Tumor-associated M2 macrophages enhance migration and invasion of lung adenocarcinoma A549 cells by regulating the expression of VEGFR3 / 肿瘤

ABSTRACT

Objective: To investigate the role of M2-type macrophages in migration and invasion of lung adenocarcinoma A549 cells, and to explore the possible mechanism and the related signaling pathway. Methods: PMA (phorbol 12-myristate 13-acetate) was used to induce THP-1 cells into M2- type macrophages. The non-contacting co-culture model of M2-type macrophages and A549 cells was established by Transwell method, then the co-culture medium was collected. The migration and invasion abilities of A549 cells after treatment with co-culture medium (named as CO-A549 cells) were detected by the wound-healing assay and Transwell chamber invasion assay, respectively. The expression levels of vascular endothelial growth factor receptor 3 (VEGFR3) and vascular endothelial growth factor-C (VEGF-C) in CO-A549 cells were detected by Western blotting. After treatment with VEGFR3 inhibitor MAZ51, the migration and invasion abilities of CO-A549 cells were detected by wound-healing assay and Transwell invasion assay again, and the expression level of phospho-extracellular signal-regulated protein kinase (p-ERK) in CO-A549 cells was detected by Western blotting. Finally, the expression level of matrix metalloproteinase 2 (MMP-2) mRNA in CO-A549 cells after treatment with MAZ51 or U0126, an inhibitor of mitogen-activated protein kinase (MAPK)/ERK pathway, was detected by RT-PCR. Results: M2-type macrophages were induced for from THP-1cells by PMA. After treatment with the co-culture medium, the migration and invasion abilities of A549 cells were significantly enhanced (both P < 0.01), the expression level of VEGFR3 was significantly improved (P < 0.01). After inhibition of VEGFR3, the migration and invasion abilities of CO-A549 cells were decreased (P < 0.01, P < 0.05), and the expression level of p-ERK was down-regulated (P < 0.05). The expression of MMP-2 mRNA was down-regulated in CO-A549 cells after treatment with MAZ51 or U0126 (both P < 0.05). Conclusion: M2-type macrophages which were induced by PMA from THP-1 cells can promote the migration and invasion of A549 cells by up-regulating the expression of VEGFR3. The mechanism may be related to the activation of the MAPK/ERK signaling pathway.