The role of hypoxia in the resistance of cancer cells to DNA damaging agents has been clearly demonstrated in in vitro and in vivo. Several clinical studies have also demonstrated poor therapeutic outcome for hypoxic tumors. DNA repair, repair protein Kf, and intracellular GSH detoxification play a major role in cellular response to DNA damaging topoisomerase II inhibitors and gamma radiation. Although the functions of these factors can be inhibited by oxidation of functional thiols, cells resist thiol redox changes by producing NADPH through oxidative pentose phosphate cycle (OPPC). For example hydroxyethyldisulfide (HEDS), a unique non-toxic thiol oxidant, is not effective in modifying the cellular thiol redox in normal CHO cells with OPPC. Our preliminary studies indicated, for the first time, that CHO mutants impaired with OPPC activity are the ideal candidates for HEDS-mediated sensitization to DNA damaging agents. This unique property of OPPC, which eliminates HEDS-mediated thiol redox modification and DNA damage sensitization, will be exploited to sensitize hypoxic cancer cells deprived of glucose, a substrate for OPPC, without affecting glucose proficient normal cells. Glucose deprivation is common in hypoxic cells of several solid tumors because of poor vascularization and higher metabolic activity. We hypothesize that glucose/OPPC depleted hypoxic cancer cells are susceptible to HEDS-mediated redox [Protein thiol (PSH) & glutathione (GSH)] modification and sensitization to """"""""and tumor and DNA damaging"""""""" Topo II inhibitors and gamma radiation through multiple mechanisms that include inhibition of DNA repair, DNA repair protein function, GSH detoxification, and anti-apoptotic factors. We will test our hypothesis in hypoxic human cancer cells using biochemical and molecular approaches. First, we will determine the application of thiol redox modification in the sensitization of glucose deprived hypoxic cancer cells to topo II inhibitors and gamma radiation. Additional studies will also be conducted to test the efficacy of HEDS in low glucose hypoxic tumor in in vivo. Second, using siRNA and antibody technologies, we will determine whether specific inhibitors of OPPC can also induce HEDS-mediated redox modification, and subsequent sensitization of hypoxic cancer cells to DNA damaging agents. Finally, we will determine the mechanisms of redox modification- mediated hypoxic sensitization by determining its effect on DNA double strand breaks, DNA repair protein Kf, GSH detoxification and pro-apoptotic factors.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
5R01CA109604-05
Application #
7356449
Study Section
Drug Discovery and Molecular Pharmacology Study Section (DMP)
Program Officer
Bernhard, Eric J
Project Start
2005-04-01
Project End
2011-02-28
Budget Start
2008-03-01
Budget End
2011-02-28
Support Year
5
Fiscal Year
2008
Total Cost
$245,908
Indirect Cost
Name
Lankenau Institute for Medical Research
Department
Type
DUNS #
125797084
City
Wynnewood
State
PA
Country
United States
Zip Code
19096
Li, Jie; Zhang, Donglan; Jefferson, Pearl A et al. (2014) A bioactive probe for glutathione-dependent antioxidant capacity in breast cancer patients: implications in measuring biological effects of arsenic compounds. J Pharmacol Toxicol Methods 69:39-48
Li, Jie; Ward, Kathleen M; Zhang, Donglan et al. (2013) A bioactive probe of the oxidative pentose phosphate cycle: novel strategy to reverse radioresistance in glucose deprived human colon cancer cells. Toxicol In Vitro 27:367-77
Li, Jie; Zhang, Donglan; Ward, Kathleen M et al. (2012) Hydroxyethyl disulfide as an efficient metabolic assay for cell viability in vitro. Toxicol In Vitro 26:603-12
Li, Jie; Ayene, Roashan; Ward, Kathleen M et al. (2009) Glucose deprivation increases nuclear DNA repair protein Ku and resistance to radiation induced oxidative stress in human cancer cells. Cell Biochem Funct 27:93-101
Ayene, Iraimoudi S; Biaglow, John E; Kachur, Alexander V et al. (2008) Mutation in G6PD gene leads to loss of cellular control of protein glutathionylation: mechanism and implication. J Cell Biochem 103:123-35
Tuttle, Stephen W; Maity, Amit; Oprysko, Patricia R et al. (2007) Detection of reactive oxygen species via endogenous oxidative pentose phosphate cycle activity in response to oxygen concentration: implications for the mechanism of HIF-1alpha stabilization under moderate hypoxia. J Biol Chem 282:36790-6
Ayene, Iraimoudi S; Koch, Cameron J; Krisch, Robert E (2007) DNA strand breakage by bivalent metal ions and ionizing radiation. Int J Radiat Biol 83:195-210
Biaglow, John E; Ayene, Iraimoudi S; Tuttle, Stephen W et al. (2006) Role of vicinal protein thiols in radiation and cytotoxic responses. Radiat Res 165:307-17