Elevated osteopontin and thrombospondin expression identifies malignant human breast carcinoma but is not indicative of metastatic status

Long non-coding RNA miR155HG silencing restrains ovarian cancer progression by targeting the microRNA-155-5p/tyrosinase-related protein 1 axis

Ovarian cancer (OC) is the third commonest gynecological malignancy worldwide. The long non-coding (lnc)RNA microRNA (miR)155HG functions as an oncogene in different human cancers. However, the function and molecular mechanism of miR155HG in OC remain elusive. The present study indicated that the expression levels of miR155HG and tyrosinase-related protein 1 (TYRP1) were significantly increased, whereas that of miR155-5p was decreased in OC tissues and cells, as detected by real-time quantitative polymerase chain reaction. It was demonstrated that knockdown of miR155HG markedly inhibited OC cell viability, migration and invasion while promoting apoptosis, as indicated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, wound healing, Transwell and western blot assays. Mechanistically, it was revealed that miR155HG and TYRP1 were both targeted by miR-155-5p with complementary binding sites in the 3' untranslated region. A dual-luciferase reporter assay was used to confirm the targeting relationship between miR155HG, miR-155-5p and TYRP1. In addition, the interaction between miR155HG and miR-155-5p was further demonstrated by radioimmunoprecipitation and pull-down assays. In addition, feedback approaches determined that miR-155-5p inhibition or TYRP1 overexpression markedly reversed the inhibitory effects of miR155HG knockdown on OC cell viability, migration and invasion as well as weakened the promotive effect of miR155HG knockdown on OC cell apoptosis. Thus, miR155HG silencing inhibited the malignant biological behavior of OC cells by targeting the miR-155-5p/TYRP1 axis. The present study provides novel insights into the underlying mechanism of OC progression.

Establishment and Characterization of a Sclerosing Spindle Cell Rhabdomyosarcoma Cell Line with a Complex Genomic Profile

Sclerosing spindle cell rhabdomyosarcoma (SSRMS) is a rare rhabdomyosarcomas (RMS) subtype. Especially cases bearing a myogenic differentiation 1 (MYOD1) mutation are characterized by a high recurrence and metastasis rate, often leading to a fatal outcome. SSRMS cell lines are valuable in vitro models for studying disease mechanisms and for the preclinical evaluation of new therapeutic approaches. In this study, a cell line established from a primary SSRMS tumor of a 24-year-old female after multimodal chemotherapeutic pretreatment has been characterized in detail, including immunohistochemistry, growth characteristics, cytogenetic analysis, mutation analysis, evaluation of stem cell marker expression, differentiation potential, and tumorigenicity in mice. The cell line which was designated SRH exhibited a complex genomic profile, including several translocations and deletions. Array-comparative genomic hybridization (CGH) revealed an overall predominating loss of gene loci. The mesenchymal tumor origin was underlined by the expression of mesenchymal markers and potential to undergo adipogenic and osteogenic differentiation. Despite myogenic marker expression, terminal myogenic differentiation was inhibited, which might be elicited by the MYOD1 hotspot mutation. In vivo tumorigenicity could be confirmed after subcutaneous injection into NOD/SCID/γ_c^null mice. Summarized, the SRH cell line is the first adult SSRMS cell line available for preclinical research on this rare RMS subtype.

A targeted mass spectrometry immunoassay to quantify osteopontin in fresh-frozen breast tumors and adjacent normal breast tissues

Osteopontin (OPN) is a multifunctional protein that can activate cell-signaling pathways and lead to cancer development and metastasis. Elevated OPN expression was reported in different cancer types, including breast tumors. Here, we present a new immuno-mass spectrometry method for OPN quantification in fresh-frozen malignant and adjacent normal human breast tissues. For quantification we used two proteotypic peptides: OPN-peptide-1 and OPN-peptide-2. Peptide concentrations were determined by liquid chromatography-tandem mass spectrometry (LC-MS/MS) in multiple reaction monitoring (MRM) mode with stable isotope standards (SIS) and immuno-affinity enrichment for isolation of OPN peptides. Based on the OPN-peptide-1, the average OPN concentration in normal breast tissue was 19.42 μg/g, while the corresponding level in breast tumors was 603.9 μg/g. Based on OPN-peptide-2, the average concentration in normal breast tissue was 19.30 μg/g and in breast tumors 535.0 μg/g. In ER/PR/HER2(-) patients the OPN levels in breast tumors were significantly higher than in corresponding normal breast tissue samples, whereas in the single ER/PR/HER2(+) patient the OPN concentration in tumor samples was lower than in normal breast tissue sample. In conclusion, the current method is considered promising for the quantification of OPN in research and in clinical settings and should be further studied in breast cancer patients. SIGNIFICANCE: A new immuno-mass spectrometry method was successfully developed and applied to determine OPN concentrations in malignant tumor and normal breast tissues from six patients, and the method is promising for OPN quantification in both research and clinical settings.

The Differential Regulation of Human Telomerase Reverse Transcriptase and Vascular Endothelial Growth Factor May Contribute to the Clinically More Aggressive Behavior of P63-Positive Breast Carcinomas

p63, a p53 homologue, is a myoepithelial cell marker in the normal mammary gland but p63-positive neoplastic cells may be found in up to 11% of invasive breast carcinomas. This study aims to verify the relationship between p63 expression and several clinicopathological features and tumor markers of clinical significance in breast pathology including key regulators of the cell cycle, oncogenes, apoptosis-related proteins, metalloproteinases and their inhibitors. Immunohistochemistry with 27 primary antibodies was performed in 100 formalin-fixed paraffin-embedded samples of invasive ductal carcinomas. p63-positive cells were found in 16% of carcinomas. p63-positive carcinomas were poorly differentiated, hormone receptor-negative neoplasms with a high proliferation rate. p63 also correlated with advanced pathological stage, tumor size, and the expression of human telomerase reverse transcriptase (hTERT), tissue inhibitor of matrix metalloproteinase 1 (TIMP1) and vascular endothelial growth factor (VEGF). The expression of TIMP1 suggests that the anti-proteolytic stimuli may be preponderant in p63-positive carcinomas. hTERT activity is associated with nodal metastases and cellular proliferation. VEGF regulates angiogenesis, which is also a fundamental event in the process of tumor growth and metastatic dissemination. Thus, the differential regulation of hTERT and VEGF in p63-positive breast carcinomas may contribute to the clinically more aggressive behavior of these neoplasms.

Osteopontin Expression According to Molecular Profile of Invasive Breast Cancer: A Clinicopathological and Immunohistochemical Study

Osteopontin (OPN) is a secreted, calcium-binding phosphorylated glycoprotein involved in several physiological and pathological events such as angiogenesis, apoptosis, inflammation, wound healing, vascular remodeling, calcification of mineralized tissues, and induction of cell proteases. There is growing interest in the role of OPN in breast cancer. In an attempt to obtain new insight into the pathogenesis of OPN-associated breast carcinomas, an immunohistochemical panel with 17 primary antibodies including cytokeratins and key regulators of the cell cycle was performed in 100 formalin-fixed paraffin-embedded samples of invasive breast carcinomas. OPN was expressed in 65% of tumors and was negatively correlated with estrogen (p=0.0350) and progesterone (p=0.0069) receptors, but not with the other markers and clinicopathological features evaluated including age, menstrual status, pathological grading, tumor size, and metastasis. There was no correlation between OPN expression and carcinomas of the basal-like phenotype (p=0.1615); however, OPN correlated positively with c-erbB-2 status (p=0.0286) and negatively with carcinomas of the luminal subtype (p=0.0353). It is well known that carcinomas overexpressing c-erbB-2 protein have a worse prognosis than luminal tumors. Here, we hypothesize that the differential expression of OPN in the first subtype of carcinomas may contribute to their more aggressive behavior.

Anti-inflammatory properties of kaempferol via its inhibition of aldosterone signaling and aldosterone-induced gene expression

Osteopontin (OPN), also called cytokine Eta-1, is a pro-inflammatory cytokine. Recent studies have shown that aldosterone increases OPN gene expression in endothelial cells. As a flavonoid compound, kaempferol has potent anti-inflammatory properties, but whether kaempferol regulates aldosterone signaling and aldosterone-induced gene expression is still unknown. Human umbilical vein endothelial cells (HUVECs) were pretreated with kaempferol (0, 1, 3, or 10 μmol/L) for 1 h prior to exposure to aldosterone (10−6 mol/L) for 24 h. Aldosterone induced generation of reactive oxygen species; OPN and cluster of differentiation 44 gene expression; phospho-p38 MAPK and NF-κB binding activity. The effect of aldosterone was abrogated by kaempferol and spironolactone (10−6 mol/L). The present results suggest that kaempferol exerts its anti-inflammatory properties via its inhibition of aldosterone signaling and aldosterone-induced gene expression in HUVECs.

Correlation between TSP-1, TGF-β and PPAR-γ expression levels and glioma microvascular density

Gliomas are the most common type of primary tumor in the central nervous system and are characterized by abundant capillary angiogenesis. It is important to study the underlying molecular mechanisms of angiogenesis in order to aid the identification of potential therapeutic targets. The aim of the current study was to investigate the expression levels of thrombospondin-1 (TSP-1), transforming growth factor-β (TGF-β) and peroxisome proliferator-activated receptor-γ (PPAR-γ) in gliomas, and determine their relationships with angiogenesis. Immunohistochemical methods were used to detect TSP-1, TGF-β and PPAR-γ expression levels and to assess microvascular density (MVD) in 99 glioma tissue samples of various grades. The total positive expression rates of TSP-1 and PPAR-γ were 78.4 and 94.1% in low-grade gliomas and 45.8 and 39.6% in high-grade gliomas. These values suggest that their expression negatively correlated with tumor grade. However, TGF-β expression positively correlated with tumor grade; the total positive expression rate of TGF-β in high-grade gliomas (93.8%) was significantly increased compared with that in low-grade gliomas (43.1%). The MVD in the low-grade group was 28±7.2 vessels/field, which was significantly lower than in the high-grade group (45±6.2 vessels/field). TSP-1 and PPAR-γ expression levels were negatively correlated with MVD (P<0.05), while the TGF-β expression level was positively correlated with MVD (P<0.05). These results indicate that the TSP-1, TGF-β and PPAR-γ expression levels in gliomas are correlated with MVD, which suggests that these proteins may be involved in the regulation of glioma angiogenesis.

Thrombospondin-4 expression is activated during the stromal response to invasive breast cancer

The thromobospondins are a family of extracellular glycoproteins that are activated during tissue remodeling processes such as embryogenesis, wound healing and cancer. Thrombospondin-4 (THBS4) is known to have roles in cellular migration, adhesion and attachment, as well as proliferation in different contexts. Data to support a role in cancer biology is increasing, including for gastrointestinal and prostate tumours. Here, using a combination of immunohistochemistry, immunofluorescence and analysis of publicly available genomic and expression data, we present the first study describing the pattern of expression of THBS4 in normal breast and breast cancer. THBS4 was located to the basement membrane of large ducts and vessels in normal breast tissue, but was absent from epithelium and extracellular matrix. There was a significant induction in expression in cancer-associated stroma relative to normal stroma (P = 0.0033), neoplastic epithelium (P < 0.0001) and normal epithelium (P < 0.0001). There was no difference in stromal expression of THBS4 between invasive ductal carcinomas (IDC) and invasive lobular carcinomas (ILC). The THBS4 mRNA levels were variable yet were generally highest in tumours typically rich in stromal content (ILC, ER positive low grade IDC; luminal A and normal-like subtypes). Genomic alterations of the THBS4 gene (somatic mutations and gene copy number) are rare suggesting this dramatic activation in expression is most likely dynamically regulated through the interaction between invading tumour cells and stromal fibroblasts in the local microenvironment. In summary, THBS4 expression in breast cancer-associated extracellular matrix contributes to the activated stromal response exhibited during tumour progression and this may facilitate invasion of tumour cells.

Risk assessment, disease prevention and personalised treatments in breast cancer: is clinically qualified integrative approach in the horizon?

Breast cancer is a multifactorial disease. A spectrum of internal and external factors contributes to the disease promotion such as a genetic predisposition, chronic inflammatory processes, exposure to toxic compounds, abundant stress factors, a shift-worker job, etc. The cumulative effects lead to high incidence of breast cancer in populations worldwide. Breast cancer in the USA is currently registered with the highest incidence rates amongst all cancer related patient cohorts. Currently applied diagnostic approaches are frequently unable to recognise early stages in tumour development that impairs individual outcomes. Early diagnosis has been demonstrated to be highly beneficial for significantly enhanced therapy efficacy and possibly full recovery. Actual paper shows that the elaboration of an integrative diagnostic approach combining several levels of examinations creates a robust platform for the reliable risk assessment, targeted preventive measures and more effective treatments tailored to the person in the overall task of breast cancer management. The levels of examinations are proposed, and innovative technological approaches are described in the paper. The absolute necessity to create individual patient profiles and extended medical records is justified for the utilising by routine medical services. Expert recommendations are provided to promote further developments in the field.

Transcriptomic comparison of osteopontin, osteocalcin and core binding factor 1 genes between human adipose derived differentiated osteoblasts and native osteoblasts

BACKGROUND

There are significant limitations in repair of irrecoverable bone defects. Stem-cell therapy is a promising approach for the construction of bone tissue. Mesenchymal stem cells (MSCs) have been introduced as basic tools for bone tissue generation. Through MSCs, adipose-derived stem cells (ADSCs) are more interesting. Since the similarity of native osteoblasts and differentiated osteoblasts from ADSCs in terms of gene expression pattern is unknown, this study was designed to compare gene expression patterns of some genes involved in osteogenesis between human native osteoblasts and adipose-derived differentiated osteoblasts.

MATERIALS AND METHODS

Realtime qRT-PCR was used for studying the gene expression of osteocalcin, osteopontin, and core binding factor alpha 1 (Cbfa1) in human native osteoblasts and adipose derived osteogenic osteoblasts at days 7, 14, 21, and 28 of differentiation.

RESULTS

This study demonstrated that native osteoblasts and differentiated osteoblasts, cultured in common osteogenic medium, have significant differences in gene expression levels for osteocalcin and osteopontin. Compared to native osteoblasts, these genes are expressed lower in all four groups of differentiated osteoblastic cells. We also found, there is a progressive increase in cbfa1 expression over the differentiation period of ADSCs from day 7 to day 28.

CONCLUSIONS

Our findings help for better assessment of adipose-derived differentiated cells as a source for cell-based therapy.

sFRP-1 binds via its netrin-related motif to the N-module of thrombospondin-1 and blocks thrombospondin-1 stimulation of MDA-MB-231 breast carcinoma cell adhesion and migration

Secreted frizzled-related protein (sFRP)-1 is a Wnt antagonist that inhibits breast carcinoma cell motility, whereas the secreted glycoprotein thrombospondin-1 stimulates adhesion and motility of the same cells. We examined whether thrombospondin-1 and sFRP-1 interact directly or indirectly to modulate cell behavior. Thrombospondin-1 bound sFRP-1 with an apparent K(d)=48nM and the related sFRP-2 with a K(d)=95nM. Thrombospondin-1 did not bind to the more distantly related sFRP-3. The association of thrombospondin-1 and sFRP-1 is primarily mediated by the amino-terminal N-module of thrombospondin-1 and the netrin domain of sFRP-1. sFRP-1 inhibited α3β1 integrin-mediated adhesion of MDA-MB-231 breast carcinoma cells to a surface coated with thrombospondin-1 or recombinant N-module, but not adhesion of the cells on immobilized fibronectin or type I collagen. sFRP-1 also inhibited thrombospondin-1-mediated migration of MDA-MB-231 and MDA-MB-468 breast carcinoma cells. Although sFRP-2 binds similarly to thrombospondin-1, it did not inhibit thrombospondin-1-stimulated adhesion. Thus, sFRP-1 binds to thrombospondin-1 and antagonizes stimulatory effects of thrombospondin-1 on breast carcinoma cell adhesion and motility. These results demonstrate that sFRP-1 can modulate breast cancer cell responses by interacting with thrombospondin-1 in addition to its known effects on Wnt signaling.

Angiogenesis in chronic liver disease and its complications

Nowadays, liver cancer, cirrhosis and other liver-related diseases are the fifth most common cause of mortality in the UK. Furthermore, chronic liver diseases (CLDs) are one of the major causes of death, which are still increasing year-on-year. Therefore, knowledge about the pathophysiology of CLDs and its complications is of uttermost importance. The goal of this review is to clarify the role of angiogenesis in the disease progression of various liver diseases. Looking closer at the pathophysiology of portal hypertension (PH), fibrosis, cirrhosis, non-alcoholic steatohepatitis (NASH) and hepatocellular carcinoma (HCC), we find that angiogenesis is a recurring factor in the disease progression. In PH, several factors involved in its pathogenesis, such as hypoxia, oxidative stress, inflammation and shear stress are potential mediators for the angiogenic response. The progression from fibrosis to cirrhosis, the end-point of CLDs, is distinguished by a prolonged inflammatory and fibrogenic process that leads to an abnormal angioarchitecture distinctive for cirrhosis. In several stages of NASH, a link might be made between the disease progression and hepatic microvasculature changes. HCC is one of the most vascular solid tumours in which angiogenesis plays an important role in its development, progression and metastasis. The close relationship between the progression of CLDs and angiogenesis emphasises the need for anti-angiogenic therapy as a tool for blocking or slowing down the disease progression. The fact that angiogenesis plays a pivotal role in CLDs gives rise to new opportunities for treating CLDs and its complications.

Role of the metastasis-promoting protein osteopontin in the tumour microenvironment

Osteopontin (OPN) is a secreted protein present in bodily fluids and tissues. It is subject to multiple post-translational modifications, including phosphorylation, glycosylation, proteolytic cleavage and crosslinking by transglutamination. Binding of OPN to integrin and CD44 receptors regulates signalling cascades that affect processes such as adhesion, migration, invasion, chemotaxis and cell survival. A variety of cells and tissues express OPN, including bone, vasculature, kidney, inflammatory cells and numerous secretory epithelia. Normal physiological roles include regulation of immune functions, vascular remodelling, wound repair and developmental processes. OPN also is expressed in many cancers, and elevated levels in patients’ tumour tissue and blood are associated with poor prognosis. Tumour growth is regulated by interactions between tumour cells and their tissue microenvironment. Within a tumour mass, OPN can be expressed by both tumour cells and cellular components of the tumour microenvironment, and both tumour and normal cells may have receptors able to bind to OPN. OPN can also be found as a component of the extracellular matrix. The functional roles of OPN in a tumour are thus complex, with OPN secreted by both tumour cells and cells in the tumour microenvironment, both of which can in turn respond to OPN. Much remains to be learned about the cross-talk between normal and tumour cells within a tumour, and the role of multiple forms of OPN in these interactions. Understanding OPN-mediated interactions within a tumour will be important for the development of therapeutic strategies to target OPN.

Estrogen regulation of thrombospondin-1 in human breast cancer cells

Expression of thrombospondin-1 (TSP-1), a large extracellular matrix protein, has been associated with modulation of angiogenesis and tumor growth. Both pro and antiangiogenic properties of TSP-1 have been described, and the role of TSP-1 expression in the growth and progression of human breast cancer is not clear. Because estrogens cause progression of many breast cancers, and estradiol (E2) downregulates a TSP-1 receptor, we examined whether TSP-1 is regulated by estrogen and involved in tumor progression. E2 induced TSP-1 expression in T47-D and MCF-7 breast cancer cells in vitro within 3 to 6 hr; the induction was blocked by the anti-estrogen ICI 182,780, indicating that estrogen receptors (ER) are necessary for this effect. Furthermore, E2 caused the production of TSP-1 protein from tumor cells in an ER-alpha-dependent manner. The E2-mediated TSP-1 RNA induction was dose-dependent and blocked by actinomycin D, indicating that the response to E2 was at least partly transcriptional. Transfection studies with deletion constructs of the TSP-1 promoter identified an estrogen-responsive region in the human TSP-1 promoter, located between -2,200 and -1,792 bp upstream of the transcription start site. An antibody against TSP-1 restricted the proliferation of E2-dependent MCF-7 cells in vitro and in vivo. A panel of breast cancer cells proliferated in the presence of low concentrations of exogenous TSP-1, whereas higher concentrations inhibited proliferation. A real-time PCR analysis showed that E2 also induced TSP-1 mRNA in the normal mammary glands of immature ovariectomized mice in an ER-dependent manner. In summary, we report the novel observation that TSP-1 production is directly controlled by estrogens in ER-positive breast cancer cells, and the released protein has pro-growth regulatory functions. Consequently, we propose that TSP-1 could be a therapeutic target for anti-tumor therapy in early-stage tumors. (c) 2009 UICC.

Distinct gene-expression profiles characterize mammary tumors developed in transgenic mice expressing constitutively active and C-terminally truncated variants of STAT5

Background

Stat5 is a latent transcription factor that regulates essential growth and survival functions in normal cells. Constitutive activity of Stat5 and the involvement of its C-terminally truncated variant have been implicated in blood cell malignancies and mammary or breast cancer. To distinguish the individual contributions of the Stat5 variants to mammary tumorigenesis, global gene-expression profiling was performed on transgenic STAT5-induced tumors.

Results

We identified 364 genes exhibiting differential expression in mammary tumors developed in transgenic mice expressing constitutively active STAT5 (STAT5ca) vs. its C-terminally truncated variant (STAT5Δ750). These genes mediate established Stat5 effects on cellular processes such as proliferation and cell death, as well as yet-unrelated homeostatic features, e.g. carbohydrate metabolism. A set of 14 genes linked STAT5Δ750 expression to the poorly differentiated carcinoma phenotype and STAT5ca to the highly differentiated papillary adenocarcinoma.

Specifically affected genes exhibited differential expression in an individual tumor set vs. its counterpart and the intact mammary gland: 50 genes were specifically affected by STAT5ca, and 94% of these were downregulated, the latter involved in suppression of tumor suppressors and proliferation antagonistics. This substantial downregulation distinguishes the STAT5ca-induced tumorigenic consequences from the relatively equal effect of the STAT5Δ750 on gene expression, which included significant elevation in the expression of oncogenes and growth mediators.

STAT5Δ750 mRNA expression was below detection levels in the tumors and the amount of STAT5ca transcript was not correlated with the expression of its specifically affected genes. Interestingly, we identified several groups of three to eight genes affected by a particular STAT5 variant with significant correlated expression at distinct locations in the clustergram.

Conclusion

The different gene-expression profiles in mammary tumors caused by the STAT5Δ750 and STAT5ca variants, corroborated by the absence of a direct link to transgenic STAT5 expression, imply distinct metabolic consequences for their oncogenic role which probably initiate early in tumor development. Tumorigenesis may involve induction of growth factor and oncogenes by STAT5Δ750 or suppression of tumor suppressors and growth antagonists by STAT5ca. The list of genes specifically affected by the STAT5 variants may provide a basis for the development of a marker set for their distinct oncogenic role.

Thrombospondin 1 expression and angiogenesis in breast carcinoma and their relation with platelet activity

This study investigates angiogenesis and the expression of thrombospondin 1 in invasive ductal carcinoma of the breast and their possible relation to platelet counts and platelet activity. The study included 20 cases of invasive ductal carcinoma. Platelet activity was evaluated by determining thromboxane B2 and cyclic guanosine monophosphate (cGMP) levels by enzyme immunoassay (EIA).Thrombospondin (TSP) 1 and CD34 expression was studied immunohistochemically. Mean platelet count of the patient group was significantly greater than the mean platelet count of the control group (P < 0.05). The platelet counts were positively correlated with tumour size (r=0.609; P < 0.01). Platelet counts were higher in the patients who had grade 3 microvessel density (P < 0.05). The mean basal platelet cGMP level in the patient group was significantly lower than it was in the control group (P < 0.05). Focal TSP immunoreactivity was detectable in 5 (20%) cases in the tumour cells, and in 9 (45%) cases in the stroma. We did not find any correlation between TSP-1 staining and angiogenesis, platelet counts, platelet activity, and the histological prognostic parameters. Our study confirms the essential role of platelets in tumour growth and angiogenesis. Decreased levels of cGMP in the patient group may cause platelet hyperreactivity. Although thrombospondin 1 may be upregulated in malignant breast tissue, this is not sufficient for tumour growth and dissemination according to our results.

Breast tumor metastasis: analysis via proteomic profiling

The ability to predict the metastatic behavior of a patient's cancer, as well as to detect and eradicate such recurrences, remain major clinical challenges in oncology. While many potential molecular biomarkers have been identified and tested previously, none have greatly improved the accuracy of specimen evaluation over routine histopathological criteria and, to date, they predict individual outcomes poorly. The ongoing development of high-throughput proteomic profiling technologies is opening new avenues for the investigation of cancer and, through application in tissue-based studies and animal models, will facilitate the identification of molecular signatures that are associated with breast tumor cell phenotype. The appropriate use of these approaches has the potential to provide efficient biomarkers, and to improve our knowledge of tumor biology. This, in turn, will enable the development of targeted therapeutics aimed at ameliorating the lethal dissemination of breast cancer. In this review, we focus on the accumulating proteomic signatures of breast tumor progression, particularly those that correlate with the occurrence of distant metastases, and discuss some of the expected future developments in the field.

Thrombospondins in cancer

The thrombospondins (TSPs) are a family of five proteins that are involved in the tissue remodeling that is associated with embryonic development, wound healing, synaptogenesis, and neoplasia. These proteins mediate the interaction of normal and neoplastic cells with the extracellular matrix and surrounding tissue. In the tumor microenvironment, TSP-1 has been shown to suppress tumor growth by inhibiting angiogenesis and by activating transforming growth factor beta. TSP-1 inhibits angiogenesis through direct effects on endothelial cell migration and survival, and through effects on vascular endothelial cell growth factor bioavailability. In addition, TSP-1 may affect tumor cell function through interaction with cell surface receptors and regulation of extracellular proteases. Whereas the role of TSP-1 in the tumor microenvironment is the best characterized, the other TSPs may have similar functions. (Part of a Multi-author Review).

Genomic signatures of breast cancer metastasis

Despite significant advances in the treatment of primary cancer, the ability to predict the metastatic behavior of a patient's cancer, as well as to detect and eradicate such recurrences, remain major clinical challenges in oncology. While many potential molecular biomarkers have been identified and tested previously, none have greatly improved the accuracy of specimen evaluation over routine histopathological criteria and they predict individual outcomes poorly. However, the recent introduction of high-throughput microarray technology has opened new avenues in genomic investigation of cancer, and through application in tissue-based studies and appropriate animal models, has facilitated the identification of gene expression signatures that are associated with the lethal progression of breast cancer. The use of these approaches has the potential to greatly impact our knowledge of tumor biology, to provide efficient biomarkers, and enable development towards customized prognostication and therapies for the individual.

Atorvastatin affects several angiogenic mediators in human endothelial cells

The pleiotropic effects of statins, inhibitors of 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase, have been recently extended to the modulation of angiogenesis. Here, to get more insight into the statins action, the authors have investigated the effect of atorvastatin on the expression of several angiogenic and inflammatory genes in human umbilical endothelial cells (HUVECs). Atorvastatin was proangiogenic at the dose of 10 nM, and antiangiogenic at the concentrations of 1 to 10 micro M. Moreover, these higher concentrations inhibited also the proliferation of HUVECs induced by vascular endothelial growth factor (VEGF). Lower doses of atorvastatin did not influence endothelial cell proliferation. Importantly, atorvastatin at the micromolar concentrations diminished the production of interleukin (IL)-8, a proinflammatory and proangiogenic chemokine, and inhibited the synthesis of urokinase plasminogen activator (uPA), a potent proinflammatory mediator. However, it decreased also the expression of plasminogen activator inhibitor-1 (PAI-1) and thrombospondin-1 (TSP-1), the inhibitors of angiogenesis. Atorvastatin stimulated the expression of angiopoietin (Ang)-2 and moderately enhanced the expression of endothelial nitric oxide synthase (eNOS), whereas heme oxygenase-1 (HO-1) was not significantly affected. In conclusion, the present findings points to other angiogenesis-related effects of atorvastatin, which may be of relevance to the beneficial influence of statins in cardiovascular system.

Characterisation of two rat mammary tumour models for breast cancer research by gene expression profiling

Breast cancer is the most frequently occurring cancer in women. Treatment options are still an active area of research. Models used for this purpose include induced models in rodents. By the advent of microarrays it has become possible to evaluate models not only for similar morphology or selected markers by polymerase chain reaction (PCR) or immunohistochemistry but also for the expression of thousands of genes at once. This study presents gene expression profiles of the hormone-sensitive 7,12-dimethylbenzanthracene-induced and the metastasising MTLn3-model. The models are discussed for their relevance to breast cancer in humans.

Androgen and fibroblast growth factor 8 (FGF8) downregulation of thrombospondin 1 (TSP1) in mouse breast cancer cells

In the search for androgen target genes responsible for malignant growth in S115 mouse mammary tumor cells we found that thrombospondin 1 (TSP1) expression was strongly downregulated by testosterone (Te). Experiments with cycloheximide suggested that Te repression of TSP1 was dependent on de novo protein synthesis. TSP1 repression by Te was preceded by the induction of fibroblast growth factor 8 (FGF8) expression. FGF8 has previously been shown to mediate androgen effects on proliferation of S115 cells by autocrine/paracrine mechanisms. It has also been shown to increase breast cancer cell growth as tumors in nude mice and to stimulate tumor angiogenesis. We studied here the possibility that FGF8 belonged to the Te-induced de novo synthesized proteins that mediate the effect of Te on TSP1 expression in these cells. We found that addition of FGF8b to in vitro cultures or ectopic expression of FGF8b in S115 cells repressed TSP1 expression at mRNA and protein levels even in the absence of Te. FGF2, another angiogenic member of FGF family, also downregulated TSP1 mRNA level in the in vitro cultures of S115 cells. The antisense oligonucleotides for FGF8 did not, however, prevent Te-repression of TSP1 mRNA expression and a neutralizing anti-FGF8b antibody only partially opposed Te induced downregulation of TSP1. These results suggest that both androgen and FGF8 inhibit TSP1 expression independently. They also suggest that opposite to many other androgen-induced responses in S115 cells, the effect of Te on the expression TSP1 is not mediated by FGF8.

Roles of MAP kinases in the regulation of bone matrix gene expressions in human osteoblasts by oscillatory fluid flow

We investigated the effects of oscillatory flow in regulating the gene expressions of type I collagen (COL1, the main component of human bone tissues) and osteopontin (OPN, the key gene for calcium deposition) in human osteoblast-like (MG-63) cells, and the roles of mitogen-activated protein kinases (MAPKs) in this regulation. The cells were subjected to oscillatory flow (0.5 +/- 4 dyn/cm(2)) or kept under static condition for various time periods (15 min, 30 min, 1 h, 2 h, 4 h, 8 h, and 16 h). Oscillatory flow caused significant up-regulations of both COL1 and OPN gene expressions over the 16 h of study, and a transient activation of MAPKs was starting at 15 min and declining to basal level in 2 h. The flow-induction of COL1 was blocked by an ERK inhibitor (PD98059) and reduced by a JNK inhibitor (SP600125), whereas that of OPN was abolished by PD98059. Analysis of the cis-elements in the COL1 and OPN promoters suggests the involvement of transacting factors Elk-1 and AP-1 in the transcription regulation. The ERK inhibitor (PD98059) blocked Elk-1 phosphorylation, as well as COL1 and OPN gene expression. The JNK inhibitor (SP600125) abolished c-jun phosphorylation and COL1 expression. These results suggest that the flow-induction of OPN was mediated through the ERK-Elk1-OPN pathway, and that COL1 was regulated by both the ERK-Elk1-COL1 and JNK-c-JUN-COL1 pathway.

Osteopontin expression correlates with prognostic variables and survival in clear cell renal cell carcinoma

BACKGROUND AND OBJECTIVES

Osteopontin (OPN) is a phosphorylated glycoprotein with diverse functions including tumorigenesis and tumor cell metastasis. Recently, it has been detected in a growing number of human tumors, and assessed as a potential prognostic marker. The aim of this study was to analyze the expression of OPN in normal renal tissue and clear cell renal cell carcinomas (CRCCs), and to assess its prognostic significance.

METHODS

The expression of OPN protein was immunohistochemically analyzed in 171 CRCCs and compared to usual clinicopathological parameters such as tumor size, nuclear grade, pathological stage, Ki-67 proliferation index, and cancer-specific survival.

RESULTS

In normal renal parenchyma, the expression of OPN was seen in distal tubular epithelial cells, calcifications, and some stromal cells. The upregulation of OPN was observed in 61 CRCCs (35.7%) in the form of cytoplasmic granular staining of various intensities. Statistical analysis showed correlation of the OPN expression with tumor size (P < 0.001), Fuhrman nuclear grade (P < 0.001), pathological stage (P = 0.011), and Ki-67 proliferation index (P < 0.001). Moreover, patients with OPN-positive tumors had significantly worse prognosis in comparison to patients with tumors lacking OPN protein (P = 0.004).

CONCLUSION

Our results suggest that overexpression of OPN is involved in the progression of CRCC.

Immunohistochemical expression of thrombospondin-1 in invasive vulvar squamous cell carcinoma

OBJECTIVES

Thrombospondin-1 (TSP-1) is a multifunctional matricellular glycoprotein involved in several mechanisms critical to the formation and progression of solid tumors including cell adhesion, proliferation, migration, invasion, and angiogenesis. The present study was designed to investigate the expression of TSP-1 in invasive vulvar squamous cell carcinoma.

METHODS

A total of 75 invasive vulvar squamous cell carcinomas were evaluated for TSP-1 expression by immunohistochemistry. Results were correlated with the clinicopathologic parameters including tumor stage, groin lymph node status, tumor grade, patient's age, patients' disease-free, and overall survival.

RESULTS

TSP-1 expression was detected in 35/75 (46.7%) specimens of invasive vulvar squamous cell carcinomas. The expression of TSP-1 was generally localized to the cytoplasm and occasionally seen in the nucleus. An increased TSP-1 expression was detected in patients with an advanced tumor stage (P = 0.01) and a positive groin lymph nodes status (P = 0.01). Tumor stage and groin lymph node status were associated with patients' disease-free and overall survival. All other parameters failed to be of prognostic significance.

CONCLUSIONS

We are the first to report on the immunohistochemical expression of TSP-1 in invasive vulvar squamous cell carcinoma. Increased TSP-1 expression was associated with an advanced tumor stage and a positive groin lymph node status, suggesting its pro-angiogenic potential in vulvar carcinogenesis.

The RhoGAP protein DLC-1 functions as a metastasis suppressor in breast cancer cells

The identification of molecular signatures characteristic of tumor cells that are capable of metastatic spread is required for the development of therapeutic interventions to abrogate this lethal process. To facilitate this, we have previously characterized an experimental system in which the role of candidate metastasis-related genes can be screened and tested. Monoclonal cell lines M4A4 and NM2C5 are spontaneously occurring sublines of the MDA-MB-435 cell breast tumor cell line that exhibit phenotypic differences in growth, invasion, and metastatic efficiency in athymic mice. In this study, transcriptional profiles of these cell lines were created using oligonucleotide microarrays representing over 12,000 genes. Intensity modeling and hierarchical clustering analysis identified a 171-gene expression signature that correlated with metastatic phenotype and highlighted several GTPase signaling components. Restoration of one of these GTPases, deleted in liver cancer-1 (DLC-1), in metastatic M4A4 cells to levels observed in the nonmetastatic NM2C5 cell line resulted in the inhibition of migration and invasion in vitro and a significant reduction in the ability of these cells to form pulmonary metastases in athymic mice. These studies show the utility of expression profiling, in an appropriate experimental system, to identify genetic determinants of metastatic sufficiency. The finding that DLC-1 can act as a metastasis-suppressor gene supports an influential role for GTPase signaling in tumor progression.

Osteopontin expression correlates with melanoma invasion

Melanoma is one of the most aggressive cancers affecting humans. Although early melanomas are curable with surgical excision, metastatic melanomas are associated with high mortality. The mechanism of melanoma development, progression, and metastasis is largely unknown. In order to uncover genes unique to melanoma cells, we used high-density DNA microarrays to examine the gene expression profiles of metastatic melanoma nodules using benign nevi as controls. Over 190 genes were significantly overexpressed in metastatic melanomas compared with normal nevi by at least 2-fold. One of the most abundantly expressed genes in metastatic melanoma nodules is osteopontin (OPN). Immunohistochemistry staining on tissue microarrays and individual skin biopsies representing different stages of melanoma progression revealed that OPN expression is first acquired at the step of melanoma tissue invasion. In addition, blocking of OPN expression by RNA interference reduced melanoma cell numbers in vitro. Our observations suggest that OPN may be acquired early in melanoma development and progression, and may enhance tumor cell growth in invasive melanoma.

Expression of Receptor Activator of Nuclear Factor-κB Ligand Is Inversely Correlated with Metastatic Phenotype in Breast Carcinoma

During normal bone remodeling, the receptor activator of nuclear factor-κB (RANK) interacts with its ligand RANKL, which is present on pre-osteoclasts, resulting in bone resorption and initiation of new bone formation. When breast cancer metastasizes to bone, normal bone remodeling is disturbed by invasion of tumor cells, resulting in osteolytic lesions. We have studied the expression of both RANK and RANKL in 10 nonneoplastic breast samples, 58 infiltrating ductal carcinoma (IDC), and 43 breast cancer bony metastases (BTM). RANK seemed to be present in all samples tested. However, whereas RANKL expression was observed in 90% of nonneoplastic breast, RANKL expression was only observed in 62% of nonmetastatic IDC, 31% of metastatic IDC, and 2% of osteolytic BTM lesions. This decreased or absent expression of RANKL in the tumor cells may allow RANK, which is normally expressed as a receptor on the cell surface, to target RANKL present on the cell surface of normal osteoblasts and stromal cells of the bone. Stimulation of the normal osteoblasts and stromal cells by the tumor cells may then lead to secondary osteoclastogenesis, resulting in the osteolytic phenotype common to breast metastases.

Role of osteopontin in tumour progression

Since its first identification as a transformation-associated protein, osteopontin (OPN) has been recognised as important in the processes of tumorigenicity and metastasis. Here, we review the evidence that OPN might be considered as a candidate prognostic marker in human cancer. In animal systems, evidence from cell injection experiments and genetically manipulated mice suggest an important but complex role for the protein in tumour progression. Moreover, studies in a variety of human cancers associate high levels of OPN expression in tumours or in blood with more advanced cancers. The mechanism of action of OPN in promoting cancer is still unclear, and we consider aspects of OPN biology that can complicate interpretation of human studies. Nevertheless, growing evidence supports a role for OPN as a potential prognostic factor for various human cancers.

Molecular analysis of metastasis in a polyomavirus middle T mouse model: the role of osteopontin

INTRODUCTION

In order to study metastatic disease, we employed the use of two related polyomavirus middle T transgenic mouse tumor transplant models of mammary carcinoma (termed Met and Db) that display significant differences in metastatic potential.

METHODS

Through suppression subtractive hybridization coupled to the microarray, we found osteopontin (OPN) to be a highly expressed gene in the tumors of the metastatic mouse model, and a lowly expressed gene in the tumors of the lowly metastatic mouse model. We further analyzed the role of OPN in this model by examining sense and antisense constructs using in vitro and in vivo methods.

RESULTS

With in vivo metastasis assays, the antisense Met cells showed no metastatic tumor formation to the lungs of recipient mice, while wild-type Met cells, with higher levels of OPN, showed significant amounts of metastasis. The Db cells showed a significantly reduced metastasis rate in the in vivo metastasis assay as compared with the Met cells. Db cells with enforced overexpression of OPN showed elevated levels of OPN but did not demonstrate an increase in the rate of metastasis compared with the wild-type Db cells.

CONCLUSIONS

We conclude that OPN is an essential regulator of the metastatic phenotype seen in polyomavirus middle T-induced mammary tumors. Yet OPN expression alone is not sufficient to cause metastasis. These data suggest a link between metastasis and phosphatidylinositol-3-kinase-mediated transcriptional upregulation of OPN, but additional phosphatidylinositol-3-kinase-regulated genes may be essential in precipitating the metastasis phenotype in the polyomavirus middle T model.

The interrelationship between DRIM gene expression and cytogenetic and phenotypic characteristics in human breast tumor cell lines

Background

In order to facilitate the identification of genes involved in the metastatic phenotype we have previously developed a pair of cell lines from the human breast carcinoma cell line MDA-MB-435, which have diametrically opposite metastatic potential in athymic mice. Differential display analysis of this model previously identified a novel gene, DRIM (down regulated in metastasis), the decreased expression of which correlated with metastatic capability. DRIM encodes a protein comprising 2785 amino acids with significant homology to a protein in yeast and C. elegans, but little else is currently known about its function or pattern of expression. In a detailed analysis of the DRIM gene locus we quantitatively evaluated gene dosage and the expression of DRIM transcripts in a panel of breast cell lines of known metastatic phenotype.

Results

Fluorescent in situ hybridization (FISH) analyses mapped a single DRIM gene locus to human chromosome 12q23~24, a region of conserved synteny to mouse chromosome 10. We confirmed higher expression of DRIM mRNA in the non-metastatic MDA-MB-435 clone NM2C5, relative to its metastatic counterpart M4A4, but this appeared to be due to the presence of an extra copy of the DRIM gene in the cell line's genome. The other non-metastatic cell lines in the series (T47D MCF-7, SK-BR-3 and ZR-75-1) contained either 3 or 4 chromosomal copies of DRIM gene. However, the expression level of DRIM mRNA in M4A4 was found to be 2–4 fold higher than in unrelated breast cells of non-metastatic phenotype.

Conclusions

Whilst DRIM expression is decreased in metastatic M4A4 cells relative to its non-metastatic isogenic counterpart, neither DRIM gene dosage nor DRIM mRNA levels correlated with metastatic propensity in a series of human breast tumor cell lines examined. Collectively, these findings indicate that the expression pattern of the DRIM gene in relation to the pathogenesis of breast tumor metastasis is more complex than previously recognized.