Abstract Background: Long interspersed nuclear element-1 (LINE-1; L1) retrotransposition is frequent in lung squamous cell carcinoma (LUSC), yet its functional impact remains largely unelucidated. We previously identified recurrent L1-ATP8B1 (L1 insertion in ATP8B1) associated with poor prognosis. Given ATP8B1’s role in lipid homeostasis, we hypothesize L1-ATP8B1 drives lipid metabolic reprogramming to promote LUSC progression. Methods: We integrated transcriptomic analyses of The Cancer Genome Atlas (TCGA) and validation cohorts with targeted metabolomics, functional assays, and tumor-immune cell co-culture systems. Mechanistic studies were conducted via genetic perturbation, pharmacologic inhibition, and rescue experiments in both in vitro and in vivo models. Results: Gene Ontology and KEGG enrichment analysis revealed L1-ATP8B1 correlated with deregulated lipid metabolism, particularly arachidonic acid (AA) metabolism. Metabolomic profiling results confirmed elevated AA-derived 5-HETE and 5-oxo-ETE (the oxidation metabolite of 5-HETE) in L1-ATP8B1-over-expressing cells. Mechanistically, L1-ATP8B1 up-regulated the transcriptional levels of PLA2G4 and ALOX5 to enhance AA release and 5-HETE generation. Pharmacologic inhibition of the activity of their metabolic enzymes cytosolic phospholipase A2 (cPLA2) and 5-lipoxygenase (5-LOX) abrogated tumor progression, whereas exogenous 5-oxo-ETE rescued the effects. Further, we found L1-ATP8B1 induced immune suppression by recruiting myeloid-derived suppressor cells (MDSCs). Co-culture experiments demonstrated 5-oxo-ETE enhanced the immunosuppressive function of MDSCs by activating non-canonical NF-κB signaling, thereby inhibiting T cell proliferation and IFN-γ production-an effect reversed by 5-LOX inhibition. Conclusions: Our findings uncover a previously unrecognized L1/cPLA2/5-LOX/NF-κB axis linking lipid metabolic reprogramming to LUSC immune evasion. L1-ATP8B1 drives tumor aggressiveness and immune suppression via lipid mediators. Targeting this pathway is a promising therapeutic strategy to overcome immune resistance in LUSC. Citation Format: Rui Zhang, Wenjing Tian, Pengpeng Liu, Jinpu Yu. LINE-1 retrotransposition drives lipid metabolic reprogramming and immune suppression in lung squamous cell carcinoma via cPLA2/5-LOX axis abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 4729.
Zhang et al. (Fri,) studied this question.