Simple Summary This study presents data on the immunohistochemical expression of key iron metabolism proteins in non-neoplastic and neoplastic canine testes. Iron is crucial for spermatogenesis, and its regulation in testicular cells is essential for normal function. This study confirms that Sertoli cells and Transferrin Receptor 1 (TfR1) play significant roles in iron uptake in dogs, aligning with findings in humans and mice. However, it highlights a unique expression of nuclear receptor coactivator 4 (NCOA4) in canine Sertoli cells, suggesting a specific role in iron recycling through ferritinophagy. Differences in iron metabolism were observed in various canine testicular tumors. Higher TfR1 and NCOA4 expressions were noted in Leydig cell tumors and diffuse seminomas, indicating a reliance on iron for tumor growth. The altered expression of iron-related proteins in tumors underscores their potential as therapeutic targets. Targeting TfR1 and utilizing iron-modulating therapies shows promise. Further research is needed to explore the therapeutic potential of modulating iron metabolism in canine testicular cancers.Abstract Iron is a key element in spermatogenesis; its metabolic pathway in the testis is strictly regulated. Alterations in iron metabolism are linked to various diseases, including cancer, and changes in iron metabolism-related proteins have been observed in multiple human, mouse and canine tumors. There is limited knowledge about iron metabolism in canine non-neoplastic and neoplastic testes. This study aimed to explore the immunohistochemical expression of molecules involved in iron uptake and storage [Transferrin Receptor 1 (TfR1), ferritin (FTH1), nuclear receptor coactivator 4 (NCOA4)] and PCNA in canine non-neoplastic and neoplastic testicular samples. Non-neoplastic testes showed moderate TfR1 expression in developing germ cells and Sertoli cells, high NCOA4 cytoplasmic immunostaining in the Sertoli cells and occasional cytoplasmic immunopositivity for FTH1 in the spermatogonia and Sertoli cells. In contrast, Leydig cell tumors (LCTs) and Diffuse Type Seminoma (DSEM) exhibited increased expression of TfR1, along with higher PCNA expression, suggesting a higher iron need for proliferation. Intratubular Type Seminoma (ITSEM) showed a higher FTH1 expression, indicating greater iron storage, while the increased NCOA4 expression in the LCTs and DSEM suggested ferritinophagy to release iron for proliferation. Sertoli cell tumors (SCTs) showed only NCOA4 expression. These preliminary findings highlight potential molecular targets for developing new anti-neoplastic treatments in canine testicular tumors.
