515P Multi-regional sequencing of oligometastatic non-small cell lung cancer patients reveals variations in clonal complexity

caspase site and the adjacent CBL-binding motif, thereby preventing generation of the pro-apoptotic p40MET fragment.Methods: METex14Del mutation was reconstituted CRISPR-Cas9 in a non-tumorigenic human bronchial epithelial cell line (16HBE).In parallel, cell lines harboring mutations affecting either the CBL site, the caspase site, or both sites were generated to decipher the respective contribution of these regulatory residues to the biological responses induced by METex14Del.MET-driven cellular responses were evaluated using real-time live-cell imaging (IncuCyte) for signaling, migration, invasion, cell scattering, and apoptosis.In vivo tumorigenesis was assessed in HGF-humanized NSG mice (NSG-huHGF), and transcriptomic profiling was performed via 3' RNA sequencing.Finally, an inducible p40MET METex14Del model was established to assess its impact on METex14Del-driven tumorigenesis.Results: METex14Del promotes sustained signaling, enhanced invasion, apoptosis resistance, and tumor growth in HGF-humanized mice.Genome editing revealed that combined -but not individual-mutations of the caspase and CBL sites phenocopy METex14Del.Moreover, inducible re-expression of p40MET in METex14Delexpressing cells restored apoptosis and suppressed tumor formation.Conclusions: Altogether, our findings identify MET exon 14 skipping as the first oncogenic mutation that drives tumorigenesis by abolishing the tumor-suppressive pro-apoptotic function of a dependence receptor, thereby redefining the oncogenic potential of MET.