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ID 20577
file
creator
Yoshikawa, Kyoko
Tsukamoto, Mariko
Tamura, Namiko
subject
PTEN
Akt
Naphthoquinone
Menadione (vitamin K3)
NDC
Medical sciences
abstract
Menadione (vitamin K3) has been shown to activate Erk in several cell lines. This effect has been shown to be due to the activation of EGF receptors (EGFR) as a result of inhibition of some protein tyrosine phosphatases. In the present study, we examined the effects of menadione on Akt in Chinese hamster ovary cells. The phosphorylation of Akt by menadione was not inhibited by AG1478, an inhibitor of EGFR. Menadione inhibited the lipid phosphatase activity of PTEN in a cell-free system. In an intact cell system, menadione inhibited the effect of transfected PTEN on Akt. Thus, one mechanism of its action was considered the accelerated activation of Akt through inhibition of PTEN. This was not the sole mechanism responsible for the EGFR-independent activation of Akt, because menadione attenuated the rate of Akt dephosphorylation even in PTEN-null PC3 cells. The decelerated inactivation of Akt, probably through inhibition of some tyrosine phosphatases, was considered another mechanism of its action.
journal title
Biochimica et Biophysica Acta (BBA) - General Subjects
volume
Volume 1770
issue
Issue 4
start page
687
end page
693
date of issued
2007-04
publisher
Elsevier B.V.
issn
0304-4165
ncid
publisher doi
pubmed id
language
eng
nii type
Journal Article
HU type
Journal Articles
DCMI type
text
format
application/pdf
text version
author
rights
Copyright (c) 2007 Elsevier B.V.
relation url
department
Graduate School of Biomedical Science