title: Catalase expression in MCF-7 breast cancer cells is mainly controlled by PI3K/Akt/mTor signaling pathway.
abstract: Catalase is an antioxidant enzyme that catalyzes mainly the transformation of hydrogen peroxide into water and oxygen. Although catalase is frequently down-regulated in tumors the underlying mechanism remains unclear. Few transcription factors have been reported to directly bind the human catalase promoter. Among them FoxO3a has been proposed as a positive regulator of catalase expression. Therefore, we decided to study the role of the transcription factor FoxO3a and the phosphatidylinositol-3 kinase (PI3K) signaling pathway, which regulates FoxO3a, in the expression of catalase. To this end, we developed an experimental model of mammary breast MCF-7 cancer cells that acquire resistance to oxidative stress, the so-called Resox cells, in which catalase is overexpressed as compared with MCF-7 parental cell line. In Resox cells, Akt expression is decreased but its phosphorylation is enhanced when compared with MCF-7 cells. A similar profile is observed for FoxO3a, with less total protein but more phosphorylated FoxO3a in Resox cells, correlating with its higher Akt activity. The modulation of FoxO3a expression by knockdown and overexpression strategies did not affect catalase expression, neither in MCF-7 nor in Resox cells. Inhibition of PI3K and mTOR by LY295002 and rapamycin, respectively, decreases the phosphorylation of downstream targets (i.e. GSK3β and p70S6K) and leads to an increase of catalase expression only in MCF-7 but not in Resox cells. In conclusion, FoxO3a does not appear to play a critical role in the regulation of catalase expression in both cancer cells. Only MCF-7 cells are sensitive and dependent on PI3K/Akt/mTOR signaling.
authors.affiliation: Université catholique de Louvain, Louvain Drug Research Institute, Toxicology and Cancer Biology Research Group, Brussels, Belgium.
authors.forename: Christophe
authors.initials: C
authors.lastname: Glorieux
authors.affiliation: Université catholique de Louvain, Pole of Cardiovascular Research, Institut de Recherche Expérimentale et Clinique, Brussels, Belgium.
authors.forename: Julien
authors.initials: J
authors.lastname: Auquier
authors.affiliation: Université Bordeaux-Segalen, Inserm U1053, Bordeaux, France.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Dejeans
authors.affiliation: Université catholique de Louvain, Louvain Drug Research Institute, Toxicology and Cancer Biology Research Group, Brussels, Belgium.
authors.forename: Brice
authors.initials: B
authors.lastname: Sid
authors.affiliation: Université catholique de Louvain, de Duve Institute, Experimental Medicine Unit, Brussels, Belgium.
authors.forename: Jean-Baptiste
authors.initials: JB
authors.lastname: Demoulin
authors.affiliation: Université catholique de Louvain, Pole of Cardiovascular Research, Institut de Recherche Expérimentale et Clinique, Brussels, Belgium.
authors.forename: Luc
authors.initials: L
authors.lastname: Bertrand
authors.affiliation: Université catholique de Louvain, Louvain Drug Research Institute, Toxicology and Cancer Biology Research Group, Brussels, Belgium.
authors.forename: Julien
authors.initials: J
authors.lastname: Verrax
authors.affiliation: Université catholique de Louvain, Louvain Drug Research Institute, Toxicology and Cancer Biology Research Group, Brussels, Belgium; Facultad de Ciencias de la Salud, Universidad Arturo Prat, Iquique, Chile. Electronic address: pedro.buccalderon@uclouvain.be.
authors.forename: Pedro Buc
authors.initials: PB
authors.lastname: Calderon
mesh_terms: D001943:Breast Neoplasms / Q000201:enzymology / Q000473:pathology; D002374:Catalase / Q000096:biosynthesis*; D005260:Female; D015971:Gene Expression Regulation, Enzymologic; D006801:Humans; D061986:MCF-7 Cells; D018384:Oxidative Stress / Q000187:drug effects / Q000502:physiology; D058539:Phosphatidylinositol 3-Kinase / Q000502:physiology*; D000081082:Phosphoinositide-3 Kinase Inhibitors; D051057:Proto-Oncogene Proteins c-akt / Q000037:antagonists & inhibitors / Q000502:physiology*; D015398:Signal Transduction / Q000502:physiology*; D020123:Sirolimus / Q000494:pharmacology; D058570:TOR Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000502:physiology*
chemical_list: D000081082:Phosphoinositide-3 Kinase Inhibitors; C577219:CAT protein, human; D002374:Catalase; C546842:MTOR protein, human; D058539:Phosphatidylinositol 3-Kinase; D051057:Proto-Oncogene Proteins c-akt; D058570:TOR Serine-Threonine Kinases; D020123:Sirolimus
keywords: Akt; Breast cancer; Catalase; FoxO3a; HEPES; LY294002; MOPS; Oxidative stress; PI3K; Penicillin; Rapamycin; Sodium orthovanadate; Sodium β-glycerophosphate; Tetrasodium pyrophosphate; [γ-(32)P]ATP-Mg; mTOR; streptomycin