The toll of advanced breast cancer on women's lives remains unacceptably high and new approaches are needed to treat this disease. The purpose of this proposal is to investigate a novel cell surface receptor that orchestrates pericellular protease activities and thus, modulates the tumor microenvironment, and to test whether this receptor may serve as a therapeutic target in advanced breast cancer. The broad, long term goal of this proposal is to identify new mechanisms for treating late-stage breast cancer. This proposal is based on our discovery of a new protein, the plasminogen receptor, Plg-RKT, which promotes activation of plasminogen to the broad spectrum protease, plasmin. Cell surface plasmin regulates the tumor microenvironment by effecting degradation of the ECM and release of growth factors from the ECM. Our preliminary data show that Plg-RKT is highly expressed in human invasive ductal carcinoma and metastatic human breast tumor cell lines. Furthermore, our function blocking anti-Plg-RKT mAb reduced lung metastases in a xenograft model of human breast cancer. Interestingly, in a previously published genome-scale quantitative image analysis, overexpression of more than 86 cDNAs, including the Plg-RKT cDNA, resulted in dramatic increases in cell proliferation whereas knockdown of Plg-RKT mRNA resulted in apoptosis, underscoring the oncogenic potential of this gene product. In microarray studies, Plg-RKT mRNA expression had a high power to predict cervical lymph node metastasis in oral squamous cell carcinoma. The central hypothesis to be addressed in this proposal is that Plg-RKT is a missing link that acts in synergy with other components of the plasminogen activation system to modulate the tumor microenvironment in breast cancer progression. To address our hypothesis, our specific aims are: 1) to determine the role of Plg-RKT in mammary gland remodeling and mammary tumor progression;2) to identify specific mechanisms by which Plg-RKT regulates growth and metastasis of human breast cancer;3) to evaluate Plg-RKT as a potential target in advanced breast cancer. Studies will be performed in breast tumor cell-based assays in vitro and in vivo using novel function-blocking anti-Plg-RKT antibodies and a new Plg-RKT knockout mouse model. We will determine expression of Plg-RKT in microarray studies of human breast cancer and assess the therapeutic potential of anti-Plg-RKT antibody in preclinical studies. We expect that performance of our specific aims will implicate Plg-RKT as a major new therapeutic target in advanced breast cancer.

Public Health Relevance

The proposed research is relevant to public health because its goal is to identify new mechanisms for treating late-stage breast cancer. The proposed studies address targeting the plasminogen activation system in breast cancer from an entirely new angle, via interfering with the function of a novel cell surface receptor. The results of these studies are expected to provide multiple lines of evidence to implicate this receptor as a new therapeutic target in advanced breast cancer.

National Institute of Health (NIH)
National Cancer Institute (NCI)
Research Project (R01)
Project #
Application #
Study Section
Tumor Microenvironment Study Section (TME)
Program Officer
Ault, Grace S
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
Torrey Pines Institute for Molecular Studies
Port Saint Lucie
United States
Zip Code
Miles, L A; Baik, N; Bai, H et al. (2018) The plasminogen receptor, Plg-RKT, is essential for mammary lobuloalveolar development and lactation. J Thromb Haemost 16:919-932
Sugimoto, Michelle A; Ribeiro, Ana Luíza C; Costa, Bruno R C et al. (2017) Plasmin and plasminogen induce macrophage reprogramming and regulate key steps of inflammation resolution via annexin A1. Blood 129:2896-2907
Miles, L A; Baik, N; Lighvani, S et al. (2017) Deficiency of plasminogen receptor, Plg-RKT , causes defects in plasminogen binding and inflammatory macrophage recruitment in vivo. J Thromb Haemost 15:155-162
Briens, Aurélien; Bardou, Isabelle; Lebas, Héloïse et al. (2017) Astrocytes regulate the balance between plasminogen activation and plasmin clearance via cell-surface actin. Cell Discov 3:17001
Miles, Lindsey A; Parmer, Robert J (2016) Angry macrophages patrol for fibrin. Blood 127:1079-80
Miles, Lindsey A; Lighvani, Shahrzad; Baik, Nagyung et al. (2014) New insights into the role of Plg-RKT in macrophage recruitment. Int Rev Cell Mol Biol 309:259-302
Miles, Lindsey A; Parmer, Robert J (2014) Setting the table for macrophages. Blood 124:665-6
Gingles, N A; Bai, H; Miles, L A et al. (2013) Peptidergic regulation of plasminogen activator inhibitor-1 gene expression in vivo. J Thromb Haemost 11:1707-15
Miles, Lindsey A; Parmer, Robert J (2013) Plasminogen receptors: the first quarter century. Semin Thromb Hemost 39:329-37