title: Combined inhibition of glycolysis, the pentose cycle, and thioredoxin metabolism selectively increases cytotoxicity and oxidative stress in human breast and prostate cancer.
abstract: Inhibition of glycolysis using 2-deoxy-d-glucose (2DG, 20mM, 24-48h) combined with inhibition of the pentose cycle using dehydroepiandrosterone (DHEA, 300µM, 24-48h) increased clonogenic cell killing in both human prostate (PC-3 and DU145) and human breast (MDA-MB231) cancer cells via a mechanism involving thiol-mediated oxidative stress. Surprisingly, when 2DG+DHEA treatment was combined with an inhibitor of glutathione (GSH) synthesis (l-buthionine sulfoximine; BSO, 1mM) that depleted GSH>90% of control, no further increase in cell killing was observed during 48h exposures. In contrast, when an inhibitor of thioredoxin reductase (TrxR) activity (Auranofin; Au, 1µM), was combined with 2DG+DHEA or DHEA-alone for 24h, clonogenic cell killing was significantly increased in all three human cancer cell lines. Furthermore, enhanced clonogenic cell killing seen with the combination of DHEA+Au was nearly completely inhibited using the thiol antioxidant, N-acetylcysteine (NAC, 20mM). Redox Western blot analysis of PC-3 cells also supported the conclusion that thioredoxin-1 (Trx-1) oxidation was enhanced by treatment DHEA+Au and inhibited by NAC. Importantly, normal human mammary epithelial cells (HMEC) were not as sensitive to 2DG, DHEA, and Au combinations as their cancer cell counterparts (MDA-MB-231). Overall, these results support the hypothesis that inhibition of glycolysis and pentose cycle activity, combined with inhibition of Trx metabolism, may provide a promising strategy for selectively sensitizing human cancer cells to oxidative stress-induced cell killing.
authors.affiliation: Department of Radiation Oncology, Free Radical and Radiation Biology Program, Holden Comprehensive Cancer Center, University of Iowa, Iowa City, IA 52242, USA.
authors.forename: Ling
authors.initials: L
authors.lastname: Li
authors.affiliation: Department of Radiation Oncology, Free Radical and Radiation Biology Program, Holden Comprehensive Cancer Center, University of Iowa, Iowa City, IA 52242, USA.
authors.forename: Melissa A
authors.initials: MA
authors.lastname: Fath
authors.affiliation: Duke Cancer Institute, Duke University, Durham, NC 27705, USA.
authors.forename: Peter M
authors.initials: PM
authors.lastname: Scarbrough
authors.affiliation: Division of Gastroenterology, Hepatology and Nutrition, Department of Medicine, University of Louisville, Louisville, KY 40292, USA.
authors.forename: Walter H
authors.initials: WH
authors.lastname: Watson
authors.affiliation: Department of Radiation Oncology, Free Radical and Radiation Biology Program, Holden Comprehensive Cancer Center, University of Iowa, Iowa City, IA 52242, USA. Electronic address: douglas-spitz@uiowa.edu.
authors.forename: Douglas R
authors.initials: DR
authors.lastname: Spitz
mesh_terms: D000975:Antioxidants / Q000008:administration & dosage; D001943:Breast Neoplasms / Q000188:drug therapy / Q000378:metabolism* / Q000473:pathology; D045744:Cell Line, Tumor; D003687:Dehydroepiandrosterone / Q000008:administration & dosage; D003847:Deoxyglucose / Q000008:administration & dosage; D004357:Drug Synergism; D005260:Female; D006019:Glycolysis / Q000187:drug effects; D006801:Humans; D008297:Male; D018384:Oxidative Stress / Q000187:drug effects; D010427:Pentose Phosphate Pathway / Q000187:drug effects; D011471:Prostatic Neoplasms / Q000188:drug therapy / Q000378:metabolism* / Q000473:pathology; D013879:Thioredoxins / Q000037:antagonists & inhibitors / Q000378:metabolism*
chemical_list: D000975:Antioxidants; C491203:TXN protein, human; D003687:Dehydroepiandrosterone; D013879:Thioredoxins; D003847:Deoxyglucose
keywords: 2-Deoxy-d-glucose; Auranofin; Buthionine sulfoximine; Cancer; Dehydroepiandrosterone; Glutathione; Oxidative stress; Pentose phosphate pathway; Thioredoxin