Pivotal role of IL-8 derived from the interaction between osteosarcoma and tumor-associated macrophages in osteosarcoma growth and metastasis via the FAK pathway.

The prognosis of osteosarcoma (OS) has remained stagnant over the past two decades, requiring the exploration of new therapeutic targets. Cytokines, arising from tumor-associated macrophages (TAMs), a major component of the tumor microenvironment (TME), have garnered attention owing to their impact on tumor growth, invasion, metastasis, and resistance to chemotherapy. Nonetheless, the precise functional role of TAMs in OS progression requires further investigation. In this study, we investigated the interaction between OS and TAMs, as well as the contribution of TAM-produced cytokines to OS advancement. TAMs were observed to be more prevalent in lung metastases compared with that in primary tumors, suggesting their potential support for OS progression. To simulate the TME, OS and TAMs were co-cultured, and the cytokines resulting from this co-culture could stimulate OS proliferation, migration, and invasion. A detailed investigation of cytokines in the co-culture conditioned medium (CM) revealed a substantial increase in IL-8, establishing it as a pivotal cytokine in the process of enhancing OS proliferation, migration, and invasion through the focal adhesion kinase (FAK) pathway. In an in vivo model, co-culture CM promoted OS proliferation and lung metastasis, effects that were mitigated by anti-IL-8 antibodies. Collectively, IL-8, generated within the TME formed by OS and TAMs, accelerates OS proliferation and metastasis via the FAK pathway, thereby positioning IL-8 as a potential novel therapeutic target in OS.