Cucurbitacin B regulates the resistance of osimertinib by inhibiting cell migration and invasion in non-small cell lung cancer

Non-small cell lung cancer (NSCLC) is the primary pathological type of lung cancer. Osimertinib, as a third-generation EGFR-TKI (epidermal growth factor receptor-tyrosine kinase inhibitor) targeted drug, effectively prolong the progression-free survival of patients with EGFR-mutated NSCLC. However, drug resistance limits the efficacy of osimertinib. Traditional Chinese medicine can effectively delay the resistance to EGFR-TKIs. In this study, Cucurbitacin B (CuB) was investigated to analyze its pharmacological effects in osimertinib-resistant NSCLC cells through cell viability, migration, and invasion experiments. Public databases were used to screen potential targets of CuB in osimertinib-resistant NSCLC cells, and the interactions between CuB and potential targets were verified through molecular docking, cellular thermal shift assay (CETSA), and microscale thermophoresis (MST). Western blot was used to detect the effects of CuB on downstream pathways of the targets. The results showed that CuB significantly reduced the proliferation activity of osimertinib-resistant NSCLC cells and inhibited the migration and invasion abilities of tumor cells. Mechanistically, CuB inhibited the expression of ERK and AKT molecules by binding to the tyrosine kinase receptor AXL. In summary, CuB exhibits resistance to osimertinib-resistant NSCLC by inhibiting the migration and invasion of resistant cells through regulating the abnormal activation of the AXL-ERK/AKT axis. This study provides a basis for the pre-clinical in vitro efficacy of CuB in the treatment of osimertinib targeted resistance in NSCLC and theoretical support for the development of clinical drug combinations.