title: MDM2 antagonists induce p53-dependent apoptosis in AML: implications for leukemia therapy.
abstract: Although TP53 mutations are rare in acute myeloid leukemia (AML), inactivation of wild-type p53 protein frequently occurs through overexpression of its negative regulator MDM2 (murine double minute 2). Recently, small-molecule antagonists of MDM2, Nutlins, have been developed that inhibit the p53-MDM2 interaction and activate p53 signaling. Here, we study the effects of p53 activation by Nutlin-3 in AML cells. Treatment with MDM2 inhibitor triggered several molecular events consistent with induction of apoptosis: loss of mitochondrial membrane potential, caspase activation, phosphatidylserine externalization, and DNA fragmentation. There was a positive correlation in primary AML samples with wild-type p53 between baseline MDM2 protein levels and apoptosis induced by MDM2 inhibition. No induction of apoptosis was observed in AML samples harboring mutant p53. Colony formation of AML progenitors was inhibited in a dose-dependent fashion, whereas normal CD34+ progenitor cells were less affected. Mechanistic studies suggested that Nutlin-induced apoptosis was mediated by both transcriptional activation of proapoptotic Bcl-2 family proteins, and transcription-independent mitochondrial permeabilization resulting from mitochondrial p53 translocation. MDM2 inhibition synergistically enhanced cytotoxicity of cytosine arabinoside and doxorubicin in AML blasts but not in normal hematopoietic progenitor cells. p53 activation by targeting the p53-MDM2 interaction might offer a novel therapeutic strategy for AML that retain wild-type p53.
authors: Section of Molecular Hematology and Therapy, Department of Blood and Marrow Transplantation, The University of Texas M. D. Anderson Cancer Center, 1515 Holcombe Blvd, Unit 448, Houston, TX 77030, USA.
authors: Kensuke
authors: K
authors: Kojima
authors: Marina
authors: M
authors: Konopleva
authors: Ismael J
authors: IJ
authors: Samudio
authors: Masato
authors: M
authors: Shikami
authors: Maria
authors: M
authors: Cabreira-Hansen
authors: Teresa
authors: T
authors: McQueen
authors: Vivian
authors: V
authors: Ruvolo
authors: Twee
authors: T
authors: Tsao
authors: Zhihong
authors: Z
authors: Zeng
authors: Lyubomir T
authors: LT
authors: Vassilev
authors: Michael
authors: M
authors: Andreeff
mesh_terms: D000328:Adult; D000368:Aged; D017209:Apoptosis / Q000187:drug effects*; D020169:Caspases / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D004317:Doxorubicin / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D005260:Female; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology*; D015470:Leukemia, Myeloid, Acute / Q000378:metabolism* / Q000473:pathology* / Q000628:therapy; D008297:Male; D008875:Middle Aged; D010879:Piperazines / Q000494:pharmacology*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D051736:Proto-Oncogene Proteins c-mdm2 / Q000037:antagonists & inhibitors* / Q000378:metabolism; D014407:Tumor Cells, Cultured; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*
chemical_list: D007093:Imidazoles; D010879:Piperazines; D019253:Proto-Oncogene Proteins c-bcl-2; D016159:Tumor Suppressor Protein p53; C482205:nutlin 3; D004317:Doxorubicin; D051736:Proto-Oncogene Proteins c-mdm2; D020169:Caspases