title: p53 Phosphorylation at serine 15 is required for transcriptional induction of the plasminogen activator inhibitor-1 (PAI-1) gene by the alkylating agent N-methyl-N'-nitro-N-nitrosoguanidine.
abstract: The alkylating agent N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) is a widely spread environmental carcinogen that causes DNA lesions leading to cell killing. MNNG can also induce a cell-protective response by inducing the expression of DNA repair/transcription-related genes. We recently demonstrated that urokinase-type plasminogen activator, an extracellular protease to which no DNA repair functions have been assigned, was induced by MNNG. Here, we show that the physiological inhibitor of urokinase-type plasminogen activator, PAI-1, is also induced by MNNG in a p53-dependent fashion, because MNNG induced PAI-1 in p53-expressing cells but not in p53-/- cells. MNNG induced p53 phosphorylation at serine 15, resulting in stabilization of the p53 protein, and this phosphorylation event was central for p53-dependent PAI-1 transcription. Finally, we showed that PAI-1 transcriptional induction by MNNG required a p53-responsive element located at -136 base pairs in the PAI-1 promoter, because specific mutation of this site abrogated the induction. Because PAI-1 is a prognostic factor in many metastatic cancers, being involved in the control of tumor invasiveness, our finding that a genotoxic agent induces the PAI-1 gene via p53 adds a new feature to the role of the tumor-suppressor p53 protein. Our results also suggest the possibility that genotoxic agents contribute to tumor metastasis by inducing PAI-1 without involving genetic modification.
authors.affiliation: Institut de Recerca Oncologica, Center d'Oncologia Molecular, Aut. Castelldefels, km 2.7, L'Hospitalet Ll., E-08907 Barcelona, Spain.
authors.forename: M
authors.initials: M
authors.lastname: Parra
authors.forename: M
authors.initials: M
authors.lastname: Jardí
authors.forename: M
authors.initials: M
authors.lastname: Koziczak
authors.forename: Y
authors.initials: Y
authors.lastname: Nagamine
authors.forename: P
authors.initials: P
authors.lastname: Muñoz-Cánoves
mesh_terms: D016475:3T3 Cells; D000477:Alkylating Agents / Q000494:pharmacology*; D000818:Animals; D015152:Blotting, Northern; D015153:Blotting, Western; D016158:Genes, p53; D008769:Methylnitronitrosoguanidine / Q000494:pharmacology*; D051379:Mice; D009154:Mutation; D010766:Phosphorylation; D010957:Plasmids; D017395:Plasminogen Activator Inhibitor 1 / Q000737:chemistry* / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D014162:Transfection; D016159:Tumor Suppressor Protein p53 / Q000737:chemistry / Q000378:metabolism*
chemical_list: D000477:Alkylating Agents; D017395:Plasminogen Activator Inhibitor 1; D016159:Tumor Suppressor Protein p53; D008769:Methylnitronitrosoguanidine