Jaceosidin overcomes osimertinib resistance in lung cancer by inducing G2/M cycle arrest through targeting DDB1

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BACKGROUND: Osimertinib is a third-generation Epidermal Growth Factor Receptor (EGFR) tyrosine kinase inhibitor (TKI) widely used to treat advanced non-small cell lung cancer with EGFR mutations. However, resistance to osimertinib frequently develops, limiting its long-term effectiveness. PURPOSE: This study aimed to establish a lung cancer TKI-resistant model and identify Traditional Chinese Medicine (TCM) components that could reverse TKI resistance, enhancing lung cancer sensitivity to targeted therapies, while exploring the underlying molecular mechanisms. MATERIALS AND METHODS: Osimertinib-resistant cell lines and organoids were developed using a dose-escalation approach. A screen of 302 traditional Chinese medicine monomers revealed compounds that increased sensitivity to osimertinib. RNA sequencing and limited proteolysis coupled with small molecule mapping were employed to investigate the molecular mechanisms by which jaceosidin reverses resistance. The efficacy of the jaceosidin and osimertinib combination was confirmed in cell lines, organoids, and a mouse model. RESULTS: The osimertinib-resistant lung cancer model was successfully established, and 12 compounds were identified that enhanced the sensitivity of resistant cells to osimertinib. Among these, Jaceosidin, a flavonoid compound derived from Eupatorium lindleyanum DC., was confirmed to notably increase osimertinib sensitivity. Mechanistic studies, including limited proteolysis and RNA interference analysis, demonstrated that Jaceosidin directly interacts with Damage Specific DNA Binding Protein 1 (DDB1), promoting its protein expression and downregulating CDK1/Cyclin B1 levels. This interaction induced G2/M cell cycle arrest, thereby sensitizing lung cancer cells to osimertinib. Furthermore, both in vitro and in vivo experiments confirmed that the combination of Jaceosidin and osimertinib significantly inhibited tumor growth in osimertinib-resistant models. CONCLUSION: These findings offer new insights into the role of DDB1 in overcoming osimertinib resistance and suggest that combining jaceosidin with osimertinib may serve as a promising therapeutic strategy to enhance the efficacy of EGFR-TKIs treatment in resistant Non-small Cell Lung Cancer (NSCLC).

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