Osteopontin overproduced by tumor cells acts as a potent angiogenic factor contributing to tumor growth

Assessing the role of Osteopontin in prognosis of oral squamous cell carcinoma- A systematic review

BACKGROUND

Oral cancer is always a global burden. It is the sixteenth most common cancer. It leads to metastasis since it is often diagnosed at late stages. To monitor the progress of this condition, various biomarkers are being utilized. Osteopontin is one such biomarker and its level in bodily fluids can be used as a reliable biomarker.

AIMS AND OBJECTIVES

The current study aims to review and evaluate the prognostic role of osteopontin in oral squamous cell carcinoma.

MATERIALS AND METHODS

A literature search was conducted across various databases such as Scopus, PubMed and Google Scholar. It yielded 18 articles totally using MeSH terms. The inclusion criteria were original research articles written only in English language involving both tissue and plasma osteopontin on oral cancer patients. Of these, only two articles which met the inclusion criteria were added into this systematic review. The search had no time restriction.

RESULTS

The studies showed that osteopontin play a vital role in the prognosis of the OSCC patients. One study from Taiwan and other from India proved the osteopontin expression in plasma and tissue can help to predict the prognosis of patients with oral cancer. Also, the level of plasma osteopontin was correlated with aggressiveness of OSCC. Tissue osteopontin expression was significantly lower in stage I OSCC patients when compared with stage II and III. Since there were only two studies, there is limited evidence of results.

CONCLUSION

From these findings, osteopontin can also be used as a reliable biomarker to predict the prognosis of oral cancer. Since there were only two studies to substantiate the finding, there is limited evidence and more studies are warranted to confirm the results.

Osteopontin promotes tumor microenvironment remodeling and therapy resistance

Osteopontin (OPN) is a multifunctional secretory protein which can be expressed and secreted by a variety of tumor cells and immune cells. Tumor microenvironment remodeling provides favorable conditions for tumor progression, immune escape and therapy resistance. As a bridge molecule in crosstalk between tumor cells and tumor microenvironment, OPN can not only come from tumor cells to regulate the functions of various immune cells, promoting the formation of immunosuppressive environment, but also can be secreted by immune cells to act on tumor cells, leading to tumor progression, thus constructing a positive feedback regulatory network. Here, we summarize the molecular structure, source and receptor of OPN, and clarify the mechanism of OPN on tumor-associated macrophages, dendritic cells, myeloid-derived suppressor cells, tumor progression and therapy resistance to comprehensively understand the great potential of OPN as a tumor biomarker and therapeutic target.

Cancer-associated fibroblast-derived secreted phosphoprotein 1 contributes to resistance of hepatocellular carcinoma to sorafenib and lenvatinib

BACKGROUND

Cancer-associated fibroblasts (CAFs) play an important role in the induction of chemo-resistance. This study aimed to clarify the mechanism underlying CAF-mediated resistance to two tyrosine kinase inhibitors (TKIs), sorafenib and lenvatinib, and to identify a novel therapeutic target for overcoming TKI resistance in hepatocellular carcinoma (HCC).

METHODS

We performed a systematic integrative analysis of publicly available gene expression datasets and whole-transcriptome sequencing data from 9 pairs of CAFs and para-cancer fibroblasts isolated from human HCC and para-tumor tissues, respectively, to identify key molecules that might induce resistance to TKIs. We then performed in vitro and in vivo experiments to validate selected targets and related mechanisms. The associations of plasma secreted phosphoprotein 1 (SPP1) expression levels before sorafenib/lenvatinib treatment with progression-free survival (PFS) and overall survival (OS) of 54 patients with advanced HCC were evaluated using Kaplan-Meier and Cox regression analysis.

RESULTS

Bioinformatic analysis identified CAF-derived SPP1 as a candidate molecule driving TKI resistance. SPP1 inhibitors reversed CAF-induced TKI resistance in vitro and in vivo. CAF-derived SPP1 activated rapidly accelerated fibrosarcoma (RAF)/mitogen-activated protein kinase (MAPK) and phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT)/mammalian target of rapamycin (mTOR) through the integrin-protein kinase C-alpha (PKCα) signaling pathway and promoted epithelial-to-mesenchymal transition (EMT). A high plasma SPP1 level before TKI treatment was identified as an independent predictor of poor PFS (P = 0.026) and OS (P = 0.047) in patients with advanced HCC after TKI treatment.

CONCLUSIONS

CAF-derived SPP1 enhances TKI resistance in HCC via bypass activation of oncogenic signals and EMT promotion. Its inhibition represents a promising therapeutic strategy against TKI resistance in HCC. Moreover, plasma SPP1 level before TKI treatment represents a potential biomarker for treatment response prediction.

Promising candidate cerebrospinal fluid biomarkers of seizure disorder, infection, inflammation, tumor, and traumatic brain injury in pediatric patients

Cerebrospinal fluid (CSF) is a dynamic metabolically active body fluid that has many important roles and is commonly analyzed in pediatric patients, mainly to diagnose central nervous system infection and inflammation disorders. CSF components have been extensively evaluated as biomarkers of neurological disorders in adult patients. Circulating microRNAs in CSF are a promising class of biomarkers for various neurological diseases. Due to the complexity of pediatric neurological disorders and difficulty in acquiring CSF samples from pediatric patients, there are challenges in developing CSF biomarkers of pediatric neurological disorders. This review aimed to provide an overview of novel CSF biomarkers of seizure disorders, infection, inflammation, tumor, traumatic brain injuries, intraventricular hemorrhage, and congenital hydrocephalus exclusively observed in pediatric patients.

Nanotechnology for angiogenesis: opportunities and challenges

Angiogenesis plays a critical role within the human body, from the early stages of life (i.e., embryonic development) to life-threatening diseases (e.g., cancer, heart attack, stroke, wound healing). Many pharmaceutical companies have expended huge efforts on both stimulation and inhibition of angiogenesis. During the last decade, the nanotechnology revolution has made a great impact in medicine, and regulatory approvals are starting to be achieved for nanomedicines to treat a wide range of diseases. Angiogenesis therapies involve the inhibition of angiogenesis in oncology and ophthalmology, and stimulation of angiogenesis in wound healing and tissue engineering. This review aims to summarize nanotechnology-based strategies that have been explored in the broad area of angiogenesis. Lipid-based, carbon-based and polymeric nanoparticles, and a wide range of inorganic and metallic nanoparticles are covered in detail. Theranostic and imaging approaches can be facilitated by nanoparticles. Many preparations have been reported to have a bimodal effect where they stimulate angiogenesis at low dose and inhibit it at higher doses.

Role of Matrix Vesicles in Bone-Vascular Cross-Talk

Matrix mineralization can be divided into physiological mineralization and pathological mineralization. There is a consensus among existing studies that matrix vesicles (MVs) are the starting sites of bone mineralization, and each component of MVs serves a certain function in mineralization. In addition, ectopic MVs pathologically promote undesired calcification, the primary focus of which is the promotion of vascular calcification. However, the specific mechanisms of the actions of MVs in bone-vascular axis cross-talk have not been fully elucidated. This review summarizes the latest research in this field and explores the roles of MVs in the bone-vascular axis with the aim of generating new ideas for the prevention and treatment of vascular calcification and bone metabolic disease.

Hypoxia-Inducible Factor-1α (HIF-1α) Expression on Endothelial Cells in Juvenile Nasopharyngeal Angiofibroma: A Review of 70 cases and Tissue Microarray Analysis

OBJECTIVE

To examine the expression of hypoxia-inducible factor-1α (HIF-1α) and its related molecules (cellular repressor of E1A-stimulated genes [CREG], osteopontin [OPN], proto-oncogene tyrosine-protein kinase Src [c-Src], and vascular endothelial growth factor [VEGF]) in juvenile nasopharyngeal angiofibroma (JNA) and explore the correlation between clinical prognosis and HIF-1α expression.

METHODS

The study performed a retrospective review of the clinical records of patients with JNA treated between 2003 and 2007. Specimens were analyzed by immunohistochemistry for HIF-1α, CREG, OPN, c-Src, and VEGF expression, and microvessel density (MVD) was assessed by tissue microarray. The correlation between expression levels and clinicopathological features including age, tumor stage, intraoperative blood loss, and recurrence was analyzed.

RESULTS

HIF-1α, CREG, OPN, c-Src, and VEGF were upregulated in endothelial cells (ECs) of patients with JNA, and strong correlations in the expression of these molecules were observed. HIF-1α expression was higher in young patients ( P = .032) and in recurrent cases ( P = .01). Survival analysis showed that low HIF-1α levels in ECs predicted longer time to recurrence (log rank test P = .006). Receiver operating characteristic curve analysis showed that HIF-1α was a prognostic factor for recurrence (area under the curve = 0.690, P = .019). No correlation was found between the expression of molecules and Radkowski stage or intraoperative blood loss.

CONCLUSION

In cases of JNA treated surgically, HIF-1α expression in ECs is a useful prognostic factor for tumor recurrence.

Osteopontin is involved in TLR4 pathway contributing to ovarian cancer cell proliferation and metastasis

Tumor cell proliferation and metastasis are critical for tumor progression and lead to death of cancer patients. TLR4 is a member of the toll-like receptor (TLR) family, which promotes tumor growth, metastasis and immune escape. Osteopontin (OPN), a phosphorylated glycoprotein extensively expressed in multiple cell-types, plays important roles in tumorigenesis, metastasis and infiltration, and participates in signal transduction of innate immunity. However, it is unclear whether TLR4 has any relationship with OPN. The current study investigated the role of TLR4 and OPN in tumor proliferation and metastasis, and the potential effect of TLR4 signaling on OPN using the human ovarian cancer cell line HO-8910PM. High expression levels of TLR4 and OPN were detected in HO-8910PM cells, which promoted the proliferation, migration and invasion of tumor cells. Lipopolysaccharide (LPS) induced activation of TLR4 up-regulated OPN, increasing the malignant phenotype of cells. RNAi-mediated knockdown of OPN reduced significantly the metastatic phenotype activated by TLR4. Taken together, our study demonstrates that OPN contributes to the ovarian cancer cell proliferation and metastasis, which is activated by TLR4 signaling pathway. It provides new insights for the mechanisms of tumor development and metastasis, and suggests targeting TLR4 and OPN as an intervention in the ovarian cancer treatment.

Runx3 and Cell Fate Decisions in Pancreas Cancer

The RUNX family transcription factors are critical regulators of development and frequently dysregulated in cancer. RUNX3, the least well characterized of the three family members, has been variously described as a tumor promoter or suppressor, sometimes with conflicting results and opinions in the same cancer and likely reflecting a complex role in oncogenesis. We recently identified RUNX3 expression as a crucial determinant of the predilection for pancreatic ductal adenocarcinoma (PDA) cells to proliferate locally or promulgate throughout the body. High RUNX3 expression induces the production and secretion of soluble factors that support metastatic niche construction and stimulates PDA cells to migrate and invade, while simultaneously suppressing proliferation through increased expression of cell cycle regulators such as CDKN1A/p21 ^WAF1/CIP1 . RUNX3 expression and function are coordinated by numerous transcriptional and post-translational inputs, and interactions with diverse cofactors influence whether the resulting RUNX3 complexes enact tumor suppressive or tumor promoting programs. Understanding these exquisitely context-dependent tumor cell behaviors has the potential to inform clinical decision-making including the most appropriate timing and sequencing of local vs. systemic therapies.

Pleural fluid osteopontin, vascular endothelial growth factor, and urokinase-type plasminogen activator levels as predictors of pleurodesis outcome and prognosticators in patients with malignant pleural effusion: a prospective cohort study

BACKGROUND

Rapidly growing cancer cells secrete growth-promoting polypeptides and have increased proteolytic activity, contributing to tumor progression and metastasis. Their presentation in malignant pleural effusion (MPE) and their predictive value for the outcome of pleurodesis and survival were studied.

METHODS

Between February 2011 and March 2012, MPE samples were prospectively collected from 61 patients. Twenty-five patients with non-malignant pleural effusion in the same period were included as controls. Pleural fluid osteopontin (OPN), vascular endothelial growth factor (VEGF), and urokinase-type plasminogen activator (uPA) concentrations were measured.

RESULTS

Patients with MPE had higher pleural fluid OPN, VEGF, and uPA concentrations than those with non-malignant pleural effusion, but only differences in VEGF were statistically significant (p = 0.045). Patients with distant metastases had significantly elevated pleural fluid VEGF concentrations than those without (p = 0.004). Pleural fluid OPN, VEGF, and uPA concentrations were positively correlated in most patients. However, there was no significant difference in pleural fluid OPN, VEGF, and uPA concentrations between patients with successful pleurodesis and those without. There was also no significant difference in cancer-specific survival between sub-groups with higher and lower pleural fluid OPN, VEGF, or uPA concentrations. Patients with successful pleurodesis had significantly longer cancer-specific survival than those without (p = 0.015).

CONCLUSIONS

Pleural fluid OPN, VEGF, and uPA concentrations are elevated in MPE but are not satisfactory predictors of pleurodesis outcome or survival. Patients with higher pleural fluid VEGF concentration have higher risk of distant metastasis. Evaluating the benefits of therapy targeting the VEGF pathway in these patients warrants further studies.

Tocilizumab, a proposed therapy for the cachexia of Interleukin6-expressing lung cancer

BACKGROUND

We previously reported the role of IL-6 in a murine model of cancer cachexia and currently documented a patient in whom tocilizumab, anti-IL-6 receptor antibody, dramatically improved cachexia induced by IL-6 over-expressing lung cancer. Despite this potential to alleviate cancer cachexia, tocilizumab has not been approved for this clinical use. Therefore, preceding our planned clinical trial of tocilizumab, we designed the two studies described here to evaluate the levels of IL-6 in patients with lung cancer and the effect of tocilizumab in a murine model of human cancer cachexia.

METHODS

First, we measured serum IL-6 levels in patients with lung cancer and analyzed its association with cachexia and survival. Next, we examined the effect of a rodent analog of tocilizumab (MR16-1) in the experimental cachexia model.

RESULTS

Serum IL-6 levels were higher in patients with cachexia than those without cachexia. In patients with chemotherapy-resistant lung cancer, a high IL-6 serum level correlated strongly with survival, and the cut-off level for affecting their prognosis was 21 pg/mL. Meanwhile, transplantation of IL-6-expressing Lewis Lung Carcinoma cells caused cachexia in mice, which then received either MR16-1 or 0.9% saline. Tumor growth was similar in both groups; however, the MR16-1 group lost less weight, maintained better food and water intake and had milder cachectic features in blood. MR16-1 also prolonged the survival of LLC-IL6 transplanted mice (36.6 vs. 28.5 days, p = 0.016).

CONCLUSION

Our clinical and experimental studies revealed that serum IL-6 is a surrogate marker for evaluating cachexia and the prognosis of patients with chemotherapy resistant metastatic lung cancer and that tocilizumab has the potential of improving prognosis and ameliorating the cachexia that so devastates their quality of life. This outcome greatly encourages our clinical trials to evaluate the safety and efficacy of tocilizumab treatment for patients with increased serum IL-6.

Inflammatory stress and sarcomagenesis: a vicious interplay

Chronic inflammation represents one of the hallmarks of cancer, but its role in sarcomagenesis has long been overlooked. Sarcomas are a rare and heterogeneous group of tumors of mesenchymal origin accounting for less than 1 % of cancers in adults but 21 % of cancers in the pediatric population. Sarcomas are associated with bad prognosis, and their management requires a multidisciplinary team approach. Several lines of evidence indicate that inflammation has been implicated in sarcomagenesis leading to the activation of the key transcription factors HIF-1, NF- κB, and STAT-3 involved in a complex inflammatory network. In the past years, an increasing number of new targets have been identified in the treatment of sarcomas leading to the development of new drugs that aim to interrupt the vicious connection between inflammation and sarcomagenesis. This article makes a brief overview of preclinical and clinical evidence of the molecular pathways involved in the inflammatory stress response in sarcomagenesis and the most targeted therapies.

The role of inflammation in sarcoma

Sarcomas encompass a heterogenous group of tumors with diverse pathologically and clinically overlapping features. It is a rarely curable disease, and their management requires a multidisciplinary team approach. Chronic inflammation has emerged as one of the hallmarks of tumors including sarcomas. Classical inflammation-associated sarcomas comprise the inflammatory malignant fibrous histiocytoma and Kaposi sarcoma. The identification of specific chromosomal translocations and important intracellular signaling pathways such as Ras/Raf/MAPK, insulin-like growth factor, PI3K/AKT/mTOR, sonic hedgehog and Notch together with the increasing knowledge of angiogenesis has led to development of targeted therapies that aim to interrupt these pathways. Innovative agents like oncolytic viruses opened the way to design new therapeutic options with encouraging findings. Preclinical evidence also highlights the therapeutic potential of anti-inflammatory nutraceuticals as they can inhibit multiple pathways while being less toxic. This chapter gives an overview of actual therapeutic standards, newest evidence-based studies and exciting options for targeted therapies in sarcomas.

Serum levels of osteopontin as a prognostic factor in patients with oral squamous cell carcinoma

Osteopontin (OPN) is a multifunctional glycophosphoprotein that was detected in many carcinomas, and it may have a prognostic role. The aim of this study was to determine osteopontin serum levels in patients with oral squamous cell carcinoma (OSCC) and investigated its correlation with clinicopathological features of tumor. Using an ELISA kit, we assessed and compared the circulating levels of OPN in blood serum of 45 oral squamous cell carcinoma patients with 45 healthy control samples. The serum osteopontin level in patients with OSCC was significantly higher (145.8 ± 14.6 ng/ml, n = 45) compared with the healthy controls (53.9 ± 9.6 ng/ml, n = 45, p < 0.001). Mean serum osteopontin level was significantly higher in patients with nodal metastasis (p = 0.03) and higher stage (p = 0.02). Findings of the present study suggest that OPN may have a potential role in pathogenesis of OSCC and it may be used as a tool for monitoring tumor progression.

Expression and regulation of secreted phosphoprotein 1 in the bovine corpus luteum and effects on T lymphocyte chemotaxis

Secreted phosphoprotein 1 (SPP1) in the bovine corpus luteum (CL) regulates cell function during the transitional periods of luteinization and luteal regression. The objectives were to i) characterize SPP1 expression in the CL throughout the estrous cycle, ii) determine factors that regulate SPP1 expression in luteal cells, and iii) examine the role of SPP1 in lymphocyte chemotaxis, proliferation, and function. SPP1 mRNA was greater in fully functional (d10) CL and late cycle (d18) CL compared with developing (d4) CL. Additionally, SPP1 mRNA increased within 1 h and remained elevated 4 and 8 h following induction of luteolysis with prostaglandin (PG)F2α. Expression of the SPP1 receptor, β3 integrin, was not different throughout the estrous cycle but decreased following induction of luteolysis. Expression of CD44 increased during the estrous cycle but did not change during luteal regression. In cultured luteal cells, SPP1 mRNA was upregulated by PGF2α and/or tumor necrosis factor α. Western blots revealed the presence of both full-length SPP1 and multiple cleavage products in cultured luteal cells and luteal tissue. Depletion of endogenous SPP1 did not hinder luteal cell-induced lymphocyte proliferation or lymphocyte phenotype but did inhibit lymphocyte migration toward luteal cells. Based on these data, it is concluded that SPP1 is initially activated to establish and maintain cellular interactions between steroidogenic and nonsteroidogenic cells during the development of the CL. Upon induction of luteolysis, SPP1 serves as a signaling molecule to recruit or activate immune cells to facilitate luteal regression and tissue degradation.

Biomarkers of pediatric brain tumors

Background and Need for Novel Biomarkers: Brain tumors are the leading cause of death by solid tumors in children. Although improvements have been made in their radiological detection and treatment, our capacity to promptly diagnose pediatric brain tumors in their early stages remains limited. This contrasts several other cancers where serum biomarkers such as cancer antigen (CA) 19-9 and CA 125 facilitate early diagnosis and treatment.

AIM

The aim of this article is to review the latest literature and highlight biomarkers which may be of clinical use in the common types of primary pediatric brain tumor.

METHODS

A PubMed search was performed to identify studies reporting biomarkers in the bodily fluids of pediatric patients with brain tumors. Details regarding the sample type [serum, cerebrospinal fluid (CSF), or urine], biomarkers analyzed, methodology, tumor type, and statistical significance were recorded.

RESULTS

A total of 12 manuscripts reporting 19 biomarkers in 367 patients vs. 397 controls were identified in the literature. Of the 19 biomarkers identified, 12 were isolated from CSF, 2 from serum, 3 from urine, and 2 from multiple bodily fluids. All but one study reported statistically significant differences in biomarker expression between patient and control groups.

CONCLUSION

This review identifies a panel of novel biomarkers for pediatric brain tumors. It provides a platform for the further studies necessary to validate these biomarkers and, in addition, highlights several techniques through which new biomarkers can be discovered.

Elevated circulating levels of osteopontin are associated with metastasis in advanced non-small cell lung cancer

OBJECTIVE

To investigate the relationship between postoperative metastasis and circulating levels of osteopontin in non-small cell lung cancer (NSCLC).

METHODS

The expression of osteopontin mRNA were detected with RT-PCR technique. The circulating levels of osteopontin were measured through ELASA in 46 NSCLC cases that had not been received any anti-cancer treatment at the time of sampling. The tissues from fifteen patients with benign pulmonary diseases were studied as control group.

RESULTS

The overall median mRNA expression level of osteopontin was approximately 70-fold higher in tumor tissues than in matched normal lung tissues (P<0.001). Over-expression of osteopontin mRNA was significantly associated with clinical stage (P=0.009). Advanced disease states had higher circulating level of osteopontin (stage I+II versus stage III+VI). In multivariate analysis, stage was the only independent factor influencing circulating levels of osteopontin. All patients were followed up for 12 months, 2 of the 46 patients with both osteopontin mRNA expression and elevated plasma osteopontin levels had local recurrence and 10 had distant metastasis. There was a significant difference in the osteopontin levels between metastasis group and non-metastasis group.

CONCLUSION

Preoperative plasma levels of osteopontin are significantly associated with post-operative metastasis in advanced NSCLC.

Emerging avenues linking inflammation and cancer

The role of inflammation in carcinogenesis has been extensively investigated and well documented. Many biochemical processes that are altered during chronic inflammation have been implicated in tumorigenesis. These include shifting cellular redox balance toward oxidative stress; induction of genomic instability; increased DNA damage; stimulation of cell proliferation, metastasis, and angiogenesis; deregulation of cellular epigenetic control of gene expression; and inappropriate epithelial-to-mesenchymal transition. A wide array of proinflammatory cytokines, prostaglandins, nitric oxide, and matricellular proteins are closely involved in premalignant and malignant conversion of cells in a background of chronic inflammation. Inappropriate transcription of genes encoding inflammatory mediators, survival factors, and angiogenic and metastatic proteins is the key molecular event in linking inflammation and cancer. Aberrant cell signaling pathways comprising various kinases and their downstream transcription factors have been identified as the major contributors in abnormal gene expression associated with inflammation-driven carcinogenesis. The posttranscriptional regulation of gene expression by microRNAs also provides the molecular basis for linking inflammation to cancer. This review highlights the multifaceted role of inflammation in carcinogenesis in the context of altered cellular redox signaling.

Pretreatment of endothelial progenitor cells with osteopontin enhances cell therapy for peripheral vascular disease

Tissue necrosis resulting from critical limb ischemia (CLI) leads to amputation in a significant number of patients. Autologous cell therapy using angiogenic cells such as endothelial progenitor cells (EPCs) holds promise as a treatment for CLI but a limitation of this treatment is that the underlying disease etiology that resulted in CLI may also contribute to dysfunction of the therapeutic EPCs. This study aimed to elucidate the mechanism of EPC dysfunction using diabetes mellitus as a model and to determine whether correction of this defect in dysfunctional EPCs ex vivo would improve the outcome after cell transplantation in the murine hind limb ischemia model. EPC dysfunction was confirmed in a homogenous population of patients with type 1 diabetes mellitus and a microarray study was preformed to identify dysregulated genes. Notably, the secreted proangiogenic protein osteopontin (OPN) was significantly downregulated in diabetic EPCs. Furthermore, OPN-deficient mice showed impaired recovery following hind limb ischemia, suggesting a critical role for OPN in postnatal neovascularization. EPCs isolated from OPN KO mice showed decreased ability to adhere to endothelial cells as well as impaired angiogenic potential. However, this dysfunction was reversed upon exposure to recombinant OPN, suggesting that OPN may act in an autocrine manner on EPCs. Indeed, exposure of OPN knockout (KO) EPCs to OPN was sufficient to induce the secretion of angiogenic proteins (IL-6, TGF-α, and FGF-α). We also demonstrated that vascular regeneration following hind limb ischemia in OPN KO mice was significantly improved upon injection of EPCs preexposed to OPN. We concluded that OPN acts in an autocrine manner on EPCs to induce the secretion of angiogenic proteins, thereby playing a critical role in EPC-mediated neovascularization. Modification of cells by exposure to OPN may improve the efficacy of autologous EPC transplantation via the enhanced secretion of angiogenic proteins.

Targeting angiogenesis for controlling neuroblastoma

Neuroblastoma, a progressive solid tumor in childhood, continues to be a clinical challenge. It is highly vascular, heterogeneous, and extracranial tumor that originates from neural crest. Angiogenesis, genetic abnormalities, and oncogene amplification are mainly responsible for malignant phenotype of this tumor. Survivability of malignant neuroblastoma patients remains poor despite the use of traditional therapeutic strategies. Angiogenesis is a very common and necessary pre-requisite for tumor progression and metastasis. Angiogenesis is also a major factor in making malignant neuroblastoma. Thus, prevention of angiogenesis can be a highly significant strategy in the treatment of malignant neuroblastoma. Here, we summarize our current understanding of angiogenesis in malignant neuroblstoma and describe the use of experimental anti-angiogenic agents either alone or in combination therapy. This review will clearly indicate the importance of angiogenesis in the pathogenesis of malignant neuroblastoma, its prevention as a promising therapy in preclinical models of malignant neuroblastoma, and prospective clinical trials.

Angiogenesis and multiple myeloma

The bone marrow microenvironment in multiple myeloma is characterized by an increased microvessel density. The production of pro-angiogenic molecules is increased and the production of angiogenic inhibitors is suppressed, leading to an "angiogenic switch". Here we present an overview of the role of angiogenesis in multiple myeloma, the pro-angiogenic factors produced by myeloma cells and the microenvironment, and the mechanisms involved in the myeloma-induced angiogenic switch. Current data suggest that the increased bone marrow angiogenesis in multiple myeloma is due to the aberrant expression of angiogenic factors by myeloma cells, the subsequent increase in pro-angiogenic activity of normal plasma cells as a result of myeloma cell angiogenic activity, and the increased number of plasma cells overall. Hypoxia also contributes to the angiogenic properties of the myeloma marrow microenvironment. The transcription factor hypoxia-inducible factor-1α is overexpressed by myeloma cells and affects their transcriptional and angiogenic profiles. In addition, potential roles of the tumor suppressor gene inhibitor of growth family member 4 and homeobox B7 have also been recently highlighted as repressors of angiogenesis and pro-angiogenic related genes, respectively. This complex pathogenetic model of myeloma-induced angiogenesis suggests that several pro-angiogenic molecules and related genes in myeloma cells and the microenvironment are potential therapeutic targets.

Corn baked by burning coal triggered overexpression of osteopontin in hepatocytes of rats following fluorosis

Objective: To observe the expression of osteopontin (OPN) in hepatocytes of rats fed with corn baked by burning coal from fluorosis areas and a deficiency of calcium/protein intake following fluorosis. Methods: A total of 48 Wistar rats as objects were randomly assorted into four groups: dose-free fluorine group, which were mainly fed with fluorine-free corn (56% structurally), dose-free fluorine with biased dietary group, which were fed with lower contents of protein (119.41 g/kg) and calcium (0.68 g/kg), high-dose fluorine group (fluorine contents: 104.2 mg/kg), and high-dose fluorine with biased dietary group. After 180 days of cultivation, the contents of fluorine in the bones of rats were tested for the assessment of construction of fluorosis animal model. And the expression of OPN in hepatocytes of rats in different groups was detected with immunohistochemistry and reverse transcription polymerase chain reaction. Results: The present study validated the result that OPN was overexpressed in hepatocytes following fluorosis after oral intake of burning coal-baked corn. OPN was expressed most significantly in high fluorine with biased dietary group, and the high-fluorine group ranked the second most; and dose-free fluorine with biased dietary group ranked the third. The dose-free fluorine group expressed the least OPN. Conclusion: Overexpression of OPN in hepatocytes following fluorosis after excess fluorine intake was involved in liver damage process, which was enhanced by deficiency of calcium and protein intake. The results also demonstrated that the development of fluorosis in Guizhou province was correlated with local baking staple corn as a way of excess intake of fluorine and deficiency of calcium/protein intake.

Deletion of the thrombin cleavage domain of osteopontin mediates breast cancer cell adhesion, proteolytic activity, tumorgenicity, and metastasis

BACKGROUND

Osteopontin (OPN) is a secreted phosphoprotein often overexpressed at high levels in the blood and primary tumors of breast cancer patients. OPN contains two integrin-binding sites and a thrombin cleavage domain located in close proximity to each other.

METHODS

To study the role of the thrombin cleavage site of OPN, MDA-MB-468 human breast cancer cells were stably transfected with either wildtype OPN (468-OPN), mutant OPN lacking the thrombin cleavage domain (468-ΔTC) or an empty vector (468-CON) and assessed for in vitro and in vivo functional differences in malignant/metastatic behavior.

RESULTS

All three cell lines were found to equivalently express thrombin, tissue factor, CD44, αvβ5 integrin and β1 integrin. Relative to 468-OPN and 468-CON cells, 468-ΔTC cells expressing OPN with a deleted thrombin cleavage domain demonstrated decreased cell adhesion (p < 0.001), decreased mRNA expression of MCAM, maspin and TRAIL (p < 0.01), and increased uPA expression and activity (p < 0.01) in vitro. Furthermore, injection of 468-ΔTC cells into the mammary fat pad of nude mice resulted in decreased primary tumor latency time (p < 0.01) and increased primary tumor growth and lymph node metastatic burden (p < 0.001) compared to 468-OPN and 468-CON cells.

CONCLUSIONS

The results presented here suggest that expression of thrombin-uncleavable OPN imparts an early tumor formation advantage as well as a metastatic advantage for breast cancer cells, possibly due to increased proteolytic activity and decreased adhesion and apoptosis. Clarification of the mechanisms responsible for these observations and the translation of this knowledge into the clinic could ultimately provide new therapeutic opportunities for combating breast cancer.

Elevated osteopontin expression and proliferative/apoptotic ratio in the colorectal adenoma-dysplasia-carcinoma sequence

Colorectal cancer progression is characterized by altered epithelial proliferation and apoptosis and by changed expression of tumor development regulators. Our aims were to determine the proliferative/apoptotic epithelial cell ratio (PAR) in the adenoma-dysplasia-carcinoma sequence (ADCS), and to examine its association with osteopontin (OPN), a previously identified protein product related to cancer development. One mm diameter cores from 13 healthy colons, 13 adenomas and 13 colon carcinoma samples were included into a tissue microarray (TMA) block. TUNEL reaction and Ki-67 immunohistochemistry were applied to determine the PAR. The osteopontin protein was also immunodetected. Stained slides were semiquantitatively evaluated using digital microscope and statistically analyzed with logistic regression and Fisher's exact test. The PAR continuously increased along the ADCS. It was significantly (p < 0.001) higher in cancer epithelium (8.84 ± 7.01) than in adenomas (1.40 ± 0.78) and in normal controls (0.89 ± 0.21) (p < 0.001). Also, significant positive correlation was observed between elevated PAR and the expression of osteopontin. Cytoplasmic OPN expression was weak in healthy samples. In contrast, cytoplasmic immunoreaction was moderately intensive in adenomas, while in colon cancer strong, diffuse cytoplasmic immune staining was detected. Increasing PAR and OPN expression along ADCS may help monitoring colorectal cancer progression. The significantly elevated OPN protein levels we found during normal epithelium to carcinoma progression may contribute to the increased fibroblast-myofibroblast transition determining stem cell niche in colorectal cancer.

Matricellular proteins: from homeostasis to inflammation, cancer, and metastasis

The family of matricellular proteins comprises molecules with disparate biology. The main characteristic of matricellular proteins is to be expressed during tissue renewal and repair in order to "normalize" the tissue. Tumors are wound that do not heal, and tumor growth and metastasis can be viewed as a consequence of aberrant homeostasis, during which matricellular proteins are often upregulated. In the tumor microenvironment, they can be produced by both tumor cells and surrounding stromal cells, such as fibroblasts and macrophages. In this context, matricellular proteins can exert several functions that actively contribute to tumor progression. They may (a) regulate cellular adhesion and migration and extracellular matrix deposition, (b) control tumor infiltration by macrophages or other leukocytes, (c) affect tumor angiogenesis, (d) regulate TGFbeta and other growth factor receptor signals, (e) directly stimulate integrin receptors to transduce pro-survival or pro-migratory signals, and (f) regulate the wnt/beta-catenin pathways. Most of these functions contribute to settle a chronic low inflammatory state, whose involvement in tissue transformation and tumor progression is now established.

A short-hairpin RNA targeting osteopontin downregulates MMP-2 and MMP-9 expressions in prostate cancer PC-3 cells

Osteopontin (OPN), a secreted phosphoglycoprotein, is frequently associated with cell proliferation and tumor metastatic spread in a variety of cancers. It has been reported that OPN induce matrix metalloproteinase (MMP)-2 and MMP-9 activations through nuclear factor kappaB (NF-kappaB)-mediated signaling pathways. In this study, we investigated the roles of OPN in human prostate cancer cells and provided clues about the possible functions of IkappaB kinase (IKK) in NF-kappaB-mediated OPN-induced activations of MMP-2 and MMP-9. Short-hairpin RNA (shRNA) expression vectors were used to inhibit OPN expression in PC-3 cells, human prostate cancer cell line, and IKK inhibitor VII were applied to inhibit the activities of IKK-1 and IKK-2. The results showed that OPN shRNA-mediated RNA interference can downregulate OPN, MMP-2 and MMP-9 expressions, thereby resulting in suppression of the proliferation, migration and invasion of PC-3 cells in vitro and tumor growth in vivo. Moreover, the inhibition of IKK-2 can suppress MMP-2 and MMP-9 expressions, in contrast, the inhibition of IKK-1 has no effects on the OPN, MMP-2 and MMP-9 expression levels. Thus, this study demonstrated that OPN knockdown could downregulate MMP-2 and MMP-9 expressions result in inhibiting the malignant physiological behaviors of PC-3 cell and that IKK-2 may play a crucial role in OPN-induced MMP-2 and MMP-9 expressions via NF-kappaB-mediated signaling pathways.

Hypoxia-regulated delta-like 1 homologue enhances cancer cell stemness and tumorigenicity

Reduced oxygenation, or hypoxia, inhibits differentiation and facilitates stem cell maintenance. Hypoxia commonly occurs in solid tumors and promotes malignant progression. Hypoxic tumors are aggressive and exhibit stem cell-like characteristics. It remains unclear, however, whether and how hypoxia regulates cancer cell differentiation and maintains cancer cell stemness. Here, we show that hypoxia increases the expression of the stem cell gene DLK1, or delta-like 1 homologue (Drosophila), in neuronal tumor cells. Inhibition of DLK1 enhances spontaneous differentiation, decreases clonogenicity, and reduces in vivo tumor growth. Overexpression of DLK1 inhibits differentiation and enhances tumorigenic potentials. We further show that the DLK1 cytoplasmic domain, especially Tyrosine339 and Serine355, is required for maintaining both clonogenicity and tumorigenicity. Because elevated DLK1 expression is found in many tumor types, our observations suggest that hypoxia and DLK1 may constitute an important stem cell pathway for the regulation of cancer stem cell-like functionality and tumorigenicity.

Release characteristics and osteogenic activity of recombinant human bone morphogenetic protein-2 grafted to novel self-assembled poly(lactide-co-glycolide fumarate) nanoparticles

Functionalized biodegradable nanoparticles (NPs) provide reactive groups and large surface area for grafting recombinant human bone morphogenetic protein-2 (rhBMP-2) to reduce protein diffusion and maintain sufficient concentration for recruitment and differentiation of osteoprogenitor cells. The objective of this work was to investigate release characteristics and osteogenic activity of rhBMP-2, grafted to biodegradable NPs based on succinimide-terminated poly(lactide fumarate) (PLAF-NHS) and poly(lactide-co-glycolide fumarate) (PLGF-NHS) macromers. The release of rhBMP-2 from the NPs, measured by enzyme-linked immunosorbent assay, was linear with time in the first two weeks, and 24.70+/-1.30% and 48.7+/-0.7% of the protein grafted to PLGF-NHS and PLAF-NHS NPs, respectively, was released in the enzymatically active conformation after complete degradation/erosion of the NPs. After 14 days of incubation with bone marrow stromal (BMS) cells, rhBMP-2 grafted to PLAF-NHS and PLGF-NHS NPs was as effective in inducing mineralization as the native rhBMP-2 that was directly added to the cell culture media. At any incubation time, rhBMP-2 grafted to PLAF had the highest expression of osteopontin (OP) and osteocalcin (OC), followed by rhBMP-2 grafted to PLGF and rhBMP-2 directly added to media. Higher OP and OC expression for BMP-gPLAF and BMP-gPLGF groups may be related to other factors in the cascade of osteogenesis, such as differentiation of BMS cells to the vasculogenic lineage and formation of a vascularized/mineralized matrix.

Differential secreted proteome approach in murine model for candidate biomarker discovery in colon cancer

The complexity and heterogeneity of the plasma proteome have presented significant challenges in the identification of protein changes associated with tumor development. We used cell culture as a model system and identified differentially expressed, secreted proteins which may constitute serological biomarkers. A stable isotope labeling by amino acids in cell culture (SILAC) approach was used to label the entire secreted proteomes of the CT26 murine colon cancer cell line and normal young adult mouse colon (YAMC) cell line, thereby creating a stable isotope labeled proteome (SILAP) standard. This SILAP standard was added to unlabeled murine CT26 colon cancer cell or normal murine YAMC colon epithelial cell secreted proteome samples. A multidimensional approach combining isoelectric focusing (IEF), strong cation exchange (SCX) followed by reversed phase liquid chromatography was used for extensive protein and peptide separation. A total of 614 and 929 proteins were identified from the YAMC and CT26 cell lines, with 418 proteins common to both cell lines. Twenty highly abundant differentially expressed proteins from these groups were selected for liquid chromatography-multiple reaction monitoring/mass spectrometry (LC-MRM/MS) analysis in sera. Differential secretion into the serum was observed for several proteins when Apc(min) mice were compared with control mice. These findings were then confirmed by Western blot analysis.

Osteopontin expression in pulmonary tumor thrombotic microangiopathy caused by gastric carcinoma

Pulmonary tumor thrombotic microangiopathy (PTTM) is characterized by fibrocellular intimal proliferation and thrombus formation in small pulmonary arteries and arterioles in patients with metastatic carcinoma. Osteopontin (OPN) is a multifunctional cytokine and adhesive protein, and has been demonstrated to be implicated in fibrosis, neointima formation, arterial occlusion by thrombus, and tumor metastases in cooperation with platelet-derived growth factor (PDGF) and vascular endothelial growth factor (VEGF). Herein is described an autopsy case of gastric adenocarcinoma with severe pulmonary hypertension due to PTTM. Histologically, tumor cell emboli markedly induced both fibromuscular intimal thickening and thrombosis, resulting in luminal stenosis and occlusion of small pulmonary arteries and arterioles. Tumor cells, both in the PTTM lesions and primary gastric carcinoma, had positive immunoreactivity for OPN, PDGF, and VEGF. In addition, proliferating fibromuscular intimal cells also showed expression of OPN, PDGF, and VEGF. These findings suggest that OPN may be involved in fibrocellular intimal proliferation and thrombus formation in PTTM together with PDGF and VEGF. To the best of the authors' knowledge this is the first report to demonstrate the possible involvement of OPN in PTTM. It is postulated that OPN is one of the candidate molecules for the development of PTTM.

Transactivation of human osteopontin promoter by human T-cell leukemia virus type 1-encoded Tax protein

Osteopontin (OPN) is a cytokine that contributes substantially to the growth and metastasis in a wide spectrum of malignancies. We report here that OPN gene is transactivated by Tax protein of human T-cell leukemia virus type 1 (HTLV-1). Northern blot showed enhanced OPN gene expression in cells stably expressing Tax. Co-expression of Tax increased the reporter gene expression directed by OPN promoter. Tax-induced OPN activation was abrogated by treatment with LY294002 (PI3K inhibitor) or co-transfection with AKT siRNA, suggesting PI3K/AKT pathway is involved in Tax-mediated transactivation. Reporter assay with deletion mutants showed that the 5'-partial sequence between -765 and -660 of the OPN promoter is the region responsive to Tax, and further, disrupting the AP-1 site within this region abolished the OPN induction by Tax, indicating that Tax activation of OPN promoter is likely mediated by AP-1 site. This study suggests that OPN is one of the downstream mediators of aberrantly activated PI3K/AKT signaling by Tax, which may partially contribute to HTLV-1-associated leukemogenesis.

Spheroid-forming subpopulation of breast cancer cells demonstrates vasculogenic mimicry via hsa-miR-299-5p regulated de novo expression of osteopontin

The growth of cancer cells as multicellular spheroids has frequently been reported to mimic the in vivo tumour architecture and physiology and has been utilized to study antitumour drugs. In order to determine the distinctive characteristics of the spheroid-derived cells compared to the corresponding monolayer-derived cells, we enriched multicellular spheroid-forming subpopulations of cells from three human breast cancer cell lines (MCF7, MCF10AT and MCF10DCIS.com). These spheroid-derived cells were injected into female athymic nude mice to assess their tumorigenic potential and were profiled for their characteristic miRNA signature. We discovered that the spheroid-derived cells expressed increased levels of osteopontin (OPN), an oncogenic protein that has been clinically correlated with increased tumour burden and adverse prognosis in patients with breast cancer metastasis. Our studies further show that increased OPN levels are brought about in part, by decreased levels of hsa-mir-299–5p in the spheroid-forming population from all three cell lines. Moreover, the spheroid-forming cells can organize into vascular structures in response to nutritional limitation; these structures recapitulate a vascular phenotype by the expression of endothelial markers CD31, Angiopoeitin-1 and Endoglin. In this study, we have validated that hsa-mir-299–5p targets OPN; de novo expression of OPN in turn plays a critical role in enhancing proliferation, tumorigenicity and the ability to display vasculogenic mimicry of the spheroid-forming cells.

Novel anti-myeloma agents and angiogenesis

During the last decade several novel agents have been used in the management of patients with multiple myeloma. Immunomodulatory drugs and proteasome inhibitors exert their efficacy both directly by inducing apoptosis of myeloma cells and indirectly through the interruption of the interactions between myeloma and stromal cells in the bone marrow (BM) microenvironment. These interactions are crucial for myeloma cell growth and survival. The adherence of myeloma cells to BM stromal cells leads to the overproduction of several cytokines with angiogenic properties that enhance the survival and growth of myeloma cells through paracrine and autocrine loops. The correlation of these molecules with clinical features and survival of myeloma patients supports the importance of angiogenesis in the pathogenesis of the disease and reveals these cytokines as suitable targets for the development of novel anti-myeloma therapies. This review summarises all available preclinical and clinical data for the effect of novel agents that are used in myeloma therapy, such as thalidomide, lenalidomide, bortezomib and VEGF inhibitors, on angiogenesis, which is at least partially responsible for their remarkable anti-myeloma efficacy.

Progesterone and placentation increase secreted phosphoprotein one (SPP1 or osteopontin) in uterine glands and stroma for histotrophic and hematotrophic support of ovine pregnancy

Secreted phosphoprotein one (SPP1, osteopontin) may regulate conceptus implantation and placentation. We investigated effects of progesterone (P(4)) and the conceptus on expression and localization of SPP1 in the ovine uterus. Steady-state levels of SPP1 mRNA in the endometrium of unilaterally pregnant ewes did not differ significantly between nongravid and gravid horns within their respective days of pregnancy; however, levels did increase as pregnancy progressed. SPP1 mRNA was detectable in the glandular epithelium (GE) of both nongravid and gravid horns via in situ hybridization. SPP1 protein was localized to the apical surface of the luminal epithelium of both nongravid and gravid uterine horns. Gravid horns exhibited extensive stromal SPP1 on Days 40 through 120, whereas SPP1 was markedly lower in the stroma of nongravid uterine horns through Day 80 of pregnancy. By Day 120, stromal expression of SPP1 between nongravid and gravid horns was similar. Long-term P(4) treatment of ovariectomized ewes induced SPP1 in the uterine stroma and GE. A bioactive 45-kDa SPP1 fragment was purified from uterine secretions and promoted ovine trophectoderm cell attachment in vitro. Interestingly, increased stromal cell expression of SPP1 was positively associated with vascularization as assessed by von Willebrand factor staining. Finally, ovine uterine artery endothelial cells produced SPP1 during outgrowth into three-dimensional collagen matrices in an in vitro model system that recapitulates angiogenesis. Collectively, P(4) induces and the conceptus further stimulates SPP1 in uterine GE and stroma, where SPP1 likely influences histotrophic and hematotrophic support of conceptus development.

Osteopontin: regulation in tumor metastasis

Osteopontin is a secreted phosphoprotein that has been implicated as an important mediator of tumor metastasis and has been investigated for use as a biomarker for advanced disease and as a potential therapeutic target in the regulation of cancer metastasis. The OPN DNA sequence is highly conserved and the protein contains several important functional domains including alpha(v)beta integrin and CD44 binding sites. High levels of OPN expression correlate with tumor invasion, progression or metastasis in multiple cancer. Studies demonstrate that osteopontin mediates the molecular mechanisms which determine metastatic spread, such as prevention of apoptosis, extracellular matrix proteolysis and remodeling, cell migration, evasion of host-immune cells and neovascularization. Transcriptional regulation of OPN is complex and involves multiple pathways, including AP-1, Myc, v-Src, Runx/CBF, TGF-B/BMPs/Smad/Hox, and Wnt/ss-catenin/APC/GSK-3ss/Tcf-4. The current state of knowledge of OPN biology suggests that it is an attractive target for therapeutic modulation of metastatic disease.

Down-regulation of osteopontin attenuates breast tumour progression in vivo

Development of breast tumour malignancies results in enhanced expression of various oncogenic molecules. Elevated expression of osteopontin (OPN) in higher grades of breast carcinoma correlates with enhanced expressions of several oncogenic molecules (urokinase-type plasminogen activator [uPA], matrix metalloproteinase-2/-9 [MMP-2 and -9]) and increased angiogenic potential of breast carcinoma. In this study, using in vitro and multiple in vivo models, we have demonstrated that silencing of OPN by its specific small interfering RNA (siRNA) down-regulates the expressions of oncogenic molecules such as uPA, MMP-2 and -9 resulting in inhibition of in vitro cell motility and in vivo tumourigenicity in mice. Moreover our results demonstrated that OPN^−/− mice showed slower progression of tumour growth in breast cancer model as compared to wild-type mice. Furthermore, the data showed that injection of carcinogenic compound, pristane (2, 6,10,14-tetramethylpen-tadecane) induces breast tumour progression leading to enhanced expression of OPN and other oncogenic molecules in mammary fat pad of nude- and wild-type mice but not in OPN^−/ mice. However, intratumoural injection of OPN siRNA to pristane-induced tumour significantly suppressed these effects. Our data revealed that knocking down of OPN effectively curb breast cancer progression and further suggested that developing of OPN-based therapeutics might be an emerging approach for the next generation of breast cancer management.

Positive correlation of osteopontin, cyclooxygenase-2 and vascular endothelial growth factor in gastric cancer

Osteopontin (OPN), cyclooxygenase-2 (COX-2) and vascular endothelial growth factor (VEGF) are overexpressed in various experimental models of malignancy. However, the correlation and role of the three molecules in gastric cancer is unclear. In the present study, we found that OPN, COX-2 and VEGF were overexpressed in 53 cancerous tissues with gastric cancer compared with 40 normal mucosa tissues by immunohistochemistry method. Moreover, the results indicated co-expression of OPN, COX-2, and VEGF in gastric cancer. Levels of OPN, COX-2, and VEGF were all significantly correlated with TNM stage, lymph node metastasis and distant metastasis (P < 0.05), while not related to prognosis of patients. In addition, individual levels of OPN, COX-2, and VEGF were all significantly correlated with microvessel density (MVD), valued by CD34 staining directly with r-values of 0.416, 0.400, and 0.566, respectively (P < 0.01). Both OPN and COX-2 levels showed a positive correlation with VEGF (P < 0.05). Meanwhile, expression of COX-2 is in relation to OPN (P < 0.01). Overall, survival for patients with high MVD was significantly lower than for patients with low MVD (P < 0.05). Our findings indicate that OPN, COX-2, and VEGF synergically promote angiogenesis and metastasis in gastric cancer. It may be an important and useful strategy to target these molecules for prevention and therapy of tumor.

Inhibition of osteopontin would suppress angiogenesis in gastric cancer

Osteopontin (OPN) plays an important role in tumorigenesis, tumor invasion, and metastasis in many types of cancers, including gastric cancer. Recently, much interest has been focused on the role of OPN in tumor angiogenesis. Our previous studies have shown that OPN is overexpressed, and associated with mean microvessel density in, the tissue samples of patients with gastric cancer. In the present study, we aimed to further determine and provide evidence for the role of OPN in gastric-cancer-associated angiogenesis by diminishing OPN expression in gastric cancer cells using the small interference RNA method, and then evaluate the effects of OPN on gastric cancer-associated angiogenesis by in vivo and in vitro assays. Our results revealed that reduced OPN production by gastric cancer cells would reduce the proliferation, migration, and tube formation of human umbilical vein endothelial cells, and lead to a lower microvessel density, i.e., angiogenesis, in transplanted tumors of mice. These data confirm the positive role of OPN in gastric-cancer-associated angiogenesis.

The new tumor-suppressor gene inhibitor of growth family member 4 (ING4) regulates the production of proangiogenic molecules by myeloma cells and suppresses hypoxia-inducible factor-1 alpha (HIF-1alpha) activity: involvement in myeloma-induced angiogenesis

Angiogenesis has a critical role in the pathophysiology of multiple myeloma (MM); however, the molecular mechanisms underlying this process are not completely elucidated. The new tumor-suppressor gene inhibitor of growth family member 4 (ING4) has been recently implicated in solid tumors as a repressor of angiogenesis. In this study, we found that ING4 expression in MM cells was correlated with the expression of the proangiogenic molecules interleukin-8 (IL-8) and osteopontin (OPN). Moreover, we demonstrate that ING4 suppression in MM cells up-regulated IL-8 and OPN, increasing the hypoxia inducible factor-1alpha (HIF-1alpha) activity and its target gene NIP-3 expression in hypoxic condition. In turn, we show that the inhibition of HIF-1alpha by siRNA suppressed IL-8 and OPN production by MM cells under hypoxia. A direct interaction between ING4 and the HIF prolyl hydroxylase 2 (HPH-2) was also demonstrated. Finally, we show that ING4 suppression in MM cells significantly increased vessel formation in vitro, blunted by blocking IL-8 or OPN. These in vitro observations were confirmed in vivo by finding that MM patients with high IL-8 production and microvascular density (MVD) have significantly lower ING4 levels compared with those with low IL-8 and MVD. Our data indicate that ING4 exerts an inhibitory effect on the production of proangiogenic molecules and consequently on MM-induced angiogenesis.

Abrogation of the interaction between osteopontin and αvβ3 integrin reduces tumor growth of human lung cancer cells in mice

Osteopontin (OPN) is a multifunctional cytokine involved in cell signaling by interacting with alphavbeta3 integrins. Recent clinical studies have indicated that OPN expression is associated with tumor progression and poor prognosis among patients with lung cancer. However, the biological role of OPN in human lung cancer has not yet been well-defined. The purpose of this study is to investigate and provide evidence for the causal role of OPN regarding tumor growth and angiogenesis in human lung cancer. In this study, we developed a stable OPN transfectant from human lung cancer cell line SBC-3 which does not express the intrinsic OPN mRNA. To reveal the in vivo effect of OPN on tumor growth of human lung cancer, we subcutaneously injected OPN-overexpressing SBC-3 cells (SBC-3/OPN) and control cells (SBC-3/NEO) into the nude mice. Transfection with the OPN gene significantly increased in vivo tumor growth and neovascularization of SBC-3 cells in mice. These in vivo effects of OPN were markedly suppressed with administration of anti-alphavbeta3 integrin monoclonal antibody or anti-angiogenic agent, TNP-470. Furthermore, recombinant OPN protein enhanced human umbilical vein endothelial cell (HUVEC) proliferation in vitro, and this enhancement was significantly inhibited with the addition of anti-alphavbeta3 integrin antibody. Taken together, these results suggest that OPN plays a crucial role for tumor growth and angiogenesis of human lung cancer cells in vivo by interacting with alphavbeta3 integrin. Targeting the interaction between OPN and alphavbeta3 integrin could be effective for future development of anti-angiogenic therapeutic agents for patients with lung cancer.

Elevated plasma osteopontin as marker for distant metastases and poor survival in patients with renal cell carcinoma

PURPOSE

To evaluate diagnostic and prognostic significance of plasma osteopontin (OPN) in patients with renal cell carcinoma (RCC).

METHODS

The retrospective study included 80 patients with RCC (pN0M0, n = 32; pN1M0, n = 11; M1, and n = 37), and 52 healthy controls (27 females and 25 males). OPN, the bone marker bone-specific alkaline phosphatase (bALP) and carboxyterminal telopetide of type-I collagen (ICTP), and the enzymes alanine aminotransferase (ALAT), and gamma-glutamyltransferase (GGT) were evaluated together with Memorial Sloan-Kettering Cancer Center (MSKCC) laboratory parameters. Data were analyzed by receiver-operating characteristics (ROC), survival analysis, and Cox proportional hazards regression model.

RESULTS

OPN and ICTP levels in RCC patients with distant metastases were significantly elevated (medians 115 and 4.7 microg/l, P < 0.001) compared to those without metastases (31.1 and 2.5 microg/l) and controls (28.9 and 2.1 microg/l) but did not differ between patients with bone or non-bone metastases. Both bALP and ALAT were not different between all study groups, while GGT was only increased in patients with non-bone metastases. In ROC analysis, OPN showed the best discrimination between patients with and without metastases (area under the curve: 0.888). High OPN values were associated with poor survival (Kaplan-Meier analysis, log-rank test, P = 0.002). Multivariate Cox regression with forward and backward stepwise elimination confirmed plasma OPN as independent predictive survival factor in RCC patients.

CONCLUSIONS

Our results show that high plasma OPN levels are associated with distant metastases and poor survival in RCC patients. The use of OPN as potential marker to monitor new treatment strategies in patients with advanced RCC should be evaluated in prospective studies.

Patched haploinsufficient mouse rhabdomyosarcoma overexpress secreted phosphoprotein 1 and matrix metalloproteinases

Rhabdomyosarcoma is the most common soft tissue sarcoma of childhood. Improving the management of rhabdomyosarcoma requires a better understanding of growth regulation. Patched haploinsufficient (Ptch+/-) mice spontaneously develop soft tissue sarcomas that resemble human rhabdomyosarcomas. Using microarray profiling and quantitative real-time reverse transcriptase polymerase chain reaction, we identified candidate genes differentially expressed in Ptch+/- mouse rhabdomyosarcoma relative to mature muscle. Overexpressed genes include Secreted Phosphoprotein 1 (Spp1, Osteopontin), and Matrix Metalloproteinases-2 and -14 (Mmp2 and Mmp14). Spp1 is an integrin-binding phosphoglycoprotein upregulated in carcinomas, and Mmps regulate tumour invasion. Immunochemical analyses of murine and human rhabdomyosarcoma specimens confirmed increased expression of Spp1, Mmp2, Mmp14, nuclear factor-kappa B (NF-kappaB) p65 and its phosphorylated active isoform. Neutralising Spp1 antibody decreased Mmp14 RNA in murine rhabdomyosarcoma cultures, indicating a positive regulatory role for extracellular Spp1. Plasma from rhabdomyosarcoma patients display elevated levels of SPP1. These results implicate Spp1, NF-kappaB, and Mmp activation as a putative signalling pathway involved in rhabdomyosarcoma growth.

Low dentin matrix protein 1 expression correlates with skeletal metastases development in breast cancer patients and enhances cell migratory capacity in vitro

Small integrin-binding ligand N-linked glycoproteins (SIBLINGs) constitute a family of extracellular matrix proteins involved in bone homeostasis. Their pattern of expression has been primarily reported in bone and tooth and, more recently, in several cancer types. Dentin matrix protein 1 (DMP1), a SIBLING family member, expression was investigated by immunohistochemistry in a retrospective series of 148 primary human breast cancers. Correlations between DMP1 expression levels in the tumors and clinicopathologic features, bone metastases development and relapse of the disease were examined. DMP1 was expressed by 63.5% of the breast tumors analyzed. Significant inverse associations were found between DMP1 expression levels and the size and grade of the tumors (both, P < 0.0001). High DMP1 expression levels in the primary breast lesions were associated with a lower risk of subsequent development of skeletal metastases (P = 0.009). Patients with tumors expressing high levels of DMP1 had a significantly higher disease-free survival rate than those with low DMP1-expressing tumors (P = 0.0062). When DMP1 expression was examined in breast cancer cell lines, we found that non invasive MCF-7 and T47-D cells expressed higher levels than highly invasive MDA-MB-231 and Hs578T cells. Moreover, the specific inhibition of DMP1 expression in MCF-7 cells using siRNAs promoted significantly their migratory capability. Our data implicate for the first time DMP1 expression in breast cancer progression and bone metastases development.

Osteopontin: a bridge between bone and blood

The production of mature blood cells within the bone marrow (BM) is attributed to a pool of haemopoietic stem cells (HSC). It is now evident that HSC reside preferentially at the endosteal region within the BM where bone-lining osteoblasts are a key cellular component of the HSC niche that directly regulates HSC fate. Osteoblasts synthesise proteins that stimulate and inhibit HSC proliferation. In addition to angiopoietin 1 (Ang-1), osteoblasts synthesise and express the highly acidic glycoprotein, osteopontin (Opn), which, like Ang-1, acts as a potent constraining factor on HSC proliferation. Overexpression of Opn is a feature of haemopoietic malignancies, such as multiple myeloma and chronic myeloid leukaemia, although its exact role in the aetiology and progression of these diseases remains unclear. Through osteoblasts and their cell surface and expressed proteins including Opn, bone is able to regulate the tissue that resides within it. In doing so, Opn can be considered a bridge between bone and blood.

Hypoxia in head and neck cancer

A high level of hypoxia in solid tumours is an adverse prognostic factor for the poor outcome of cancer patients following treatment. This review describes the status of research into finding a practical method for measuring hypoxia and treating hypoxic tumours. The application of such methodology would enable the selection of head and neck cancer treatment based on an individual's tumour oxygenation status. This individualization would include the selection not only of surgery or radiotherapy, but also of novel hypoxia-modification strategies.