Calcitonin receptors, bone sialoprotein and osteopontin are expressed in primary breast cancers

Osteopontin Levels in Patients with Squamous Metastatic Head and Neck Cancer

Background and Objectives: Increased osteopontin (OPN) concentrations in the plasma of patients with head and neck squamous cancer (HNSCC) have diagnostic significance, and it can indicate more aggressive biological behavior of cancer. The aim of this study was to determine OPN levels in patients with HNSCC of different primary locations and to assess its prognostic significance in metastasis development. Materials and Methods: This cohort study included 45 patients (41 male and 4 female patients) with HNSCC with different primary localization of head and neck. All patients underwent surgery—neck dissection. All patients were categorized according to the histological findings of the resected material and tumor–node–metastasis (TNM) classification system. After surgery, N categories were determined on the basis of histological features of resected material. Results: The histological findings of our patients showed: N0 in 11 patients, N1 in 8 patients, N2a in 4 patients, N2b in 14 patients and N2c in 8 patients. Plasma OPN values in all study participants ranged from 2.24 to 109.10 ng/mL. OPN levels in plasma of patients with negative nodes compared to the group of patients with positive nodes in the neck differed significantly (16.89 ng/mL to 34.08 ng/mL, respectively; p = 0.03). There were significantly lower OPN plasma levels in the group of subjects with histologically positive one lymph node in the neck (N1) compared to the group of patients with N2b histologically positive findings of resected neck material (10.4 ng/mL to 43.9 ng/mL, respectively; p = 0.02). Conclusions: The results have shown that growing N degrees of positive neck nodes classification were accompanied by growing values of plasma osteopontin. Osteopontin might be important for the development of neck metastases.

Building the case for the calcitonin receptor as a viable target for the treatment of glioblastoma

Researchers are actively seeking novel targeted therapies for the brain tumour glioblastoma (GBM) as the mean survival is less than 15 months. Here we discuss the proposal that the calcitonin receptor (CT Receptor), expressed in 76-86% of patient biopsies, is expressed by both malignant glioma cells and putative glioma stem cells (GSCs), and therefore represents a potential therapeutic target. Forty-two per cent (42%) of high-grade glioma (HGG; representative of GSCs) cell lines express CT Receptor protein. CT Receptors are widely expressed throughout the life cycle of organisms and in some instances promote apoptosis. Which of the common isoforms of the CT Receptor are predominantly expressed is currently unknown, but a functional response to cell stress of the insert-positive isoform is hypothesised. A model for resistant malignancies is one in which chemotherapy plays a direct role in activating quiescent stem cells for replacement of the tumour tissue hierarchy. The putative role that the CT Receptor plays in maintenance of quiescent cancer stem cells is discussed in view of the activation of the Notch-CT Receptor-collagen V axis in quiescent muscle (satellite) stem cells. The pharmacological CT response profiles of four of the HGG cell lines were reported. Both CT responders and non-responders were sensitive to an immunotoxin based on an anti-CT Receptor antibody. The CALCR mRNA exhibits alternative splicing commonly associated with cancer cells, which could result in the atypical pharmacology exhibited by CT non-responders and an explanation of tumour suppression. Due to the inherent instability of CALCR mRNA, analysis of CT Receptor protein in patient samples will lead to improved data for the expression of CT Receptor in GBM and other cancers, and an understanding of the role and activity of the splice variants. This knowledge will aid the effective targeting of this receptor for treatment of GBM.

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.

IDK1 is a rat monoclonal antibody against hypoglycosylated bone sialoprotein with application as biomarker and therapeutic agent in breast cancer skeletal metastasis

Changes in glycosylation are salient features of cancer cells. Here, we report on the diagnostic and therapeutic properties of IDK1, an antibody against tumour associated, hypoglycosylated bone sialoprotein (hypo‐BSP). The affinity of the rat monoclonal antibody IDK1 for hypo‐BSP, as determined by microscale thermophoresis, was three orders of magnitude higher than for mature BSP, whereas the mouse monoclonal antibody used had similar affinity for both BSP forms. IDK1 showed no activity against the proliferation or migration of normal or cancer cells growing in vitro. In vivo, however, IDK1 caused dose‐dependent regression of soft tissue and skeletal lesions in nude rats harbouring human MDA‐MB‐231 cells. At optimal dose, 80% of the treated rats showed complete remission of all tumour lesions. Analysis of BSP expression in vitro by fluorescence‐activated cell sorting (FACS) and immunocytochemistry showed basal levels of this protein, which were visible only in a fraction of these cells. Cells of the metastatic cell lines MDA‐MB‐231 and PC‐3 were more often positive for hypo‐BSP. In addition, there was co‐expression of both forms in some cells, but almost no co‐localization; rather, hypo‐BSP was present in the nucleus, and mature BSP was detected extra‐cellularly. Normal osteoblasts and osteoclasts were negative for hypo‐BSP. Breast cancer tissue, however, showed strong expression of mature BSP, which was present intra‐cellularly as well as in vesicles outside cells. Hypo‐BSP was present mainly in lesions from skeletal sites, thus explaining the antineoplastic activity of IDK1, which was high in lesions growing in the vicinity of the skeleton but low in lesions growing subcutaneously. Finally, hypo‐BSP was detected in specimens from breast cancer patients, with a significantly greater intensity in skeletal metastases as compared to the respective primary cancers. In conclusion, IDK‐1 is an antibody with diagnostic and therapeutic applications in skeletal metastases of breast cancer.

Calcitonin receptor expression in medullary thyroid carcinoma

Background

Calcitonin expression is a well-established marker for medullary thyroid carcinoma (MTC); yet the role of calcitonin receptor (CTR), its seven-transmembrane G-protein coupled receptor, remains to be established in C-cells derived thyroid tumors. The aim of this work was to investigate CTR expression in MTC and to correlate such expression with clinicopathological features in order to evaluate its possible role as a prognostic indicator of disease aggressiveness and outcome.

Methods

Calcitonin receptor expression was analyzed in a series of 75 MTCs by immunohistochemistry, and by qPCR mRNA quantification in specimens from four patients. Statistical tests were used to evaluate the correlation between CTR expression and the clinicopathological and molecular characteristics of patients and tumors.

Results

Calcitonin receptor expression was detected in 62 out of 75 samples (82.7%), whereas 13 of the 75 samples (17.3%) were completely negative. CTR expression was significantly associated with expression of cytoplasmatic phosphatase and tensin homologue deleted on chromosome 10 and osteopontin, as well as with wild type RET/RAS genes and absence of tumor stroma, suggesting that CTR expression do not associate with clinicopathological signs of worse prognosis.

Discussion

Calcitonin receptor expression appears to be associated in MTC with more differentiated status of the neoplastic cells.

Dianthin-30 or gelonin versus monomethyl auristatin E, each configured with an anti-calcitonin receptor antibody, are differentially potent in vitro in high-grade glioma cell lines derived from glioblastoma

We have reported that calcitonin receptor (CTR) is widely expressed in biopsies from the lethal brain tumour glioblastoma by malignant glioma and brain tumour-initiating cells (glioma stem cells) using anti-human CTR antibodies. A monoclonal antibody against an epitope within the extracellular domain of CTR was raised (mAb2C4) and chemically conjugated to either plant ribosome-inactivating proteins (RIPs) dianthin-30 or gelonin, or the drug monomethyl auristatin E (MMAE), and purified. In the high-grade glioma cell line (HGG, representing glioma stem cells) SB2b, in the presence of the triterpene glycoside SO1861, the EC50 for mAb2C4:dianthin was 10.0 pM and for mAb2C4:MMAE [antibody drug conjugate (ADC)] 2.5 nM, 250-fold less potent. With the cell line U87MG, in the presence of SO1861, the EC50 for mAb2C4:dianthin was 20 pM, mAb2C4:gelonin, 20 pM, compared to the ADC (6.3 nM), which is >300 less potent. Several other HGG cell lines that express CTR were tested and the efficacies of mAb2C4:RIP (dianthin or gelonin) were similar. Co-administration of the enhancer SO1861 purified from plants enhances lysosomal escape. Enhancement with SO1861 increased potency of the immunotoxin (>3 log values) compared to the ADC (1 log). The uptake of antibody was demonstrated with the fluorescent conjugate mAb2C4:Alexa Fluor 568, and the release of dianthin-30:Alexa Fluor488 into the cytosol following addition of SO1861 supports our model. These data demonstrate that the immunotoxins are highly potent and that CTR is an effective target expressed by a large proportion of HGG cell lines representative of glioma stem cells and isolated from individual patients.

Soluble bone-derived osteopontin promotes migration and stem-like behavior of breast cancer cells

Breast cancer is a leading cause of cancer death in women, with the majority of these deaths caused by metastasis to distant organs. The most common site of breast cancer metastasis is the bone, which has been shown to provide a rich microenvironment that supports the migration and growth of breast cancer cells. Additionally, growing evidence suggests that breast cancer cells that do successfully metastasize have a stem-like phenotype including high activity of aldehyde dehydrogenase (ALDH) and/or a CD44⁺CD24^- phenotype. In the current study, we tested the hypothesis that these ALDH^hiCD44⁺CD24^- breast cancer cells interact with factors in the bone secondary organ microenvironment to facilitate metastasis. Specifically, we focused on bone-derived osteopontin and its ability to promote the migration and stem-like phenotype of breast cancer cells. Our results indicate that bone-derived osteopontin promotes the migration, tumorsphere-forming ability and colony-forming ability of whole population and ALDH^hiCD44⁺CD24^- breast cancer cells in bone marrow-conditioned media (an ex vivo representation of the bone microenvironment) (p≤0.05). We also demonstrate that CD44 and RGD-dependent cell surface integrins facilitate this functional response to bone-derived osteopontin (p≤0.05), potentially through activation of WNK-1 and PRAS40-related pathways. Our findings suggest that soluble bone-derived osteopontin enhances the ability of breast cancer cells to migrate to the bone and maintain a stem-like phenotype within the bone microenvironment, and this may contribute to the establishment and growth of bone metastases.

Osteopontin: its potential role in cancer of children and young adults

Objective: Osteopontin (OPN) is aglyco-phosphoprotein, involved in tissue remodeling, inflammation and boneresorption. In various adult neoplasms OPN was shown to correlate with cancer progression, invasiveness and metastasis. Aim: to define the role of OPN in malignancies of children and young adults. Material and methods: a structured PubMed and Google Scholar literature analysis based on reports published in English between I'1995 and XII'2015. Results: 14 studies (four on hematological malignancies, four on bone tumors, three on CNS tumors, two on dendritic proliferative diseases and one on renal tumors) were identified. Higher levels of serum and cerebro-spinal fluid OPN protein, and high expressions of OPN mRNA and SPP1 gene were present in more aggressive and advanced childhood malignancies. In children with acute lymphoblastic leukemia with CNS involvement and with atypical teratoid/rhabdoid tumor (AT/RT) and medulloblastoma, the serum and CSF OPN levels reflected tumor bulk and response to therapy, while in children with AT/RT and multisystem Langerhans cell histiocytosis with high-risk organs involvement, high OPN serum levels correlated with poorer survival. To the contrary, in osteosarcoma, high OPN mRNA and SPP1 gene expressions correlated with better survival and good response to chemotherapy. Conclusions: The literature review suggests that OPN may play important roles in the development and progression of selected cancers of children and young adults, including acute lymphoblastic leukemia, malignant gliomas, AT/RT and Langerhans cell histiocytosis. However, limited number of published studies prevents from definite concluding on the clinical utility of OPN as a marker of diagnosis, prognosis and treatment monitoring in these pediatric cancers. Further studies performed in more numerous groups of patients with particular types of cancers of children and young adults are warranted.

A novel ligand of calcitonin receptor reveals a potential new sensor that modulates programmed cell death

We have discovered that the accumulation of an anti-calcitonin receptor (anti-CTR) antibody conjugated to a fluorophore (mAb2C4:AF568) provides a robust signal for cells undergoing apoptotic programmed cell death (PCD). PCD is an absolute requirement for normal development of metazoan organisms. PCD is a hallmark of common diseases such as cardiovascular disease and tissue rejection in graft versus host pathologies, and chemotherapeutics work by increasing PCD. This robust signal or high fluorescent events were verified by confocal microscopy and flow cytometry in several cell lines and a primary culture in which PCD had been induced. In Jurkat cells, GBM-L2 and MG63 cells, the percentage undergoing PCD that were positive for both mAb2C4:AF568 and annexin V ranged between 70 and >90%. In MG63 cells induced for the preapoptotic cell stress response (PACSR), the normal expression of α-tubulin, a key structural component of the cytoskeleton, and accumulation of mAb2C4:AF568 were mutually exclusive. Our data support a model in which CTR is upregulated during PACSR and recycles to the plasma membrane with apoptosis. In cells committed to apoptosis (α-tubulin negative), there is accumulation of the CTR-ligand mAb2C4:AF568 generating a high fluorescent event. The reagent mAb2C4:AF568 effectively identifies a novel event linked to apoptosis.

A Molecular View of Pathological Microcalcification in Breast Cancer

Breast microcalcification is a potential diagnostic indicator for non-palpable breast cancers. Microcalcification type I (calcium oxalate) is restricted to benign tissue, whereas type II (calcium hydroxyapatite) occurs both in benign as well as in malignant lesions. Microcalcification is a pathological complication of the mammary gland. Over the past few decades, much attention has been paid to exploit this property, which forms the basis for advances in diagnostic procedures and imaging techniques. The mechanism of its formation is still poorly understood. Hence, in this paper, we have attempted to address the molecular mechanism of microcalcification in breast cancer. The central theme of this communication is "how a subpopulation of heterogeneous breast tumor cells attains an osteoblast-like phenotype, and what activities drive the process of pathophysiological microcalcification, especially at the invasive or infiltrating front of breast tumors". The role of bone morphogenetic proteins (BMPs) and tumor associated macrophages (TAMs) along with epithelial to mesenchymal transition (EMT) in manipulating this pathological process has been highlighted. Therefore, this review offers a novel insight into the mechanism underlying the development of microcalcification in breast carcinomas.

Osteopontin Involves Cisplatin Resistance and Poor Prognosis in Oral Squamous Cell Carcinoma

Background. Osteopontin (OPN) is a multifunctional cytokine involved in cell survival, migration, and adhesion. However, its role in chemosensitivity in locally advanced oral squamous cell carcinoma (OSCC) in humans has not yet been investigated. Methods. We enrolled 121 patients with locally advanced stage IVA/B OSCC receiving cisplatin-based IC followed by CCRT from January 1, 2006, through January 1, 2012. Immunohistochemistry was used to assess OPN expression in OSCC patients' biopsy specimens from paraffin blocks before treatment. In addition, MTT/colony formation assay was used to estimate the influence of OPN in an oral cancer cell line treated with cisplatin. Results. Of the 121 patients, 94 had positive OPN findings and 52 responded to IC followed by CCRT. Positive osteopontin immunostaining also correlated significantly with positive N status/TNM stage/male gender and smoking. Univariate analyses showed that patients whose tumors had a low expression of OPN were more likely to respond to chemotherapy and have a significantly better OS than those whose tumors had a high expression of OPN. Multivariate analysis revealed that prolonged survival was independently predicted for patients with stage IVA disease, negative lymph nodes, and negative expressions of OPN and for those who received chemotherapy with Docetaxel/cisplatin/fluorouracil (TPF). An oral cancer line stimulated with OPN exhibited a dose-dependent resistance to cisplatin treatment. Conversely, endogenous OPN depletion by OPN-mediated shRNA increased sensitivity to cisplatin. Conclusions. A positive expression of OPN predicts a poor response and survival in patients with locally advanced stage IVA/B OSCC treated with cisplatin-based IC followed by CCRT.

Sustained conditional knockdown reveals intracellular bone sialoprotein as essential for breast cancer skeletal metastasis

Increased bone sialoprotein (BSP) serum levels are related to breast cancer skeletal metastasis, but their relevance is unknown. We elucidated novel intracellular BSP functions by a conditional knockdown of BSP. Conditional MDA-MB-231 subclones were equipped with a novel gene expression cassette containing a tet-regulated miRNA providing knockdown of BSP production. These clones were used to assess the effect of BSP on morphology, proliferation, migration, colony formation and gene expression in vitro, and on soft tissue and osteolytic lesions in a xenograft model by three imaging methods. BSP knockdown caused significant anti-proliferative, anti-migratory and anti-clonogenic effects in vitro (p<0.001). In vivo, significant decreases of soft tissue and osteolytic lesions (p<0.03) were recorded after 3 weeks of miRNA treatment, leading to complete remission within 6 weeks. Microarray data revealed that 0.3% of genes were modulated in response to BSP knockdown. Upregulated genes included the endoplasmic reticulum stress genes ATF3 and DDIT3, the tumor suppressor gene EGR1, ID2 (related to breast epithelial differentiation), c-FOS and SERPINB2, whereas the metastasis associated genes CD44 and IL11 were downregulated. Also, activation of apoptotic pathways was demonstrated. These results implicate that intracellular BSP is essential for breast cancer skeletal metastasis and a target for treating these lesions.

Bone sialoprotein and osteopontin in bone metastasis of osteotropic cancers

The mechanisms underlying malignant cell metastasis to secondary sites such as bone are complex and no doubt multifactorial. Members of the small integrin-binding ligand N-linked glycoproteins (SIBLINGs) family, particularly bone sialoprotein (BSP) and osteopontin (OPN), exhibit multiple activities known to promote malignant cell proliferation, detachment, invasion, and metastasis of several osteotropic cancers. The expression level of BSP and OPN is elevated in a variety of human cancers, particularly those that metastasize preferentially to the skeleton. Recent studies suggest that the "osteomimicry" of malignant cells is not only conferred by transmembrane receptors bound by BSP and OPN, but includes the "switch" in gene expression repertoire typically expressed in cells of skeletal lineage. Understanding the role of BSP and OPN in tumor progression, altered pathophysiology of bone microenvironment, and tumor metastasis to bone will likely result in development of better diagnostic approaches and therapeutic regimens for osteotropic malignant diseases.

Should EMT of Cancer Cells Be Understood as Epithelial-Myeloid Transition?

Cancer cells express epithelial markers, and when progressing in malignancy they may express markers of the mesenchymal cell type. Therefore an epithelial-mesenchymal transition of the cancer cells is assumed. However the mesenchymal markers can equally well be interpreted as myeloid markers since they are common in both types of cell lineages. Moreover, cancer cells express multiple specific markers of the myeloid lineages thus giving rise to the hypothesis that the transition of cancer cells may be from epithelial to myeloid cells and not to mesenchymal cells. This interpretation would better explain why cancer cells, often already in their primary cancer site, frequently show properties common to those of macrophages, platelets and pre-/osteoclasts.

Paracrine signaling by progesterone

Steroid hormones coordinate and control the development and function of many organs and are implicated in many pathological processes. Progesterone signaling, in particular, is essential for several important female reproductive functions. Physiological effects of progesterone are mediated by its cognate receptor, expressed in a subset of cells in target tissues. Experimental evidence has accumulated that progesterone acts through both cell intrinsic as well as paracrine signaling mechanisms. By relegating the hormonal stimulus to paracrine signaling cascades the systemic signal gets amplified locally and signaling reaches different cell types that are devoid of hormone receptors. Interestingly, distinct biological responses to progesterone in different target tissues rely on several tissue-specific and some common paracrine factors that coordinate biological responses in different cell types. Evidence is forthcoming that the intercellular signaling pathways that control development and physiological functions are important in tumorigenesis.

Contribution of bone tissue modulus to breast cancer metastasis to bone

Certain tumors, such as breast, frequently metastasize to bone where they can induce bone destruction. Currently, it is well-accepted that the tumor cells are influenced by other cells and growth factors present in the bone microenvironment that lead to tumor-induced bone disease. Over the past 20 years, many groups have studied this process and determined the major contributing factors; however, these results do not fully explain the changes in gene expression and cell behavior that occur when tumor cells metastasize to bone. More recently, groups studying metastasis from soft tissue sites have determined that the rigidity of the microenvironment, which increases during tumor progression in soft tissue, can regulate tumor cell behavior and gene expression. Therefore, we began to investigate the role of the rigid bone extracellular matrix in the regulation of genes that stimulate tumor-induced bone disease. We found that the rigidity of bone specifically regulates parathyroid hormone-related protein (PTHrP) and Gli2 expression in a transforming growth factor β (TGF-β) and mechanotransduction-dependent mechanism. In this review, we summarize the mechanotransduction signaling pathway and how this influences TGF-β signaling and osteolytic gene expression.

Elevated content of osteopontin in plasma and tumor tissues of patients with laryngeal and hypopharyngeal carcinoma associated with metastasis and prognosis

The aim of this study was to evaluate the usefulness of osteopontin (OPN) expression level in plasma and tumor tissues of patients with laryngeal and hypopharyngeal squamous-cell carcinoma for predicting metastasis and survival of this tumor. The OPN expression in tumor tissues was detected by immunohistochemical staining in a tissue microarray of laryngeal and hypopharyngeal carcinomas, and the OPN level in plasma was measured by ELISA. The expression levels of OPN in plasma and tumor tissues were associated with clinicopathological features and survival of laryngeal and hypopharyngeal carcinomas. Results showed that the OPN expression quantitation either in tissues or plasma was significantly correlated with differentiation and lymphatic metastasis of the laryngeal and hypopharyngeal carcinoma. Elevated OPN level of plasma and tissues was significantly associated with poor survival. In conclusion, elevated OPN level in plasma and tumor tissues was significantly associated with metastasis and survival of laryngeal and hypopharyngeal carcinomas. Elevated OPN level in plasma and tumor tissues may become a useful indicator of prognosis for laryngeal and hypopharyngeal cancers.

Advances in the biology of bone metastasis: how the skeleton affects tumor behavior

It is increasingly evident that the microenvironment of bone can influence the cancer phenotype in many ways that favor growth in bone. The ability of cancer cells to adhere to bone matrix and to promote osteoclast formation are key requirements for the establishment and growth of bone metastases. Several cytokine products of breast cancers (e.g. PTHrP, IL-11, IL-8) have been shown to act upon host cells of the bone microenvironment to promote osteoclast formation, allowing for excessive bone resorption. The increased release of matrix-derived growth factors, especially TGF-β, acts back upon the tumor to facilitate further tumor expansion and enhance cytokine production, and also upon osteoblasts to suppress bone formation. This provides a self-perpetuating cycle of bone loss and tumor growth within the skeleton. Other contributing factors favoring tumor metastasis and colonization in bone include the unique structure and stiffness of skeletal tissue, along with the diverse cellular composition of the marrow environment (e.g. bone cells, stromal fibroblasts, immune cells), any of which can contribute to the phenotypic changes that can take place in metastatic deposits that favor their survival. Additionally, it is also apparent that breast cancer cells begin to express different bone specific proteins as well as proteins important for normal breast development and lactation that allow them to grow in bone and stimulate bone destruction. Taken together, these continually emerging areas of study suggest new potential pathways important in the pathogenesis of bone metastasis and potential areas for targeting therapeutics.

Integrins and bone metastasis: integrating tumor cell and stromal cell interactions

Integrins on both tumor cells and the supporting host stromal cells in bone (osteoclasts, new blood vessels, inflammatory cells, platelets and bone marrow stromal cells) play key roles in enhancing bone metastasis. Tumor cells localize to specific tissues through integrin-mediated contacts with extracellular matrix and stromal cells. Integrin expression and signaling are perturbed in cancer cells, allowing them to "escape" from cell-cell and cell-matrix tethers, invade, migrate and colonize within new tissues and matrices. Integrin signaling through αvβ3 and VLA-4 on tumor cells can promote tumor metastasis to and proliferation in the bone microenvironment. Osteoclast (OC) mediated bone resorption is a critical component of bone metastasis and can promote tumor growth in bone and αvβ3 integrins are critical to OC function and development. Tumors in the bone microenvironment can recruit new blood vessel formation, platelets, pro-tumor immune cells and bone marrow stromal cells that promote tumor growth and invasion in bone. Integrins and their ligands play critical roles in platelet aggregation (αvβ3 and αIIbβ3), hematopoietic cell mobilization (VLA-4 and osteopontin), neoangiogenesis (αvβ3, αvβ5, α6β4, and β1 integrin) and stromal function (osteopontin and VLA-4). Integrins are involved in the pathogenesis of bone metastasis at many levels and further study to define integrin dysregulation by cancer will yield new therapeutic targets for the prevention and treatment of bone metastasis.

Functional expression of the calcitonin receptor by human T and B cells

The calcitonin receptor (CTR) is a seven-transmembrane-domain G-protein-coupled receptor that regulates calcium metabolism and bone resorption by osteoclasts. Here we demonstrate that high levels are expressed by normal human T and B lymphocytes from tonsils and peripheral blood in relation to their activation status, as CTR(+) T cells are prone to produce IFN-gamma after TCR stimulation. The receptor is also highly expressed on B cells from chronic lymphocytic leukemia patients, thus suggesting a correlation between its expression, their proliferative extent as well as their memory, antigen-experienced phenotype. Moreover, we found that binding of the receptor with salmon calcitonin induces an increase of intracellular calcium(2+) in peripheral lymphocytes. This effect is involved in several lymphocyte immune functions, as cytosolic calcium(2+) levels regulate both cell proliferation and cytokine production. In our hands, the increase of calcium(2+) levels by CTR binding with sCT induced a dose-dependent cell proliferation. We therefore suppose that expression of this functional receptor may contribute to the modulation of cytoplasmic calcium(2+) levels needed to regulate T and B cell activation and perhaps other immune functions.

Osteopontin is involved in the development of acquired chemo-resistance of cisplatin in small cell lung cancer

Osteopontin (OPN) is a multi-functional cytokine involved in cell survival, migration and adhesion which is associated with tumorigenesis, progression and metastasis. However, the role of OPN in chemo-sensitivity of human lung cancer has not yet been elucidated. The purpose of this study is to investigate the role of OPN in chemo-sensitivity of lung cancer cells. We developed a stable OPN transfectant (SBC-3/OPN) and a control transfectant (SBC-3/NEO) from human small cell lung cancer cell line, SBC-3. SBC-3/OPN cells were more resistant to cisplatin than SBC-3/NEO cells. Multi-drug resistance-associated protein (MRP) does not appear to be involved in the development of acquired chemo-resistance, since MRP inhibitor did not alter chemo-sensitivity. After exposure to cisplatin, the apoptotic SBC-3/OPN cells were reduced in number compared to SBC-3/NEO cells. Treatment with cisplatin revealed that the expression of anti-apoptotic protein, bcl-2, was down-regulated in SBC-3/NEO cells, while that of SBC-3/OPN cells was not altered. In contrast, pro-apoptotic protein, bax, was not altered in both SBC-3/OPN and SBC-3/NEO cells, thus bcl-2/bax ratio was decreased in SBC-3/NEO but not altered in SBC-3/OPN cells. Activation of caspase-3 and caspase-9 was increased in SBC-3/NEO cells, but not in SBC-3/OPN cells. Our results suggest that OPN enhances chemo-resistance of cisplatin in SBC-3 cells by suppressing bcl-2 protein down-regulation, thereby blocking the caspase-9- and caspase-3-dependent cell apoptosis.

Runx2 is expressed in human glioma cells and mediates the expression of galectin-3

Runx2 is a member of the Runx family of transcription factors (Runx1-3) with a restricted expression pattern. It has so far been detected predominantly in skeletal tissues where, inter alia, it regulates the expression of the beta-galactoside-specific lectin galectin-3. Here we show that, in contrast to Runx3, Runx1 and Runx2 are expressed in a variety of human glioma cells. Runx2 expression pattern in these cells correlated completely with that of galectin-3, but not with that of other galectins. A similar correlation in the expression pattern of galectin-3 and Runx2 transcripts was detected in distinct types of 70 primary neural tumors, such as glioblastoma multiforme, but not in others, such as gangliocytomas. In glioma cells, Runx2 is directly involved in the regulation of galectin-3 expression, as shown by RNAi and transcription factor binding assays demonstrating that Runx2 interacts with a Runx2-binding motif present in the human galectin-3 promoter. Knockdown of Runx2 was thus accompanied by a reduction of both galectin-3 mRNA and protein levels by at least 50%, dependent on the glial tumor cell line tested. Reverse transcriptase-polymerase chain reaction analyses, aimed at finding other potential target genes of Runx2 in glial tumor cells, revealed the presence of bone sialoprotein, osteocalcin, osteopontin, and osteoprotegerin. However, their expression patterns only partially overlap with that of Runx2. These data suggest a functional contribution of Runx-2-regulated galectin-3 expression to glial tumor malignancy.

A novel promoter regulates calcitonin receptor gene expression in human osteoclasts

The calcitonin receptor (CTR) is expressed in a wide variety of tissues and cell types. In bone, its expression is restricted to osteoclasts, the cells that mediate bone resorption. The human CTR (hCTR) gene has a complex structural organization that exhibits similarity to the porcine (pCTR) and mouse (mCTR) CTR genes. In these species, alternative splicing of a single gene generates multiple CTR isoforms that are distributed in both tissue-specific and species-specific patterns. However, the structural organization of the 5' putative regulatory region and transcriptional mechanisms responsible for tissue-specific expression of the different CTR isoforms are not fully defined. The present studies were undertaken to characterize the structural organization of the 5'-region of the hCTR and identify the regulatory regions involved in osteoclast-specific transcriptional activation. Analysis of mRNA prepared from human osteoclasts using reverse transcription-polymerase chain reaction (RT-PCR) and transient transfection of hCTR promoter-luciferase reporter constructs identified two regions in the 5'-flanking sequence of the hCTR gene that regulated CTR gene expression in osteoclasts. Both of these putative promoters were responsive to the osteoclast-inducing cytokine, receptor activator of NF-kappaB ligand (RANKL) and demonstrated trans-activation by the RANKL-induced transcription factor nuclear factor of activated T cells (NFATc1), consistent with a role in regulating CTR gene expression in osteoclasts.

Expression and function of the calcitonin receptor by myeloma cells in their osteoclast-like activity in vitro

Malignant plasma cells exert osteoclast-like activity in vitro. We investigated the function of the calcitonin (CT) receptor (R) on myeloma cells from patients and in myeloma cell lines. Primary myeloma cells expressed high CTR levels whereas the cell lines uniformly exposed the CTR-2 variant expressed by osteoclasts. Treatment of myeloma cell lines with CT modified the intracellular Ca(2+) and cAMP levels, suggesting the activation of both PKC and PKA pathways, and abrogated their bone resorptive property as erosive pits on osteologic substrates. Thus, the expression, sensitivity and function of CTR-2 in myeloma cells emphasize their osteoclast-like behavior in vitro.

Integrated pipeline for mass spectrometry-based discovery and confirmation of biomarkers demonstrated in a mouse model of breast cancer

Despite their potential to impact diagnosis and treatment of cancer, few protein biomarkers are in clinical use. Biomarker discovery is plagued with difficulties ranging from technological (inability to globally interrogate proteomes) to biological (genetic and environmental differences among patients and their tumors). We urgently need paradigms for biomarker discovery. To minimize biological variation and facilitate testing of proteomic approaches, we employed a mouse model of breast cancer. Specifically, we performed LC-MS/MS of tumor and normal mammary tissue from a conditional HER2/Neu-driven mouse model of breast cancer, identifying 6758 peptides representing >700 proteins. We developed a novel statistical approach (SASPECT) for prioritizing proteins differentially represented in LC-MS/MS datasets and identified proteins over- or under-represented in tumors. Using a combination of antibody-based approaches and multiple reaction monitoring-mass spectrometry (MRM-MS), we confirmed the overproduction of multiple proteins at the tissue level, identified fibulin-2 as a plasma biomarker, and extensively characterized osteopontin as a plasma biomarker capable of early disease detection in the mouse. Our results show that a staged pipeline employing shotgun-based comparative proteomics for biomarker discovery and multiple reaction monitoring for confirmation of biomarker candidates is capable of finding novel tissue and plasma biomarkers in a mouse model of breast cancer. Furthermore, the approach can be extended to find biomarkers relevant to human disease.

Small integrin binding ligand N-linked glycoprotein gene family expression in different cancers

PURPOSE

Members of the small integrin binding ligand N-linked glycoprotein (SIBLING) gene family have the capacity to bind and modulate the activity of matrix metalloproteinases (MMPs). The expression levels of five SIBLING gene family members [bone sialoprotein (BSP), osteopontin (OPN), dentin matrix protein 1 (DMP1), matrix extracellular phosphoglycoprotein (MEPE), and dentin sialophosphoprotein (DSPP)] and certain MMPs were determined using a commercial cancer array.

EXPERIMENTAL DESIGN

Cancer profiling arrays containing normalized cDNA from both tumor and corresponding normal tissues from 241 individual patients were used to screen for SIBLING and MMP expression in nine distinct cancer types.

RESULTS

Significantly elevated expression levels were observed for BSP in cancer of the breast, colon, stomach, rectum, thyroid, and kidney; OPN in cancer of the breast, uterus, colon, ovary, lung, rectum, and thyroid; DMP1 in cancer of the breast, uterus, colon, and lung; and dentin sialophosphoprotein in breast and lung cancer. The degree of correlation between a SIBLING and its partner MMP was found to be significant within a given cancer type (e.g., BSP and MMP-2 in colon cancer, OPN and MMP-3 in ovarian cancer; DMP1 and MMP-9 in lung cancer). The expression levels of SIBLINGs were distinct within subtypes of cancer (e.g., breast ductal tumors compared with lobular tumors). In general, SIBLING expression increased with cancer stage for breast, colon, lung, and rectal cancer.

CONCLUSIONS

These results suggest SIBLINGs as potential markers of early disease progression in a number of different cancer types, some of which currently lack vigorous clinical markers.

Calcitonin receptor gene and breast cancer: quantitative analysis with laser capture microdissection

There is a growing body of evidence indicating that calcitonin (CT) and its receptor (CTR) is involved in cell growth, differentiation and tissue development. Using laser capture microdissection (LCM) and real-time reverse transcription polymerase chain reactions (RT-PCR), we have investigated CTR mRNA expression in 60 primary breast cancers, including 14 pairs of matched cancers and unaffected ductal epithelia from the same patients. Our results demonstrate that CTR mRNA was constantly expressed in normal ductal epithelium and in breast cancer. In the 14 cases where matched samples were available, a decrease in CTR mRNA expression was found in 9 breast cancers (64.3%), an increased CTR expression in 2 cases (14.3%) and no significant change in 3 cases (21.4%). In 60 cases of primary breast cancers, decreased CTR expression was found in 44 (73.3%), increased CTR expression was detected in 10 cases (16.7%) and no change was observed in 6 cases (10%). Decreased CTR expression was found more often in cases with lymph node metastasis (p = 0.0498) and lymphatic invasion (p = 0.0179). Also there was a decreased CTR expression in cases with an extensive intraductal component (p = 0.0543) and a high nuclear grade (p = 0.1934), although this was not statistically significant. Overall, we conclude that CTR mRNA was constantly expressed in unaffected ductal epithelium, whereas decreased CTR mRNA expression was frequently found in breast cancers, particularly in cases with lymph node metastasis and lymphatic invasion. These results suggest that CTR might be of great potential significance in breast cancer progression.

Analysis of human bone sialoprotein in normal and pathological tissues using a monoclonal antibody (BSP 1.2 mab)

Bone sialoprotein (BSP), a phosphorylated and sulphated glycoprotein that is expressed by mineralized connective tissues is also produced in tumors that metastasize to bone. To facilitate studies of BSP expression in normal and pathological human tissues a monoclonal antibody (BSP 1.2 mab) was raised against human bone BSP. BSP 1.2 mab was shown by ELISA assays to recognize the epitope "DEYSY" (amino acids 279-283) that is conserved in mammalian BSP sequences. However, whereas the antibody recognized recombinant BSPs expressed in bacteria, it did not recognize native forms of rat or pig BSP in which the first tyrosine of the DEYSY peptide sequence appears to be modified. Immunostaining of embryonic human tibiae and calvariae with BSP 1.2 mab showed strong reaction in osteoblasts and osteocytes with relatively weak staining of the bone matrix, suggesting that the BSP 1.2 mab epitope is partially masked in the bone matrix. BSP 1.2 mab also stained osteosarcoma cells and normal trophoblastic cells in the placenta in areas of microcrystalline deposits. Cancer cells in primary breast tumors, lymph nodes, and secondary bone metastases from individual patients were stained strongly by BSP 1.2 mab. Although BSP 1.2 mab also stained breast cancer carcinoma cell lines and SaOS2 osteosarcoma cells, biosynthesis of radiolabelled BSP could not be demonstrated in breast cancer cells. Notably, the staining of BSP in the breast cancer cells was diffuse contrasting the punctate staining, typical of secreted proteins, in SaOS2 cells. These studies, therefore, have identified a unique epitope in human BSP recognized by a monoclonal antibody, BSP 1.2 mab, which can be used for the unequivocal identification of BSP in normal and pathological human tissues.

Tissue-specific activity of the proximal human calcitonin receptor promoter is mediated by Sp1 and an epigenetic phenomenon

To identify cis-acting sequences transcriptionally regulating the human calcitonin receptor (hCTR) gene, hCTR promoter/luciferase gene constructs were transiently or stably transfected into hCTR-positive and -negative cell lines. Luciferase assays demonstrated that the proximal hCTR promoter (hCTRP1) was transcriptionally active in all cell lines tested. High-level hCTRP1 activity depended on an 11 bp Sp1/Sp3 binding site. Electrophoretic mobility shift assay showed that this region bound the transcription factors Sp1 and Sp3. We further showed that hCTRP1 was strongly activated by the 11 bp Sp1/Sp3 binding site in hCTRP1/luciferase-, Sp1-transfected Drosophila S2 cells. Bisulphite-mediated sequencing of genomic DNA from hCTR-expressing and -non-expressing cell lines demonstrated that the endogenous hCTRP1 was hypomethylated in all cell lines tested. These results suggest that the hCTRP1 is activated by the tissue-ubiquitous transcription factor Sp1 and that an epigenetic process unrelated to CpG methylation represses its activity in hCTR-negative tissues.

Overexpression of osteopontin is associated with intrahepatic metastasis, early recurrence, and poorer prognosis of surgically resected hepatocellular carcinoma

BACKGROUND

Intrahepatic metastasis via portal vein spread is an important feature and a crucial unfavorable prognostic factor of hepatocellular carcinoma (HCC). To identify the molecular factors for tumor progression, the authors used differential display (DD) to analyze aberrant gene expression in HCC. The goal of the current study was to elucidate the clinicopathologic and prognostic significance of osteopontin (OPN) in HCC progression.

METHODS

OPN mRNA levels, which were increased preferentially in HCC in a DD assay and verified with Northern blotting, were measured in 240 surgically removed, unifocal, primary HCCs using the reverse transcription-polymerase chain reaction at the exponential phase. OPN mRNA expression was correlated with clinicopathologic features, particularly portal vein invasion, early tumor recurrence, and prognosis.

RESULTS

Osteopontin mRNA was overexpressed in 133 tumors (55%). The OPN overexpression was associated closely with alpha-fetoprotein elevation (P = 0.001), p53 mutation (P = 0.021), larger tumors (P = 0.002), high-grade HCC (P < 0.001), late-stage HCC (P < 0.001), early tumor recurrence and/or metastasis (P = 0.003), and a lower 10-year survival rate (P = 0.00013). Multivariate analysis revealed that tumor stage and early tumor recurrence were crucial prognostic factors. In early-stage HCC, which has no vascular invasion and a lower early tumor recurrence than late-stage HCC, OPN mRNA overexpression predicted a higher early recurrence rate (P = 0.003).

CONCLUSIONS

OPN mRNA overexpression was correlated closely with high-grade, late-stage, and early tumor recurrence, which lead to poorer prognosis. Osteopontin overexpression might serve as an unfavorable prognostic factor and a useful marker for predicting early recurrence in early-stage HCC.

Calcitonin receptor gene expression in K562 chronic myelogenous leukemic cells

BACKGROUND: The peptide hormone calcitonin (CT) can significantly effect the proliferation rate of CT receptor (CTR) positive human cancer cells. We wish to identify additional human cancers expressing CTRs and assay the effects of CT on their growth rates and signal transduction pathways. RESULTS: The expression of the human calcitonin receptor (hCTR) gene in the chronic myelogenous leukemia cell line K562 was examined. RT-PCR on total RNA extracted from K562 cells detected the presence of hCTR mRNA. Further analysis demonstrated that multiple hCTR isoforms were present. Incubation of K562 cells with salmon calcitonin (sCT), but not amylin, caused an increase in intracellular levels of cAMP similar to that induced by forskolin treatment. We further demonstrated that butyrate induced erythroid differentiation of K562 cells caused a significant decrease in hCTR mRNA levels. However, phorbol myristate acetate (PMA) induced megakaryocytic differentiation of these cells had no significant effect on hCTR mRNA levels. We demonstrated that exposure to various concentrations of sCT had no effect on the cellular proliferation of K562 cells in vitro. CONCLUSION: Chronic myelogenous k562 cells express multiple CTR isoforms. However, CT does not effect K562 proliferation rates. It is likely that the small increase in intracellular levels of cAMP following CT treatment is not sufficient to interfere with cellular growth.

Solid-phase synthesis of peptide radiopharmaceuticals using Fmoc-N-epsilon-(hynic-Boc)-lysine, a technetium-binding amino acid: application to Tc-99m-labeled salmon calcitonin

Labeling of proteins with metallic radionuclides for use in radiopharmaceuticals involves covalently attaching a bifunctional chelator. In principle, use of smaller peptides allows this chelator to be incorporated during solid-phase peptide synthesis (SPPS) with total site specificity. To realize the advantages of this approach, a lysine-hynic conjugate Fmoc-N-epsilon-(Hynic-Boc)-Lys was synthesized for incorporating the well-known technetium-99m-binding hydrazinonicotinamide ligand into peptides during SPPS. It was used to synthesize a technetium-99m-labeled salmon calcitonin with the hynic-linked amino acid in place of lysine-18. A trifluoroacetate group protected the hynic during alkaline oxidation to the cyclic disulfide and was readily removed by mild acid treatment. The peptide was efficiently labeled (91-98% radiochemical yield) with Tc-99m in the presence of tricine and SnCl(2) with high specific activity (>100 MBq/microg). The product showed good serum stability and specific affinity for human calcitonin receptors. Fmoc-N-epsilon-(Hynic-Boc)-Lys is a highly versatile technetium-binding amino acid for incorporation into peptides during SPPS. This allows total flexibility and control in the site of attachment and is suitable for a combinatorial approach to peptide radiopharmaceuticals.

Transcriptional regulation of osteopontin and the metastatic phenotype: evidence for a Ras-activated enhancer in the human OPN promoter

Elevated osteopontin (OPN) transcription often correlates with increased metastatic potential of transformed cells, and in several model systems OPN--whether produced by the tumor cells or by stromal cells - has been shown to enhance metastatic ability. Sequence elements in the OPN promoter have been identified on the basis of their ability to interact with protein factors associated with the tumorigenic process in one or more cell lineages. One of these is a Ras-activated enhancer (RAE) that binds a protein, the Ras-response factor (RRF), whose ability to form a complex with the RAE is stimulated by Ras signaling in fibroblasts and epithelial cells. Another is the T cell factor-4 binding site, which in the OPN promoter can retard OPN transcription when bound by the Tcf-4 protein. In Rama 37 rat mammary epithelial cells Tcf-4 suppresses OPN transcription and the metastatic phenotype. A third promoter segment consists of two sequences in the -94 to -24 region of the human OPN promoter able to bind several known transcription factors, including Sp1, Myc and Oct-1, which may act synergistically to stimulate OPN transcription in malignant astrocytic cells. Although expression of other genes may also be regulated by these transcription factors, evidence suggests that often OPN alone can stimulate metastasis. In this communication we address two issues: (1) How does OPN facilitate the metastatic phenotype? (2) What mechanisms are responsible for the increase in OPN transcription in metastatic cells?

Tumor angiogenesis of non-small cell lung cancer

Lung cancer is one of the commonest causes of cancer death in developed countries. Recent evidence suggests that angoigenesis is related to poor prognosis in many solid tumors including non-small cell lung cancer (NSCLC). Angiogenesis is regulated by a complex interaction among growth factors and cytokines and influenced by proteolytic enzymes such as plasminogen activators and matrix metalloproteases, expression of adhesion molecules, and distribution of extracellular matrices. Fibroblasts, macrophages, mast cells, and endothelial cells themselves also affect angiogenesis. This review concentrates on angiogenic growth factors including vascular endothelial growth factor, angiopoietins, platelet derived endothelial growth factor, and basic fibroblast growth factor, proteases, adhesion molecules including vascular endothelial cadherin and integrins, osteopontin, and mast cell products in tumor angiogenesis of NSCLC.

Calcitonin receptor isoforms expressed in the developing rat kidney

BACKGROUND

Development in the metanephric-kidney transition period involves the precise expression of paracrine and autocrine events in an ordered spatio-temporal manner. Expression of these molecular events is tightly controlled and includes positive and negative growth factors and cognate receptors within close proximity in developing structures in the expanding renal cortex and medulla. The expression of calcitonin receptor (CTR) isoforms C1a and C1b in this context has not previously been described. Our current study also explored the relationship between the expression of CTR isoforms and amylin binding sites.

METHODS

Techniques included immunohistochemistry with novel antibodies that detect CTR isoforms, real time PCR for the quantification of CTR isoforms, Western blot and in vitro autoradiography, on tissues from embryo day 18 to postnatal day 30.

RESULTS

The CTR C1a isoform is expressed in the ureteric ducts of the metanephros and both isoforms are expressed in the developing distal convoluted tubules, ascending limbs of the loop of Henle and collecting ducts in the postnatal rat kidney. There was a 60-fold excess of C1a versus C1b isoforms. An apparent molecular weight of 63 kD was found. In vitro autoradiography demonstrated that while amylin binding sites were predominantly in the cortex, CTR expression was largely localized in the medulla in an earlier event, followed by cortical expression.

CONCLUSIONS

CTR C1a protein expression has been identified in the ureteric ducts in the metanephros and both isoforms expressed in the distal portions of the developing nephrons and collecting ducts. Since amylin binding sites have been localized on the proximal tubules of the cortex, it is unlikely that amylin receptors can be represented by modification of CTR affinity with receptor activity modifying proteins in the kidney.

Ontogeny of calcitonin receptor mRNA and protein in the developing central nervous system of the rat

In this study, the expression of receptors for calcitonin (CTR), the CTR C1a and C1b isoforms, was investigated during development of the fetal rat central nervous system (CNS) by using in situ hybridization and immunohistochemistry. Coincident expression with both techniques was evident. Immunohistochemical evidence for the expression of the C1a isoform alone was found. Expression was first observed at embryonic day 12/13 (E12/E13) within and adjacent to the ventricular zones known to include primary matrices of proliferation, in regions of the preoptic area, anterior and posterior hypothalamus, anterior and posterior pons, medulla, and spinal cord. At later times, with the decline in the density of immunoreactivity at these loci (E15), expression in primary matrices was found later at distinct loci within the ventricular zones of cerebellum (E17), and at E19, the tectum, lateral ventricle, and cortical subplate. By E19, the density of staining had increased and was widespread throughout the expanding CNS. In the rostral domains, moderate to high density was found in the external plexiform layer; the medial preoptic area and nucleus; the ventromedial, dorsomedial, and arcuate hypothalamic nuclei; and the lateral and posterior hypothalamic areas. In the midbrain, similar levels of expression were noted in the central nucleus of raphe; the deep mesencephalic, dorsal raphe, and laterodorsal tegmental nuclei; and the ventral periaqueductal gray. In the pons, positive loci included the locus coeruleus and the gigantocellular and pontine reticular nuclei. In the medulla, high expression was evident in the gigantocellular, intermediate, magnocellular, and medullary reticular, spinal trigeminal and cuneate nuclei; and the nucleus tractus solitarius. In the spinal cord, moderate to high density of staining was found in the ventral, dorsal, and lateral horns, and in the ventral, dorsal, and cuneate funiculi. On the other hand, transitory expression was found in the diagonal band, bed nucleus of the stria terminalis, amygdala, and the lateral mamillary and anterobasal nuclei of the hypothalamus. These studies indicate a role for CTR in the activation of some premigratory neuroblasts in the CNS as well as a possible role later in an undefined function associated with mature neurons of particular nuclei.

Extracellular matrix components in breast carcinomas

A malignant process interferes with the normal 'programme' of extracellular matrix biosynthesis and can modify extensively the structure and composition of the matrix. This effect appears to be attributable to several processes such as direct production of some selected matrix macromolecules by malignant cells or indirectly by the production of factors by malignant cells interfering with the regulation of normal matrix production. Other possibilities may also exist, such as the direct action of an environmental carcinogen on otherwise normal mesenchymal cells. The result is a more or less profound modification of tissue structure and composition with possible feedback effects on the malignant process. Some examples will be discussed such as elastin production by some tumours as well as the biosynthesis of some other selected matrix macromolecules as tenascin and osteopontin by breast tumours. Although the detailed mechanisms of these specific matrix productions is not yet completely elucidated, the rapidly increasing knowledge on the regulation of specific matrix production process and deranged matrix production might represent a new area of crosstalk between cancer research and matrix biology.

Differential gene expression of TGF-beta family members and osteopontin in breast tumor tissue: analysis by real-time quantitative PCR

Several cytokines including members of the transforming growth factor-beta (TGF-beta) and tumor necrosis factor (TNF) families have been implicated in the homing mechanism of breast cancer metastasis. We hypothesize that primary breast tumor tissues differentially express modulators of bone cell function and that this expression pattern contributes to their aggressive and metastatic potential and to their capacity to establish and grow in bone. We, therefore, examined the gene expression pattern of the TGF-beta family members (inhibin/activin betaA subunit (activin betaA), inhibin alpha subunit, and bone morphogenetic protein-2 (BMP-2)), the TNF family members (receptor activator of NF-KB ligand (RANKL) and osteoprotegerin (OPG)), and osteopontin (OPN) in normal, non-invasive, invasive, and metastatic human breast cancer specimens. The mRNA transcript levels of these genes were quantified by reverse transcription (RT) and fluorescent-based kinetic PCR in 18 normal breast tissues, five ductal carcinoma in situ (DCIS). 24 primary breast tumor tissue, and five distant metastases. The mRNA transcript level of each gene was normalized to the amount of beta-actin present in the samples. We observed differential gene expression of the selected TGF-beta family members as well as OPN in breast cancer progression. The average gene expression of the putative tumor suppressor, inhibin alpha, did not significantly change in any of the tumor tissues examined compared to normal breast tissue. The mRNA level of BMP-2, a protein with anti-proliferative effects in breast cancer cell lines and involved in bone formation, significantly decreased in non-invasive, invasive, and liver metastatic breast tumor tissue compared to normal breast tissue. The gene expression of activin betaA, a protein involved in cell proliferation and osteoclast induction, increased in invasive and bone metastatic tumor tissue compared to normal breast tissue. The mRNA level of OPN, a bone matrix protein associated with enhanced malignancy, increased in non-invasive, invasive, and liver and bone metastatic breast tumor tissue compared to normal breast tissue. In contrast, the average gene expressions of the TNF family members, RANKL and OPG, proteins involved in the regulation of osteoclastogenesis, were only slightly if at all changed in the different stage breast tumor tissues. These results suggest that differential gene expression of bone-related proteins, especially OPN, activin betaA, and BMP-2, by primary breast tumor tissues may play a significant role in the invasiveness and metastatic potential of breast cancer.

Molecular pathology of tumor metastasis. II. Molecular staging and differential diagnosis

Molecular Pathology of Tumor Metastasis With the development of non-invasive methods, diagnosis of metastasis from various solid malignancies has become a routine task for diagnostic pathology. However, the differential diagnosis between primary and metastatic cancers and the precise identification of various metastatic cancer types requires the coordinated use of various morphological (light- and electron microscopic-), immunological and molecular techniques. The detection of the lymphatic spread of the primary tumor may now based on the sentinel lymph node technology while the identification of the hematogenous progression may be based on the analysis of the peripheral blood and the bone marrow. More and more frequently these techniques employ highly sensitive immunological and molecular techniques. Accordingly, clinical staging is now confronted with the results of molecular staging, where the only techniques which are able to detect cancer cells are immunocytochemistry or nucleic acid-based methodology. Although several clinical studies have provided evidences for the impact of the immunocytochemistry-based identification of micrometastases on the survival of patients with various type of cancers, none of these methods have become part of standard diagnostic protocols. Although more sensitive molecular techniques are being introduced to identify micrometastasis, their clinical significance is yet unknown. Multicentric clinical trials are now warranted to establish the clinical impact of molecular staging in various cancer types. Without the integration of these methods into the prognostic/predictive pathological protocols it is difficult to envision significant improvement in the results of cancer therapy.

Bone sialoprotein, bone morphogenetic protein 6 and thymidine phosphorylase expression in localized human prostatic adenocarcinoma as predictors of clinical outcome: a clinicopathological and immunohistochemical study of 43 cases

PURPOSE

Skeletal metastases are the hallmark of advanced prostate cancer and recurrence after local surgery is common. Currently to our knowledge no biological markers predict the risk of disease progression in individuals with localized prostate cancer. In a search for predictive markers we evaluated the expression of bone sialoprotein and bone morphogenetic protein 6, 2 bone related proteins, and the angiogenic factor thymidine phosphorylase.

MATERIALS AND METHODS

The study population included 43 men who presented with localized prostate cancer treated with radical prostatectomy. Bone sialoprotein, bone morphogenetic protein 6 and thymidine phosphorylase expression was assessed by immunohistochemical testing. Results were analyzed in relation to pathological disease stage, Gleason score and clinical outcome. Clinical followup was 4.3 to 11.4 years after surgery (median 7.9).

RESULTS

Disease did not progress in 17 of the 43 cases, while recurrence and/or metastasis developed in the other 26 at a median of 6.5 and 6.9 years, respectively. Bone sialoprotein and bone morphogenetic protein 6 expression detected in 28 (65%) and 29 (67%) of the 43 samples, respectively, was significantly associated (p = 0.0001). Thymidine phosphorylase detected in 26 samples (60%) was not related to bone sialoprotein and/or bone morphogenetic protein 6 positivity. Bone sialoprotein and/or bone morphogenetic protein 6 expression correlated with bone metastasis, while thymidine phosphorylase expression was related to local recurrence (p = 0.002 and/or 0.007, and 0.00007, respectively). On multivariate analysis only the correlation of thymidine phosphorylase expression with recurrence remained statistically significant (p = 0.002). Co-expression of the 3 markers was observed in the samples of 10 of the 11 patients (90%) with bone metastases and only in 5 of the 17 (29%) who were disease-free.

CONCLUSIONS

This study indicates that the expression of bone sialoprotein, bone morphogenetic protein 6 and thymidine phosphorylase determined at a clinically early stage of disease by a simple immunohistochemical technique would enable subgroups of patients to be identified that are at different risks of bone metastasis or recurrence. Detection of such markers would provide additional prognostic information that would be useful for patients with intermediate or low Gleason score or stage disease. These patients would benefit from a more adapted clinical follow-up.

Differential osteopontin expression in lung cancer

Osteopontin (OPN) is a phosphorylated glycoprotein with diverse functions including cancer development, progression and metastasis. Its expression is induced by a variety of stimuli such as TNF-alpha and Ras proto-oncogene. However, differential OPN expression and its regulation in each histologic type of lung cancer are not well established. In this study, we assessed expression of OPN in lung cancer tissues with immunohistochemical analysis. OPN was predominantly expressed in tumor cells of non-small cell lung cancer (NSCLC) tissues: 11 of 16 cases (68.8%) of squamous cell carcinoma (SCC), five of 24 cases (20.8%) of adenocarcinoma (AD), but only two of 18 cases (11%) of small cell lung cancer (SCLC). Expectedly, OPN was principally expressed in NSCLC cell lines (H322 cells and HL460 cells) but not in SCLC cell line (H69 cells) by Western blotting and Northern blotting. Interestingly, Ras-p21 was specifically co-expressed with OPN staining in eight of eight cases with SCC (100%), whereas it was demonstrated in three of ten cases (30%) with AD and only one of 18 cases (5%) with SCLC. Collectively, these results suggest that OPN is mainly expressed in NSCLC, especially among SCC. OPN expression may be tightly regulated by Ras oncogene, and its concomitant induction with Ras activation may play a crucial role in the development of SCC.

The role of osteopontin in breast cancer: clinical and experimental studies

Osteopontin (OPN) is a secreted, integrin-binding protein which has been implicated in cancer, as well as other pathologies and some aspects of normal development. Here we focus on the role of OPN in breast cancer. We describe studies that have shown that OPN plays a role in normal mammary gland development as well as in progression of breast cancer. We also summarize studies that have shown that OPN can play a functional role in malignancy of breast cancer. At least some of these effects are mediated by specific cell surface integrins (alpha(v)beta3 vs. alpha(v)beta1 and alpha(v)beta5) and lead to increased cell migration, activation of growth factor/receptor pathways (e.g. HGF and EGF), and increased proteolytic enzyme activity (e.g. uPA). We also summarize clinical studies that show that OPN levels in tumors and blood are elevated in women with metastatic breast cancer and may offer promise as prognostic markers in breast cancer.

Role of osteopontin in cellular signaling and toxicant injury

Osteopontin (OPN) is a glycosylated phosphoprotein found in all body fluids and in the proteinaceous matrix of mineralized tissues. It can function both as a cell attachment protein and as a cytokine, delivering signals to cells via a number of receptors including several integrins and CD44. Expression of OPN is enhanced by a variety of toxicants, especially those that activate protein kinase C. In its capacity as a signaling molecule, OPN can modify gene expression and promote the migration of monocytes/macrophages up an OPN gradient. It has both inflammatory and anti-inflammatory actions. Some experiments suggest that it may inhibit apoptosis, possibly contributing to the survival of cells in response to toxicant injury. Elevated OPN expression often correlates with malignancy and has been shown to enhance the tumorigenic and/or metastatic phenotype of the cancer cell. Recent studies have revealed that OPN plays critical roles in bone remodeling and cell-mediated immunity.

Chitosan accelerates the production of osteopontin from polymorphonuclear leukocytes

Chitosan is a copolymer of beta(1 --> 4) glucosamine and N-acetyl-D-glucosamine, which accelerates the infiltration of polymorphonuclear leukocytes (PMN) in the early phase of wound healing. In the granulation tissue treated with chitosan in canine experimental wound, osteopontin (OPN) was strongly positive in PMN immunohistochemically. OPN is a glycosylated phosphoprotein and promotes the attachment or spread of a variety of cell types. In addition, OPN may play a role in granulomatous inflammation. Production of OPN in PMN was therefore investigated in vitro using human PMN in this study. PMN stimulated with granulocyte-colony stimulating factor (G-CSF) and chitosan accumulated OPN mRNA, and released OPN into their culture supernatants. These findings suggest that OPN is synthesized by migrating PMN which plays the novel role of regulating the evolution of wound healing with chitosan treatment at the early phase of healing.

Expression of bone sialoprotein and osteopontin in breast cancer bone metastases

Bone sialoprotein (BSP) and osteopontin (OPN) are prominent, mineral-associated proteins in the extracellular matrix of bone that have been implicated in the metastatic activity of cancer cells. The expression of BSP, which is normally restricted to mineralizing tissues, has been observed in cancers with a high propensity for forming bone metastases. To investigate the relationship between BSP expression and the formation of bone metastases we have conducted an initial study of the expression of BSP in 10 intraductal breast carcinoma bone metastases using immunostaining and in situ hybridization, and compared the expression with OPN. The metastases were characterized by the infiltration of tumour cells into bone with extensive bone resorption evident. Moderate to strong staining for BSP was observed in all (100%) carcinomas, which also expressed BSP mRNA as determined by in situ hybridization. Variable staining for BSP was also observed in the mineralized bone and expression of BSP mRNA could be observed in osteoblastic cells on the bone surface and in some osteocytes at sites of bone remodelling. Contrary to a previous report, BSP expression could be demonstrated by PCR in three breast cancer cell lines, MCF-7, T47-D and MDA-MB-231. Moreover, in sub-cutaneous tumours formed by MDA-MB-231 breast cancer cells injected into athymic mice, higher immunostaining for BSP was seen in large ulcerating tumours in which mineral deposits were formed. In contrast to BSP, staining for OPN in bone metastases was generally restricted to the interface between tumor cells and bone surface of the carcinomas. While OPN staining was also observed in the cytoplasm of osteoclasts, which showed strong hybridization to a digoxygenin-labelled OPN cRNA probe, expression of OPN was not clearly detectable in the tumour cells. These studies provide the first demonstration of BSP expression by tumour cells in bone metastases and support the concept that BSP may have a role in targeting metastatic cells to bone. Expression of OPN in bone metastases appears to be related to increased bone resorptive activity by osteoclasts.

Molecular pathology of tumor metastasis. I. Predictive pathology

Millennium reviews of oncology agreed that the last century produced major developments mainly in the management of the primary tumor, but despite all of these results, cancer still remains among the leading causes of death due to the failure of clinical management of disseminated disease. This failure is primarily due to the lack of detailed information on the molecular mechanisms of tumor metastasis. Therefore, one of the hottest fields in experimental oncology is metastasis research, which provides more and more information about the molecular mechanisms. However, this information is fragmented and is not yet exploited in clinical practice. A new field of diagnostic pathology recently emerged, which translates basic research data to diagnostic practice to provide clinically relevant information on the biological potential (in this case metastatic potential) of the malignant tumors. Since tumor cell-extracellular matrix interactions are key features of tumor dissemination, expression of genes responsible for them can define the metastatic potential of malignant tumors. This review summarizes our recent knowledge on the metastatic geno- and phenotype of major human solid tumors: lung, colon, breast, prostate cancers and malignant melanoma.