Abstract 5648: Decoding the non-canonical functions of HO-1 in prostate cancer: A nuclear perspective and its association with a neuroendocrine signature

Abstract Previous studies have demonstrated the non-canonical anti-tumor effect of heme-oxygenase 1 (HO-1) in prostate cancer (PCa). Although HO-1 is crucial for free heme degradation, its nuclear expression unveils non-canonical functions beyond its enzymatic function. Understanding the specifics of its non-canonical role remains a critical unmet need. In this study, we identified nuclear interactors of HO-1 and assessed their association with PCa.PCa cells were treated with hemin (80 µM, 24 h), a specific pharmacological inducer of HO-1. Nuclear HO-1 immunoprecipitation and LC-ESI MS/MS analysis identified 11 differential nuclear associated-HO-1 proteins between control and hemin-treated PCa cells (ILF3, ILF2, BCLAF1, SAFB, DDX17, SLC25A5, CASP14, PRDX1, BRIX1, CCDC175, and GPATCH1). Next, we performed an Ingenuity Pathway Analysis (QIAGEN) showing that ILF3 appears as a master regulator of this signature. To assess the clinical relevance of these factors in PCa, we analyzed overall survival (OS), progression-free survival (PFS), relapse free survival (RFS) in multiple PCa datasets (GSE34312, GSE35988, GSE3933, GSE46602, GSE6956, GSE70768, TCGA-PRAD, GSE70770, GSE16560, GSE24136; n=1064). We performed univariable and multivariable analyses for these factors and identified the ones that significantly and independently affected the OS, RFS, PFS. Next, a risk score model was built based on the expression of 9 genes (∑ni=1(Coefi×Expri)) for the GSE70770 dataset using these factors identifying a subpopulation of PCa patients with high-risk of RFS (HR: 7.39 High vs Low score, p<0.0001); ascertaining the critical role of this signature in PCa. To elucidate the association of these factors with the aggressive phenotype of PCa, we analyzed RNA-seq expression data from the MDA-PCa-PDXs series (PCa Patient Derived Xenografts Program; MD Anderson Cancer Center), capturing PCa heterogeneity. Unsupervised clustering analysis revealed that samples with high expression of HO-1 nuclear interactors corresponded to neuroendocrine tumors, negative for androgen receptor staining. Principal Component Analysis identified ILF3 as the most relevant HO-1 interactor driving PDXs’ samples variance, correlating with a significant decrease in relapse-free survival of PCa patients. Further, we used ChIP-Atlas to assess the epigenomic landscapes for these nuclear HO-1 interactors. Results indicated that 40% of HO-1 nuclear interactors were potential transcription regulators. Strikingly, KEGG pathways analyses revealed that their regulomes were significantly associated with neurodegenerative disorders, highlighting their relevance in neural processes. In conclusion, our findings suggest that HO-1 and its nuclear interactors may play a pivotal role in neuroendocrine PCa, shedding light on potential therapeutic targets for this aggressive form of the disease. Citation Format: Seniuk A. Rocio, Agustina Sabater, Pablo Sanchis, Juan Bizzotto, Gastón Pascual, Estefania Labanca, Nicolas Anselmino, Nora Navone, Elba Vazquez, Pia Valacco, Javier Cotignola, Ayelén Toro, Geraldine Gueron. Decoding the non-canonical functions of HO-1 in prostate cancer: A nuclear perspective and its association with a neuroendocrine signature [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5648.