Publication Date:
2013-11-15
Description:
microRNA-155 (miR-155) is a short non-coding RNA that is associated with aggressive cancers and known to promote leukemogenesis. Recently, we have reported that aberrant miR-155 upregulation independently identifies high-risk cytogenetically normal AML patients, suggesting that this miR may also serve as a novel therapeutic target in AML. We and others have shown that miR-155 is positively regulated by NF-kB, a transcription factor that is constitutively activated in leukemic blasts and contributes to their aberrant proliferation and survival. MLN4924 (Millennium Pharmaceuticals Inc) is a novel drug that blocks neddylation and subsequent degradation of the NFkB inhibitor, IkBa, thereby inhibiting translocation of NF-kB to the nucleus. MLN4924 has demonstrated promising activity in early clinical trials for AML. We postulated that downregulation of miR-155 via NF-kB inhibition is at least in part responsible for the antileukemic activity of MLN4924. Methods AML cell lines and primary blasts were treated with 100-1000nM MLN4924 for 3-72 hrs. Messenger RNA and protein levels were determined by quantitative RT-PCR and immunoblotting, respectively. NF-kB activity was measured by luciferase reporter assays. Binding of NF-kB to the miR-155 promoter was detected by electromobility shift assay and Chromatin Immunoprecipitation. Transfection of miR-155 was performed using the siPORT TM NeoFXTM method. Apoptosis was assessed by Annexin V staining. For in vivo studies, we used NOD/SCID/g mice engrafted with MV4-11 cells. Two weeks after transplantation, the engrafted mice received intraperitoneal treatments of 180 mg/kg of MLN4924 every other day for 21 days. Mice in the control group were treated similarly with the vehicle alone (20% 2-hydroxypropyl-betacyclodextrin). Results In AML cell lines and primary AML patient blasts 12hr treatment with MLN4924 resulted in a ∼50% decrease of miR-155 expression at 300nM in THP-1 and MV4-11 cells and at 500nM in AML blasts (p
Print ISSN:
0006-4971
Electronic ISSN:
1528-0020
Topics:
Biology
,
Medicine
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