Peroxidasin expression is increased in intratumoural capillaries and in proximal tubular cells adjacent to clear cell renal cell carcinoma.

Peroxidasin (PXDN), is a heme peroxidase with a critical role in the crosslinking of type IV collagen, being essential for basement membrane integrity. Overexpression of PXDN has been associated with poor clinical outcomes in many cancers; however, little is currently known about its role in renal cell carcinoma (RCC). In this study, we characterized the expression of PXDN in tumour tissue and adjacent non-neoplastic tissue from cases of clear cell renal cell carcinoma (ccRCC), chromophobe RCC (chRCC), and renal oncocytoma using immunohistochemistry. Our results revealed increased PXDN expression in the intratumoural capillaries of ccRCC compared to other tumour types, including oncocytoma. Additionally, there was a notable increase in PXDN expression in the proximal tubular epithelial cells of non-neoplastic adjacent parenchyma in ccRCC cases compared to the same region in oncocytomas. These findings suggest, for the first time, that PXDN may play a role in tumour angiogenesis, potentially promoting metastases and malignancy. Furthermore, PXDN may be involved in the crosstalk between the tumour and adjacent tissues, a mechanism warranting further investigation.