Rat sequences of the Kirsten and Harvey murine sarcoma virus genomes: nature, origin, and expression in rat tumor RNA

Abstract

Two murine sarcoma viruses, the Kirsten and the Harvey, were isolated by passage of mouse type C leukemia viruses through rats. These sarcoma viruses have genomes containing portions of their parental type C mouse leukemia virus genomes, in stable association with specific rat cellular sequences that we find to be quite likely not those of a rat type C leukemia virus. To determine if these murine sarcoma viruses provide a model relevant to the events occurring in spontaneous tumors, we have hybridized DNA and RNA prepared from rat tumors and normal rat tissues to [3H]DNA prepared from the Kirsten murine sarcoma virus. We have also hybridized these rat tissue nucleic acids to [3H]DNA prepared from a respresentative endogenous rat type C leukemia virus, the WFU (Wistar-Furth). Sarcoma-viral rat cellular sequences and endogenous rat leukemia viral sequences were detected in the DNA of both tumor and normal tissues, with no evidence of either gene amplification or additional sequences being present in tumor DNA. Sarcoma-viral rat cellular sequences and endogenous rat leukemia viral sequences were detected at elevated concentrations in the RNA of many rat tumors and in specific groups of normal tissues.