MiR-92a mediates AZD6244 induced apoptosis and G1-phase arrest of lymphoma cells by targeting Bim.

AZD6244, an ATP-uncompetitive inhibitor of mitogen-activated protein kinase 1/2 (MEK1/2), has shown activity in several malignant tumours. However, whether AZD6244 has a function in lymphoma cells is not known. We report that AZD6244 treatment represses the growth of Raji and MOLT4 cells by inducing apoptosis and G1-phase arrest. Using miRNAs array and quantitative RT-PCR, miR-92a was downregulated byAZD6244 treatment through the ERK1/2-AP1 signalling pathway. Overexpression of miR-92a abrogated AZD6244-induced apoptosis and G1-phase arrest, indicating that it is involved in the cytotoxicity of AZD6244 in lymphoma cells. A luciferase reporter assay showed that miR-92a directly targetsthe 3'-UTRs of Bim. Overexpression of miR-92a mimics downregulated Bim mRNA and protein expression level, indicating that miR-92a negatively regulates its expression at both levels. Silencing Bim decreases AZD6244-induced apoptosis and G1-phase arrest, suggesting that Bim contributes to the growth arrest. Thus, miR-92a mediates AZD6244-induced cytotoxicity of lymphoma cells by targeting Bim. Downregulation of miR-92a by AZD6244 is mediated by the ERK1/2-AP1 signalling pathway.

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