TY - JOUR T1 - Organoid cultures of early-onset colorectal cancers reveal distinct and rare genetic profiles JF - Gut JO - Gut SP - 2165 LP - 2179 DO - 10.1136/gutjnl-2019-320019 VL - 69 IS - 12 AU - Helen H N Yan AU - Hoi Cheong Siu AU - Siu Lun Ho AU - Sarah S K Yue AU - Yang Gao AU - Wai Yin Tsui AU - Dessy Chan AU - April S Chan AU - Jason W H Wong AU - Alice H Y Man AU - Bernard C H Lee AU - Annie S Y Chan AU - Anthony K W Chan AU - Ho Sang Hui AU - Arthur K L Cheung AU - Wai Lun Law AU - Oswens S H Lo AU - Siu Tsan Yuen AU - Hans Clevers AU - Suet Yi Leung Y1 - 2020/12/01 UR - http://gut.bmj.com/content/69/12/2165.abstract N2 - Objective Sporadic early-onset colorectal cancer (EOCRC) has bad prognosis, yet is poorly represented by cell line models. We examine the key mutational and transcriptomic alterations in an organoid biobank enriched in EOCRCs.Design We established paired cancer (n=32) and normal organoids (n=18) from 20 patients enriched in microsatellite-stable EOCRC. Exome and transcriptome analysis was performed.Results We observed a striking diversity of molecular phenotypes, including PTPRK-RSPO3 fusions. Transcriptionally, RSPO fusion organoids resembled normal colon organoids and were distinct from APC mutant organoids, with high BMP2 and low PTK7 expression. Single cell transcriptome analysis confirmed the similarity between RSPO fusion organoids and normal organoids, with a propensity for maturation on Wnt withdrawal, whereas the APC mutant organoids were locked in progenitor stages. CRISPR/Cas9 engineered mutation of APC in normal human colon organoids led to upregulation of PTK7 protein and suppression of BMP2, but less so with an engineered RNF43 mutation. The frequent co-occurrence of RSPO fusions with SMAD4 or BMPR1A mutation was confirmed in TCGA database searches. RNF43 mutation was found in organoid from a leukaemia survivor with a novel mutational signature; and organoids with POLE proofreading mutation displayed ultramutation. The cancer organoid genomes were stable over long culture periods, while normal human colon organoids tended to be subject to clonal dominance over time.Conclusions These organoid models enriched in EOCRCs with linked genomic data fill a gap in existing CRC models and reveal distinct genetic profiles and novel pathway cooperativity. ER -