Transformation of SV40-immortalized human uroepithelial cells by 3-methylcholanthrene increases IFN- and Large T Antigen-induced transcripts

To characterize the SV40 - 3MC interaction, we compared human gene expression in these cell lines using a human cancer array and confirmed selected changes by RT-PCR. Many viral Large T Antigen (Tag) expression-related changes occurred in HUC-TC, and it is concluded that SV40 and 3-MC may act synergistically to transform cells. Changes noted in IFP 9-27, 2'-5' OAS, IF 56, MxA and MxAB were typical of those that occur in response to viral exposure and are part of the innate immune response. Because interferon is crucial to innate immune host defenses and many gene changes were interferon-related, we explored cellular growth responses to exogenous IFN-γ and found that treatment impeded growth in tumor, but not immortalized HUC on days 4 - 7. Cellular metabolism however, was inhibited in both cell types. We conclude that IFN-γ metabolic responses were functional in both cell lines, but IFN-γ anti-proliferative responses functioned only in tumor cells.Synergism of SV40 with 3-MC or other environmental carcinogens may be of concern as SV40 is now endemic in 2-5.9% of the U.S. population. In addition, SV40-immortalization is a generally-accepted method used in many research materials, but the possibility of off-target effects in studies carried out using these cells has not been considered. We hope that our work will stimulate further study of this important phenomenon.Simian virus 40 (SV40) was first recognized and isolated during the late 1950's [1] and recently achieved fame because it was carried over inadvertently as live virus into poliovirus vaccine preparations from 1955-1963 in the U.S. and elsewhere [2]. Approximately 60% of the population in the U.S. and abroad was exposed to SV40. Initially this caused little alarm, but the virus was later found to induce mesotheliomas in hamsters [3,4] and afterwards was found in a high percentage of certain types of human cancers, especially mesotheliomas, but not in surrounding tissues [reviewed in [2]]. Discussions and inv