Abstract 2704: cGAS-STING drives myeloid inflammation in chromosomally unstable esophageal cancer

Abstract Esophageal adenocarcinoma (EAC) is an aggressive disease characterized by chromosomal instability (CIN), whereby cells continuously acquire chromosomal abnormalities that promote therapeutic resistance, immune evasion and metastasis. CIN in cancers also fuels the misplacement of genomic DNA in the form of structural abnormalities of the nucleus, such as micronuclei (MN), that lead to chronic activation of the cytosolic DNA sensing cGAS-STING pathway. However, how chronic cGAS-STING pathway activation is tolerated and shapes the tumor landscape of CINhigh EAC cancers is poorly understood. Using publicly available RNA-seq and genome sequencing data of EAC tumours and esophageal cancer cell lines as well as a panel of EAC cell lines, we demonstrate that the core cGAS-STING pathway machinery is rarely inactivated in EAC despite high levels of baseline CIN and aneuploidy. Through transcriptomic profiling of an isogenic EAC precursor cell line model of variable CIN and cGASKO/WT EAC cell lines we show that both chronic and transient CIN-driven cGAS-STING activation converge on the expression of CXCR1/2 ligands and other pro-inflammatory cytokines and chemokines rather than typical anti-tumor type I interferon signalling in EAC cells. Indeed, a novel transcriptional signature of cGAS+ micronuclear burden-correlated genes correlates with orthogonal measures of CIN in EAC tumours and esophagogastric cancer cell lines and is associated with an enrichment in myeloid-derived cells as well as poor prognosis. Correspondingly, using multiplexed immunofluorescence (IF) we find that a high preponderance of cGAS+MN and STING expression in human EAC samples is associated with decreased tumor purity, increased myeloid cell and macrophage infiltration, and increased peripheral blood neutrophil counts, indicative of tumor-promoting myeloid inflammation. Ongoing multiplexed IF and single-nuclei RNAseq analysis of cGAS+MNhigh and cGAS+MNlow EAC tumors will further help characterise the components that comprise the CIN EAC tumor microenvironment (TME) and the CIN- and cGAS-STING-dependent cell-cell interactions that govern it. Taken together, our findings provide an explanation for the observed maintenance of cGAS and STING in EAC and identify disruption of cGAS-STING-dependent myeloid cell inflammation and recruitment as a potential therapeutic target for CINhigh EAC. Citation Format: Bruno Beernaert, Erkin Erdal, Rose Clark, Tong Liu, Ester M. Hammond, Eileen E. Parkes. cGAS-STING drives myeloid inflammation in chromosomally unstable esophageal 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 2704.