nature文章讲稿--RNAi screen identifies Brd4 as a therapeutic target in acute myeloid leukaemia.pptVIP

RNAi screen identifies Brd4 as atherapeutic target in acute myeloid leukaemia AML represents a paradigm for understanding how complex patterns of cooperating genetic and epigenetic alterations lead to tumorigenesis. One key event in AML initiation is the corruption of cell-fate programs to generate leukaemia stem cells that aberrantly self-renew and thereby maintain and propagate the disease. This process has been linked to changes in regulatory chromatin modifications. For example, common AML oncogenes such as those encoding the AML1-ETO and MLL fusion proteins induce self-renewal programs at least in part through reprogramming of epigenetic pathways. Because epigenetic alterations induced by oncogenic stimuli are potentially reversible,chromatin regulators are being explored as candidate drug targets. 1. RNAi screening strategy a custom shRNA library targeting 243 known chromatin regulators The result: 177 shRNAs targeting 38 genes were strongly depleted. These included all eight positive-control shRNAs targeting essential genes (Rpa1, Rpa3, Pcna and Polr2b), as well as several shRNAs targeting two known MLL-AF9 cofactors (Men1 and Psip1). Genes for which at least two independent shRNAs scored were subjected to extensive one-by-one validation using an independent MLL-AF9/NrasG12D AML cell line and vector system. 2.Investigate the suitability of Brd4 asan AML drug target. BRD4 is a member of the BET family of Bromodomain containing proteins that bind to acetylated histones to influence transcription. Brd4 is also a proto-oncogene that can be mutated via chromosomal translocation in a rare form of Squamous cell carcinoma. 3.Examin the sensitivity of leukaemia cells to JQ1. 4.Investigate the relevance of Brd4 to AML progression in vivo. Brd4 knockdown resulted in a marked delay in leukaemia progression and a survival benefit. 5. Examine whether JQ1 has