Activity and expression of superoxide dismutase in human gastric neoplasm

Gastric cancer is the second most common cancer worldwide. The involvement of ROS (reactive oxygen species) in the pathogenesis of gastric malignancies was well know. Many human tumors have shown significant changes in the activity and expression of SOD that might be correlated with survival and clinical-pathological parameters for the prognosis of human carcinoma. Aim of this study is the detection of the MnSOD and CuZnSOD activity and expression in adenocarcinoma, Helicobacter Pilory (HP), autoimmune-atrophic-gastrite (GTA) and healthy tissues. A total of 21 gastric specimens (5 adenocarcinoma, 9 healthy, 5 HP and 2 GTA) collected during endoscopy or resected during surgery were extracted in phosphate buffer and used to determine the SOD activity and expression by spectrophotometric and western blotting assay. As regards to the carcinoma tissues, the trend of the activity of MnSOD is over 9-fold higher and 2.5-fold higher which respect to CuZnSOD in tumors and HP, respectively. On the contrary in healthy tissues and GTA the CuZnSOD shows a similar or major activity than MnSOD and each isoforms represent nearly the 50% of total SOD activity. After immunoblotting detection of SOD isoforms, MnSOD seem lightly more expressed in adenocarcinoma and HP cases respect to healthy tissues and GTA. SOD activity assay can provide a specific and sensible method of analysis that allows to differentiate healthy tissue from tumour, GTA and HP. The ratio of MnSOD and CuZnSOD activities obtained from this preliminary study, seems to be more explicative in the identification of a pathological from a healthy tissue. SOD in GTA samples present a trend similar to healthy tissues, although in HP seems to be nearly to adenocarcinoma. Further researches will be necessary to define the role of SODs in cancer and the use of the activity as a prognostic marker.