Tissue and Serum Thioredoxin System and miR-21, miR-23a/b and let-7a as Potential Biomarkers for Brain Tumor Progression

Abstract Thioredoxin system and miRNAs are potential targets for both cancer progression and treatment. However, role of miRNAs and their relation between the expression profile of thioredoxin system in brain tumor progression remains unclear. Thus, in this study we aimed to determine the expression profiles of redox components Trx-1, TrxR-1 and PRDX-1, and oncogenic miR-21, miR-23a/b and let-7a and oncosuppressor miR-125 in different brain tumor tissues and their association with increasing tumor grade. We studied Trx-1, TrxR-1 and PRDX-1 mRNA expression levels by quantitative real-time polymerase chain reaction (qRT-PCR) and protein levels by Western blot and miR-23a, miR-23b, miR-125a, miR-21 and let-7a miRNA expression levels by qRT-PCR in 16 glioma, 15 meningioma, 5 metastatic and 2 benign tumor samples. We also examined Trx-1, TrxR-1 and PRDX-1 protein levels in serum samples of 36 brain tumor patients and 37 healthy volunteers by ELISA. We found that Trx-1, TrxR-1 and PRDX-1 presented high mRNA expression but low protein expression in low-grade brain tumor tissues whereas they showed higher protein expression in sera of patients with low-grade brain tumors. miR-23b, miR-21, miR-23a and let-7a were highly expressed in low-grade brain tumor tissues and positively correlated with the increase in thioredoxin system activity. Our findings showed that Trx-1, TrxR-1 and PRDX-1 and miR-21, miR-23a/b, and let-7a might be used for brain tumor diagnosis in the clinic. Further prospective studies including molecular pathway analyses are required to validate the miRNA/thioredoxin system regulatory axis in brain tumor progression.