Tumor necrosis factor-related apoptosis inducing ligand (TRAIL) up-regulates death receptor 5 (DR5) mediated by NFkappaB activation in epithelial derived cell lines.
Tumor necrosis factor-related apoptosis inducing ligand (TRAIL/APO-2L) activates nuclear factor kappaB (NFkappaB). This activation is regulated by the recruitment of an adaptor protein Fas associating death domain (FADD) to TRAIL death receptors, death receptor 4 (DR4, TRAIL-R1) and death receptor 5 (DR5 TRAIL-R2). This leads to recruitment of caspase 8 and receptor interacting protein (RIP) to the receptor complex. Upon recruitment of caspase 8 and RIP, NFkappaB inducing kinase (NIK) becomes activated causing NFkappaB activation. The role of TRAIL induced NFkappaB activation in epithelial cells is unknown. Herein we demonstrate that TRAIL increases expression of DR5 in human embryonic kidney (HEK) 293, MCF-7 and MDA MB 231 epithelial cell lines while DR4 expression remains unchanged. Blockage of NFkappaB activation either by expression of dominant negative IkappaB or treatment with proteasome inhibitor lactacystin eliminates TRAIL induced DR5 expression. Expression of FADD dominant negative in HEK 293 cells that prevents the recruitment of caspase 8 and RIP to TRAIL death receptors also eliminates this increase. By over expression of the p65 subunit of NFkappaB that increases NFkappaB transcriptional activity, DR5 expression was increased compared to vector alone expressing cells. By blocking TRAIL induced NFkappaB activation, the sensitivity of cells to undergo TRAIL induced apoptosis was significantly decreased. Conversely, the amount of TRAIL induced apoptosis was increased in HEK 293 cells over expressing p65 subunit of NFkappaB. Finally blockage of NFkappaB activation eliminates the synergistic apoptotic response of TRAIL and etoposide. Thus, TRAIL mediated NFkappaB activation increases DR5 expression thereby amplifying the apoptotic response of TRAIL in epithelial derived cells.
Manitoba Institute of Cell Biology, University of Manitoba, 675 McDermot Ave, Winnipeg, MB R3E 0V9.
S
S
Shetty
J Brown
JB
Gladden
E S
ES
Henson
X
X
Hu
J
J
Villanueva
N
N
Haney
S B
SB
Gibson
D048868:Adaptor Proteins, Signal Transducing; D051017:Apoptosis Regulatory Proteins; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions / Q000502:physiology; D004847:Epithelial Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D005047:Etoposide / Q000494:pharmacology; D053200:Fas-Associated Death Domain Protein; D005822:Genetic Vectors; D006801:Humans; D020672:I-kappa B Proteins / Q000235:genetics / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000378:metabolism* / Q000494:pharmacology; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism*; D019384:Nucleic Acid Synthesis Inhibitors / Q000494:pharmacology; D012333:RNA, Messenger / Q000187:drug effects / Q000378:metabolism; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand; D018124:Receptors, Tumor Necrosis Factor / Q000235:genetics / Q000378:metabolism*; D053221:TNF-Related Apoptosis-Inducing Ligand; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism* / Q000494:pharmacology; D015854:Up-Regulation / Q000187:drug effects / Q000502:physiology*
D048868:Adaptor Proteins, Signal Transducing; D051017:Apoptosis Regulatory Proteins; D002352:Carrier Proteins; C505533:FADD protein, human; D053200:Fas-Associated Death Domain Protein; D020672:I-kappa B Proteins; D008562:Membrane Glycoproteins; D016328:NF-kappa B; D019384:Nucleic Acid Synthesis Inhibitors; D012333:RNA, Messenger; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand; D018124:Receptors, Tumor Necrosis Factor; D053221:TNF-Related Apoptosis-Inducing Ligand; C505639:TNFRSF10B protein, human; C505653:TNFSF10 protein, human; D014409:Tumor Necrosis Factor-alpha; D005047:Etoposide