Oxymatrine Synergizes with 5-fluorouracil to Inhibit the Proliferation of A549 Cells by Targeting APE1

OBJECTIVE: Resistance to 5-fluorouracil (5-FU) necessitates its administration in combination with other drugs to enhance the clinical outcome. Oxymatrine (OMT) exhibits antitumor and anti-inflammatory activities. This study aimed to investigate the synergistic antitumor effect of OMT with 5-FU in A549 cells. METHODS: The knockout of human Apurinic/Apyrimidinic Endonuclease 1 (APE1) in A549 cells was achieved using shRNA. The level of APE1 protein was determined via Western blotting. The levels of IL-2, IL-6, and IL-8 were detected using ELISA. The level of intracellular Reactive Oxygen Species (ROS) and cell cycle were analyzed by flow cytometry. Genome-wide transcriptome profiling was conducted using RNA- sequencing technology and bioinformatics analyses. RESULTS: OMT synergistically augmented the antitumor activity of 5-FU in A549 cells by inhibiting the functions of APE1. OMT differentially modulated the secretion of IL-8, IL-6, and IL-2 from A549 cells in the presence of 5-FU. The inhibition of IL-8 and IL-6 by OMT predominantly occurred via APE1, whereas the inhibition of IL-2 by OMT was APE1-independent. OMT inhibited ROS production independent of APE1 and induced G2/M arrest in APE1-deficient cells. A genome-wide transcriptome analysis identified novel gene targets (B3GNT3, CRABP2, RHOV, and PCSK9) regulated by OMT, which contribute to its antitumor activity. DISCUSSION: These findings uncover a multitarget mechanism underlying the synergistic antitumor effect of OMT and 5-FU, confirming APE1 as a key regulatory factor linking inflammatory cytokine secretion, ROS homeostasis, and cell cycle progression in lung cancer cells. The newly identified target genes further elaborate the molecular basis of OMT-mediated tumor suppression. This work provides a potential strategy to overcome 5-FU resistance and optimize combination therapy for lung cancer treatment. CONCLUSION: This study addresses the issue of 5-FU chemoresistance in lung cancer by validating OMT as a functional synergistic adjuvant. The findings clarify the molecular mechanisms by which OMT enhances 5-FU antitumor efficacy, offering a credible experimental basis for the potential development of optimized combination therapeutic regimens for lung cancer.