Ornithine Decarboxylase Activity in Cells Acutely and Chronically Transformed by Murine Sarcoma Virus

Ornithine decarboxyase (ODC) activity increases when cells are acutely transformed with murine sarcoma virus (MSV). Three contact inhibited or MSV transformed clones of Balb/3T3 were transformed or supertransformed by MSV or its accompanying non-transforming ‘helper’ virus (MuLV), and the relationships between ODC activity, morphology, virus production and growth rates were examined. Clones isolated from these lines were also studied. All of the virus infected lines released both MSV and MuLV. ODC activities could not be correlated with differences in growth rates. The only consistent relationship was between elevated ODC activity and acute morphological transformation, suggesting that polyamine metabolism plays a crucial role in the transformation process. With time, the elevated ODC activities returned towards baseline levels. Thus ODC activity does not appear to be a useful marker for chronic infection or transformation by type C viruses. The authors thank John Minna, Harold Stull, Herbert Oie, Edward Russelll, Patricia Hefel, and Theresa Gregorio for suggestions and assistance.