title: Susceptibility of human head and neck cancer cells to combined inhibition of glutathione and thioredoxin metabolism.
abstract: Increased glutathione (GSH) and thioredoxin (Trx) metabolism are mechanisms that are widely implicated in resistance of cancer cells to chemotherapy. The current study determined if simultaneous inhibition of GSH and Trx metabolism enhanced cell killing of human head and neck squamous cell carcinoma (HNSCC) cells by a mechanism involving oxidative stress. Inhibition of GSH and Trx metabolism with buthionine sulfoximine (BSO) and auranofin (AUR), respectively, induced significant decreases in clonogenic survival compared to either drug alone in FaDu, Cal-27 and SCC-25 HNSCC cells in vitro and in vivo in Cal-27 xenografts. BSO+AUR significantly increased glutathione and thioredoxin oxidation and suppressed peroxiredoxin activity in vitro. Pre-treatment with N-acetylcysteine completely reversed BSO+AUR-induced cell killing in FaDu and Cal-27 cells, while catalase and selenium supplementation only inhibited BSO+AUR-induced cell killing in FaDu cells. BSO+AUR decreased caspase 3/7 activity in HNSCC cells and significantly reduced the viability of both Bax/Bak double knockout (DKO) and DKO-Bax reconstituted hematopoietic cells suggesting that necrosis was involved. BSO+AUR also significantly sensitized FaDu, Cal-27, SCC-25 and SQ20B cells to cell killing induced by the EGFR inhibitor Erlotinib in vitro. These results support the conclusion that simultaneous inhibition of GSH and Trx metabolism pathways induces oxidative stress and clonogenic killing in HNSCCs and this strategy may be useful in sensitizing HNSCCs to EGFR inhibitors.
authors.affiliation: Department of Pathology, The University of Iowa, Iowa City, Iowa, USA.
authors.forename: Arya
authors.initials: A
authors.lastname: Sobhakumari
authors.forename: Laurie
authors.initials: L
authors.lastname: Love-Homan
authors.forename: Elise V M
authors.initials: EV
authors.lastname: Fletcher
authors.forename: Sean M
authors.initials: SM
authors.lastname: Martin
authors.forename: Arlene D
authors.initials: AD
authors.lastname: Parsons
authors.forename: Douglas R
authors.initials: DR
authors.lastname: Spitz
authors.forename: C Michael
authors.initials: CM
authors.lastname: Knudson
authors.forename: Andrean L
authors.initials: AL
authors.lastname: Simons
mesh_terms: D000818:Animals; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000494:pharmacology* / Q000627:therapeutic use; D001310:Auranofin / Q000008:administration & dosage; D019328:Buthionine Sulfoximine / Q000008:administration & dosage; D002294:Carcinoma, Squamous Cell / Q000188:drug therapy*; D002374:Catalase / Q000378:metabolism; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D004357:Drug Synergism; D000069347:Erlotinib Hydrochloride; D005260:Female; D055785:Gene Knockdown Techniques; D005978:Glutathione / Q000096:biosynthesis*; D005979:Glutathione Peroxidase / Q000378:metabolism; D005980:Glutathione Reductase / Q000378:metabolism; D006258:Head and Neck Neoplasms / Q000188:drug therapy*; D006801:Humans; D051379:Mice; D008819:Mice, Nude; D009336:Necrosis; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D054464:Peroxiredoxins / Q000378:metabolism; D011799:Quinazolines / Q000008:administration & dosage; D034741:RNA, Small Interfering / Q000235:genetics; D013880:Thioredoxin-Disulfide Reductase / Q000235:genetics / Q000378:metabolism; D013879:Thioredoxins / Q000096:biosynthesis*; D023041:Xenograft Model Antitumor Assays
chemical_list: D011799:Quinazolines; D034741:RNA, Small Interfering; D001310:Auranofin; D019328:Buthionine Sulfoximine; D013879:Thioredoxins; D000069347:Erlotinib Hydrochloride; D054464:Peroxiredoxins; D002374:Catalase; D005979:Glutathione Peroxidase; D005980:Glutathione Reductase; D013880:Thioredoxin-Disulfide Reductase; D005978:Glutathione