Supl. 1.

authors

Marcin Chlabicz, Barbara Darewicz, Eugeniusz Malczyk: Klinika Urologii AM w Białymstoku

summary

Introduction.

Renal cell carcinoma (RCC) represents 2-3% of all cancers, with the highest incidence in the more developed countries. The worldwide and European increase in incidence is approximately 2%. Renal cell carcinoma is the most frequently occurring solid lesion within the kidney and comprises different RCC types with specific histopathological and genetic characteristics. According to the WHO classification, three major histological subtypes of RCC exist: conventional (clear cell) (80-90%), papillary (10-15%) and chromofobe (4-5%). There is a 1.5:1 predominance of men over women, with peak incidence occurring between 60 and 70 years of age. Kidney tissue is particularly susceptible

to reactive oxygen species attack which leads to development of cancer. Antioxidants play an important role in defense strategy against reactive oxygen species.

Objectives.

Regarding to above, the aim of our study has been to evaluate the activity of basic antioxidative enzymes as well concentration of non-enzymatic antioxidants and lipid peroxidation in cancer tissue in people with kidney cancer.

Materials and methods.

This study includes 34 patients with kidney cancer. The tumor and morphologically unchanged tissue were collected during surgery. The 10% homogenates were used to examinations. Superoxide dismutase activity was determined spectrophotometrically by measuring inhibition of epinephrine oxidation to adenochrome. Glutathione peroxidise and glutathione reductase activities were measured spectrophotometrically by monitoring the oxidation of NADPH to NADP. The level of sulfhydryl groups was measured spctrophotometrically. Lipid peroxidation product malondialdehyde, ascorbic acid were detected by highperformance liquid chromatography. Statistical analysis was performed using Wilcoxon Matched-Pairs Signed – Ranks Test and values for p<0.05 were considered significant.

Results.

There were no statistical differences between superoxide dismutase activity in cancer tissue and non-tumor tissues. The present study has indicated a significant increase of glutathione peroxidase activity in tumour tissues as compared with controls in all cases. The glutathione peroxidase activity in kidney tumor increased up to 300%. There were no statistical differences among kidney tumor and morphologically unchanged tissue in glutathione reductase activity, although it was decreased in comparison to control tissue. Changes in the activities of antioxidant enzymes were accompanied by changes in non-enzymatic antioxidant parameters. The present study has evidenced a significant decrease in protein SH groups in tumor tissues as compared with controls. It has been shown that the level of vitamin C insignificantly decreased in tumor kidney tissue. The level of the last of lipid peroxidation product - malondialdehyde was increased in average by about 50% in kidney cancer tissue.

Conclusions. In conclusion, the kidney cancer cells are more exposed to oxidative stress than the surrounding noncancerous cells and further understanding of tumour biology from the point of reactive oxygen species may be helpful for establishing a new strategy for cancer therapy.