To extend our study on SV40, we have tested a series of 100 cases of mesothelioma on standard paraffin sections (n=65) and tissue microarrays (n=35). All cases were prepared under the same conditions (fixed 10% buffered formalin and embedded in paraffin). Repeatedly, our results remained negative despite the fact that one-third of the cases had been considered positive with PCR [5]. Using tissue array methodology, we then investigated different types of cancers from lung [small-cell carcinoma (n=15) and non-small-cell carcinoma (n=43)], digestive tract [gastric adenocarcinoma (n=13), colon adenocarcinoma (n=20)], thyroid [papillary carcinoma (n=30), follicular carcinoma (n=10)], prostate [adenocarcinoma (n=21)] and thymus [thymoma (n=13), thymic carcinoma n=6)] for SV40 T-ag. Not a single cell could be detected in these tissues. In parallel, we were unable to detect SV40 T-ag in different tissue arrays of normal organs. In particular, we were unable to detect cells infected with the ubiquitous BK virus in normal kidneys (n=10) and in clear-cell carcinomas (n=12), since the anti-Tag antibody used cross-reacts with this virus.
One important argument against the implication of SV40 in human oncogenesis is that this virus infects monkeys without induction of any type of cancer in this species. Indeed, monkeys are genetically closer to humans than mice. In the latter, the observation of SV40 driven cancers is frequently the result of experiments that induce an up-regulation of viral genes.
1 Department of Pathology, Purpan Hospital and INSERM U563 (CPTP), CHU Purpan, Toulouse; 2 Department of Neurosurgery, Purpan Hospital, Toulouse; 3 Department of Pathology, CHU Caen, France
(*Email: brousset.p{at}chu-toulouse.fr).
References
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