[Exosomes derived from mesenchymal stem cells loaded with annexin A2 reduce the polarization of M2 macrophages to inhibit the growth of prostate cancer cells in nude mice].

Abstract

Objective To identify the effect of exosomes derived from bone marrow mesenchymal stem cells (BMSCs) loaded with annexin A2 (ANXA2) on the proliferation, migration, invasion of prostate cancer cells, and the transplanted tumor of prostate cancer in nude mice growth, as well as the role of macrophages in this process. Methods BMSCs from BALB/c nude mice were isolated and cultured. BMSCs were infected with lentiviral plasmids loaded with ANXA2. Exosomes were isolated and then added to treat THP-1 macrophages. ELISA was used to detect the levels of tumor necrosis factor-α (TNF-α), interleukin 1β (IL-1β), IL-6 and IL-10 in the cell supernatant culture fluid; After co-culturing the exosomes-treated macrophages and prostate cancer cells, CCK-8 assay was used to detect the cell proliferation activity. Also, Transwell^TM chamber were used to detect the cell invasion and migration. A nude mouse xenograft model of prostate cancer was constructed by injecting PC-3 human prostate cancer cells, the modeled nude mice were randomly divided into a control group and an experimental group, with 8 mice in each group. The nude mice in experimental group were injected with 1 mL of Exo-ANXA2 through the tail vein, while the control group was injected with the same amount of PBS, on days 0, 3, 6, 9, 12, 15, 18, and 21 after injection. Then the tumor volume was measured and calculated with vernier calipers. The nude mice were sacrificed at 21 days with their the tumor mass measured. The immunohistochemical staining method was used to detect the expression of antigen KI-67 (ki67) and CD163 expression in tumor tissue. Results The cells isolated from bone marrow showed high expression of CD90 and CD44 on the surface, and low expression of CD34 and CD45, and had strong osteogenic adipogenic differentiation ability, indicating that BMSCs were successfully obtained. After infection with the lentiviral plasmid carrying ANXA2, a strong green fluorescent protein expression in BMSCs, and Exo-ANXA2 was isolated. After Exo-ANXA2 treatment, the levels of TNF-α and IL-6 in THP-1 cells increased significantly, while the levels of IL-10 and IL-13 decreased significantly. Exo-ANXA2 treatment of macrophages significantly inhibited Exo-ANXA2 and promoted the proliferation, invasion and migration of PC-3 cells. After injecting Exo-ANXA2 into nude mice with prostate cancer cells transplantation, the tumor tissue volume of nude mice was significantly reduced on the 6th, 9th, 12th, 15th, 18th, and 21st days, and the tumor mass of nude mice was also significantly reduced on the 21st day. In addition, the positive expression rates of ki67 and CD163 in tumor tissues were significantly reduced. Conclusion Exo-ANXA2 can inhibit the proliferation, invasion and migration of prostate cancer cells, and suppress the growth of prostate cancer xenografts in nude mice by reducing M2 macrophages.