Combined single-cell transcriptome and Mendelian randomization to identify and validate prognostic genes associated with endoplasmic reticulum stress and butyrate metabolism in lung adenocarcinoma

Background Lung adenocarcinoma (LUAD) is a prevalent and aggressive subtype of lung cancer, with a 5-year survival rate below 20% due to late-stage diagnosis and drug resistance. Endoplasmic reticulum stress (ERS) and butyrate metabolism (BM) play critical roles in tumor progression, but their co-regulatory features in LUAD remain unclear. Methods This study integrated single-cell transcriptome analysis and Mendelian randomization (MR) to identify prognostic genes associated with ERS and BM in LUAD. Public datasets were analyzed using weighted gene co-expression network analysis, differential expression analysis, and MR. A risk model and nomogram were constructed, and immune microenvironment, gene set enrichment, and single-cell analyses were performed to validate findings. Moreover, the expression of prognostic genes was validated in different Non-small cell lung cancer (NSCLC) cell lines through reverse transcription quantitative polymerase chain reaction (RT-qPCR). Results Seven prognostic genes ( VDAC1 , TXNRD1 , GDF15 , TRIB3 , LPL , KCNQ1 , PKP2 ) were identified, RT-qPCR assays confirmed that these genes exhibited significant expression differences in different NSCLC cell lines. The risk model demonstrated that low-risk patients had significantly better survival outcomes. The nomogram exhibited strong predictive accuracy for 1-, 3-, and 5-year survival. Enriched pathways in high-risk patients included olfactory transduction, while low-risk patients showed enrichment in ribosome and complement-coagulation cascades. Immune profiling revealed 13 differentially abundant immune cell types, including M1 macrophages. Single-cell analysis identified macrophages as key players in LUAD. Notably, VDAC1 , TXNRD1 , and LPL were highly expressed during early macrophage differentiation. Conclusion This study identifies seven ERS- and BM-related prognostic genes and highlights macrophages as pivotal in LUAD progression, the expression differences of candidate genes were verified by RT-qPCR assay. These findings provide novel insights into LUAD diagnosis, prognosis, and potential therapeutic targets, offering a foundation for precision medicine strategies. Further validation in clinical cohorts and functional studies is warranted to translate these discoveries into clinical applications.