title: Selective targeting of c-Abl via a cryptic mitochondrial targeting signal activated by cellular redox status in leukemic and breast cancer cells.
abstract: OBJECTIVE
  The tyrosine kinase c-Abl localizes to the mitochondria under cell stress conditions and promotes apoptosis. However, c-Abl has not been directly targeted to the mitochondria. Fusing c-Abl to a mitochondrial translocation signal (MTS) that is activated by reactive oxygen species (ROS) will selectively target the mitochondria of cancer cells exhibiting an elevated ROS phenotype. Mitochondrially targeted c-Abl will thereby induce malignant cell death.
  
  
  METHODS
  Confocal microscopy was used to determine mitochondrial colocalization of ectopically expressed c-Abl-EGFP/cMTS fusion across three cell lines (K562, Cos-7, and 1471.1) with varying levels of basal (and pharmacologically modulated) ROS. ROS were quantified by indicator dye assay. The functional consequences of mitochondrial c-Abl were assessed by DNA accessibility to 7-AAD using flow cytometry.
  
  
  RESULTS
  The cMTS and cMTS/c-Abl fusions colocalized to the mitochondria in leukemic (K562) and breast (1471.1) cancer phenotypes (but not Cos-7 fibroblasts) in a ROS and PKC dependent manner.
  
  
  CONCLUSIONS
  We confirm and extend oxidative stress activated translocation of the cMTS by demonstrating that the cMTS and Abl/cMTS fusion selectively target the mitochondria of K562 leukemia and mammary adenocarcinoma 1471.1 cells. c-Abl induced K562 leukemia cell death when targeted to the matrix but not the outer membrane of the mitochondria.
authors.affiliation: Department of Pharmacology and Toxicology, College of Pharmacy, University of Utah, Salt Lake City, Utah 84108, USA. Jonathan.Constance@utah.edu
authors.forename: Jonathan E
authors.initials: JE
authors.lastname: Constance
authors.forename: Samuel D
authors.initials: SD
authors.lastname: Despres
authors.forename: Akemi
authors.initials: A
authors.lastname: Nishida
authors.forename: Carol S
authors.initials: CS
authors.lastname: Lim
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D019556:COS Cells; D016923:Cell Death; D045744:Cell Line, Tumor; D002522:Chlorocebus aethiops; D005260:Female; D015870:Gene Expression; D006801:Humans; D007938:Leukemia / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D015674:Mammary Neoplasms, Animal / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D051379:Mice; D008928:Mitochondria / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D008969:Molecular Sequence Data; D018384:Oxidative Stress; D021381:Protein Transport; D016315:Proto-Oncogene Proteins c-abl / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism
chemical_list: D017382:Reactive Oxygen Species; D011993:Recombinant Fusion Proteins; D016315:Proto-Oncogene Proteins c-abl