Carcinogen-mediated amplification of viral DNA sequences in simian virus 40-transformed Chinese hamster embryo cells.

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Abstract
Exposure of SV-40-transformed Chinese hamster embryo cells to various chemical and physical carcinogens induced SV-40 DNA synthesis. Although the carcinogen-mediated amplification of SV-40 DNA is regulated by the viral A gene, the induction of viral DNA synthesis does rot result in the rescue of infectious virus or the formation of complete viral DNA molecules. Instead, a heterogenous collection of DNA molecules containing SV-40 sequences was generated by treatment with 7,12-dimethylbenz[a]anthracene. Restriction enzyme analysis of the amplified DNA molecules in the Hirt supernatant showed that not all sequences in the integrated SV-40 inserts are present. The possibility that amplification of SV-40 sequences is a reflection of a general gene-amplification phenomenon mediated carcinogens is discussed.