Yanfeng Liu

Hepatocellular carcinoma (HCC) driven by gain-of-function mutations in CTNNB1 (CTNNB1GOF) that stabilize β-catenin exhibits a profoundly immunosuppressive tumor microenvironment (TME), rendering it resistant to immune checkpoint blockade (ICB). Metabolic reprogramming is increasingly recognized as a crucial mediator of immune activity, highlighting the need to elucidate the specific metabolic mechanisms underlying immune exclusion in CTNNB1GOF HCC. In this study, we identified a critical metabolic–immune network orchestrated by comutations of CTNNB1 and ARID2. Integrative analysis of cohorts of patients with HCC and a de novo MYC/CTNNB1GOF HCC mouse model revealed that tumors harboring concurrent CTNNB1 and ARID2 mutations exhibited a more immune-active TME and improved survival compared with tumors with CTNNB1 mutations alone. Mechanistically, β-catenin and ARID2 cooperatively enhanced the transcription of tryptophan 2,3-dioxygenase (TDO2), leading to accelerated kynurenine production and activation of the aryl hydrocarbon receptor (AhR) in myeloid-derived suppressor cells (MDSC). This metabolic axis established an immunosuppressive milieu characterized by MDSC accumulation and impaired T-cell function. Genetic ablation of Arid2 in CTNNB1GOF HCC attenuated TDO2-dependent kynurenine synthesis, reduced MDSC infiltration, and enhanced CD8+ T-cell cytotoxicity, thereby sensitizing tumors to anti–PD-1 therapy. Clinically, comutations of CTNNB1 and ARID2 correlated with elevated immune infiltration and favorable ICB responses across multiple human cancers, including HCC. Importantly, pharmacologic inhibition of AhR phenocopied the immunomodulatory effect of ARID2 loss and, when combined with anti–PD-1, robustly reversed the immune-cold phenotype of CTNNB1GOF HCC. These findings reveal TDO2–kynurenine–AhR signaling as a pivotal metabolic pathway enforcing immune evasion in CTNNB1-mutant HCC. Significance: β-catenin and ARID2 cooperatively orchestrate a metabolic immunosuppressive program in hepatocellular carcinoma by driving kynurenine production and AhR activation, identifying AhR inhibition as a promising therapeutic strategy to enhance immunotherapy efficacy.

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.

The immune evasion is one major challenge for cancer immunotherapy. Despite considerable advancements in immune checkpoint blockade (ICB) therapies for the advanced non‐small cell lung cancer (NSCLC) patients, only a minority of patients receive long‐term survival benefit. Here, this work demonstrates that lysine methyltransferase 5C (KMT5C) is a crucial promoter of the NSCLC progression and immune evasion. This work first observes that upregulation of KMT5C in NSCLC correlated with cancer progression and poor patient prognosis. Notably, KMT5C knockdown in NSCLC cells suppress tumor growth and metastasis in mice. Mechanistically, this work demonstrates that KMT5C activated the DNA repair response to inhibit the STING‐IRF3 pathway, downstream type I IFN signaling, and CCL5 secretion, leading to the downregulation of CD8⁺ T cell infiltration and function in NSCLC, ultimately facilitating tumor immune evasion and tumor progression. Importantly, both the pharmacological inhibitor A196 and the genetic inhibition of KMT5C could synergize with anti‐PD‐1 therapy in the lung cancer mouse model. Clinically, high expression levels of KMT5C in patients with NSCLC are associated with a lower response rate and worse clinical outcomes to ICB therapy. Therefore, these findings identify a previously unknown functional link between KMT5C and tumor immune evasion, and demonstrate that targeting KMT5C may be a potential therapeutic approach for enhancing the efficacy of NSCLC patients to ICB therapy.

Diverse post-translational modifications have been shown to play important roles in regulating protein function in eukaryotes. By contrast, the roles of post-translational modifications in bacteria are not so well understood, particularly as they relate to pathogenesis. Here, we demonstrate post-translational protein modification by covalent addition of lactate to lysine residues (lactylation) in the human pathogen Staphylococcus aureus. Lactylation is dependent on lactate concentration and specifically affects alpha-toxin, in which a single lactylated lysine is required for full activity and virulence in infection models. Given that lactate levels typically increase during infection, our results suggest that the pathogen can use protein lactylation as a mechanism to increase toxin-mediated virulence during infection.

Background and aims: The immunosuppressive tumor microenvironment (TME) plays an essential role in cancer progression and immunotherapy response. Despite the considerable advancements in cancer immunotherapy, the limited response to immune checkpoint blockade (ICB) therapies in patients with hepatocellular carcinoma (HCC) remains a major challenge for its clinical implications. Here, we investigated the molecular basis of the protein O-fucosyltransferase 1 (POFUT1) that drives HCC immune evasion and explored a potential therapeutic strategy for enhancing ICB efficacy. Methods: De novo MYC/Trp53^−/− liver tumor and the xenograft tumor models were used to evaluate the function of POFUT1 in immune evasion. Biochemical assays were performed to elucidate the underlying mechanism of POFUT1-mediated immune evasion. Results: We identified POFUT1 as a crucial promoter of immune evasion in liver cancer. Notably, POFUT1 promoted HCC progression and inhibited T-cell infiltration in the xenograft tumor and de novo MYC/Trp53^−/− mouse liver tumor models. Mechanistically, we demonstrated that POFUT1 stabilized programmed death ligand 1 (PD-L1) protein by preventing tripartite motif containing 21-mediated PD-L1 ubiquitination and degradation independently of its protein-O-fucosyltransferase activity. In addition, we further demonstrated that PD-L1 was required for the tumor-promoting and immune evasion effects of POFUT1 in HCC. Importantly, inhibition of POFUT1 could synergize with anti-programmed death receptor 1 therapy by remodeling TME in the xenograft tumor mouse model. Clinically, POFUT1 high expression displayed a lower response rate and worse clinical outcome to ICB therapies. Conclusions: Our findings demonstrate that POFUT1 functions as a novel regulator of tumor immune evasion and inhibition of POFUT1 may be a potential therapeutic strategy to enhance the efficacy of immune therapy in HCC.

Background: Hepatocellular carcinoma (HCC) is one of the major causes of death from cancer and has a very poor prognosis with few effective therapeutic options. Despite the approval of lenvatinib for the treatment of patients suffering from advanced HCC, only a small number of patients can benefit from this targeted therapy.Methods: Diethylnitrosamine (DEN)‐CCL4 mouse liver tumour and the xenograft tumour models were used to evaluate the function of KDM6A in HCC progression. The xenograft tumour model and HCC cell lines were used to evaluate the role of KDM6A in HCC drug sensitivity to lenvatinib. RNA‐seq and ChIP assays were conducted for mechanical investigation.Results: We revealed that KDM6A exhibited a significant upregulation in HCC tissues and was associated with an unfavourable prognosis. We further demonstrated that KDM6A knockdown remarkably suppressed HCC cell proliferation and migration in vitro. Moreover, hepatic Kdm6a loss also inhibited liver tumourigenesis in a mouse liver tumour model. Mechanistically, KDM6A loss downregulated the FGFR4 expression to suppress the PI3K–AKT–mTOR signalling pathway, leading to a glucose and lipid metabolism re‐programming in HCC. KDM6A and FGFR4 levels were positively correlated in HCC specimens and mouse liver tumour tissues. Notably, KDM6A knockdown significantly inhibited the efficacy of lenvatinib therapy in HCC cells in vitro and in vivo.Conclusions: Our findings revealed that KDM6A promoted HCC progression by activating FGFR4 expression and may be an essential molecule for influencing the efficacy of lenvatinib in HCC therapy.

Background and Aims: Epigenetic plasticity is a major challenge in cancer-targeted therapy. However, the molecular basis governing this process has not yet been clearly defined. Despite the considerable success of poly(ADP-ribose) polymerase inhibitors (PARPi) in cancer therapy, the limited response to PARPi, especially in HCC, has been a bottleneck in its clinical implications. Herein, we investigated the molecular basis of the histone methyltransferase KMT5C (lysine methyltransferase 5C) that governs PARPi sensitivity and explored a potential therapeutic strategy for enhancing PARPi efficacy. Approach and Results: We identified KMT5C, a trimethyltransferase of H4K20, as a targetable epigenetic factor that promoted liver tumor growth in mouse de novo MYC/Trp53 ^−/− and xenograft liver tumor models. Notably, induction of KMT5C by environmental stress was crucial for DNA repair and HCC cell survival. Mechanistically, KMT5C interacted with the pivotal component of homologous recombination repair, RAD51, and promoted RAD51/RAD54 complex formation, which was essential for the activation of dsDNA breaks repair. This effect depended on the methyltransferase activity of KMT5C. We further demonstrated that the function of KMT5C in promoting HCC progression was dependent on RAD51. Importantly, either a pharmacological inhibitor (A196) or genetic inhibition of KMT5C sensitized liver cancer cells to PARPi. Conclusions: KMT5C played a vital role in promoting liver cancer progression by activating the DNA repair response. Our results revealed a novel therapeutic approach using the KMT5C inhibitor A196, concurrent with olaparib, as a potential HCC therapy.