title: Radiation-induced up-regulation of Mmp2 involves increased mRNA stability, redox modulation, and MAPK activation.
abstract: We have previously observed time- and dose-dependent increases in matrix metalloproteinase 2 (Mmp2) protein levels in rat tubule epithelial cells (NRK52E) after irradiation. However, the mechanism(s) involved remains unclear. In the present study, irradiating NRK52E cells with 0-20 Gy gamma rays was associated with time- and dose-dependent increases in Mmp2 mRNA. Studies using the transcription inhibitor actinomycin D (ActD) added 24 h after irradiation revealed the t(1/2) of Mmp2 mRNA to be approximately 8 h in control cells. In contrast, the increase in Mmp2 mRNA levels in irradiated cells was essentially unchanged after incubation with ActD for up to 12 h. Incubating cells with the antioxidants N-acetylcysteine or ebselen or the MEK pathway inhibitors PD98059 and U0126 prior to irradiation abolished the radiation-induced up-regulation of Mmp2. Irradiating NRK52E cells led to reactive oxygen species-mediated Erk1/2 activation; preincubation with NAC prevented the radiation-induced increase in phosphorylated Erk1/2. Transfecting cells with a dominant-negative ERK mutant completely inhibited radiation-induced Erk phosphorylation and abolished the radiation-induced up-regulation of Mmp2 protein. Thus the radiation-induced up-regulation of Mmp2 mRNA is due in part to increased mRNA stability and is mediated by redox; the ERK MAPK signaling pathway may be involved.
authors.affiliation: Department of Radiation Oncology, Brain Tumor Center of Wake Forest University, Wake Forest University School of Medicine, Winston-Salem, North Carolina 27157, USA. wzhao@wfubmc.edu
authors.forename: Weiling
authors.initials: W
authors.lastname: Zhao
authors.forename: Prabhat C
authors.initials: PC
authors.lastname: Goswami
authors.forename: Mike E C
authors.initials: ME
authors.lastname: Robbins
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D015152:Blotting, Northern; D015153:Blotting, Western; D002070:Butadienes / Q000494:pharmacology; D002460:Cell Line; D002478:Cells, Cultured; D018076:DNA, Complementary / Q000378:metabolism; D003609:Dactinomycin / Q000494:pharmacology; D004307:Dose-Response Relationship, Radiation; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004847:Epithelial Cells / Q000378:metabolism; D005419:Flavonoids / Q000494:pharmacology; D005799:Genes, Dominant; D007684:Kidney Tubules / Q000166:cytology; D007700:Kinetics; D020935:MAP Kinase Signaling System; D020778:Matrix Metalloproteinase 2 / Q000096:biosynthesis*; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009154:Mutation; D009570:Nitriles / Q000494:pharmacology; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D010766:Phosphorylation; D011691:Puromycin / Q000494:pharmacology; D012313:RNA / Q000737:chemistry; D012333:RNA, Messenger / Q000528:radiation effects*; D051381:Rats; D015398:Signal Transduction; D013997:Time Factors; D014162:Transfection; D015854:Up-Regulation
chemical_list: D000975:Antioxidants; D002070:Butadienes; D018076:DNA, Complementary; D004791:Enzyme Inhibitors; D005419:Flavonoids; D009570:Nitriles; D012333:RNA, Messenger; C113580:U 0126; D003609:Dactinomycin; D011691:Puromycin; D012313:RNA; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D020778:Matrix Metalloproteinase 2; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one