Unsaturated membrane lipids in cells confronted with physical or chemical oxidative insults may undergo peroxidative damage, often with deleterious consequences. Lipid hydroperoxides (LOOHs), including phospholipid (PL)- and cholesterol (Ch)-derived species, are important non-radical intermediates in such reactions. Once formed, LOOHs can have a variety of fates which impact on the viability of a targeted cell. A nascent LOOH may undergo iron-catalyzed one-electron reduction to free radical species, which trigger damaging (toxicity-enhancing) chain peroxidation reactions. Alternatively, selenoperoxidase (GPX4)-catalyzed detoxification of LOOHs may occur, i.e. two-electron reduction to relatively innocuous alcohols. While studying these processes, we have identified a new pathway, which expands the LOOH dynamic, viz. intermembrane translocation. The proposed research will delve more deeply into this phenomenon with two hypotheses in mind: (i) LOOHs move between membranes more rapidly than parent lipids, both intra- and intercellularly, and this is enhanced by transfer proteins. (ii) Availability of redox iron or GPX4 at acceptor sites will determine whether translocation expands or attenuates LOOH cytotoxicity. The studies will utilize GPX4-null COH-BR1 breast tumor cells, transfectants thereof overexpressing either mitochondrial or non-mitochondrial GPX4, and transfectants overexpressing non-specific lipid transfer protein (SCP-2). High sensitivity/specificity techniques for detecting LOOHs and other oxidation products will be employed, viz. HPLC-EC(Hg) and HPTLC-PI, both of which were developed in this laboratory. The hypotheses will be tested by studying (i) spontaneous and SCP-2-facilitated LOOH transfer between plasma membranes (PM) and mitochondria (Mito) isolated from tumor cells; (ii) one-electron vs. two-electron reactivity of transfer-acquired LOOHs in PM and Mito; (iii) effects of SCP-2 overexpression on subcellular LOOH trafficking and cytotoxicity; and (iv) possible cooperative effects of SCP-2 and GPX4 co-overexpression on LOOH detoxification. By exploring this new dimension in LOOH bioreactivity, these studies will provide valuable new insights into the cytopathological effects of these species.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
2R01CA072630-05
Application #
6689148
Study Section
Chemical Pathology Study Section (CPA)
Program Officer
Okano, Paul
Project Start
1998-04-16
Project End
2008-07-31
Budget Start
2003-08-08
Budget End
2004-07-31
Support Year
5
Fiscal Year
2003
Total Cost
$300,375
Indirect Cost
Name
Medical College of Wisconsin
Department
Biochemistry
Type
Schools of Medicine
DUNS #
937639060
City
Milwaukee
State
WI
Country
United States
Zip Code
53226
Girotti, Albert W; Korytowski, Witold (2018) Cholesterol Peroxidation as a Special Type of Lipid Oxidation in Photodynamic Systems. Photochem Photobiol :
Girotti, Albert W; Korytowski, Witold (2017) Cholesterol Hydroperoxide Generation, Translocation, and Reductive Turnover in Biological Systems. Cell Biochem Biophys 75:413-419
Girotti, Albert W; Korytowski, Witold (2016) Cholesterol as a natural probe for free radical-mediated lipid peroxidation in biological membranes and lipoproteins. J Chromatogr B Analyt Technol Biomed Life Sci 1019:202-9
Korytowski, Witold; Wawak, Katarzyna; Pabisz, Pawel et al. (2015) Impairment of Macrophage Cholesterol Efflux by Cholesterol Hydroperoxide Trafficking: Implications for Atherogenesis Under Oxidative Stress. Arterioscler Thromb Vasc Biol 35:2104-13
Grim, Jeffrey M; Hyndman, Kelly A; Kriska, Tamas et al. (2011) Relationship between oxidizable fatty acid content and level of antioxidant glutathione peroxidases in marine fish. J Exp Biol 214:3751-9
Korytowski, Witold; Basova, Liana V; Pilat, Anna et al. (2011) Permeabilization of the mitochondrial outer membrane by Bax/truncated Bid (tBid) proteins as sensitized by cardiolipin hydroperoxide translocation: mechanistic implications for the intrinsic pathway of oxidative apoptosis. J Biol Chem 286:26334-43
Korytowski, Witold; Schmitt, Jared C; Girotti, Albert W (2010) Surprising inability of singlet oxygen-generated 6-hydroperoxycholesterol to induce damaging free radical lipid peroxidation in cell membranes. Photochem Photobiol 86:747-51
Korytowski, Witold; Rodriguez-Agudo, Daniel; Pilat, Anna et al. (2010) StarD4-mediated translocation of 7-hydroperoxycholesterol to isolated mitochondria: deleterious effects and implications for steroidogenesis under oxidative stress conditions. Biochem Biophys Res Commun 392:58-62
Kriska, Tamas; Pilat, Anna; Schmitt, Jared C et al. (2010) Sterol carrier protein-2 (SCP-2) involvement in cholesterol hydroperoxide cytotoxicity as revealed by SCP-2 inhibitor effects. J Lipid Res 51:3174-84
Kriska, Tamas; Levchenko, Vladislav V; Chu, Fong-Fong et al. (2008) Novel enrichment of tumor cell transfectants expressing high levels of type 4 glutathione peroxidase using 7alpha-hydroperoxycholesterol as a selection agent. Free Radic Biol Med 45:700-7

Showing the most recent 10 out of 35 publications