Oxidative stress markers 8-OHdG, Trx-1, and Prx6 are expressed in seminoma and are connected to TXNDC2, 3, and 6 expression levels.

Testis-specific thioredoxins (TXNDCs) and oxidative stress have not been studied before in seminoma. We studied the immunohistochemical (IHC) expression of 8-OHdG, Prx6, Trx-1, TXNDC2, 3, and 6 in 25 testicular seminoma and 24 control samples. We retrospectively collected patient details and treatments from hospital records and combined them with IHC results. In normal testis, IHC expression of 8-OHdG, Prx6, TXNDC2, and 3 was higher than in seminoma samples (p<0.001 each), and the absence of n8-OHdG (p=0.002) and nTXNDC2 expression (p=0.044) was clinically associated with elevated lactate dehydrogenase levels. On the contrary, Trx-1 and TXNDC6 were overexpressed in seminoma samples (p=0.035 and p<0.001, respectively), and TXNDC6 was negatively associated with age over 40 (p=0.036). Concordant with the IHC expression, PRDX6 mRNA levels were downregulated with a fold change of -2517.4 (p<0.001), and TXN mRNA levels were upregulated with a fold change of 11637.4 (p=0.008) in seminoma samples compared with healthy controls. The oxidative stress markers studied had a correlation between the nuclear and cytoplasmic localization, a mutual correlation in expression between different markers, and mutual protein-protein interactions according to STRING Enrichment analysis. Our results show that oxidative stress markers and their expression in seminoma differ from that in normal testis tissue. Trx-1 and cTXNDC6 are seemingly overexpressed in seminoma, which might indicate their relevance in seminoma biology.