Abstract 257: Plasticity of preneoplastic cells drives esophageal squamous cell cancer initiation

Abstract Esophageal squamous cell carcinoma (ESCC) accounts for over 80% of esophageal cancer, with a poor prognosis mainly due to a lack of early-stage symptoms. Early detection of ESCC is challenging due to its origin in the basal cell layer and invasion into the lamina propria upon becoming neoplastic. Thus, understanding the transition mechanism from preneoplasia to neoplasia is crucial for early-stage detection of ESCC before dissemination. To dissect the mechanisms of ESCC preneoplasia and neoplasia, we utilized both spatial and temporal datasets of ESCC in conjunction with a genetically engineered organoid model. For spatial datasets, we conducted comparative analyses of single-cell transcriptomes from healthy esophageal tissues, normal tissue adjacent to cancer (NAC), and paired ESCC tumors to identify distinguishable preneoplastic cells. Notably, unlike normal or ESCC, NAC harbors a distinct preneoplastic cell cluster characterized by the exclusive expression of the CELF2 (CUGBP Elav-Like Family Member 2) gene, high gene copy number variations, cell hyperproliferation, and apoptosis, reminiscent of a 'crisis state'. Consistently, we detected a significant presence of CELF2 positive (+) cells at the stage of inflammation, a very early lesion preceding neoplasia in a temporal model of ESCC development. Copy number variations were also already abundant from the inflammation stage, as we observed in the NAC dataset. Interestingly, both spatial and temporal preneoplastic cells showed decreased scores of TP53 and CDKN2A signaling pathways, of which mutations are observed in 68% of ESCC patients. To recapitulate this phenotype, we employed genetically engineered esophageal organoids and found that the loss of Trp53 and Cdkn2a (PC) generated preneoplastic CELF2+ cells. Intriguingly, these preneoplastic CELF2+ cells exhibited remarkable cellular plasticity in two ways. Firstly, CELF2+ cells of PC display increased stemness mediated by SOX2-driven reprogramming with disrupted normal esophageal cell lineage. Second, CELF2+ cells of PC undergo epithelial-mesenchymal plasticity to generate fibroblast-like cells, releasing cytokines involved in immune remodeling. Consequently, preneoplastic CELF2+ cells developed significant tumors compared to CELF2-negative cells in transplantation assays. Our study identified preneoplastic CELF2+ cells driven by TP53 and CDKN2A loss as pivotal drivers in ESCC initiation via cell-autonomous (cellular reprogramming) as well as non-cell autonomous (immune niche remodeling) processes, proposing CELF2+ cells and their molecular signatures as potential biomarkers and therapeutic targets for early-stage ESCC. Citation Format: Kyung Pil Ko, Jie Zhang, Sohee Jun, Jae-Il Park. Plasticity of preneoplastic cells drives esophageal squamous cell cancer initiation 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 (6Suppl): Abstract nr 257.