Suppression of the simian virus 40 tumorigenic phenotype in hybrid cells formed from simian virus 40- and adenovirus 2-transformed hamster embryo cells.

Hamster cells transformed by adenovirus 2 (Ad2) or simian virus 40 (SV40) have different tumorigenic phenotypes. In the present study, somatic cell hybrids formed from Ad2- and SV40-transformed hamster cells were used to determine whether possible interactions between the integrated viral genomes would influence the tumorigenic phenotype of hybrid transformed cells. These somatic cell hybrids were of two types, one expressing both Ad2 and SV40 T-antigens and the other expressing only SV40 T-antigens. Tumor induction by hybrid cells that expressed both Ad2 and SV40 T-antigens was reduced in adult syngeneic hamsters and abrogated in adult allogeneic hamsters. These results indicate that the tumorigenic phenotype of transformed somatic cell hybrids that contain both the Ad2 and SV40 genome is governed by the genetic expression of Ad2. This expression may alter the ability of SV40-transformed hamster cells to resist the immunologically nonspecific defenses of the host.