PD37-01 LOSS OF FOXA1 RESULTS IN GENOME-WIDE EPIGENETIC REPROGRAMMING AND ACTIVATION OF INTERFERON-RESPONSE GENES INCLUDING CD274 /PD-L1

Abstract

You have accessJournal of UrologyBladder Cancer: Basic Research & Pathophysiology I (PD37)1 Sep 2021PD37-01 LOSS OF FOXA1 RESULTS IN GENOME-WIDE EPIGENETIC REPROGRAMMING AND ACTIVATION OF INTERFERON-RESPONSE GENES INCLUDING CD274/PD-L1 Hironobu Yamashita, Wenhuo Hu, Joshua Warrick, Vonn Walter, Jenna Craig, Hikmat Al-Ahmadie, and David Degraff Hironobu YamashitaHironobu Yamashita More articles by this author , Wenhuo HuWenhuo Hu More articles by this author , Joshua WarrickJoshua Warrick More articles by this author , Vonn WalterVonn Walter More articles by this author , Jenna CraigJenna Craig More articles by this author , Hikmat Al-AhmadieHikmat Al-Ahmadie More articles by this author , and David DegraffDavid Degraff More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000002047.01AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Forkhead Box A1 (FOXA1) is a pioneer transcription factor (TF) critical in epigenetic regulation of chromatin state and cell fate determination. Reduced FOXA1 is an independent predictor of poor overall survival in bladder cancer (BC) patients. However, the impact of FOXA1 loss on chromatin epigenetics in BC is unknown. Therefore, we determined the impact of FOXA1 KO on epigenetic modification of chromatin and associated gene expression. Our integrated analysis identifies FOXA1 as an important regulator of chromatin epigenetic state and expression of immune checkpoint (IC) targets in BC. METHODS: We used CRISPR/Cas9 to delete FOXA1 in the human luminal BC cells. We performed RNA-seq and Chip-seq for H3K27ac, an epigenetic mark of active enhancers/promoters. Motif and GSEA analysis of RNA/Chip-seq were performed to identify FOXA1 KO-induced epigenetic differences influencing gene expression. Western blotting (WB)/qPCR confirmed FOXA1-mediated CD274/PD-L1 expression. In silico analysis of TCGA data also confirmed relevance to human disease. RESULTS: We identified 8,230 differentially expressed genes in FOXA1 KO. Notably, GSEA identified IFNɑ/ɣ gene signatures as enriched in FOXA1 KO. As expected, the majority of differences in H3K27ac across genomic areas in FOXA1 KO were mapped to intergenic (n=6,250 peaks; 42% of total peaks) and intronic (n=6,490; 43%) regions. In addition, differential H3K27ac levels were also mapped to proximal promoters (n=1,306; 9%) as well as within gene bodies (n=931; 6%). Integrated analysis of RNA/ChIP-seq shows changes in gene expression are mirrored by differences in H3K27ac. Motif analysis of DNA sequence enriched for H3K27ac identified significant increases in TF binding motifs including the interferon (IFN) sensitive response element (ISRE) and IFN response factors such as IRF1. Moreover, we identified increased H3K27ac of regulatory elements as being associated with several upregulated ISGs in FOXA1 KO. These include ISG15, IFIT2/3, IFI44L and CD274/PD-L1. WB/qPCR confirmed upregulation of several ISGs, including CD274/PD-L1 following FOXA1 KO. Analysis of TCGA data confirmed an inverse relationship between FOXA1 and CD274 in BC and other cancers. CONCLUSIONS: In summary, we provide evidence of widespread epigenetic reprogramming after FOXA1 KO in BC cells. Additionally, we provide evidence that epigenetic changes contribute to activation of a global IFN-dominant signature, including CD274/PD-L1 in a cancer cell-intrinsic manner in FOXA1 KO. Source of Funding: Supported in part by RSG 17-233–01-TBE from the American Cancer Society (D.J.D.), The W.W. Smith Charitable Trust (D.J.D.), the Ruth Heisey Cagnoli Endowment in Urology at Penn State College of Medicine and the Bladder Cancer Support Group at Penn State Health © 2021 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 206Issue Supplement 3September 2021Page: e655-e655 Advertisement Copyright & Permissions© 2021 by American Urological Association Education and Research, Inc.MetricsAuthor Information Hironobu Yamashita More articles by this author Wenhuo Hu More articles by this author Joshua Warrick More articles by this author Vonn Walter More articles by this author Jenna Craig More articles by this author Hikmat Al-Ahmadie More articles by this author David Degraff More articles by this author Expand All Advertisement Loading ...