Bone metastases affect 350,000 people per year in the United States alone. We found that the integrin ?3 global knockout mouse was protected from tumor-associated bone loss and bone metastasis, a finding consistent with the model that tumor cells highjack the ?3 integrin pathways in platelets and osteoclasts, which express express aIIb?3 and av?3, respectively. Both platelets and osteoclasts are host cells that are critical for the growth and survival of tumor cells in the bone environment. A problem with targeting ?3 for bone metastasis is that deletion of the ?3 integrin subunit in all tissues can enhance tumor-associated angiogenesis, most likely as a result of ?3 integrin present on the endothelium and on activated macrophages in the tumor environment. Therefore, pharmacologic inhibition of av?3 may have adverse procancer effects and inhibition of aIIb?3 causes bleeding. To obviate these issues of the germline ?3 knockout we generated mice with a ?3 integrin gene flanked by loxP sites and deleted the gene in platelets and myeloid (macrophage and osteoclast) lineages using tissue-targeted Cre transgenic mice. As alternative approaches to modulating ?3 integrin function in platelets and osteoclasts, we will investigate the roles of the ?3 integrin activating receptor, P2Y12, and a ?3-integrin stimulating protein, CD47, on platelet and osteoclast function and during bone metastasis. In order to avoid the negative effects of global ?3 integrin inhibition and to identify novel therapeutic targets, we will study these ?3 integrin stimulatory pathways that may confer cell type specificity and reduce side effects. Our central hypothesis is that blockade of ?3 integrin stimulatory pathways in platelets and myeloid cells will disrupt tumor growth in bone and tumor-driven osteolysis. Thus, our Specific Aims are to: 1. Define the role of ?3 integrins on platelets and myeloid cells during metastasis to bone and tumor growth in the bone micro-environment. 2. Evaluate the role of the upstream activator of ?3 integrin P2Y12 on platelets and myeloid cells during skeletal metastasis and tumor osteolysis. 3. Evaluate the role of CD47, a ?3 integrin stimulatory protein, as a therapeutic target to abrogate bone metastasis and tumor osteolysis. Intervention strategies to be used in relatively healthy patients with cancer must have side effects that are clinically minimal. Thus the over-arching goal of this project is to design novel neoadjuvant treatment strategies to prevent bone metastasis through targeting ?3 integrin pathways active on platelets and osteoclasts. These studies will lead to identification of optimal drug targets within the ?3 integrin pathway with minimal side effects that overcome the problem of generalized ?3 integrin inhibition, while preventing or decreasing bone metastasis.

National Institute of Health (NIH)
National Cancer Institute (NCI)
Research Project (R01)
Project #
Application #
Study Section
Tumor Microenvironment Study Section (TME)
Program Officer
Mohla, Suresh
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
Washington University
Internal Medicine/Medicine
Schools of Medicine
Saint Louis
United States
Zip Code
Murali, Bhavna; Ren, Qihao; Luo, Xianmin et al. (2018) Inhibition of the Stromal p38MAPK/MK2 Pathway Limits Breast Cancer Metastases and Chemotherapy-Induced Bone Loss. Cancer Res 78:5618-5630
Ross, Michael H; Esser, Alison K; Fox, Gregory C et al. (2017) Bone-Induced Expression of Integrin ?3 Enables Targeted Nanotherapy of Breast Cancer Metastases. Cancer Res 77:6299-6312
Fontana, Francesca; Ge, Xia; Su, Xinming et al. (2017) Evaluating Acetate Metabolism for Imaging and Targeting in Multiple Myeloma. Clin Cancer Res 23:416-429
Su, Xinming; Esser, Alison K; Amend, Sarah R et al. (2016) Antagonizing Integrin ?3 Increases Immunosuppression in Cancer. Cancer Res 76:3484-95
D'Amico, Lucia; Mahajan, Sahil; Capietto, Aude-Hélène et al. (2016) Dickkopf-related protein 1 (Dkk1) regulates the accumulation and function of myeloid derived suppressor cells in cancer. J Exp Med 213:827-40
Luo, Xianmin; Fu, Yujie; Loza, Andrew J et al. (2016) Stromal-Initiated Changes in the Bone Promote Metastatic Niche Development. Cell Rep 14:82-92
Esser, Alison K; Schmieder, Anne H; Ross, Michael H et al. (2016) Dual-therapy with ?v?3-targeted Sn2 lipase-labile fumagillin-prodrug nanoparticles and zoledronic acid in the Vx2 rabbit tumor model. Nanomedicine 12:201-11
Amend, Sarah R; Uluckan, Ozge; Hurchla, Michelle et al. (2015) Thrombospondin-1 regulates bone homeostasis through effects on bone matrix integrity and nitric oxide signaling in osteoclasts. J Bone Miner Res 30:106-15
Ellison, Tim S; Atkinson, Samuel J; Steri, Veronica et al. (2015) Suppression of ?3-integrin in mice triggers a neuropilin-1-dependent change in focal adhesion remodelling that can be targeted to block pathological angiogenesis. Dis Model Mech 8:1105-19
Sanfilippo, K M; Gage, B; Luo, S et al. (2015) Comparative effectiveness on survival of zoledronic acid versus pamidronate in multiple myeloma. Leuk Lymphoma 56:615-21

Showing the most recent 10 out of 36 publications