Plg-R Expression in Human Breast Cancer Tissues.

The plasminogen activation system regulates the activity of the serine protease, plasmin. The role of plasminogen receptors in cancer progression is being increasingly appreciated as key players in modulation of the tumor microenvironment. The interaction of plasminogen with cells to promote plasminogen activation requires the presence of proteins exposing C-terminal lysines on the cell surface.

Identification of the integrin-binding site on coagulation factor VIIa required for proangiogenic PAR2 signaling.

The tissue factor (TF) pathway serves both hemostasis and cell signaling, but how cells control these divergent functions of TF remains incompletely understood. TF is the receptor and scaffold of coagulation proteases cleaving protease-activated receptor 2 (PAR2) that plays pivotal roles in angiogenesis and tumor development. Here we demonstrate that coagulation factor VIIa (FVIIa) elicits TF cytoplasmic domain-dependent proangiogenic cell signaling independent of the alternative PAR2 activator matriptase.

Targeting cancer-specific glycans by cyclic peptide lectinomimics.

The transformation from normal to malignant phenotype in human cancers is associated with aberrant cell-surface glycosylation. Thus, targeting glycosylation changes in cancer is likely to provide not only better insight into the roles of carbohydrates in biological systems, but also facilitate the development of new molecular probes for bioanalytical and biomedical applications. In the reported study, we have synthesized lectinomimics based on odorranalectin 1; the smallest lectin-like cyclic peptide isolated from the frog Odorrana grahami skin, and assessed the ability of these peptides to bind specific carbohydrates on molecular and cellular levels.

New insights into the role of Plg-RKT in macrophage recruitment.

Plasminogen (PLG) is the zymogen of plasmin, the major enzyme that degrades fibrin clots. In addition to its binding and activation on fibrin clots, PLG also specifically interacts with cell surfaces where it is more efficiently activated by PLG activators, compared with the reaction in solution. This results in association of the broad-spectrum proteolytic activity of plasmin with cell surfaces that functions to promote cell migration.

Combining cellular and gene therapy approaches for treatment of intracranial tumors.

New treatments are needed for brain metastasis, which is associated with high morbidity and mortality. Two novel cellular and gene therapy modalities were evaluated in xenograft models for human breast cancer. The individual and especially the combined treatments with alloreactive cytotoxic T lymphocytes and replicating retroviral vectors coding for prodrug activating enzymes followed later with nontoxic prodrug demonstrated efficacy without off-target effects.

Local adipocytes enable estrogen-dependent breast cancer growth: Role of leptin and aromatase.

The importance of the microenvironment in breast cancer growth and progression is becoming increasingly clear. Adipocytes are abundant in the mammary microenvironment, and recent studies show that adipocytes produce endocrine, inflammatory, and angiogenic factors that have tremendous potential to affect adjacent breast cancer cells. Yet, the extent to which local adipocyte function contributes to the pathogenesis of breast cancer is largely unexplored.

Endothelial protein C receptor function in murine and human breast cancer development.

Several markers identify cancer stem cell-like populations, but little is known about the functional roles of stem cell surface receptors in tumor progression. Here, we show that the endothelial protein C receptor (EPCR), a stem cell marker in hematopoietic, neuronal and epithelial cells, is crucial for breast cancer growth in the orthotopic microenvironment of the mammary gland. Mice with a hypomorphic allele of EPCR show reduced tumor growth in the PyMT-model of spontaneous breast cancer development and deletion of EPCR in established PyMT tumor cells significantly attenuates transplanted tumor take and growth.

Cooperation of tissue factor cytoplasmic domain and PAR2 signaling in breast cancer development.

Constitutive expression of tissue factor (TF) by cancer cells triggers local activation of the coagulation cascade and promotes breast cancer progression through cell signaling involving protease activated receptor (PAR)2. In human breast cancer, TF and PAR2 are up-regulated and TF cytoplasmic domain phosphorylation is correlated with relapse. Here we show that cancer cell PAR2 signaling promotes angiogenesis independent of PAR2 phosphorylation at the recognized β-arrestin recruitment site.

Hyaluronan inhibits postchemotherapy tumor regrowth in a colon carcinoma xenograft model.

Bone marrow hypoplasia and pancytopenia are among the most undesirable sequelae of chemotherapy for the treatment of cancer. We recently showed that hyaluronan (HA) facilitates hematopoietic recovery in tumor-free animals receiving chemotherapeutic agents. However, following a chemotherapeutic regimen in tumor-bearing animals, it is possible that residual tumor cells might respond to systemic injections of HA.

FAPP2 gene downregulation increases tumor cell sensitivity to Fas-induced apoptosis.

The gene for phosphatidylinositol-4-phosphate adaptor-2 (FAPP2) encodes a cytoplasmic lipid transferase with a plekstrin homology domain that has been implicated in vesicle maturation and transport from trans-Golgi to the plasma membrane. The introduction of ribozymes targeting the FAPP2 gene in colon carcinoma cells induced their apoptosis in the presence of Fas agonistic antibody. Furthermore, by quantitative PCR we showed that a siRNA specific to FAPP2, but not a randomized siRNA control, reduced FAPP2 gene expression in tumor cells.

siRNA Down-regulation of the PATZ1 Gene in Human Glioma Cells Increases Their Sensitivity to Apoptotic Stimuli.

The PATZ1 gene encodes a transcription factor that belongs to the BTB/POZ group of transcriptional regulators and has been implicated as a transcriptional repressor. We cloned cDNA from glioma cell lines and found they expressed transcript variant 2 of PATZ1. We designed a specific siRNA against PATZ1 and showed that this siRNA, but not a control randomized siRNA, reduced PATZ1 expression in glioma cells as determined by quantitative PCR.

Protease-activated receptor (PAR) 2, but not PAR1, signaling promotes the development of mammary adenocarcinoma in polyoma middle T mice.

The G protein-coupled protease-activated receptors (PAR) are key signaling components for proteases in vascular biology and tumor progression. To address the contributions of PAR1 and PAR2 to breast cancer development, we established cohorts of mouse mammary tumor virus-polyoma middle T (PyMT) PAR1(-/-) and PAR2(-/-) mice, considering that the PyMT model recapitulates aspects of human disease. Appearance of palpable tumors, tumor expansion, and metastasis was indistinguishable between wild-type and PAR1(-/-) mice.

Inhibition of tissue factor signaling suppresses tumor growth.

Coagulation activation by tissue factor (TF) is implicated in cancer progression, cancer-associated thrombosis and metastasis. The role of direct TF signaling pathways in cancer, however, remains incompletely understood. Here we address how TF contributes to primary tumor growth by using a unique pair of isotype-matched antibodies that inhibit either coagulation (monoclonal antibody [Mab]-5G9) or direct signaling (Mab-10H10).

Akt plays an important role in breast cancer cell chemotaxis to CXCL12.

The chemokine receptor CXCR4 is functionally expressed on the cell surface of various cancer cells, and plays a role in cell proliferation and migration of these cells. Specifically, in breast cancer cells the CXCR4/CXCL12 axis has been implicated in cell migration in vitro and in metastasis in vivo, but the underlying signaling mechanisms are incompletely understood. The xenograft-derived MDA-MB-231 breast cancer cell line (231mfp), which was shown previously to grow more aggressively than the parent cells, showed increased CXCR4 expression at the mRNA, total protein and cell surface expression level.

Role of protease activated receptor 1 and 2 signaling in hypoxia-induced angiogenesis.

Objective: Tissue factor (TF) initiates coagulation and indirectly triggers thrombin-dependent protease activated receptor (PAR) signaling. The TF-VIIa complex also directly cleaves PAR2 and promotes angiogenesis in vitro in TF cytoplasmic domain-deleted (TF(deltaCT)) mice. Here we address the effect of PAR1 and PAR2 deficiency on angiogenesis in vivo.

Disulfide isomerization switches tissue factor from coagulation to cell signaling.

Cell-surface tissue factor (TF) binds the serine protease factor VIIa to activate coagulation or, alternatively, to trigger signaling through the G protein-coupled, protease-activated receptor 2 (PAR2) relevant to inflammation and angiogenesis. Here we demonstrate that TF.VIIa-mediated coagulation and cell signaling involve distinct cellular pools of TF.

Breaking the one antibody-one target axiom.

Studies at the interface of chemistry and biology have allowed us to develop an immunotherapeutic approach called chemically programmed antibodies (cpAbs), which combines the merits of traditional small-molecule drug design with immunotherapy. In this approach, a catalytic antibody catalyzes the covalent conjugation of a small molecule or peptide to the active site of the antibody, effectively recruiting the binding specificity of the conjugated molecule to the antibody. In essence, this technology provides the tools for breaking the "one antibody-one target axiom" of immunochemistry.

Thrombin generation and the pathogenesis of cancer.

Advanced cancer is associated with a hypercoagulable state that is triggered by tissue factor (TF). TF-initiated thrombin generation is crucial for metastasis through fibrin and platelet deposition, as well as thrombin-dependent protease-activated receptor (PAR) 1 signaling. Surprisingly, PAR2, which is not cleaved by thrombin, appears to cosignal with PAR1 to elicit thrombin effects in metastatic tumor cells.

Protease-activated receptor-2 regulates vascular endothelial growth factor expression in MDA-MB-231 cells via MAPK pathways.

Protease-activated receptor 2 (PAR2) is a G-protein coupled receptor that is cleaved and activated by serine proteases including the coagulation protease factor VIIa (FVIIa). There is evidence that PAR2 function contributes to angiogenesis, but the mechanisms involved are poorly defined. Here we show that PAR2 activation in human breast cancer cells leads to the upregulation of vascular endothelial growth factor (VEGF).

Estrogen induces lung metastasis through a host compartment-specific response.

Direct proliferative effects of estrogen (E(2)) on estrogen receptor-positive tumors are well documented; however, the potential for E(2) to mediate effects selective for the host (i.e., angiogenesis, vascular permeability, or stromal effects), which influence tumor growth and/or metastasis, has received less attention.

Plasminogen activation/plasmin in rheumatoid arthritis: matrix degradation and more.

Rheumatoid arthritis (RA) is one of the most common and most debilitating joint diseases, producing high personal, social, and economic costs.(1,2) Patients with RA suffer pain and functional losses, often followed by disability and premature death. Although the etiology of RA is unknown, substantial efforts have been directed toward studying the transition of the joint from normal to diseased.

Breast cancer cell lines grown in vivo: what goes in isn't always the same as what comes out.

Human cell lines constitute powerful model systems for the in vitro and in vivo analysis of cancer. Cancer lines that are invasive in culture often form tumors and metastases in immune deficient mice. It is generally assumed that, in such cases, the principal population of cancer cells in culture corresponds to the tumor-forming cells in vivo.

Carcinoma and stromal enzyme activity profiles associated with breast tumor growth in vivo.

Cancer research depends on the use of human cell lines for both the in vitro (culture) and in vivo (xenograft) analysis of tumor progression and treatment. However, the extent to which cultured preparations of human cancer lines display similar properties in vivo, where important host factors may influence tumor biology, remains unclear. Here, we address this question by conducting a functional proteomic analysis of the human breast cancer line MDA-MB-231 grown in culture and as orthotopic xenograft tumors in the mammary fad pad of immunodeficient mice.