Exosomes from BM-MSCs promote acute myeloid leukemia cell proliferation, invasion and chemoresistance via upregulation of S100A4

BM-MSCs play an important role in cancer development through the release of cytokines or exosomes. Studies have shown that extracellular exosomes derived from BM-MSCs are a key pro-invasive factor. However, how BM-MSC-exos influence AML cell proliferation, invasion and chemoresistance remains poorly understood. We isolated exosomes from BM-MSCs and used electron microscopy, particle size separation and western blots to identify the exosomes. The invasion of leukemia cells was observed with a transwell assay. The stemness traits and chemoresistance of the leukemia cells were detected by FCM, colony formation and CCK-8 assays. TCGA database was used to investigate the prognostic relevance of S100A4 and its potential role in AML. In this study, we found that BM-MSC-exos increased the metastatic potential, maintained the stemness and contributed to the chemoresistance of leukemia cells. Mechanistically, BM-MSC-exos promoted the proliferation, invasion and chemoresistance of leukemia cells via upregulation of S100A4. Downregulating S100A4 clearly suppressed the proliferation, invasion, and chemoresistance of leukemia cells after treatment with BM-MSC-exos. Bioinformatic analysis with data in TCGA database showed that S100A4 was associated with poor prognosis in AML patients, and functional enrichment revealed its involvement in the processes of cell-cell adhesion and cytokine regulation. S100A4 is vital in the BM-MSC-exo-driven proliferation, invasion and chemoresistance of leukemia cells and may serve as a potential target for leukemia therapy.