LPS-induced superoxide anion-dependent macrophage extracellular traps by store-operated calcium entry

Macrophage extracellular traps (METs) contribute to chronic inflammation in the tumor microenvironment, promoting cancer progression via necroptosis-induced extracellular matrix degradation. This study investigates the role of store-operated calcium entry (SOCE) in calcium-induced MET formation, a process that amplifies pro-tumorigenic inflammatory responses in macrophages. Mouse macrophage RAW264.7 and human monocyte U937 cells were stimulated with lipopolysaccharide (LPS) or phorbol myristate acetate (PMA), with or without pretreatment using Ca 2+ chelator BAPTA-AM, mechanical Ca 2+ channel inhibitor GdCl 3 , SOCE inhibitors SKF96365 or YM58483, or superoxide anion scavenger thymoquinone (TQ). METotic cells were identified via immunofluorescence staining for Lamin B after digitonin permeabilization. LPS and PMA triggered SOCE-mediated Ca 2+ influx, leading to elevated cytoplasmic Ca 2+ levels that activated NADPH oxidase (NOX) to produce superoxide anions, culminating in MET formation. Pharmacological inhibition of SOCE attenuated Ca 2+ influx and superoxide anion, whereas superoxide scavenging significantly inhibited METosis without altering NOX1/2 protein levels, indicating Ca 2+ -dependent NOX activation. These results reveal a SOCE-NOX-superoxide axis driving LPS-induced METosis, highlighting its potential in tumor progression. Targeting SOCE could disrupt macrophage-mediated inflammatory circuits in cancer initiation and progression