Plasma protein oxidation in patients with brain tumors

Objective: Proteins can undergo numerous covalent changes on exposure to oxidants. Oxidative modification of protein in vivo may affect a variety of cellular functions. Protein oxidation in vivo is a natural consequence of aerobic life. Oxygen radicals and other activated oxygen species generated as byproducts of cellular metabolism or from environmental sources cause modifications to the amino acids of proteins that generally result in loss of protein function/enzymatic activity. It is now well known that reactive oxygen species (ROS) play a key role in human cancer development. Moreover, the brain is especially vulnerable to ROS mediated injury. Method: Therefore, in the present study, protein oxidation was assessed in the plasma of 17 patients with brain tumors and 16 age and gender-matched controls by measuring protein thiols and protein carbonyls spectrophotometrically. Results: There was a significant decrease in protein thiols and carbonyls in malignant cases of brain tumors when compared with the control group. No significant change in protein thiols was noted in benign cases compared to controls. A comparison of levels in benign and malignant cases for both the parameters also showed no significant difference. Discussion: Thus, free radical toxicity does lead to protein oxidation in patients with brain tumors.