Identifying novel therapeutic targets in gastric cancer using genome-wide CRISPR-Cas9 screening.

Genome-scale CRISPR-Cas9 screening technology is a powerful tool to systematically identify genes essential for cancer cell survival. Herein, TKOv3, a genome-scale CRISPR-Cas9 knock-out library, was screened in the gastric cancer (GC) cells, and relevant validation experiments were performed. We obtained 854 essential genes for the AGS cell line, and 184 were novel essential genes. After knocking down essential genes: SPC25, DHX37, ABCE1, SNRPB, TOP3A, RUVBL1, CIT, TACC3 and MTBP, cell viability and proliferation were significantly decreased. Then, we analysed the detected essential genes at different time points and proved more characteristic genes might appear with the extension of selection. After progressive selection using a series of open datasets, 41 essential genes were identified as potential drug targets. Among them, methyltransferase 1 (METTL1) was over expressed in GC tissues. High METTL1 expression was associated with poor prognosis among 3 of 6 GC cohorts. Furthermore, GC cells growth was significantly inhibited after the down-regulation of METTL1 in vitro and in vivo. Function analysis revealed that METTL1 might play a role in the cell cycle through AKT/STAT3 pathways. In conclusion, compared with existing genome-scale screenings, we obtained 184 novel essential genes. Among them, METTL1 was validated as a potential therapeutic target of GC.