Background: Circular RNAs (circRNAs) play a crucial role in tumorigenesis. However, the effects of circRNAs on acute myeloid leukemia (AML) remain largely unexplored. We explored the function of circRAD18 in AML development.
Methods: QRT-PCR was performed for the levels of circRAD18, RAD18, microRNA-206 (miR-206) and protein kinase CAMP-activated catalytic subunit beta  (PRKACB ). Cell Counting Kit-8 (CCK-8) assay and colony formation assay were utilized for cell proliferation. Flow cytometry analysis was carried out to analyze cell apoptosis and cell cycle process. Transwell assay was manipulated for cell migration and invasion. Western blot assay was conducted for protein levels. Dual-luciferase reporter assay was adopted to verify the interaction between miR-206 and circRAD18 or PRKACB .
Results: CircRAD18 level was increased in AML patients’ blood specimens and AML cell lines compared to normal controls. CircRAD18 knockdown impeded the proliferation, migration and invasion and facilitated the apoptosis and cell cycle arrest in AML cells. Moreover, circRAD18 was identified as a sponge for miR-206, and circRAD18 knockdown-mediated effect on AML cell progression was reversed by miR-206 suppression. Additionally, PRKACB  was the target gene of miR-206. MiR-206 overexpression suppressed the malignant behaviors of AML cells, while PRKACB  elevation restored the effects.
Conclusion: CircRAD18 aggravated the malignancy of AML cells through reducing miR-206 expression and elevating PRKACB  expression, indicating circRAD18 might be a therapeutic target for AML.
Keywords: AML, circRAD18, miR-206, PRKACB