Resistance of human ovarian cancer cells to tumor necrosis factor alpha is a consequence of nuclear factor kappaB-mediated induction of Fas-associated death domain-like interleukin-1beta-converting enzyme-like inhibitory protein.
The purpose of the present studies was to examine the role and regulation of Fas-associated death domain-like IL-1- converting enzyme-like inhibitory protein [FLIP; long (FLIP(L)) and short (FLIP(S)) forms] in human ovarian epithelial cancer cells by TNFalpha and their significance in the resistance of the cells to the proapoptotic action of the cytokine. OV2008, A2780-s, and OVCAR-3 cells were cultured in serum-free media with or without cycloheximide (CHX, 10 micro g/ml) +/- TNFalpha (5, 10, 20 ng/ml) or transfected with a mammalian expression vector containing either a dominant negative inhibitor kappaB (IkappaB), FLIP(S) sense or antisense cDNA and cultured with or without TNFalpha. In the presence of CHX, TNFalpha increased caspase-8 and -3 cleavage and apoptosis. It also induced IkappaB phosphorylation, nuclear factor kappaB activation, and the expression of FLIP(S) but not of FLIP(L). Overexpression of dominant negative IkappaB attenuated TNFalpha-induced FLIP(S) expression and enhanced TNFalpha-induced apoptosis. Apoptosis induced by TNFalpha and CHX was facilitated by FLIP(S) antisense expression but attenuated by sense transfection. This study demonstrates that TNFalpha up-regulates FLIP(S) expression, and this effect is mediated by the activation of nuclear factor kappaB. The induction of FLIP(S) expression by TNFalpha might contribute to the resistance of ovarian epithelial cancer cells to the proapoptotic action of the cytokine.
Xiao
Chao Wu
CW
Department of Obstetrics and Gynecology and Cellular and Molecular Medicine, University of Ottawa, Ottawa Health Research Institute, The Ottawa Hospital, Ottawa, Ontario, Canada K1Y 4E9.
Yan
Xiaojuan
X
Li
Yulian
Y
Reddy
Shrikanth A G
SA
Tsang
Benjamin K
BK
D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology; D053446:CASP8 and FADD-Like Apoptosis Regulating Protein; D002352:Carrier Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D020170:Caspase 1 / Q000737:chemistry; D053148:Caspase 3; D053181:Caspase 8; D053453:Caspase 9; D020169:Caspases / Q000378:metabolism; D003513:Cycloheximide / Q000494:pharmacology; D019008:Drug Resistance, Neoplasm; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D016328:NF-kappa B / Q000378:metabolism*; D010051:Ovarian Neoplasms; D017434:Protein Structure, Tertiary; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D011506:Proteins / Q000378:metabolism; D012333:RNA, Messenger / Q000032:analysis; D014407:Tumor Cells, Cultured / Q000166:cytology / Q000187:drug effects / Q000201:enzymology; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*; D051636:X-Linked Inhibitor of Apoptosis Protein
D000970:Antineoplastic Agents; D053446:CASP8 and FADD-Like Apoptosis Regulating Protein; C506386:CFLAR protein, human; D002352:Carrier Proteins; D047908:Intracellular Signaling Peptides and Proteins; D016328:NF-kappa B; D011500:Protein Synthesis Inhibitors; D011506:Proteins; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D051636:X-Linked Inhibitor of Apoptosis Protein; C496866:XIAP protein, human; D003513:Cycloheximide; C505407:CASP3 protein, human; C505530:CASP8 protein, human; C506433:CASP9 protein, human; D053148:Caspase 3; D053181:Caspase 8; D053453:Caspase 9; D020169:Caspases; D020170:Caspase 1