Comparison between E1A gene from oncogenic and non-oncogenic adenoviruses in cellular transformation (Ad E1A conserved region).

All adenoviruses transform primary BRK cells in vitro, but only cells transformed by oncogenic adenoviruses are tumorigenic for immunocompetent animals. The transforming E1 regions of human Ad 2 and Ad 12 also differ from each other in the frequency in which they can transform BRK cells. We have investigated these properties which can be assigned to the specific domain of the E1A region. For this purpose, chimeric E1A regions between Ad 2 and Ad 12 have been constructed. The efficiency of cell transformation appeared to be determined by the encoding region. The promoter sequences were not important for an efficient cellular transformation although the E1B region cis activated in E1A transcription in both cell transformation and transient expression. We show that sequences located in the E1B promoter were responsible for this effect. In the encoding region the CR 1 domain was essential for the cell transformation frequency.