Abstract 3712: Proliferative and invasive colorectal tumors in pet dogs provide unique insights into human colorectal cancer

Abstract

Abstract Spontaneous tumors in pet dogs represent a valuable but undercharacterized cancer model. To better use this resource, we performed an initial global comparison between proliferative and invasive colorectal tumors from 20 canine cases and evaluated their molecular homology to human colorectal cancer (CRC). We sequenced 15 canine intestinal samples for WGS and 26 for RNA-seq. We investigated alterations in the genome and transcriptome, using state-of-the-art analysis tools. We aslso investigated their microbiome, by mapping WGS and RNA-seq read pairs that could not be placed onto the canine genome to two microbial genome databases: The Human Microbiome Project database and all bacterial genomic sequences. We performed the same analysis with TCGA (The Cancer Genome Atlas) colon cancer data. Based on our analysis, proliferative canine tumors harbor overactivated WNT/β-catenin pathways and recurrent CTNNB1 (β-catenin) mutations S45F/P, D32Y and G34E. Invasive canine tumors harbor prominent fibroblast proliferation and overactivated stroma. Both groups have recurrent TP53 mutations. We observed three invasion patterns in canine tumors: collective, crypt-like and epithelial-mesenchymal transition (EMT). We detected enriched Helicobacter bilis and Alistipes finegoldii in proliferative and crypt-like tumors, but depleted mucosa-microbes in the EMT tumor. Additionally, guided by our canine findings, we classified 79% of 478 human colon cancers from TCGA into four subtypes: primarily proliferative, or with collective, crypt-like or EMT invasion features. Their molecular characteristics match those of canine tumors. We showed that consensus molecular subtype 4 (mesenchymal) of human CRC should be further divided into EMT and crypt-like subtypes, which differ in TGF-β activation and mucosa-microbe content. Our canine tumors share the same pathogenic pathway as human CRCs. Dog-human integration identifies three CRC invasion patterns and improves CRC subtyping. Citation Format: Jin Wang, Tianfang Wang, Yanfang Sun, Yuan Feng, William C. Kisseberth, Carolyn J. Henry, Irene Mok, Susan E. Lana, Kevin Dobbin, Nicole Northrup, Elizabeth W. Howerth, Shaying Zhao, Houjian Cai. Proliferative and invasive colorectal tumors in pet dogs provide unique insights into human colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3712.