p53/T-antigen complex disruption in T-antigen transformed NIH3T3 fibroblasts exposed to oxidative stress: correlation with the appearance of a Fas/APO-1/CD95 dependent, caspase independent, necrotic pathway
S. Gonin et al., p53/T-antigen complex disruption in T-antigen transformed NIH3T3 fibroblasts exposed to oxidative stress: correlation with the appearance of a Fas/APO-1/CD95 dependent, caspase independent, necrotic pathway, ONCOGENE, 18(56), 1999, pp. 8011-8023
Simian Virus 40 Large T-antigen expressed in NIH3T3 cells increases p53 lev
el and interacts with this tumor suppressor to form large nuclear complexes
, We show here that T-antigen sensitizes NIH3T3 cells to loa doses of the o
xidative stress inducer menadione, This oxidant increased p53 accumulation
and disrupted p53/T-antigen interaction, but not T-antigen/pRb, T-antigen/H
sc70 and p53/Hsc70 complexes; a phenomenon inhibited by the anti-oxidant N-
acetyl-cysteine. Analysis of several p53 downstream gene products revealed
that the level of Fas receptor, which was sharply reduced by T-antigen expr
ession, was drastically increased in response to menadione treatment. Menad
ione also induced a T-antigen dependent cleavage of Fas ligand. Analysis pe
rformed with Fas receptor antagonist antibody and metalloproteinases inhibi
tor revealed that menadione triggers a Fas-dependent death of a fraction of
T-antigen expressing cells, This Fas pathway does not activate caspase 8 o
r 3, probably because of the inhibition induced by T-antigen, and leads to
a necrotic cell death which contributes at least in part to the hypersensit
ivity of T-antigen transformed cells to oxidative stress.