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LC3-associated phagocytosis of neutrophils trigger tumor ferroptotic cell death in glioblastoma

ABSTRACT: Necrosis is commonly found in various solid tumors and predicts worse outcome. Chronic ischemia can initiate tumor necrosis, but how the damaged tissue further expands is unclear. Previous studies found that neutrophils associate with necrosis and could contribute to necrosis development in glioblastoma (GBM) by transferring myeloperoxidase (MPO)-containing granules into tumor cells and inducing tumor cell ferroptosis. How the neutrophilic granule transfer occurs is unknown. Here, through an unbiased small molecule screen, we found that statins can inhibit neutrophil-induced tumor cell death by blocking the neutrophilic content transfer into tumor cells. Surprisingly, we found that neutrophils are engulfed by tumor cells before they are fragmented and release the MPO-containing contents in tumor cells. This process involves LC3-associated phagocytosis (LAP) and can be blocked by inhibiting the Vps34-UVRAG-containing PI3K complex. Inhibition of MPO or depletion of Vps34 in an orthotopic xenograft GBM mouse model reduced necrosis formation and allowed tumor-bearing mice to survive longer. Therefore, this study revealed that the neutrophilic granule transfer involves LAP-mediated neutrophil internalization, which then triggers tumor ferroptotic cell death in glioblastoma. Blocking this process may improve prognosis of GBM.

ORGANISM(S): Homo sapiens

PROVIDER: GSE263766 | GEO | 2024/04/29

REPOSITORIES: GEO

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Project description:Myeloperoxidase (MPO), an important diprotomeric glycoprotein in neutrophil-mediated immunity, produces microbicidal hypohalous acids, but the underpinning glycobiology remains elusive. Deep characterisation of neutrophil-derived MPO (nMPO) using advanced mass spectrometry demonstrated that under-processed oligomannosidic- and hyper-truncated paucimannosidic- and N-acetyl-β-D-glucosamine (GlcNAc) core-type asparagine-linked glycans decorate the protein. Occlusion of Asn355 and Asn391 and sterical hindrance of Asn323- and Asn483-glycans located in the MPO dimerisation zone were found to shape the local glycan processing thereby providing a molecular basis of the site-specific nMPO glycosylation. Native mass spectrometry, mass photometry, and glycopeptide profiling revealed extreme molecular complexity of diprotomeric nMPO arising from heterogeneous glycosylation, oxidation, chlorination and polypeptide truncation variants, and a lower-abundance monomer. Longitudinal profiling of maturing, mature, granule-separated, and pathogen-activated neutrophils demonstrated that MPO is dynamically expressed during granulopoiesis, unevenly distributed across granules and rapidly degranulated, but surprisingly carries uniform glycosylation across conditions. Complete proMPO-to-MPO maturation evidently occur during early/mid-stage granulopoiesis. The conserved Asn355- and Asn391-sequons displayed elevated GlcNAc signatures and higher oxidation and chlorination activity of the secretory vesicle/plasma membrane-resident MPO relative to MPO from other granules. Endoglycosidase H-treated nMPO displaying Asn355-/Asn391-GlcNAcylation recapitulated the activity gain and showed increased thermal stability and polypeptide accessibility relative to untreated nMPO as measured by activity assays, circular dichroism and molecular dynamics. Endoglycosidase H-treated nMPO also demonstrated elevated ceruloplasmin-mediated inhibition relative to nMPO. Modelling revealed that hyper-truncated Asn355-glycans positioned in the MPO:ceruloplasmin interface are critical for uninterrupted inhibition. We report on novel bimodal roles of the peculiar MPO glycosylation providing new insight into neutrophil glycobiology.

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LC3-associated phagocytosis of neutrophils trigger tumor ferroptotic cell death in glioblastoma

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