Dong Gao

How intracellular proteins, normally hidden from the immune system, become targets of tumor-associated antibody responses remains unresolved, as does the function of such autoantibodies encoded by tumor-infiltrating B cells (TIL-Bs). Using monoclonal antibodies (mAbs) cloned from TIL-Bs in a spontaneous hepatocellular carcinoma (HCC) model, we define a class of antigens: secreted intracellular antigens (SICAs). Tumors co-opt upregulated autophagy to release cytosolic proteins, exemplified by ALDH1L1, through HSP90-mediated autophagy-dependent unconventional secretion. The resulting autoantibodies form immune complexes at the tumor site, where the SICA is locally available, recruiting and reprogramming neutrophils into tumor-associated neutrophils that drive tumor progression. Both neutrophil depletion and loss of Fcγ receptor binding abolish this effect. Autophagy-mediated SICA secretion and the corresponding autoantibody response are conserved in HCC patients and extend to lung, breast and cervical cancers. Tumors thus reshape their secretome to hijack humoral immunity, highlighting the SICA–autoantibody–FcγR axis as a potential therapeutic target.

Metastasis, responsible for > 90% of cancer-related mortality, represents the most lethal yet least mechanistically understood phase of cancer progression. A critical bottleneck is tumor cell migration through physically confined environments, including dense extracellular matrix, narrow capillaries and endothelial gaps. Although tumor cells reprogram their metabolism to facilitate cancer progression, it remains unclear how specific metabolic adaptations enable them to overcome the unique physical challenges posed by these confined spaces, thereby promoting distant metastasis. We conducted a CRISPR screen targeting 1685 metabolic enzymes and identified dihydrolipoamide dehydrogenase (DLD), a mitochondrial enzyme involved in energy metabolism, as essential for confined migration of tumor cells. Depletion or pharmacological inhibition of DLD suppressed CRC metastasis by impairing tumor cell migration through capillaries and endothelial gaps. Upon mechanical compression, heterogeneous nuclear ribonucleoprotein A0 (hnRNPA0) binds to the adenylate uridylate-rich element (ARE) in the 3′UTR of DLD, enhancing its mRNA stability and upregulating DLD expression in tumor cells during confined migration. Elevated DLD expression enhances tricarboxylic acid (TCA) cycle metabolism, increasing malate levels. Malate interacts with tubulin alpha-1B chain (TUBA1B) to promote microtubule assembly, facilitating confined migration and metastasis. Knock-in of an ARE-deleted DLD mutant (DLD ΔARE) or disruption of the malate–TUBA1B interaction significantly suppressed tumor metastasis. In CRC patients, DLD expression was upregulated in tumor cells within capillaries of primary tumors and correlated with metastatic recurrence. Our findings reveal that compressive forces drive metastatic dissemination by epigenetically reprogramming mitochondrial metabolism, which in turn fuels cytoskeletal remodeling.

The immunosuppressive tumor microenvironment remains a major obstacle to successful immunotherapy. Pathologically activated neutrophils, alternatively termed polymorphonuclear myeloid-derived suppressor cells (PMN-MDSCs), drive tumor immune evasion primarily by inducing CD8⁺ T cell tolerance. While direct intercellular contact between neutrophils and CD8⁺ T cells is essential for immunosuppressive activity, the mechanisms mediating this interaction need deeper understanding. We previously reported that CD300ld is required for recruiting PMN-MDSCs into tumors, suppressing T cell activation. Here we show that CD300ld mediates neutrophil-driven contact-dependent suppression of cytotoxic CD8⁺ T cells by binding to phosphatidylserine (PS). Mice with mutant CD300ld lacking PS-binding capacity exhibit reduced immunosuppressive activity. Blockade of the CD300ld-PS interaction by neutralizing antibodies demonstrates therapeutic efficacy against established tumors and synergizes with anti-PD1. Our findings establish CD300ld-PS-mediated cell contact as a critical mechanism of neutrophil-driven immune evasion, revealing a targetable checkpoint pathway to overcome tumor immune resistance and improve immunotherapy outcomes.

Prostate cancer resembles differentiated secretory luminal cells and shows cell-autonomous dependence on androgen receptor (AR) signaling, yet normal luminal cells are often considered dependent on paracrine stromal AR signaling. To resolve this, we conditionally deleted Ar in luminal acinar cells in vivo . Ar -deleted luminal cells persisted short-term, in contrast to the rapid regression observed after castration, but were impaired in regeneration and progressively lost. Their depletion was accompanied by replacement through basal-to-luminal differentiation of AR intact basal cells. Transcriptomic and chromatin profiling showed cell-autonomous suppression of the secretory program with induction of stemness, inflammatory, and epithelial-to-mesenchymal transition signatures after AR loss. Mechanistically, the MAP kinase pathway and downstream AP-1 transcription factors were activated and functionally validated, and MAP kinase inhibition selectively depleted AR-deleted luminal cells, indicating a compensatory survival pathway. These findings define intrinsic roles for luminal AR in maintaining differentiation, restraining plasticity, and sustaining regeneration and homeostatic turnover, providing a mechanistic basis for AR dependence in prostate cancer.

Mutations in the extracellular or intracellular domains of epidermal growth factor receptor (EGFR) are implicated in the development of various cancers. While the intracellular mutations of EGFR have been extensively studied, the function of extracellular mutations remains poorly understood. In this study, we identify an EGFR mutant (EGFR R252C) in a patient with multifocal lung cancer and glioma, in which arginine (R) 252 is mutated to cysteine (C) in the EGFR extracellular domain. This mutation promotes C252-C252 disulfide-mediated EGFR dimerization and induces a conformational change of EGFR, leading to absent autophosphorylation and enhanced direct interaction between EGFR and extracellular signal-regulated protein kinase 1/2 (ERK1/2). Importantly, EGFR directly phosphorylates ERK1/2 at threonine (T) 202 / tyrosine (Y) 204 and activates ERK1/2, thereby promoting tumor cell proliferation and tumor growth in vivo. Afatinib, a second-generation EGFR tyrosine kinase inhibitor, effectively suppresses primary tumor growth and extends progression-free survival in the patient with multifocal lung cancer and glioma driven by EGFR R252C. Our finding elucidates the activation mechanism of this extracellular EGFR mutation and demonstrates the efficacy of afatinib in treating lung cancer or glioma patients with this variant.

Metastasis remains the primary cause of cancer-related mortality. During dissemination, cancer cells must navigate spatially confined microenvironments, yet the underlying metabolic adaptations that facilitate this process remain unclear. Here, through an in vivo CRISPR screen targeting metabolic enzymes, we identify aldehyde dehydrogenase 1 family member B1 (ALDH1B1) as essential for tumor cell survival in confining capillaries. Mechanistically, compressive force induces casein kinase 2 alpha 3 (CSK23) to phosphorylate kappa-B kinase subunit beta (IKKβ) at Ser177/181, which activates the nuclear factor kappa B (NF-κB) pathway and upregulates ALDH1B1. The upregulation of ALDH1B1 enhances aldehyde detoxification, which suppresses ferroptosis and promotes tumor cell survival during migration through the capillaries, thereby facilitating metastasis. Importantly, genetic or pharmacological inhibition of CSK23 or ALDH1B1 effectively impairs metastasis. In lung cancer patients, confined tumor cells exhibit higher levels of ALDH1B1 and NF-κB activation, which correlates with metastatic recurrence. Our findings reveal a mechano-metabolic pathway that promotes metastasis and suggest CSK23 and ALDH1B1 as potential therapeutic targets.