Asiaticoside reverses M2 phenotype macrophage polarization-evoked osteosarcoma cell malignant behaviour by TRAF6/NF-κB inhibition.

Context: M2 phenotype macrophage polarization is an attractive target for therapeutic intervention. Asiaticoside (ATS) has multiple pharmacological functions. Objective: This study investigates the effect of ATS on M2 phenotype macrophage polarization in osteosarcoma. Materials and methods: The differentiation of human THP-1 monocytes into M0 phenotype macrophages was induced by 100nM phorbol myristate acetate for 24 h, and treated with 20 ng/mL IL-4 and 20 ng/mL IL-13 for 48 h to obtain M2 phenotype macrophages. The function of ATS on the growth and invasion was investigated by cell counting kit-8, transwell, and western blot under the co-culture of M2 phenotype macrophages and osteosarcoma cells for 24 h. The mechanism of ATS on osteosarcoma was assessed using molecular experiments. Results: ATS reduced the THP-1 cell viability with an IC50 of 128.67 lM. Also, ATS repressed the M2 phenotype macrophage polarization induced by IL-4/IL-13, and the effect was most notably at a 40 lM dose. ATS (40 lM) restrained the growth and invasion of osteosarcoma cells induced by M2 phenotype macrophages. In addition, ATS reduced the tumour necrosis factor receptor-associated factor 6 (TRAF6)/NF-jB activity in osteosarcoma cells and the TRAF6 knockdown reduced the growth and invasion of osteosarcoma cells induced by M2 phenotype macrophages. TRAF6 (2 lg/mL) attenuated the inhibitory effect of ATS on the growth and invasion of osteosarcoma cells caused by M2 phenotype macrophages. In vivo studies further confirmed ATS (2.5, 5, or 10 mg/kg) repressed osteosarcoma tumour growth. Discussion and conclusions: ATS reversed M2 phenotype macrophage polarization-evoked osteosarcoma cell malignant behaviour by reducing TRAF6/NF-jB activity, suggesting ATS might be a promising drug for the clinical treatment of osteosarcoma. [ABSTRACT FROM AUTHOR]