SUPPRESSION OF TUMOR-METASTASIS BY MANGANESE SUPEROXIDE-DISMUTASE IS ASSOCIATED WITH REDUCED TUMORIGENICITY AND ELEVATED FIBRONECTIN

We have examined the tumorigenicity and the level of extracellular mat rix proteins in fibrosarcoma cells expressing low (SOD-L) and high (SO D-H) MnSOD activities as well as the fibrosarcoma cells transfected wi th the selectable marker alone (NEO). When the cells derived from each tumor cell line were injected into syngeneic mice., the number of tum or cells required to make a tumor in one-half of the mice (TD50) was m arkedly increased in MnSOD-transfected cells. The decrease in the tumo rigenicity of the MnSOD-transfected cells was associated with an incre ase in the fibronectin level. These results support the hypothesis tha t MnSOD is a new type of tumor-suppressor gene.