Dihydroartemisinin Mitigates Osimertinib Resistance in Lung Adenocarcinoma through Modulation of the EMT Transcription Factor Slug

Abstract

Background: Osimertinib, a third-generation tyrosine kinase inhibitor (TKI), is associated with a complex array of resistance pathways. Epithelial-mesenchymal transition (EMT) represents a mechanism contributing to resistance development in epidermal growth factor receptor (EGFR)-TKI treatment. Previous research suggests that the downregulation of Snail, a transcription factor linked to EMT, can delay the onset of osimertinib resistance. Slug, another member of the Snail family, remains underexplored in its impact on EMT-related osimertinib resistance. Dihydroartemisinin (DHA) has demonstrated efficacy in inhibiting the proliferation, invasion, and metastasis of various types of tumor cells, including lung cancer. This study confirmed that DHA could downregulate Slug expression and inhibit the metastasis and invasion of tumor cells. Methods: The cultured osimertinib-resistant lung adenocarcinoma cell line was named H1975/OE. Real-time polymerase chain reaction (RT-PCR), western blotting, and Transwell assays were employed to confirm EMT occurrence in H1975/OE cells. To investigate the mechanism of EMT in osimertinib resistance, we evaluated EMT-related markers in H1975 parental cells and H1975/OE-resistant cells. Complete silencing of the regulator Slug in H1975/OE cells using small interfering RNA (siRNA) was followed by an examination of alterations in the expression levels of EMT-associated markers. Finally, DHA, a natural inhibitor, was used to assess its interference with osimertinib resistance linked to EMT. Results: Evaluation of EMT-specific markers in the H1975 parental cell line and H1975/OE resistant cell line revealed upregulated N-cadherin expression and downregulated E-cadherin expression in H1975/OE cells. The enhanced invasiveness of H1975/OE indicated that EMT occurred in the resistant cell line. Subsequent experiments confirmed that Slug expression was upregulated in the resistant cell line and that knockout of Slug facilitated a delay in the occurrence of osimertinib resistance in H1975/OE cells. Further investigation demonstrated that DHA could inhibit Slug expression, alleviating osimertinib resistance associated with EMT. Conclusions: Slug plays a pivotal role in osimertinib resistance associated with EMT. DHA effectively overcomes osimertinib resistance linked to EMT by inhibiting Slug expression.