Disruption of the EGFR-SQSTM1 interaction by a stapled peptide suppresses lung cancer via activating autophagy and inhibiting EGFR signaling

Despite the success of epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) in the treatment of non-small cell lung cancer (NSCLC) harboring EGFR-activating mutations, intrinsic or acquired resistance remains the major obstacle to long-term disease remission. Defective autophagy has been reported as an EGFR-TKI resistance mechanism. However, how EGFR regulate autophagic flux are still not fully understood. Here we found that EGFR-stimulated phosphorylation of SQSTM1 at tyrosine 433 induces dimerization of its UBA domain, which disturbs the sequestration function of SQSTM1 and causes autophagic flux blocking. SAH-EJ2, a staple optimized EGFR-derived peptide, showed enhanced in vitro and in vivo antitumor activity against NSCLC than the prototype regardless of EGFR mutation status. Mechanistically, SAH-EJ2 disrupts the EGFR-SQSTM1 interaction and protects against EGFR-induced SQSTM1 phosphorylation, which hinders the dimerization of the SQSTM1 UBA domains and restores SQSTM1 cargo function. Moreover, SAH-EJ2 suppresses EGFR activity by blocking its dimerization and reducing its protein stability, which reciprocally activates the core autophagy machinery. Our observations reveal that disturbing the EGFR-SQSTM1 interaction by SAH-EJ2 confers a potential strategy in the treatment of NSCLC through suppressing EGFR signalling and activating autophagy simultaneously. •EGFR-SQSTM1 interaction triggers SQSTM1 phosphorylation at Y433, destroying the sequestration function of SQSTM1 in NSCLC.•Disturbing EGFR-SQSTM1 with a chimeric peptide PJMA1 rescues the cargo function of SQSTM1.•Staple-modified SAH-EJ2 shows improved physicochemical properties and antitumor activity against NSCLC than its prototype.•Blocking EGFR-SQSTM1 binding confers a potential therapeutic strategy against NSCLC via dual targeting EGFR and autophagy.