title: The chemopreventive agent N-(4-hydroxyphenyl)retinamide induces apoptosis through a mitochondrial pathway regulated by proteins from the Bcl-2 family.
abstract: N-(4-hydroxyphenyl)retinamide (4-HPR, fenretinide) is a potent chemopreventive agent whose effect has been suggested to involve apoptosis induction. 4-HPR induces a loss of the mitochondrial transmembrane potential and the mitochondrial release of cytochrome c before caspase activation. Inhibition of mitochondrial membrane permeabilization (MMP) by transfection with Bcl-2 or the Cytomegalovirus UL37 gene product vMIA prevented caspase activation and cell death. In contrast to other retinoid derivatives, 4-HPR has no direct MMP-inducing effects when added to isolated mitochondria or when added to proteoliposomes containing the MMP-regulatory permeability transition pore complex (PTPC). Moreover, although reactive oxygen species (ROS) overproduction appears to be instrumental for 4-HPR-induced MMP and apoptosis, inhibition of the NF-kappaB or p53-mediated signal transduction pathways failed to modulate 4-HPR-induced apoptosis. 4-HPR was found to cause an antioxidant-inhibitable conformational change of both Bax and Bak, leading to the exposure of their N-termini and to the mitochondrial relocalization of Bax. Cells with a Bax(-/-) Bak(-/-) genotype were resistant against the 4-HPR-induced MMP, overproduction of ROS and cell death. Altogether, these data indicate that 4-HPR induces MMP through an ROS-mediated pathway that involves the obligatory contribution of the proapopotic Bcl-2 family members Bax and/or Bak.
mesh_terms: D016588:Anticarcinogenic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism; D003574:Cytochrome c Group / Q000187:drug effects; D004789:Enzyme Activation / Q000187:drug effects; D017313:Fenretinide / Q000494:pharmacology*; D006367:HeLa Cells; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism*; D010539:Permeability / Q000187:drug effects; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D014407:Tumor Cells, Cultured; D050998:bcl-2 Homologous Antagonist-Killer Protein; D051028:bcl-2-Associated X Protein
chemical_list: D016588:Anticarcinogenic Agents; C494772:BAK1 protein, human; C494826:BAX protein, human; D061945:Caspase Inhibitors; D003574:Cytochrome c Group; D008565:Membrane Proteins; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D050998:bcl-2 Homologous Antagonist-Killer Protein; D051028:bcl-2-Associated X Protein; D017313:Fenretinide; D020169:Caspases