Apurinic/Apyrimidinic Endonuclease 1/Reduction-Oxidation Effector Factor-1 (Ape1) Regulates The Expression Of Nlr Family Pyrin Domain Containing 3 (Nlrp3) Inflammasome Through Modulating Transcription Factor Nf-Kappa B And Promoting The Secretion Of Inflammatory Mediators In Macrophages

Background: Inflammatory mediators play an important role in the occurrence, development, and metastasis of tumors. The aim of the present study was to elucidate the effect of apurinic/apyrimidinic endonuclease 1/reduction-oxidation effector factor-1 (APE1) on inflammatory mediator secretion, which is dependent on the APE1-mediated NLR family pyrin domain containing 3 (NLRP3) regulatory mechanism.Methods: The human myeloid leukemia mononuclear cell line (THP-1) cells were cultured and polarized to M2 subset macrophages. Enzyme-linked immunosorbent assay was used for determining tumor necrosis factor-alpha (TNF-alpha), interleukin (IL)-1 beta, IL-18, IL-10, and IL-33 levels. Reverse transcription-polymerase chain reaction and western blot were used for evaluating TNF-alpha, NLR family pyrin domain containing 1 (NLRP1), NLRP3, caspase-1, and apoptosis-associated speck-like protein containing a card expression. Plasmid silencing APE1 gene (APE1(shRNA)) was synthesized and packaged into lentiviral. For activating inflammasomes, M2-type THP-1 cells were transfected with lentiviral vector APE1(shRNA) incubated with lipopolysaccharide (LPS) (100 ng/mL)/APE1 inhibitor (E3330, 20 mu M) and ATP. Electrophoretic mobility shift assay and dual-luciferase reporter assay were used for determining the interaction between NLRP3 and nuclear factor-kappa B (NF-kappa B) molecule.Results: APE1 significantly induced LPS-induced pro-inflammatory cytokine production, including TNF-alpha, IL-1 beta, and IL18, compared with THP-1 cells without APE1 treatment (P<0.05). APE1 promoted LPS-induced NLRP3 inflammasome activation by modulating the gene transcription of NLRP3-associated molecules. APE1 enhanced LPS-induced NLRP3 inflammasome activation by regulating NLRP3 and caspase-1 protein expression. APE1 improved NLRP3 activity by modulating the interaction between NLRP3 and NF-kappa B, and the modulation of NF-kappa B. APE1 promoted LPS-induced NLRP3 inflammasome activation through an NF-kappa B-dependent pathway.Conclusions: APE1 regulates the expression of NLRP3 by modulating transcription factor NF-kappa B and further promoting the secretion of inflammatory mediators IL-1 beta and IL-18 in macrophages. The findings of the present study provide theoretical and experimental bases for the design of tumor-associated macrophage (TAM)-targeted therapy, with APE1 as the target molecule.