Iroquois homeobox 4 (IRX4) Derived Micropeptide Promotes Prostate Cancer Progression and Chemoresistance Through Wnt Signaling Dysregulation

Abstract

Abstract Background Genome-wide association studies have implicated Iroquois (IRX) gene clusters in cancer susceptibility, yet their functional roles remain unclear. Micropeptides (miPEPs), short open reading frames (sORFs) encoding small peptides, have emerged as regulators of diverse biological processes. However, the significance of cancer-related miPEPs in tumorigenesis and therapy response remains unexplored. Methods Here, we utilized a Sequential Window Acquisition of all Theoretical Mass Spectra (SWATH-MS/MS)-based proteomic approach to discover miPEPs generated by IRX clusters in prostate, breast, endometrial, and ovarian cancers. The differential expression of identified miPEPs was measured across different cancer subtypes, grades, and stages, and identified IRX4_PEP1, a miPEP derived from IRX4 as a promising candidate. The role of IRX4_PEP1 was evaluated in prostate cancer (PCa) in vitro via functional assays and comprehensive pathway analysis. Additionally, the expression of IRX4_PEP1 was evaluated in PCa patient samples for it's potential diagnostic and prognostic significance. Results We identified 17 miPEPs from IRX clusters in prostate, breast, endometrial, and ovarian cancers. Among these, IRX4_PEP1 exhibited significant roles in PCa progression. IRX4_PEP1 promoted PCa cell proliferation, migration, and invasion by interacting with heterogeneous nuclear ribonucleoprotein K (hnRNPK). Notably, IRX4_PEP1 disrupted Wnt signaling by interacting with Catenin beta 1 (β catenin; CTNB1), elevating PCa stemness markers, and fostering docetaxel resistance. Clinically, IRX4_PEP1 expression was elevated in PCa tissues, correlating positively with disease aggressiveness. CTNB1 and hnRNPK levels also correlated positively with IRX4_PEP1 in PCa tissues. Conclusions These findings highlight IRX4_PEP1's role in PCa stemness and chemoresistance, suggesting it as a therapeutic target and potential diagnostic marker. This study unveils the intricate links between miPEPs, gene clusters, and cancer progression, offering insights for innovative interventions.