CXCR7-mediated progression of osteosarcoma in the lungs

Background: Osteosarcoma (OS) is the most frequent primary malignant bone tumour in children and adolescents with a high propensity for lung metastasis. Chemokines and chemokine receptors have been described to have an important role in many malignancies including OS. The aim of this study was to investigate the expression of CXCR7 receptor in OS tissues and its role in the progression of the disease in the lungs. Methods: Immunohistochemistry was used to study CXCR7 expression in primary tumours and metastatic tissues from patients with OS. Its contribution to tumour expansion in the lungs has been also assessed using animal models and synthetic-specific CXCR7 ligands. Results: CXCR7 was expressed on human primary bone tumours and on lung metastases. Its expression was predominantly located on tumour-associated blood vessels. Mice challenged with OS cells and systematically treated with synthetic CXCR7 ligands presented a significant reduction of lung nodules compared with untreated mice. Conclusion: This study shows that CXCR7 has a critical role in OS progression in the lungs, where are expressed CXCR7 ligands, especially CXCL12. Moreover, we highlight that synthetic CXCR7 ligands could represent a powerful therapeutic tool to impede lung OS progression.