Stimulation of plasminogen activator production by dimethyl sulfoxide in Chinese hamster ovary cells

The production of plasminogen activator activity in an auxotrophic mutant of the Chinese hamster ovary cell line was found be greatly stimulated by low concentrations of dimethyl sulfoxide. The production of both cell-associated and excreted plasminogen activator activities was stimulated maximally by dimethyl sulfoxide at a concentration of 2.5%. The stimulation of plasminogen activator activity production was found to be completely inhibited by actinomycin D and cycloheximide but not by mitomycin C, implying that new protein and RNA syntheses were required for this process. Using specific antibodies against plasminogen activator, the presence of a tissue-type plasminogen activator could only be detected in dimethyl sulfoxide treated cells. The dimethyl sulfoxide induced plasminogen activator production was observed only in a mutant auxotrophic for adenosine, glycine, and thymidine but not in wild-type cells. The ability of dimethyl sulfoxide to induce the synthesis of plasminogen activator was lost when the cells were hybridized with another complementary auxotrophic mutant. This implies that the ability of dimethyl sulfoxide to stimulate the production of plasminogen activator may be related to the auxotrophic mutation in this cell.