High thioredoxin reductase 1 expression in meningiomas undergoing malignant progression.

Thioredoxin (Trx) is a redox active protein that regulates several physiological and biochemical functions, such as growth, apoptosis and cellular defense. The function of Trx itself is regulated by thioredoxin reductase (TrxR). This study was designed to determine the expression of TrxR1 in meningioma tissues of different World Health Organization grades (grade I-III). Meningioma tissues were extracted from the histopathological specimens of 29 patients. These samples included seven histologically normal meningeal tissues that served as a control group and 12 grade I, 12 grade II and 5 grade III meningioma samples. TrxR1 expression was evaluated using quantitative reverse transcription polymerase chain reaction (qRT-PCR) and immunostaining. The proliferative and apoptotic indices of the specimens were investigated by Ki-67 immunostaining and TUNEL assay, respectively. TrxR1 expression, as assessed by qRT-PCR, increased significantly with meningioma grade (p < 0.001). The immunostaining intensity of TrxR1 increased significantly with meningioma grade (p < 0.001). Ki-67 index values increased significantly in accordance with grade progression (p < 0.001). The apoptotic index values were not significantly different in any group (p > 0.05). Trx system seems to be involved in the malignant progression of meningiomas. Further, large studies are required to elucidate the exact role of this system.