title: Nitric oxide sensitizes tumor cells to TRAIL-induced apoptosis via inhibition of the DR5 transcription repressor Yin Yang 1.
abstract: Treatment of TRAIL-resistant tumor cells with the nitric oxide donor DETANONOate sensitizes the tumor cells to TRAIL-induced apoptosis concomitantly with DR5 upregulation. The mechanism of sensitization was examined based on the hypothesis that DETANONOate inhibits a transcription repressor Yin Yang 1 (YY1) that negatively regulates DR5 transcription. Treatment of the prostate carcinoma cell lines with DETANONOate inhibited both NF-kappaB and YY1 DNA-binding activities concomitantly with upregulation of DR5 expression. The direct role of YY1 in the regulation of TRAIL resistance was demonstrated in cells treated with YY1 siRNA resulting in TRAIL-induced apoptosis. The role of YY1 in the transcriptional regulation of DR5 was examined in cells treated with a DR5 luciferase reporter system (pDR5) and two constructs, namely, the pDR5/-605 construct with a deletion of the putative YY1 DNA-binding region (-1224 to -605) and a construct pDR5-YY1 with a mutation of the YY1 DNA-binding site. A significant (3-fold) augmentation of luciferase activity over baseline transfection with pDR5 was observed in cells transfected with the modified constructs. ChIP analysis corroborated the YY1 binding to the DR5 promoter. In vivo, tissues from nude mice bearing the PC-3 xenograft and treated with DETANONOate showed inhibition of YY1 and upregulation of DR5. The present findings demonstrate that YY1 negatively regulates DR5 transcription and expression and these correlated with resistance to TRAIL-induced apoptosis. DETANONOate inhibits both NF-kappaB and YY1 and in combination with TRAIL reverses tumor cell resistance to TRAIL apoptosis.
authors.affiliation: Department of Microbiology, Immunology and Molecular Genetics, Jonsson Comprehensive Cancer Center, David Geffen School of Medicine, University of California, 10833 Le Conte Avenue, A2-060, Los Angeles, CA 90095-73622, USA.
authors.forename: Sara
authors.initials: S
authors.lastname: Huerta-Yepez
authors.forename: Mario
authors.initials: M
authors.lastname: Vega
authors.forename: Saul E
authors.initials: SE
authors.lastname: Escoto-Chavez
authors.forename: Benjamin
authors.initials: B
authors.lastname: Murdock
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Sakai
authors.forename: Stavroula
authors.initials: S
authors.lastname: Baritaki
authors.forename: Benjamin
authors.initials: B
authors.lastname: Bonavida
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D045744:Cell Line, Tumor; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D051379:Mice; D008819:Mice, Nude; D016328:NF-kappa B / Q000378:metabolism; D009368:Neoplasm Transplantation; D009569:Nitric Oxide / Q000378:metabolism*; D020030:Nitric Oxide Donors / Q000494:pharmacology*; D009603:Nitroso Compounds / Q000494:pharmacology*; D020411:Oligonucleotide Array Sequence Analysis; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand / Q000235:genetics / Q000378:metabolism*; D053221:TNF-Related Apoptosis-Inducing Ligand / Q000502:physiology*; D014183:Transplantation, Heterologous; D050986:YY1 Transcription Factor / Q000235:genetics / Q000378:metabolism*
chemical_list: D016328:NF-kappa B; D020030:Nitric Oxide Donors; D009603:Nitroso Compounds; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand; D053221:TNF-Related Apoptosis-Inducing Ligand; D050986:YY1 Transcription Factor; C094210:2,2'-(hydroxynitrosohydrazono)bis-ethanamine; D009569:Nitric Oxide