Reduced expression of manganese superoxide dismutase mRNA may correlate with invasiveness in esophageal carcinoma

Little is known about the expression and antioxidant function of manganese superoxide dismutase (Mn-SOD) in esophageal squamous cell carcinoma. To determine the significance of Mn-SOD in esophageal squamous cell carcinomas, Mn-SOD mRNA expression was examined in 45 esophageal squamous cell carcinomas and the corresponding normal mucosal tissues by reverse transcription-polymerase chain reaction. The tumor/normal (T/N) ratio of 45 patients with esophageal carcinoma was calculated, and the data were clinicopathologically analyzed. The T/N ratio of Mn-SOD mRNA expression was less than 0.5 in 11 (32.4%) of 34 esophageal carcinoma cases without any preoperative treatments, while none of 11 cases who underwent preoperative chemotherapy showed a T/N ratio of <0.5 (p < 0.05). There was an inverse correlation between the Mn-SOD expression level and the degree of venous invasion (p < 0.05) as well as lymphatic invasion (p < 0.05). Furthermore, poorly differentiated squamous cell carcinoma showed significantly lower Mn-SOD mRNA expression levels than well differentiated carcinoma (p < 0.05). Our results suggest that Mn-SOD mRNA was frequently reduced in esophageal carcinoma when compared to the normal mucosa and the reduced expression levels of Mn-SOD mRNA may lead to an accumulation of superoxide radicals in conjunction with the increased invasiveness of esophageal carcinoma. Copyright (C) 2000 S. Karger AG, Basel.