title: Reactive oxygen species produced by NAD(P)H oxidase inhibit apoptosis in pancreatic cancer cells.
abstract: One reason why pancreatic cancer is so aggressive and unresponsive to treatments is its resistance to apoptosis. We report here that reactive oxygen species (ROS) are a prosurvival, antiapoptotic factor in pancreatic cancer cells. Human pancreatic adenocarcinoma MIA PaCa-2 and PANC-1 cells generated ROS, which was stimulated by growth factors (serum, insulin-like growth factor I, or fibroblast growth factor-2). Growth factors also stimulated membrane NAD(P)H oxidase activity in these cells. Both intracellular ROS and NAD(P)H oxidase activity were inhibited by antioxidants tiron and N-acetylcysteine and the inhibitor of flavoprotein-dependent oxidases, diphenylene iodonium, but not by inhibitors of various other ROS-generating enzymes. Using Rho(0) cells deficient in mitochondrial DNA, we showed that a nonmitochondrial NAD(P)H oxidase is a major source of growth factor-induced ROS in pancreatic cancer cells. Among proteins that have been implicated in NAD(P)H oxidase activity, MIA PaCa-2 and PANC-1 cells do not express the phagocytic gp91(phox) subunit but express several nonphagocytic oxidase (NOX) isoforms. Transfection with Nox4 antisense oligonucleotide inhibited NAD(P)H oxidase activity and ROS production in MIA PaCa-2 and PANC-1 cells. Inhibiting ROS with the antioxidants, Nox4 antisense, or MnSOD overexpression all stimulated apoptosis in pancreatic cancer cells as measured by internucleosomal DNA fragmentation, phosphatidylserine externalization, cytochrome c release, and effector caspase activation. The results show that growth factor-induced ROS produced by NAD(P)H oxidase (probably Nox4) protect pancreatic cancer cells from apoptosis. This mechanism may play an important role in pancreatic cancer resistance to treatment and thus represent a novel therapeutic target.
authors.affiliation: Departments of Medicine, Veterans Affairs Greater Los Angeles Healthcare System, 11301 Wilshire Boulevard, Los Angeles, CA 90073, USA.
authors.forename: Eva C
authors.initials: EC
authors.lastname: Vaquero
authors.forename: Mouad
authors.initials: M
authors.lastname: Edderkaoui
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Pandol
authors.forename: Ilya
authors.initials: I
authors.lastname: Gukovsky
authors.forename: Anna S
authors.initials: AS
authors.lastname: Gukovskaya
mesh_terms: D000975:Antioxidants / Q000378:metabolism / Q000494:pharmacology; D017209:Apoptosis; D015153:Blotting, Western; D016923:Cell Death; D002454:Cell Differentiation; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000201:enzymology; D053938:DNA Fragmentation; D004272:DNA, Mitochondrial / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D005420:Flavoproteins / Q000378:metabolism; D005434:Flow Cytometry; D006133:Growth Substances / Q000378:metabolism; D006801:Humans; D008562:Membrane Glycoproteins / Q000378:metabolism; D000074662:NADPH Oxidase 2; D000074663:NADPH Oxidase 4; D019255:NADPH Oxidases / Q000378:metabolism*; D009707:Nucleosomes / Q000378:metabolism; D010190:Pancreatic Neoplasms / Q000378:metabolism*; D010587:Phagocytosis; D010718:Phosphatidylserines / Q000737:chemistry / Q000378:metabolism; D020033:Protein Isoforms; D017382:Reactive Oxygen Species / Q000378:metabolism; D013997:Time Factors; D014162:Transfection
chemical_list: D000975:Antioxidants; D004272:DNA, Mitochondrial; D005420:Flavoproteins; D006133:Growth Substances; D008562:Membrane Glycoproteins; D009707:Nucleosomes; D010718:Phosphatidylserines; D020033:Protein Isoforms; D017382:Reactive Oxygen Species; C056558:CYBB protein, human; D000074662:NADPH Oxidase 2; D000074663:NADPH Oxidase 4; D019255:NADPH Oxidases; C498910:NOX4 protein, human