Activation of the p53 pathway by the MDM2 inhibitor nutlin-3a overcomes BCL2 overexpression in a preclinical model of diffuse large B-cell lymphoma associated with t(14;18)(q32;q21)

Leukemia. 2011 May;25(5):856-67. doi: 10.1038/leu.2011.28. Epub 2011 Mar 11.

Abstract

p53 is frequently wild type (wt) in diffuse large B-cell lymphoma (DLBCL) associated with t(14;18)(q32;q21) that overexpresses BCL2. Nutlin-3a is a small molecule that activates the p53 pathway by disrupting p53-MDM2 interaction. We show that nutlin-3a activates p53 in DLBCL cells associated with t(14;18)(q32;q21), BCL2 overexpression and wt p53, resulting in cell cycle arrest and apoptosis. Nutlin-3a treatment had similar effects on DLBCL cells of activated B-cell phenotype with wt p53. Cell cycle arrest was associated with upregulation of p21. Nutlin-3a-induced apoptosis was accompanied by BAX and PUMA upregulation, BCL-XL downregulation, serine-70 dephosphorylation of BCL2, direct binding of BCL2 by p53, caspase-9 upregulation and caspase-3 cleavage. Cell death was reduced when p53-dependent transactivation activity was inhibited by pifithrin-α (PFT-α), or PFT-μ inhibited direct p53 targeting of mitochondria. Nutlin-3a sensitized activation of the intrinsic apoptotic pathway by BCL2 inhibitors in t(14;18)-positive DLBCL cells with wt p53, and enhanced doxorubicin cytotoxicity against t(14;18)-positive DLBCL cells with wt or mutant p53, the latter in part via p73 upregulation. Nutlin-3a treatment in a xenograft animal lymphoma model inhibited growth of t(14;18)-positive DLBCL tumors, associated with increased apoptosis and decreased proliferation. These data suggest that disruption of the p53-MDM2 interaction by nutlin-3a offers a novel therapeutic approach for DLBCL associated with t(14;18)(q32;q21).

MeSH terms

  • Animals
  • Antineoplastic Agents / pharmacology
  • Apoptosis
  • Blotting, Western
  • Cell Cycle
  • Cell Proliferation
  • Chromosomes, Human, Pair 14 / genetics*
  • Chromosomes, Human, Pair 18 / genetics*
  • Disease Models, Animal
  • Female
  • Fluorescent Antibody Technique
  • Humans
  • Imidazoles / pharmacology*
  • Immunoprecipitation
  • Lymphoma, Large B-Cell, Diffuse / drug therapy
  • Lymphoma, Large B-Cell, Diffuse / genetics
  • Lymphoma, Large B-Cell, Diffuse / metabolism*
  • Mice
  • Mice, SCID
  • Mutation / genetics
  • Piperazines / pharmacology*
  • Proto-Oncogene Proteins c-bcl-2 / genetics
  • Proto-Oncogene Proteins c-bcl-2 / metabolism*
  • Proto-Oncogene Proteins c-mdm2 / antagonists & inhibitors*
  • Proto-Oncogene Proteins c-mdm2 / genetics
  • Proto-Oncogene Proteins c-mdm2 / metabolism
  • RNA, Messenger / genetics
  • Reverse Transcriptase Polymerase Chain Reaction
  • Signal Transduction
  • Translocation, Genetic / genetics*
  • Tumor Cells, Cultured
  • Tumor Suppressor Protein p53 / genetics
  • Tumor Suppressor Protein p53 / metabolism*
  • Xenograft Model Antitumor Assays

Substances

  • Antineoplastic Agents
  • Imidazoles
  • Piperazines
  • Proto-Oncogene Proteins c-bcl-2
  • RNA, Messenger
  • Tumor Suppressor Protein p53
  • nutlin 3
  • Proto-Oncogene Proteins c-mdm2