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Fluorescence-based Monitoring of PAD4 Activity via a Pro-fluorescence Substrate Analog
Published on: November 5, 2014
uPAR mediates anticancer activity of PEDF
Crispin R Dass1, Peter F M Choong
1Department of Orthopaedics, St. Vincent's Hospital Melbourne, University of Melbourne, Australia. cris.dass@yahoo.com
Abstract:
Osteosarcoma (OS) is a cancer which afflicts the bone, ending in usually fatal lung metastasis mainly in teenagers and adolescents. We have recently shown that PEDF is one biological that has multiple anti-OS activity. In parallel, we have also shown using rodent cells, the beneficial effects of downregulation of uPAR against OS. Here, we provide further proof of such effects of uPAR downregulation using human OS cells and combine this with PEDF treatment. We describe the involvement of uPAR with activity of PEDF. In silico, PEDF did not bind to uPA and thus did not attenuate its activity. In the presence of exogenous PEDF, both uPA, its receptor and FAK localize intracellularly. Blocking of uPA and uPAR on the cell surface increased the binding of PEDF, whether endogenous or exogenous. In clinical specimens of OS, there was mutually exclusive expression of PEDF and uPAR at the growing edge of the tumor. Incubation of cells with PEDF and a uPAR antibody led to an increased reduction in invasion of cells through Matrigel, and a heightened apoptotic signal. In vivo, treatment of human OS cells with both PEDF and uPAR DNAzyme resulted in greater primary tumor growth, pulmonary metastasis inhibition and decreased osteolysis. Areas of necrosis were noted in the PEDF-administered group of animals. This study shows an association between two very important systems involved in tumor progression and highlights the possibility that a combined approach of PEDF exposure and uPAR knockdown may lead to a better targeted outcome against OS.
Insights
Pigment Epithelium-Derived Factor (PEDF) and urokinase-type Plasminogen Activator Receptor (uPAR) downregulation show combined efficacy against osteosarcoma (OS). Targeting both PEDF and uPAR may offer a novel therapeutic strategy for this bone cancer.
Area of Science:
- Oncology
- Molecular Biology
- Biochemistry
Background:
- Osteosarcoma (OS) is a primary bone cancer predominantly affecting adolescents and young adults, characterized by high rates of fatal lung metastasis.
- Pigment Epithelium-Derived Factor (PEDF) has demonstrated multiple anti-OS activities, while urokinase-type Plasminogen Activator Receptor (uPAR) downregulation shows beneficial effects in rodent OS models.
Purpose of the Study:
- To investigate the synergistic effects of PEDF treatment and uPAR downregulation in human osteosarcoma cells.
- To elucidate the molecular mechanisms underlying the interaction between PEDF and the uPAR system in OS progression.
Main Methods:
- In silico analysis of PEDF binding to uPA.
- Cell-based assays using human OS cells treated with PEDF and/or uPAR inhibitors (antibody, DNAzyme).
- Analysis of clinical OS specimens for PEDF and uPAR expression.
- In vivo studies in animal models to assess tumor growth, metastasis, and osteolysis.
Main Results:
- PEDF did not directly inhibit uPA activity but influenced the intracellular localization of uPA, uPAR, and FAK in OS cells.
- Blocking cell surface uPA and uPAR enhanced PEDF binding.
- Clinical OS samples showed mutually exclusive expression of PEDF and uPAR at the tumor margin.
- Combined PEDF and uPAR targeting significantly reduced OS cell invasion, increased apoptosis, inhibited primary tumor growth and pulmonary metastasis, and decreased osteolysis in vivo.
Conclusions:
- A combined therapeutic approach involving PEDF and uPAR knockdown demonstrates significant anti-osteosarcoma effects.
- The study reveals a complex interplay between PEDF and the uPAR system in osteosarcoma progression.
- Targeting both PEDF and uPAR represents a promising strategy for developing novel osteosarcoma therapies.
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