Abstract
The cellular gene expression was compared in four Shope carcinoma cell lines, which were derived from a single tumor and possess various potentials for differentiation and tumorigenicity. The E6 and E7 transforming genes of cottontail rabbit papillomavirus were expressed in all these cell lines, highest level of expression being in the most tumorigenic and undifferentiated cell line, where the major histocompatibility complex (MHC) class I expression was the lowest. The MHC class II antigen, which is not expressed on normal epithelial cells, was detected in all the cell lines, but hardly, if at all, on the surface of these cells. The surface expression of the MHC class II antigen could not be induced by the culture supernatant of phytohaemagglutinin-stimulated splenocytes, which increased the surface expression level of the MHC class I antigen of the same cells. These findings suggest that the aberrant expression of the MHC class II antigen in these cells could not be implicated in the immune response against tumors. The c-fos, c-myc and c-H-ras oncogenes were variably expressed in these cell lines, but there was no correlation with tumorigenicity.