title: Progression of Osteosarcoma from a Non-Metastatic to a Metastatic Phenotype Is Causally Associated with Activation of an Autocrine and Paracrine uPA Axis.
abstract: Pulmonary metastasis is the major untreatable complication of osteosarcoma (OS) resulting in 10-20% long-term survival. The factors and pathways regulating these processes remain unclear, yet their identification is crucial in order to find new therapeutic targets. In this study we used a multi-omics approach to identify molecules in metastatic and non-metastatic OS cells that may contribute to OS metastasis, followed by validation in vitro and in vivo. We found elevated levels of the urokinase plasminogen activator (uPA) and of the uPA receptor (uPAR) exclusively in metastatic OS cells. uPA was secreted in soluble form and as part of the protein cargo of OS-secreted extracellular vesicles, including exosomes. In addition, in the tumour microenvironment, uPA was expressed and secreted by bone marrow cells (BMC), and OS- and BMC-derived uPA significantly and specifically stimulated migration of metastatic OS cells via uPA-dependent signaling pathways. Silencing of uPAR in metastatic OS cells abrogated the migratory response to uPA in vitro and decreased metastasis in vivo. Finally, a novel small-molecule inhibitor of uPA significantly (P = 0.0004) inhibited metastasis in an orthotopic mouse model of OS. Thus, we show for the first time that malignant conversion of OS cells to a metastatic phenotype is defined by activation of the uPA/uPAR axis in both an autocrine and paracrine fashion. Furthermore, metastasis is driven by changes in OS cells as well as in the microenvironment. Finally, our data show that pharmacological inhibition of the uPA/uPAR axis with a novel small-molecule inhibitor can prevent the emergence of metastatic foci.
authors: The University of Queensland Diamantina Institute, Translational Research Institute, Brisbane, Queensland 4102, Australia.
authors: Liliana
authors: L
authors: Endo-Munoz
authors: The University of Queensland Diamantina Institute, Translational Research Institute, Brisbane, Queensland 4102, Australia.
authors: Na
authors: N
authors: Cai
authors: The University of Queensland Diamantina Institute, Translational Research Institute, Brisbane, Queensland 4102, Australia.
authors: Andrew
authors: A
authors: Cumming
authors: The University of Queensland Diamantina Institute, Translational Research Institute, Brisbane, Queensland 4102, Australia.
authors: Rebecca
authors: R
authors: Macklin
authors: The University of Queensland Diamantina Institute, Translational Research Institute, Brisbane, Queensland 4102, Australia.
authors: Lilia
authors: L
authors: Merida de Long
authors: The University of Queensland Diamantina Institute, Translational Research Institute, Brisbane, Queensland 4102, Australia.
authors: Eleni
authors: E
authors: Topkas
authors: The University of Queensland Diamantina Institute, Translational Research Institute, Brisbane, Queensland 4102, Australia.
authors: Pamela
authors: P
authors: Mukhopadhyay
authors: The University of Queensland Diamantina Institute, Translational Research Institute, Brisbane, Queensland 4102, Australia.
authors: Michelle
authors: M
authors: Hill
authors: The University of Queensland Diamantina Institute, Translational Research Institute, Brisbane, Queensland 4102, Australia.
authors: Nicholas A
authors: NA
authors: Saunders
mesh_terms: D000818:Animals; D019898:Autocrine Communication; D001859:Bone Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D045744:Cell Line, Tumor; D002465:Cell Movement; D049109:Cell Proliferation; D018450:Disease Progression; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008113:Liver Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology / Q000556:secondary*; D051379:Mice; D009368:Neoplasm Transplantation; D012516:Osteosarcoma / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D019899:Paracrine Communication; D055293:Receptors, Urokinase Plasminogen Activator / Q000235:genetics / Q000378:metabolism*; D014568:Urokinase-Type Plasminogen Activator / Q000235:genetics / Q000378:metabolism*
chemical_list: D055293:Receptors, Urokinase Plasminogen Activator; D014568:Urokinase-Type Plasminogen Activator