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

ABSTRACT

BACKGROUND: 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. METHODS: 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. RESULTS: 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. CONCLUSION: 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.