1259 - Multi-Omics Analysis of Choline Metabolism Reprogramming and Neutrophil Chemotaxis in Host Responses to Radiation-Responsive Micrococcus luteus in NSCLC

Purpose/Objective(s): Radiotherapy remains a key treatment for non-small cell lung cancer (NSCLC) and can remodel the tumor microenvironment (TME). The response of intratumoral microbiota to radiation and subsequent influence on tumor behavior is not well understood. Here, we aimed to identify microbial taxa that are modulated by X-ray irradiation and to investigate their functional significance and mechanistic pathways in NSCLC progression.

Materials/Methods: 16S rDNA sequencing was employed to compare the microbial composition of irradiated versus non-irradiated NSCLC samples, leading to the identification of Micrococcus luteus (M. luteus) as a radiation-responsive bacterium. The biological effects of M. luteus on NSCLC cells were evaluated using migration, invasion, and radioresistance assays in vitro, and its tumor-promoting role was confirmed in xenograft models. Integrated multi-omics approaches, encompassing transcriptomic, proteomic, and metabolomic profiling, were applied to uncover the molecular networks altered by M. luteus.

Results: Irradiation resulted in a marked enrichment of M. luteus, which in turn enhanced the migratory, invasive, and radioresistant capacities of NSCLC cells. Multi-omics integration revealed that M. luteus triggers a coordinated upregulation of immune-related pathways, particularly those governing neutrophil chemotaxis, with significant induction of ras-related C3 botulinum toxin substrate 2 (RAC2) and C-X-C motif chemokine ligand 8 (CXCL8). These transcriptional changes correlated with increased neutrophil infiltration and elevated RAC2 protein levels in tumor tissues. Metabolomic analysis further demonstrated perturbations in choline metabolism, indicating a global metabolic reprogramming in response to M. luteus colonization.

Conclusion: Our findings reveal a reciprocal interaction between radiotherapy and the intratumoral microbiota: X-ray exposure selectively enriches M. luteus, which subsequently fuels NSCLC progression through the RAC2/CXCL8 axis and a metabolic rewiring of phosphatidylcholine pathways, ultimately promoting neutrophil recruitment. Disrupting this microbiota-driven circuit presents a novel strategy to augment radiotherapy efficacy in NSCLC.