Abstract 4740: Decipher androgen receptor condensate-mediated chromatin remodeling in gastric cancer

Abstract Liquid-liquid phase separation (LLPS) is an intracellular phenomenon where biomolecules, including proteins and nucleic acids, interact to form dense complexes in the cytoplasm or nucleus. This process is crucial for regulating biological functions, including gene expression, signaling pathways, and the cell cycle. Recent studies have revealed a strong association between abnormal LLPS activity and diseases, such as neurodegenerative disorders and cancer. There is a sex difference in the incidence and mortality of gastric cancer (GC), with males exhibiting a higher incidence than females. Sex hormones are among the biological factors contributing to this difference, and the androgen receptor (AR) serves as the key mediator of androgen action. However, its role in transcriptional regulation in GC remains unclear. To address this, we conducted multi-omics assays, including ATAC-seq, CUT&Tag, HiChIP, and RNA-seq, to investigate the AR-related transcriptional regulatory network in GC. Results revealed that chromatin accessibility increased following DHT treatment, and AR target genes were predominantly enriched in pathways related to proliferation, stemness, and metabolism. Furthermore, CUT&Tag analysis indicated that AR binding peaks were primarily located in non-promoter regions, suggesting that AR might bind to enhancer regions. We identified AR-associated typical and super-enhancer (TE/SE) target genes in GC. HiChIP results further confirmed spatial proximity interactions between promoters and enhancers at AR binding sites. In this study, we further investigated the ability of AR to form condensates and observed that AR translocates into the nucleus and forms condensates in the presence of DHT. The mobility of AR-formed foci was confirmed through both in vivo and in vitro experiments. Mutational analysis of key amino acids in AR's structural domains revealed that hydrophobic amino acids, specifically proline and leucine, are critical for AR phase transition. Proximity labeling and IP-MS assays identified SWI/SNF complex subunits and transcriptional coactivators, including BRD4 and MED1, as potential components of AR condensates. To explore the relationship between AR condensation and transcriptional regulation, the AR inhibitor enzalutamide was employed. Enzalutamide disrupted AR condensation and led to the downregulation of genes enriched in proliferation- and stemness-related signaling pathways. The combination of enzalutamide and AU-15330 effectively suppressed cell proliferation, colony formation, and organoid viability. These findings suggest that AR's LLPS capacity plays a critical role in regulating its transcriptional activity. Furthermore, combining SWI/SNF inhibitors with AR antagonists showed synergistic effects in inhibiting GC cell proliferation. Citation Format: Ben Liu, Huahuan Liu, Mengyue Qiu, Kexin Chen. Decipher androgen receptor condensate-mediated chromatin remodeling in gastric cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 4740.