Abstract
Background: Non-small cell lung cancer (NSCLC), particularly lung adenocarcinoma (LUAD), is a leading cause of cancer-related mortality. Osimertinib, a third-generation epidermal growth factor receptor-tyrosine kinase inhibitor (EGFR-TKI), improves survival, but acquired resistance remains a major clinical challenge. Methods: Transcriptomic profiles of osimertinib-sensitive and -resistant EGFR-mutant cell lines were analyzed to identify resistance mechanisms. Resistance-associated genes were used to develop a Cox proportional hazards (CoxPH) prognostic model based on The Cancer Genome Atlas (TCGA) data. Immune context and tumor mutational burden (TMB) were compared between risk groups. Core gene expression was validated by reverse transcription quantitative polymerase chain reaction (RT‒qPCR). Functional experiments including Cell Counting Kit-8 (CCK8) and methylthiazolyldiphenyl-tetrazolium bromide (MTT) assays were performed to evaluate the impact of core gene on the proliferative capacities of EGFR-TKI resistance cells. Results: Resistant cells showed gene expression alterations enriched in proliferation (e.g., Wnt) and cell cycle pathways. An 18-gene signature strongly predicted overall survival (concordance index [C-index] = 0.74). High-risk patients exhibited more immunosuppressive microenvironments and higher TMB. Nine genes (GLI2, LHX2, PITX3, MSX1, ANO1, MUC5B, BEST4, SLC46A3, ECEL1P2) were independent prognostic factors, and LHX2 occupied a central position. LHX2 was upregulated in resistant cells, and its knockdown restored osimertinib sensitivity. Conclusion: This study reveals novel genes and mechanisms in osimertinib resistance. The prognostic model stratifies LUAD patients effectively, and LHX2 represents a promising therapeutic target for reversing resistance.