title: Oxyphenisatin acetate (NSC 59687) triggers a cell starvation response leading to autophagy, mitochondrial dysfunction, and autocrine TNFα-mediated apoptosis.
abstract: Oxyphenisatin (3,3-bis(4-hydroxyphenyl)-1H-indol-2-one) and several structurally related molecules have been shown to have in vitro and in vivo antiproliferative activity. This study aims to confirm and extend mechanistic studies by focusing on oxyphenisatin acetate (OXY, NSC 59687), the pro-drug of oxyphenisatin. Results confirm that OXY inhibits the growth of the breast cancer cell lines MCF7, T47D, HS578T, and MDA-MB-468. This effect is associated with selective inhibition of translation accompanied by rapid phosphorylation of the nutrient sensing eukaryotic translation initiation factor 2α (eIF2α) kinases, GCN2 and PERK. This effect was paralleled by activation of AMP-activated protein kinase (AMPK) combined with reduced phosphorylation of the mammalian target of rapamycin (mTOR) substrates p70S6K and 4E-BP1. Microarray analysis highlighted activation of pathways involved in apoptosis induction, autophagy, RNA/protein metabolism, starvation responses, and solute transport. Pathway inhibitor combination studies suggested a role for AMPK/mTOR signaling, de novo transcription and translation, reactive oxygen species (ROS)/glutathione metabolism, calcium homeostasis and plasma membrane Na(+) /K(+) /Ca(2+) transport in activity. Further examination confirmed that OXY treatment was associated with autophagy, mitochondrial dysfunction, and ROS generation. Additionally, treatment was associated with activation of both intrinsic and extrinsic apoptotic pathways. In the estrogen receptor (ER) positive MCF7 and T47D cells, OXY induced TNFα expression and TNFR1 degradation, indicating autocrine receptor-mediated apoptosis in these lines. Lastly, in an MCF7 xenograft model, OXY delivered intraperitoneally inhibited tumor growth, accompanied by phosphorylation of eIF2α and degradation of TNFR1. These data suggest that OXY induces a multifaceted cell starvation response, which ultimately induces programmed cell death.
authors.affiliation: Drug Mechanism Group, Biological Testing Branch, Developmental Therapeutics Program, SAIC-Frederick Inc., Frederick National Laboratory for Cancer Research, Frederick, Maryland, 21702.
authors.forename: Bethanie L
authors.initials: BL
authors.lastname: Morrison
authors.forename: Michael E
authors.initials: ME
authors.lastname: Mullendore
authors.forename: Luke H
authors.initials: LH
authors.lastname: Stockwin
authors.forename: Suzanne
authors.initials: S
authors.lastname: Borgel
authors.forename: Melinda G
authors.initials: MG
authors.lastname: Hollingshead
authors.forename: Dianne L
authors.initials: DL
authors.lastname: Newton
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D019898:Autocrine Communication / Q000187:drug effects; D001343:Autophagy / Q000187:drug effects*; D001943:Breast Neoplasms / Q000378:metabolism / Q000473:pathology*; D049109:Cell Proliferation / Q000187:drug effects; D004353:Drug Evaluation, Preclinical / Q000379:methods; D005260:Female; D006801:Humans; D008325:Mammary Neoplasms, Experimental / Q000378:metabolism / Q000473:pathology; D051379:Mice; D008819:Mice, Nude; D008928:Mitochondria / Q000187:drug effects* / Q000502:physiology; D009363:Neoplasm Proteins / Q000378:metabolism; D010114:Oxyphenisatin Acetate / Q000494:pharmacology*; D010766:Phosphorylation / Q000187:drug effects; D014176:Protein Biosynthesis / Q000187:drug effects; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D047888:Receptors, Tumor Necrosis Factor, Type I / Q000378:metabolism; D046888:Tissue Array Analysis / Q000379:methods; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000502:physiology; D023041:Xenograft Model Antitumor Assays / Q000379:methods
chemical_list: D009363:Neoplasm Proteins; D047888:Receptors, Tumor Necrosis Factor, Type I; C506236:Tnfrsf1a protein, mouse; D014409:Tumor Necrosis Factor-alpha; C070634:Eif2ak4 protein, mouse; D017346:Protein Serine-Threonine Kinases; C531557:eIF2alpha kinase, mouse; D010114:Oxyphenisatin Acetate
keywords: Autophagy; TNFα; breast cancer; oxyphenisatin; protein synthesis