Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0278488 (metastatic breast cancer)
 7,812 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The serine protease urinary plasminogen activator or urokinase (uPA), produced in abundance by many malignancies, plays a key role in tumor cell invasion and metastasis. uPA is localized within the malignant cell milieu via its cell surface receptor [uPA receptor (uPAR)], which is expressed by tumor and tumor-associated cells. In the present study, we have used a syngeneic model of rat breast cancer to directly evaluate the role of uPAR as a diagnostic and therapeutic target in metastatic breast cancer. A polyclonal antibody against the ligand-binding NH(2)-terminal domain of rat uPAR (ruPAR) was developed. This antibody recognizes ruPAR by both immunofluorescence and Western blot analysis. Recombinant ruPAR and ruPAR IgG displaced the binding of (125)I-labeled ruPAR IgG to rat prostate cancer cells (Dunning R3227 Mat Ly Lu) and breast cancer cells (Mat B-III) overexpressing ruPAR (Mat B-III-uPAR). ruPAR IgG also blocked the invasive capacity of these tumor cells in a dose-dependent manner. Mat B-III-uPAR cells were inoculated s.c. into the mammary fat pad of syngeneic female Fischer rats. On day 10 after tumor cell inoculation, animals were injected with (125)I-labeled preimmune or ruPAR IgG and then sacrificed at timed intervals. Maximum (125)I uptake was observed in primary tumors and in tissues commonly affected by tumor metastases (liver, spleen, lungs, and lymph nodes) at 12 h. Injection of (125)I-labeled preimmune or ruPAR IgG into normal non-tumor-bearing animals resulted in minimal basal levels of uPAR expression and established the specificity of the ruPAR IgG. Similar results were obtained by Northern blot and PCR analysis of mRNA isolated from tissues of normal and tumor-bearing animals. To evaluate the effectiveness of this antibody in tumor progression, ruPAR IgG (50-100 microg/day) was injected s.c. for 7 days (day 1-7) at the site of tumor cell inoculation (mammary fat pad), and animals were sacrificed at various time points for evaluation of tumor growth and metastases. Animals receiving ruPAR IgG showed a marked decrease in tumor growth and metastases as compared with control tumor-bearing animals receiving the same dose of preimmune rabbit IgG. Histological analysis of experimental primary tumors showed marked tumor necrosis that was due to increased tumor cell apoptosis as determined by terminal deoxynucleotidyl transferase-mediated nick end labeling assay. Together, these studies demonstrate the ability of anti-uPAR antibody to decrease tumor volume and detect the presence of microscopic occult tumor metastases in malignancies where uPA/uPAR play a key role in tumor progression.
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PMID:Urokinase receptor antibody can reduce tumor volume and detect the presence of occult tumor metastases in vivo. 1195 2

Breast cancer is the most common malignancy afflicting Western women today and is responsible for many deaths due to metastatic disease. Upregulation of the plasminogen-activation system (PAS) has been shown to correlate with poor prognosis in metastatic breast cancer and targeting this system represents an attractive strategy for the development of anti-metastasis prophylactic drugs. Two promising classes of PAS-targeting agents are inhibitors of the serine protease activity of urokinase plasminogen activator (uPA) and antagonists of the interaction of uPA with its cell surface receptor (uPAR). This review begins with a brief overview of the role of PAS in cancer metastasis before describing in detail a subset of the small molecules and peptides from the patent literature that target either uPA activity or uPA/uPAR interactions for use as anti-metastasis drugs.
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PMID:Peptides and small molecules targeting the plasminogen activation system: towards prophylactic anti-metastasis drugs for breast cancer. 1828 19

Metastatic breast cancer shows extreme tropism for the bone microenvironment, leading to the establishment of osteolytic metastases. Perpetuation of tumor-induced osteolysis requires a continuous supply of osteoclast precursors migrating into the bone microenvironment that can subsequently differentiate into mature osteoclasts and resorb bone. Thus, identification and subsequent targeting of chemoattractants of osteoclast precursors that are up-regulated at the tumor-bone interface represents a potential avenue to interrupt osteolysis. We report that cathepsin G, a serine protease, plays a vital role in the bone microenvironment by modulating tumor-stromal interaction in a manner that favors tumor establishment and regulates chemotaxis of monocytes, a subset of which has the potential to differentiate into osteoclasts. Our data show that cathepsin G-induced chemotaxis of monocytes is mediated by proteolytic activation of protease-activated receptor-1 (PAR-1). Attenuation of PAR-1 activation abrogates cathepsin G-mediated induction of monocyte chemotaxis. We also show that in vivo inhibition of cathepsin G reduces the number of CD11b(+) osteoclast precursors and mature osteoclasts at the tumor-bone interface. Together, these data suggest that therapeutic targeting of both PAR-1 signaling in osteoclast precursors as well as cathepsin G at the tumor-bone interface has the potential to reduce osteolysis by inhibiting the recruitment, differentiation, and activation of osteoclast precursors.
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PMID:Cathepsin G recruits osteoclast precursors via proteolytic activation of protease-activated receptor-1. 1929 92

The serine protease urokinase (uPA, urokinase-type plasminogen activator) is over-expressed in certain tumors and is considered to be the strongest single indicator of poor prognosis in patients with metastatic breast cancer. In this article, we describe the isolation and affinity maturation of a fully human recombinant antibody (termed DS2), specific to the human uPA and capable of inhibiting its enzymatic activity with an IC(50) value in the low nanomolar range. The novel antibody cross-reacts with murine uPA. It was expressed both as scFv fragment and in IgG format, allowing a systematic comparative immunofluorescence (IF) analysis of the uPA expression patterns in a large panel of human und murine tumors and of normal human tissues. Although uPA was strongly expressed in virtually all tumor specimens tested, it exhibited only a weak expression in certain normal tissues (mainly in the colon, lung, spleen and bone marrow). IgG(DS2) was not able to inhibit cancer growth in immunocompromised mice bearing subcutaneous human MDA-MB-231 or DoHH-2 tumors. However, an ex vivo IF analysis confirmed the ability of the DS2 antibody to preferentially localize at the tumor site compared with normal organs. Collectively, these data suggest that uPA blocking antibodies may not be indicated for cancer growth inhibition strategies, but may serve as valuable tools for the implementation of pharmacodelivery strategies against a variety of different tumors.
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PMID:Isolation and characterization of an inhibitory human monoclonal antibody specific to the urokinase-type plasminogen activator, uPA. 2008 40