Abstract 2170: Effects of folic acid supplementation on early stages of colitis-associated carcinogenesis

Abstract Ulcerative colitis (UC) is a chronic inflammatory bowel disease (IBD) characterized by persistent mucosal inflammation extending throughout the colon. Due to compromised intestinal surface integrity and the prolonged use of medication, individuals with UC often develop a folate deficiency, requiring folic acid (FA) supplementation. Prior findings from this group indicate that FA supplementation, at clinically relevant levels, promotes UC-associated dysplasia. Supplementation with FA resulted in an increased multiplicity of dysplasia and a significant elevation in the expression of several inflammatory genes (e.g. IL-6, Cox-2, Iκκ-β) within the colonic mucosa of mice with UC. Genome-wide expression profiling of normal and dysplastic colonic epithelial cells from mice treated with different doses of FA revealed differentially expressed genes were enriched for members of the ERK and NF-κB pathways. Subsequent in vitro analyses, utilizing isogenic RKO colon adenocarcinoma cells exposed to various doses of FA, demonstrated the downregulation of ERK and p-ERK in wild type (WT) p53+/+ cells, while an increase in expression was observed in p53−/− cells at the protein level. The goal of this study is to investigate the role of the MAPK/ERK pathway in the development of UC-associated neoplasms. An in vitro model that faithfully reproduces the inflamed microenvironment in the context of WT vs. mutant p53, the putative gatekeeper of UC-associated carcinogenesis, is needed to enhance our understanding of early changes in the colon that are induced by FA and drive tumor formation. Colon organoids are being generated by isolating crypts from WT p53+/+ and mutant p53+/515A mice. These organoids are then co-cultured with mouse macrophages (RAW264.7 cells) in inserts to stimulate crosstalk between the macrophages and colonic epithelial cells, as in the inflamed colon. Analyses demonstrate that the macrophages express pivotal inflammatory cytokines characteristic of UC, including IL-1β, IL-10, TNF-α, and IL-6, irrespective of the presence or absence of LPS stimulation. Co-cultured organoids and macrophages will be exposed to different concentrations of FA for various lengths of time, and the impact of treatment on the levels of ERK, p-ERK, and p65 will be assessed. The ability of p-ERK to mediate the transcriptional activation of NF-κB and its downstream effector IL-6 will also be evaluated. Subsequent investigations employing this innovative experimental model will reveal the mechanisms by which FA supplementation promotes the progression of UC-associated dysplasia. Given the potential risks associated with FA supplementation in individuals with UC, there is an urgent need to translate these results to a clinical setting. (Supported by CA262551 and the Timothy and Aurora Hughes Cancer Research Fund). Citation Format: Ariane Rocha Bartolomeu, Wen-Chi Chang, Lisa Vanderveer, Kristen N. Harvey, Mitchell Cheung, Harry S. Cooper, Margie Lee Clapper. Effects of folic acid supplementation on early stages of colitis-associated carcinogenesis [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 2170.