Abstract 2769: Long non coding RNA H19/cell adhesion molecules circuitry as novel target and diagnostic tool for metastatic prostate cancer

Abstract In the complex tumor biology of prostate cancer (PCa), we previously contributed by demonstrating that estrogen receptor and hypoxia signaling promoted transcription of progression-associated genes. Notably, combined treatment, estrogens plus hypoxia, caused a significant down regulation of the long noncoding RNA H19, one of the most sensitive to these pro-tumoral stimuli. Mechanistically, H19 acts as transcriptional repressor: H19 over-expression decreases E-cadherin (CDH1) level causing epithelial-to-mesenchymal transition whereas H19 reduction promotes the expression of E-cadherin and β4 integrin (ITGB4) switching the tumor dissemination program toward an alternative mechanism, specifically the cohesive metastatic phenotype. We focused on this H19/cell adhesion molecules circuitry by investigating its role as: 1.Novel prognostic biomarker at the time of biopsies. eNOS, HIF2a and β4 integrin expression was evaluated by immunohistochemistry, H19 and CDH1 transcripts by Droplet Digital PCR on FFPE-biopsies in a retrospective cohort of PCa patients [n = 30; Gleason score GS≤ 7(3+4) n= 17, GS ≥7(4+3) n= 13; biochemical, local, or metastatic recurrence defining disease progression (n=8/30; time of recurrence: range 2-6 years)]. Importantly, multivariate analysis of combined biomarkers, named “Bioscore”, defined by the presence of at least 3 among HIF-2α, eNOS, CDH1, β4 integrin ≥cut off or H19≤cut off revealed its prognostic value for progression and Progression-Free Survival determined using the ROC analysis (p=0.003) and Kaplan Meier curve (p= 0.005), respectively. 2.Master regulator of metastatic program in vivo and ex vivo PCa experimental models. Upon H19 silencing, mimicking combined estrogens plus hypoxia treatment, luciferase-positive PC-3 and 22Rv1 cells led to increased E-cadherin and β4 integrin expression, enhanced tumor growth and metastasis formation at bone, lung, and liver in PCa mouse models. Further, treatment with H3K27 demethylase inhibitor, GSK-J4, rescued cell adhesion molecules expression by modulating H3K27me3 level at gene promoters, reduced metastasis number and size, and induced cell death in PCa-derived Organotypic Slice Cultures. Additionally, treatment with JQ1 and dBET6 BET protein family inhibitors) markedly reduced both E-cadherin and β4 integrin levels, cell proliferation and in vivo tumor growth. Intriguingly, H19 silencing increased BRD3 and BRD4 levels, implicating H19 in BRD transcription. Overall, this research enhances our understanding of the molecular mechanisms driving aggressive prostate cancer phenotypes, providing a foundation for new diagnostic and therapeutic strategies in prostate cancer management. Citation Format: Valeria Pecci, Aurora Aiello, Sara De Martino, Cristian Ripoli, Dante Rotili, Francesco Pierconti, Francesco Pinto, Claudio Grassi, Carlo Gaetano, Alfredo Pontecorvi, Lidia Strigari, Antonella Farsetti, Simona Nanni. Long non coding RNA H19/cell adhesion molecules circuitry as novel target and diagnostic tool for metastatic prostate cancer [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 2769.