title: Overexpression of Prdx6 and resistance to peroxide-induced death in Hepa1-6 cells: Prdx suppression increases apoptosis.
abstract: Peroxiredoxins are thiol-specific antioxidants that catalyze the reduction of cellular peroxides and protect cells from ROS-mediated damage and death. Peroxiredoxin gene expression is up-regulated in a number of cancers, suggesting a possible role in cancer cell maintenance. Prdx6, a cytoplasmic protein elevated in certain cancers, is highly expressed in liver and transcriptionally regulated by various oxidative stresses. In the present study, we found that the cancerous Hepa1-6 hepatoma cell line is significantly more resistant to peroxide-induced cytotoxicity than the non-cancerous H2.35 cell line. We also demonstrated that Hepa1-6 cells express approximately 3-fold more Prdx6 mRNA and 2.5-fold more Prdx6 protein than H2.35 cells. Treatment with mithramycin A resulted in a nearly 20% reduction in Prdx6 mRNA in Hepa1-6 cells, suggesting a possible role for Sp1 in Prdx6 up-regulation. We hypothesized that suppression of Prdx6 in Hepa1-6 cells would increase susceptibility to peroxide-induced cell death. Transient transfection of Hepa1-6 cells with Prdx6 siRNA led to a marked reduction in Prdx6 expression, and an increase in peroxide-induced cytotoxicity by apoptosis. Together, these data demonstrate an important anti-apoptotic function for Prdx6 in cancerous liver cells, and suggest that its up-regulation may be a tumor-supportive adaptation in cancerous states.
authors.affiliation: Department of Biology, Fairfield University, Fairfield, Connecticut, USA.
authors.forename: Bridget
authors.initials: B
authors.lastname: Walsh
authors.forename: Amanda
authors.initials: A
authors.lastname: Pearl
authors.forename: Sarah
authors.initials: S
authors.lastname: Suchy
authors.forename: John
authors.initials: J
authors.lastname: Tartaglio
authors.forename: Kristin
authors.initials: K
authors.lastname: Visco
authors.forename: Shelley A
authors.initials: SA
authors.lastname: Phelan
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology; D002460:Cell Line / Q000187:drug effects; D006801:Humans; D008113:Liver Neoplasms / Q000378:metabolism / Q000473:pathology; D051379:Mice; D010545:Peroxides / Q000494:pharmacology*; D054465:Peroxiredoxin VI / Q000235:genetics / Q000378:metabolism*; D054464:Peroxiredoxins / Q000235:genetics / Q000378:metabolism; D008926:Plicamycin / Q000031:analogs & derivatives / Q000494:pharmacology; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism
chemical_list: D010545:Peroxides; D034741:RNA, Small Interfering; D017382:Reactive Oxygen Species; C066851:mithramycin A; D054465:Peroxiredoxin VI; D054464:Peroxiredoxins; D008926:Plicamycin