title: Down-regulation of procaspase-8 expression by focal adhesion kinase protects HL-60 cells from TRAIL-induced apoptosis.
abstract: We have demonstrated that focal adhesion kinase (FAK)-overexpressed (HL-60/FAK) cells have marked resistance against various apoptotic stimuli such as hydrogen peroxide, etoposide, and ionizing radiation compared with the vector-transfected (HL-60/Vect) cells. HL-60/FAK cells are highly resistant to TRAIL-induced apoptosis, while original HL-60 or HL-60/Vect cells were sensitive. TRAIL at 500 ng/ml induced significant DNA fragmentation, activation of caspase-8 and 3, the processing of a proapoptotic BID, and mitochondrial release of cytochrome c in HL-60/Vect cells, whereas no such events were observed in the HL-60/FAK cells. In particular, the expression of procaspase-8 gene and subsequent cleavage of caspase-8 were markedly reduced in HL-60/FAK cells, while expression of TRAIL-receptor 2 and 3, TRADD, and FADD was equivalent in both types of cells. In HL-60/FAK cells, the phosphoinositide 3 (PI3)-kinase/Akt survival pathway was constitutively activated, accompanied by significant induction of inhibitor-of-apoptosis proteins, XIAP, RIP, and Bcl-XL. The introduction of FAK siRNA in HL-60/FAK cells sensitized them against TRAIL-induced apoptosis, confirming that overexpressed FAK downregulates procaspase-8 expression, which subsequently inhibits downstream apoptosis pathway in the HL-60/FAK cells.
authors.affiliation: Department of Biochemistry, Kyoritsu University of Pharmacy, Shibakoen 1-5-30, Minato-ku, Tokyo 105-8512, Japan.
authors.forename: Yuji
authors.initials: Y
authors.lastname: Tamagiku
authors.forename: Yoshiko
authors.initials: Y
authors.lastname: Sonoda
authors.forename: Mari
authors.initials: M
authors.lastname: Kunisawa
authors.forename: Daiju
authors.initials: D
authors.lastname: Ichikawa
authors.forename: Yayoi
authors.initials: Y
authors.lastname: Murakami
authors.forename: Eriko
authors.initials: E
authors.lastname: Aizu-Yokota
authors.forename: Tadashi
authors.initials: T
authors.lastname: Kasahara
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D051017:Apoptosis Regulatory Proteins; D053181:Caspase 8; D020169:Caspases / Q000378:metabolism*; D002470:Cell Survival; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation / Q000187:drug effects; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D018922:HL-60 Cells; D006801:Humans; D008562:Membrane Glycoproteins / Q000494:pharmacology*; D009097:Multienzyme Complexes / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D053221:TNF-Related Apoptosis-Inducing Ligand; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
chemical_list: D051017:Apoptosis Regulatory Proteins; D008562:Membrane Glycoproteins; D009097:Multienzyme Complexes; D053221:TNF-Related Apoptosis-Inducing Ligand; C505653:TNFSF10 protein, human; D014409:Tumor Necrosis Factor-alpha; D011505:Protein-Tyrosine Kinases; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; C496050:PTK2 protein, human; C505530:CASP8 protein, human; D053181:Caspase 8; D020169:Caspases