Expression of the simian virus 40 large tumor antigen (Tag) and formation of Tag-p53 and Tag-pRb complexes in human brain tumors.
BACKGROUND
The presence of simian virus 40 (SV40) in human brain tumors remains a controversial issue. Even if SV40 does exist in brain tumors, the questions of whether it is associated with brain tumorigenesis and by what mechanisms are unknown.


METHODS
SV40 large tumor antigen (Tag) was investigated by immunoprecipitation, silver staining, and Western blot analysis in 65 brain tumor cases and 8 cases of normal brain tissue. Tag-p53 and Tag-pRb complexes were screened by immunoprecipitation and Western blot analysis in 18 and 15 Tag positive tumor tissues, respectively.


RESULTS
Tag was found in all 8 cases of ependymoma and 2 cases of choroid plexus papilloma, 90% of pituitary adenoma cases (9 of 10), 73% of astrocytoma cases (11 of 15), 70% of meningioma cases (7 of 10), 50% of glioblastoma multiforme cases (4 of 8), and 33% of medulloblastoma cases (2 of 6). Five oligodendroglioma cases, 1 pineocytoma case, and 8 cases of normal brain tissue were negative for Tag. The Tag-p53 complex was detected in all 18 Tag positive tumors tested and the Tag-pRb complex was detected in all 15 Tag positive tumors tested.


CONCLUSIONS
SV40 Tag not only is expressed in brain tumors; it also can form specific complexes with tumor suppressors p53 and pRb. SV40 is correlated with brain tumorigenesis. The inactivation of p53 and pRb due to the formation of Tag-p53 and Tag-pRb complexes possibly is a significant mechanism in the etiopathogenesis of brain tumors.
Zhen
H N
HN
Department of Neurosurgery, Xijing Hospital, The Fourth Military Medical University, Xi'an, The People's Republic of China.
Zhang
X
X
Bu
X Y
XY
Zhang
Z W
ZW
Huang
W J
WJ
Zhang
P
P
Liang
J W
JW
Wang
X L
XL
D000293:Adolescent; D000328:Adult; D000952:Antigens, Polyomavirus Transforming / Q000096:biosynthesis*; D015153:Blotting, Western; D006801:Humans; D008875:Middle Aged; D011233:Precipitin Tests; D016160:Retinoblastoma Protein / Q000096:biosynthesis*; D016622:Silver Staining; D016159:Tumor Suppressor Protein p53 / Q000096:biosynthesis*
D000952:Antigens, Polyomavirus Transforming; D016160:Retinoblastoma Protein; D016159:Tumor Suppressor Protein p53