title: The p53-induced gene-6 (proline oxidase) mediates apoptosis through a calcineurin-dependent pathway.
abstract: Proline oxidase is a p53-induced redox gene that can generate reactive oxygen species (ROS) and mediate apoptosis in tumor cells. We report that proline oxidase is a downstream effector in p53-mediated activation of the calcium/calmodulin-dependent phosphatase calcineurin in lung, renal, colon, and ovarian carcinoma cells. The activation of calcineurin by p53 and proline oxidase was detected by activation of the nuclear factor of activated T cells (NFAT), an established indicator of activated calcineurin. Both proline oxidase- and p53-induced activation of NFAT were sensitive to the calcineurin inhibitors cyclosporin A and FK-506, to scavengers of ROS, and to inhibitors of calcium mobilization. A proline oxidase antisense vector suppressed the ability of p53 to up-regulate proline oxidase, activate calcineurin, and induce apoptosis. Moreover, two renal carcinoma-derived mutant p53 proteins were deficient in inducing proline oxidase expression and in activating calcineurin. Inhibitors of calcineurin and calcium mobilization abolished proline oxidase-mediated apoptosis and reduced p53-induced apoptosis. Treatment of colon and ovarian carcinoma cells with the anticancer genotoxic agent etoposide up-regulated both p53 and proline oxidase, activated calcineurin, and induced apoptosis. The etoposide-mediated activation of calcineurin and induction of apoptosis was markedly suppressed by FK-506 calcineurin inhibitor. We propose that proline oxidase mediates apoptosis through the generation of proline-dependent ROS, which then mobilize calcium and activate calcineurin. The activation of calcineurin-regulated transcription factor pathways by proline oxidase might affect gene expression events important to p53 regulation of cell growth and apoptosis.
authors.affiliation: Department of Pathology and Laboratory Medicine, Texas A&M University System Health Science Center, College Station, TX 77843-1114, USA.
authors.forename: Armando
authors.initials: A
authors.lastname: Rivera
authors.forename: Steve A
authors.initials: SA
authors.lastname: Maxwell
mesh_terms: D017209:Apoptosis; D015153:Blotting, Western; D019703:Calcineurin / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism; D002292:Carcinoma, Renal Cell / Q000473:pathology; D045744:Cell Line, Tumor; D016572:Cyclosporine / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004797:Enzyme-Linked Immunosorbent Assay; D005047:Etoposide / Q000494:pharmacology; D017930:Genes, Reporter; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006801:Humans; D007680:Kidney Neoplasms / Q000473:pathology; D008156:Luciferases / Q000378:metabolism; D050778:NFATC Transcription Factors; D009687:Nuclear Proteins / Q000378:metabolism; D019384:Nucleic Acid Synthesis Inhibitors / Q000494:pharmacology; D016376:Oligonucleotides, Antisense / Q000737:chemistry; D010957:Plasmids / Q000378:metabolism; D011394:Proline Oxidase / Q000235:genetics / Q000502:physiology*; D017382:Reactive Oxygen Species; D016559:Tacrolimus / Q000378:metabolism / Q000494:pharmacology; D014157:Transcription Factors / Q000378:metabolism; D014162:Transfection; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D015854:Up-Regulation
chemical_list: D004268:DNA-Binding Proteins; D050778:NFATC Transcription Factors; D009687:Nuclear Proteins; D019384:Nucleic Acid Synthesis Inhibitors; D016376:Oligonucleotides, Antisense; D017382:Reactive Oxygen Species; D014157:Transcription Factors; D016159:Tumor Suppressor Protein p53; D049452:Green Fluorescent Proteins; D005047:Etoposide; D016572:Cyclosporine; D008156:Luciferases; D011394:Proline Oxidase; D019703:Calcineurin; D002118:Calcium; D016559:Tacrolimus