title: Lazaroid compounds prevent early but not late stages of oxidant-induced cell injury: potential explanation for the lack of efficacy of lazaroids in clinical trials.
abstract: Earlier in vitro studies demonstrated the remarkable potency of the lazaroid compounds to prevent oxidant-induced early cell injury. However, the ability of lazaroid compounds to limit oxidative injury in vivo(including renal ischemia-reperfusion) has been less certain, and the early clinical trials using lazaroids to limit CNS injury or organ injury in the setting of transplantation have not been promising. Lazaroid compounds are potent inhibitors of lipid peroxidation, and their inability to influence other key injury processes, particularly during the late stages of cell injury, might partly explain the limited clinical efficacy. To test this, renal tubular (LLC-PK1) cells were incubated with 250 micromH(2)O(2)for 135 min, in the presence or absence of 2-methyl aminochroman (2-MAC, U-83836E), a lazaroid with potent ability to inhibit lipid peroxidation, or desferrioxamine, (DFO) an iron chelator with broader antioxidant efficacy. Cell injury, lipid peroxidation, DNA damage and ATP depletion were measured in the early (immediately after H(2)O(2)incubation) and late (24 h after H(2)O(2)incubation) stages of cell injury. In the early stage, 2-MAC suppressed H(2)O(2)-induced lipid peroxidation and LDH release, but not the DNA damage, ATP depletion or loss of cell replication. In contrast, DFO suppressed all of the measurements. In the late stages, despite continued suppression of lipid peroxidation, only DFO maintained significant cytoprotection against H(2)O(2), and this was accompanied by reduced DNA damage, higher ATP levels and preservation of cell proliferation. Thus, the inability of the lazaroid compound 2-MAC to sustain cytoprotection in the later stages of cell injury might provide at least a partial explanation for the inefficiency of lazaroids to limit tissue injury in clinical and certain in vivo settings.
authors.affiliation: Department of Medicine, University of Mississippi Medical Center, Jackson, MS 39216-4505, USA.
authors.forename: H
authors.initials: H
authors.lastname: Huang
authors.forename: P B
authors.initials: PB
authors.lastname: Patel
authors.forename: A K
authors.initials: AK
authors.lastname: Salahudeen
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D000975:Antioxidants / Q000494:pharmacology*; D002460:Cell Line; D002614:Chelating Agents / Q000494:pharmacology / Q000627:therapeutic use; D002839:Chromans / Q000494:pharmacology / Q000627:therapeutic use; D002986:Clinical Trials as Topic / Q000379:methods; D003676:Deferoxamine / Q000494:pharmacology / Q000627:therapeutic use; D006861:Hydrogen Peroxide / Q000037:antagonists & inhibitors / Q000494:pharmacology; D007668:Kidney / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism / Q000473:pathology*; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D015227:Lipid Peroxidation / Q000187:drug effects; D016877:Oxidants / Q000037:antagonists & inhibitors* / Q000633:toxicity*; D010879:Piperazines / Q000494:pharmacology / Q000627:therapeutic use; D013256:Steroids / Q000494:pharmacology / Q000627:therapeutic use; D013552:Swine
chemical_list: D000975:Antioxidants; D002614:Chelating Agents; D002839:Chromans; D016877:Oxidants; D010879:Piperazines; D013256:Steroids; C066382:U 78517F; D000255:Adenosine Triphosphate; D006861:Hydrogen Peroxide; D007770:L-Lactate Dehydrogenase; D003676:Deferoxamine