Role of osteopontin in breast cancer patients

Modulation of the tumor microenvironment by natural agents: implications for cancer prevention and therapy

The development of cancer is not just the growth and proliferation of a single transformed cell, but its surrounding environment also coevolves with it. Indeed, successful cancer progression depends on the ability of the tumor cells to develop a supportive tumor microenvironment consisting of various types of stromal cells. The interactions between the tumor and stromal cells are bidirectional and mediated through a variety of growth factors, cytokines, metabolites, and other biomolecules secreted by these cells. Tumor-stromal crosstalk creates optimal conditions for the tumor growth, metastasis, evasion of immune surveillance, and therapy resistance, and its targeting is being explored for clinical management of cancer. Natural agents from plants and marine life have been at the forefront of traditional medicine. Numerous epidemiological studies have reported the health benefits imparted on the consumption of certain fruits, vegetables, and their derived products. Indeed, a significant majority of anti-cancer drugs in clinical use are either naturally occurring compounds or their derivatives. In this review, we describe fundamental cellular and non-cellular components of the tumor microenvironment and discuss the significance of natural compounds in their targeting. Existing literature provides hope that novel prevention and therapeutic approaches will emerge from ongoing scientific efforts leading to the reduced tumor burden and improve clinical outcomes in cancer patients.

An interaction network approach to study the correlation between endocrine disrupting chemicals and breast cancer

Endocrine disrupting chemicals (EDCs) are natural or synthetic exogenous substances affecting human health. Although present at low concentrations in the environment, they can cause a broad range of negative effects on the endocrine functions by mimicking the action of steroid hormones due to their structural similarity. Hormonal unbalance can play an important role in carcinogenesis at any stage of disease. In the case of the breast cancer, EDCs directly affect the transformation of normal breast cells into cancer cells by interfering with hormonal regulation and by inducing the alteration of factors that regulate gene expression. The principal aims of this work were to study the interaction networks of proteins modulated in breast cancer by either environmental EDCs or mycotoxins, and to identify the proteins with the strongest coordination role defined as hub nodes. Our studies evidenced the presence of seven and six hub proteins in two EDCs and mycotoxins networks, respectively. Then, by merging the two networks, we identified that three hub nodes (BCL2, ESR2 and CTNNB1) in the environmental EDCs network show direct interactions with three hub nodes (CASP8, RELA and MKI67) in the mycotoxins network. These data highlighted that two networks are linked through proteins involved in the apoptosis regulation and in processes related to cell proliferation and survival, and, thus, in breast cancer progression.

Electrochemical aptasensor for human osteopontin detection using a DNA aptamer selected by SELEX

A DNA aptamer with affinity and specificity for human osteopontin (OPN), a potential breast cancer biomarker, was selected using the SELEX process, considering its homology rate and the stability of its secondary structures. This aptamer exhibited a satisfactory affinity towards OPN, showing dissociation constants lower than 2.5 nM. It was further used to develop a simple, label-free electrochemical aptasensor against OPN. The aptasensor showed good sensitivity towards OPN in standard solutions, being the square wave voltammetry (SWV), compared to the cyclic voltammetry, the most sensitive technique with detection and quantification limits of 1.4 ± 0.4 nM and 4.2 ± 1.1 nM, respectively. It showed good reproducibility and acceptable selectivity, exhibiting low signal interferences from other proteins, as thrombin, with 2.6-10 times lower current signals-off than for OPN. The aptasensor also successfully detected OPN in spiked synthetic human plasma. Using SWV, detection and quantification limits (1.3 ± 0.1 and 3.9 ± 0.4 nM) within the OPN plasma levels reported for patients with breast cancer (0.4-4.5 nM) or with metastatic or recurrent breast cancer (0.9-8.4 nM) were found. Moreover, preliminary assays, using a sample of human plasma, showed that the aptasensor and the standard ELISA method quantified similar OPN levels (2.2 ± 0.7 and 1.7 ± 0.1 nM, respectively). Thus, our aptasensor coupled with SWV represents a promising alternative for the detection of relevant breast cancer biomarkers.

Clinicopathological Significance of Osteopontin in Cholangiocarcinoma Cases

Cholangiocarcinoma (CCA) is generally a rare primary liver tumor of the bile duct with extremely poor clinical outcomes due to late diagnosis. Osteopontin (OPN) is the most abundant expressed gene in intrahepatic CCA and its involvement in tumor aggressiveness suggests it could be a useful prognostic biomarker. However, the prognostic significance of OPN expression in CCA is still controversial. We therefore immunohistochemically studied OPN expression in 354 resected CCAs and correlated the results with patient clinicopathological parameters. OPN expression was separately scored according to the percentage of cancer cells or degree of stromal tissue staining and classified as low (score 0-1) and high (score 2-3). OPN expression in CCA cells was found in 177 out of 354 patients (56.5%), whereas stroma was positive in 185 out of 354 patients (52.3%). Univariate analysis with several of the aforementioned parameters revealed that stromal but not cancer cell OPN expression was significantly associated with tumor size, tumor direct invasion into normal liver parenchyma, regional lymph node metastasis and higher staging. The combination of cancer cell and stromal OPN expression demonstrated a positive trend for linkage with lymph node metastasis. Multivariate analysis identified gender, the presence of lymphatic permeation and lymph node metastasis, but not OPN expression, as independent prognostic factors. This study confirms the presence of stromal OPN expression in tumor aggressiveness but not survival in CCA patients.

Development of an electrochemical RNA-aptasensor to detect human osteopontin

Electrochemical aptasensors may be used to detect protein biomarkers related to tumor activity. Osteopontin (OPN), a protein present in several body fluids, has been suggested as a potential biomarker since its overexpression seems to be associated with breast cancer progression and metastasis. In this work, a simple and label-free voltammetric aptasensor for the detection of OPN, using an RNA aptamer previously reported to have affinity for human OPN as the molecular recognition element, and the ferro/ferricyanide solution as a redox probe, was developed. The RNA aptamer was synthetized and immobilized in a working microelectrode gold surface (diameter of 0.8mm) of a screen-printed strip with a silver pseudo-reference electrode and a gold counter electrode. The electrochemical behavior of the electrode surface after each preparation step of the aptasensor was studied using cyclic voltammetry and square wave voltammetry. The resulting voltammetric aptasensor was used to detect OPN in standard solutions. Cyclic voltammetry results showed that the aptasensor has reasonable detection and quantification limits (3.7 ± 0.6 nM and 11 ± 2 nM, respectively). Indeed, the detection limit falls within the osteopontin levels reported in the literature for patients with metastatic breast cancer. Moreover, the aptasensor is able to selectively detect the target protein in the presence of other interfering proteins, except for thrombin. Considering the overall results, a possible application of the aptasensor for cancer prognosis may be foreseen in a near future.

Proteins involved in regulating bone invasion in skull base meningiomas

Background

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

Methods

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

Results

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

Conclusions

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

Expressions of Osteopontin (OPN), ανβ3 and Pim-1 Associated with Poor Prognosis in Non-small Cell Lung Cancer (NSCLC)

OBJECTIVE

To examine the expressions of osteopontin (OPN), (α) (ν) (β) (3) and Pim-1 in non-small cell lung cancer (NSCLC), and investigate their potential pathogenic roles in the development of NSCLC.

METHODS

Immunohistochemistry was used to examine the expressions of OPN, (α) (ν) (β) (3) and Pim-1 in cohort (136 cases) of NSCLC samples and their adjacent normal lung tissue specimens. Statistical analysis was performed to evaluate the relationships among expressions of OPN, (α) (ν) (β) (3) and Pim-1 and their associations with patients clinico- pathological parameters.

RESULTS

The expressions of OPN and Pim-1 were predominantly observed in cytoplasm. The expression of (α) (ν) (β) (3) was mostly detected in cytoplasm and/or membrane. In NSCLC samples, the positive rates of OPN, (α) (ν) (β) (3) and Pim-1 expressions were 68.4% (93/136), 77.2% (105/136) and 57.4% (78/136), respectively. In normal lung tissues, in contrast, the positive rates of OPN, (α) (ν) (β) (3) and Pim-1 were 24.0% (12/50), 26.0% (13/50) and 16.0% (8/50), respectively. There were significant differences of the positive expression rates of OPN, (α) (ν) (β) (3) and Pim-1 between NSCLCs samples and normal lung tissues (P<0.01). In addition, the positive expression of OPN, (α) (ν) (β) (3) and Pim-1 in NSCLCs samples was significantly associated with increased pathological grade, lymph node metastasis and advanced clinical stage (P<0.01), and they were independent of other clinicopathological parameters (P>0.05). Furthermore, a significantly positive correlation between the expression of OPN and (α) (ν) (β) (3) (r=0.38, P<0.01), OPN and Pim-1 (r=0.37, P<0.01), or (α) (ν) (β) (3) and Pim-1 (r=0.20, P<0.05) was evaluated in our NSCLC cohort.

CONCLUSION

OPN, (α) (ν) (β) (3) and Pim-1 proteins are frequently overexpressed in NSCLC, and they may play important roles in the development and/or progression of NSCLC.

Overexpression of osteopontin, αvβ3 and Pim-1 associated with prognostically important clinicopathologic variables in non-small cell lung cancer

In this study, we examined the expression of osteopontin (OPN), αvβ3 and Pim-1 in non-small cell lung cancer (NSCLC) and investigated the potential clinical implications of their expression patterns in NSCLC. Immunohistochemical assays were used to examine the protein expression of OPN, αvβ3 and Pim-1 in 208 NSCLC samples and their adjacent normal lung tissue specimens. Statistical analyses were performed to evaluate the relationships between OPN, αvβ3 and Pim-1 expression patterns, and their association with the clinical-pathological parameters of NSCLC patients. In NSCLC tissues, the positive rates of OPN, αvβ3 and Pim-1 expression were 67.8% (141/208), 76.0% (158/208) and 58.7% (122/208), respectively. However, in the adjacent normal lung tissues, the positive rates of OPN, αvβ3 and Pim-1 were 20.2% (42/208), 24.0% (50/208) and 14.9% (31/208), respectively. The differences in the positive expression rates of OPN, αvβ3 and Pim-1 between NSCLCs and the adjacent normal lung tissues were all significant (P<0.01). Additionally, the positive expression of OPN, αvβ3 and Pim-1 in NSCLCs was associated with an increase in pathological grade, lymph node metastasis and advanced clinical stage (all P<0.01). Furthermore, associations between the expression of OPN and αvβ3, OPN and Pim-1, and αvβ3 and Pim-1 were also observed in our NSCLC cohort (all P<0.01). The OPN, αvβ3 and Pim-1 proteins are frequently overexpressed in NSCLC and are associated with some clinicopathologic variables that are of known prognostic importance in NSCLC, suggesting that they may play an important role in the development and/or progression of NSCLC.

Combination of haptoglobin and osteopontin could predict colorectal cancer hepatic metastasis

PURPOSE

This study aimed to identify novel molecular markers for the early detection of colorectal cancer liver metastasis.

METHODS

Genes related to hepatic metastasis were screened from the Oncomine database. The candidate markers were tested by immunohistochemistry, and their predictive accuracy was assessed by the cross-validation method and an independent test set.

RESULTS

We got three datasets containing 2,973 genes that were highly expressed in primary colon cancer tissues compared with non-metastatic colon cancer tissues and identified 7 candidate molecules for immunohistochemical validation. A total of 213 colorectal cancer samples were randomly divided into a training set (113 cases) and a blind testing set (100 cases). In the training set, immunohistochemical analysis showed that HP, OPN, and PTGIS expression were significantly higher in the hepatic metastasis group than in the non-metastasis group. Logistic regression analysis showed that HP and OPN levels in primary tumors and lymph node metastasis status were the only significant (P<0.05) parameters for detecting liver metastasis. The predictive accuracy of markers was assessed by the cross-validation method and an independent test set. In leave-one-out cross-validation, the two markers combined with clinicopathologic features resulted in 91.2% sensitivity and 96.4% specificity for hepatic metastasis detection. In an independent test set, the combination achieved 94.5% sensitivity and 88.9% specificity for predicting the hepatic metastasis of colorectal cancer.

CONCLUSIONS

Our results suggest that combined HP and OPN expression levels are significantly related to liver metastasis and prognosis, and, if this is validated, they could be used as accurate predictors of liver metastasis in colorectal cancer.

Osteopontin as a key mediator for vasculogenic mimicry in hepatocellular carcinoma

Osteopontin (OPN) is overexpressed in a variety of cancers including hepatocellular carcinoma (HCC), and is likely involved in the process of vasculogenic mimicry (VM) in some tumor cells. In this study, we explored whether OPN plays a role for VM in HCC. Metastatic MHCC97-H human HCC cells and non-metastatic Hep3B human HCC cells were compared for their abilities to establish VM. Three dimensional-culture assays showed that MHCC97-H cells but not Hep3B cells were able to form the chord-like structure that represents VM. Real-time RT-PCR arrays were used to detect gene expression profiles of the two HCC cell lines in three-dimensional culture. PCR array analyses revealed the increased expression of OPN in MHCC97-H cells forming VM compared with Hep3B cells. Small interfering RNA was employed to investigate whether OPN knockdown could influence VM, and the expression of matrix metalloproteinase (MMP)-2, MMP-9 and urokinase-type plasminogen activator (uPA) in MHCC97-H cells. OPN knockdown resulted in a significant decrease in the ability of MHCC97-H cells to form VM, which was accompanied by the down-regulation of MMP-2 and uPA expression. Furthermore, human HCC tissue samples were studied by immunohistochemistry to analyze the correlations between VM and the expression of OPN, MMP-2 and uPA. There existed significant positive correlations between VM and the expression of OPN, MMP-2 and uPA in HCC tissue samples. In conclusion, OPN is required for VM in HCC cells, and its action may be associated with activation of MMP-2 and uPA. OPN-targeted therapeutics may be useful for patients with advanced HCC.

Transcription factor c-Myb promotes the invasion of hepatocellular carcinoma cells via increasing osteopontin expression

Background

Specific gene expression is tightly regulated by various transcription factors. Osteopontin (OPN) is a phosphoprotein that mediates hepatocellular carcinoma (HCC) progression and metastasis. However, the mechanism of OPN up-regulation in HCC metastasis remains to be clarified.

Methods

Oligonucleotide array-based transcription factor assays were applied to compare different activities of transcription factors in two human HCC cell lines with different OPN expression levels. The effects of one selected transcription factor on OPN expression were further evaluated.

Results

Eleven transcription factors were over-expressed in metastatic HCC cell line HCCLM6 cells whereas twelve transcription factors were down-regulated. Electrophoretic mobility shift assays (EMSA) and reporter gene assays showed that one of up-regulated transcription factors c-Myb could bind the OPN promoter and increase its transcription activity. In addition, small interfering RNA targeting c-Myb could inhibit OPN expression and significantly decrease migration and invasion of HCCLM6 cells in vitro.

Conclusion

Our data first demonstrate that c-Myb has a functionally important role in the regulation of OPN expression in HCC cells, suggesting that c-Myb might be a new target to control HCC metastasis.

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.

Building a better understanding of the intracellular tyrosine kinase PTK6 - BRK by BRK

Protein tyrosine kinase 6 (PTK6), also referred to as breast tumor kinase BRK, is a member of a distinct family of kinases that is evolutionarily related to the SRC family of tyrosine kinases. While not expressed in the normal mammary gland, PTK6 expression is detected in a large proportion of human mammary gland tumors. In breast tumor cells, PTK6 promotes growth factor signaling and cell migration. PTK6 expression is also increased in a number of other epithelial tumors, including ovarian and colon cancer. In contrast, PTK6 is expressed in diverse normal epithelia, including the linings of the gastrointestinal tract, skin and prostate, where its expression correlates with cell cycle exit and differentiation. Disruption of the mouse Ptk6 gene leads to increased growth and impaired differentiation in the small intestine that is accompanied by increased AKT and Wnt signaling. Following total body irradiation, PTK6 expression is induced in proliferating progenitor cells of the intestine, where it plays an essential role in DNA-damage induced apoptosis. A distinguishing feature of PTK6 is its flexibility in intracellular localization, due to a lack of amino-terminal myristoylation/palmitoylation. Recently a number of substrates of PTK6 have been identified, including nuclear RNA-binding proteins and transcription factors. We discuss PTK6 signaling, its apparent conflicting roles in cancer and normal epithelia, and its potential as a therapeutic target in epithelial cancers.