Physiologically relevant 3D CRISPR screening enhances mechanistic insight into chemical toxicity compared to 2D screening.

CRISPR-based approaches can complement other genomics-based toxicology studies by enabling causal interrogation of gene function modulating chemical-induced toxicity. Moreover, CRISPR screens enable scalable and systematic identification of functional pathways involved in cellular response to chemical exposure. Cell-based functional toxicogenomics approaches using CRISPR provide a potential powerful tool for the development of mechanism-driven new approach methodologies (NAMs) for toxicodynamic and toxicokinetic hazard screening to enable more effective risk assessment. To improve the physiological relevance of in vitro functional toxicogenomics, we developed a three-dimensional (3D) CRISPR screening platform using HepG2/C3A spheroids cultured in a continuously rotating bioreactor (ClinoStar). We evaluated the potential utility of a 3D CRISPR screen as compared to conventional 2D screen using a custom CRISPR sgRNA library representing common loss-of-function genetic variants in the human population and exposure to the well characterized DNA damaging toxicant, doxorubicin. The 3D platform identified more genes and pathways in which variants have previously been associated with doxorubicin toxicity in clinical studies than the 2D system. These results support the utility of 3D CRISPR screening to identify physiologically relevant genetic determinants underlying chemical toxicity.