Abstract The oncogenic potential of some transformed cell lines has been shown in animal tumor models to be the direct result of MHC class I mRNA suppression. Rodent cells established with the highly oncogenic human adenovirus type 12 exhibit greatly reduced levels of class I Ag compared with cells derived with the nononcogenic adenovirus type 5. By using seven independently derived adenovirus-transformed cell lines, we have investigated the mechanism responsible for down-regulation of class I RNA expression. In all adenovirus 12-transformed cells examined, class I RNA suppression was the result of a block in transcription initiation. Highly oncogenic cell lines derived from a spontaneous melanoma and a chemically induced sarcoma also showed greatly reduced transcription of class I genes. We conclude that suppression of MHC class I RNA in a variety of highly oncogenic cells results largely from a substantial decrease in transcription initiation.

Lassam, N., & Jay, G. (1989). Suppression of MHC class I RNA in highly oncogenic cells occurs at the level of transcription initiation. The Journal of Immunology, 143(11), 3792–3797.