A novel stimulus, oncogene, induces expression of CD80 (B7-1) gene

CD80, a cell surface molecule found on antigen-presenting cells which parti cpates in costimulatory signaling, is frequently detected on transformed an d tumor cells, We examined the effect of transformation by v-myc, k-ras, an d SV40 T antigen oncogenes on the expression of a CD80 promoter/luciferase gene as well as the endogenous CD80 promoter gene in murine fibroblast cell lines. All three transformed cell lines were tumorigenic in nude mice, how ever expression of the CD80/luciferase transgene or endogenous CD80 was det ected only in the v-myc and k-ras transformed cell lines. In both cell line s, CD80 expression was first detected more than 30 passages after transform ation. Therefore, induction of CD80 expression was a late event following t ransformation and was not essential for the establishment of the transforme d phenotype.