Overexpression of manganese superoxide dismutase gene changes the metastasis associated-character of the mouse fibrosarcoma, FSa-II

The tumor metastatic ability and tumorigenicity of the mouse fibrosarcoma cell line (FSa-II) were significantly reduced due to overexpression of manganese superoxide dismutase (MnSOD) as reported previously. We investigated changes in the in vitro basic character of FSa-II cells transfected with the human MnSOD cDNA which was employed in the previous studies. FSa-II and the control vector-transfected cell line NEO, had no detectable MnSOD activity. SOD-H, into which MnSOD cDNA was transfected, is the cell line with high MnSOD activity. The malignant phenotype, characterized by serum-independence, was suppressed with elevated MnSOD activity. A quantitative comparison of transferrin receptor (TfR) by flow cytometry showed the amount of TfR on the membrane of SOD-H cells to be significantly less than that on the membrane of NEO cells. The amount of CD44 expression on SOD-H cells was almost the same as that on NEO cells. The results of this study suggest that the overexpression of MnSOD is related to suppression of the malignant phenotype and that changes of iron metabolism may play an important role in this process.