Genome-wide CRISPR/Cas9 screening for therapeutic targets in NSCLC carrying wild-type TP53 and receptor tyrosine kinase genes

Background Targeted drugs have greatly improved the therapeutic outcome of non-small cell lung cancer (NSCLC) patients compared with conventional chemotherapy, whereas about one-third of patients are so far not suitable for targeted therapy due to lack of known driver oncogenes such as a mutated receptor tyrosine kinase (RTK) genes. In this study, we aimed to identify therapeutic targets for this subgroup of NSCLC patients. Methods We performed genome-wide CRISPR/Cas9 screens in two NSCLC cell lines carrying wild-type TP53 and receptor tyrosine kinase (wtTP53-RTK) genes using a GeCKO v2.0 lentiviral library (containing 123411 sgRNAs and targeting 19050 genes). MAGeCKFlute was used to analyse and identify candidate genes. Genetic perturbation and pharmacological inhibition were used to validate the result in vitro and in vivo. Results The Genome-wide CRISPR/Cas9 screening identified MDM2 as a potential therapeutic target for wtTP53-RTK NSCLC. Genetic and pharmacological inhibition of MDM2 reduced cell proliferation and impaired tumour growth in the xenograft model, thus confirming the finding of the CRISPR/Cas9 screening. Moreover, treatment by a selective MDM2 inhibitor RG7388 triggered both cell cycle arrest and apoptosis in several NSCLC cell lines. Additionally, RG7388 and pemetrexed synergistically blocked the cell proliferation and growth of wtTP53-RTK tumours but had limited effects for other genotypes. Conclusions We identified MDM2 as an essential gene and a potential therapeutic target in wtTP53-RTK NSCLC via a genome-wide CRISPR/Cas9 screening. For this subgroup, treatment by RG7388 alone or by its combination with pemetrexed resulted in significant tumour inhibition.