Andrea Trinchero

Superoxide dismutase in gastric adenocarcinoma: is it a clinical biomarker in the development of cancer?

Abstract Gastric cancer is the second most common cancer worldwide. The involvement of reactive oxygen species (ROS) in the pathogenesis of gastric malignancies is well known. Many human tumours have shown significant changes in the activity and expression of superoxide dismutase (SOD), which might be correlated with clinical–pathological parameters for the prognosis of human carcinoma. The aim of this study is the detection of MnSOD and CuZnSOD activity and their expression in gastric adenocarcinoma and healthy tissues. Gastric samples (adenocarcinoma and healthy tissues) harvested during endoscopy or resected during surgery were used to determine MnSOD and CuZnSOD activity and expression by spectrophotometric and Western blotting assays. The total SOD activity was significantly higher (p<0.05) in healthy mucosa with respect to gastric adenocarcinomas. No differences were found in MnSOD activity and, on the contrary, CuZnSOD activity was significantly lower (p<0.001) in cancer samples with respect to normal mucosa. The rate of MnSOD/CuZnSOD activity in adenocarcinoma was over ninefold higher than that registered in healthy tissues (p<0.05). Moreover, in adenocarcinoma MnSOD activity represented the 83% of total SOD with respect to healthy tissues where the ratio was 52% (p<0.001). On the contrary, in cancer tissues, CuZnSOD activity accounted for only 17% of the total SOD (p<0.001 if compared with the values recorded in normal mucosa). After immunoblotting, MnSOD was more expressed in adenocarcinoma with respect to normal mucosa (p<0.001), while CuZnSOD was similarly expressed in adenocarcinoma and healthy tissues. The SOD activity assay might provide a specific and sensitive method of analysis that allows the differentiation of healthy tissue from tumour tissue. The MnSOD to CuZnSOD activity ratio, and the ratio between these two isoforms and total SOD, presented in this preliminary study might be considered in the identification of cancerous from healthy control tissue.

A spectroscopic and pulse radiolysis study of allopurinol and its copper complex

Abstract Allopurinol (ALP), an anti-hyperuricemic drug, was investigated in the absence and in the presence of Cu(II) ions by vibrational spectroscopy and pulse radiolysis technique in order to obtain some elucidation on the mechanism of its beneficial effect against oxygen free radical-mediated damage. ALP is suggested to give protection to living organisms both by metal chelation and direct scavenging of free radicals. The Raman and IR spectra have been useful to assess the relevant interactions of ALP with Cu(II) ions, which play an important role in the metal catalysed generation of reactive oxygen species. A proposal of the complex structure was performed; the predominant species seems to be a monomeric complex where ALP interacts with the metal by one nitrogen atom of the five-membered ring and the CO group. The pulse radiolysis data have given information on the behaviour of ALP towards radiation-induced radicals. ALP appears to be a good scavenger of OH, giving rise to intermediate transients, namely resonance-stabilised phenoxyl radicals. Also in the presence of Cu(II) ions, ALP reacts fast towards OH radicals.