MnSOD expression is increased in metastatic gastric cancer

Background. Manganese superoxide dismutase (MnSOD) catalyzes the scavenging of superoxide radicals in order to protect cells from the damage caused by reactive oxygen species. Previous studies implicate MnSOD in cancer progression, but its role in gastric cancer metastasis is poorly understood. Materials and methods. To determine whether MnSOD expression correlates with gastric cancer metastasis, we compared immunostaining for MnSOD in the primary tumors of gastric cancer patients with (n = 15) and without (n = 9) nodal metastases. These patients were matched for risk factors associated with gastric cancer metastasis, such as tumor site, depth, and grade. MnSOD expression was scored positive (increased) if MnSOD staining of tumor cells was more intense than MnSOD staining in corresponding normal gastric epithelial cells. Statistical analyses were via χ² test and Fisher's exact test. Results. MnSOD expression was increased in 14 of the 15 (93%) metastatic tumors, compared to only 4 of the 9 (44%) nonmetastatic tumors (P = 0.015). There was no significant difference in staining when the two groups were compared based on tumor grade (P = 0.70) or depth of tumor cell invasion (T stage) (P = 0.22). Conclusions. MnSOD expression is upregulated in the primary tumors of gastric cancer patients with lymph node metastases. This finding supports an involvement of MnSOD and possibly the reactive oxygen status of the gastric tumor microenvironment in gastric cancer metastasis. (C) 2000 Academic Press.