• CD44
• Cancer
• Metastasis
• Osteopontin

• Humans
• Bone and Bones/metabolism
• Neoplasms
• Osteopontin/metabolism
• Signal Transduction

• MPM (malignant pleural mesothelioma)
• immune system and cancer
• immunotherapy
• novel therapeutic approach
• osteopontin (OPN)

Osteopontin (OPN) is involved in vascular calcification and atherosclerosis. We evaluated the association between serum OPN levels and the first postoperative hospitalization and all-cause mortality in patients who received kidney transplantation (KT).

Seventy KT recipients were enrolled in this study from January to April 2012. The primary end point was first postoperative hospitalization or death. All patients were monitored in the outpatient clinics until June 30, 2017. Serum OPN level was measured by enzyme-linked immunosorbent assay.

During follow-up (median length, 65 months), 47 first postoperative hospitalizations and 8 deaths occurred. In comparison with serum median OPN levels, serum OPN level was positively associated with KT duration (P = 0.048), serum blood urea nitrogen (BUN; P = 0.043), and serum creatinine levels (P = 0.045) but negatively associated with estimated glomerular filtration rate (eGFR; P = 0.049). Hospitalized KT recipients had a higher prevalence of diabetes mellitus (DM) (P = 0.032), BUN (P = 0.002), and serum OPN level (P = 0.001) but lower eGFR (P = 0.030) than did patients not hospitalized. KT recipients who died had higher serum level of creatinine (P = 0.009) and OPN (P = 0.001) but lower eGFR (P = 0.036) than did surviving patients. Multivariate Cox analysis adjusted for age, gender, DM, hypertension, eGFR, KT duration, and steroid used showed that serum OPN level was associated with both first postoperative hospitalization (P = 0.049) and all-cause mortality (P = 0.017).

Serum OPN level is a potential biomarker for first postoperative hospitalization and all-cause mortality in KT recipients.

• Aptamer
• Aptasensor
• Biosensor
• Breast cancer
• Chemotherapy
• Nanomedicine
• Nanoparticle
• SELEX
• siRNA
• targeted therapy

• Cirrhosis
• Hepatocellular cancer
• Liver fibrosis
• Non-alcoholic fatty liver disease
• Osteopontin
• Portal hypertension

• Immunomodulation
• Osteopontin
• Rejection
• Transplantation

• Biomarkers/blood
• Graft Rejection/blood
• Graft Rejection/diagnosis
• Graft Rejection/epidemiology
• Graft Rejection/immunology
• Graft vs Host Disease/blood
• Graft vs Host Disease/diagnosis
• Graft vs Host Disease/epidemiology
• Graft vs Host Disease/immunology
• Hematopoietic Stem Cell Transplantation/adverse effects
• Humans
• Organ Transplantation/adverse effects
• Osteopontin/blood
• Osteopontin/immunology
• Risk Assessment/methods

The molecular mechanisms of adrenocortical carcinoma development are incompletely defined. De-regulation of cellular-to-extracellular matrix interactions and angiogenesis appear among mechanisms associated to the malignant phenotype. Our aim was to investigate, employing PCR-based array profiling, 157 molecules involved in cell-to-matrix interactions and angiogenesis in a frozen series of 6 benign and 6 malignant adrenocortical neoplasms, to identify novel pathogenetic markers. In 14 genes, a significant dysregulation was detected in adrenocortical carcinomas as compared to adenomas, most of them being downregulated. Three exceptions—hyaluronan synthase 1 (HAS-1), laminin α3 and osteopontin genes—demonstrated an increased expression in adrenocortical carcinomas of 4.46, 4.23 and 20.32-fold, respectively, and were validated by immunohistochemistry on a series of paraffin-embedded tissues, including 20 adenomas and 73 carcinomas. Osteopontin protein, absent in all adenomas, was expressed in a carcinoma subset (25/73) (p = 0.0022). Laminin α3 and HAS-1 were mostly expressed in smooth muscle and endothelial cells of the vascular network of both benign and malignant adrenocortical tumors. HAS-1 was also detected in tumor cells, with a more intense pattern in carcinomas. In this group, strong expression was significantly associated with more favorable clinicopathological features. These data demonstrate that cell-to-matrix interactions are specifically altered in adrenocortical carcinoma and identify osteopontin and HAS-1 as novel potential diagnostic and prognostic biomarkers, respectively, in adrenal cortical tumors.

• adrenal cortex
• angiogenesis
• carcinoma
• gene expression
• hyaluronan synthase 1
• osteopontin

• ALCL
• HSP90
• osteopontin
• proteomics
• small EVs
• tenascin C

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.

• HCC
• anti-fibrotic
• desmoplastic stroma
• extracellular matrix (ECM)
• immune suppression
• nanoparticle
• platelet-derived growth factor (PDGF)
• siRNA
• therapy
• tumor microenvironment (TME)
• tumor-associated-macrophage (TAM)

Hepatocellular carcinoma (HCC) is one of the most prevalent neoplasms worldwide, particularly in China. Immune-related genes (IRGs) and immune infiltrating lymphocytes play specific roles in tumor growth. Considering how important immunotherapy has become for HCC treatment in the past decade, our objective was to establish a prognostic model by screening survival-related IRGs in patients with HCC. Using edgeR, we identified differentially expressed IRGs (DEIRGs), DEmiRNAs, and DElncRNAs. Functional enrichment analysis of DEIRGs was performed to investigate the biological functions of IRGs via gene ontology annotation and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses. Protein-protein interaction and competing endogenous RNA networks were established using Cytoscape. Survival-associated IRGs were selected via univariate COX regression analysis, a The Cancer Genome Atlas (TCGA) prognostic model and GSE76427 validation model were developed using multivariate COX regression analysis test by AIC (Akaike Information Criterion). We identified 116 DEIRGs in patients with HCC; the “cytokine-cytokine receptor interaction” pathway was found to be the most enriched pathway. Via the prognostic model helped us classify patients into high- and low-risk score groups based on overall survival (OS); high risk score was associated with worse OS, and a positive correlation was observed between the prognostic model and immune cell infiltration. To summarize, we established a prognostic model using survival-related IRGs that provides sufficient information for prognosis prediction and immunotherapy of patients with HCC.

• The Cancer Genome Atlas (TCGA)
• ceRNA network
• hepatocellular carcinoma
• immune-related genes
• prognostic model

• Aptamer
• Aptasensor
• Cancer biomarker
• Human osteopontin
• Lateral flow assay

• HCC
• Mdr2
• Ntrk2
• S100a4
• Spp1

• Alternative Splicing
• Animals
• Cell Division
• Chronic Disease
• Cocarcinogenesis
• Female
• Galectin 1/deficiency
• Galectin 1/genetics
• Galectin 1/physiology
• Hep G2 Cells
• Hepatitis/genetics
• Hepatitis/metabolism
• Hepatitis/pathology
• Hepatocytes/pathology
• Humans
• Liver Cirrhosis/genetics
• Liver Cirrhosis/metabolism
• Liver Cirrhosis/pathology
• Liver Neoplasms, Experimental/etiology
• Liver Neoplasms, Experimental/genetics
• Liver Neoplasms, Experimental/metabolism
• Liver Neoplasms, Experimental/pathology
• Male
• Membrane Glycoproteins/biosynthesis
• Membrane Glycoproteins/genetics
• Mice
• Mice, Inbred C57BL
• Mice, Inbred Strains
• Mice, Knockout
• Neoplasm Proteins/genetics
• Neoplasm Proteins/metabolism
• Osteopontin/biosynthesis
• Osteopontin/deficiency
• Osteopontin/genetics
• Precancerous Conditions/genetics
• Precancerous Conditions/metabolism
• Precancerous Conditions/pathology
• Protein-Tyrosine Kinases/biosynthesis
• Protein-Tyrosine Kinases/genetics
• Specific Pathogen-Free Organisms

• R01 CA197081 NCI NIH HHS
• Agencia Nacional de Promoción Científica y Tecnológica
• Fundación Bunge & Born and the Kenneth Rainin Foundation
• U.S. National Institutes of Health
• National Cancer Institute
• Ministry Of Science and Technology
• Israeli Science Foundation (ISF) collaboration with Canada
• Israeli Centers Of Research Excellence (ICORE)–ISF
• Deutsche Forschungsgemeinschaft

• Osteopontin
• Pokémon
• fibrosis
• hepatitis C virus (HCV)
• hepatocellular carcinoma (HCC)

Correlation of osteopontin (OPN) gene expression with proliferation and apoptosis of ovarian cancer cells and prognosis of patients was investigated. The expression levels of OPN in 81 pairs of ovarian cancer tissues and para-carcinoma tissues obtained via surgical resection were detected using immunohistochemistry (IHC). The correlation of OPN protein expression with clinicopathological features of patients was analyzed. All patients were followed up for 3 years. The disease-free survival (DFS) and overall survival (OS) curves of patients in high/low OPN expression groups were drawn using the Kaplan-Meier method. The expression levels of OPN in normal ovarian epithelial IOSE80 cells and 5 ovarian cancer cell lines were detected via western blotting. Moreover, two cell lines with high OPN expression were interfered with lentiviral transfection technique. The effects of OPN on ovarian cancer cell proliferation and apoptosis were detected and analyzed via Cell Counting Kit-8 (CCK8) assay and flow cytometry. The positive expression rate of OPN protein in tumor tissues was higher than that in para-carcinoma tissues (P<0.05). Survival curves suggested that both DFS and OS in OPN negative group were superior to those in OPN positive group (P<0.05). Results of western blotting showed that OPN was weakly expressed in IOSE80 cells, whereas it was highly expressed in SKOV-3, COC1, A2780, HO-8910 and OVCAR-3 cells, among which the OPN protein expression levels were relatively higher in SKOV-3 and OVCAR-3 cell lines. After knockdown of OPN gene with sh-OPN, the cell proliferation rates of OVCAR-3 and SKOV-3 were significantly decreased from 48 h (P<0.05), but the apoptosis level was increased remarkably (28.2 vs. 1.3% and 25.3 vs. 3.2%), and differences were statistically significant (P<0.05). In conclusion, overexpression of OPN enhances the proliferation of ovarian cancer cells, which is an adverse factor for patient survival and prognosis.

• OPN
• apoptosis
• ovarian cancer
• prognosis
• proliferation

Osteopontin (OPN) is a bone sialoprotein involved in osteoclast attachment to mineralised bone matrix, as well as being a bone matrix protein, OPN is also a versatile protein that acts on various receptors which are associated with different signalling pathways implicated in cancer. OPN mediates various biological events involving the immune system and the vascular system; the protein plays a role in processes such as immune response, cell adhesion and migration, and tumorigenesis. This review discusses the potential role of OPN in tumour cell proliferation, angiogenesis and metastasis, as well as the molecular mechanisms involved in these processes in different cancers, including brain, lung, kidney, liver, bladder, breast, oesophageal, gastric, colon, pancreatic, prostate and ovarian cancers. The understanding of OPN’s role in tumour development and progression could potentially influence cancer therapy and contribute to the development of novel anti-tumour treatments.

Osteopontin (OPN), a phosphorylated glycoprotein, is frequently overexpressed in cancer. Among the three OPN isoforms, OPN-a is the most highly expressed in lung cancer cell lines and lung tumors. Overexpression of OPN-a greatly reduced CL1-5 lung adenocarcinoma cell growth, but had no effect on growth in A549 lung adenocarcinoma cells. Examination of the expression of integrins and CD44, which are possible OPN-a receptors, revealed that differences in integrin β3 levels might explain this discrepancy between CL1-5 and A549 cells. When integrin β3 was ectopically expressed in A549 cells, OPN-a inhibited their growth, whereas OPN-a increased cell growth following integrin β3 knockdown in CL1-5 cells. This OPN-a-induced increase in growth appeared to result from activation of the CD44/NFκB pathway. Our results demonstrated that OPN-a inhibits growth of cells with high integrin β3 levels and increases growth via activation of the CD44/NFκB pathway in cells with low integrin β3 levels. Thus, OPN-a, integrin β3, and CD44 interact to affect lung cancer cell growth, and this study may aid in the development of cancer treatment strategies involving these molecules.

• CD44
• NF-kB
• OPN-a
• integrin β3

• de novo lipogenesis
• glycerolipids
• nonalcoholic fatty liver disease

Hepatocellular carcinoma (HCC) is the third leading cause of cancer-related death worldwide. Chronic hepatitis B virus (HBV) infection is a major cause for HCC. Hepatitis B virus X (HBx), one of four proteins encoded by HBV genome, plays a vital role in the pathogenesis of HBV-induced HCC. However, the molecular mechanisms of HBx-triggered HCC remain largely undetermined. Here we revealed that the expression of Brain-expressed X-linked 2 (BEX2) and Osteopontin (OPN) were elevated in liver tissues of HBV transgenic mice and human HCC specimens. Moreover, a positive correlation between BEX2 and OPN was exhibited in samples from HCC patients with HBV infection. The protein levels of BEX2 and OPN were both higher in HBV-positive HCC specimens compared to that of HBV-negative HCC specimens. HBx potentiated OPN expression through up-regulation of BEX2. Importantly, the depletion of BEX2 suppressed tumorigenic potential of HCC cells with highly expressed HBx. We demonstrated the important role of BEX2 in HCC pathogenesis, and BEX2 may be a novel therapeutic target for HCC patients with HBV infection. The newly identified HBx/BEX2/OPN signaling cassette is implicated in the pathogenesis of HBV-induced HCC.

• BEX2
• HBV
• HBx
• HCC
• osteopontin

Complex interactions between tumor and host cells regulate systemic tumor dissemination, a process that begins early at the primary tumor site and goes on until tumor cells detach themselves from the tumor mass and start migrating into the blood or lymphatic vessels. Metastatic cells colonize the target organs and are capable of surviving and growing at distant sites. In this context, osteopontin (OPN) appears to be a key determinant of the crosstalk between cancer cells and the host microenvironment, which in turn modulates immune evasion. OPN is overexpressed in several human carcinomas and has been implicated in inflammation, tumor progression, and metastasis. Thus, it represents one of the most attracting targets for cancer therapy. Within the tumor mass, OPN is secreted in various forms either by the tumor itself or by stroma cells, and it can exert either pro- or antitumorigenic effects according to the cell type and tumor microenvironment. Thus, targeting OPN for therapeutic purposes needs to take into account the heterogeneous functions of the multiple OPN forms with regard to cancer formation and progression. In this review, we will describe the role of systemic, tumor-derived, and stroma-derived OPN, highlighting its pivotal role at the crossroads of inflammation and tumor progression.

• Bispecific antibody
• Chimeric antigen receptor
• Hepatocellular carcinoma
• Treatment

• Animals
• Antibodies, Bispecific/adverse effects
• Antibodies, Bispecific/therapeutic use
• Antibody Specificity
• Antigens, Neoplasm/immunology
• Antineoplastic Agents/adverse effects
• Antineoplastic Agents/therapeutic use
• Carcinoma, Hepatocellular/drug therapy
• Carcinoma, Hepatocellular/immunology
• Carcinoma, Hepatocellular/pathology
• Cell Death/drug effects
• Cytotoxicity, Immunologic
• Humans
• Immunotherapy/adverse effects
• Immunotherapy/methods
• Liver Neoplasms/drug therapy
• Liver Neoplasms/immunology
• Liver Neoplasms/pathology
• Receptors, Antigen/immunology
• Recombinant Fusion Proteins/adverse effects
• Recombinant Fusion Proteins/therapeutic use
• Signal Transduction/drug effects

• P30 CA008748 NCI NIH HHS

Osteopontin (Opn), a multifunctional extracellular matrix protein, is implicated in the pathogenesis of various inflammatory disorders. Under physiologic conditions, its expression is restricted to certain tissues including bone and kidney tubule. However, cellular activation during disease development induces Opn expression in various immune cells. In this study, using Opn-EGFP knock-in (KI) mice we found that CD8α⁺ T cells in the intestinal tissues, including Peyer’s patch, lamina propria and epithelium, express Opn under steady state conditions. Therefore, we examined the role of Opn-expressing CD8α⁺ T cells in intestinal homeostasis. Interestingly, Opn knockout (KO) mice had altered fecal microflora concordant with a reduction of TCRγδ⁺ intraepithelial lymphocytes (IELs). Consistent with this result, both treatment with anti-Opn blocking antibody and deficiency of Opn resulted in decreased survival of TCRγδ⁺ and TCRαβ⁺ IELs. This data suggests that a possibility that Opn may function as a survival factor for IELs in the intestinal tissue. Collectively, these data suggest the possibility that Opn might regulate the homeostasis of intestinal microflora through maintenance of TCRγδ⁺ IELs, possibly by support of IEL survival.

• Animals
• Bacterial Physiological Phenomena
• Gene Expression Profiling
• Homeostasis/physiology
• Intestines/microbiology
• Mice
• Mice, Transgenic
• Osteopontin/physiology

• Astellas Pharma Inc. in the Creation of Innovation Centers for Advanced Interdisciplinary Research Areas Program
• Japan Societies for the Promotion of Sciences, Grant-in-Aid for Young Scientists (B)

• Osteopontin
• chronic non-hereditary pancreatitis
• pancreatic ductal adenocarcinoma
• type 2 diabetes mellitus

• B-cell lymphomas
• Interleukin-6
• Matrixmetalloproteinase
• Osteopontin

• Aged
• Area Under Curve
• Biomarkers/blood
• Female
• Hepatitis C, Chronic/blood
• Hepatitis C, Chronic/pathology
• Humans
• Liver Cirrhosis/blood
• Liver Cirrhosis/pathology
• Liver Cirrhosis/virology
• Male
• Middle Aged
• Osteopontin/blood
• ROC Curve
• Severity of Illness Index

Nowadays it is perfectly clear that understanding and eradicating cancer cell invasion and metastasis represent the crucial, definitive points in cancer therapeutics. During the last two decades there has been a great interest in the understanding of the extracellular molecular mechanisms involved in cancer cell invasion. In this review, we highlight the findings concerning these processes, focusing in particular on extracellular molecules, including extracellular matrix proteins and their receptors, growth factors and their receptors, matrix metalloproteinases and extracellular chaperones. We report the molecular mechanisms underlying the important contribution of this pool of molecules to the complex, multi-step phenomenon of cancer cell invasion.

• Hepatitis C virus
• Hepatocellular carcinoma
• Osteopontin

• Animals
• Carcinoma, Hepatocellular/diagnostic imaging
• Carcinoma, Hepatocellular/drug therapy
• Carcinoma, Hepatocellular/pathology
• Cell Line, Tumor
• Cell Proliferation/drug effects
• Disease Models, Animal
• Doxorubicin/pharmacology
• Doxorubicin/therapeutic use
• Drug Evaluation/instrumentation
• Liver Neoplasms/diagnostic imaging
• Liver Neoplasms/drug therapy
• Liver Neoplasms/pathology
• Mice
• Mice, Inbred C57BL
• Robotics
• X-Ray Microtomography
• Xenograft Model Antitumor Assays

• Carcinoma, Hepatocellular/metabolism
• Carcinoma, Hepatocellular/pathology
• Carcinoma, Hepatocellular/virology
• Epithelial-Mesenchymal Transition
• Gene Expression Regulation, Neoplastic
• Hep G2 Cells
• Hepacivirus/metabolism
• Hepatitis C, Chronic/metabolism
• Hepatitis C, Chronic/pathology
• Hepatocytes/metabolism
• Hepatocytes/pathology
• Hepatocytes/virology
• Humans
• Hyaluronan Receptors
• Liver Neoplasms/metabolism
• Liver Neoplasms/pathology
• Liver Neoplasms/virology
• Neoplasm Proteins/biosynthesis
• Osteopontin/biosynthesis
• Signal Transduction

• R56 AI089772 NIAID NIH HHS
• 1R56AI089772-01A1 NIAID NIH HHS

• alcoholic liver disease
• hepatocellular carcinoma
• liver fibrosis
• non-alcoholic fatty liver disease
• osteopontin

α-Fetoprotein (AFP) is the biomarker most widely used to detect hepatocellular carcinoma (HCC), despite its suboptimal diagnostic accuracy. Glypican-3 (GPC3) and osteopontin (OPN) are secreted glycoproteins that are reportedly associated with tumorigenesis and metastasis. This study was conducted to evaluate the clinical utility of using plasma GPC3 and OPN as diagnostic biomarkers for HCC.

We measured the plasma levels of GPC3 and OPN in 120 HCC and 40 chronic liver disease (CLD) patients via an enzyme-linked immunosorbent assay. The diagnostic accuracy of each tumor marker was evaluated using receiver operating characteristic (ROC) curve analysis.

The GPC3 levels in the HCC patients (75.8 ng/mL) were significantly higher (p=0.020) than the levels in patients with CLD (66.4 ng/mL). The area under the ROC curve (AUROC) values for GPC3 and OPN were 0.62 and 0.51, respectively. In subgroup analyses, including subgroups of HCC patients with low serum AFP and PIVKA II levels, the AUROC of GPC3 remained relatively high (0.66), and GPC3 showed a high sensitivity (62.1%) for detecting small HCC tumors.

The plasma levels of GPC3 and OPN demonstrated low diagnostic accuracy for HCC. However, GPC3 may have a complementary role in diagnosing HCC in patients with nondiagnostic levels of conventional tumor markers and with small-sized tumors.

• Glypican-3
• Hepatocellular carcinoma
• Osteopontin

• Hepatocellular carcinoma
• Osteopontin
• SNPs
• SRY
• Sex difference

Gastric cancer and liver cancer are among the most common malignancies and the leading causes of death worldwide, due to late detection and high recurrence rates. Today, these cancers have a heavy socioeconomic burden, for which a full understanding of their pathophysiological features is warranted to search for promising biomarkers and therapeutic targets. Osteopontin (OPN) is overexpressed in most patients with gastric and liver cancers. Over the past decade, emerging evidence has revealed a correlation of OPN level and clinicopathological features and prognosis in gastric and liver cancers, indicating its potential as an independent prognostic indicator in such patients. Functional studies have verified the potential of OPN knockdown as a therapeutic approach in vitro and in vivo. Furthermore, OPN mediates multifaceted roles in the interaction between cancer cells and the tumor microenvironment, in which many details need further exploration. OPN signaling results in various functions, including prevention of apoptosis, modulation of angiogenesis, malfunction of tumor-associated macrophages, degradation of extracellular matrix, activation of phosphoinositide 3-kinase-Akt and nuclear factor-κB pathways, which lead to tumor formation and progression, particularly in gastric and liver cancers. This editorial aims to review recent findings on alteration in OPN expression and its clinicopathological associations with tumor progression, its potential as a therapeutic target, and putative mechanisms in gastric and liver cancers. Better understanding of the implications of OPN in tumorigenesis might facilitate development of therapeutic regimens to benefit patients with these deadly malignancies.

• Osteopontin
• Gastrointestinal cancer
• Metastasis
• Prognosis
• Biomarker

AIM: To investigate the role of osteopontin (OPN) and its splice variants in the proliferation of hepatocellular carcinoma (HCC).

METHODS: The expression of OPN variants in HCC cell lines as well as HCC tissue samples and non-tumour tissue was studied using polymerase chain reaction. OPN variant cDNAs were cloned into a mammalian expression vector allowing both transient expression and the production of stable OPN expressing cell lines. OPN expression was studied in these cells using Western blotting, immunofluoresnce and enzyme linked immunosorbent assay. A CD44 blocking antibody and siRNA targeting of CD44 were used to examine the role of this receptor in the OPN stimulated cell growth observed in culture. Huh-7 cells stably expressing either OPN-A, -B or -C were injected subcutaneously into the flanks of nude mice to observe in vivo tumour growth. Expression of OPN mRNA and protein in these tumours was examined using reverse transcription-polymerase chain reaction and immunohistochemistry.

RESULTS: OPN is expressed in HCC in 3 forms, the full length OPN-A and 2 splice variants OPN-B and -C. OPN variant expression was noted in HCC tissue as well as cognate surrounding cirrhotic liver tissue. Expression of these OPN variants in the HCC derived cell line Huh-7 resulted in secretion of OPN into the culture medium. Transfer of OPN conditioned media to naïve Huh-7 and HepG2 cells resulted in significant cell growth suggesting that all OPN variants can modulate cell proliferation in a paracrine manner. Furthermore the OPN mediated increase in cellular proliferation was dependent on CD44 as only CD44 positive cell lines responded to OPN conditioned media while siRNA knockdown of CD44 blocked the proliferative effect. OPN expression also increased the proliferation of Huh-7 cells in a subcutaneous nude mouse tumour model, with Huh-7 cells expressing OPN-A showing the greatest proliferative effect.

CONCLUSION: This study demonstrates that OPN plays a significant role in the proliferation of HCC through interaction with the cell surface receptor CD44. Modulation of this interaction could represent a novel strategy for the control of HCC.

• Osteopontin
• Hepatocellular carcinoma
• CD44 antigen
• Nude mice
• Xenograft

• Arachidonate 5-Lipoxygenase/chemistry
• Arachidonate 5-Lipoxygenase/genetics
• Arachidonate 5-Lipoxygenase/metabolism
• Blotting, Western
• Calpain/antagonists & inhibitors
• Calpain/genetics
• Calpain/metabolism
• Carcinoma, Hepatocellular/genetics
• Carcinoma, Hepatocellular/metabolism
• Carcinoma, Hepatocellular/pathology
• Cell Movement/physiology
• Enzyme-Linked Immunosorbent Assay
• Feedback, Physiological
• Humans
• Liver Neoplasms/genetics
• Liver Neoplasms/metabolism
• Liver Neoplasms/pathology
• Luciferases/metabolism
• Osteopontin/antagonists & inhibitors
• Osteopontin/genetics
• Osteopontin/metabolism
• RNA, Messenger/genetics
• RNA, Small Interfering/genetics
• Real-Time Polymerase Chain Reaction
• Signal Transduction
• Trans-Activators/genetics
• Trans-Activators/metabolism
• Tumor Cells, Cultured
• Viral Regulatory and Accessory Proteins

• Adult
• Aged
• Biomarkers, Tumor/metabolism
• Carcinoma, Hepatocellular/metabolism
• Carcinoma, Hepatocellular/mortality
• Carcinoma, Hepatocellular/surgery
• Female
• Humans
• Liver Neoplasms/metabolism
• Liver Neoplasms/mortality
• Liver Neoplasms/surgery
• Liver Transplantation
• Male
• Middle Aged
• Multivariate Analysis
• Osteopontin/metabolism
• Prognosis
• Proportional Hazards Models
• Recurrence
• Survival Analysis