Impact and underlying mechanisms of osteoblast-derived exosomes on biological characteristics of prostate cancer cells

Objective To investigate the effects and potential mechanisms of osteoblast-derived exosomes on the biological properties of prostate cancer (PC) cells. Methods Human bone marrow mesenchymal stem cells was induced to differentiate into osteoblasts, and then the exosomes were extracted from the supernatant of cell culture medium by ultracentrifugation and identified. Clone formation assay was employed to determine the effect of derived exosomes on the proliferation of PC cells, and PCR microarray was used to analyze miRNA changes after exosome treatment. Fluorescence labeling was applied to validate the transfer of miRNA between osteoblasts and tumor cells. The impact of key miRNA on the biological characteristics of PC cells was studied at the cellular and animal levels. Bioinformatics analysis was conducted to explore the target genes of key miRNA and then further validated. Results Osteoblast-derived exosomes were successfully extracted and then identified. These exosomes significantly promoted the clonogenic ability of PC cells when compared with the cells without treatment (P < 0.05). PCR microarray showed that miR-223 might be a key molecule in this process. Membrane exchange experiments demonstrated the presence of membrane exchange between osteoblasts and PC cells, and miRNA FAM labeling displayed that miR-223 was transferred within above cells. Functional experiments indicated that overexpression of miR-223 enhanced the proliferation, anti-apoptosis, and migration/invasion ability of PC cells (P < 0.05). Bioinformatics analysis indicated that APC, an inhibitor of WNT signaling pathway, may be a target gene of miR-223, which was further confirmed that overexpressing miR-223 down-regulated APC expression. Rescue experiment showed that overexpression of APC reversed the promoting effect of miR-223 on the proliferation, migration and invasion of PC cells. Conclusion Osteoblast-derived exosomes are pro-carcinogenic factors in PC, and miR-223 may be a key molecule in exosomes, which plays a oncogenic role by regulating APC in PC cells.