title: NF-kappaB is involved in SHetA2 circumvention of TNF-alpha resistance, but not induction of intrinsic apoptosis.
abstract: Treatment of cancer with tumor necrosis factor-alpha (TNF-alpha) is hindered by resistance and toxicity. The flexible heteroarotinoid, SHetA2, sensitizes resistant ovarian cancer cells to TNF-alpha-induced extrinsic apoptosis, and also induces intrinsic apoptosis as a single agent. This study tested the hypothesis that nuclear factor-kappaB (NF-kappaB) is involved in SHetA2-regulated intrinsic and extrinsic apoptosis. SHetA2 inhibited basal and TNF-alpha-induced or hydrogen peroxide-induced NF-kappaB activity through counter-regulation of upstream kinase (IkappaB kinase) activity, inhibitor protein (IkappaB-alpha) phosphorylation, and p-65 NF-kappaB subunit nuclear translocation, but independently of reactive oxygen species generation. Ectopic over-expression of p-65, or treatment with TNF-alpha receptor 1 (TNFR1) small interfering RNA or a caspase-8 inhibitor, each attenuated synergistic apoptosis by SHetA2 and TNF-alpha, but did not affect intrinsic apoptosis caused by SHetA2. In conclusion, NF-kappaB repression is involved in SHetA2 circumvention of resistance to TNF-alpha-induced extrinsic apoptosis, but not in SHetA2 induction of intrinsic apoptosis.
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104, USA.
authors.forename: Shylet
authors.initials: S
authors.lastname: Chengedza
authors.forename: Doris Mangiaracina
authors.initials: DM
authors.lastname: Benbrook
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology; D017209:Apoptosis; D045744:Cell Line, Tumor; D002839:Chromans / Q000627:therapeutic use*; D019008:Drug Resistance, Neoplasm; D005260:Female; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D051550:I-kappa B Kinase / Q000037:antagonists & inhibitors; D016328:NF-kappa B / Q000378:metabolism*; D010051:Ovarian Neoplasms / Q000188:drug therapy* / Q000378:metabolism; D013871:Thiones / Q000627:therapeutic use*; D014409:Tumor Necrosis Factor-alpha / Q000627:therapeutic use*
chemical_list: C476105:(((4-nitrophenyl)amino)(2,2,4,4-tetramethyl thiochroman-6-yl)amino) methane-1-thione; D000970:Antineoplastic Agents; D002839:Chromans; D016328:NF-kappa B; D013871:Thiones; D014409:Tumor Necrosis Factor-alpha; D006861:Hydrogen Peroxide; D051550:I-kappa B Kinase