PD-L2 glycosylation promotes immune evasion and predicts anti-EGFR efficacy

Advances in cancer immunotherapy: historical perspectives, current developments, and future directions

Cancer immunotherapy, encompassing both experimental and standard-of-care therapies, has emerged as a promising approach to harnessing the immune system for tumor suppression. Experimental strategies, including novel immunotherapies and preclinical models, are actively being explored, while established treatments, such as immune checkpoint inhibitors (ICIs), are widely implemented in clinical settings. This comprehensive review examines the historical evolution, underlying mechanisms, and diverse strategies of cancer immunotherapy, highlighting both its clinical applications and ongoing preclinical advancements. The review delves into the essential components of anticancer immunity, including dendritic cell activation, T cell priming, and immune surveillance, while addressing the challenges posed by immune evasion mechanisms. Key immunotherapeutic strategies, such as cancer vaccines, oncolytic viruses, adoptive cell transfer, and ICIs, are discussed in detail. Additionally, the role of nanotechnology, cytokines, chemokines, and adjuvants in enhancing the precision and efficacy of immunotherapies were explored. Combination therapies, particularly those integrating immunotherapy with radiotherapy or chemotherapy, exhibit synergistic potential but necessitate careful management to reduce side effects. Emerging factors influencing immunotherapy outcomes, including tumor heterogeneity, gut microbiota composition, and genomic and epigenetic modifications, are also examined. Furthermore, the molecular mechanisms underlying immune evasion and therapeutic resistance are analyzed, with a focus on the contributions of noncoding RNAs and epigenetic alterations, along with innovative intervention strategies. This review emphasizes recent preclinical and clinical advancements, with particular attention to biomarker-driven approaches aimed at optimizing patient prognosis. Challenges such as immunotherapy-related toxicity, limited efficacy in solid tumors, and production constraints are highlighted as critical areas for future research. Advancements in personalized therapies and novel delivery systems are proposed as avenues to enhance treatment effectiveness and accessibility. By incorporating insights from multiple disciplines, this review aims to deepen the understanding and application of cancer immunotherapy, ultimately fostering more effective and widely accessible therapeutic solutions.

Identification of novel germline mutations in FUT7 and EXT1 linked with hereditary multiple exostoses

Hereditary multiple exostoses (HME) is an autosomal dominant skeletal disorder primarily linked with mutations in Exostosin-1 (EXT1) and Exostosin-2 (EXT2) genes. However, not all HME cases can be explained by these mutations, and its pathogenic mechanisms are not fully understood. Herein, utilizing whole-exome sequencing and genetic screening with a family trio design, we identify two novel rare mutations co-segregating with HME in a Chinese family, including a nonsense mutation (c.204G>A, p.Trp68*) in EXT1 and a missense mutation (c.893T>G, p.Phe298Cys) in FUT7. Functional assays reveal that the FUT7 mutation affects the cellular localization of FUT7 protein and regulates cell proliferation. Notably, the simultaneous loss of fut7 and ext1 in a zebrafish model results in severe chondrodysplasia, indicating a functional link between FUT7 and EXT1 in chondrocyte regulation. Additionally, we unveil that FUT7 p.Phe298Cys reduces EXT1 expression through IL6/STAT3/SLUG axis at the transcription level and through ubiquitination-related proteasomal degradation at the protein level. Together, our findings not only identify novel germline mutations in FUT7 and EXT1 genes, but also highlight the critical interaction between these genes, suggesting a potential 'second-hit' mechanism over EXT1 mutations in HME pathogenesis. This insight enhances our understanding of the mechanisms underlying HME and opens new avenues for potential therapeutic interventions.

Modulation of N-glycosylation in the PD-1: PD-L1 axis as a strategy to enhance cancer immunotherapies

The modulation of the N-glycosylation status in immune checkpoints, particularly the PD-1/PD-L1 axis, has emerged as a promising approach to enhance cancer immunotherapies. While immune checkpoint inhibitors (ICIs) targeting PD-1 and PD-L1 have achieved significant clinical success, recent studies highlight the critical role of N-glycosylation in regulating their expression, stability, and function. Alterations in N-glycosylation might affect the efficacy of ICIs by modulating the interactions between immune checkpoints and antibodies used in therapy. This review focuses on the glycosylation of PD-1 and its ligands PD-L1 and PD-L2, examining how N-glycans influence immune responses and contribute to immune evasion by tumors. It explores innovative strategies to modulate glycosylation in tumor and immune cells, including the use of N-glycosylation inhibitors and novel genetic manipulation techniques. Understanding the interplay between N-glycosylation and immune checkpoint functions is essential for optimizing immunotherapy outcomes and overcoming therapeutic resistance in cancer patients.

Post-translational modifications of immune checkpoints: unlocking new potentials in cancer immunotherapy

Immunotherapy targeting immune checkpoints has gained traction across various cancer types in clinical settings due to its notable advantages. Despite this, the overall response rates among patients remain modest, alongside issues of drug resistance and adverse effects. Hence, there is a pressing need to enhance immune checkpoint blockade (ICB) therapies. Post-translational modifications (PTMs) are crucial for protein functionality. Recent research emphasizes their pivotal role in immune checkpoint regulation, directly impacting the expression and function of these key proteins. This review delves into the influence of significant PTMs-ubiquitination, phosphorylation, and glycosylation-on immune checkpoint signaling. By targeting these modifications, novel immunotherapeutic strategies have emerged, paving the way for advancements in optimizing immune checkpoint blockade therapies in the future.

Divergent roles of PKM2 in regulating PD-L1 and PD-L2 expression and their implications in human and mouse cancer models

Cancer cells evade immune detection through checkpoint molecules like PD-L1 and PD-L2 which suppress T-cell activation. While PD-L1 is well-studied, the role of PD-L2 remains unclear. Pyruvate kinase M2 (PKM2), a metabolic enzyme, influences immune checkpoint regulation, but its role in PD-L1 and PD-L2 modulation is not well defined. Here, we investigate the role of pyruvate kinase M2 (PKM2) in modulating the immune checkpoint molecules PD-L1 and PD-L2 via GATA3 in cancer cells, with insights from both human and mouse models. We find that PKM2 enhances PD-L1 expression while inhibiting PD-L2, a dual regulatory mechanism that facilitates immune evasion. Knockdown and overexpression experiments revealed GATA3 as a key mediator. PKM2 knockout reduced GATA3 level, leading to decreased PD-L1 and increased PD-L2 expression. Chromatin immunoprecipitation (ChIP)-qPCR demonstrates that GATA3 functions as a direct transcription factor capable of binding to the promoters of PD-L1 and PD-L2. In silico analyses of 81 esophageal squamous cell carcinoma (ESCC) cases from the TCGA database demonstrate that PKM2 mRNA is unrelated to PD-L1 and PD-L2 expression but is negatively correlated with CD8 + T-cell infiltration in ESCC. To further validate these findings, we establish a xenograft model using immune-competent C57/BL6N mice, where knockdown of PKM2 results in significant downregulation of both PD-L1 and PD-L2 expression. Collectively, these findings underscore the divergent roles of PKM2 in regulating immune checkpoint expression in human and mouse cancer models and suggest that targeting the PKM2-GATA3 axis could enhance cancer immunotherapy by fine-tuning PD-L1 and PD-L2 levels.

Emerging roles of CircRNA-miRNA networks in cancer development and therapeutic response

The complex interplay of epigenetic factors is essential in regulating the hallmarks of cancer and orchestrating intricate molecular interactions during tumor progression. Circular RNAs (circRNAs), known for their covalently closed loop structures, are non-coding RNA molecules exceptionally resistant to enzymatic degradation, which enhances their stability and regulatory functions in cancer. Similarly, microRNAs (miRNAs) are endogenous non-coding RNAs with linear structures that regulate cellular biological processes akin to circRNAs. Both miRNAs and circRNAs exhibit aberrant expressions in various cancers. Notably, circRNAs can function as sponges for miRNAs, influencing their activity. The circRNA/miRNA interaction plays a pivotal role in the regulation of cancer progression, including in brain, gastrointestinal, gynecological, and urological cancers, influencing key processes such as proliferation, apoptosis, invasion, autophagy, epithelial-mesenchymal transition (EMT), and more. Additionally, this interaction impacts the response of tumor cells to radiotherapy and chemotherapy and contributes to immune evasion, a significant challenge in cancer therapy. Both circRNAs and miRNAs hold potential as biomarkers for cancer prognosis and diagnosis. In this review, we delve into the circRNA-miRNA circuit within human cancers, emphasizing their role in regulating cancer hallmarks and treatment responses. This discussion aims to provide insights for future research to better understand their functions and potentially guide targeted treatments for cancer patients using circRNA/miRNA-based strategies.

Glycosylation gene expression profiles enable prognosis prediction for colorectal cancer

This study developed a prognostic model for patients with colon adenocarcinoma (COAD) based on glycosylation-associated genes. By analyzing TCGA-COAD data, 110 key genes were identified, and a prognostic model incorporating five glycosylation-related genes was constructed. The model exhibits good predictive performance and is significantly associated with clinical features such as age, N stage, M stage, and lymph node count. The prognostic genes are involved in various biological processes and pathways, influence T cell differentiation, and may contribute to CRC development. High-risk patients show a higher degree of immune cell infiltration. This model aids in the early diagnosis, prognosis assessment, and treatment planning for CRC, and offers a direction for further research.

Construction and preclinical evaluation of a 124I-labelled bispecific antibody targeting PD-L1 and PD-L2

PURPOSE

NB12 is a bispecific antibody that consists of two anti-programmed cell death-ligand 1 (PD-L1) nanobodies and two anti-programmed cell death-ligand 2 (PD-L2) nanobodies. The aim of this study was to design a novel tracer, [124I]I-NB12, targeting PD-L1/2 and perform preclinical evaluations to dynamically monitor PD-L1/2 expression for determining cancer patient responsiveness to ICI therapy.

METHODS

NB12 was labelled with the radionuclide 124I at room temperature (RT). An in vitro binding assay was performed to assess the affinity of [124I]I-NB12 for PD-L1 and PD-L2. Cellular uptake, pharmacokinetic, and biodistribution experiments were performed to evaluate the biological properties. Micro-PET/CT imaging with [124I]I-NB12 was conducted at different time points. Immunohistochemical and haematoxylin and eosin (HE) staining experiments were carried out using tumour tissues. Routine blood, biochemical indices and major organ pathology were used to evaluate the biosafety of the tracers.

RESULTS

The radiochemical yield of [124I]I-NB12 was 84.62 ± 3.90%, and the radiochemical purity (RCP) was greater than 99%. [124I]I-NB12 had a high affinity for the PD-L1 (Kd = 19.82 nM) and PD-L2 (Kd = 2.93 nM). Cellular uptake experiments confirmed that the uptake of [124I]I-NB12 by A549-PDL1/2 cells was greater than that by A549 cells. The half-lives of the distribution phase and elimination phase were 0.26 h and 4.08 h, respectively. Micro-PET/CT showed significant [124I]I-NB12 uptake in the tumour region of A549-PDL1/2 tumour-bearing mice compared with A549 tumour-bearing mice 24 h postinjection. Immunohistochemical and HE staining experiments confirmed that tumour-bearing mice was successfully constructed.

CONCLUSION

We constructed a bispecific antibody that targets PD-L1 and PD-L2, namely, [124I]I-NB12. Biological evaluation revealed its specificity and affinity for PD-L1/2, and micro-PET/CT confirmed the feasibility of visualizing tumour PD-L1/2 in vivo. Using [124I]I-NB12 may be a promising strategy for identifying cancer patients that can potentially benefit from ICI therapy.

The future of genetic medicines delivered via targeted lipid nanoparticles to leukocytes

Genetic medicines hold vast therapeutic potential, offering the ability to silence or induce gene expression, knock out genes, and even edit DNA fragments. Applying these therapeutic modalities to leukocytes offers a promising path for treating various conditions yet overcoming the obstacles of specific and efficient delivery to leukocytes remains a major bottleneck in their clinical translation. Lipid nanoparticles (LNPs) have emerged as the leading delivery system for nucleic acids due to their remarkable versatility and ability to improve their in vivo stability, pharmacokinetics, and therapeutic benefits. Equipping LNPs with targeting moieties can promote their specific cellular uptake and internalization to leukocytes, making targeted LNPs (tLNPs) an inseparable part of developing leukocyte-targeted gene therapy. However, despite the significant advancements in research, genetic medicines for leukocytes using targeted delivery approaches have not been translated into the clinic yet. Herein, we discuss the important aspects of designing tLNPs and highlight the considerations for choosing an appropriate bioconjugation strategy and targeting moiety. Furthermore, we provide our insights on limiting challenges and identify key areas for further research to advance these exciting therapies for patient care.

Effect of Different Glucose Levels and Glycation on Meningioma Cell Migration and Invasion

Meningiomas are predominantly benign tumors, but there are also malignant forms that are associated with a poor prognosis. Like almost all tumors, meningiomas metabolize glucose as part of aerobic glycolysis (Warburg effect) for energy supply, so there are attempts to influence the prognosis of tumor diseases using a glucose-reduced diet. This altered metabolism leads to so called hallmarks of cancer, such as glycation and glycosylation. In this study, we investigated the influence of low (3 mM), normal (5.5 mM) and high glucose (15 mM) on a malignant meningioma cell line (IOMM-Lee, WHO grade 3). In addition, the influence of methylglyoxal, a by-product of glycolysis and a precursor for glycation, was investigated. Impedance-based methods (ECIS and RTCA) were used to study migration and invasion, and immunoblotting was used to analyze the expression of proteins relevant to these processes, such as focal adhesion kinase (FAK), merlin or integrin ß1. We were able to show that low glucose reduced the invasive potential of the cells, which was associated with a reduced amount of sialic acid. Under high glucose, barrier function was impaired and adhesion decreased, which correlated with a decreased expression of FAK.

CSE1L as a prognostic biomarker associated with pan cancer immune infiltration and drug sensitivity

BACKGROUND

Rising cancer-related mortality underscores the importance of biomarkers for treatment and prognosis, with Chromosome Segregation 1 Like (CSE1L) linked to various cancers yet its roles remain partially understood. This study investigates CSE1L's expression and oncogenic mechanisms in solid tumors.

RESEARCH DESIGN AND METHODS

We analyzed multi-omics data from 31 solid tumors, measured CSE1L in 41 head and neck carcinoma patients post-chemotherapy via qRT-PCR, and evaluated the impact of CSE1L knockdown on cell proliferation in A549 and HepG2 cells.

RESULTS

In this study, we observed significantly elevated levels of CSE1L RNA in 13 tumor tissues and protein levels in 8 tumor tissues compared to their corresponding adjacent normal tissues. Additionally, our investigation unveiled a correlation between heightened CSE1L expression in tumor tissues and worsened patient prognosis, poor response to immunotherapy, and diminished effectiveness of neoadjuvant chemotherapy. Through an analysis of CSE1L mechanisms, we discovered its potential involvement in promoting tumor cell proliferation, enhancing drug resistance, and influencing immune infiltration, thereby impacting patient prognosis and treatment outcomes. Finally, we delved into the potential mechanisms underlying upregulation of CSE1L in tumor tissues.

CONCLUSION

Our findings demonstrate that CSE1L promotes tumor development in various malignancies, highlighting its potential as both a therapeutic target and prognostic indicator.

Writers, readers, and erasers RNA modifications and drug resistance in cancer

Drug resistance in cancer cells significantly diminishes treatment efficacy, leading to recurrence and metastasis. A critical factor contributing to this resistance is the epigenetic alteration of gene expression via RNA modifications, such as N6-methyladenosine (m6A), N1-methyladenosine (m1A), 5-methylcytosine (m5C), 7-methylguanosine (m7G), pseudouridine (Ψ), and adenosine-to-inosine (A-to-I) editing. These modifications are pivotal in regulating RNA splicing, translation, transport, degradation, and stability. Governed by "writers," "readers," and "erasers," RNA modifications impact numerous biological processes and cancer progression, including cell proliferation, stemness, autophagy, invasion, and apoptosis. Aberrant RNA modifications can lead to drug resistance and adverse outcomes in various cancers. Thus, targeting RNA modification regulators offers a promising strategy for overcoming drug resistance and enhancing treatment efficacy. This review consolidates recent research on the role of prevalent RNA modifications in cancer drug resistance, with a focus on m6A, m1A, m5C, m7G, Ψ, and A-to-I editing. Additionally, it examines the regulatory mechanisms of RNA modifications linked to drug resistance in cancer and underscores the existing limitations in this field.

Results from a real-world study: a novel glycosyltransferase risk score for prognosis, tumor microenvironment phenotypes and immunotherapy in bladder cancer

BACKGROUND

Although immunotherapy shows tremendous potential in the treatment of bladder cancer (BLCA), the overall prognosis and response rates to immunotherapy in BLCA remain suboptimal.

METHODS

We performed an extensive evaluation of glycosyltransferase expression patterns in BLCA patients by analyzing 210 glycosyltransferase-related genes. Subsequently, we established correlations between these glycosyltransferase patterns, prognosis, and tumor microenvironment (TME) phenotypes. To offer personalized patient assessments, we developed a glycosyltransferase risk score that accurately predicts prognosis, TME phenotypes, and molecular subtypes. Importantly, we developed a RNA-seq cohort, named Xiangya cohort, to validate our results.

RESULTS

Two distinct patterns of glycosyltransferase expression were identified, corresponding to inflamed and noninflamed TME phenotypes, and demonstrated the potential to predict prognosis. We developed and validated a comprehensive risk score that accurately predicted individual patient prognosis in the TCGA-BLCA cohort. Additionally, we constructed a nomogram that integrated the risk score with several key clinical factors. Importantly, this risk score was successfully validated in external cohorts, including the Xiangya cohort and GSE48075. Furthermore, we discovered a positive correlation between this risk score and tumor-infiltrating lymphocytes in both the TCGA-BLCA and Xiangya cohorts, suggesting that patients with a higher risk score exhibited an inflamed TME phenotype and were more responsive to immunotherapy. Finally, we observed that the high and low risk score groups were consistent with the luminal and basal subtypes of BLCA, respectively, providing further validation of the risk score's role in the TME in terms of molecular subtypes.

CONCLUSIONS

Glycosyltransferase patterns exhibit distinct TME phenotypes in BLCA. Our comprehensive risk score provides a promising approach for prognostic prediction and assessment of immunotherapy efficacy, offering valuable guidance for precision medicine.

CXCL6-CXCR2 axis-mediated PD-L2+ mast cell accumulation shapes the immunosuppressive microenvironment in osteosarcoma

Osteosarcoma (OS) is the most common primary bone malignancy and has a high propensity for local invasion and metastasis. The tumour microenvironment of OS is infiltrated by a large number of immune cells, which play a crucial role in its progression and prognosis. Mast cells are important innate immune cells in the tumour stroma and exhibit different phenotypes in diverse tumour microenvironments. However, the underlying mechanisms of mast cell accumulation and the phenotypic characteristics of mast cells in OS remain poorly understood. In this article, we found for the first time that mast cell accumulation in osteosarcoma tissue was modulated by the CXCL6-CXCR2 axis and that the number of infiltrating mast cells was significantly greater in tumour tissues than in adjacent nontumour tissues. These tumour-infiltrating mast cells express high levels of the immunosuppressive molecule PD-L2, and survival analyses revealed that patients in the PD-L2+ high-expression group had a worse prognosis. In vitro, mast cells were induced to express PD-L2 in a time- and dose-dependent manner using OS tissue culture supernatants to mimic the tumour microenvironment. Mechanistic studies revealed that tumour cell-derived G-CSF significantly induced mast cell PD-L2 expression by activating STAT3. Importantly, mast cells overexpressing PD-L2 inhibit tumour-specific CD8+ T-cell proliferation and tumour-killing cytokine secretion, which is reversed by blocking PD-L2 on mast cells. Therefore, our findings provide new insight into the immunosuppressive and tumorigenic roles of mast cells, as well as a novel mechanism by which PD-L2-expressing mast cells mediate immune tolerance.

N-linked glycosylation of PD-L1/PD-1: an emerging target for cancer diagnosis and treatment

During tumorigenesis and progression, the immune checkpoint programmed death-1 (PD-1) and its ligand programmed death ligand-1 (PD-L1) play critical roles in suppressing T cell-mediated anticancer immune responses, leading to T-cell exhaustion and subsequent tumor evasion. Therefore, anti-PD-L1/PD-1 therapy has been an attractive strategy for treating cancer over the past decade. However, the overall efficacy of this approach remains suboptimal, revealing an urgent need for novel insights. Interestingly, increasing evidence indicates that both PD-L1 on tumor cells and PD-1 on tumor-specific T cells undergo extensive N-linked glycosylation, which is essential for the stability and interaction of these proteins, and this modification promotes tumor evasion. In various preclinical models, targeting the N-linked glycosylation of PD-L1/PD-1 was shown to significantly increase the efficacy of PD-L1/PD-1 blockade therapy. Furthermore, deglycosylation of PD-L1 strengthens the signal intensity in PD-L1 immunohistochemistry (IHC) assays, improving the diagnostic and therapeutic relevance of this protein. In this review, we provide an overview of the regulatory mechanisms underlying the N-linked glycosylation of PD-L1/PD-1 as well as the crucial role of N-linked glycosylation in PD-L1/PD-1-mediated immune evasion. In addition, we highlight the promising implications of targeting the N-linked glycosylation of PD-L1/PD-1 in the clinical diagnosis and treatment of cancer. Our review identifies knowledge gaps and sheds new light on the cancer research field.

Targeting STAT3 potentiates CDK4/6 inhibitors therapy in head and neck squamous cell carcinoma

Anti-CDK4/6 therapy has been employed for the treatment for head and neck squamous cell carcinoma (HNSCC) with CDK4/6 hyperactivation, but the response rate is relatively low. In this study, we first showed that CDK4 and CDK6 was over-expressed and conferred poor prognosis in HNSCC. Moreover, in RB-positive HNSCC, STAT3 signaling was activated induced by CDK4/6 inhibition and STAT3 promotes RB deficiency by upregulation of MYC. Thirdly, the combination of Stattic and CDK4/6 inhibitor results in striking anti-tumor effect in vitro and in Cal27 derived animal models. Additionally, phospho-STAT3 level negatively correlates with RB expression and predicts poor prognosis in patients with HNSCC. Taken together, our findings suggest an unrecognized function of STAT3 confers to CDK4/6 inhibitors resistance and presenting a promising combination strategy for patients with HNSCC.

Glycosylation and Its Role in Immune Checkpoint Proteins: From Molecular Mechanisms to Clinical Implications

Immune checkpoint proteins have become recent research hotspots for their vital role in maintaining peripheral immune tolerance and suppressing immune response function in a wide range of tumors. Therefore, investigating the immunomodulatory functions of immune checkpoints and their therapeutic potential for clinical use is of paramount importance. The immune checkpoint blockade (ICB) is an important component of cancer immunotherapy, as it targets inhibitory immune signaling transduction with antagonistic antibodies to restore the host immune response. Anti-programmed cell death-1 (PD-1) and anti-cytotoxic T lymphocyte-associated antigen-4 (CTLA-4) monoclonal antibodies are two main types of widely used ICBs that drastically improve the survival and prognosis of many patients with cancer. Nevertheless, the response rate of most cancer types remains relatively low due to the drug resistance of ICBs, which calls for an in-depth exploration to improve their efficacy. Accumulating evidence suggests that immune checkpoint proteins are glycosylated in forms of N-glycosylation, core fucosylation, or sialylation, which affect multiple biological functions of proteins such as protein biosynthesis, stability, and interaction. In this review, we give a brief introduction to several immune checkpoints and summarize primary molecular mechanisms that modulate protein stability and immunosuppressive function. In addition, newly developed methods targeting glycosylation on immune checkpoints for detection used to stratify patients, as well as small-molecule agents disrupting receptor-ligand interactions to circumvent drug resistance of traditional ICBs, in order to increase the clinical efficacy of immunotherapy strategies of patients with cancer, are also included to provide new insights into scientific research and clinical treatments.

Glycosylation in the tumor immune response: the bitter side of sweetness

Glycosylation is the most structurally diverse form of post-translational modification (PTM) of proteins that affects a myriad of cellular processes. As a pivotal regulator of protein homeostasis, glycosylation notably impacts the function of proteins, spanning from protein localization and stability to protein-protein interactions. Aberrant glycosylation is a hallmark of cancer, and extensive studies have revealed the multifaceted roles of glycosylation in tumor growth, migration, invasion and immune escape Over the past decade, glycosylation has emerged as an immune regulator in the tumor microenvironment (TME). Here, we summarize the intricate interplay between glycosylation and the immune system documented in recent literature, which orchestrates the regulation of the tumor immune response through endogenous lectins, immune checkpoints and the extracellular matrix (ECM) in the TME. In addition, we discuss the latest progress in glycan-based cancer immunotherapy. This review provides a basic understanding of glycosylation in the tumor immune response and a theoretical framework for tumor immunotherapy.

Diastereomers of Coibamide A Show Altered Sec61 Client Selectivity and Ligand-Dependent Activity against Patient-Derived Glioma Stem-like Cells

Coibamide A (CbA) is a cyanobacterial lariat depsipeptide that selectively inhibits multiple secreted and integral membrane proteins from entering the endoplasmic reticulum secretory pathway through binding the alpha subunit of the Sec61 translocon. As a complex peptide-based macrocycle with 13 stereogenic centers, CbA is presumed to adopt a conformationally restricted orientation in the ligand-bound state, resulting in potent antitumor and antiangiogenic bioactivity. A stereochemical structure-activity relationship for CbA was previously defined based on cytotoxicity against established cancer cell lines. However, the ability of synthetic isomers to inhibit the biosynthesis of specific Sec61 substrates was unknown. Here, we report that two less toxic diastereomers of CbA, [L-Hiv2]-CbA and [L-Hiv2, L-MeAla11]-CbA, are pharmacologically active Sec61 inhibitors. Both compounds inhibited the expression of a secreted reporter (Gaussia luciferase), VEGF-A, and a Type 1 membrane protein (VCAM1), while [L-Hiv2]-CbA also decreased the expression of ICAM1 and BiP/GRP78. Analysis of 43 different chemokines in the secretome of SF-268 glioblastoma cells revealed different inhibitory profiles for the two diastereomers. When the cytotoxic potential of CbA compounds was compared against a panel of patient-derived glioblastoma stem-like cells (GSCs), Sec61 inhibitors were remarkably toxic to five of the six GSCs tested. Each ligand showed a distinct cytotoxic potency and selectivity pattern for CbA-sensitive GSCs, with IC50 values ranging from subnanomolar to low micromolar concentrations. Together, these findings highlight the extreme sensitivity of GSCs to Sec61 modulation and the importance of ligand stereochemistry in determining the spectrum of inhibited Sec61 client proteins.

Deciphering Cholesterol's Role in PD-L2 Stability: A Distinct Regulatory Mechanism From PD-L1

Programmed cell death 1 ligand 2 (PD-L2), a member of the B7 immune checkpoint protein family, emerges as a crucial player in immune modulation. Despite its functional overlap with programmed cell death 1 ligand 1 (PD-L1) in binding to the programmed cell death protein 1 (PD-1) on T cells, PD-L2 exhibits a divergent expression pattern and a higher affinity for PD-1. However, the regulatory mechanisms of PD-L2 remain under-explored. Here, our investigations illustrate the pivotal role of cholesterol in modulating PD-L2 stability. Using advanced nuclear magnetic resonance (NMR) and biochemical analyses, we demonstrate a direct and specific binding between cholesterol and PD-L2, mediated by an F-xxx-V-xx-LR motif in its transmembrane domain, distinct from that in PD-L1. This interaction stabilizes PD-L2 and prevents its downstream degradation. Disruption of this binding motif compromises PD-L2's cellular stability, underscoring its potential significance in cancer biology. These findings not only deepen our understanding of PD-L2 regulation in the context of tumors, but also open avenues for potential therapeutic interventions.

Identification of stemness-related glycosylation changes in head and neck squamous cell carcinoma

BACKGROUND

Altered glycosylation is a hallmark of cancer associated with therapy resistance and tumor behavior. In this study, we investigated the glycosylation profile of stemness-related proteins OCT4, CIP2A, MET, and LIMA1 in HNSCC tumors.

METHODS

Tumor, adjacent normal tissue, and blood samples of 25 patients were collected together with clinical details. After tissue processing, lectin-based glycovariant screens were performed.

RESULTS

Strong correlation between glycosylation profiles of all four stemness-related proteins was observed in tumor tissue, whereas glycosylation in tumor tissue, adjacent normal tissue, and serum was differential.

CONCLUSIONS

A mannose- and galactose-rich glycosylation niche associated with stemness-related proteins was identified.

Targeting IL-6/STAT3 signaling abrogates EGFR-TKI resistance through inhibiting Beclin-1 dependent autophagy in HNSCC

Head and neck squamous cell carcinoma (HNSCC) is featured by notorious EGFR tyrosine kinase inhibitor (TKI) resistance attributable to activation of parallel pathways. The numerous phase I/II trials have rarely shown encouraging clinical outcomes of EGFR-TKIs during treatment in HNSCC patients with advanced tumors. A unique IL-6/STAT3 signaling axis is reported to regulate multiple cancer-related pathways, but whether this signaling is correlated with reduced EGFR-TKI responsiveness is unclear. Here, we found that STAT3 signaling is compensatorily upregulated after EGFR-TKI exposure and confers anti-EGFR therapy resistance during HNSCC therapy. Targeting STAT3 using small molecule inhibitors promotes complete recovery or sustained elimination of HNSCC tumors through combination with EGFR-TKIs both in vitro and in diverse animal models. Mechanistically, phosphorylated STAT3 was proven to enhance oncogenic autophagic flux, protecting cancer cells and preventing EGFR-TKI-induced tumor apoptosis. Thus, blockade of STAT3 signaling simultaneously disrupts several key interactions during tumor progression and remodels the autophagic degradation system, thereby rendering advanced HNSCC eradicable through combination with EGFR-TKI therapy. These findings provide a clinically actionable strategy and suggest STAT3 as a predictive biomarker with therapeutic potential for EGFR-TKI resistant HNSCC patients.

FUT8-mediated aberrant N-glycosylation of SEMA7A promotes head and neck squamous cell carcinoma progression

SEMA7A belongs to the Semaphorin family and is involved in the oncogenesis and tumor progression. Aberrant glycosylation has been intricately linked with immune escape and tumor growth. SEMA7A is a highly glycosylated protein with five glycosylated sites. The underlying mechanisms of SEMA7A glycosylation and its contribution to immunosuppression and tumorigenesis are unclear. Here, we identify overexpression and aberrant N-glycosylation of SEMA7A in head and neck squamous cell carcinoma, and elucidate fucosyltransferase FUT8 catalyzes aberrant core fucosylation in SEMA7A at N-linked oligosaccharides (Asn 105, 157, 258, 330, and 602) via a direct protein‒protein interaction. A glycosylated statue of SEMA7A is necessary for its intra-cellular trafficking from the cytoplasm to the cytomembrane. Cytokine EGF triggers SEMA7A N-glycosylation through increasing the binding affinity of SEMA7A toward FUT8, whereas TGF-β1 promotes abnormal glycosylation of SEMA7A via induction of epithelial-mesenchymal transition. Aberrant N-glycosylation of SEMA7A leads to the differentiation of CD8+ T cells along a trajectory toward an exhausted state, thus shaping an immunosuppressive microenvironment and being resistant immunogenic cell death. Deglycosylation of SEMA7A significantly improves the clinical outcome of EGFR-targeted and anti-PD-L1-based immunotherapy. Finally, we also define RBM4, a splice regulator, as a downstream effector of glycosylated SEMA7A and a pivotal mediator of PD-L1 alternative splicing. These findings suggest that targeting FUT8-SEMA7A axis might be a promising strategy for improving antitumor responses in head and neck squamous cell carcinoma patients.

Advances in immunotherapy for biliary tract cancers

ABSTRACT

Biliary tract cancers (BTC), a heterogeneous disease with poor prognosis, including gallbladder cancer (GBC), intrahepatic cholangiocarcinoma (ICC), and extrahepatic cholangiocarcinoma (ECC). Although surgery is currently the primary regimen to treat BTC, most BTC patients are diagnosed at an advanced stage and miss the opportunity of surgical eradication. As a result, non-surgical therapy serves as the main intervention for advanced BTC. In recent years, immunotherapy has emerged as one of the most promising therapies in a number of solid cancers, and it includes immune checkpoint inhibitors (ICIs) monotherapy or combined therapy, tumor vaccines, oncolytic virus immunotherapy, adoptive cell therapy (ACT), and cytokine therapy. However, these therapies have been practiced in limited clinical settings in patients with BTC. In this review, we focus on the discussion of latest advances of immunotherapy in BTC and update the progress of multiple current clinical trials with different immunotherapies.

Molecular basis, potential biomarkers, and future prospects of OSCC and PD-1/PD-L1 related immunotherapy methods

Oral squamous cell carcinoma (OSCC) affects a large number of individuals worldwide. Despite advancements in surgery, radiation, and chemotherapy, satisfactory outcomes have not been achieved. In recent years, the success of drugs targeting programmed cell death 1 (PD-1) and programmed cell death ligand 1 (PD-L1) has led to breakthroughs in cancer treatment, but systematic summaries on their effectiveness against OSCC are lacking. This article reviews the latest research on the PD-1/PD-L1 pathway and the potential of combination therapy based on this pathway in OSCC. Further, it explores the mechanisms involved in the interaction of this pathway with exosomes and protein-protein interactions, and concludes with potential future OSCC therapeutic strategies.

The significance of targeting lysosomes in cancer immunotherapy

Lysosomes are intracellular digestive organelles that participate in various physiological and pathological processes, including the regulation of immune checkpoint molecules, immune cell function in the tumor microenvironment, antigen presentation, metabolism, and autophagy. Abnormalities or dysfunction of lysosomes are associated with the occurrence, development, and drug resistance of tumors. Lysosomes play a crucial role and have potential applications in tumor immunotherapy. Targeting lysosomes or harnessing their properties is an effective strategy for tumor immunotherapy. However, the mechanisms and approaches related to lysosomes in tumor immunotherapy are not fully understood at present, and further basic and clinical research is needed to provide better treatment options for cancer patients. This review focuses on the research progress related to lysosomes and tumor immunotherapy in these.

The Multifaceted Role of FUT8 in Tumorigenesis: From Pathways to Potential Clinical Applications

FUT8, the sole glycosyltransferase responsible for N-glycan core fucosylation, plays a crucial role in tumorigenesis and development. Aberrant FUT8 expression disrupts the function of critical cellular components and triggers the abnormality of tumor signaling pathways, leading to malignant transformations such as proliferation, invasion, metastasis, and immunosuppression. The association between FUT8 and unfavorable outcomes in various tumors underscores its potential as a valuable diagnostic marker. Given the remarkable variation in biological functions and regulatory mechanisms of FUT8 across different tumor types, gaining a comprehensive understanding of its complexity is imperative. Here, we review how FUT8 plays roles in tumorigenesis and development, and how this outcome could be utilized to develop potential clinical therapies for tumors.

Immune Escape Strategies in Head and Neck Cancer: Evade, Resist, Inhibit, Recruit

Head and neck cancers (HNCs) arise from the mucosal lining of the aerodigestive tract and are often associated with alcohol use, tobacco use, and/or human papillomavirus (HPV) infection. Over 600,000 new cases of HNC are diagnosed each year, making it the sixth most common cancer worldwide. Historically, treatments have included surgery, radiation, and chemotherapy, and while these treatments are still the backbone of current therapy, several immunotherapies have recently been approved by the Food and Drug Administration (FDA) for use in HNC. The role of the immune system in tumorigenesis and cancer progression has been explored since the early 20th century, eventually coalescing into the current three-phase model of cancer immunoediting. During each of the three phases-elimination, equilibrium, and escape-cancer cells develop and utilize multiple strategies to either reach or remain in the final phase, escape, at which point the tumor is able to grow and metastasize with little to no detrimental interference from the immune system. In this review, we summarize the many strategies used by HNC to escape the immune system, which include ways to evade immune detection, resist immune cell attacks, inhibit immune cell functions, and recruit pro-tumor immune cells.

N-linked glycans: an underappreciated key determinant of T cell development, activation, and function

N-linked glycosylation is a post-translational modification that results in the decoration of newly synthesized proteins with diverse types of oligosaccharides that originate from the amide group of the amino acid asparagine. The sequential and collective action of multiple glycosidases and glycosyltransferases are responsible for determining the overall size, composition, and location of N-linked glycans that become covalently linked to an asparagine during and after protein translation. A growing body of evidence supports the critical role of N-linked glycan synthesis in regulating many features of T cell biology, including thymocyte development and tolerance, as well as T cell activation and differentiation. Here, we provide an overview of how specific glycosidases and glycosyltransferases contribute to the generation of different types of N-linked glycans and how these post-translational modifications ultimately regulate multiple facets of T cell biology.

PD-1-Targeted Immunotherapy: The Ligand Matters

This Pillars of Immunology article is a commentary on “PD-L2 is a second ligand for PD-1 and inhibits T cell activation,” a pivotal article written by Y. Latchman, C. R. Wood, T. Chernova, D. Chaudhary, M. Borde, I. Chernova, Y. Iwai, A. J. Long, J. A. Brown, R. Nunes, E. A. Greenfield, K. Bourque, V. A. Boussiotis, L. L. Carter, B. M. Carreno, N. Malenkovich, H. Nishimura, T. Okazaki, T. Honjo, A. H. Sharpe, and G. J. Freeman, and published in Nature Immunology, in 2001. https://www.nature.com/articles/ni0301_261.

Application of single-cell RNA sequencing in head and neck squamous cell carcinoma

Single-cell RNA sequencing has been broadly applied to head and neck squamous cell carcinoma (HNSCC) for characterizing the heterogeneity and genomic mutations of HNSCC benefiting from the advantage of single-cell resolution. We summarized most of the current studies and aimed to explore their research methods and ideas, as well as how to transform them into clinical applications. Through single-cell RNA sequencing, we found the differences in tumor cells' expression programs and differentiation tracks. The studies of immune microenvironment allowed us to distinguish immune cell subpopulations, the extensive expression of immune checkpoints, and the complex crosstalk network between immune cells and non-immune cells. For cancer-associated fibroblasts (CAFs), single-cell RNA sequencing had made an irreplaceable contribution to the exploration of their differentiation status, specific CAFs markers, and the interaction with tumor cells and immune cells. In addition, we demonstrated in detail how single-cell RNA sequencing explored the HNSCC epithelial-to-mesenchymal transition (EMT) model and the mechanism of drug resistance, as well as its clinical value.

Aptamers Targeting the PD-1/PD-L1 Axis: A Perspective

Aptamers have emerged in recent years as alternatives to antibodies or small molecules to interfere with the immune check points by blocking the PD-1/PD-L1 interactions and represent an interesting perspective for immuno-oncology. Aptamers are RNA or DNA nucleotides able to bind to a target with high affinity, with the target ranging from small molecules to proteins and up to cells. Aptamers are identified by the SELEX method that can be modified for specific purposes. The range of applications of aptamers covers therapy as well as new alternative assay technologies similar to ELISA. Aptamers' limited plasma stability can be managed using delivery strategies. The goal of this Perspective is to give an overview of the current development of aptamers targeting the most studied immune checkpoint modulators, PD-1 and PD-L1, and analogous strategies with aptamers for other immuno-related targets.

SEC61G assists EGFR-amplified glioblastoma to evade immune elimination

Amplification of chromosome 7p11 (7p11) is the most common alteration in primary glioblastoma (GBM), resulting in gains of epidermal growth factor receptor (EGFR) copy number in 50 to 60% of GBM tumors. However, treatment strategies targeting EGFR have thus far failed in clinical trials, and the underlying mechanism remains largely unclear. We here demonstrate that EGFR amplification at the 7p11 locus frequently encompasses its neighboring genes and identifies SEC61G as a critical regulator facilitating GBM immune evasion and tumor growth. We found that SEC61G is always coamplified with EGFR and is highly expressed in GBM. As an essential subunit of the SEC61 translocon complex, SEC61G promotes translocation of newly translated immune checkpoint ligands (ICLs, including PD-L1, PVR, and PD-L2) into the endoplasmic reticulum and promotes their glycosylation, stabilization, and membrane presentation. Depletion of SEC61G promotes the infiltration and cytolytic activity of CD8+ T cells and thus inhibits GBM occurrence. Further, SEC61G inhibition augments the therapeutic efficiency of EGFR tyrosine kinase inhibitors in mice. Our study demonstrates a critical role of SEC61G in GBM immune evasion, which provides a compelling rationale for combination therapy of EGFR-amplified GBMs.

Lysine methylation promotes NFAT5 activation and determines temozolomide efficacy in glioblastoma

Temozolomide (TMZ) therapy offers minimal clinical benefits in patients with glioblastoma multiforme (GBM) with high EGFR activity, underscoring the need for effective combination therapy. Here, we show that tonicity-responsive enhancer binding protein (NFAT5) lysine methylation, is a determinant of TMZ response. Mechanistically, EGFR activation induces phosphorylated EZH2 (Ser21) binding and triggers NFAT5 methylation at K668. Methylation prevents NFAT5 cytoplasm interaction with E3 ligase TRAF6, thus blocks NFAT5 lysosomal degradation and cytosol localization restriction, which was mediated by TRAF6 induced K63-linked ubiquitination, resulting in NFAT5 protein stabilization, nuclear accumulation and activation. Methylated NFAT5 leads to the upregulation of MGMT, a transcriptional target of NFAT5, which is responsible for unfavorable TMZ response. Inhibition of NFAT5 K668 methylation improved TMZ efficacy in orthotopic xenografts and patient-derived xenografts (PDX) models. Notably, NFAT5 K668 methylation levels are elevated in TMZ-refractory specimens and confer poor prognosis. Our findings suggest targeting NFAT5 methylation is a promising therapeutic strategy to improve TMZ response in tumors with EGFR activation.

Targeting protein glycosylation to regulate inflammation in the respiratory tract: novel diagnostic and therapeutic candidates for chronic respiratory diseases

Protein glycosylation is a widespread posttranslational modification that can impact the function of proteins. Dysregulated protein glycosylation has been linked to several diseases, including chronic respiratory diseases (CRDs). CRDs pose a significant public health threat globally, affecting the airways and other lung structures. Emerging researches suggest that glycosylation plays a significant role in regulating inflammation associated with CRDs. This review offers an overview of the abnormal glycoenzyme activity and corresponding glycosylation changes involved in various CRDs, including chronic obstructive pulmonary disease, asthma, cystic fibrosis, idiopathic pulmonary fibrosis, pulmonary arterial hypertension, non-cystic fibrosis bronchiectasis, and lung cancer. Additionally, this review summarizes recent advances in glycomics and glycoproteomics-based protein glycosylation analysis of CRDs. The potential of glycoenzymes and glycoproteins for clinical use in the diagnosis and treatment of CRDs is also discussed.

Inside PD-1/PD-L1,2 with their inhibitors

This review summarizes current knowledge in the development of immune checkpoint inhibitors, including antibodies and small molecules.

Aberrant protein glycosylation: Implications on diagnosis and Immunotherapy

Glycosylation-mediated post-translational modification is critical for regulating many fundamental processes like cell division, differentiation, immune response, and cell-to-cell interaction. Alterations in the N-linked or O-linked glycosylation pattern of regulatory proteins like transcription factors or cellular receptors lead to many diseases, including cancer. These alterations give rise to micro- and macro-heterogeneity in tumor cells. Here, we review the role of O- and N-linked glycosylation and its regulatory function in autoimmunity and aberrant glycosylation in cancer. The change in cellular glycome could result from a change in the expression of glycosidases or glycosyltransferases like N-acetyl-glucosaminyl transferase V, FUT8, ST6Gal-I, DPAGT1, etc., impact the glycosylation of target proteins leading to transformation. Moreover, the mutations in glycogenes affect glycosylation patterns on immune cells leading to other related manifestations like pro- or anti-inflammatory effects. In recent years, understanding the glycome to cancer indicates that it can be utilized for both diagnosis/prognosis as well as immunotherapy. Studies involving mass spectrometry of proteome, site- and structure-specific glycoproteomics, or transcriptomics/genomics of patient samples and cancer models revealed the importance of glycosylation homeostasis in cancer biology. The development of emerging technologies, such as the lectin microarray, has facilitated research on the structure and function of glycans and glycosylation. Newly developed devices allow for high-throughput, high-speed, and precise research on aberrant glycosylation. This paper also discusses emerging technologies and clinical applications of glycosylation.

Beyond antibody fucosylation: α-(1,6)-fucosyltransferase (Fut8) as a potential new therapeutic target for cancer immunotherapy

Aberrant post-translational glycosylation is a well-established hallmark of cancer. Altered core fucosylation mediated by α-(1,6)-fucosyltransferase (Fut8) is one of the key changes in tumor glycan patterns that contributes to neoplastic transformation, tumor metastasis, and immune evasion. Increased Fut8 expression and activity are associated with many types of human cancers, including lung, breast, melanoma, liver, colorectal, ovarian, prostate, thyroid, and pancreatic cancer. In animal models, inhibition of Fut8 activity by gene knockout, RNA interference, and small analogue inhibitors led to reduced tumor growth/metastasis, downregulation of immune checkpoint molecules PD-1, PD-L1/2, and B7-H3, and reversal of the suppressive state of tumor microenvironment. Although the biologics field has long benefited tremendously from using FUT8 -/- Chinese hamster ovary cells to manufacture IgGs with greatly enhanced effector function of antibody-dependent cellular cytotoxicity for therapy, it is only in recent years that the roles of Fut8 itself in cancer biology have been studied. Here, we summarize the pro-oncogenic mechanisms involved in cancer development that are regulated by Fut8-mediated core fucosylation, and call for more research in this area where modifying the activity of this sole enzyme responsible for core fucosylation could potentially bring rewarding surprises in fighting cancer, infections, and other immune-related diseases.

Sequential genome-wide CRISPR-Cas9 screens identify genes regulating cell-surface expression of tetraspanins

Tetraspanins, a superfamily of membrane proteins, mediate diverse biological processes through tetraspanin-enriched microdomains in the plasma membrane. However, how their cell-surface presentation is controlled remains unclear. To identify the regulators of tetraspanin trafficking, we conduct sequential genome-wide loss-of-function CRISPR-Cas9 screens based on cell-surface expression of a tetraspanin member, TSPAN8. Several genes potentially involved in endoplasmic reticulum (ER) targeting, different biological processes in the Golgi apparatus, and protein trafficking are identified and functionally validated. Importantly, we find that biantennary N-glycans generated by MGAT1/2, but not more complex glycan structures, are important for cell-surface tetraspanin expression. Moreover, we unravel that SPPL3, a Golgi intramembrane-cleaving protease reported previously to act as a sheddase of multiple glycan-modifying enzymes, controls cell-surface tetraspanin expression through a mechanism associated with lacto-series glycolipid biosynthesis. Our study provides critical insights into the molecular regulation of cell-surface presentation of tetraspanins with implications for strategies to manipulate their functions, including cancer cell invasion.

Novel Insights of Anti-EGFR Therapy in HNSCC: Combined with Immunotherapy or Not?

PURPOSE OF REVIEW

The efficacy of anti-EGFR therapy is still unfavorable in recurrent or metastatic head and neck squamous cell carcinoma (HNSCC) patients. Disorder of antitumor immunity and aberrantly expressed checkpoint biomarkers had been validated to involve anti-EGFR therapy tolerance and efficacy. Here we review the immunomodulation of anti-EGFR therapy in the tumor immune microenvironment (TIME) of HNSCC and assist clinicians in finding the potential strategies to rescue anti-EGFR tolerance therapy in the era of immunotherapy for HNSCC.

RECENT FINDINGS

Anti-EGFR therapy, especially cetuximab, was validated to induce the innate and adaptive immune responses of HNSCC patients. It is mainly through inducing natural killer (NK) cells mediating antibody-dependent cell-mediated cytotoxicity (ADCC), recruiting multiple tumor-infiltrating immune cells, and finally remodeling the TIME. Moreover, mountains of preclinical models and clinical trials revealed that combining anti-EGFR agents with immunotherapy could enhance the antitumor effectiveness in HNSCC. Anti-EGFR therapy may usher in another dawn in the treatment of patients with HNSCC through combination with immunotherapy. We offer an overview of the ongoing efforts to make out the immunomodulation of the EGFR pathway in both innate and adaptive immune responses; update the constant preclinical models and clinical trials for the combination of anti-EGFR and immunotherapy in HNSCC; and finally evaluate the efficacy and advantages of the combination therapeutic strategies in clinical use.

Combined PARP inhibitors and small molecular inhibitors in solid tumor treatment (Review)

With the development of precision medicine, targeted therapy has attracted extensive attention. Poly(ADP‑ribose) polymerase inhibitors (PARPi) are critical clinical drugs designed to induce cell death and are major antitumor targeted agents. However, preclinical and clinical data have revealed the limitations of PARPi monotherapy. Therefore, their combination with other targeted drugs has become a research hotspot in tumor treatment. Recent studies have demonstrated the critical role of small molecular inhibitors in multiple haematological cancers and solid tumors via cellular signalling modulation, exhibiting potential as a combined pharmacotherapy. In the present review, studies focused on small molecular inhibitors targeting the homologous recombination pathway were summarized and clinical trials evaluating the safety and efficacy of combined treatment were discussed.

ARHGAP21 Is Involved in the Carcinogenic Mechanism of Cholangiocarcinoma: A Study Based on Bioinformatic Analyses and Experimental Validation

Background and Objectives: Rho GTPase-activating protein (RhoGAP) is a negative regulatory element of Rho GTPases and participates in tumorigenesis. Rho GTPase-activating protein 21 (ARHGAP21) is one of the RhoGAPs and its role in cholangiocarcinoma (CCA) has never been disclosed in any publications. Materials and Methods: The bioinformatics public datasets were utilized to investigate the expression patterns and mutations of ARHGAP21 as well as its prognostic significance in CCA. The biological functions of ARHGAP21 in CCA cells (RBE and Hccc9810 cell) were evaluated by scratch assay, cell counting kit-8 assay (CCK8) assay, and transwell migration assay. In addition, the underlying mechanism of ARHGAP21 involved in CCA was investigated by the Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis, and the most significant signaling pathway was identified through gene set enrichment analysis (GSEA) and the Western blot method. The ssGSEA algorithm was further used to explore the immune-related mechanism of ARHGAP21 in CCA. Results: The ARHGAP21 expression in CCA tissue was higher than it was in normal tissue, and missense mutation was the main alteration of ARHGAP21 in CCA. Moreover, the expression of ARHGAP21 had obvious differences in patients with different clinical characteristics and it had great prognostic significance. Based on cell experiments, we further observed that the proliferation ability and migration ability of the ARHGAP21-knockdown group was reduced in CCA cells. Several pathological signaling pathways correlated with proliferation and migration were determined by GO and KEGG analysis. Furthermore, the PI3K/Akt signaling pathway was the most significant one. GSEA analysis further verified that ARHGAP21 was highly enriched in PI3K/Akt signaling pathway, and the results of Western blot suggested that the phosphorylated PI3K and Akt were decreased in the ARHGAP21-knockdown group. The drug susceptibility of the PI3K/Akt signaling pathway targeted drugs were positively correlated with ARHGAP21 expression. Moreover, we also discovered that ARHGAP21 was correlated with neutrophil, pDC, and mast cell infiltration as well as immune-related genes in CCA. Conclusions: ARHGAP21 could promote the proliferation and migration of CCA cells by activating the PI3K/Akt signaling pathway, and ARHGAP21 may participate in the immune modulating function of the tumor microenvironment.

Evolving landscape of PD-L2: bring new light to checkpoint immunotherapy

Immune checkpoint blockade therapy targeting programmed cell death protein 1 (PD-1) has revolutionized the landscape of multiple human cancer types, including head and neck squamous carcinoma (HNSCC). Programmed death ligand-2 (PD-L2), a PD-1 ligand, mediates cancer cell immune escape (or tolerance independent of PD-L1) and predicts poor prognosis of patients with HNSCC. Therefore, an in-depth understanding of the regulatory process of PD-L2 expression may stratify patients with HNSCC to benefit from anti-PD-1 immunotherapy. In this review, we summarised the PD-L2 expression and its immune-dependent and independent functions in HNSCC and other solid tumours. We focused on recent findings on the mechanisms that regulate PD-L2 at the genomic, transcriptional, post-transcriptional, translational, and post-translational levels, also in intercellular communication of tumour microenvironment (TME). We also discussed the prospects of using small molecular agents indirectly targeting PD-L2 in cancer therapy. These findings may provide a notable avenue in developing novel and effective PD-L2-targeted therapeutic strategies for immune combination therapy and uncovering biomarkers that improve the clinical efficacy of anti-PD-1 therapies.

B7 family protein glycosylation: Promising novel targets in tumor treatment

Cancer immunotherapy, including the inhibition of immune checkpoints, improves the tumor immune microenvironment and is an effective tool for cancer therapy. More effective and alternative inhibitory targets are critical for successful immune checkpoint blockade therapy. The interaction of the immunomodulatory ligand B7 family with corresponding receptors induces or inhibits T cell responses by sending co-stimulatory and co-inhibitory signals respectively. Blocking the glycosylation of the B7 family members PD-L1, PD-L2, B7-H3, and B7-H4 inhibited the self-stability and receptor binding of these immune checkpoint proteins, leading to immunosuppression and rapid tumor progression. Therefore, regulation of glycosylation may be the "golden key" to relieve tumor immunosuppression. The exploration of a more precise glycosylation regulation mechanism and glycan structure of B7 family proteins is conducive to the discovery and clinical application of antibodies and small molecule inhibitors.

The Glycosylation of Immune Checkpoints and Their Applications in Oncology

Tumor therapies have entered the immunotherapy era. Immune checkpoint inhibitors have achieved tremendous success, with some patients achieving long-term tumor control. Tumors, on the other hand, can still accomplish immune evasion, which is aided by immune checkpoints. The majority of immune checkpoints are membrane glycoproteins, and abnormal tumor glycosylation may alter how the immune system perceives tumors, affecting the body's anti-tumor immunity. Furthermore, RNA can also be glycosylated, and GlycoRNA is important to the immune system. Glycosylation has emerged as a new hallmark of tumors, with glycosylation being considered a potential therapeutic approach. The glycosylation modification of immune checkpoints and the most recent advances in glycosylation-targeted immunotherapy are discussed in this review.

Lactobacillus johnsonii alleviates colitis by TLR1/2-STAT3 mediated CD206+ macrophagesIL-10 activation

Imbalance of gut microbiota homeostasis is related to the occurrence of ulcerative colitis (UC), and probiotics are thought to modulate immune microenvironment and repair barrier function. Here, in order to reveal the interaction between UC and gut microbiota, we screened a new probiotic strain by 16S rRNA sequencing from Dextran Sulfate Sodium (DSS)-induced colitis mice, and explored the mechanism and clinical relevance. Lactobacillus johnsonii (L. johnsonii), as a potential anti-inflammatory bacterium was decreased colonization in colitis mice. Gavage L. johnsonii could alleviate colitis by specifically increasing the proportion of intestinal macrophages and the secretion of Il-10 with macrophages depleted model and in Il10^-/- mice. We identified this subset of immune cells activated by L. johnsonii as CD206⁺ macrophages^IL-10. Mechanistically, L. johnsonii supplementation enhanced the mobilization of CD206⁺ macrophages^IL-10 through the activation of STAT3 in vivo and in vitro. In addition, we revealed that TLR1/2 was essential for the activation of STAT3 and the recognition of L. johnsonii by macrophages. Clinically, there was positive correlation between the abundance of L. johnsonii and the expression level of MRC1, IL10 and TLR1/2 in UC tissues. L. johnsonii could activate native macrophages into CD206⁺ macrophages and release IL-10 through TLR1/2-STAT3 pathway to relieve experimental colitis. L. johnsonii may serve as an immunomodulator and anti-inflammatory therapeutic target for UC.

Expression of Programmed Death Ligand-2 is associated with Prognosis in Nasopharyngeal Carcinoma Microenviroment

Background: Although immune checkpoint inhibitors have opened a new mode of treatment for solid tumors, their efficacy in nasopharyngeal carcinoma (NPC) needs to be further investigated. Inhibitors of the PD-1/PD-L1 immune checkpoint are one of the hot topics in tumor immunotherapy. Programmed death ligand-2 (PD-L2) is a less studied ligand of PD-1 and has not yet been fully explored, especially in NPC. Understanding the clinical significance of PD-L2 expression, together with immune cell infiltration, might provide clues for biomarker screening in NPC immunotherapy. This study aimed to evaluate the role of PD-L2 as a prognostic factor for NPC patients as well as its role in immune regulation. Methods: Immunohistochemistry (IHC) was performed on a tissue microarray including 557 NPC specimens using PD-L2 antibody. The immune cell markers CD4, FOXP3 and CD68 were also stained and quantified. The expression of PD-L2 exhibited different spatial patterns among NPC tumor and stromal tissues. Results: A total of 90.8% of the cases showed membranous PD-L2 expression in tumors, and 80.8% showed membranous PD-L2 expression in stromal tissue. High stromal expression of PD-L2 predicted favorable overall and disease-free survival of NPC patients and was negatively correlated with tumor size, recurrence or metastasis and clinical stage. In contrast, high tumor abundance of PD-L2 correlated with poor disease-free survival, but had no obvious correlation with clinicopathological parameters. Multivariate analysis indicated that stromal PD-L2 was an independent and favorable prognostic factor. Furthermore, we found a positive correlation between stromal PD-L2 expression and the infiltration of CD68⁺ macrophages and CD4⁺Foxp3⁺ Treg cells in NPC stromal tissues (Pearson correlation=0.181 and 0.098, respectively). Conclusions: Our results suggest that different PD-L2 expression patterns have distinct predictive values. PD-L2 expressed on stromal cells might play a role in the regulation of NPC progression, and involve in immune activation in the tissue microenvironment and have an independent good prognosis for NPC patients.

Siglec-15-induced autophagy promotes invasion and metastasis of human osteosarcoma cells by activating the epithelial-mesenchymal transition and Beclin-1/ATG14 pathway

BACKGROUND

Pulmonary metastasis is the main cause of poor prognosis in osteosarcoma. Sialic acid-bound immunoglobulin lectin 15 (Siglec-15) has been demonstrated to be obviously correlated with pulmonary metastasis in osteosarcoma patients. However, the effect of Siglec-15 on autophagy in osteosarcoma remains unclear, while the role and mechanism of Siglec-15-related autophagy in lung metastasis also remain unknown.

METHODS

The expression levels of Siglec-15 and Beclin-1 were detected in osteosarcoma tissues using immunohistochemistry (IHC). The effect of Siglec-15 on metastasis was investigated using Transwell, wound healing and animal experiments with osteosarcoma cells. Corresponding proteins were confirmed using Western blotting when Siglec-15 or Beclin-1 was silenced or overexpressed. Changes in autophagy and the cytoskeleton were detected using immunofluorescence and transmission electron microscopy.

RESULTS

Siglec-15 and Beclin-1 expression was evaluated both in lung metastases and in patients who presented with pulmonary metastasis of osteosarcoma. Immunoprecipitation experiments revealed that Siglec-15 interacts directly with Beclin-1, an important autophagic protein. Moreover, loss of Siglec-15 distinctly inhibited autophagy and reduced Beclin-1/ATG14 expression. The decreased invasion and migration caused by Siglec-15 silencing could be reversed by Beclin-1 overexpression. Additionally, autophagy can promote the epithelial-mesenchymal transition (EMT) and affect cytoskeletal rearrangement, which was confirmed by overexpression or silencing of Beclin-1.

CONCLUSIONS

These findings confirmed the role of Siglec-15 in the regulation of autophagy and elaborated the relationship and mechanisms between autophagy and the metastasis of osteosarcoma cells.

Glycosylation and its research progress in endometrial cancer

Endometrial cancer (EC) is one of the most common tumors in the female reproductive system, which seriously threatens women's health, particularly in developed countries. 13% of the patients with EC have a poor prognosis due to recurrence and metastasis. Therefore, identifying good predictive biomarkers and therapeutic targets is critical to enable the early detection of metastasis and improve the prognosis. For decades, extensive studies had focused on glycans and glycoproteins in the progression of cancer. The types of glycans that are covalently attached to the polypeptide backbone, usually via nitrogen or oxygen linkages, are known as N‑glycans or O‑glycans, respectively. The degree of protein glycosylation and the aberrant changes in the carbohydrate structures have been implicated in the extent of tumorigenesis and reported to play a critical role in regulating tumor invasion, metabolism, and immunity. This review summarizes the essential biological role of glycosylation in EC, with a focus on the recent advances in glycomics and glycosylation markers, highlighting their implications in the diagnosis and treatment of EC.

Recent Advances and Next Breakthrough in Immunotherapy for Cancer Treatment

With the huge therapeutic potential, cancer immunotherapy is expected to become the mainstream of cancer treatment. In the current field of cancer immunotherapy, there are mainly five types. Immune checkpoint blockade therapy is one of the most promising directions. Adoptive cell therapy is an important component of cancer immunotherapy. The therapy with the cancer vaccine is promising cancer immunotherapy capable of cancer prevention. Cytokine therapy is one of the pillars of cancer immunotherapy. Oncolytic immunotherapy is a promising novel component of cancer immunotherapy, which with significantly lower incidence of serious adverse reactions. The recent positive results of many clinical trials with cancer immunotherapy may herald good clinical prospects. But there are still many challenges in the broad implementation of immunotherapy. Such as the immunotherapy cannot act on all tumors, and it has serious adverse effects including but not limited to nonspecific and autoimmunity inflammation. Here, we center on recent progress made within the last 5 years in cancer immunotherapy. And we discuss the theoretical background, as well as the opportunities and challenges of cancer immunotherapy.