Colony-stimulating factor-1 of osteosarcoma cells promotes tumor angiogenesis / 肿瘤

ABSTRACT

Objective: To investigate the effect of macrophage colony-stimulating factor-1 (CSF-1) expression in osteosarcoma cells on tumor angiogenesis, and to explore its possible mechanism. Methods: The expressions of CSF-1 and allograft inflammatory factor-1 (AIF-1) in human osteoblasts hFOB1.19, osteosarcoma SAOS-2, MG-63 and U2OS cells were detected by Western blotting. The expressions of AIF-1 and Ras-related C3 botulinum toxin substrate-1 (Rac-1) in osteosarcoma SAOS-2 cells after transfection with siRNA-CSF-1 or siRNAnegative control (siRNA-NC) were detected by Western blotting. The culture supernatant was collected after siRNA-CSF-1 or siRNA-NC was transfected into osteosarcoma SAOS-2 cells, the untransfected SAOS-2 cells were used as the blank control (BC). Then the collected culture supernatant was mixed with the complete medium at a volume ratio of 1∶1 to make the conditioned medium for the culture of human umbilical vein endothelial cells (HUVECs). After treatment with the siRNA-CSF-1 or siRNA-NC conditional medium, the proliferation, migration and tube formation of HUVECs were detected by MTT assay, Transwell chamber assay and tube formation experiment, respectively; The expressions of vascular endothelial growth factor (VEGF) and Rac-1 in HUVECs were detected by Western blotting. After HUVECs were treated with siRNA-CSF-1 conditional medium combined with 0.1% DMSO or Rac-1 activator phorbol 12-myristate 13-acetate (PMA) for 24 h, the cell proliferation, migration and the tube formation were detected by MTT assay, Transwell chamber assay and tube formation experiment, respectively; The expressions of VEGF and Rac-1 in HUVECs were detected again by Western blotting. Results: The expression levels of CSF-1 and AIF-1 proteins in osteosarcoma SAOS-2, MG-63 and U2OS cells were higher than those in osteoblasts hFOB1.19 (all P < 0.05). The expressions of CSF-1 and AIF-1 were positively correlated (R2 = 0.492 2, P = 0.001 2). The expression levels of AIF-1 and Rac-1 in osteosarcoma SAOS-2 cells of siRNA-CSF-1 transfection group were down-regulated (both P < 0.05). After treatment with siRNA-CSF-1 conditional medium, the proliferation, migration and tube formation abilities of HUVECs were decreased (all P < 0.05), and the expression levels of VEGF and Rac-1 were down-regulated (both P < 0.05). Whereas Rac-1 activator reversed the effects of siRNA-CSF-1 conditional medium on the proliferation, migration, tube formation as well as VEGF and Rac-1 expressions of HUVECs (all P < 0.05). Conclusion: CSF-1 in osteosarcoma cells may promote the tumor angiogenesis by AIF-1/ Rac-1 pathway.