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Background: miR-302 cluster has been reported as a tumor suppressor in many human cancers; yet, its function in chronic myeloid leukemia (CML) tumorigenesis remains largely unclear. The study was aimed to explore the functional roles of miR-302 cluster in CML progression.
Materials and methods: Quantitative reverse transcriptase PCR and Western blot were performed to evaluate miR-302 cluster and vascular endothelial growth factor A (VEGFA) expression levels. Cell Counting Kit-8 assay, colony formation assay and human umbilical vein endothelial cell line capillary tube formation were used to determine the influence of miR-302 cluster on the growth and angiogenesis of K562 cells, respectively. Luciferase reporter assay was employed to confirm the direct target interaction between miR-302 cluster and VEGFA.
Results: This study demonstrated that miR-302 cluster was frequently downregulated in CML samples and cell lines and high level of miR-302 cluster was significantly associated with good prognosis of CML patients. Compared with miRNA negative control, miR-302 cluster mimics obviously suppressed cell growth, colony formation and angiogenesis. Further studies revealed that VEGFA was a direct target gene of miR-302 cluster. Moreover, overexpression of VEGFA dramatically abated the inhibition of miR-302 cluster on cell growth and angiogenesis.
Conclusion: The present study, for the first time, identified miR-302 cluster as a tumor suppressor, and overexpression of miR-302 cluster inhibited growth and angiogenesis in K562 cells. miR-302 cluster may be a potential therapeutic target in CML to develop the adjuvant antiangiogenic therapy based on VEGFA.
Keywords: chronic myeloid leukemia, angiogenesis, miR-302, VEGFA