Abstract

Lung adenocarcinoma (LUAD) is an exceptionally aggressive malignancy characterized by high mortality rates. Neutrophils fulfill dual roles in cancer, demonstrating the capacity to both inhibit and facilitate tumor development. This study aimed to delineate the functional contributions and mechanistic underpinnings of Homo sapiens circular RNA 0000376 (hsa_circ_0000376) in LUAD progression and neutrophil polarization. Quantitative real-time polymerase chain reaction (RT-qPCR) was utilized to determine the expression levels of hsa_circ_0000376 in LUAD clinical specimens and established cell lines. A comprehensive set of experimental techniques was applied to evaluate its influence on LUAD cellular phenotypes: the Cell Counting Kit-8 (CCK-8) assay for assessing proliferation, colony formation assay for clonogenic potential, flow cytometry for detecting apoptosis, the scratch wound assay for evaluating migration, and the Transwell assay for quantifying invasive capacity. Flow cytometric analysis was additionally employed to measure neutrophil polarization towards the N1 (inducible nitric oxide synthase [iNOS] + /CD16b + ) and N2 (Arginase-1 [Arg1] + /CD16b + ) subtypes. Bioinformatics analyses combined with RNA immunoprecipitation (RIP) assays were performed to validate molecular interactions involving insulin-like growth factor 2 mRNA-binding protein 3 (IGF2BP3), hsa_circ_0000376, and solute carrier family 2 member 1 (SLC2A1). The expression of hsa_circ_0000376 was found to be significantly upregulated in both LUAD tissues and cultured cell lines. Genetic silencing of hsa_circ_0000376 effectively impeded cellular proliferation, migration, and invasion while simultaneously promoting apoptotic cell death in LUAD cells. Moreover, conditioned medium collected from hsa_circ_0000376-depleted LUAD cells stimulated a shift towards N1 polarization and concurrently restrained N2 polarization in treated neutrophils. Mechanistically, hsa_circ_0000376 was demonstrated to physicall