title: Genetically recessive mutant of human monocytic leukemia U937 resistant to tumor necrosis factor-alpha-induced apoptosis.
abstract: Tumor necrosis factor-alpha (TNF-alpha) is a cytokine that induces apoptosis in various cell systems by binding to the TNF receptor (TNFR). To study TNF-alpha-induced apoptosis, we isolated and characterized a novel TNF-alpha-resistant variant, U937/TNF clone UA, from human monocytic leukemia U937 cells. The UA cells resist apoptosis induced by TNF-alpha and anti-Fas antibody but not by anticancer drugs, such as VP-16 and Ara-C. Somatic cell hybridization between U937 and UA showed that apoptosis resistance to TNF-alpha in UA was genetically recessive. The hybridization analysis also showed that UA and another recessive mutant clone, UC, belong to different complementation groups in TNF-alpha-induced apoptosis signaling. In UA cells, TNF-alpha-induced disruption of mitochondrial membrane potential and CPP32 activation were abrogated. Expression of TNFR, Fas, and Bcl-2 family proteins was not changed in UA cells. These results suggest that the apoptosis resistant UA cells could have a functional defect in apoptosis signaling from the TNFR to mitochondria and interleukin-1beta converting enzyme (ICE) family protease activation. UA cells could be used to study signaling linkage between cell death-inducing receptor and mitochondria.
authors.affiliation: Institute of Molecular and Cellular Biosciences, University of Tokyo, Japan.
authors.forename: J
authors.initials: J
authors.lastname: Dong
authors.forename: M
authors.initials: M
authors.lastname: Naito
authors.forename: T
authors.initials: T
authors.lastname: Mashima
authors.forename: W H
authors.initials: WH
authors.lastname: Jang
authors.forename: T
authors.initials: T
authors.lastname: Tsuruo
mesh_terms: D017209:Apoptosis / Q000187:drug effects / Q000235:genetics*; D005808:Genes, Recessive; D006801:Humans; D007951:Leukemia, Myeloid / Q000235:genetics* / Q000473:pathology; D009154:Mutation; D015398:Signal Transduction / Q000187:drug effects; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
chemical_list: D014409:Tumor Necrosis Factor-alpha