Over-expression of amyloid precursor protein in HEK cells alters p53 conformational state and protects against doxorubicin.
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.
Uberti
Daniela
D
Department of Biomedical Sciences and Biotechnologies, University of Brescia, Brescia, Italy. uberti@med.unibs.it
Cenini
Giovanna
G
Olivari
Luca
L
Ferrari-Toninelli
Giulia
G
Porrello
Emanuela
E
Cecchi
Cristina
C
Pensalfini
Anna
A
Pensafini
Anna
A
Liguri
Gianfranco
G
Govoni
Stefano
S
Racchi
Marco
M
Maurizio
Memo
M
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
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