title: Mechanisms of Doxorubicin Toxicity in Pancreatic β-Cells.
abstract: Exposure to chemotherapeutic agents has been linked to an increased risk of type 2 diabetes (T2D), a disease characterized by both the peripheral insulin resistance and impaired glucose-stimulated insulin secretion (GSIS) from pancreatic β-cells. Using the rat β-cell line INS-1 832/13 and isolated mouse pancreatic islets, we investigated the effect of the chemotherapeutic drug doxorubicin (Adriamycin) on pancreatic β-cell survival and function. Exposure of INS-1 832/13 cells to doxorubicin caused impairment of GSIS, cellular viability, an increase in cellular toxicity, as soon as 6 h post-exposure. Doxorubicin impaired plasma membrane electron transport (PMET), a pathway dependent on reduced equivalents NADH and NADPH, but failed to redox cycle in INS-1 832/13 cells and with their lysates. Although NADPH/NADP(+ )content was unaffected, NADH/NAD(+ )content decreased at 4 h post-exposure to doxorubicin, and was followed by a reduction in ATP content. Previous studies have demonstrated that doxorubicin functions as a topoisomerase II inhibitor via induction of DNA cross-linking, resulting in apoptosis. Doxorubicin induced the expression of mRNA for mdm2, cyclin G1, and fas whereas downregulating p53, and increased the melting temperature of genomic DNA, consistent with DNA damage and induction of apoptosis. Doxorubicin also induced caspase-3 and -7 activity in INS-1 832/13 cells and mouse islets; co-treatment with the pan-caspase inhibitor Z-VAD-FMK temporarily attenuated the doxorubicin-mediated loss of viability in INS-1 832/13 cells. Together, these data suggest that DNA damage, not H2O2 produced via redox cycling, is a major mechanism of doxorubicin toxicity in pancreatic β-cells.
authors.affiliation: *Department of Molecular Pharmacology and Physiology, Morsani College of Medicine, University of South Florida, Tampa, Florida 33612.
authors.forename: Emma A
authors.initials: EA
authors.lastname: Heart
authors.affiliation: *Department of Molecular Pharmacology and Physiology, Morsani College of Medicine, University of South Florida, Tampa, Florida 33612.
authors.forename: Shpetim
authors.initials: S
authors.lastname: Karandrea
authors.affiliation: *Department of Molecular Pharmacology and Physiology, Morsani College of Medicine, University of South Florida, Tampa, Florida 33612.
authors.forename: Xiaomei
authors.initials: X
authors.lastname: Liang
authors.affiliation: Department of Science, United States Coast Guard Academy, New London, Connecticut 06320.
authors.forename: Maren E
authors.initials: ME
authors.lastname: Balke
authors.affiliation: Department of Science, United States Coast Guard Academy, New London, Connecticut 06320.
authors.forename: Patrick A
authors.initials: PA
authors.lastname: Beringer
authors.affiliation: Department of Science, United States Coast Guard Academy, New London, Connecticut 06320.
authors.forename: Elyse M
authors.initials: EM
authors.lastname: Bobczynski
authors.affiliation: University of Puerto Rico at Cayey, Cayey, Puerto Rico 00736;
authors.forename: Delaine
authors.initials: D
authors.lastname: Zayas-Bazán Burgos
authors.affiliation: Princeton University, Princeton, New Jersey, 08544.
authors.forename: Tiffany
authors.initials: T
authors.lastname: Richardson
authors.affiliation: *Department of Molecular Pharmacology and Physiology, Morsani College of Medicine, University of South Florida, Tampa, Florida 33612 Department of Science, United States Coast Guard Academy, New London, Connecticut 06320 Joshua.p.gray@uscga.edu.
authors.forename: Joshua P
authors.initials: JP
authors.lastname: Gray
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D002460:Cell Line; D004249:DNA Damage; D003920:Diabetes Mellitus / Q000139:chemically induced; D004317:Doxorubicin / Q000633:toxicity*; D007328:Insulin / Q000378:metabolism; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D051381:Rats
chemical_list: D007328:Insulin; D004317:Doxorubicin
keywords: Adriamycin; NAD(P)H; doxorubicin; insulin secretion; pancreatic β-cell; redox cycling