Abstract 260: PDCD10 regulates Wnt activation-induced intestinal adenoma formation by promoting Wnt dependent stem cell function

Abstract The goal of this study is to understand how PDCD10 regulates early steps of tumor development by using genetically modified mice and organoids. BACKGROUND: Programmed cell death 10 (PDCD10) is an adaptor protein critical for vascular development. Germline loss of function mutations of PDCD10 cause familial cerebral cavernous malformation. While some studies show that upregulated PDCD10 increases cancer aggressiveness, others show that the loss of PDCD10 promotes tumor progression. Given these conflicting reports, the role PDCD10 plays in tumorigenesis and cancer aggressiveness remains largely elusive. Furthermore, as most of the previous studies were performed using established 2D adapted tumor cell lines, how PDCD10 affects the early stages of tumorigenesis has not yet been investigated. In this study, we aimed to delineate how PDCD10 expression affects early stage of tumor development in the intestine using genetically modified mice. METHODS: Intestinal stem cell (ISC) and intestinal epithelial cell (IEC) specific Pdcd10 deletion mice were generated by crossing Olfm4-EGFP-CreERT2 and Vil-CreERT2 mice with Pdcd10floxed mice, respectively. Ctnnb1 (β-catenin encoding gene) exon 3 floxed mice were crossed with these mice to induce Wnt activation. IEC organoids from these mice were generated and characterized. Histological and molecular analyses were performed using samples obtained from mice and organoids. RESULTS: Tamoxifen-induced Wnt activation in Olfm4-EGFP-CreERT2 Ctnnb1 exon 3 floxed mice caused progressive weight loss, leading to animal death. These changes were limited by Pdcd10 deletion. Histological assessment revealed that while Wnt activation induced significant adenoma formation, particularly in proximal small intestine, very limited adenoma was present in Wnt activated mice with Pdcd10 deletion in ISCs. Lineage tracing studies using mice with tamoxifen-induced IEC specific Pdcd10 deletion showed that Pdcd10 deletion reduced ISC function. This ISC defect was associated with reduced expression of intestinal stem cell markers, including Lgr5, Olfm4, and Lrig1, along with decreased expression of Axin2 and other Wnt signaling marker genes. Studies using IEC organoids derived from Pdcd10 floxed mice indicated that 4-hydroxytamoxifen-induced Pdcd10 deletion limited organoid growth, and reduced ISC marker and Wnt signaling marker gene expression. Induced Wnt activation in organoids by CHIR99021 rescued Pdcd10 deletion-induced organoid growth defect, and lineage tracing studies showed that Ctnnb1 exon 3 deletion reverses ISC defects in Pdcd10 deleted mice. CONCLUSION: PDCD10 is required for optimal Wnt signaling to maintain ISC function and participates in Wnt-induced intestinal adenoma formation. These results demonstrate that targeting PDCD10 function and related signaling pathways may serve as therapeutic targets to limit cancer progression. Citation Format: Trisha Mondal, Sneha Kesaraju, Li Dong, Alex Ellerstein, Tong-Chuan He, Evgeny Izumchenko, Christopher R. Weber, Le Shen. PDCD10 regulates Wnt activation-induced intestinal adenoma formation by promoting Wnt dependent stem cell function [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 260.