LncRNA NEAT1 sponges miR-214 to regulate M2 macrophage polarization by regulation of B7-H3 in multiple myeloma

•LncRNA NEAT1 and B7-H3 were up-regulated, while miR-214 was down-regulated in multiple myeloma patients.•Upregulation of NEAT1 and B7-H3 and downregulation of miR-214 associated with poor survival in multiple myeloma patients.•LncRNA NEAT1 sponged miR-214 to regulate the expression of B7-H3 to regulate M2 macrophage polarization in multiple myeloma.•B7-H3 promoted M2 macrophage polarization via activating JAK2/STAT3 signaling.•MiR-214 inhibitor reversed the effects of NEAT1 silencing on M2 macrophage polarization. LncRNA NEAT1 was associated with the tumorigenesis of multiple myeloma (MM). However, the mechanisms of M2 macrophage polarization involved with NEAT1 in MM are still unknown. Bone marrow samples, multiple myeloma cells RPMI 8226 and monocyte cell line THP-1 were used in this study. The expression of NEAT1 and miR-214 was modified by transfection with the shNEAT1 or miR-214 inhibitor. The expression of NEAT1, miR-214 and B7-H3 in MM patient tissues and cells was analyzed by RT-qPCR. ELISA assay was used to determine the release of B7-H3 in the supernatant of cell culture. The patient survival curve was analyzed using Kaplan-Meier method. The macrophage polarization markers were examined by RT-qPCR and western blotting. The interaction between NEAT1, miR-214 and B7-H3 was analyzed by Dual-Luciferase reporter and RIP assays. AG490 was used to block the JAK2/STAT3 signaling. Co-culture of THP-1 and RPMI 8226 cells was used for macrophage polarization. NEAT1 and B7-H3 were up-regulated, but miR-214 was obviously down-regulated in MM patients. B7-H3, NEAT1 and miR-214 were associated with overall survival time of MM patients. NEAT1 silencing induced miR-214 and inhibited the expression and release of B7-H3 and then suppressed M2 macrophage polarization via inhibiting the JAK2/STAT3 signaling. NEAT1 directly targeted miR-214, and miR-214 directly bound to B7-H3. MiR-214 inhibitor reversed the down-regulation and release of B7-H3 and M2 macrophage polarization caused by shNEAT1. The specific JAK2/STAT3 signaling inhibitor AG490 abrogated M2 macrophage polarization. NEAT1 promoted M2 macrophage polarization by sponging miR-214 and then regulating B7-H3, thus accelerating MM progression via the JAK2/STAT3 signaling pathway. Our study revealed novel mechanisms of M2 macrophage polarization and provided new potential clinical therapeutic targets for MM.