title: D-penicillamine combined with inhibitors of hydroperoxide metabolism enhances lung and breast cancer cell responses to radiation and carboplatin via H2O2-mediated oxidative stress.
abstract: D-penicillamine (DPEN), a copper chelator, has been used in the treatment of Wilson's disease, cystinuria, and rheumatoid arthritis. Recent evidence suggests that DPEN in combination with biologically relevant copper (Cu) concentrations generates H2O2in cancer cell cultures, but the effects of this on cancer cell responses to ionizing radiation and chemotherapy are unknown. Increased steady-state levels of H2O2were detected in MB231 breast and H1299 lung cancer cells following treatment with DPEN (100µM) and copper sulfate (15µM). Clonogenic survival demonstrated that DPEN-induced cancer cell toxicity was dependent on Cu and was significantly enhanced by depletion of glutathione [using buthionine sulfoximine (BSO)] as well as inhibition of thioredoxin reductase [using Auranofin (Au)] prior to exposure. Treatment with catalase inhibited DPEN toxicity confirming H2O2as the toxic species. Furthermore, pretreating cancer cells with iron sucrose enhanced DPEN toxicity while treating with deferoxamine, an Fe chelator that inhibits redox cycling, inhibited DPEN toxicity. Importantly, DPEN also demonstrated selective toxicity in human breast and lung cancer cells, relative to normal untransformed human lung or mammary epithelial cells and enhanced cancer cell killing when combined with ionizing radiation or carboplatin. Consistent with the selective cancer cell toxicity, normal untransformed human lung epithelial cells had significantly lower labile iron pools than lung cancer cells. These results support the hypothesis that DPEN mediates selective cancer cell killing as well as radio-chemo-sensitization by a mechanism involving metal ion catalyzed H2O2-mediated oxidative stress and suggest that DPEN could be repurposed as an adjuvant in conventional cancer therapy.
authors.affiliation: Free Radical and Radiation Biology Program, Department of Radiation Oncology, Holden Comprehensive Cancer Center, Carver College of Medicine, The University of Iowa, Iowa City, IA 52242, United States.
authors.forename: Sebastian J
authors.initials: SJ
authors.lastname: Sciegienka
authors.affiliation: Free Radical and Radiation Biology Program, Department of Radiation Oncology, Holden Comprehensive Cancer Center, Carver College of Medicine, The University of Iowa, Iowa City, IA 52242, United States.
authors.forename: Shane R
authors.initials: SR
authors.lastname: Solst
authors.affiliation: Free Radical and Radiation Biology Program, Department of Radiation Oncology, Holden Comprehensive Cancer Center, Carver College of Medicine, The University of Iowa, Iowa City, IA 52242, United States.
authors.forename: Kelly C
authors.initials: KC
authors.lastname: Falls
authors.affiliation: Free Radical and Radiation Biology Program, Department of Radiation Oncology, Holden Comprehensive Cancer Center, Carver College of Medicine, The University of Iowa, Iowa City, IA 52242, United States.
authors.forename: Joshua D
authors.initials: JD
authors.lastname: Schoenfeld
authors.affiliation: Free Radical and Radiation Biology Program, Department of Radiation Oncology, Holden Comprehensive Cancer Center, Carver College of Medicine, The University of Iowa, Iowa City, IA 52242, United States.
authors.forename: Adrienne R
authors.initials: AR
authors.lastname: Klinger
authors.affiliation: Free Radical and Radiation Biology Program, Department of Radiation Oncology, Holden Comprehensive Cancer Center, Carver College of Medicine, The University of Iowa, Iowa City, IA 52242, United States.
authors.forename: Natalie L
authors.initials: NL
authors.lastname: Ross
authors.affiliation: Free Radical and Radiation Biology Program, Department of Radiation Oncology, Holden Comprehensive Cancer Center, Carver College of Medicine, The University of Iowa, Iowa City, IA 52242, United States.
authors.forename: Samuel N
authors.initials: SN
authors.lastname: Rodman
authors.affiliation: Free Radical and Radiation Biology Program, Department of Radiation Oncology, Holden Comprehensive Cancer Center, Carver College of Medicine, The University of Iowa, Iowa City, IA 52242, United States.
authors.forename: Douglas R
authors.initials: DR
authors.lastname: Spitz
authors.affiliation: Free Radical and Radiation Biology Program, Department of Radiation Oncology, Holden Comprehensive Cancer Center, Carver College of Medicine, The University of Iowa, Iowa City, IA 52242, United States. Electronic address: melissa-fath@uiowa.edu.
authors.forename: Melissa A
authors.initials: MA
authors.lastname: Fath
mesh_terms: D000971:Antineoplastic Combined Chemotherapy Protocols / Q000494:pharmacology*; D001310:Auranofin / Q000494:pharmacology; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000473:pathology / Q000532:radiotherapy; D019328:Buthionine Sulfoximine / Q000494:pharmacology; D016190:Carboplatin / Q000494:pharmacology; D002374:Catalase / Q000378:metabolism; D045744:Cell Line, Tumor; D002614:Chelating Agents / Q000494:pharmacology*; D003300:Copper / Q000737:chemistry / Q000378:metabolism; D004847:Epithelial Cells / Q000187:drug effects* / Q000502:physiology; D005260:Female; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism; D008175:Lung Neoplasms / Q000188:drug therapy* / Q000473:pathology / Q000532:radiotherapy; D018384:Oxidative Stress; D010396:Penicillamine / Q000494:pharmacology*; D011827:Radiation; D013880:Thioredoxin-Disulfide Reductase / Q000037:antagonists & inhibitors
chemical_list: D002614:Chelating Agents; D001310:Auranofin; D019328:Buthionine Sulfoximine; D003300:Copper; D006861:Hydrogen Peroxide; D016190:Carboplatin; D002374:Catalase; D013880:Thioredoxin-Disulfide Reductase; D010396:Penicillamine
keywords: Breast cancer; D-penicillamine; Hydrogen peroxide; Lung cancer; Oxidative metabolism; Transition metal ions