Manganese superoxide dismutase expression in gastric cancer

Manganese superoxide dismutase (Mn-SOD) is a mitochondrial enzyme which participates in the scavenging of superoxide radicals. We examined the expression of Mn-SOD in surgically obtained gastric cancer specimens by RT-PCR and immunohistochemical methods. The mean levels of Mn-SOD mRNA in gastric carcinoma tissue (2186.6 fg/mu g total RNA, n=11) were significantly higher than in those noncancerous tissue (42.3 fg/mu g total RNA). When gastric cancers were classified as intestinal or diffuse in type using Lauren's histological classification, 17 of the 22 intestinal cancers exhibited strong or moderate Mn-SOD expression, By contrast, only one of the Il diffuse type cancers exhibited moderate Mn-SOD staining. These findings indicate that tile intestinal type gastric cancer may be more resistant than the diffuse type cancer to anticancer drugs and radiation therapy, which exert their effects through free radical production.