Abstract
In an experimental pulmonary metastasis model employing Meth A cells, significant and dose-dependent inhibition was observed by intravenous pre-administration of PC-SOD. Unmodified SOD (U-SOD) was also effective, but was less potent than PC-SOD. The activity of endogenous SOD remained unchanged immediately after tumor cell implantation. In while, PC-SOD significantly increased the SOD activity compared with that of the control group. U-SOD also increased the activity, which was more quickly reduced. In vitro addition of PC-SOD dose dependently suppressed cell growth of Meth A, in while SOD had little effect. In addition, the combination of PC-SOD and S-nitroso-N-acetyl-D, L-penicillamine (SNAP), a nitric oxide (NO) generating agent, had additive effect. It was also found that PC-SOD prevented the reduced levels of NOx in the lung following tumor cell inoculation. Therefore, there might be a possibility that PC-SOD was more useful to prevent the excessive formation of superoxide anions (O2-) and peroxynitrite (ONOO-) to elicit cell damage and facilitate metastatic incidence.
