1468P - cGAS-driven inflammation in chromosomally unstable oesophagogastric adenocarcinoma

Background

Oesophageal adenocarcinoma (OAC) is characterised by chromosomal instability (CIN) resulting in therapeutic resistance and metastasis. CIN in cancers results in formation of micronuclei and subsequent activation of cGAS-STING signalling pathway. However, how chronic cGAS activation is tolerated and impacts the tumour landscape of CIN^high OAC is poorly understood.

Methods

We developed novel OAC cell lines and cGAS^KO cells for transcriptomic profiling. Multiplex immunfluorescence was performed on pre-neoadjuvant chemotherapy biopsies and resection specimens for cGAS/STING and myeloid infiltration. Co-culture experiments used PBMCs and conditioned media. Single-nuclei RNA-seq data was obtained from n=3 CIN^high and n=3 CIN^low tumour biopsies stratified by cGAS⁺ micronuclei score.

Results

Transcriptomic profiling demonstrated 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 OAC cells. Indeed, a novel transcriptional signature of cGAS⁺ micronuclear burden-correlated genes correlates with orthogonal measures of CIN in OAC tumours 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 OAC samples is associated with decreased tumor purity, increased myeloid cell and macrophage infiltration, distinct extracellular matrix and increased peripheral blood neutrophil counts, indicative of tumor-promoting myeloid inflammation. snRNAseq revealed upregulation of inflammatory signalling in CIN^high tumours with distinct myeloid and fibroblast phenotypes.

Conclusions

Ongoing snRNAseq analysis will characterise 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 OAC and identify disruption of cGAS-STING-dependent myeloid cell inflammation and recruitment as a potential therapeutic target for CIN^high OAC.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

The authors.

Funding

Cancer Research UK; Wellcome Trust; BRC.

Disclosure

All authors have declared no conflicts of interest.