Iroquois homeobox 4 (IRX4) derived micropeptide promotes prostate cancer progression and chemoresistance through Wnt signalling dysregulation

Abstract

Prostate cancer (PCa) is a commonly diagnosed cancer. Genome-wide association studies have implicated Iroquois homeobox 4 (IRX4) in PCa susceptibility, yet its functional roles remain unclear. We discovered a 78-amino acid micropeptide (miPEP, IRX4_PEP1), encoded from the alternative start site within the IRX4 gene. The miPEPs, encoded through short open reading frames (sORFs) have emerged as regulators of diverse biological processes. However, the significance of miPEPs in prostate tumorigenesis and therapy response remains unexplored to date. Here, we demonstrated the unique role of IRX4_PEP1 in PCa. The role of IRX4_PEP1 was evaluated in PCa in vitro via functional assays and comprehensive pathway analysis. The interacting partners of IRX4_PEP1 were identified using an immunoprecipitation assay, and the impact of IRX4_PEP1 on PCa stem cells was assessed through a stem cell enrichment assay. Additionally, the expression of IRX4_PEP1 was evaluated in PCa patient samples for its potential diagnostic and prognostic significance. Here we show IRX4_PEP1 promotes PCa cell proliferation, migration, and invasion by interacting with heterogeneous nuclear ribonucleoprotein K (HNRPK). Notably, IRX4_PEP1 dysregulates Wnt signalling by interacting with Catenin beta 1 (β catenin; CTNB1), elevating PCa stemness markers, and fostering docetaxel resistance. Clinically, IRX4_PEP1 expression is elevated in PCa tissues and correlates positively with disease aggressiveness. CTNNB1, HNRNPK levels, and ssGSEA enrichment score of WNT/CTNB1 signalling correlate positively with IRX4_PEP1 in PCa tissues. These findings highlight IRX4_PEP1 role in PCa stemness and chemoresistance, suggesting it as a therapeutic target and potential diagnostic marker. Prostate cancer (PCa) is a common cancer in men. Our early research identified a small protein, IRX4_PEP1, derived from the Iroquois homeobox 4 (IRX4) gene. The function of this protein was characterised through several assays using PCa cells and PCa stem cells. Our results show that IRX4_PEP1 helps PCa cells to grow and resist treatment by interacting with CTNB1 and HNRPK proteins, affecting the Wnt signalling pathway. Moreover, IRX4_PEP1 increased PCa stem cells and stem cell markers associated with PCa. IRX4_PEP1 levels are higher in PCa tissues and relate to more aggressive disease. This makes IRX4_PEP1 a potential target for PCa treatments and a marker for diagnosis. Fernando et al. investigate a micropeptide encoded in the Iroquois homeobox 4 (IRX4) gene for expression patterns and signalling effects. Their findings suggest it could serve as a therapeutic target and potential diagnostic marker in prostate cancer.