title: The nuclear factor κB family member RelB facilitates apoptosis of renal epithelial cells caused by cisplatin/tumor necrosis factor α synergy by suppressing an epithelial to mesenchymal transition-like phenotypic switch.
abstract: Cis-diamminedichloroplatinum(II) (cisplatin)-induced renal proximal tubular apoptosis is known to be preceded by actin cytoskeleton reorganization, in conjunction with disruption of cell-matrix and cell-cell adhesion. In the present study, we show that the proinflammatory cytokine tumor necrosis factor α (TNF-α) aggravated these cisplatin-induced F-actin and cell adhesion changes, which was associated with enhanced cisplatin-induced apoptosis of immortalized proximal tubular epithelial cells. TNF-α-induced RelB expression and lentiviral small hairpin RNA (shRNA)-mediated knockdown of RelB, but not other nuclear factor κB members, abrogated the synergistic apoptosis observed with cisplatin/TNF-α treatment to the level of cisplatin-induced apoptosis. This protective effect was associated with increased stress fiber formation, cell-matrix, and cell-cell adhesion in the shRNARelB (shRelB) cells during cisplatin/TNF-α treatment, mimicking an epithelial-to-mesenchymal phenotypic switch. Indeed, gene array analysis revealed that knockdown of RelB was associated with upregulation of several actin regulatory genes, including Snai2 and the Rho GTPase proteins Rhophilin and Rho guanine nucleotide exchange factor 3 (ARHGEF3). Pharmacological inhibition of Rho kinase signaling re-established the synergistic apoptosis induced by combined cisplatin/TNF-α treatment of shRelB cells. In conclusion, our study shows for the first time that RelB is required for the cisplatin/TNF-α-induced cytoskeletal reorganization and apoptosis in renal cells by controlling a Rho kinase-dependent signaling network.
authors.affiliation: Division of Toxicology, Leiden Academic Centre for Drug Research, Leiden University, Gorlaeus Laboratory, Einsteinweg 55, 2333 CC Leiden, The Netherlands.
authors.forename: Giulia
authors.initials: G
authors.lastname: Benedetti
authors.forename: Michiel
authors.initials: M
authors.lastname: Fokkelman
authors.forename: Kuan
authors.initials: K
authors.lastname: Yan
authors.forename: Lisa
authors.initials: L
authors.lastname: Fredriksson
authors.forename: Bram
authors.initials: B
authors.lastname: Herpers
authors.forename: John
authors.initials: J
authors.lastname: Meerman
authors.forename: Bob
authors.initials: B
authors.lastname: van de Water
authors.forename: Marjo
authors.initials: M
authors.lastname: de Graauw
mesh_terms: D000199:Actins / Q000235:genetics / Q000378:metabolism; D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D002448:Cell Adhesion / Q000187:drug effects / Q000235:genetics; D002478:Cells, Cultured; D002945:Cisplatin / Q000494:pharmacology*; D004357:Drug Synergism; D004847:Epithelial Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D058750:Epithelial-Mesenchymal Transition / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D006801:Humans; D007687:Kidney Tubules, Proximal / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D051379:Mice; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D022502:Stress Fibers / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D051841:Transcription Factor RelB / Q000235:genetics / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*; D015854:Up-Regulation / Q000187:drug effects; D054460:rho-Associated Kinases / Q000235:genetics / Q000378:metabolism
chemical_list: D000199:Actins; D016328:NF-kappa B; C497594:Relb protein, mouse; D014409:Tumor Necrosis Factor-alpha; D051841:Transcription Factor RelB; D054460:rho-Associated Kinases; D002945:Cisplatin