title: Recombinant retroviruses that transduce individual polyoma tumor antigens: effects on growth and differentiation.
abstract: We have constructed infectious retroviral vectors, derived from Moloney murine leukemia virus, that efficiently transduce the polyoma virus tumor (T) antigens individually. The parental vector we have chosen [pZIP-NeoSV(X)1] expresses a dominant selectable marker for neomycin resistance and is a shuttle vector capable of propagation in both eukaryotic and prokaryotic cells, thus facilitating its use in structure-function studies. To address the relationship between polyoma T-antigen tumorigenesis and the effects of individual T antigens on growth control and differentiation, we used these vectors to introduce and stably express large, middle-sized, or small T antigens into mouse fibroblasts and preadipocytes. All cDNAs introduced into the vector are expressed stably even in the absence of selective pressure. The stable expression of small T antigen is noted particularly because cell lines expressing small T antigen have not been readily available prior to the use of retroviral vectors. Small T antigen-induced increase in saturation density of NIH 3T3 cells can be scored on the basis of the morphology of drug-resistant colonies. Middle-sized T antigen eliminates the growth requirement of NIH 3T3 cells for epidermal growth factor in a defined medium and permits growth in platelet-poor plasma, indicating elimination of the platelet-derived growth factor requirement as well. Large T antigen suppresses mouse preadipocyte (3T3-F442A) differentiation. These vectors and these functional assays of T-antigen activity permit genetic analysis of the relationship between tumorigenesis by T antigens and the alteration of cellular growth and differentiation.
mesh_terms: D000273:Adipose Tissue / Q000166:cytology; D000818:Animals; D000957:Antigens, Viral, Tumor / Q000235:genetics*; D002453:Cell Cycle; D002454:Cell Differentiation; D002460:Cell Line; D005786:Gene Expression Regulation; D005814:Genes, Viral; D005822:Genetic Vectors; D006133:Growth Substances / Q000502:physiology; D051379:Mice; D011120:Polyomavirus / Q000235:genetics*; D012190:Retroviridae / Q000235:genetics*; D014161:Transduction, Genetic
chemical_list: D000957:Antigens, Viral, Tumor; D006133:Growth Substances