Abstract 1242: Foxa1/2-dependent epigenomic reprogramming drives lineage switching in lung adenocarcinoma

Abstract

Abstract The ability of cancer cells to alter their identity is essential for tumor survival and progression. Loss of the pulmonary lineage specifier NKX2-1 within KRAS-driven lung adenocarcinoma (LUAD) enhances tumor progression and results in a pulmonary-to-gastric lineage switch that is dependent upon the activity of pioneer factors FoxA1 and FoxA2; however, the underlying mechanism remains largely unknown. Here, we perform transcriptional and epigenetic assays to show that FoxA1/2 reprogram the chromatin landscape of NKX2-1-negative LUAD to facilitate a gastric differentiation program. Using sequential recombination models, we find that FoxA1/2 are required for demethylation of gastric-defining genes after Nkx2-1 deletion. FoxA1 colocalizes with TET3, an enzyme that mediates DNA demethylation, in NKX2-1-negative tumors. Deletion of Foxa1/2 results in loss of TET3 occupancy at key gastric marker genes, indicating that FoxA1/2 recruit TET3 to lineage-specific sites. H3K27ac ChIP-seq and HiChIP show that FoxA1/2 also control the activity of enhancers and promoters as well as their 3D interactions at gastric target genes following NKX2-1 loss. Furthermore, oncogenic KRAS is required for the FoxA1/2-dependent epigenetic reprogramming in NKX2-1-negative LUAD. This work demonstrates the role of FoxA1/2 in rewiring the methylation and histone landscape and cis-regulatory dynamics of NKX2-1-negative LUAD to drive cancer cell lineage switching. Citation Format: Katherine Gillis, Walter Orellana, Emily Wilson, Gabriela Fort, Headtlove Essel Dadzie, Timothy Parnell, Xiaoyang Zhang, Eric Snyder. Foxa1/2-dependent epigenomic reprogramming drives lineage switching in lung adenocarcinoma [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 1242.