Genomic and cellular responses to aspirin treatment in colonic organoids from African- and European-Americans

Aspirin (ASA) is a proven chemoprotective agent for sporadic and hereditary colorectal cancer (CRC), though mechanisms underlying these effects are incompletely understood. Human-derived epithelial organoids are an ideal system to study host-environment interactions in the colon across individuals. Here, colonic organoids from a diverse cohort of African-Americans (AA) and European-Americans (EA) were used to profile genomic and cellular ASAresponses. Overall design: Human colonic organoids derived from 67 healthy individuals (33 AA and 34 EA) were cultured, differentiated and treated with 3mM ASA or vehicle control (DMSO) for 24 hours(h). Gene expression was measured using RNA-sequencing, and differentially responsive genes were analyzed by condition and population as well as for gene set enrichment. Top differentially responsive genes were assessed by time (3h, 6h & 24h) and dose (0.5mM and 3mM) using qPCR in independent organoid lines. eQTL mapping was performed to identify genetic variants associated with condition-specific responses. Proliferation, apoptosis and necrosis assays were performed in organoids, and apoptosis gene expression measured at several ASA doses and time points.