Am. J. Respir. Cell Mol. Biol.,
Volume 23, Number 6, December, 2000 788-793
Absence of SV40 Large T-Antigen Expression in Human
Mesothelioma Cell Lines
Yannick
Pilatte,
Claire
Vivo,
Annie
Renier,
Laurence
Kheuang,
Anne
Greffard,
and
Marie-Claude
Jaurand
INSERM, Créteil, France
Simian virus (SV) 40 and SV40-like DNA sequences have recently been detected in several types of human tumors, including malignant mesothelioma. However, the presence of
SV40 DNA sequences is not sufficient to account for its possible role in tumor development because the viral proteins must
be expressed and ultimately impair the function of relevant
cell proteins, such as p53 and pRb. In this study we investigated SV40 large T antigen (SV40 Tag) protein expression in
mesothelioma cell lines, established in our laboratory, by
Western blotting, immunoprecipitation, and immunocytochemistry using Tag-specific mouse monoclonal antibodies (mAbs)
Ab-1 (or Pab 419). By Western blotting of cell extracts, none
of the mesothelioma cell lines expressed detectable amounts
of SV40 Tag. However, we found that Ab-1 as well as Pab-101,
another SV 40 Tag-specific mAb, may generate false-positive
signals due to the fact that both antibody preparations are
contaminated by a protein of similar size (90 kD) as SV40 Tag
and react with the various secondary horseradish peroxidase-
conjugated antimouse immunoglobulin Gs tested. The present
study suggests that immunodetection of SV40 Tag protein may
be puzzling because this contaminating Taglike protein may
bind to particular cell structures, thereby generating false-positive signals.
