Pirin (PIR) protein belongs to the superfamily of cupin and is highly conserved between eukaryotic and prokaryotic organisms. The Pirin, a product of the PIR gene, is an iron-binding protein acting as a transcriptional coregulator implicated in the regulation of the NF-κB-related transcription via interaction with RelA (p65), as well as BCL3 and NF-κB1 (p50) proteins. It has been reported that PIR is upregulated in various tumors and involved in tumorigenesis. Alterations in Pirin expression were observed in various tumors and under oxidative stress conditions. PIR is a potential druggable target for the therapy of cancers with a high expression level of PIR. PIR might be a promising diagnostic marker for HSPC and CRPC. Furthermore, CRPC treatment strategies targeting PIR may be possible in the future. Identification of antitumor miRNAs, including miRNA passenger strands, may contribute to the development of new diagnostic markers and therapeutic strategies for CRPC.