Integrin-targeting cyclic peptides suppress TGF-β1-driven EMT and invasion in third-generation EGFR-TKI-resistant NSCLC.

Resistance to third-generation EGFR-TKIs such as naquotinib and osimertinib remains a major obstacle in the treatment of non-small cell lung cancer (NSCLC). Epithelial-mesenchymal transition (EMT) is a key mechanism driving drug resistance and metastatic progression. Cilengitide, a cyclic RGD peptide targeting integrins, has shown potential in suppressing EMT-associated signaling. This study examined the effects of cilengitide and its derivatives on TGF-β1-induced EMT, migration, and invasion in EGFR-TKI-resistant NSCLC cells. Naquotinib- and osimertinib-resistant HCC827 cell lines were established and analyzed using 2D and 3D culture models. EMT marker expression, cell viability, migration, and invasion were assessed following treatment with cilengitide derivatives (R-1, R-7, R-8). Combination treatment with dovitinib, an FGFR inhibitor, was also evaluated. Experimental approaches included qRT-PCR, western blotting, wound-healing assays, invasion assays, and whole-mount organoid staining. Resistant cells exhibited reduced epithelial markers and increased mesenchymal markers, along with enhanced migration and invasion upon TGF-β1 stimulation. Cilengitide and its derivatives significantly inhibited TGF-β1-induced EMT, migration, and invasion, with stronger effects observed in 3D organoid models. Among the derivatives, cilengitide (R-8) most effectively suppressed vimentin expression and ERK1/2 phosphorylation. Combination treatment with dovitinib further enhanced the inhibition of migration and invasion, suggesting synergistic potential.