The natural product berberine synergizes with osimertinib preferentially against MET-amplified osimertinib-resistant lung cancer via MET inhibition

Background: and Purpose: Berberine is a natural antimicrobial, anti-inflammatory product used in traditional Chinese medicine. Osimertinib is the first third-generation EGFR-tyrosine kinase inhibitor (TKI) approved for non-small cell lung cancer (NSCLC) with activating EGFR mutations and those resistant to earlier generation EGFR-TKIs. However, emergence of acquired resistance limits its long-term efficacy. One known mechanism of acquired resistance to EGFR-TKIs is MET (c-MET) gene amplification. This study has demonstrated berberine’s potential in overcoming acquired resistance to osimertinib. Experimental Approach: Drug effects in vitro were evaluated through cell counts, colony formation, apoptosis and protein degradation assays, and gene overexpression/knockouts. In vivo drug effects were measured with mouse xenograft models. Berberine’s interactions with MET were determined via molecular docking analysis and protein kinase assays. Key Results: Berberine combined with osimertinib synergistically and selectively decreased the survival of several MET-amplified osimertinib-resistant EGFR mutant NSCLC cell lines with enhanced induction of apoptosis, likely through Bim elevation and Mcl-1 reduction. Importantly, this combination effectively suppressed the growth of MET-amplified osimertinib-resistant xenografts in nude mice and was well tolerated. Molecular modeling showed that berberine could bind to the kinase domain of non-phosphorylated MET, occupy the front of the binding pocket, and interact with the activation loop, similar to other known MET inhibitors. The MET kinase assay clearly showed berberine’s concentration-dependent inhibition of MET activity. Conclusions and Implications: These findings collectively suggest that berberine can act as a naturally-existing MET inhibitor to synergize with osimertinib in overcoming osimertinib acquired resistance caused by MET amplification.