Transfection and Expression of MnSOD cDNA Decreases Tumor Malignancy of Human Oral Squamous Carcinoma SCC-25 Cells

Abstract

Overexpression of human manganese-containing superoxide dismutase (MnSOD) activity has been demonstrated to suppress malignancy in human melanoma and breast carcinoma cells in vitro and in vivo. To study its effects on human oral squamous carcinoma cells, stable transfection and expression of MnSOD in SCC-25 cells have been conducted. The MnSOD-overexpressing cell clones were shown to have approximately two-to five-fold increased MnSOD activity compared to the wild-type parental- or vector control-transfected cell clones, respectively. Plating efficiency with different concentrations of serum was decreased in the high MnSOD activity cell clones. Soft agar assays demonstrated that the clonogenic fractions of high-expressing MnSOD clones were dramatically reduced. When inoculated in nude mice, tumor growth was markedly inhibited in MnSOD overexpressing cell clones compared with the wild-type or vector control transfected cell lines. Thus, gene therapy of human oral cancer by increasing the expression of MnSOD activity in target cells might be used to prevent or reduce human oral tumor malignancy.

Overview summary

In this study, we have demonstrated that increased manganese-containing superoxide dismutase (MnSOD) gene expression by stable plasmid transfection decreased tumor malignancy both in vitro and in vivo. The antitumor activity of MnSOD or other antioxidant enzymes could be used for human gene therapy after the development of suitable transfection and expression approaches in target tumor cells.