Abstract 18: Transcriptomic analysis of mucinous adenocarcinoma in genetically-engineered mouse model

Abstract Background and Aim: The nature and characteristic of human mucinous colorectal adenocarcinomas have not been well elucidated yet. We previously reported a genetically-engineered mouse model for colonic neoplasia producing mucin based on inactivation of Transforming Growth Factor β Receptor Type II (Tgfbr2) and Apc (CDX2P-G19Cre;Apc flox/+;Tgfbr2flox/flox), which is useful to investigate the mechanism of tumor formation. This mouse model developed colonic neoplasia from 12 weeks of age. Despite the same genotype, 40% of the tumors were found mucinous adenocarcinoma and 28% were high-grade adenoma. For further investigation, we herein perform transcriptomic analysis to clarify the molecular differences in these two histologically different tumors. Method: Total RNA were extracted from mucinous adenocarcinomas and high-grade adenomas in CDX2P-G19Cre;Apcflox/+;Tgfbr2 flox/flox mice from fresh frozen tumors (n=3, each). Then, RNA-seq and Gene Set Enrichment Analysis were performed. Samples were sequenced on NovaSeq 6000, and gene sets queried included the Hallmark. Results: Mucinous adenocarcinoma and high-grade dysplasia were differentially clustered in principal component analysis despite the same genotype. Gene set enrichment analysis showed 19 upregulated signaling pathways including KRAS signaling and epithelial mesenchymal transition, and 8 suppressed signaling pathways including E2F targets and MYC targets in mucinous adenocarcinoma compared to high-grade dysplasia (FDR < 0.05). Conclusions: By comparing transcriptome of mucinous adenocarcinoma with high-grade adenoma in our mouse model, 27 differential signal pathways were detected. Some of these pathways are presumably associated with the nature and the characteristics of mucinous adenocarcinoma. We are further investigating the effects of these differences in signal pathways and the correlation with human mucinous adenocarcinoma. Citation Format: Haruki Sada, Hiroaki Niitsu, Hikaru Nakahara, Masashi Miguchi, Naoya Sakamoto, Naohide Oue, Hirotaka Tashiro, Hideki Ohdan, Takao Hinoi. Transcriptomic analysis of mucinous adenocarcinoma in genetically-engineered mouse model [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 18.