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Functional genomics screening identifies aspartyl‐tRNA synthetase as a novel prognostic marker and a therapeutic target for gastric cancers

Efficient molecular targeting therapies for most gastric cancers (GCs) are currently lacking, despite GC being one of the most frequent and often devastating malignancies worldwide. Thus, identification of novel therapeutic targets for GC is in high demand. Recent advancements of high‐throughput nucleic acid synthesis methods combined with next‐generation sequencing (NGS) platforms have made it feasible to conduct functional genomics screening using large‐scale pooled lentiviral libraries aimed at discovering novel cancer therapeutic targets. In this study, we performed NGS‐based functional genomics screening for human GC cell lines using an originally constructed 6,399 shRNA library targeting all 2,096 human metabolism genes. Our screening identified aspartyl‐tRNA synthetase (DARS) as a possible candidate for a therapeutic target for GC. In‐house tissue microarrays containing 346 cases of GC combined with public datasets showed that patients with high expression levels of DARS protein exhibited more advanced clinicopathologic parameters and a worse prognosis, specifically among diffuse‐type GC patients. Both in vitro and in vivo experiments concretely evidenced that DARS inhibition achieved robust growth suppression of GC cells. Moreover, RNA sequencing of GC cell lines under shRNA‐mediated DARS knockdown suggested that DARS inhibition exerts its effect through the inactivation of multiple p‐ERK pathways. This MAPK‐related growth suppression by DARS inhibition would also be applicable to other cancers; thus, it is warranted to investigate the expression and clinical significance of DARS in a wide spectrum of malignancies. Taken together, NGS‐based high‐throughput pooled lentiviral screening showed DARS as a novel prognostic marker and a promising therapeutic target for GC. © 2022 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.