title: Over-expression of amyloid precursor protein in HEK cells alters p53 conformational state and protects against doxorubicin.
abstract: Here we show that human embryonic kidney (HEK) cells stably transfected with amyloid precursor protein (HEK-APP), expressed a conformational mutant-like and transcriptionally inactive p53 isoform, and turned out to be less sensitive to the cytotoxin doxorubicin in comparison with untransfected cells. Treatment of HEK-APP cells with gamma- and beta-secretase inhibitors prevented generation of unfolded, mutant-like p53 isoform and made the cells vulnerable to doxorubicin as untransfected cells. Changes in p53 conformational state and reduced sensitivity to doxorubicin were also found in untransfected HEK cells after exposure to nanomolar concentrations of beta-amyloid (Abeta) and these effects were antagonized by vitamin E. The modulator effects of Abeta on p53 conformational state were, at least in part, due to the intracellular peptides as (i) treatment of HEK-APP cells with an antibody that sequestered extracellular Abeta did not modify the capability of the cells to express the mutant-like p53 isoform; (ii) in the presence of 1% serum exogenous Abeta peptide crossed the plasma membrane, as demonstrated by confocal analysis and ELISA, and induced p53 conformational change; and (iii) in the presence of 10% serum Abeta did not enter the cells and consequently did not influence the p53 conformational state.
authors.affiliation: Department of Biomedical Sciences and Biotechnologies, University of Brescia, Brescia, Italy. uberti@med.unibs.it
authors.forename: Daniela
authors.initials: D
authors.lastname: Uberti
authors.forename: Giovanna
authors.initials: G
authors.lastname: Cenini
authors.forename: Luca
authors.initials: L
authors.lastname: Olivari
authors.forename: Giulia
authors.initials: G
authors.lastname: Ferrari-Toninelli
authors.forename: Emanuela
authors.initials: E
authors.lastname: Porrello
authors.forename: Cristina
authors.initials: C
authors.lastname: Cecchi
authors.forename: Anna
authors.initials: A
authors.lastname: Pensalfini
authors.forename: Anna
authors.initials: A
authors.lastname: Pensafini
authors.forename: Gianfranco
authors.initials: G
authors.lastname: Liguri
authors.forename: Stefano
authors.initials: S
authors.lastname: Govoni
authors.forename: Marco
authors.initials: M
authors.lastname: Racchi
authors.forename: Memo
authors.initials: M
authors.lastname: Maurizio
mesh_terms: D016229:Amyloid beta-Peptides / Q000378:metabolism / Q000494:pharmacology; D016564:Amyloid beta-Protein Precursor / Q000096:biosynthesis* / Q000235:genetics; D000970:Antineoplastic Agents / Q000494:pharmacology; D002460:Cell Line; D004317:Doxorubicin / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D006801:Humans; D007668:Kidney / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D010446:Peptide Fragments / Q000378:metabolism / Q000494:pharmacology; D011487:Protein Conformation / Q000187:drug effects; D017510:Protein Folding; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*; D014810:Vitamin E / Q000494:pharmacology
chemical_list: D016229:Amyloid beta-Peptides; D016564:Amyloid beta-Protein Precursor; D000970:Antineoplastic Agents; D010446:Peptide Fragments; D016159:Tumor Suppressor Protein p53; C078592:amyloid beta-protein (1-40); C075222:amyloid beta-protein (1-42); D014810:Vitamin E; D004317:Doxorubicin