a high glypican3 expression. In HCC-bearing rats treated with DM the cancer areas and reticulin expression were significantly reduced compared to the untreated group (p < 0.01). Sorafenib, the standard drug to treat HCC, reduced the cancer area further, but increased leakage of liver enzymes and decreased serum albumin concentration, indicating liver toxicity. These findings suggest that DM has an anticancer effect on HCCs in an animal model in vivo with potentially less severe side effects than sorafenib. Therefore, further studies of DM’s mechanism of action in HCC should be carried out.

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DM exerted a mitigating effect on histopathology and membrane damage of HCC in rats.

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Its effect was similar to that of the standard drug sorafenib.

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It reduced the volume of cancer nodules without the serious hepatotoxic side effects seen after SF treatment.

Value of miR-1271 and glypican-3 in evaluating the prognosis of patients with hepatocellular carcinoma after transcatheter arterial chemoembolization

BACKGROUND

Hepatocellular carcinoma (HCC) is the third leading cause of cancer death, causing about 750000 deaths worldwide every year. Patients with advanced hepatocellular carcinoma will often only receive transcatheter arterial chemoembolization (TACE). Glypican-3 (GPC3) is one of the most promising serum markers for HCC. Abnormal expression of miRNAs may be involved in the occurrence and development of tumor.

AIM

To explore the value of miR-1271 and GPC3 in evaluating the prognosis of patients with HCC after TACE.

METHODS

From January 2016 to December 2018, 162 patients with advanced HCC who received TACE in our hospital were selected into the cancer group, and 162 patients who underwent physical examination during the same period were selected into the health group. The patients in the HCC group were treated with TACE. The changes of serum GPC3 and circulating miR-1271 in the HCC before and after TACE were analyzed. The expression of serum GPC3 was detected by enzyme-linked immunosorbent assay, and the expression of circulating miR-1271 was detected by real-time quantitative polymerase chain reaction. The methodological results of sensitivity, specificity, and accuracy of miR-1271 and GPC3 alone and joint detection of HCC were also evaluated.

RESULTS

The level of serum GPC3 in patients with HCC was significantly higher than that in healthy controls. GPC3 levels were increased in both HCC patients and those treated with TACE compared with healthy controls. After TACE, the level of serum GPC3 was significantly lower than that before treatment (P < 0.05), and the level of circulating miR-1271 was significantly higher than that before treatment (P < 0.05). There were 112 cases (69.14%) with remission (complete remission + complete remission + stable disease) and 50 cases (30.86%) with relapse disease progression in HCC patients. After TACE, the miR-1271 level in patients with remission and relapse was lower than that in the healthy group, and the GPC3 level was higher than that in the healthy group, the differences were statistically significant (P < 0.05). The miR-1271 of relapsed patients was lower than that of remission patients, and the level of GPC3 was higher than that of remission patients, and the difference was statistically significant (P < 0.05). The sensitivity of combined detection of miR-1271 and GPC3 was significantly higher than that of single detection, and the difference was statistically significant (P < 0.05); while the specificity of the two combined detections was lower than that of the single detection; and the accuracy was slightly higher than that of single detection, but the difference was not statistically significant.

CONCLUSION

The level of miR-1271 in patients with HCC was significantly increased and the level of GPC3 was decreased after TACE. Monitoring the levels of serum GPC3 and circulating miR-1271 has important clinical reference value for evaluating the prognosis of patients with HCC. The levels of serum GPC3 and circulating miR-1271 may help to determine tumor recurrence, evaluate survival status, and guide the next step of treatment.

Both glypican-3/Wnt/β-catenin signaling pathway and autophagy contributed to the inhibitory effect of curcumin on hepatocellular carcinoma

AIM

The aim of this study is to investigate the role of glypican-3(GPC3)/wnt/β-catenin signaling pathway and autophagy in the regulation of hepatocellular carcinoma (HCC) growth mediated by curcumin.

METHODS

HepG2 cells were treated with various concentrations of curcumin and/or GPC3-targeting siRNA in the presence or absence of 3-MA. Cell proliferation and apoptosis were determined by MTT and TUNEL assay, respectively. Expression of GPC3, β-catenin, c-myc, LC3, and Beclin1 was determined by western blotting. In addition, curcumin was tested in tumor xenografts mice model, Caliper IVIS Lumina II was used to monitor the tumor growth, and GPC3/wnt/β-catenin signaling proteins were determined by western blotting.

RESULTS

Curcumin treatment led to proliferation inhibition and apoptosis induction in HepG2 cells in a concentration-dependent manner, and suppressed HCC tumor growth in vivo. Further analysis showed that curcumin treatment inactivated Wnt/β-catenin signaling and decreased GPC3 expression, silencing of GPC3 expression promoted the effects of curcumin on Wnt/β-catenin signaling. In addition, inhibiting autophagy by 3-MA relieved curcumin-dependent down-regulation of GPC3.

CONCLUSION

Curcumin suppressed HCC tumor growth through down-regulating GPC3/wnt/β-catenin signaling pathway, which was partially mediated by activation of autophagy.

Role of Glycanation and Convertase Maturation of Soluble Glypican-3 in Inhibiting Proliferation of Hepatocellular Carcinoma Cells

Glypican 3 (GPC3) is a complex heparan sulfate proteoglycan associated with the outer surface of the plasma membrane by a glycosylphosphatidylinositol (GPI) anchor. It is also N-glycosylated and processed by a furin-like convertase. GPC3 has numerous biological functions. Although GPC3 is undetectable in normal liver tissue, it is abnormally and highly overexpressed in hepatocellular carcinoma (HCC). Interestingly, proliferation of HCC cells such as HepG2 and HuH7 is inhibited when they express a soluble form of GPC3 after lentiviral transduction. To obtain more insight into the role of some of its post-translational modifications, we designed a mutant GPC3, sGPC3m, without its GPI anchor, convertase cleavage site, and glycosaminoglycan chains. The highly pure sGPC3m protein strongly inhibited HuH7 and HepG2 cell proliferation in vitro and induced a significant increase in their cell doubling time. It changed the morphology of HuH7 cells but not that of HepG2. It induced the enlargement of HuH7 cell nuclear area and the restructuration of adherent cell junctions. Unexpectedly, for both cell types, the levels of apoptosis, cell division, and β-catenin were not altered by sGPC3m, although growth inhibition was very efficient. Overall, our data show that glycanation and convertase maturation are not required for sGPC3m to inhibit HCC cell proliferation.

Crosstalk between liver-related microRNAs and Wnt/β-catenin pathway in hepatocellular carcinoma patients

BACKGROUND AND STUDY AIMS

Hepatocellular carcinoma (HCC) is one of the most common cancers worldwide with highest incidence in Asia and Africa. MicroRNAs (miRNAs), a class of non-coding single stranded RNA, which not only post transcriptionally regulate gene expression but also respond to signaling molecules to affect cell functions such as Wnt/β-catenin signaling specifically in HCC. The goal of this study is to investigate the crosstalk between Wnt/β-catenin signaling proteins and microRNAs expression in HCC patients.

PATIENTS AND METHODS

Fresh tissue samples of 30 primary HCC patients and 10 control subjects were included. Expression level of 13 different miRNAs (miR-10a- miR-106b- miR-99a- miR-148a- miR-125b- miR-30e- miR-183- miR-155- miR-199a- miR-199a3p- miR-24- miR-122 and miR-215) were examined using real-time PCR assay. Five proteins involved in the Wnt/β-catenin pathway (β-catenin, APC, c-myc, survivin and cyclin D1) were analysed by immunohistochemistry technique. The correlation between miRNAs expression levels with protein expressions was assessed.

RESULTS

Up-regulation of miR-155 and miR-183 was reported in HCC patients compared to normal controls and this up-regulation was significantly correlated with liver cirrhosis in the case of miR-155 (p<0.05) referring to their oncogenic activity. Down-regulation was observed for 11 miRNAs in HCC indicating their tumour suppression activity. MiRNA-10a, miR-30e, miR-215, miR-125b and miR-148a were significantly correlated with the expression of important players in Wnt/β-catenin pathway including β-catenin, APC and c-myc (p<0.05). Detailed analysis revealed that miR-215 is associated with the grade of the disease and miR-125b is associated with HCV infection.

CONCLUSION

Collectively, our data showed potential role of miR-10a, miR-30e, miR-215, miR-125b and miR-148a as important mediators in HCC progression. Furthermore, their association with Wnt/β-catenin cascade proteins could be exploited to develop new therapeutic target strategies in HCC.

Glypican-3 and KRT19 are markers associating with metastasis and poor prognosis of pancreatic ductal adenocarcinoma

OBJECTIVE

Pancreatic ductal adenocarcinoma (PDAC) is a highly malignant tumor with metastasis in most patients at diagnosis. The molecular mechanisms associated with its high malignancy have not been fully elucidated. This study investigated the clinicopathological significances of GPC3 and KRT19 expression in PDAC.

METHODS

GPC3, KRT19, and CA19-9 protein expression were measured by immunohistochemistry.

RESULTS

GPC3 and KRT19 protein levels were overexpressed in PDAC tumors compared to normal pancreatic tissues, benign pancreatic tissues, and peritumoral tissues (P< 0.01). The percentage of positive GPC3 and KRT19 expression were significantly higher in PDAC patients with larger tumor size, poorly differentiated tumor, lymph node metastasis, invasion, and TNM stage III/IV disease than in patients with small tumor size, well-differentiated tumor, no lymph node metastasis and invasion, as well as TNM stage I/II stage disease (P< 0.05 or P< 0.01). Benign pancreatic lesions with positive GPC3 and KRT19 protein expression exhibited dysplasia or intraepithelial neoplasia. Kaplan-Meier survival analysis showed that PDAC patients with positive GPC3 and KRT19 expression survived significantly shorter than patients with negative GPC3 and KRT19 expression (P < 0.05 or P< 0.001). Cox multivariate analysis revealed that positive GPC3 and KRT19 expression were independent poor prognosis factors in PDAC patients.

CONCLUSIONS

GPC3 and KRT19 overexpression are associated with carcinogenesis, progression, and poor prognosis in patients with PDAC and a valuable biomarker for diagnosis of PDAC.

Expression of oncofetal antigen glypican-3 associates significantly with poor prognosis in HBV-related hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common malignancies worldwide with poor prognosis. However, its prognostic evaluation is still an urgent problem. The objectives of this present study were to investigate oncofetal antigen glypican-3 (GPC-3) expression in HCC and their match para-cancerous tissues by the array technology with immunohistochemistry and estimate its value as a novel prognostic marker for HCC. The incidence of GPC-3 expression was 95.7 % in the cancerous tissues with significantly higher (χ2 = 33.824, P < 0.001) than that in the para-cancerous tissues (52.2 %). Abnormal expression of GPC-3 in HCC tissues was markedly related to poor or moderate differentiation (P < 0.001), hepatitis B virus (HBV) infection (P = 0.004), periportal cancer embolus (P = 0.043), and tumor-node- metastasis staging (P = 0.038). According to the univariate and multivariate analysis, the overall survival of HCC patients with high GPC-3 level was significantly worse than those with low or without GPC-3 expression (P < 0.001), suggesting that abnormal GPC-3 expression should be an independent prognostic factor for HBV-related HCC patient's survival.

Drug delivery system targeting advanced hepatocellular carcinoma: Current and future

Hepatocellular carcinoma (HCC) has a fairly high morbidity and is notoriously difficult to treat due to long latent period before detection, multidrug resistance and severe drug-related adverse effects from chemotherapy. Targeted drug delivery systems (DDS) that can selectively deliver therapeutic drugs into tumor sites have demonstrated a great potential in cancer treatment, which could be utilized to resolve the limitations of conventional chemotherapy. Numerous preclinical studies of DDS have been published, but targeted DDS for HCC has yet to be made for practical clinical use. Since rational targeted DDS design should take cancer-specific properties into consideration, we have reviewed the biological and physicochemical properties of HCC extensively to provide a comprehensive understanding on HCC, and recent DDS studies on HCC, aiming to find some potential targeted DDSs for HCC treatment and a meaningful platform for further development of HCC treatments.

FROM THE CLINICAL EDITOR

Hepatocellular carcinoma has a high incidence worldwide and is known to be multidrug resistant. Thus, intensive research is being carried out to find better chemotherapeutic agents as well as new drug delivery systems. In this article, the authors reviewed in depth the current challenges facing new drug designs and also outlined novel targeted drug delivery systems (DDS) in the fight against HCC.

Glypican-3 is a biomarker and a therapeutic target of hepatocellular carcinoma

BACKGROUND

The carcinogenesis of hepatocellular carcinoma (HCC) is a multi-factorial, multi-step and complex process. Early diagnosis and effective treatments are of utmost importance. This review summarized the recent studies of oncofetal glypican-3 (GPC-3), a membrane-associated heparan sulfate proteoglycan, in the diagnosis and treatment of HCC.

DATA SOURCES

English-language reports published from June 2001 to September 2014 were searched from MEDLINE. The key words searched included: GPC-3, biomarker, target and HCC. The sensitivity, specificity, positive and negative predictive values were extracted, and the effect of GPC-3 targeted therapy on HCC was also evaluated.

RESULTS

GPC-3 plays a crucial role in HCC cell proliferation and metastasis. It mediates oncogenesis involving signaling pathways during hepatocyte malignant transformation. GPC-3 expression is increased in atypical hyperplasia and cancerous tissues. GPC-3 levels in HCC patients are related to HBV infection, TNM stage, periportal cancerous embolus, and extrahepatic metastasis. The diagnostic accuracy of the combination of serum GPC-3 and alpha-fetoprotein in HCC is up to 94.3%. Down-regulation of GPC-3 with specific siRNA or anti-GPC-3 antibody alters cell migration, metastasis and invasion behaviors. The nude mice xenograft tumor growth is inhibited by silencing GPC-3 gene transcription.

CONCLUSION

Oncofetal GPC-3 is a highly specific biomarker for the diagnosis of HCC and a promising target molecule for HCC gene therapy.

Primary colon cancer with a high serum PIVKA-II level

INTRODUCTION

Protein induced by vitamin K absence/antagonist-II (PIVKA-II) is an abnormal protein, and several reports have demonstrated the efficacy of PIVKA-II in the diagnosis of hepatocellular carcinoma (HCC). We report an extremely rare case of adenocarcinoma of the colon with a high serum PIVKA-II level.

PRESENTATION OF CASE

A 95-year-old woman presented with right lower quadrant pain and appetite loss. An abdominal computed tomography scan and ultrasonography showed an ascending colon tumor and multiple metastatic tumors in the liver. The serum level of PIVKA-II was extremely high, 11,900ng/mL. Colonoscopic examination revealed a tumor accompanied by an ulcer in the ascending colon, which was highly suspicious for malignancy. Multiple biopsies showed well-differentiated adenocarcinoma of the colon, which was evaluated as colon cancer, stage IV. PIVKA-II-productive colon cancer was confirmed. Chemotherapy with TS-1 was administered. The patient died 3 months after initial admission.

DISCUSSION

The expression of PIVKA-II was detected in non-cancer areas, with non-specific expression observed in plasma cells in our case. There might be some possibility that hepatoid differentiation exists in other regions of the colon tumor or in the liver tumor, parenchymal cells or lung metastases, which were composed of PIVKA-II-positive and AFP-negative cells.

CONCLUSION

To the best of our knowledge, high serum levels of PIVKA-II resulting from colon adenocarcinoma have not been reported previously. We report this rare case together with a review of the literature.

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.

A functional screening identifies five microRNAs controlling glypican-3: role of miR-1271 down-regulation in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the major primary liver cancer. Glypican-3 (GPC3), one of the most abnormally expressed genes in HCC, participates in liver carcinogenesis. Based on data showing that GPC3 expression is posttranscriptionally altered in HCC cells compared to primary hepatocytes, we investigated the implication of microRNAs (miRNAs) in GPC3 overexpression and HCC. To identify GPC3-regulating miRNAs, we developed a dual-fluorescence FunREG (functional, integrated, and quantitative method to measure posttranscriptional regulations) system that allowed us to screen a library of 876 individual miRNAs. Expression of candidate miRNAs and that of GPC3 messenger RNA (mRNA) was measured in 21 nontumoral liver and 112 HCC samples. We then characterized the phenotypic consequences of modulating expression of one candidate miRNA in HuH7 cells and deciphered the molecular mechanism by which this miRNA controls the posttranscriptional regulation of GPC3. We identified five miRNAs targeting GPC3 3'-untranslated region (UTR) and regulating its expression about the 876 tested. Whereas miR-96 and its paralog miR-1271 repressed GPC3 expression, miR-129-1-3p, miR-1291, and miR-1303 had an inducible effect. We report that miR-1271 expression is down-regulated in HCC tumor samples and inversely correlates with GPC3 mRNA expression in a particular subgroup of HCC. We also report that miR-1271 inhibits the growth of HCC cells in a GPC3-dependent manner and induces cell death.

CONCLUSION

Using a functional screen, we found that miR-96, miR-129-1-3p, miR-1271, miR-1291, and miR-1303 differentially control GPC3 expression in HCC cells. In a subgroup of HCC, the up-regulation of GPC3 was associated with a concomitant down-regulation of its repressor miR-1271. Therefore, we propose that GPC3 overexpression and its associated oncogenic effects are linked to the down-regulation of miR-1271 in HCC.

An introduction to proteoglycans and their localization

Proteoglycans comprise a core protein to which one or more glycosaminoglycan chains are covalently attached. Although a small number of proteins have the capacity to be glycanated and become proteoglycans, it is now realized that these macromolecules have a range of functions, dependent on type and in vivo location, and have important roles in invertebrate and vertebrate development, maintenance, and tissue repair. Many biologically potent small proteins can bind glycosaminoglycan chains as a key part of their function in the extracellular matrix, at the cell surface, and also in some intracellular locations. Therefore, the participation of proteoglycans in disease is receiving increased attention. In this short review, proteoglycan structure, function, and localizations are summarized, with reference to accompanying reviews in this issue as well as other recent literature. Included are some remarks on proteoglycan and glycosaminoglycan localization techniques, with reference to the special physicochemical properties of these complex molecules.

Overexpression of the structural maintenance of chromosome 4 protein is associated with tumor de-differentiation, advanced stage and vascular invasion of primary liver cancer

Structural maintenance of chromosome 4 (SMC4) is associated with tumorigenesis. The present study aimed at detecting SMC4 expression in primary liver cancer and its association with clinicopathological patient data. A total of 72 primary liver cancer tissues and 6 liver cell lines were assessed for expression of SMC4 mRNA and protein with qRT-PCR, western blotting and immunohistochemistry, respectively. SMC4 siRNAs were constructed to knockdown SMC4 expression, and phenotypic changes of hepatocellular carcinoma (HCC) cells were analyzed using flow cytometry and cell viability assays. The data showed that SMC4 mRNA and protein were highly expressed in HCC tissues compared to the normal tissues. Immunohistochemical analysis revealed that 52 of 72 (72.2%) paraffin-embedded primary liver cancer tissues displayed strong cytoplasmic staining of SMC4 protein, whereas only 6 (8.3%) normal liver tissues showed immunostaining of SMC4. Statistical analysis showed that SMC4 expression was significantly associated with tumor size, de-differentiation, advanced stages and vascular invasion of the primary liver cancers. Moreover, knockdown of SMC4 expression reduced HCC cell proliferation. These data demonstrated that expression of SMC4 protein may be useful for the early detection and prediction of primary liver cancer progression.

High-affinity monoclonal antibodies to cell surface tumor antigen glypican-3 generated through a combination of peptide immunization and flow cytometry screening

Isolating high-affinity antibodies against native tumor antigens on the cell surface is not straightforward using standard hybridoma procedures. Here, we describe a combination method of synthetic peptide immunization and high-throughput flow cytometry screening to efficiently isolate hybridomas for cell binding. Using this method, we identified high-affinity monoclonal antibodies specific for the native form of glypcian-3 (GPC3), a target heterogeneously expressed in hepatocellular carcinoma (HCC) and other cancers. We isolated a panel of monoclonal antibodies (YP6, YP7, YP8, YP9 and YP9.1) for cell surface binding. The antibodies were used to characterize GPC3 protein expression in human liver cancer cell lines and tissues by flow cytometry, immunoblotting and immunohistochemistry. The best antibody (YP7) bound cell surface-associated GPC3 with equilibrium dissociation constant, KD = 0.3 nmol/L and was highly specific for HCC, not normal tissues or other forms of primary liver cancers (such as cholangiocarcinoma). Interestingly, the new antibody was highly sensitive in that it detected GPC3 in low expression ovarian clear cell carcinoma and melanoma cells. The YP7 antibody exhibited significant HCC xenograft tumor growth inhibition in nude mice. These results describe an improved method for producing high-affinity monoclonal antibodies to cell surface tumor antigens and represent a general approach to isolate therapeutic antibodies against cancer. The new high-affinity antibodies described here have significant potential for GPC3-expressing cancer diagnostics and therapy.