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Leukemia. 2013 Dec;27(12):2341-50. doi: 10.1038/leu.2013.94. Epub 2013 Mar 29.

Disruption of the MYC-miRNA-EZH2 loop to suppress aggressive B-cell lymphoma survival and clonogenicity.

Author information

1
Department of Malignant Hematology and Experimental Therapeutics Program, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL, USA.

Abstract

c-MYC (hereafter MYC) overexpression has been recognized in aggressive B-cell lymphomas and linked to adverse prognosis. MYC activation results in widespread repression of micro-RNA (miRNA) expression and associated with lymphoma aggressive progression. Our recent study identified a MYC-miRNA-EZH2 feed-forward loop linking overexpression of MYC, EZH2 and miRNA repression. Here, using a novel small-molecule BET bromodomain inhibitor, JQ1, and the EZH2 inhibitor, DZNep, we demonstrated that combined treatment of JQ1 and DZNep cooperatively disrupted MYC activation, resulting in a greater restoration of miR-26a expression and synergistically suppressed lymphoma growth and clonogenicity in aggressive lymphoma cells. Furthermore, CHIP assay demonstrated that MYC recruited EZH2 to miR-26a promoter and cooperatively repressed miR-26a expression in aggressive lymphoma cell lines, as well as primary lymphoma cells. Loss- or gain-of-function approaches revealed that miR-26a functioned as a tumor suppressor miRNA and mediated the combinatorial effects of JQ1 and DZNep. These findings represent a novel promising approach for silencing MYC-miRNA-EZH2 amplification loop for combinatorial therapy of aggressive B-cell lymphomas.

PMID:
23538750
PMCID:
PMC4015113
DOI:
10.1038/leu.2013.94
[Indexed for MEDLINE]
Free PMC Article

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