title: Knockdown of ornithine decarboxylase antizyme 1 causes loss of uptake regulation leading to increased N1, N11-bis(ethyl)norspermine (BENSpm) accumulation and toxicity in NCI H157 lung cancer cells.
abstract: Ornithine decarboxylase antizyme 1 (AZ1) is a major regulatory protein responsible for the regulation and degradation of ornithine decarboxylase (ODC). To better understand the role of AZ1 in polyamine metabolism and in modulating the response to anticancer polyamine analogues, a small interfering RNA strategy was used to create a series of stable clones in human H157 non-small cell lung cancer cells that expressed less than 5-10% of basal AZ1 levels. Antizyme 1 knockdown clones accumulated greater amounts of the polyamine analogue N (1),N (11)-bis(ethyl)norspermine (BENSpm) and were more sensitive to analogue treatment. The possibility of a loss of polyamine uptake regulation in the knockdown clones was confirmed by polyamine uptake analysis. These results are consistent with the hypothesis that AZ1 knockdown leads to dysregulation of polyamine uptake, resulting in increased analogue accumulation and toxicity. Importantly, there appears to be little difference between AZ1 knockdown cells and cells with normal levels of AZ1 with respect to ODC regulation, suggesting that another regulatory protein, potentially AZ2, compensates for the loss of AZ1. The results of these studies are important for the understanding of both the regulation of polyamine homeostasis and in understanding the factors that regulate tumor cell sensitivity to the anti-tumor polyamine analogues.
authors.affiliation: Department of Oncology, The Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Bunting-Blaustein Cancer Research Building 1, 1650 Orleans Street, Baltimore, MD 21231, USA.
authors.forename: Alison V
authors.initials: AV
authors.lastname: Fraser
authors.forename: Andrew C
authors.initials: AC
authors.lastname: Goodwin
authors.forename: Amy
authors.initials: A
authors.lastname: Hacker-Prietz
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Sugar
authors.forename: Patrick M
authors.initials: PM
authors.lastname: Woster
authors.forename: Robert A
authors.initials: RA
authors.lastname: Casero
mesh_terms: D001483:Base Sequence; D015152:Blotting, Northern; D045744:Cell Line, Tumor; D055785:Gene Knockdown Techniques; D006801:Humans; D008175:Lung Neoplasms / Q000201:enzymology / Q000378:metabolism* / Q000473:pathology; D008969:Molecular Sequence Data; D011073:Polyamines / Q000378:metabolism; D011506:Proteins / Q000235:genetics / Q000378:metabolism*; D034741:RNA, Small Interfering; D013096:Spermine / Q000031:analogs & derivatives* / Q000378:metabolism / Q000633:toxicity
chemical_list: D011073:Polyamines; D011506:Proteins; D034741:RNA, Small Interfering; C031017:ornithine decarboxylase antizyme; C059685:N(1),N(11)-diethylnorspermine; D013096:Spermine