Relationship between Rous sarcoma virus-induced expression of membrane antigen aRelationship between Rous sarcoma virus-induced expression of membrane antigen and phenotypic transformation.

Rous sarcoma virus-transformed hamster BHK fibroblasts express a virus-induced cell surface antigen undetectable in cells either transformed by unrelated viruses or infected by transformation-defective strains of Rous sarcoma virus. To clarify whether this antigen plays any role in the process of malignant transformation or is expressed at the cell surface only as a consequence of the acquisition of the transformed phenotype, we have investigated its expression at the cell surface of Rous sarcoma virus-transformed BHK cells treated with dibutyryl cyclic adenosine 3':5'-monophosphate and at the surface of parental BHK cells transiently transformed by the tumor promoter phorbol myristate acetate. In the dibutyryl cyclic adenosine 3':5'-monophosphate-treated cells, in which most of the parameters of the transformed phenotype are reverted to normality, but the product of the transforming gene is still present, virus-induced cell surface antigen is expressed. In the mirror experiment, this antigen is not expressed by phenotypically transformed but genetically normal phorbol myristate acetate-treated cells. It is concluded that the tumor membrane antigen studied is intimately associated with the expression of the function(s) controlled by the transforming gene.