title: Death receptor-4 (DR4) expression is regulated by transcription factor NF-kappaB in response to etoposide treatment.
abstract: Tumour necrosis factor related apoptosis inducing ligand (TRAIL) binds to death receptor 4 (DR4) activating the apoptotic signalling pathway. DNA damaging agents (genotoxins) such as etoposide increase DR4 expression and when combined with TRAIL induce a synergistic apoptotic response. The mechanism for up-regulation of DR4 expression following genotoxin treatment is not well understood. Herein, we determined that transcription factor NF-kappaB plays a role in genotoxin induced DR4 expression. Increased expression of DR4 following etoposide treatment is blocked by inhibition of the NF-kappaB pathway. Moreover, expression of the p65 subunit of NF-kappaB is sufficient to increase DR4 protein levels. Indeed, knockdown of p65 by RNA interference blocked etoposide up-regulation of DR4. We further identified a functional NF-kappaB binding site located in the DR4 promoter. Mutation of this site abrogates the induction of luciferase activity after p65 over-expression. Furthermore, electromobility shift assays and chromatin immunoprecipitaton suggest that NF-kappaB binds to this site upon etoposide treatment. MEK kinase 1 (MEKK1) is a serine threonine kinase that is activated following etoposide treatment and activates NF-kappaB. Expression of the kinase inactive MEKK1 (MEKK1-KM) abrogates the up-regulation of DR4 after etoposide treatment. Taken together, NF-kappaB plays a role in up-regulation of DR4 following etoposide treatment.
authors.affiliation: Manitoba Institute of Cell Biology, University of Manitoba, 675 McDermot Ave, Winnipeg, MB, Canada R3E 0V9.
authors.forename: Francisco José
authors.initials: FJ
authors.lastname: Mendoza
authors.forename: Ganchimeg
authors.initials: G
authors.lastname: Ishdorj
authors.forename: Xiaojie
authors.initials: X
authors.lastname: Hu
authors.forename: Spencer B
authors.initials: SB
authors.lastname: Gibson
mesh_terms: D000911:Antibodies, Monoclonal / Q000494:pharmacology; D061067:Antibodies, Monoclonal, Humanized; D017209:Apoptosis / Q000187:drug effects; D001665:Binding Sites; D002460:Cell Line; D053938:DNA Fragmentation / Q000187:drug effects; D005047:Etoposide / Q000494:pharmacology*; D019073:HT29 Cells; D006801:Humans; D048728:MAP Kinase Kinase Kinase 1 / Q000502:physiology; D016328:NF-kappa B / Q000502:physiology*; D009570:Nitriles / Q000494:pharmacology; D011401:Promoter Regions, Genetic / Q000187:drug effects; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand; D018124:Receptors, Tumor Necrosis Factor / Q000096:biosynthesis*; D013450:Sulfones / Q000494:pharmacology; D053221:TNF-Related Apoptosis-Inducing Ligand / Q000494:pharmacology; D051996:Transcription Factor RelA / Q000502:physiology; D015854:Up-Regulation
chemical_list: C434003:3-(4-methylphenylsulfonyl)-2-propenenitrile; D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D016328:NF-kappa B; D009570:Nitriles; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand; D018124:Receptors, Tumor Necrosis Factor; D013450:Sulfones; D053221:TNF-Related Apoptosis-Inducing Ligand; C105190:TNFRSF10A protein, human; C505653:TNFSF10 protein, human; D051996:Transcription Factor RelA; D005047:Etoposide; D048728:MAP Kinase Kinase Kinase 1; C507357:mapatumumab