CRISPR library knockout screening identified candidate genes whose loss of function confers lapatinib resistance in HER2-amplified GC cells.

To identify genes, whose loss of function confers drug resistance to lapatinib, we performed a genome-wide CRISPR/Cas9 gene knockout screening in two human gastric cancer cell lines harboring HER2 amplification, N87 and OE19, respectively. By performing this study, we identiied a goup of genes associated with lapatinib resistance in HER2-amplified gastric cancer. A pooled GeCKO V2 library were amplified for lentivirus production, and then two biological replicates of N87 and OE19 cells were transduced with the lentivirus containing GeCKO V2 library at a multiplicity of infection (MOI) of 0.3. Puromycin selection was performed before lapatinib treatment on each cell line to enrich successfully transduced cells. After 14 days of lapatinib treatment, the drug-treated and vehicle-treated cells were harvested. Genomic DNA was extracted for PCR amplification and subsequent deep sequencing of the regions containing the sgRNAs.