(P22-047-25) Enhanced Dysplasia and Elevated Risk of Colitis-Associated Colorectal Cancer in hnRNPI Knockout (KO) Mice Following AOM/DSS Challenge

Objectives: Colitis-associated colorectal cancer (CAC) is a subtype of colon cancer arising from chronic inflammation in the colon. CAC develops through a multistep process, transitioning from inflammatory epithelium to dysplasia and eventually to malignancy. KOof the RNA-binding protein gene,hnRNPI, in epithelial cells in mice colon exacerbated inflammatory responses and led to the early onset of colitis. Single-cell RNA sequencing of hnRNPI KO mice colon demonstrated an increase in enteroendocrine cells compared to wild-type (WT) mice. We hypothesize that disrupted serotonin and related tryptophan metabolism in the hnRNPI KO mice leads to the progression of CAC.

Methods: 5-month-old WT (n=7) and KO (n=8) mice were challenged with azoxymethane/dextran sulfate sodium (AOM:15 mg/kgBW; DSS:1% in water). Body weight, fecal consistency, and fecal blood were monitored daily. After 8 weeks of the challenge, induction, and recovery procedure, mice were euthanized, and tissues were collected. Colon sections were analyzed for histological and pathological changes. Inflammatory markers, proliferation, and colitis were assessed. Fecal metabolites were analyzed using metabolomics.

Results: KO mice showed shorter colon lengths compared to WT. The number of lymphoid nodules was higher in KO mice and marked with increased CD45 intensity than in WT. The dysplasia index was increased in KO mice than in WT. Ki-67 marker was elevated in KO mice than in WT (33±7.2vs.15±3.5 Ki67⁺cells/area). β-catenin showed increased nuclear translocation in KO mice than in WT (11.4±3.2vs.4.7±2.0 β-catenin⁺cell number). The GATA3⁺cells in the lamina propria of KO mice were increased than in WT (8.3±0.9vs.3.6±0.6 GATA3⁺cells). KO mice showed increased serotonin⁺cells than WT (1.8±0.4vs.0.4±0.2 serotonin⁺cells/crypt). Fecal metabolomics revealed higher levels of indole-3-propionic acid and glycocholate and lower levels of tryptophan and indole lactic acid in KO mice.

Conclusions: hnRNPI KO mice have a significantly increased risk of developing CAC during AOM/DSS challenge and dysregulated fecal metabolites. These findings suggest further research to explore the mechanisms involving the metabolites during CAC progression.

Funding Sources: USDA Cooperative State Research, Education, & Extension Service; The Office of the Vice Chancellor for Research (UIUC)