title: Targeting lysosomal degradation induces p53-dependent cell death and prevents cancer in mouse models of lymphomagenesis.
abstract: Despite great interest in cancer chemoprevention, effective agents are few. Here we show that chloroquine, a drug that activates the stress-responsive Atm-p53 tumor-suppressor pathway, preferentially enhances the death of Myc oncogene-overexpressing primary mouse B cells and mouse embryonic fibroblasts (MEFs) and impairs Myc-induced lymphomagenesis in a transgenic mouse model of human Burkitt lymphoma. Chloroquine-induced cell death in primary MEFs and human colorectal cancer cells was dependent upon p53, but not upon the p53 modulators Atm or Arf. Accordingly, chloroquine impaired spontaneous lymphoma development in Atm-deficient mice, a mouse model of ataxia telangiectasia, but not in p53-deficient mice. Chloroquine treatment enhanced markers of both macroautophagy and apoptosis in MEFs but ultimately impaired lysosomal protein degradation. Interestingly, chloroquine-induced cell death was not dependent on caspase-mediated apoptosis, as neither overexpression of the antiapoptotic protein Bcl-2 nor deletion of the proapoptotic Bax and Bak affected chloroquine-induced MEF death. However, when both apoptotic and autophagic pathways were blocked simultaneously, chloroquine-induced killing of Myc-overexpressing cells was blunted. Thus chloroquine induces lysosomal stress and provokes a p53-dependent cell death that does not require caspase-mediated apoptosis. These findings specifically demonstrate that intermittent chloroquine use effectively prevents cancer in mouse models of 2 genetically distinct human cancer syndromes, Burkitt lymphoma and ataxia telangiectasia, suggesting that agents targeting lysosome-mediated degradation may be effective in cancer prevention.
authors: Division of Molecular Therapeutics, Department of Oncology, St. Jude Children's Research Hospital, Memphis, Tennessee 38105, USA.
authors: Kirsteen H
authors: KH
authors: Maclean
authors: Frank C
authors: FC
authors: Dorsey
authors: John L
authors: JL
authors: Cleveland
authors: Michael B
authors: MB
authors: Kastan
mesh_terms: D000818:Animals; D018501:Antirheumatic Agents / Q000494:pharmacology* / Q000627:therapeutic use; D017209:Apoptosis / Q000187:drug effects* / Q000235:genetics; D001260:Ataxia Telangiectasia / Q000235:genetics / Q000378:metabolism / Q000473:pathology / Q000517:prevention & control*; D064007:Ataxia Telangiectasia Mutated Proteins; D001343:Autophagy / Q000187:drug effects* / Q000235:genetics; D001402:B-Lymphocytes / Q000378:metabolism / Q000473:pathology; D002051:Burkitt Lymphoma / Q000235:genetics / Q000378:metabolism / Q000473:pathology / Q000517:prevention & control*; D020169:Caspases / Q000235:genetics / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism; D002471:Cell Transformation, Neoplastic / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D002478:Cells, Cultured; D002738:Chloroquine / Q000494:pharmacology* / Q000627:therapeutic use; D019941:Cyclin-Dependent Kinase Inhibitor p16 / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D004622:Embryo, Mammalian / Q000378:metabolism / Q000473:pathology; D005260:Female; D005347:Fibroblasts / Q000378:metabolism / Q000473:pathology; D006801:Humans; D008247:Lysosomes / Q000378:metabolism* / Q000473:pathology; D008297:Male; D051379:Mice; D008817:Mice, Mutant Strains; D009374:Neoplasms, Experimental / Q000235:genetics / Q000378:metabolism / Q000473:pathology / Q000517:prevention & control; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism; D016271:Proto-Oncogene Proteins c-myc / Q000235:genetics / Q000378:metabolism; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism*; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000378:metabolism; D050998:bcl-2 Homologous Antagonist-Killer Protein / Q000235:genetics / Q000378:metabolism; D051028:bcl-2-Associated X Protein / Q000235:genetics / Q000378:metabolism
chemical_list: D018501:Antirheumatic Agents; C494773:Bak1 protein, mouse; C494827:Bax protein, mouse; C417743:Cdkn2a protein, mouse; D018797:Cell Cycle Proteins; D019941:Cyclin-Dependent Kinase Inhibitor p16; D004268:DNA-Binding Proteins; D016271:Proto-Oncogene Proteins c-myc; D016159:Tumor Suppressor Protein p53; D025521:Tumor Suppressor Proteins; D050998:bcl-2 Homologous Antagonist-Killer Protein; D051028:bcl-2-Associated X Protein; D002738:Chloroquine; C576324:ATM protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; C576325:Atm protein, mouse; D017346:Protein Serine-Threonine Kinases; D020169:Caspases