Assessment of Catalase Activity and Some Trace Element Concentrations in the Blood of Patients with Astrocytoma

Glioma is the most common tumor of the central nervous system, originating from glial cells or their precursors, and accounts for approximately 80% of all malignant brain tumors. Astrocytoma develops as a result of mutations in star-shaped astrocyte cells and constitutes about 75% of all gliomas, among which grade IV astrocytoma and glioblastoma are the most frequently diagnosed. The prognosis for patients diagnosed with this grade of brain tumor is extremely poor, with an overall 5-year survival rate of only 5%. Catalase (CAT) is an enzyme predominantly localized in peroxisomes and plays a crucial role in protecting cells against oxidative stress by preventing the accumulation of hydrogen peroxide (H₂O₂). Elevated CAT expression levels have been reported in various cancer tissues compared to their normal counterparts. In gliomas, catalase appears to be constitutively overexpressed relative to astrocytes. However, the molecular mechanisms regulating CAT expression in astrocytoma remain not fully elucidated. Metal homeostasis is essential for the proper functioning of the brain, which is particularly vulnerable to toxic environmental pollutants. The balance of metals within the brain is maintained through the blood-brain barrier (BBB) and the blood-cerebrospinal fluid barrier. Based on the ability of metals to cross the BBB, it has been hypothesized that prolonged exposure to certain metals may increase the risk of brain cancer. Nevertheless, no clear association between metal exposure and brain cancer development has been established. The aim of the study was to evaluate the correlations between catalase enzymatic activity and the concentrations of selected trace elements in the blood of patients diagnosed with astrocytoma. The study material consisted of blood and plasma samples obtained from patients diagnosed with astrocytoma. Catalase activity was determined in erythrocytes spectrophotometrically. Copper and zinc concentrations were measured in blood plasma, while selenium concentration was determined in whole blood. Trace element concentrations were determined using inductively coupled plasma mass spectrometry (ICP-MS). The experiments showed that catalase activity increased significantly - by 12% seven days after surgical removal of the tumor.