title: Overexpression of 15-lipoxygenase-1 induces growth arrest through phosphorylation of p53 in human colorectal cancer cells.
abstract: To investigate the function of 15-lipoxygenase-1 (15-LOX-1) in human colorectal cancer, we overexpressed 15-LOX-1 in HCT-116 human colorectal cancer cells. Clones expressing the highest levels of 15-LOX-1 displayed reduced viability compared with the HCT-116-Vector control cells. Further, by cell cycle gene array analyses, the cyclin-dependent kinase inhibitor p21WAF1/CIP1 and MDM2 genes were up-regulated in 15-LOX-1-overexpressing cells. The induction of p21(WAF1/CIP1) and MDM2 were linked to activation of p53 by 15-LOX-1, as there was a dramatic induction of phosphorylated p53 (Ser15) in 15-LOX-1-overesxpressing cells. However, the 15-LOX-1 metabolites 13(S)-hydroxyoctadecadienoic acid and 15(S)-hydroxyeicosatetraenoic acid failed to induce phosphorylation of p53 at Ser15, and the 15-LOX-1 inhibitor PD146176 did not inhibit the phosphorylation of p53 at Ser15 in 15-LOX-1-overexpressing cells. Nonetheless, the growth-inhibitory effects of 15-LOX-1 were p53 dependent, as 15-LOX-1 overexpression had no effect on cell growth in p53 (-/-) HCT-116 cells. Finally, treatment of HCT-116-15-LOX-1 cells with different kinase inhibitors suggested that the effects of 15-LOX-1 on p53 phosphorylation and activation were due to effects on DNA-dependent protein kinase. Collectively, these findings suggest a new mechanism to explain the biological activity of 15-LOX-1, where 15-LOX plays a stoichiometric role in activating a DNA-dependent protein kinase-dependent pathway that leads to p53-dependent growth arrest.
authors.affiliation: Laboratory of Molecular Carcinogenesis, National Institute of Environmental Health Sciences, NIH, MD, USA.
authors.forename: Jong-Sik
authors.initials: JS
authors.lastname: Kim
authors.forename: Seung Joon
authors.initials: SJ
authors.lastname: Baek
authors.forename: Frank G
authors.initials: FG
authors.lastname: Bottone
authors.forename: Tina
authors.initials: T
authors.lastname: Sali
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Eling
mesh_terms: D001093:Arachidonate 15-Lipoxygenase / Q000378:metabolism*; D018797:Cell Cycle Proteins / Q000378:metabolism; D002455:Cell Division; D015179:Colorectal Neoplasms / Q000378:metabolism* / Q000473:pathology*; D050759:Cyclin-Dependent Kinase Inhibitor p21; D051747:DNA-Activated Protein Kinase; D004268:DNA-Binding Proteins / Q000494:pharmacology; D015118:Eicosapentaenoic Acid / Q000031:analogs & derivatives / Q000378:metabolism; D015972:Gene Expression Regulation, Neoplastic; D045325:HCT116 Cells; D006801:Humans; D008041:Linoleic Acids / Q000378:metabolism; D016859:Lipoxygenase Inhibitors / Q000494:pharmacology; D009687:Nuclear Proteins / Q000378:metabolism; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000494:pharmacology; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051736:Proto-Oncogene Proteins c-mdm2; D014407:Tumor Cells, Cultured; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*
chemical_list: C493956:CDKN1A protein, human; D018797:Cell Cycle Proteins; D050759:Cyclin-Dependent Kinase Inhibitor p21; D004268:DNA-Binding Proteins; D008041:Linoleic Acids; D016859:Lipoxygenase Inhibitors; D009687:Nuclear Proteins; D011518:Proto-Oncogene Proteins; D016159:Tumor Suppressor Protein p53; C024348:13-hydroxy-9,11-octadecadienoic acid; C059164:15-hydroxy-5,8,11,13,17-eicosapentaenoic acid; D015118:Eicosapentaenoic Acid; D001093:Arachidonate 15-Lipoxygenase; C497206:MDM2 protein, human; D051736:Proto-Oncogene Proteins c-mdm2; D051747:DNA-Activated Protein Kinase; C497263:PRKDC protein, human; D017346:Protein Serine-Threonine Kinases