Selenium level and glutathione-dependent enzyme activities in normal and neoplastic human lung tissues

Selenium, glutathione peroxidase, glutathione reductase and glyoxalase I have been measured in normal and neoplastic human adult lung tissues. Interindividual variations of enzyme activities and selenium content in both tumour and non-tumour tissues were considerable. From the measurements of glutathione peroxidase activity with both hydrogen peroxide and cumene hydroperoxide it was deduced that human tumour and non-tumour lung tissues are devoid of the selenium-independent enzyme. In general, a significant increase in the activity of glutathione peroxidase and glutathione reductase was found in tumour. Glyoxalase I in tumour was as high as in non-tumour samples. Mean selenium concentration tended to be higher in tumour than in non-tumour specimens. When a comparison was made between normal and neoplastic tissue of the same individual, glutathione peroxidase, activity was found to be higher in tumour in 19 cases out of 24 and glutathione reductase in 17 out of 22. In 15 cases out of 18 the selenium levels were found to be higher in tumour. It was concluded that changes in the factors involved in anti-oxidative protection actually occur in human lung tumour tissues.