title: Loss of functional large T-antigen and free viral genomes from cells transformed in vitro by polyoma virus after passage in vivo as tumor cells.
abstract: We have analyzed the state, arrangement, and expression of polyoma viral DNA sequences in a number of in vitro-transformed Fischer rat cells before and after growth in vivo as tumour cells. When the in vitro lines used to induce the tumors contained only a single insert of viral sequences and did not produce either a full-size 100,000-dalton (100K) large T-antigen or free viral genomes, no differences in the above-mentioned properties were observed. By contrast, in vitro cell lines containing multiple inserts of viral sequences, a functional 100K large T-antigen, and free viral genome induced tumor cells which displayed a reduced number of inserts of viral sequences and which did not produce either a functional 100K large T-antigen or free viral genomes. All of the in vitro lines and their tumor cell derivatives expressed the polyoma virus 55K middle and 22K small T-antigen species. Possible mechanisms for the selection in vivo against cells containing a functional 100K large T-antigen and consequently free viral genomes are discussed.
mesh_terms: D000818:Animals; D000951:Antigens, Neoplasm; D000956:Antigens, Viral; D000957:Antigens, Viral, Tumor; D001483:Base Sequence; D002460:Cell Line; D002472:Cell Transformation, Viral; D004279:DNA, Viral; D005814:Genes, Viral; D008297:Male; D009374:Neoplasms, Experimental / Q000382:microbiology*; D011120:Polyomavirus / Q000235:genetics / Q000276:immunology / Q000502:physiology*; D051381:Rats
chemical_list: D000951:Antigens, Neoplasm; D000956:Antigens, Viral; D000957:Antigens, Viral, Tumor; D004279:DNA, Viral