Down-regulation of osteopontin suppresses growth and metastasis of hepatocellular carcinoma via induction of apoptosis

Progesterone increases apoptosis and inversely decreases autophagy in human hepatoma HA22T/VGH cells treated with epirubicin

Hepatocellular carcinoma (HCC) is the leading cause of cancer-related deaths worldwide. Epirubicin can induce intracellular reactive oxygen species and is widely used to treat unresectable HCC. Progesterone has been found to inhibit the proliferation of hepatoma cells. This study was designed to test the combined effects of epirubicin and progesterone on human hepatoma cell line, HA22T/VGH. These cells were treated with different concentrations of epirubicin with or without the coaddition of 30 μM progesterone and then analyzed for apoptosis, autophagy, and expressions of apoptotic-related proteins and multidrug-resistant gene. Epirubicin treatment dose-dependently inhibited the growth of HA22T/VGH cells. Addition of 30 μM progesterone, which was inactive alone, augmented the effect of epirubicin on the inhibition of growth of HA22T/VGH cells. Cotreatment with progesterone enhanced epirubicin-induced apoptosis, as evidenced by greater increase in caspase-3 activity and in the ratio of the apoptosis-regulating protein, Bax/Bcl-X_L. The combination also caused a decrease in autophagy and in the expression of multidrug resistance-related protein 1 mRNA compared to epirubicin alone. This study shows the epirubicin/progesterone combination was more effective in increasing apoptosis and inversely decreasing autophagy on HA22T/VGH cells treated with epirubicin alone, suggesting that this combination can potentially be used to treat HCC.

Osteopontin and latent-TGF β binding-protein 2 as potential diagnostic markers for HBV-related hepatocellular carcinoma

Chronic Hepatitis B (HB) is the main risk factor for chronic liver disease (CLD) and hepatocellular carcinoma (HCC) in many low-resource countries, where diagnosis is constrained by lack of clinical, histopathological and biomarker resources. We have used proteomics to detect plasma biomarkers that outperform α-Fetoprotein (AFP), the most widely used biomarker for HCC diagnosis in low-resource contexts. Deep-plasma proteome analysis was performed in HCC patients, patients with CLD and in HB-carrier controls from Thailand (South-East Asia) and The Gambia (West-Africa). Mass spectrometry profiling identified latent-transforming growth factor β binding-protein 2 (LTBP2) and Osteopontin (OPN) as being significantly elevated in HCC versus CLD and controls. These two proteins were further analyzed by ELISA in a total of 684 plasma samples, including 183 HCC, 274 CLD and 227 asymptomatic controls. When combined, LTBP2 and OPN showed an area under the receiver operating curve of 0.85 in distinguishing HCC from CLD in subjects with AFP <20 ng/mL. In a prospective cohort of 115 CLD patients from Korea, increased plasma levels of LTBP2 and/or OPN were detected in plasma collected over 2 years prior to diagnosis in 21 subjects who developed HCC. Thus, the combination of LTBP2 and OPN outperformed AFP for diagnosis and prediction of HCC and may therefore improve biomarker-based detection of HBV-related HCC.

Osteopontin deficiency aggravates hepatic injury induced by ischemia-reperfusion in mice

Osteopontin (OPN) is a multifunctional protein involved in hepatic steatosis, inflammation, fibrosis and cancer progression. However, its role in hepatic injury induced by ischemia–reperfusion (I–R) has not yet been investigated. We show here that hepatic warm ischemia for 45 min followed by reperfusion for 4 h induced the upregulation of the hepatic and systemic level of OPN in mice. Plasma aspartate aminotransferase and alanine aminotransferase levels were strongly increased in Opn^−/− mice compared with wild-type (Wt) mice after I–R, and histological analysis of the liver revealed a significantly higher incidence of necrosis of hepatocytes. In addition, the expression levels of inducible nitric oxide synthase (iNOS), tumor necrosis factor-α (TNFα), interleukin 6 (IL6) and interferon-γ were strongly upregulated in Opn^−/− mice versus Wt mice after I–R. One explanation for these responses could be the vulnerability of the OPN-deficient hepatocyte. Indeed, the downregulation of OPN in primary and AML12 hepatocytes decreased cell viability in the basal state and sensitized AML12 hepatocytes to cell death induced by oxygen–glucose deprivation and TNFα. Further, the downregulation of OPN in AML12 hepatocytes caused a strong decrease in the expression of anti-apoptotic Bcl2 and in the ATP level. The hepatic expression of Bcl2 also decreased in Opn^−/− mice versus Wt mice livers after I–R. Another explanation could be the regulation of the macrophage activity by OPN. In RAW macrophages, the downregulation of OPN enhanced iNOS expression in the basal state and sensitized macrophages to inflammatory signals, as evaluated by the upregulation of iNOS, TNFα and IL6 in response to lipopolysaccharide. In conclusion, OPN partially protects from hepatic injury and inflammation induced in this experimental model of liver I–R. This could be due to its ability to partially prevent death of hepatocytes and to limit the production of toxic iNOS-derived NO by macrophages.

Osteopontin is a promoter for hepatocellular carcinoma metastasis: a summary of 10 years of studies

In this review, we summarize the novel findings from our series of studies on the leading metastasis-related gene, osteopontin (OPN). In our previous gene expression profiling study, OPN was identified as one of the leading genes associated with the metastasis of hepatocellular carcinoma (HCC). We focused on OPN to evaluate its prognostic values and important roles in HCC metastasis. A retrospective study of large cohorts of HCC patients demonstrated that plasma OPN level was one of the leading independent prognostic factors for HCC patients, even in the early stage of HCC, and could serve as a surrogate serologic biomarker for monitoring the treatment response and tumor recurrence after HCC resection. Using both in vitro and in vivo investigations, we found that OPN has an important role in metastasis and tumor growth of HCC and is an attractive potential therapeutic target for combating HCC metastasis. We also found that OPN⁺ HCC cells have much more amplifications at chromosomal regions, and promoter polymorphisms are important in the regulation of OPN expression and tumor growth and lung metastasis of HCC.

Osteopontin promotes the invasive growth of melanoma cells by activating integrin αvβ3 and down-regulating tetraspanin CD9

Overexpression of osteopontin (OPN) is strongly associated with the invasiveness/metastasis of many cancers, including melanomas. However, the molecular mechanisms of OPN in these processes remain poorly understood. We found that forced expression of OPN in early vertical-growth-phase melanoma cells dramatically increased their migration/invasion and growth/survival in a three-dimensional collagen I gel. Neutralizing antibodies to OPN, integrin β1, and integrin αvβ3, but not to CD44, negated the effects of OPN. Conversely, knocking down OPN in metastatic melanoma cells abrogated the invasive growth. OPN overexpression activated and OPN knockdown inactivated αvβ3 and αvβ5 integrins, negligibly affecting their expression. We further found OPN expression to inversely correlate with tetraspanin CD9 expression. Early-stage melanoma cells displayed low OPN and high CD9 expression, and conversely, metastatic cells displayed high OPN and low CD9 expression. Overexpression of OPN in vertical-growth-phase melanoma cells induced down-regulation of CD9, and knockdown of OPN in metastatic melanoma cells up-regulated CD9. Reversion of these CD9 changes abolished the effects of OPN. Furthermore, knockdown of CD9 in early-stage melanoma cells stimulated their invasive capacity in three-dimensional collagen. Similarly, microarray analyses of benign nevi and primary melanomas from different stages revealed an inverse correlation between OPN and CD9. These data suggest that OPN promotes melanoma cell invasion by activating integrin αvβ3 and down-regulating CD9, a putative metastasis suppressor.

SM5-1-conjugated PLA nanoparticles loaded with 5-fluorouracil for targeted hepatocellular carcinoma imaging and therapy

SM5-1 is a humanized mouse antibody which has a high binding specificity for a membrane protein of about 230 kDa overexpressed in hepatocellular carcinoma (HCC), melanoma and breast cancer. In this study, SM5-1-conjugated poly D, L (lactide-coglycolide) (PLA) PLA containing Cy7 (PLA-Cy7-SM5-1) was prepared to study the targeting specificity of the bioconjugate to HCC-LM3-fLuc cell. Then, SM5-1-conjugated PLA containing 5-fluorouracil (5-FU) (PLA-5FU-SM5-1) and PLA containing 5-FU (PLA-5FU) were prepared for treatment of subcutaneous HCC-LM3-fLuc tumor mice. The results showed that PLA-5FU-SM5-1, PLA-5FU and 5-FU induced a 45.07%, 23.56% and 19.05% tumor growth inhibition rate, respectively, on day 31 post-treatment as determined by bioluminescent intensity. In addition, in order to evaluate the antitumor efficacy of PLA-5FU-SM5-1, HCC-LM3-fLuc cells were injected into the liver to establish the experimental orthotopic liver tumor models. The experiments showed that PLA-5FU-SM5-1, PLA-5FU and 5-FU induced a 53.24%, 31.00%, and 18.11% tumor growth inhibition rate, respectively, on day 31 post-treatment determined by the bioluminescent intensity of the abdomen in tumor-bearing mice. Furthermore, we have calculated the three-dimensional location of the liver cancer in mice using a multilevel adaptive finite element algorithm based on bioluminescent intensity decay calibration. The reconstruction results demonstrated that PLA-5FU-SM5-1 inhibited the tumor rapid progression, which were consistent with the results of subcutaneous tumor mice experiments and in vitro cell experiment results.

Osteopontin: Versatile modulator of liver diseases

Osteopontin (OPN) is a multifunctional protein, involved in pathological conditions including inflammation, immunity, angiogenesis, fibrosis and cancer progression in various tissues. Hepatic inflammation and fibrosis induced by feeding with a diet deficient in methionine and choline (MCD diet) were markedly attenuated in OPN knockout mice when compared with wild-type mice in the model of non-alcoholic steatohepatitis (NASH). Hepatic cholangiocytes, myofibroblastic stellate cells and natural killer T cells were suggested to secret OPN in mice fed an MCD diet. Plasma and hepatic OPN levels were significantly higher in patients with NASH with advanced fibrosis than in those with early fibrosis. Hepatic OPN mRNA level was correlated with hepatic neutrophil infiltration and fibrosis in patients with alcoholic liver diseases. In those with hepatocellular carcinoma (HCC), OPN levels in plasma and HCC were prognostic factors after liver resection or transplantation. Downregulation of OPN inhibited tumor growth and lung metastasis in nude mice implanted with HCC cells. The single nucleotide polymorphism in the promoter region of the OPN gene was shown to be associated with activity of hepatitis in chronic hepatitis C patients, prognosis in patients with HCC, and growth and lung metastasis of HCC xenografts in nude mice. OPN was reported to be a downstream effecter of Hedgehog pathway, which modulates hepatic fibrosis and carcinogenesis. This review focuses on the roles of OPN in hepatic inflammation, fibrosis and cancer progression. Further elucidation of cellular interactions and molecular mechanisms associated with OPN actions may contribute to development of novel strategies for treatment of the liver diseases.

Osteopontin is associated with decreased apoptosis and αv integrin expression in lung adenocarcinoma

Osteopontin (OPN) is a glycoprotein involved in invasion, progression and metastasis of many carcinomas. It contains several functional domains including binding sites for αv integrins, cell surface molecules playing a major role in mediating cell migration and adhesion. The aim of the study was to evaluate the expression of osteopontin in human non-small cell lung cancer (NSCLC) and to determine its possible prognostic significance as well as relation to apoptosis and αv integrin expression. We analyzed 111 surgically resected NSCLC for immunohistochemical expression of OPN and αv integrin. OPN expression was compared to apoptotic rate and clinicopathological parameters such as tumor size, histological grade, lymph node status, pT, and TNM stage. Apoptotic rate was measured by TUNEL staining method. OPN expression in NSCLC was significantly higher in lung adenocarcinomas (AC) then in squamous cell carcinomas (p<0.001). There was no correlation between OPN expression and clinicopathological parameters. The level of OPN expression in AC was associated with decreased apoptotic activity of tumor cells (p=0.006), and correlated with αv integrin expression (p=0.048), particularly in low stage tumors (p=0.013). Prolonged tumor cell survival in lung AC due to OPN and αv integrin overexpression may have an impact on tumor progression and resistance to therapy.

Molecular profiling of stroma identifies osteopontin as an independent predictor of poor prognosis in intrahepatic cholangiocarcinoma

Intrahepatic cholangiocarcinoma (ICC) is the second most common type of primary cancer in the liver. ICC is an aggressive cancer with poor prognosis and limited therapeutic strategies. The identification of new drug targets and prognostic biomarkers is an important clinical challenge for ICC. The presence of an abundant stroma is a histological hallmark of ICC. Given the well-established role of the stromal compartment in the progression of cancer diseases, we hypothesized that relevant biomarkers could be identified by analyzing the stroma of ICC. By combining laser capture microdissection and gene expression profiling, we demonstrate that ICC stromal cells exhibit dramatic genomic changes. We identified a signature of 1,073 nonredundant genes that significantly discriminate the tumor stroma from nontumor fibrous tissue. Functional analysis of differentially expressed genes demonstrated that up-regulated genes in the stroma of ICC were related to cell cycle, extracellular matrix, and transforming growth factor beta (TGFβ) pathways. Tissue microarray analysis using an independent cohort of 40 ICC patients validated at a protein level the increased expression of collagen 4A1/COL4A1, laminin gamma 2/LAMC2, osteopontin/SPP1, KIAA0101, and TGFβ2 genes in the stroma of ICC. Statistical analysis of clinical and pathological features demonstrated that the expression of osteopontin, TGFβ2, and laminin in the stroma of ICC was significantly correlated with overall patient survival. More important, multivariate analysis demonstrated that the stromal expression of osteopontin was an independent prognostic marker for overall and disease-free survival.

CONCLUSION

The study identifies clinically relevant genomic alterations in the stroma of ICC, including candidate biomarkers for prognosis, supporting the idea that tumor stroma is an important factor for ICC onset and progression.

Loss of exon 4 in a human T-cell factor-4 isoform promotes hepatic tumourigenicity

BACKGROUND

T-cell factor (TCF) proteins represent key transcription factors that activate Wnt/β-catenin signalling. We have reported that a pair of TCF-4 isoforms (TCF-4C and TCF-4D) exhibit differential TCF transcriptional activity in hepatocellular carcinoma (HCC) cells, although their structure differs by only the presence (TCF-4D) or absence (TCF-4C) of exon 4.

AIM

To demonstrate a regulatory role of exon 4 in HCC development.

METHODS

TCF-4C and TCF-4D expression profiles were examined in 27 pairs of human HCC and adjacent liver tissues. The functional role of the TCF-4 isoforms was evaluated in OUMS-29 (an immortalized hepatocyte-derived) and HAK-1A (a well-differentiated HCC) cell lines using stable clones overexpressing the TCF-4 isoforms.

RESULTS

TCF-4C was significantly upregulated in HCC tissues compared with corresponding peritumour and normal liver tissues; in contrast, there was no difference in TCF-4D expression. TCF-4C clones derived from both cell lines exhibited increased TCF activity, Wnt-responsive target genes, cell proliferation, cell cycle progression and resistance to chemotherapeutic drugs compared with TCF-4D clones. Capability of cell migration and colony formation was significantly higher in TCF-4C than TCF-4D clones. In a nude mice xenograft model, the HAK-1A-derived TCF-4C clone rapidly developed tumours compared with the TCF-4D clone. TCF-4C clone-derived tumours exhibited upregulation of Wnt-responsive target genes compared with the slow developing and small TCF-4D-derived tumours.

CONCLUSION

These results demonstrate that the TCF-4C isoform lacking exon 4 is associated with a malignant phenotype compared with the exon 4-harbouring TCF-4D isoform, indicating that exon 4 of TCF-4 plays a prominent role in HCC development.

Pleiotropic effects of methionine adenosyltransferases deregulation as determinants of liver cancer progression and prognosis

Downregulation of liver-specific MAT1A gene, encoding S-adenosylmethionine (SAM) synthesizing isozymes MATI/III, and upregulation of widely expressed MAT2A, encoding MATII isozyme, known as MAT1A:MAT2A switch, occurs in hepatocellular carcinoma (HCC). Being inhibited by its reaction product, MATII isoform upregulation cannot compensate for MATI/III decrease. Therefore, MAT1A:MAT2A switch contributes to decrease in SAM level in rodent and human hepatocarcinogenesis. SAM administration to carcinogen-treated rats prevents hepatocarcinogenesis, whereas MAT1A-KO mice, characterized by chronic SAM deficiency, exhibit macrovesicular steatosis, mononuclear cell infiltration in periportal areas, and HCC development. This review focuses upon the pleiotropic changes, induced by MAT1A/MAT2A switch, associated with HCC development. Epigenetic control of MATs expression occurs at transcriptional and post-transcriptional levels. In HCC cells, MAT1A/MAT2A switch is associated with global DNA hypomethylation, decrease in DNA repair, genomic instability, and signaling deregulation including c-MYC overexpression, rise in polyamine synthesis, upregulation of RAS/ERK, IKK/NF-kB, PI3K/AKT, and LKB1/AMPK axis. Furthermore, decrease in MAT1A expression and SAM levels results in increased HCC cell proliferation, cell survival, and microvascularization. All of these changes are reversed by SAM treatment in vivo or forced MAT1A overexpression or MAT2A inhibition in cultured HCC cells. In human HCC, MAT1A:MAT2A and MATI/III:MATII ratios correlate negatively with cell proliferation and genomic instability, and positively with apoptosis and global DNA methylation. This suggests that SAM decrease and MATs deregulation represent potential therapeutic targets for HCC. Finally, MATI/III:MATII ratio strongly predicts patients' survival length suggesting that MAT1A:MAT2A expression ratio is a putative prognostic marker for human HCC.

Correlation and prognostic value of osteopontin and Bcl-2 in hepatocellular carcinoma patients after curative resection

Osteopontin (OPN) may facilitate tumorigenesis and metastasis through prevention of tumor cells from apoptosis. Although previous studies have suggested involvement of enhanced Bcl-2 protein family expression, the role of OPN together with Bcl-2 in hepatocellular carcinoma (HCC) remains unknown. In this study, we used western blotting to detect the OPN and Bcl-2 expression levels in cell lines with different OPN backgrounds and HCC tissues, and tumor tissue microarrays to examine OPN and Bcl-2 expression levels in 454 HCC cases. The Kaplan-Meier method and log-rank test were applied to investigate the predictive values of OPN and Bcl-2 in HCC patients. In vitro assays indicated that OPN expression increased concordantly with increasing metastatic potential in MHCC97-H, MHCC97-L, HepG2 and SMMC-7721 cell lines by western blotting, whereas Bcl-2 expression declined. In addition, Bcl-2 was highly upregulated in OPN knockdown MHCC97-H cell lines. Furthermore, in HCC tissues, it was confirmed that OPN levels were also significantly higher in recurrent tumor tissues compared to non-recurrent tissues by western blotting (p<0.001), whereas the contrary occurred in Bcl-2 (p=0.046). Using immunohistochemistry analysis, patients with higher OPN levels had significantly shorter median survival time and recurrence time compared to the lower ones, although the opposite occurred in Bcl-2 levels. Of note, when OPN and Bcl-2 were combined, we found that the co-index of OPN/Bcl-2 was an independent prognostic factor for both overall survival (p<0.001) and time to recurrence (p<0.001). Our findings demonstrate that OPN/Bcl-2 expression is a promising independent predictor of recurrence and survival in HCC. Additionally, Bcl-2 levels may be regulated by OPN in the HCC microenvironment.

Interactions among bone, liver, and adipose tissue predisposing to diabesity and fatty liver

Growing epidemiological evidence connects obesity and its complications, including metabolic syndrome, diabetes, and nonalcoholic fatty liver disease (NAFLD) to reduced bone health and osteoporosis. Parallel to human studies, experimental data disclosed a complex network of interaction among adipose tissue, the liver, and the bone, which reciprocally modulate the function of each other. The main mediators of such crosstalk include hormonal/cytokine signals from the bone (osteopontin, osteocalcin, and osteoprotegerin), the liver (fetuin-A), and adipose tissue [leptin, tumor necrosis factor-α (TNF-α), and adiponectin]. Dysregulation of this network promotes the development of diabesity, NAFLD, and osteoporosis. We will review recent advances in understanding the mechanisms of bone-liver-adipose tissue interaction predisposing to obesity, diabetes, NAFLD, and osteoporosis and their potential clinical implications.

Advances in understanding relationship between osteopontin and metastasis and recurrence of hepatocellular carcinoma

Osteopontin (OPN), first found in normal human tissue, is a secreted phosphorylated glycoprotein and one of the most important adhesion factors. Increased expression of OPN has been found in many types of tumors. OPN plays a very important role in the metastasis and recurrence of hepatocellular carcinoma (HCC). As a tumor marker, OPN may also become a new therapeutic target for cancer. This review aims to elucidate the structure and function of OPN, its role in HCC recurrence and metastasis, and the significance of OPN in HCC diagnosis and treatment.

SNPs in the promoter region of the osteopontin gene as a possible host factor for sex difference in hepatocellular carcinoma development in patients with HCV

AIMS

Four single nucleotide polymorphisms (SNPs) exist in the promoter region of the osteopontin (OPN) gene, namely, the SNPs at nucleotide (nt) -155, -616, and -1748 showing linkage disequilibrium to each other, and an independent SNP at nt -443. The significance of these SNPs in the risk of hepatocellular carcinoma (HCC) development was examined in patients with hepatitis C virus (HCV).

METHODS

The SNPs at nt -155 and nt -443 were analyzed in 120 patients with HCC. The promoter activity was measured in HepG2 cells by the dual-luciferase reporter assay. The electrophoretic mobility shift assay was performed using nuclear extracts from the cells.

RESULTS

Peripheral platelet counts at the time of HCC detection were greater in women with homozygous deletion at nt -155 and C/C or C/T at nt -443 than in those showing other allelic combinations, while no such difference was observed in men. The promoter activity was greater in oligonucleotides with deletions at nt -155 and C at nt -443 than in those with other haplotypes. The mobility shift assay showed double and single complexes with oligonucleotides around nt -155 and nt -443, respectively. Binding activities were greater in deletion than in G in the case of the retarded complex in the former assay and in T than in C in the latter assay. The other complex in the former assay included SRY, showing an equivalent binding activity to oligonucleotides with both alleles.

CONCLUSION

OPN promoter SNPs may play a role in the sexual difference in the risk of HCC development through the regulation of OPN expression in patients with HCV.

Myeloid differentiation factor 88 promotes growth and metastasis of human hepatocellular carcinoma

PURPOSE

To investigate the expression of myeloid differentiation factor 88 (MyD88) in hepatocellular carcinoma (HCC) and its prognostic value in patients with HCC.

EXPERIMENTAL DESIGN

Expression of MyD88 was detected by immunohistochemistry in surgical HCC specimens (n = 110). The correlation of MyD88 expression to clinicopathologic characteristics was analyzed. The involvement of MyD88 in tumor growth and invasion was investigated.

RESULTS

The expression of MyD88 was significantly higher in HCC tumors than that in adjacent nontumor tissues. Particularly, high expression of MyD88 was found in HCCs with late tumor stage (P = 0.029). Patients with high MyD88 staining revealed a higher recurrence rate (65% vs. 40%; P = 0.008). Kaplan-Meier analysis showed that recurrence-free survival (RFS; P = 0.011) and overall survival (OS; P = 0.022) were significantly worse among patients with high MyD88 staining. Univariate and multivariate analyses revealed that MyD88 was an independent predictor for OS and RFS. Ectopic expression of MyD88 promoted HCC cell proliferation and invasion in vitro. Suppression of MyD88 expression with lentivirus encoding short hairpin RNA reduced tumor growth and invasion, as well as lung metastasis. Finally, silencing of MyD88 inhibited the activation of NF-κB and AKT in HCC cells, whereas forced expression of MyD88 was able to enhance the activation of NF-κB and p38/extracellular signal-regulated kinase without Toll-like receptor/interleukin-1 receptor (TLR/IL-1R) signaling.

CONCLUSION

Elevated expression of MyD88 may promote tumor growth and metastasis via both TLR/IL-1R-dependent and -independent signaling and may serve as a biomarker for prognosis of patients with HCC.

Deregulation of signalling pathways in prognostic subtypes of hepatocellular carcinoma: novel insights from interspecies comparison

Hepatocellular carcinoma is a frequent and fatal disease. Recent researches on rodent models and human hepatocarcinogenesis contributed to unravel the molecular mechanisms of hepatocellular carcinoma dedifferentiation and progression, and allowed the discovery of several alterations underlying the deregulation of cell cycle and signalling pathways. This review provides an interpretive analysis of the results of these studies. Mounting evidence emphasises the role of up-regulation of RAS/ERK, P13K/AKT, IKK/NF-kB, WNT, TGF-ß, NOTCH, Hedgehog, and Hippo signalling pathways as well as of aberrant proteasomal activity in hepatocarcinogenesis. Signalling deregulation often occurs in preneoplastic stages of rodent and human hepatocarcinogenesis and progressively increases in carcinomas, being most pronounced in more aggressive tumours. Numerous changes in signalling cascades are involved in the deregulation of carbohydrate, lipid, and methionine metabolism, which play a role in the maintenance of the transformed phenotype. Recent studies on the role of microRNAs in signalling deregulation, and on the interplay between signalling pathways led to crucial achievements in the knowledge of the network of signalling cascades, essential for the development of adjuvant therapies of liver cancer. Furthermore, the analysis of the mechanisms involved in signalling deregulation allowed the identification of numerous putative prognostic markers and novel therapeutic targets of specific hepatocellular carcinoma subtypes associated with different biologic and clinical features. This is of prime importance for the selection of patient subgroups that are most likely to obtain clinical benefit and, hence, for successful development of targeted therapies for liver cancer.

Proteins involved in regulating bone invasion in skull base meningiomas

Background

Bone invasive skull base meningiomas are a subset of meningiomas that present a unique clinical challenge due to brain and neural structure involvement and limitations in complete surgical resection, resulting in higher recurrence and need for repeat surgery. To date, the pathogenesis of meningioma bone invasion has not been investigated. We investigated immunoexpression of proteins implicated in bone invasion in other tumor types to establish their involvement in meningioma bone invasion.

Methods

Retrospective review of our database identified bone invasive meningiomas operated on at our institution over the past 20 years. Using high-throughput tissue microarray (TMA), we established the expression profile of osteopontin (OPN), matrix metalloproteinase-2 (MMP2), and integrin beta-1 (ITGB1). Differential expression in tumor cell and vasculature was evaluated and comparisons were made between meningioma anatomical locations.

Results

MMP2, OPN, and ITGB1 immunoreactivity was cytoplasmic in tumor and/or endothelial cells. Noninvasive transbasal meningiomas exhibited higher vascular endothelial cell MMP2 immunoexpression compared to invasive meningiomas. We found higher expression levels of OPN and ITGB1 in bone invasive transbasal compared to noninvasive meningiomas. Strong vascular ITGB1 expression extending from the endothelium through the media and into the adventitia was found in a subset of meningiomas.

Conclusions

We have demonstrated that key proteins are differentially expressed in bone invasive meningiomas and that the anatomical location of bone invasion is a key determinant of expression pattern of MMP1, OPN, and ITGB1. This data provides initial insights into the pathophysiology of bone invasion in meningiomas and identifies factors that can be pursued as potential therapeutic targets.

Osteopontin promoter polymorphisms at locus -443 significantly affect the metastasis and prognosis of human hepatocellular carcinoma

Osteopontin (OPN) plays a crucial role in hepatocellular carcinoma (HCC) metastasis. However, little is known about the impact of OPN polymorphisms on cancer progression. In this study, we first identified the single nucleotide polymorphisms (SNPs) in the OPN promoter region by direct sequencing in 30 HCCs, and then evaluated the prognostic values of the selected ones in two large cohorts of 826 HCC patients. The identified SNPs were functionally analyzed using in vitro and in vivo assays and their correlations with OPN levels were also evaluated. Only SNP at locus -443 and their related haplotypes (Ht2: -1748A/-616G/-443T/-155* [*indicates base deletion]; Ht3: -1748A/-616G/-443C/-155*) were significantly associated with overall survival (OS) and time to recurrence (TTR). The patients with the -443TT/TC genotype or Ht2 had a shorter OS and TTR compared with those with -443CC genotype or Ht3. This was further confirmed in the validation cohort. Moreover, this correlation remained significant in patients with small HCCs (≤5 cm). Multivariate analyses indicated that the prognostic performance of the -443 genotypes (OS, P=0.031; TTR, P=0.005) and their related haplotypes (OS, P=0.002; TTR, P=0.001) was independent of other clinicopathological factors. The Ht2 and -443TT genotype could significantly increase the promoter transcriptional activity and expression level of OPN compared with the Ht3 or -443CC genotype, and lead to an obvious increase in both in vitro invasion and in vivo tumor growth and lung metastasis of HCC cells (P<0.05).

CONCLUSION

The genetic variation at locus -443 of the OPN promoter plays important roles in the regulation of OPN expression and cancer progression of HCCs, which is a novel determinant and target for HCC metastasis and prognosis.

Aerosol delivery of lentivirus-mediated O-glycosylation mutant osteopontin suppresses lung tumorigenesis in K-ras (LA1) mice

BACKGROUND

Osteopontin (OPN) is a secreted glycophosphoprotein that has been implicated in the regulation of cancer development. The function of OPN is primarily regulated through post-translational modification such as glycosylation. As yet, however, the relationship between OPN glycosylation and lung cancer development has not been investigated. In this study, we addressed this issue by studying the effect of a triple mutant (TM) of OPN, which is mutated at three O-glycosylation sites, on lung cancer development in K-ras (LA1) mice, a murine model for human non-small cell lung cancer.

METHODS

Aerosolized lentivirus-based OPN TM was delivered into the lungs of K-ras (LA1) mice using a nose-only-inhalation chamber 3 times/wk for 4 wks. Subsequently, the effects of repeated delivery of OPN TM on lung tumorigenesis and its concomitant OPN-mediated signaling pathways were investigated.

RESULTS

Aerosol-delivered OPN TM inhibited lung tumorigenesis. In addition, the OPN-mediated Akt signaling pathway was inhibited. OPN TM also decreased NF-κB activity and the phosphorylation of 4E-BP1, while facilitating apoptosis in the lungs of K-ras (LA1) mice.

CONCLUSIONS

Our results show that aerosol delivery of OPN TM successfully suppresses lung cancer development in the K-ras (LA1) mouse model and, therefore, warrant its further investigation as a possible therapeutic strategy for non-small cell lung cancer.

Breast cancer metastasis suppressor 1 regulates hepatocellular carcinoma cell apoptosis via suppressing osteopontin expression

Breast cancer metastasis suppressor 1 (BRMS1) was originally identified as an active metastasis suppressor in human breast cancer. Loss of BRMS1 expression correlates with tumor progression, and BRMS1 suppresses several steps required for tumor metastasis. However, the role of BRMS1 in hepatocellular carcinoma (HCC) remains elusive. In this study, we found that the expression level of BRMS1 was significantly down-regulated in HCC tissues. Expression of BRMS1 in SK-Hep1 cells did not affect cell growth under normal culture conditions, but sensitized cells to apoptosis induced by serum deprivation or anoikis. Consistently, knockdown of endogenous BRMS1 expression in Hep3B cells suppressed cell apoptosis. We identified that BRMS1 suppresses osteopontin (OPN) expression in HCC cells and that there is a negative correlation between BRMS1 and OPN mRNA expression in HCC tissues. Moreover, knockdown of endogenous OPN expression reversed the anti-apoptosis effect achieved by knockdown of BRMS1. Taken together, our results show that BRMS1 sensitizes HCC cells to apoptosis through suppressing OPN expression, suggesting a potential role of BRMS1 in regulating HCC apoptosis and metastasis.

Osteopontin as potential biomarker and therapeutic target in gastric and liver cancers

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 increases hepatocellular carcinoma cell growth in a CD44 dependant manner

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.

Functional genomic studies: insights into the pathogenesis of liver cancer

Liver cancer is the sixth-most-common cancer overall but the third-most-frequent cause of cancer death. Among primary liver cancers, hepatocellular carcinoma (HCC), the major histological subtype, is associated with multiple risk factors, including hepatitis B and C virus infection, alcohol consumption, obesity, and diet contamination. Although previous studies have revealed that certain genetic and epigenetic changes, such as TP53 and β-catenin mutations, occur in HCC cells, the pathogenesis of this cancer remains obscure. Functional genomic approaches-including genome-wide association studies, whole-genome and whole-exome sequencing, array-based comparative genomic hybridization, global DNA methylome mapping, and gene or noncoding RNA expression profiling-have recently been applied to HCC patients with different clinical features to uncover the genetic risk factors and underlying molecular mechanisms involved in this cancer's initiation and progression. The genome-wide analysis of germline and somatic genetic and epigenetic events facilitates understanding of the pathogenesis and molecular classification of liver cancer as well as the identification of novel diagnostic biomarkers and therapeutic targets for cancer.

Growth inhibition and apoptosis induced by osthole, a natural coumarin, in hepatocellular carcinoma

Background

Hepatocellular carcinoma (HCC) is one of the most commonly diagnosed tumors worldwide and is known to be resistant to conventional chemotherapy. New therapeutic strategies are urgently needed for treating HCC. Osthole, a natural coumarin derivative, has been shown to have anti-tumor activity. However, the effects of osthole on HCC have not yet been reported.

Methods and Findings

HCC cell lines were treated with osthole at various concentrations for 24, 48 and 72 hours. The proliferations of the HCC cells were measured by MTT assays. Cell cycle distribution and apoptosis were determined by flow cytometry. HCC tumor models were established in mice by subcutaneously injection of SMMC-7721 or Hepa1-6 cells and the effect of osthole on tumor growths in vivo and the drug toxicity were studied. NF-κB activity after osthole treatment was determined by electrophoretic mobility shift assays and the expression of caspase-3 was measured by western blotting. The expression levels of other apoptosis-related genes were also determined by real-time PCR (PCR array) assays. Osthole displayed a dose- and time-dependent inhibition of the HCC cell proliferations in vitro. It also induced apoptosis and caused cell accumulation in G2 phase. Osthole could significantly suppress HCC tumor growth in vivo with no toxicity at the dose we used. NF-κB activity was significantly suppressed by osthole at the dose- and time-dependent manner. The cleaved caspase-3 was also increased by osthole treatment. The expression levels of some apoptosis-related genes that belong to TNF ligand family, TNF receptor family, Bcl-2 family, caspase family, TRAF family, death domain family, CIDE domain and death effector domain family and CARD family were all increased with osthole treatment.

Conclusion

Osthole could significantly inhibit HCC growth in vitro and in vivo through cell cycle arrest and inducing apoptosis by suppressing NF-κB activity and promoting the expressions of apoptosis-related genes.

Osteopontin is involved in estrogen-mediated protection against diethylnitrosamine-induced liver injury in mice

Diethylnitrosamine (DEN) is a potent hepatotoxin and hepatocarcinogen in animals and possible in humans. Estrogen has been reported to play a protective role against DEN exposure. Osteopontin (OPN), a downstream molecular of estrogen, plays a role in many pathophysiological processes. In this study, we evaluate the role of OPN in estrogen-mediated hepatoprotection in DEN-treated mice. DEN was administrated intraperitoneally to C57BL/6 and OPN(-/-) mice. Compared to male mice, female mice exhibited significantly higher hepatic OPN expression with less liver damage 48 h after DEN treatment. Interestingly, enhanced OPN expression was predominantly detected in hepatocytes after DEN treatment. OPN deficiency enhanced the susceptibility to DEN, which was more apparent in females than males. Estrogen-mediated protection against DEN in males was abrogated by OPN deficiency. The protective activities of estrogen could be mimicked by exogenous OPN. Consistent with liver injury, oxidative stress in liver was enhanced with OPN depletion. OPN reduced DEN-induced oxidative stress likely through inhibition of CYP2A5 expression. In conclusion, we demonstrate that OPN may be involved in estrogen-mediated hepatoprotection in DEN-induced liver injury through enhancement of hepatocyte survival and inhibition of DEN biotransformation. Our findings may provide new insight into gender differences in chemical-induced liver injury and related diseases.

The osteopontin level in liver, adipose tissue and serum is correlated with fibrosis in patients with alcoholic liver disease

Background

Osteopontin (OPN) plays an important role in the progression of chronic liver diseases. We aimed to quantify the liver, adipose tissue and serum levels of OPN in heavy alcohol drinkers and to compare them with the histological severity of hepatic inflammation and fibrosis.

Methodology/Principal Findings

OPN was evaluated in the serum of a retrospective and prospective group of 109 and 95 heavy alcohol drinkers, respectively, in the liver of 34 patients from the retrospective group, and in the liver and adipose tissue from an additional group of 38 heavy alcohol drinkers. Serum levels of OPN increased slightly with hepatic inflammation and progressively with the severity of hepatic fibrosis. Hepatic OPN expression correlated with hepatic inflammation, fibrosis, TGFβ expression, neutrophils accumulation and with the serum OPN level. Interestingly, adipose tissue OPN expression also correlated with hepatic fibrosis even after 7 days of alcohol abstinence. The elevated serum OPN level was an independent risk factor in estimating significant (F≥2) fibrosis in a model combining alkaline phosphatase, albumin, hemoglobin, OPN and FibroMeter® levels. OPN had an area under the receiving operator curve that estimated significant fibrosis of 0.89 and 0.88 in the retrospective and prospective groups, respectively. OPN, Hyaluronate (AUROC: 0.88), total Cytokeratin 18 (AUROC: 0.83) and FibroMeter® (AUROC: 0.90) estimated significance to the same extent in the retrospective group. Finally, the serum OPN levels also correlated with hepatic fibrosis and estimated significant (F≥2) fibrosis in 86 patients with chronic hepatitis C, which suggested that its elevated level could be a general response to chronic liver injury.

Conclusion/Significance

OPN increased in the liver, adipose tissue and serum with liver fibrosis in alcoholic patients. Further, OPN is a new relevant biomarker for significant liver fibrosis. OPN could thus be an important actor in the pathogenesis of this chronic liver disease.

Osteopontin regulates epithelial mesenchymal transition-associated growth of hepatocellular cancer in a mouse xenograft model

OBJECTIVE

To determine the efficacy of osteopontin (OPN) targeting in hepatocellular cancer (HCC). SUMMARY/BACKGROUND: OPN is associated with HCC growth and metastasis and represents a unique therapeutic target.

METHODS

OPN and epithelial-mesenchymal transition (EMT) markers, α-smooth muscle actin (SMA), vimentin, and tenascin-c, were measured in archived human HCC tissues from metastatic (n = 4) and nonmetastatic (n = 4) settings. Additional studies utilized human Sk-Hep-1 (high OPN expression) and Hep3b (low OPN expression) HCC cells. An RNA aptamer (APT) that avidly binds (Kd = 18 nM; t1/2 = 7 hours) and ablates OPN binding was developed. Adhesion, migration/invasion, and EMT markers were determined with APT or a mutant control aptamer (Mu-APT). RFP-Luc-Sk-Hep-1 were implanted into NOD-scid mice livers and followed by using bioluminescence imaging. After verification of tumor growth, at week 3, APT (0.5 mg/kg; n = 4) or Mu-APT (0.5 mg/kg; n = 4) was injected q48h. When mice were killed at week 8, tumor cells were reisolated and assayed for EMT markers.

RESULTS

OPN and EMT markers were significantly increased in the metastatic cohort. APT inhibited Sk-Hep-1 adhesion and migration/invasion by 5- and 4-fold, respectively. APT significantly decreased EMT protein markers, SMA, vimentin, and tenascin-c. In contrast, APT did not alter Hep3B adhesion, or migration/invasion. EMT markers were slightly decreased. In the in vivo model, at weeks 6 to 8, APT inhibited HCC growth by more than 10-fold. SMA, vimentin, and tenascin-c mRNAs were decreased by 60%, 40%, and 49%, respectively, in RFP-positive Sk-Hep-1 recovered by fluorescence-activated cell sorting (P < 0.04 vs Mu-APT for all).

CONCLUSIONS

APT targeting of OPN significantly decreases EMT and tumor growth of HCC.

Identification of osteopontin as a novel marker for early hepatocellular carcinoma

The aim of this study was to identify a biomarker that could improve alpha-fetoprotein (AFP) performance in hepatocellular carcinoma (HCC) surveillance among patients with cirrhosis. We performed proteomic profiling of plasma from patients with cirrhosis or HCC and validated selected candidate HCC biomarkers in two geographically distinct cohorts to include HCC of different etiologies. Mass spectrometry profiling of highly fractionated plasma from 18 cirrhosis and 17 HCC patients identified osteopontin (OPN) as significantly up-regulated in HCC cases, compared to cirrhosis controls. OPN levels were subsequently measured in 312 plasma samples collected from 131 HCC patients, 76 cirrhosis patients, 52 chronic hepatitis C (CHC) and B (CHB) patients, and 53 healthy controls in two independent cohorts. OPN plasma levels were significantly elevated in HCC patients, compared to cirrhosis, CHC, CHB, or healthy controls, in both cohorts. OPN alone or in combination with AFP had significantly better area under the receiver operating characteristic curve, compared to AFP, in comparing cirrhosis and HCC in both cohorts. OPN overall performance remained higher than AFP in comparing cirrhosis and the following HCC groups: HCV-related HCC, HBV-associated HCC, and early HCC. OPN also had a good sensitivity in AFP-negative HCC. In a pilot prospective study including 22 patients who developed HCC during follow-up, OPN was already elevated 1 year before diagnosis.

CONCLUSION

OPN was more sensitive than AFP for the diagnosis of HCC in all studied HCC groups. In addition, OPN performance remained intact in samples collected 1 year before diagnosis.

Dual-modality monitoring of tumor response to cyclophosphamide therapy in mice with bioluminescence imaging and small-animal positron emission tomography

The purpose of this study was to noninvasively monitor the therapeutic efficacy of cyclophosphamide (CTX) in a mouse model by dual-modality molecular imaging: positron emission tomography (PET) and bioluminescence imaging (BLI). Firefly luciferase (fLuc) transfected HCC-LM3-fLuc human hepatocellular carcinoma cells were injected subcutaneously into BALB/c nude mice to establish the experimental tumor model. Two groups of HCC-LM3-fLuc tumor-bearing mice (n  =  7 per group) were treated with saline or CTX (100 mg/kg on days 0, 2, 5, and 7). BLI and (18)F-fluorodeoxyglucose ((18)F-FDG) PET scans were done to evaluate the treatment efficacy. CTX induced a 25.25 ± 13.13% and 35.91 ± 25.85% tumor growth inhibition rate on days 9 and 12 posttreatment, respectively, as determined by BLI. A good linear correlation was found between the tumor sizes measured by caliper and the BLI signals determined by optical imaging (R(2)  =  .9216). (18)F-FDG imaging revealed a significant uptake reduction in the tumors of the CTX-treated group compared to that in the saline control group (5.30 ± 1.97 vs 3.00 ± 2.11% ID/g) on day 16 after CTX treatment. Dual-modality molecular imaging using BLI and small-animal PET can play important roles in the process of chemotherapy and will provide noninvasive and reliable monitoring of the therapeutic response.

Early detection of liver cancer based on bioluminescence tomography

As a new modality of molecular imaging, bioluminescence imaging has been widely used in tumor detection and drug evaluation. However, BLI cannot present the depth of information for internal diseases such as a liver tumor in situ or a lung tumor in situ. In this paper, we describe a bioluminescence tomography (BLT) method based on the bioluminescent intensity attenuation calibration and applied it to the early detection of liver cancer in situ. In comparison with BLT without calibration, this method could improve the reconstruction accuracy by more than 10%. In comparison with micro-computed tomography and other traditional imaging modalities, this method can detect a liver tumor at a very early stage and provide reliable location information.

Butyrate suppresses mRNA increase of osteopontin and cyclooxygenase-2 in human colon tumor tissue

The short chain fatty acid (SCFA) butyrate, a product of fermentation of dietary fiber in the human colon, is found to exert multiple regulatory processes in colon carcinogenesis. The aim of this study was to find out whether butyrate affects the tumor-promoting genes osteopontin (OPN) and cyclooxygenase (COX)-2, their respective proteins and/or their functional activity in matched normal, adenoma and tumor colon tissues obtained from 20 individuals at colon cancer surgery. Quantitative real-time polymerase chain reaction experiments showed increased levels of OPN and COX-2 messenger RNA in tumor tissues when compared with the adjacent normal samples (P < 0.001). The addition of butyrate reduced OPN and COX-2 mRNA expression in all tissue types compared with the related medium controls (tumor: P < 0.05). In tumor samples, a downregulation of up to median 35% (COX-2) and 50% (OPN) was observed, respectively. Thereby, tumors with lower levels of OPN basal expression were more sensitive to inhibition and vice versa for COX-2 in normal tissue. At the protein and enzyme level, which were determined by using western blot and enzyme immunometric assays, the impact of the SCFA was not clearly visible anymore. The active proteins of OPN and COX-2 (determined by prostaglandin E(2)) were found to correlate with their respective mRNA expression only in 50-63% of analyzed donors. For the first time, our data reveal new insights into the chemoprotective potential of butyrate by showing the suppression of OPN and COX-2 mRNA in primary human colon tissue with the strongest effects observed in tumors.

Role of methionine adenosyltransferase genes in hepatocarcinogenesis

Hepatocellular carcinoma (HCC) is the most common primary malignant tumor of the liver. Detection of HCC can be difficult, as most of the patients who develop this tumor have no symptoms other than those related to their longstanding liver disease. There is an urgent need to understand the molecular mechanisms that are responsible for the development of this disease so that appropriate therapies can be designed. Methionine adenosyltransferase (MAT) is an essential enzyme required for the biosynthesis of S-adenosylmethionine (AdoMet), an important methyl donor in the cell. Alterations in the expression of MAT genes and a decline in AdoMet biosynthesis are known to be associated with liver injury, cirrhosis and HCC. This review focuses on the role of MAT genes in HCC development and the scope for therapeutic strategies using these genes.

Osteopontin expression predicts overall survival after liver transplantation for hepatocellular carcinoma in patients beyond the Milan criteria

BACKGROUND & AIMS

Microarray data showed that osteopontin overexpression predicts early HCC-recurrence after liver resection. Osteopontin (OPN) expression could serve as a predictor of HCC-recurrence after OLT.

METHODS

Osteopontin expression was investigated immunohistochemically in a unique population of 125 HCC-patients undergoing OLT between 1982 and 2002, including 81 patients (65%) outside the Milan criteria. Multivariate analysis of factors associated with median overall survival (OS) and time to recurrence (TTR) was performed.

RESULTS

Osteopontin was expressed in 40/125 (32%) of the HCCs. Overall survival post-OLT at 1, 2, 3, 5 years was 77%, 62%, 52%, and 43% (median survival 37 months). Overall survival was significantly longer without expression of OPN (p < 0.05; (median OS: 56 vs. 23 months). The same was true for median TTR (p = 0.008). Outside Milan criteria, patients without OPN-expression had better prognosis (median OS: 37.8 vs. 19.2 months, p = 0.003). Tumor recurrence in patients transplanted outside Milan criteria occurred in 43% (23 of 54) of patients without and 70% (19 of 27, p = 0.018) of patients with OPN-expression after a median TTR of 83.5 vs. 13.9 months. On multivariate analysis, vascular invasion and OPN-expression were independently associated with OS and TTR in HCC-patients after OLT.

CONCLUSIONS

Immunohistochemically detectable Osteopontin in HCC is an independent predictor of tumor recurrence and survival in patients beyond Milan criteria undergoing OLT.

Osteopontin expression correlates with nuclear factor-κB activation and apoptosis downregulation in clear cell renal cell carcinoma

Osteopontin (OPN) is a phosphoglycoprotein implicated in tumorigenesis and tumor cell metastasis. Apoptosis inhibition is one of the mechanisms that contribute to development and progression of cancer, and might be initiated by OPN interaction with tumor cells. The aim of this study was to analyze the relation between OPN and nuclear factor-kappa B (NF-κB) expression in clear cell renal cell carcinoma (CCRCC), as well as their relation to apoptotic activity of tumor cells. Expression of OPN protein and p65 NF-κB subunit was analyzed immunohistochemically in 87 CCRCC samples, and compared mutually and with apoptotic index. Expression of OPN mRNA was analyzed using quantitative real-time PCR and compared with OPN and NF-κB protein expression in 22 CCRCC samples. Statistical analysis showed an association of p65 NF-κB with OPN mRNA (p=0.015) and protein (p<0.001). Also, we found an inverse relationship of OPN with NF-κB protein expression and apoptotic activity of tumor cells (p=0.006 and p=0.022, respectively). Our results indicate that p65 NF-κB signaling pathway may be involved in OPN-mediated CCRCC progression, partly by protecting tumor cells from apoptosis. Therefore, both molecules can constitute potential targets for therapeutic intervention in CCRCC.

Fibroblast and prostate tumor cell cross-talk: fibroblast differentiation, TGF-β, and extracellular matrix down-regulation

Growth and survival of tumors at a site of metastasis involve interactions with stromal cells in the surrounding environment. Stromal cells aid tumor cell growth by producing cytokines as well as by modifying the environment surrounding the tumor through modulation of the extracellular matrix (ECM). Small leucine-rich proteoglycans (SLRPs) are biologically active components of the ECM which can be altered in the stroma surrounding tumors. The influence tumor cells have on stromal cells has been well elucidated. However, little is understood about the effect metastatic cancer cells have on the cell biology and behavior of the local stromal cells. Our data reveal a significant down-regulation in the expression of ECM components such as collagens I, II, III, and IV, and the SLRPs, decorin, biglycan, lumican, and fibromodulin in stromal cells when grown in the presence of two metastatic prostate cancer cell lines PC3 and DU145. Interestingly, TGF-β down-regulation was observed in stromal cells, as well as actin depolymerization and increased vimentin and α5β1 integrin expression. MT1-MMP expression was upregulated and localized in stromal cell protrusions which extended into the ECM. Moreover, enhanced stromal cell migration was observed after cross-talk with metastatic prostate tumor cells. Xenografting metastatic prostate cancer cells together with "activated" stromal cells led to increased tumorigenicity of the prostate cancer cells. Our findings suggest that metastatic prostate cancer cells create a metastatic niche by altering the phenotype of local stromal cells, leading to changes in the ECM.

Osteopontin is up-regulated and associated with neutrophil and macrophage infiltration in glioblastoma

Osteopontin (OPN) is a glycophosphoprotein with multiple intracellular and extracellular functions. In vitro, OPN enhances migration of mouse neutrophils and macrophages. In cancer, extracellular OPN facilitates migration of cancer cells via its RGD sequence. The present study was designed to investigate whether osteopontin is responsible for neutrophil and macrophage infiltration in human cancer and in particular in glioblastoma. We found that in vitro mouse neutrophil migration was RGD-dependent. In silico, we found that the OPN gene was one of the 5% most highly expressed genes in 20 out of 35 cancer microarray data sets in comparison with normal tissue in at least 30% of cancer patients. In some types of cancer, such as ovarian cancer, lung cancer and melanoma, the OPN gene was one of those with the highest expression levels in at least 90% of cancer patients. In glioblastoma, the most invasive type of brain tumours/glioma, but not in lower grades of glioma it was one of the 5% highest expressed genes in 90% of patients. In situ, we found increased protein levels of OPN in human glioblastoma versus normal human brain confirming in silico results. OPN protein expression was co-localized with neutrophils and macrophages. In conclusion, OPN in tumours not only induces migration of cancer cells but also of leucocytes.

Osteopontin is a new target molecule for ovarian clear cell carcinoma therapy

Recent studies have demonstrated overexpression of osteopontin (OPN) in ovarian clear cell carcinoma. Here, we revealed the role of OPN in invasiveness in ovarian clear cell carcinoma. We used immunofluorescence analysis to detect OPN in a total of 160 patient-derived specimens. Ovarian clear cell carcinoma cell lines, RMG-1 and TOV-21G, were used to monitor changes in OPN and integrin levels, and cell invasiveness following treatment with OPN, simvastatin, and transfection with siRNA. Immunofluorescence analysis revealed statistically significant differences among the histological groups, and ovarian clear cell carcinoma expressed a strong OPN signal. The OPN receptors, alpha v and 5, and beta 1 and 3 integrins, were increased after treatment with OPN. Invasion assays indicated that OPN enhanced in vitro extracellular matrix invasion dose-dependently in ovarian clear cell carcinoma. Simvastatin significantly reduced expression of OPN and the integrins, and decreased ECM invasion. RNA interference also suppressed ECM invasion. These results suggest that down- or up-regulation of OPN is involved in carcinoma cell invasion. We thus conclude that OPN regulation could have a crucial role in ovarian clear cell carcinoma therapy.

Workflow comparison for label-free, quantitative secretome proteomics for cancer biomarker discovery: method evaluation, differential analysis, and verification in serum

The cancer cell secretome has emerged as an attractive subproteome for discovery of candidate blood-based biomarkers. To choose the best performing workflow, we assessed the performance of three first-dimension separation strategies prior to nanoLC-MS/MS analysis: (1) 1D gel electrophoresis (1DGE), (2) peptide SCX chromatography, and (3) tC2 protein reversed phase chromatography. 1DGE using 4-12% gradient gels outperformed the SCX and tC2 methods with respect to number of identified proteins (1092 vs 979 and 580, respectively), reproducibility of protein identification (80% vs 70% and 72%, respectively, assessed in biological N = 3). Reproducibility of protein quantitation based on spectral counting was similar for all 3 methods (CV: 26% vs 24% and 24%, respectively). As a proof-of-concept of secretome proteomics for blood-based biomarker discovery, the gradient 1DGE workflow was subsequently applied to identify IGF1R-signaling related proteins in the secretome of mouse embryonic fibroblasts transformed with human IGF1R (MEF/Toff/IGF1R). VEGF and osteopontin were differentially detected by LC-MS/MS and verified in secretomes by ELISA. Follow-up in serum of mice bearing MEF/Toff/IGF1R-induced tumors showed an increase of osteopontin levels paralleling tumor growth, and reduction in the serum of mice in which IGF1R expression was shut off and tumor regressed.

Osteopontin expression is an independent adverse prognostic factor in resectable gastrointestinal stromal tumor and its interaction with CD44 promotes tumor proliferation

BACKGROUND

Osteopontin (OPN) is a multifunctional secreted glycophosphoprotein involved in miscellaneous physiologic and pathologic processes and is functionally related to the transmembrane receptor CD44. Although OPN expression has been identified to be associated with poor prognosis in several gastrointestinal malignancies, its expression in gastrointestinal stromal tumor (GIST) has not been thoroughly investigated. This study was designed to evaluate the clinicopathologic significance of OPN expression in patients with resectable GIST.

METHODS

OPN expression was analyzed for its clinicopathologic significance in surgical specimens from 99 patients with resectable GIST by immunohistochemistry. In situ Proximity Ligation Assay was used for examining OPN and CD44 interaction in tumor tissues and GIST cell lines. The in vitro effects of OPN and its interaction with CD44 also were assessed.

RESULTS

Increased OPN expression was a significant poor prognostic factor that independently predicted recurrence and poor disease-free survival in patients with resectable GIST. The interaction of OPN and CD44 was confirmed by their significant correlation in both GIST tumor tissues and cell lines by in situ Proximity Ligation Assay analysis. OPN and its interaction with CD44 were related to increased mitosis and significantly enhanced GIST tumor cell proliferation in vitro.

CONCLUSIONS

Our study identified the clinicopathologic significance and biologic effects of OPN expression in resectable GIST. Increased OPN expression was an independent poor prognostic factor and its interaction with CD44 significantly correlated with increased mitosis as well as in vitro proliferation-promoting effects.

Osteopontin: an effector and an effect of tumor metastasis

Osteopontin (OPN) is a matricellular protein that is produced by multiple tissues in our body and is most abundant in bone. It is also produced by cancer cells and plays a determinative role in the growth, progression and metastasis of cancer. Clinically, OPN has been reported to be upregulated in tumor cells per se; this is also reflected by increased levels of OPN in the circulation. Thus, increased OPN levels the plasma are an effect of tumor growth and progression. Functionally, high OPN levels are determinative of higher incidence of bone metastases in mouse models and are clinically correlated with metastatic bone disease and bone resorption in advanced breast cancer patients. Several research efforts have been made to therapeutically target and inhibit the activities of OPN. In this article we have reviewed OPN in its role as an effector of critical steps in tumor progression and metastasis, with a particular emphasis on its role in facilitating bone metastasis of breast cancer. We have also addressed the role of the host-derived OPN in influencing the malignant behavior of the tumor cells.

Inhibitory action of Wnt target gene osteopontin on mitochondrial cytochrome c release determines renal ischemic resistance

Certain determinants of ischemic resistance in the Brown Norway rat strain have been proposed, but no studies to date have focused on the role of the Wnt pathway in the ischemic resistance mechanism. We performed a comparative genomic study in Brown Norway vs. Sprague-Dawley rats. Selective manipulations of the Wnt pathway in vivo and in vitro allowed us to study whether the action of the Wnt pathway on apoptosis through the regulation of osteopontin was critical to the maintenance of inherent ischemic resistance mechanisms. The results revealed a major gene upregulation of the Wnt family in Brown Norway rats after renal ischemia-reperfusion. Manipulation of the Wnt signaling cascade by selective antibodies increased mitochondrial cytochrome c release and caspase 3 activity. The antiapoptotic role of Wnt was mediated by osteopontin, a direct Wnt target gene. Osteopontin was reduced by Wnt antibody administration in vivo, and osteopontin gene silencing in vitro significantly increased mitochondrial cytochrome c release. The overexpression of Wnt pathway genes detected in Brown Norway rats is critical in the maintenance of their inherent ischemic resistance. Activation of the Wnt signaling cascade reduces mitochondrial cytochrome c release and caspase 3 activity through the action of osteopontin.

Forced expression of methionine adenosyltransferase 1A in human hepatoma cells suppresses in vivo tumorigenicity in mice

Methionine adenosyltransferase (MAT) catalyzes the synthesis of S-adenosylmethionine, the principal methyl donor, and is encoded by MAT1A and MAT2A in mammals. Normal liver expresses MAT1A, which is silenced in hepatocellular carcinoma. We have shown that hepatoma cells overexpressing MAT1A grew slower, but whether this is also true in vivo remains unknown. To investigate the effect of overexpressing MAT1A on in vivo tumorigenesis, we generated stable transfectants of Huh7 cells overexpressing either MAT1A or empty vector. Real-time PCR and Western blotting were used to measure expression, and BALB/c nude mice were injected subcutaneously with untransfected or Huh7 cells transfected with empty or MAT1A expression vector to establish tumors. Tumor properties such as proliferation, angiogenesis, and apoptosis were compared, and microarray analysis was performed. Huh7 cells overexpressing MAT1A had higher S-adenosylmethionine levels but lower bromodeoxyuridine incorporation than control cells. Tumor growth rates and weights were lower in MAT1A transfected tumors. In addition, microvessel density and CD31 and Ki-67 staining were lower in MAT1A transfected tumors than control tumors, whereas the apoptosis index was higher in MAT1A-transfected tumors. Forced expression of MAT1A induced genes related to apoptosis and tumor suppression and lowered expression of cell growth and angiogenesis proteins. Our data demonstrate in vivo overexpression of MAT1A in liver cancer cells can suppress tumor growth. They also suggest inducing MAT1A expression might be a strategy to treat hepatocellular carcinoma.

Inhibition of osteopontin reduces liver metastasis of human pancreatic cancer xenografts injected into the spleen in a mouse model

PURPOSE

Pancreatic cancer is associated with the poorest prognosis of any digestive cancer due to the high incidence of liver metastasis. This study evaluated the possibility that osteopontin (OPN) RNA interference (RNAi) and anti-OPN antibody (Ab) could have antimetastatic effects.

METHODS

The differential gene expression was measured in a parental cell line, HPC-3, and an established highly liver metastatic cell line, HPC-3H4. This study investigated the effect of OPN RNAi and anti-OPN Ab on the metastatic ability of HPC-3H4 to the liver. An OPN RNAi-expressing vector was introduced into HPC-3H4 cells (HPC-3H4/miOPN), in which OPN production was reduced to the level of the parental HPC-3 cells. Finally, the ability of anti-OPN Ab to suppress liver metastasis was investigated.

RESULTS

Osteopontin was upregulated 11.1-fold in HPC-3H4 in comparison to HPC-3. The metastatic rate of HPC-3H4/miOPN was significantly reduced to 25% in comparison to the 100% metastatic rate of HPC-3H4 and control HPC-3H4/miNeg cells (P < 0.01). The metastatic rate of the group given anti-OPN Ab was 50%.

CONCLUSION

OPN RNAi and anti-OPN Ab had remarkable inhibitory effects against liver metastasis by the pancreatic cancer cell line.

The RGD domain of human osteopontin promotes tumor growth and metastasis through activation of survival pathways

BACKGROUND

Human osteopontin (OPN), a known tumor associated protein, exists in different isoforms, whose function is unclear. It also possesses a RGD domain, which has been implicated in diverse function. Here, we use genetic approaches to systematically investigate the function of the RGD domain in different OPN isoforms on tumor progression and metastasis for 2 different solid tumor models.

METHODOLOGY/PRINCIPAL FINDINGS

Using isoform-specific qRT-PCR, we found that OPN-A and B were the main isoforms overexpressed in evaluated human tumors, which included 4 soft tissue sarcomas, 24 lung and 30 head and neck carcinomas. Overexpression of either OPN-A or B in two different cell types promoted local tumor growth and lung metastasis in SCID mouse xenografts. However, expression of either isoform with the RGD domain either mutated or deleted decreased tumor growth and metastasis, and resulted in increased apoptosis by TUNEL staining. In vitro, whereas mutation of the RGD domain did not affect cell-cell adhesion, soft agar growth or cell migration, it increased apoptosis under hypoxia and serum starvation. This effect could be mitigated when the RGD mutant cells were treated with condition media containing WT OPN. Mechanistically, the RGD region of OPN inhibited apoptosis by inducing NF-kappaB activation and FAK phosphorylation. Inhibition of NF-kappaB (by siRNA to the p65 subunit) or FAK activation (by a inhibitor) significantly increased apoptosis under hypoxia in WT OPN cells, but not in RGD mutant cells.

CONCLUSION/SIGNIFICANCE

Unlike prior reports, our data suggest that the RGD domain of both OPN-A and B promote tumor growth and metastasis mainly by protecting cells against apoptosis under stressed conditions and not via migration or invasion. Future inhibitors directed against OPN should target multiple isoforms and should inhibit cell survival mechanisms that involve the RGD domain, FAK phosphorylation and NF-kappaB activation.

Differential expression profiling between atypical teratoid/rhabdoid and medulloblastoma tumor in vitro and in vivo using microarray analysis

OBJECTIVES

Atypical teratoid/rhabdoid tumor (AT/RT) and medulloblastoma (MB) are the most malignant primary brain tumors in early childhood. AT/RT is frequently misdiagnosed as primitive neuroectodermal tumor/medulloblastoma. The biological features and clinical outcomes of AT/RT and MB are extremely different. In this study, we used microarray as a platform to distinguish these two tumors with the definitive diagnostic marker as well as the profiling of expression genes.

METHODS

In order to clarify the pathogenesis and find the biological markers for AT/RT, we established a derivative AT/RT primary cell culture. The differential profiling between AT/RT and MB were analyzed by using microarray method.

RESULTS

With the use of the microarray method, we demonstrated that 15 genes were significantly changed (at least 5-fold in upregulation and 1/5-fold in downregulation) between AT/RT and MB in tissues and cell lines. The quantitative reverse transcription-polymerase chain reaction analyses further confirmed that mRNA expression levels of SERPINI1 and osteopontin were highly expressed in AT/RT cells and tissues than those in MB. Importantly, our microarray result suggested that AT/RT presents the stemness-like pattern and expression profiling of embryonic stem cells as well as high mRNA expressions of Oct-4, Nanog, Sox-2, and c-Myc.

CONCLUSIONS

Our study demonstrated the differential gene expression profiling between AT/RT and MB. Based on the microarray findings, AT/RTs present embryonic stem-like gene recapitulation and further provide novel insights into their underlying biology.