Removal of N-Linked Glycosylation Enhances PD-L1 Detection and Predicts Anti-PD-1/PD-L1 Therapeutic Efficacy

Exosomal PD-L1 derived from hypoxia nasopharyngeal carcinoma cell exacerbates CD8+ T cell suppression by promoting PD-L1 upregulation in macrophages

Immunotherapy targeting the programmed death ligand-1/programmed cell death protein-1 (PD-L1/PD-1) pathway exhibits limited effectiveness in individuals with recurrent and metastatic nasopharyngeal carcinoma (NPC). Recent studies have noted that hypoxia within the tumor microenvironment (TME) triggers intricate interplay, termed "hypoxia-induced exosome-mediated communication", between cancer cells and various immune cells. However, the role of hypoxia in modulating the immunosuppressive environment and its implications on the efficacy of immunotherapy in NPC remains poorly understood. In this study, we found hypoxia inducible factor-1 (HIF-1α) was positively associated with increased PD-L1 levels and decreased CD8+ T cell infiltration, and correlated with a poor prognosis. Mechanistically, we demonstrated that hypoxia regulated the expression of PD-L1 in NPC cells and their exosomes by activating the binding of HIF-1α to the PD-L1 promoter. Meanwhile, using in vitro approaches, we found that macrophages could upregulate their PD-L1 expression through the phagocytosis of exosomal PD-L1 derived from NPC cells. Furthermore, we confirmed that PD-L1+ macrophages could induce CD8+ T cell exhaustion and reduce their proliferation. In conclusion, our study revealed that hypoxia (via HIF-1α) upregulated the expression of PD-L1 in exosomes derived from NPC cells, while macrophages induce the suppression of CD8+ T cells by phagocytosis of exosomal PD-L1. Targeting the PD-L1+ macrophages could potentially serve as a promising approach to augment the effectiveness of immune checkpoint blockade in NPC.

Inhibitory effects of β-galactoside α2,6-sialyltransferase 1 on the Hippo pathway in breast cancer cells

The Hippo signaling pathway is crucial in pathological functions such as tumors. Yes-associated protein (YAP), a well-known downstream effector of the Hippo pathway, has been intensively studied; emerging evidence suggests that multiple cell membrane receptors can regulate the Hippo pathway. However, the mechanistic roles of these upstream pathways remain largely unknown. Here, we identified the β-galactoside α2,6-sialyltransferase 1 (ST6GAL1) catalyzed α2,6-sialylation as a pivotal upstream modulator of Hippo pathway by a glycosyltransferases (GTs) overexpression sub-library screening. Depletion of ST6GAL1 results in increased phosphorylation of LATS1 and YAP, which induces YAP's nuclear localization, transcriptional activity, and multiple biological functions in breast cancer cells, including cell adhesion, spreading, growth, migration, and metastasis. These phenotypes were majorly due to the altered signal transduction of cell surface receptors, as deletion of ST6GAL1 exhibited attenuated GPCR, EGFR, and Integrins response and suppression of dephosphorylation of YAP. Mechanistically, these representative membrane receptors are α2,6-sialylated proteins, and their α2,6-sialylation could be inhibited by β-galactoside α2,3-sialyltransferase 4 (ST3GAL4) via substrate competition. In addition, the α2,6-sialylation is essential for Integrin β1-EGFR/LPAR4 complex formation. Altogether, our findings demonstrate ST6GAL1 is an upstream negative regulator of the Hippo pathway in breast cancer cells, providing a new insight into the regulation between N-glycosylation and Hippo signaling.

Enhancing immunogenicity and release of in situ-generated tumor vesicles for autologous vaccines

In situ vaccination (ISV) strategies offer an innovative approach to cancer immunotherapy by utilizing drug combinations directly at tumor sites to elicit personalized immune responses. Tumor cell-derived extracellular vesicles (TEVs) in ISV have great potential but face challenges such as low release rates and immunosuppressive proteins like programmed death ligand 1 (PD-L1) and CD47. This study develops a nanoparticle-based ISV strategy (Combo-NPs@shGNE) that enhances TEV release and modulates cargo composition. This approach combines Andrographolide, Icariside II, and shRNA targeting UDP-N-acetylglucosamine 2-epimerase/N-acetylmannosamine kinase (GNE), which accumulates in the tumor region, resulting in the regulation of immunosuppressive pathways and the reduction of sialic acid production. Decreasing the level of sialylation on the membrane through necroptosis and inhibition of sialic acid synthesis decreased the loading of PD-L1 and CD47 on vesicles, while increasing the loading of heat shock protein 70 and high mobility group box 1 on vesicles, and induced the release of highly immunogenic TEVs from the cancer cells, with a 56.44 % release, 9.57 times higher than that of blank nanoparticle-treated cells. In vivo studies demonstrate that Combo-NPs@shGNE enhances TEV yield, tumor growth, reduces metastases, and improves survival in an osteosarcoma mouse model. It promotes dendritic cell maturation, increases CD4+ and CD8+ T cell infiltration, and alters the microenvironment by reducing myeloid-derived suppressor cells and enhancing immunostimulatory factors. Additionally, it transitions tumor-associated macrophages from M2 to an M1 phenotype, thereby augmenting tumor immunity. Overall, Combo-NPs@shGNE offers a promising method for transforming tumors into personalized autologous vaccines, potentially advancing cancer treatment strategies.

N-glycosylation of PD-L1 modulates the efficacy of immune checkpoint blockades targeting PD-L1 and PD-1

BACKGROUND

The PD-L1/PD-1 pathway is crucial for immune regulation and has become a target in cancer immunotherapy. However, in order to improve patient selection for immune checkpoint blockade (ICB) therapies, better selection criteria are needed. This study explores how the N-glycosylation of PD-L1 affects its interaction with PD-1 and ICB efficacy, focusing on its four N-linked glycosylation sites: N35, N192, N200, and N219.

METHODS

Human PD-L1 glycosylation mutants-at each individual site or at all four sites together (Nx4)-were tested for their functional interaction with PD-1 using an artificial immune checkpoint reporter assay (IcAR-PD1). The blocking efficacy of anti-PD-L1 and anti-PD-1 antibodies was evaluated using human breast cancer cell lines (MDA-MB231 and MCF7), as well as A375 melanoma and A549 lung carcinoma cells expressing the glycosylation mutants. Results were validated through ex vivo activation and cytotoxicity assays using human CD8+ T cells.

RESULTS

The binding of the PD-L1N35A mutant to PD-1 was not effectively blocked by anti-PD-L1 and anti-PD-1 ICBs. In contrast, high blocking efficacy of PD-L1 binding to PD-1 was obtained at minimal ICB concentrations when PD-L1 did not express any glycosylation site (PD-L1Nx4 mutant). The PD-L1N35A mutant produced elevated levels of PD-L1 as a soluble (sPD-L1) and extracellular vesicles (EV)-bound molecule; in contrast, the PD-L1Nx4 mutant had lower sPD-L1 and EV levels. PD-L1 glycosylation status influenced the ability of PD-L1 interactions with PD-1 to down-regulate T-cell activation and cytotoxicity, with the PD-L1N35A mutant showing the lowest levels of T cell functions and the PD-L1Nx4 mutant the highest.

CONCLUSIONS

The N-glycosylation of PD-L1 at all four sites interferes with the ability of anti-PD-L1 and anti-PD-1 ICBs to block PD-L1 interactions with PD-1; in contrast, glycosylation at the N35 site enhances ICB blocking efficacy. These effects are connected to the ability of sPD-L1 to compete with ICB binding to PD-L1 or PD-1. Thus, assessing PD-L1 glycosylation, beyond expression levels, could improve patient stratification and outcomes.

A STT3A-dependent PD-L1 glycosylation modification mediated by GMPS drives tumor immune evasion in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a malignant tumor characterized by rapid progression. To explore the regulatory mechanism of rapid tumor growth and metastasis, we conducted proteomic and scRNA-Seq analyses on advanced HCC tissues and identified a significant molecule, guanine monophosphate synthase (GMPS), closely associated with the immune evasion in HCC. We analyzed the immune microenvironment characteristics remodeled by GMPS using scRNA-Seq and found GMPS induced tumor immune evasion in HCC by impairing the tumor-killing function of CD8 + T cells. Further investigation revealed that GMPS increased PD-L1 expression by regulating its ubiquitination and glycosylation modification. Mechanistically, GMPS enhanced the bond between PD-L1 and the catalytic subunit STT3A of oligosaccharyltransferase (OST) by acting as an additional module connecting the Sec61 channel complex and STT3A, which aided in the translocation and modification of nascent peptides. Increased PD-L1 impaired the tumor-killing function of CD8 + T cells, leading to the immune evasion. Importantly, targeting GMPS with angustmycin A, an inhibitor of GMPS activity, significantly suppressed PD-L1 expression and tumor growth in HCC, which also increased the sensitivity to anti-CTLA-4 immunotherapy. These findings suggested the potential of targeting GMPS as a promising therapeutic approach for HCC.

Novel GPC3 N-terminal bispecific antibody exhibits dual anti-tumor effect against tumor cells

Hepatocellular carcinoma (HCC) remains a leading cause of cancer-related mortality worldwide, with poor prognosis and limited treatment options, particularly in advanced stages. Glypican-3 (GPC3) has emerged as a promising therapeutic target, but existing antibodies primarily bind its C-terminal region, where glycosylation can mask epitopes and compromise efficacy. To address this limitation, we focused on the GPC3 N-terminal region, which offers better accessibility and potential for tumor signaling regulation. We developed Pro-12, a high-affinity humanized IgG1 antibody targeting the 25-45 peptide of the GPC3 N-terminus, avoiding glycosylation interference while modulating tumor pathways. Building on Pro-12, we engineered a GPC3/CD3 bispecific antibody (BsAb) using CrossMab and Knob-into-Hole technologies. This BsAb demonstrated dual anti-tumor effects by activating immune cells and inhibiting both the Wnt/β-catenin and PI3K/AKT pathways, achieving outcomes typically requiring tri-specific antibodies. Our findings highlight the GPC3 N-terminal region as a novel therapeutic target and introduce a promising bispecific antibody approach for the treatment of GPC3-positive HCC.

YAP/TEAD4/SP1-induced VISTA expression as a tumor cell-intrinsic mechanism of immunosuppression in colorectal cancer

Hyperactivation of the YAP/TEAD transcriptional complex in cancers facilitates the development of an immunosuppressive tumor microenvironment. Herein, we observed that the transcription factor SP1 physically interacts with and stabilizes the YAP/TEAD complex at regulatory genomic loci in colorectal cancer (CRC). In response to serum stimulation, PKCζ (protein kinase C ζ) was found to phosphorylate SP1 and enhance its interaction with TEAD4. As a result, SP1 enhanced the transcriptional activity of YAP/TEAD and coregulated the expression of a group of YAP/TEAD target genes. The immune checkpoint V-domain Ig suppressor of T-cell activation (VISTA) was identified as a direct target of the SP1-YAP/TEAD4 complex and found to be widely expressed in CRC cells. Importantly, YAP-induced VISTA upregulation in human CRC cells was found to strongly suppress the antitumor function of CD8+ T cells. Consistently, elevated VISTA expression was found to be correlated with hyperactivation of the SP1-YAP/TEAD axis and associated with poor prognosis of CRC patients. In addition, we found by serendipity that enzymatic deglycosylation significantly improved the anti-VISTA antibody signal intensity, resulting in more accurate detection of VISTA in clinical tumor samples. Overall, our study identified SP1 as a positive modulator of YAP/TEAD for the transcriptional regulation of VISTA and developed a protein deglycosylation strategy to better detect VISTA expression in clinical samples. These findings revealed a new tumor cell-intrinsic mechanism of YAP/TAZ-mediated cancer immune evasion.

Research progress on paternal mitochondrial inheritance: An overview

Mitochondria are self-replicating organelles with their own DNA. They play a crucial role in biological, cellular and functional processes, such as energy production, metabolism, and signal transduction. Abnormal mitochondrial function can cause various diseases such as diabetes, tumour, Parkinson's disease, hereditary optic neuropathy, and others. Although mitochondrial functions have been extensively and widely explored, studies on mitochondrial inheritance have been limited. Mitochondrial inheritance is traditionally thought to be maternal although small amounts of paternally transmitted mitochondria have been discovered on rare occasions, and the role of paternal mitochondria transmission to offspring has been largely ignored. This review highlights the present knowledge on mitochondrial inheritance, especially the controversy and the difficulties in investigating paternal mitochondrial inheritance. More significantly, we present a comprehensive description of the physiological functions of paternal mitochondria in children and discuss the animal model to explore the mechanism of paternal mitochondrial inheritance. This review may provide a theoretical and experimental basis for improving our understanding of paternal mitochondrial inheritance, and also provide new ideas for treating mitochondrial diseases.

Sugar symphony: glycosylation in cancer metabolism and stemness

Glycosylation is a complex co-translational and post-translational modification (PTM) in eukaryotes that utilizes glycosyltransferases to generate a vast array of glycoconjugate structures. Recent studies have highlighted the role of glycans in regulating essential molecular, cellular, tissue, organ, and systemic biological processes with significant implications for human diseases, particularly cancer. The metabolic reliance of cancer, spanning tumor initiation, disease progression, and resistance to therapy, necessitates a range of uniquely altered cellular metabolic pathways. In addition, the intricate interplay between cell-intrinsic and -extrinsic mechanisms is exemplified by the communication between cancer cells, cancer stem cells (CSCs), cancer-associated fibroblasts (CAFs), and immune cells within the tumor microenvironment (TME). In this review article, we explore how differential glycosylation in cancer influences the metabolism and stemness features alongside new avenues in glycobiology.

Deciphering the Metabolic Impact and Clinical Relevance of N-Glycosylation in Colorectal Cancer through Comprehensive Glycoproteomic Profiling

Colorectal cancer (CRC) progression is driven by complex metabolic alterations, including aberrant N-glycosylation patterns that critically influence tumor development. However, the metabolic and functional roles of N-glycosylation in CRC remain poorly understood. Herein, comprehensive proteomic and N-linked intact glycoproteomics analyses are performed on 45 CRC tumors, and normal adjacent tissues (NATs) are matched, identifying 7125 intact N-glycopeptides from 704 glycoproteins. Through analysis of glycoform expression profiles and structural characteristics, a glycosylation site-protein function association network is constructed to uncover metabolic dysregulation driven by N-glycosylation in CRC. Moreover, an arithmetic model is developed that integrates N-glycan expression patterns, which effectively distinguishes tumors from NATs, reflecting metabolic reprogramming in cancer. These findings identify Chloride Channel Accessory 1 (CLCA1) and Olfactomedin 4 (OLFM4) as potential metabolic biomarkers for CRC diagnosis. Immunohistochemistry and Cox regression analyses validated the prognostic power of these markers. Notably, the critical role of specific N-glycosylation at N196 of Adipocyte plasma membrane-associated protein (APMAP) is highlighted, a key player in tumor metabolism and CRC progression, providing a potential target for therapeutic intervention. These findings offer valuable insights into the metabolic roles of N-glycosylation in CRC, advancing biomarker discovery, enhancing metabolic-based diagnostic precision, and improving personalized treatment strategies targeting cancer metabolism.

Automated fast-flow synthesis of the immune checkpoint receptors PD-1 and PD-L1

Programmed cell death protein 1 (PD-1) and programmed cell death ligand 1 (PD-L1) are key targets for cancer therapy. Here, we use automated fast-flow peptide synthesis (AFPS) to rapidly produce these challenging β-sheet-rich proteins in their active forms following oxidative refolding protocols. The methods presented here provide rapid access to synthetic, air-stable mutants of PD-1 and PD-L1 in which L-methionine residues are substituted with L-norleucine, potentially enabling investigation of post-translational modifications and mirror-image analogs for drug discovery.

High-throughput capture and in situ protein analysis of extracellular vesicles by chemical probe-based array

Extracellular vesicles (EVs) are small particles with phospholipid bilayers that carry a diverse range of cargoes including nucleic acids, proteins and metabolites. EVs have important roles in various cellular processes and are increasingly recognized for their ubiquitous role in cell-cell communications and potential applications in therapeutics and diagnostics. Although many methods have been developed for the characterization and measurement of EVs, analyzing them from biofluids remains a challenge with regard to throughput and sensitivity. Recently, we introduced an approach to facilitate high-throughput analysis of EVs from trace amounts of sample. In this method, an amphiphile-dendrimer supramolecular probe (ADSP) is coated onto a nitrocellulose membrane for array-based capture and to enable an in situ immunoblotting assay. Here, we describe the protocol for our array-based method of EV profiling. We describe an enhanced version of the method that incorporates an automated printing workstation, ensuring high throughput and reproducibility. We further demonstrate the use of our array to profile specific glycosylations on the EV surface using click chemistry of an azide group introduced by metabolic labeling. In this protocol, the synthesis of ADSP and the fabrication of ADSP nitrocellulose membrane array can be completed on the same day. EVs are efficiently captured from biological or clinical samples through a 30-min incubation, followed by an immunoblotting assay within a 3-h window, thus providing a high-throughput platform for EV isolation and in situ targeted analysis of EV proteins and their modifications.

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.

An engineered PD1-Fc fusion produced in N. benthamiana plants efficiently blocks PD1/PDL1 interaction

KEY MESSAGE

Plant-made PD1-Fc fusions engineered for optimized glycosylation and Fc-receptor engagement are highly efficient in blocking PD1/PDL1 interactions and can be cost-effective alternatives to antibody-based immune checkpoint inhibitors. Immune checkpoint inhibitors (ICIs) are antibodies to receptors that have pivotal roles during T-cell activation processes. The programmed cell death 1 (PD1) can be regarded as the primary immune checkpoint and antibodies targeting PD1 or its ligand PDL1 have revolutionized immunotherapy of cancer. However, the majority of patients fail to respond, and treatment resistance as well as immune-related adverse events are commonly associated with this therapy. Alternatives to antibody-based ICIs targeting the PD1 pathway may bear the potential to overcome some of these shortcomings. Here, we have used a plant expression platform based on the tobacco relative Nicotiana benthamiana to generate immunoglobulin fusion proteins harboring the wild type or an affinity-enhanced PD1 ectodomain. We have exploited the versatility of our system to generate variants that differed regarding their glycosylation profile as well as their capability to engage Fc-receptors. Unlike its wild-type counterpart, the affinity-enhanced versions showed strongly augmented capabilities to engage PDL1 in both protein- and cell-based assays. Moreover, in contrast with clinical antibodies, their binding is not affected by the glycosylation status of PDL1. Importantly, we could demonstrate that the plant-made PD1 fusion proteins are highly efficient in blocking inhibitory PD1 signaling in a T cell reporter assay. Taken together, our study highlights the utility of our plant-based protein expression platform to generate biologics with therapeutic potential. Targeting PDL1 with plant derived affinity-enhanced PD1 immunoglobulin fusion proteins may reduce overstimulation associated with antibody-based therapies while retaining favorable features of ICIs such as long serum half-life.

Overview on biomarkers for immune oncology drugs

Although immune checkpoint inhibitors (ICIs) are widely used in clinical oncology, less than half of treated cancer patients derive benefit from this therapy. Both tumor- and host-related variables are implicated in response to ICIs. The predictive value of PD-L1 expression is confined only to several cancer types, so this molecule is not an agnostic biomarker. Highly elevated tumor mutation burden (TMB) caused either by excessive carcinogenic exposure or by a deficiency in DNA repair is a reliable indicator for ICI efficacy, as exemplified by tumors with high-level microsatellite instability (MSI-H). Other potentially relevant tumor-related characteristics include gene expression signatures, pattern of tumor infiltration by immune cells, and, perhaps, some immune-response modifying somatic mutations. Host-related factors have not yet been comprehensively considered in relevant clinical trials. Microbiome composition, markers of systemic inflammation [e.g., neutrophil-to-lymphocyte ratio (NLR)], and human leucocyte antigen (HLA) diversity may influence the efficacy of ICIs. Studies on ICI biomarkers are likely to reveal modifiable tumor or host characteristics, which can be utilized to direct the antitumor immune defense. Examples of the latter approach include tumor priming to immune therapy by cytotoxic drugs and elevation of ICI efficacy by microbiome modification.

Programmed Cell Death Ligand as a Biomarker for Response to Immunotherapy: Contribution of Mass Spectrometry-Based Analysis

Immune checkpoint inhibition is a major component in today's cancer immunotherapy. In recent years, the FDA has approved a number of immune checkpoint inhibitors (ICIs) for the treatment of melanoma, non-small-cell lung, breast and gastrointestinal cancers. These inhibitors, which target cytotoxic T-lymphocyte antigen-4, programmed cell death (PD-1), and programmed cell death ligand (PD-L1) checkpoints have assumed a leading role in immunotherapy. The same inhibitors exert significant antitumor effects by overcoming tumor cell immune evasion and reversing T-cell exhaustion. The initial impact of this therapy in cancer treatment was justly described as revolutionary, however, clinical as well as research data which followed demonstrated that these innovative drugs are costly, are associated with potentially severe adverse effects, and only benefit a small subset of patients. These limitations encouraged enhanced research and clinical efforts to identify predictive biomarkers to stratify patients who are most likely to benefit from this form of therapy. The discovery and characterization of this class of biomarkers is pivotal in guiding individualized treatment against various forms of cancer. Currently, there are three FDA-approved predictive biomarkers, however, none of which on its own can deliver a reliable and precise response to immune therapy. Present literature identifies the absence of precise predictive biomarkers and poor understanding of the mechanisms behind tumor resistance as the main obstacles facing ICIs immunotherapy. In the present text, we discuss the dual role of PD-L1 as a biomarker for response to immunotherapy and as an immune checkpoint. The contribution of mass spectrometry-based analysis, particularly the impact of protein post-translational modifications on the performance of this protein is underlined.

Regulation of PD-L1 glycosylation and advances in cancer immunotherapy

Protein glycosylation plays a versatile role in regulating homeostasis, such as cell migration, protein sorting, and the immune response. Drugs aimed at targeting glycosylation have strong implications for immunity enhancement, diagnosis, and cancer regression. Programmed death-ligand 1 (PD-L1), expressed in cancer or antigen-presenting cells, binds to programmed cell death protein 1 (PD-1) and suppresses T cells. Glycosylation of PD-L1 at N35, N192, N200, and N219 stabilizes PD-L1 on the cancer cell surface, which contributes to immune evasion by inhibiting T cell activity. To date, at least six glycosyltransferases and four associate proteins are known to regulate PD-L1 glycosylation. Terminal modifications such as poly-N-acetyl-lactosamine (poly-LacNAC), sulfation, and sialylation are commonly found on PD-L1, acting as an immune recognition ligand and regulating certain immune responses. Studies have identified many mechanisms and potential therapeutic targets within the glycosylation pathways of PD-L1, revealing their involvement in cancer pathology, immune evasion, and resistance to immunotherapy. In this review, we covered the glycoforms, terminal moiety, binding lectin, glycosyltransferase, as well as sugar analogs focusing on glycosylated PD-L1. We present a mechanism that originates from the endoplasmic reticulum (ER)-Golgi apparatus (Golgi) and its subsequent translocation to the cell membrane. This pathway determines the immune suppression function of PD-L1 and therefore regulates the immune response such as T cells, monocytes, and macrophages. This collection of findings underscores the significance of glycosylation in the role of PD-L1 in cancer and highlights multiple potential targets and strategies for improving therapeutic intervention and diagnostic techniques.

N-glycosylation of ephrin B1 modulates its function and confers therapeutic potential in B-cell lymphoma

Given the pivotal role of the Eph-Ephrin signaling pathway in tumor progression, agonists or antagonists targeting Eph-Ephrin have emerged as promising anticancer strategies. However, the implications of glycosylation modifications within Eph-Ephrin and their targeted protein therapeutics remain elusive. Here, we identify that N-glycosylation within the receptor-binding domain (RBD) of ephrin B1 (EFNB1) is indispensable for its functional repertoire. Notably, compared with wildtype EFNB1, the glycosylation-deficient N139D mutant drastically diminishes the sensitivity of tumor cells with chemotherapeutic agents, suggesting the existence of both glycosylation-dependent and -independent effects mediated by EFNB1. Transcriptomic analysis highlights immune response and oxidative phosphorylation as the primary signaling pathways modulated by glycosylation modifications. In coculture systems, the EFNB1-RBD-Fc recombinant protein, while inhibiting B-lymphoma cells, also exerts differential impacts on stromal cells depending on their glycosylation status. Furthermore, the efficacy of both glycosylated and nonglycosylated EFNB1-RBD-Fc is influenced by the endogenous EFNB1 levels within tumor cells. Taking together, this study demonstrates the complexity and multifaceted roles of glycosylation in modulating EFNB1 function. These findings underscore the need for a nuanced understanding of glycosylation patterns in Eph-Ephrin-targeted therapies to optimize their therapeutic potential.

Metabolic Singularities in Microsatellite-Stable Colorectal Cancer: Identifying Key Players in Immunosuppression to Improve the Immunotherapy Response

Although immune checkpoint inhibitor (ICI) therapy is currently the standard of care in microsatellite-unstable (MSI) metastatic colorectal cancer (CRC), ICI therapy, alone or in combination with other therapies, is not a treatment approach in microsatellite-stable (MSS) CRC, which is present in 95% of patients. In this review, we focus on metabolic singularities-at the transcriptomic (either bulk or single cell), proteomic, and post-translational modification levels-that induce immunosuppression in cancer and specifically in MSS CRC. First, we evaluate the current efficacy of ICIs in limited and metastatic disease in MSS CRC. Second, we discuss the latest findings on the potential biomarkers for evaluating ICI efficacy in MSS CRC using strict REMARK criteria. Third, we review the current evidence on metabolic patterns in CRC tumors and immune cell metabolism to advance our understanding of metabolic crosstalk and to pave the way for the development of combination strategies to enhance ICI efficacy.

Glycoscience in Advancing PD-1/PD-L1-Axis-Targeted Tumor Immunotherapy

Immune checkpoint blockade therapy, represented by anti-PD-1/PD-L1 monoclonal antibodies, has significantly changed the immunotherapy landscape. However, the treatment is still limited by unsatisfactory response rates, immune-related adverse effects, and drug resistance. Current studies have established that glycosylation, a common post-translational modification, is crucial in promoting cancer progression and immune invasion. Targeting aberrant glycosylation in cancers presents precision medicine regimens for monitoring cancer progression and developing personalized medicine. Notably, the immune checkpoints PD-1 and PD-L1 are highly glycosylated, which affects PD-1/PD-L1 interaction and the binding of anti-PD-1/PD-L1 monoclonal antibodies. Recent achievements in glycoscience to enhance patient outcomes, referred to as glycotherapy, have underscored their high potency in advancing PD-1/PD-L1 blockade therapies, i.e., glycoengineered antibodies with improved binding toward PD-1/PD-L1, pharmaceutic inhibitors for core fucosylation and sialylation, and synergistic treatment with the antibody-sialidase conjugate. This review briefly introduces the PD-1/PD-L1 axis and glycosylation and highlights the fundamental and applied advances in glycoscience that improve PD-1/PD-L1 immunoblockade therapies.

In-situ profiling of glycosylation on single cells with surface plasmon resonance imaging

Cellular glycosylation is crucial for cell recognition, signal transduction, and the development of various diseases, especially in tumor initiation, progression, and metastasis. Current glycosylation profiling methods normally involve laborious sample processing and labeling and lack in-situ quantitative analysis. Here, we present a direct optical method to investigate and quantify the glycan expression on single cells based on lectin-glycan kinetic quantification with plasmonic imaging. Three unlabeled lectins (WGA, SBA, ConA) are employed as probes to bind with specific glycans, and binding kinetics are assessed to determine glycosylation profiles. The result reveals cell-to-cell heterogeneity in glycosylation patterns. To demonstrate the capability of our method, the glycosylation profiling of four distinct cell lines is explored, showing obvious alterations in glycan expression related to tumor initiation, progression, and metastasis. This approach enables direct quantification of glycosylation and binding kinetics, providing insights into tumor cell glycosylation mechanisms and potential applications in disease diagnosis and treatment.

PD-L1 expression in multiple myeloma myeloid derived suppressor cells

The Programmed Cell Death Protein 1/Programmed Cell Death Protein Ligand 1 (PD-1/PD-L1) axis stands as one of the most widely acknowledged targets for cancer immunotherapy. This ligand is considered a therapeutic target for this disease as it might play an important role in tumor immune evasion and drug resistance. In multiple myeloma (MM), PD-L1 is overexpressed in abnormal plasma cells and Myeloid-Derived Suppressor Cells (MDSCs). In MDSCs, unlike tumoral cells or derived cell lines, the PD-L1 protein is presented in a conformation not recognized by the monoclonal antibody. In contrast, when stimulating the sample with PMA, the PD-L1 molecule undergoes a conformational change that enables its recognition. Hence, we have developed a flow cytometric screening assay to determine PD-L1 conformational changes in MDSCs based on a minimal manipulation of the sample, to preserve the structure and functionality of the ligand. In this chapter, we provide detailed protocols to assess PD-L1 levels in MDSCs together with the representative results obtained in multiple myeloma patients. The obtained results enable the classification of MM patients based on the different PD-L1 detection after stimulation, which increases compared with unstimulated samples. We also provide protocols to assess kinetic analysis of PD-L1 expression over time and to compare PD-L1 cell surface expression with cytoplasmic expression. Finally, competitive experiments in the presence of durvalumab are also described to study its interaction with PD-L1. This approach can also be used to study the contribution of potential conformational changes in other proteins.

Advancing precision cancer immunotherapy drug development, administration, and response prediction with AI-enabled Raman spectroscopy

Molecular characterization of tumors is essential to identify predictive biomarkers that inform treatment decisions and improve precision immunotherapy development and administration. However, challenges such as the heterogeneity of tumors and patient responses, limited efficacy of current biomarkers, and the predominant reliance on single-omics data, have hindered advances in accurately predicting treatment outcomes. Standard therapy generally applies a "one size fits all" approach, which not only provides ineffective or limited responses, but also an increased risk of off-target toxicities and acceleration of resistance mechanisms or adverse effects. As the development of emerging multi- and spatial-omics platforms continues to evolve, an effective tumor assessment platform providing utility in a clinical setting should i) enable high-throughput and robust screening in a variety of biological matrices, ii) provide in-depth information resolved with single to subcellular precision, and iii) improve accessibility in economical point-of-care settings. In this perspective, we explore the application of label-free Raman spectroscopy as a tumor profiling tool for precision immunotherapy. We examine how Raman spectroscopy's non-invasive, label-free approach can deepen our understanding of intricate inter- and intra-cellular interactions within the tumor-immune microenvironment. Furthermore, we discuss the analytical advances in Raman spectroscopy, highlighting its evolution to be utilized as a single "Raman-omics" approach. Lastly, we highlight the translational potential of Raman for its integration in clinical practice for safe and precise patient-centric immunotherapy.

Expression of ALG8 in hepatocellular carcinoma and its diagnostic and prognostic significance

BACKGROUND

Alpha-1,3-glucosyltransferase (ALG8), a key enzyme in protein glycosylation, is implicated in the oncogenesis and progression of several human malignancies. This study aimed to define the role of ALG8 in hepatocellular carcinoma (HCC) and uncover its mechanisms of action.

METHODS

ALG8 expression in HCC and normal tissues was analyzed using the TCGA and GEO databases, validated by RT-qPCR and western blot. Survival outcomes were evaluated via Cox analyses, and ALG8's impact on HCC behavior was examined through functional assays. GO, KEGG, and GSEA identified ALG8-related pathways, validated by biochemical assays.

RESULTS

In bioinformatics analyses, ALG8 was overexpressed in HCC tissues (p < 0.05 for all comparisons) and correlated with poorer survival (p = 0.006 and p = 0.025, respectively), establishing its role as an independent prognostic factor. In vitro experiments showed that knockdown of ALG8 reduced HCC cell proliferation, migration, and invasion. Using the STRING platform and TCGA-LIHC dataset, we identified ALG8-interacting genes and their associated differentially expressed genes (DEGs). GO and KEGG analyses further linked ALG8 to genes involved in glycosylation, signal release, and other processes, as well as pathways including neuroactive ligand-receptor interaction and N-Glycan biosynthesis. GSEA, corroborated by western blot and immunofluorescence, points to the Wnt/β-catenin signaling cascade as a probable mechanistic pathway through which ALG8 may modulate HCC progression.

CONCLUSION

Elevated ALG8 expression in HCC is linked to worse outcomes and increased tumor aggressiveness, with silencing ALG8 reducing Wnt/β-catenin signaling, highlighting ALG8 as a potential therapeutic target.

Disrupting EDEM3-induced M2-like macrophage trafficking by glucose restriction overcomes resistance to PD-1/PD-L1 blockade

BACKGROUND

Immunotherapy is beneficial for some colorectal cancer (CRC) patients, but immunosuppressive networks limit its effectiveness. Cancer-associatedfibroblasts (CAFs) are significant in immune escape and resistance toimmunotherapy, emphasizing the urgent need for new treatment strategies.

METHODS

Flow cytometric, Western blotting, proteomics analysis, analysis of public database data, genetically modified cell line models, T cell coculture, crystal violetstaining, ELISA, metabonomic and clinical tumour samples were conducted to assess the role of EDEM3 in immune escape and itsmolecular mechanisms. We evaluated theeffects of FMD plus 2-DG on antitumour immunity using multipleximmunofluorescence, flow cytometry, cytokine profiling, TUNEL assays, xenografttumours, and in vivo studies.

RESULTS

We show thatCAFs upregulate PD-L1 glycosylation and contribute to immune evasion byglycosyltransferase EDEM3. Additionally, EDEM3 plays a role in tumour immunityduring tumour progression. However, the EDEM3-mediated upregulation of PD-L1 expression underpins PD-1/PD-L1 blockade resistance in vivo. This finding contradictsthe previous trend that positive PD-L1 expression indicates a strong responseto PD-1/PD-L1 blockade. Mechanistically, high-EDEM3 expression facilitates M2-like This finding contradictsthe previous trend that positive PD-L1 expression indicates a strong responseto PD-1/PD-L1 blockade.Mechanistically, polarizationand chemotactic migration of macrophages, which are enriched in theperipheral region of tumours compared to thecore region, precluding access of CD8+ T cells to tumourfoci. Furthermore, we EDEM3 predominantly activates the recruited M2-like macrophagesvia a glucose metabolism-dependent mechanism. Manipulationof glucose utilization by a fasting-mimicking diet(FMD) plus 2-DG treatmentsynergistically with PD-1 antibody elicits potent antitumour activity byeffectively decreasing tumour glycosylated PD-L1 expression, augmenting the CD8+effector T cell infiltration and activation while concurrently reducing the infiltration.TheCAFs-EDEM3-M2-like macrophage axis plays a critical role in promotingimmunotherapy resistance. infiltration.TheCAFs-EDEM3-M2-like macrophage axis plays a critical role in promotingimmunotherapy resistance.

CONCLUSIONS

Our study suggests that blocking EDEM3-induced M2-like macro phage trafficking by FMD plus 2-DG is a promising and effective strategy to overcomeresistance to checkpoint blockade therapy offeringhope for improved treatment outcomes.

KEY POINTS

Cancer-associated fibroblasts (CAFs) can enhance PD-L1 glycosylation through the glycosyltransferase EDEM3, contributing to immune evasion during tumour progression. EDEM3 predominantly activates the recruit M2-like macrophages via a glucose metabolism-dependent mechanism. Blocking glucose utilization antagonizes recruiting and polarizing M2-like macrophages synergistically with PD-1 antibody to improve anticancer immunity.

Predicting response to PD-1 inhibitors in head and neck squamous cell carcinomas using peripheral blood inflammatory markers

Immune checkpoint inhibitor (ICI) treatment has the potential to induce durable disease remission. However, the current combined positive score (CPS) is insufficient accurate for predicting which patients will benefit from it. In the present study, a real-world retrospective study was conducted on 56 patients of HNSCC who received ICI treatment. Then the treatment that patient received and levels of pre-treatment blood inflammatory markers (NLR, MLR and PLR) were identified to develop a model for predicting immunotherapy response. Notably, the model achieved an area under the curve (AUC) of 0.877 (95 % CI 0.769-0.985) , providing a larger net benefit than the CPS marker (AUC=0.614, 95 % CI 0.466-0.762). Furthermore, the internal validation of the prediction model showed a C-index of 0.835. Patients with high score of the model would get improved PFS than those with low score. Therefore, the prediction model for patients with local advanced or R/M HNSCC receiving ICI treatment, which represented an better efficient prediction of immunotherapy response than CPS marker.

MAN2B1 in immune system-related diseases, neurodegenerative disorders and cancers: functions beyond α-mannosidosis

Glycosylation modifications of proteins and glycan hydrolysis are critical for protein function in biological processes. Aberrations in glycosylation enzymes are linked to lysosomal storage disorders (LSDs), immune interactions, congenital disorders and tumour progression. Mannosidase alpha class 2B member 1 (MAN2B1) is a lysosomal hydrolase from the α-mannosidase family. Dysfunction of MAN2B1 has been implicated as causative factors in mannosidosis, a lysosomal storage disorder characterised by cognitive impairment, hearing loss and immune system and skeletal anomalies. Despite decades of research, its role in pathogenic infections, autoimmune conditions, cancers and neurodegenerative pathologies is highly ambiguous. Future studies are required to shed more light on the intricate functioning of MAN2B1. To this end, we review the biological functions, expression patterns, enzymatic roles and potential implications of MAN2B1 across various cell types and disease contexts. Additionally, the novel insights presented in this review may aid in understanding the role of MAN2B1 in immune cells, thereby paving the way for targeted therapeutic interventions in immune-related disorders.

MGAT4A/Galectin9-Driven N-Glycosylation Aberration as a Promoting Mechanism for Poor Prognosis of Endometrial Cancer with TP53 Mutation

Emerging evidence recognizes aberrant glycosylation as the malignant characteristics of cancer cells, but little is known about glycogenes' roles in endometrial carcinoma (EC), especially the most aggressive subtype carrying TP53 mutations. Using unsupervised hierarchical clustering, an 11-glycogene cluster is identified to distinguish an EC subtype associated with frequent TP53 mutation and worse prognosis. Among them, MGAT4A (alpha-1,3-mannosyl-glycoprotein 4-β-N-acetylglucosaminyltransferase A) emerges as the most consistently overexpressed glycogene, contributing to EC aggressiveness. In the presence of galectin-9, MGAT4A increases EC cell proliferation and invasion via promoting glucose metabolism. N-glycoproteomics further revealed GLUT1, a glucose transporter, as a glycoprotein modified by MGAT4A. Binding of galectin-9 to the MGAT4A-branched N-glycan on GLUT1 enhances its cell membrane distribution, leading to glucose uptake increase. In addition, oncogenic mutations of TP53 gene in EC cells upregulate MGAT4A expression by disrupting the regulatory oversight exerted by wild-type p53 on tumor-suppressive miRNAs, including miR-34a and miR-449a/b. The findings highlight a new molecular mechanism involving MGAT4A-regulated N-glycosylation on the key regulator of glucose metabolism in p53 mutants-driven EC aggressiveness, which may provide a strategic avenue to combat advanced EC.

CAR T cells in solid tumors and metastasis: paving the way forward

CAR T cell therapy, hailed as a breakthrough in cancer treatment due to its remarkable outcomes in hematological malignancies, encounters significant hurdles when applied to solid tumors. While notable responses to CAR T cells remain sporadic in these patients, challenges persist due to issues such as on-target off-tumor toxicity, difficulties in their trafficking and infiltration into the tumor, and the presence of a hostile and immunosuppressive microenvironment. This review aims to explore recent endeavors aimed at overcoming these obstacles in CAR T cell therapy for solid tumors. Specifically, we will delve into promising strategies for enhancing tumor specificity through antigen targeting, addressing tumor heterogeneity, overcoming physical barriers, and counteracting the immune-suppressive microenvironment.

Sugar Highs: Recent Notable Breakthroughs in Glycobiology

Glycosylation is biochemically complex and functionally critical to a wide range of processes and disease states, making it a vibrant area of contemporary research. Here, we highlight a selection of notable recent advances in the glycobiology of SARS-CoV-2 infection and immunity, cancer biology and immunotherapy, and newly discovered glycosylated RNAs. Together, these studies illustrate the significance of glycosylation in normal biology and the great promise of manipulating glycosylation for therapeutic benefit in disease.

Tumor-specific delivery of clickable inhibitor for PD-L1 degradation and mitigating resistance of radioimmunotherapy

Achieving selective and durable inhibition of programmed death ligand 1 (PD-L1) in tumors for T cell activation remains a major challenge in immune checkpoint blockade therapy. We herein presented a set of clickable inhibitors for spatially confined PD-L1 degradation and radioimmunotherapy of cancer. Using metabolic glycan engineering click bioorthogonal chemistry, PD-L1 expressed on tumor cell membranes was labeled with highly active azide groups. This enables covalently binding of the clickable inhibitor with PD-L1 and subsequent PD-L1 degradation. A pH-activatable nanoparticle responding to extracellular acidic pH of tumor was subsequently used to deliver the clickable PD-L1 inhibitor into extracellular tumor microenvironment for depleting PD-L1 on the surface of tumor cell and macrophage membranes in vivo. We further demonstrated that a combination of the clickable PD-L1 inhibitor with radiotherapy (RT) eradicated the established tumor by inhibiting RT-up-regulated PD-L1 in the tumor tissue. Therefore, selective PD-L1 blockade in tumors via the clickable PD-L1 inhibitor offers a versatile approach to promote cancer immunotherapy.

Nuclear PD-L1 compartmentalization suppresses tumorigenesis and overcomes immunocheckpoint therapy resistance in mice via histone macroH2A1

Canonically PD-L1 functions as the inhibitory immune checkpoint on cell surface. Recent studies have observed PD-L1 expression in the nucleus of cancer cells. But the biological function of nuclear PD-L1 (nPD-L1) in tumor growth and antitumor immunity is unclear. Here we enforced nPD-L1 expression and established stable cells. nPD-L1 suppressed tumorigenesis and aggressiveness in vitro and in vivo. Compared with PD-L1 deletion, nPD-L1 expression repressed tumor growth and improved survival more markedly in immunocompetent mice. Phosphorylated AMPKα (p-AMPKα) facilitated nuclear PD-L1 compartmentalization and then cooperated with it to directly phosphorylate S146 of histone variant macroH2A1 (mH2A1) to epigenetically activate expression of genes of cellular senescence, JAK/STAT, and Hippo signaling pathways. Lipoic acid (LA) that induced nuclear PD-L1 translocation suppressed tumorigenesis and boosted antitumor immunity. Importantly, LA treatment synergized with PD-1 antibody and overcame immune checkpoint blockade (ICB) resistance, which likely resulted from nPD-L1-increased MHC-I expression and sensitivity of tumor cells to interferon-γ. These findings offer a conceptual advance for PD-L1 function and suggest LA as a promising therapeutic option for overcoming ICB resistance.

Use of 3' Rapid Amplification of cDNA Ends (3' RACE)-Based Targeted RNA Sequencing for Profiling of Druggable Genetic Alterations in Urothelial Carcinomas

Targeted treatment of advanced or metastatic urothelial carcinomas (UCs) requires the identification of druggable mutations. This study describes the development of a 3' Rapid Amplification of cDNA Ends (3' RACE)-based targeted RNA sequencing panel which accounts for the status of all genes relevant to UC treatment, namely, FGFR1-4, KRAS, NRAS, BRAF, ERBB2 (HER2), CD274 (PD-L1) and PIK3CA. FGFR2/3-activating point mutations or fusions were found in 54/233 (23.2%) tumors. FGFR3 rearrangements were identified in 11 patients, with eight of them being undetectable by commonly used PCR kits. In addition, one tumor contained a high-copy FGFR2 gene amplification accompanied by strong overexpression of the gene. Mutations in RAS/RAF genes were present in 30/233 (12.9%) UCs and were mutually exclusive with alterations affecting FGFR2/3 genes. On the contrary, activating events in the HER2 oncogene (point mutations and overexpression), as well as PIK3CA mutations, which were relatively common, occurred with similar frequencies in RAS/RAF- or FGFR2/3-positive vs. negative samples. High PD-L1 mRNA expression was associated with advanced disease stage and was not observed in tumors with increased HER2 mRNA expression or in UCs with evidence for FGFR2/3 activation. Three of the studied carcinomas had high-level microsatellite instability (MSI). Overall, more than half of the UCs had potentially druggable genetic alterations. The proposed NGS panel permits comprehensive and cost-efficient analysis of UC-specific molecular targets and may be considered in clinical routine.

TMED inhibition suppresses cell surface PD-1 expression and overcomes T cell dysfunction

BACKGROUND

Blockade of the programmed cell death protein 1 (PD-1) immune checkpoint (ICB) is revolutionizing cancer therapy, but little is known about the mechanisms governing its expression on CD8 T cells. Because PD-1 is induced during activation of T cells, we set out to uncover regulators whose inhibition suppresses PD-1 abundance without adversely impacting on T cell activation.

METHODS

To identify PD-1 regulators in an unbiased fashion, we performed a whole-genome, fluorescence-activated cell sorting (FACS)-based CRISPR-Cas9 screen in primary murine CD8 T cells. A dual-readout design using the activation marker CD137 allowed us to uncouple genes involved in PD-1 regulation from those governing general T cell activation.

RESULTS

We found that the inactivation of one of several members of the TMED/EMP24/GP25L/p24 family of transport proteins, most prominently TMED10, reduced PD-1 cell surface abundance, thereby augmenting T cell activity. Another client protein was cytotoxic T lymphocyte-associated protein 4 (CTLA-4), which was also suppressed by TMED inactivation. Treatment with TMED inhibitor AGN192403 led to lysosomal degradation of the TMED-PD-1 complex and reduced PD-1 abundance in tumor-infiltrating CD8 T cells (TIL) in mice, thus reversing T cell dysfunction. Clinically corroborating these findings, single-cell RNA analyses revealed a positive correlation between TMED expression in CD8 TIL, and both a T cell dysfunction signature and lack of ICB response. Similarly, patients receiving a TIL product with high TMED expression had a shorter overall survival.

CONCLUSION

Our results uncover a novel mechanism of PD-1 regulation, and identify a pharmacologically tractable target whose inhibition suppresses PD-1 abundance and T cell dysfunction.

CAR-T cell therapy for hepatocellular carcinoma: current trends and challenges

Hepatocellular carcinoma (HCC) ranks among the most prevalent cancers worldwide, highlighting the urgent need for improved diagnostic and therapeutic methodologies. The standard treatment regimen generally involves surgical intervention followed by systemic therapies; however, the median survival rates for patients remain unsatisfactory. Chimeric antigen receptor (CAR) T-cell therapy has emerged as a pivotal advancement in cancer treatment. Both clinical and preclinical studies emphasize the notable efficacy of CAR T cells in targeting HCC. Various molecules, such as GPC3, c-Met, and NKG2D, show significant promise as potential immunotherapeutic targets in liver cancer. Despite this, employing CAR T cells to treat solid tumors like HCC poses considerable challenges within the discipline. Numerous innovations have significant potential to enhance the efficacy of CAR T-cell therapy for HCC, including improvements in T cell trafficking, strategies to counteract the immunosuppressive tumor microenvironment, and enhanced safety protocols. Ongoing efforts to discover therapeutic targets for CAR T cells highlight the need for the development of more practical manufacturing strategies for CAR-modified cells. This review synthesizes recent findings and clinical advancements in the use of CAR T-cell therapies for HCC treatment. We elucidate the therapeutic benefits of CAR T cells in HCC and identify the primary barriers to their broader application. Our analysis aims to provide a comprehensive overview of the current status and future prospects of CAR T-cell immunotherapy for HCC.

ALG3 predicts poor prognosis and increases resistance to anti-PD-1 therapy through modulating PD-L1 N-link glycosylation in TNBC

OBJECTIVE

The aim of this study was to assess the prognostic significance of α-1,3-mannitrotransferase (ALG3) in triple-negative breast cancer (TNBC) and investigate its impact and potential mechanism on the efficacy of anti-PD-1 therapy.

METHODS

Bioinformatics analysis was used to examine the expression of ALG3 in cancer patients using UACLAN and other databases. The associations of the ALG3 gene and the clinicopathological features of breast cancer were examined with bc-GenExMiner database. Correlation between ALG3 expression and survival was further established utilizing the Kaplan-Meier Plotter database. Immunohistochemistry (IHC) was used to analyze the expression of ALG3 in cohort of breast cancer patients from Hubei cancer hospital to confirmed the prognostic value of ALG3 in TNBC. The effect of ALG3 on the levels of infiltrating immune cells was also analyzed. And the mutation module within cBioPortal was utilized to visualize ALG3 mutations in BRCA. The CRISPR/Cas9 technique was used to establish ALG3 low-expression TNBC cell lines. Influence of ALG3 expression on cancer cell proliferation and chemotherapeutic responsiveness was scrutinized in vitro. Animal models were constructed to evaluate the alteration of tumor sensitivity to anti-PD-1 therapy with decreased ALG3 expression. And flow cytometry and IHC were used to investigate the tumor immune microenvironment. Association of PD-L1 Glycosylation and ALG3 expression were also investigated by western blot.

RESULTS

ALG3 expression was elevated in TNBC and was strikingly linked to unfavorable clinical features such as lymphatic node metastasis, high NPI, advanced stage and age, etc. Furthermore, high ALG3 expression was associated with shorter OS in TNBC patients. Mechanistically, ALG3 expression was negatively correlated with the infiltration of CD8+ T cells, CD4+ T cells, and NK cells. ALG3-KO cells had increased sensitivity to chemotherapeutic agents. In animal models, the volume of ALG3-KO tumors was lower than the control group with immunotherapy. ALG3-KO tumors showed an increased proportion of CD8+ T cells, while a decreased proportion of regulatory T cells and M2-type macrophages. The expression level of PD-L1 protein was not affected by ALG3 level, but the glycosylation level was significantly decreased in tumor. Similarly, the glycosylation level of PD-L1 is reduced in ALG3-KO cell in vitro. Additionally, ALG3 knockout lead to reduced tolerance of tumor cells to IFN-γ, thereby enhancing the efficacy of immunotherapy.

CONCLUSION

ALG3 is a potential biomarker for poor prognosis of TNBC and may reduce the efficacy of immunotherapy by modulating the tumor microenvironment and glycosylation of PD-L1.

All-trans retinoic acid-mediated ADAR1 degradation synergizes with PD-1 blockade to suppress pancreatic cancer

As a double-stranded RNA-editing enzyme and an interferon-stimulated gene, double-stranded RNA-specific adenosine deaminase (ADAR1) suppresses interferon signaling and contributes to immunotherapy resistance. Suppression of ADAR1 overcomes immunotherapy resistance in preclinical models, but has not yet been translated to clinical settings. By conducting a screening of a subset of the FDA-approved drugs, we found that all-trans retinoic acid (ATRA, also known as tretinoin) caused ADAR1 protein degradation through ubiquitin-proteasome pathways and concomitantly increased PD-L1 expression in pancreatic and breast cancers. In addition, the combination of ATRA and PD-1 blockade reprogrammed the tumor microenvironment and unleashed antitumor immunity and thereby impeded tumor growth in pancreatic cancer mouse models. In a pilot clinical trial, a higher dose of ATRA plus the anti-PD-1 antibody nivolumab prolonged median overall survival in patients with chemotherapy-resistant pancreatic cancer compared to a lower dose of the same regimen. In this study, ATRA was the first drug to be found to cause ADAR1 degradation. We propose translation of a promising 2-pronged antitumor strategy using ATRA and nivolumab to convert immunologically "cold" into "hot" tumors susceptible to immune checkpoint blockade.

Delineating the Immunotherapeutic Potential of Vitamin E and Its Analogues in Cancer: A Comprehensive Narrative Review

Cancer is a disease resulting from uncontrolled cell division, which significantly contributes to human mortality rates. An alternative approach to cancer treatment, such as cancer immunotherapy, is needed as the existing chemotherapy and radiotherapy approaches target the cancer cells and healthy dividing cells. Vitamin E is a plant-derived lipid-soluble antioxidant with numerous health-promoting benefits, including anticancer and immunomodulatory properties. Vitamin E comprises eight natural isoforms: tocopherols (α, β, δ, and γ) and tocotrienols (α, β, δ, and γ). While initial research focused on the anticancer properties of α-tocopherol, there is growing interest in other natural forms and modified synthetic analogues of vitamin E due to their unique properties and enhanced anticancer effects. Hence, this review is aimed at outlining the effect of vitamin E and its analogues at various steps of the cancer-immunity cycle that can be used to stimulate anticancer immune responses.

A functional role for glycosylated B7-H5/VISTA immune checkpoint protein in metastatic clear cell renal cell carcinoma

Increased expression of the B7 family of immune checkpoint proteins hinders tumor elimination by the immune system. Expression levels of the B7-H5 protein were found to be upregulated in clear cell renal cell carcinomas (ccRCC). We here report the molecular, functional, and clinical characterization of B7-H5 from renal cancer cells and metastatic ccRCC tumors. B7-H5 was highly glycosylated and mainly expressed in the cell membrane. Mutagenic studies on B7-H5 identified the residues targeted by N-glycosylation and revealed an impact of B7-H5 glycosylation on protein expression levels and localization. B7-H5 knockdown decreased the cell proliferation and viability of renal cancer cells. We analyzed B7-H5 expression on tumor cells and tumor-infiltrated leukocytes (TILs) in samples from metastatic ccRCC patients and found that B7-H5 expression on TILs correlated with syncronous metastases and poor outcomes. These results provide insights into the molecular properties and clinical impact of B7-H5 and support B7-H5 as a new immunotherapeutic target in metastatic ccRCC.

New horizons in the mechanisms and therapeutic strategies for PD-L1 protein degradation in cancer

Programmed death-ligand 1 (PD-L1) has become a crucial focus in cancer immunotherapy considering it is found in many different cells. Cancer cells enhance the suppressive impact of programmed death receptor 1 (PD-1) through elevating PD-L1 expression, which allows them to escape immune detection. Although there have been significant improvements, the effectiveness of anti-PD-1/PD-L1 treatment is still limited to a specific group of patients. An important advancement in cancer immunotherapy involves improving the PD-L1 protein degradation. This review thoroughly examined the processes by which PD-L1 breaks down, including the intracellular pathways of ubiquitination-proteasome and autophagy-lysosome. In addition, the analysis revealed changes that affect PD-L1 stability, such as phosphorylation and glycosylation. The significant consequences of these procedures on cancer immunotherapy and their potential role in innovative therapeutic approaches are emphasised. Our future efforts will focus on understanding new ways in which PD-L1 degradation is controlled and developing innovative treatments, such as proteolysis-targeting chimeras designed specifically to degrade PD-L1. It is crucial to have a thorough comprehension of these pathways in order to improve cancer immunotherapy strategies and hopefully improve therapeutic effectiveness.

Glycans in melanoma: Drivers of tumour progression but sweet targets to exploit for immunotherapy

Aberrant glycosylation recently emerged as an unmissable hallmark of cancer progression in many cancers. In melanoma, there is growing evidence that the tumour 'glycocode' plays a major role in promoting cell proliferation, invasion, migration, but also dictates the nature of the immune infiltrate, which strongly affects immune cell function, and clinical outcome. Aberrant glycosylation patterns dismantle anti-tumour defence through interactions with lectins on immune cells, which are crucial to shape anti-tumour immunity but also to trigger immune evasion. The glycan/lectin axis represents a new immune subversion pathway that is exploited by melanoma to hijack immune cells and escape from immune control. In this review, we describe the glycosylation features of melanoma tumour cells, and further gather findings related to the role of glycosylation in melanoma tumour progression, deciphering in detail its impact on immunity. We also depict glycan-based strategies aiming at restoring a functional anti-tumour response in melanoma patients. Glycans/lectins emerge as key immune checkpoints with promising translational properties. Exploitation of these pathways could reshape potent anti-tumour immunity while impeding immunosuppressive circuits triggered by aberrant tumour glycosylation patterns, holding great promise for cancer therapy.

In Situ Engineering Cancer Mask to Immobilize Tumor Cells and Block Metastasis

This work reports a new concept of cancer mask in situ to alter the specific biological functions of cancer cells. Metastatic cancer cells are highly invasive in part due to the presence of the glycan matrix in the cell membrane. Using a rational designed bio-orthogonal reaction, the cancer cell surface is reconstructed in situ by incorporating endogenous polysialic acids in the glycan matrix on the cell membrane to form a mesh-like network, called cancer mask. The network of the glycan matrix can not only immobilize cancer cells but also effectively block the stimulation of metastasis promoters to tumor cells and inhibit the formation of epithelial to mesenchymal transition (EMT), causing metastatic cancer cells incarceration. The results demonstrate a new strategy to control and even eliminate the cancer metastasis that is a major cause of treatment failure and poor patient outcome.

Ginsenoside Rg3 targets glycosylation of PD-L1 to enhance anti-tumor immunity in non-small cell lung cancer

Background

Reactivate the T cell immunity by PD-1/PD-L1 checkpoint blockade is widely used in non-small cell lung cancer (NSCLC) patients, while the post-translational modification of Programmed death ligand-1 (PD-L1) is commonly existed in various cancer cells, thus increases the complexity and difficulty in therapy development. Ginsenoside Rg3 is an active component of traditional Chinese herb Ginseng with multiple pharmacological effects including immune regulation. However, the effect on the glycosylation of PD-L1 is unknown.

Methods

NSCLC cell lines were tested for glycosylation of PD-L1, and the potential mechanisms were investigated. Tumor cell-T cell coculture experiment was conducted and the activation of T cells and cytotoxicity were measured by flow cytometry. In vivo xenograft mouse tumor model was used to investigate the effects of Rg3 on PD-L1-mediated immunosuppression and tumor growth.

Results

Here, we identified PD-L1 is widely N-linked glycosylated in NSCLC cell lines, while Rg3 could inhibit the glycosylation of PD-L1 by downregulating the EGFR signaling and further activate GSK3b-mediated degradation, thus resulted in reduced PD-L1 expression. Moreover, the inhibition of PD-L1 glycosylation promoted the activation and cytotoxicity of T cells under coculture condition. In addition, Rg3 could decrease the tumor volume and enhance anti-tumor T cell immunity as evidence by the upregulated expression of Granzyme B and perforin in CD8+T cells, along with elevated serum IL-2, IFN-g and TNF-a level in Rg3-treated mice.

Conclusions

These results suggest that Rg3 inhibits PD-L1 glycosylation and thus enhance anti-tumor immunity, which provide new therapeutic insight into drug discovery.

Glycosylation: mechanisms, biological functions and clinical implications

Protein post-translational modification (PTM) is a covalent process that occurs in proteins during or after translation through the addition or removal of one or more functional groups, and has a profound effect on protein function. Glycosylation is one of the most common PTMs, in which polysaccharides are transferred to specific amino acid residues in proteins by glycosyltransferases. A growing body of evidence suggests that glycosylation is essential for the unfolding of various functional activities in organisms, such as playing a key role in the regulation of protein function, cell adhesion and immune escape. Aberrant glycosylation is also closely associated with the development of various diseases. Abnormal glycosylation patterns are closely linked to the emergence of various health conditions, including cancer, inflammation, autoimmune disorders, and several other diseases. However, the underlying composition and structure of the glycosylated residues have not been determined. It is imperative to fully understand the internal structure and differential expression of glycosylation, and to incorporate advanced detection technologies to keep the knowledge advancing. Investigations on the clinical applications of glycosylation focused on sensitive and promising biomarkers, development of more effective small molecule targeted drugs and emerging vaccines. These studies provide a new area for novel therapeutic strategies based on glycosylation.

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.

Current status and progress of PD-L1 detection: guiding immunotherapy for non-small cell lung cancer

Non-small cell lung cancer (NSCLC) is the leading cause of cancer-related deaths and represents a substantial disease burden worldwide. Immune checkpoint inhibitors combined with chemotherapy are the standard first-line therapy for advanced NSCLC without driver mutations. Programmed death-ligand 1 (PD-L1) is currently the only approved immunotherapy marker. PD-L1 detection methods are diverse and have developed rapidly in recent years, such as improved immunohistochemical detection methods, the application of liquid biopsy in PD-L1 detection, genetic testing, radionuclide imaging, and the use of machine learning methods to construct PD-L1 prediction models. This review focuses on the detection methods and challenges of PD-L1 from different sources, and discusses the influencing factors of PD-L1 detection and the value of combined biomarkers. Provide support for clinical screening of immunotherapy-advantage groups and formulation of personalized treatment decisions.

Advances and prospects of biomarkers for immune checkpoint inhibitors

Immune checkpoint inhibitors (ICIs) activate anti-cancer immunity by blocking T cell checkpoint molecules such as programmed death 1 (PD-1) and cytotoxic T lymphocyte-associated protein 4 (CTLA-4). Although ICIs induce some durable responses in various cancer patients, they also have disadvantages, including low response rates, the potential for severe side effects, and high treatment costs. Therefore, selection of patients who can benefit from ICI treatment is critical, and identification of biomarkers is essential to improve the efficiency of ICIs. In this review, we provide updated information on established predictive biomarkers (tumor programmed death-ligand 1 [PD-L1] expression, DNA mismatch repair deficiency, microsatellite instability high, and tumor mutational burden) and potential biomarkers currently under investigation such as tumor-infiltrated and peripheral lymphocytes, gut microbiome, and signaling pathways related to DNA damage and antigen presentation. In particular, this review aims to summarize the current knowledge of biomarkers, discuss issues, and further explore future biomarkers.

PD-L1 promotes oncolytic virus infection via a metabolic shift that inhibits the type I IFN pathway

While conventional wisdom initially postulated that PD-L1 serves as the inert ligand for PD-1, an emerging body of literature suggests that PD-L1 has cell-intrinsic functions in immune and cancer cells. In line with these studies, here we show that engagement of PD-L1 via cellular ligands or agonistic antibodies, including those used in the clinic, potently inhibits the type I interferon pathway in cancer cells. Hampered type I interferon responses in PD-L1-expressing cancer cells resulted in enhanced efficacy of oncolytic viruses in vitro and in vivo. Consistently, PD-L1 expression marked tumor explants from cancer patients that were best infected by oncolytic viruses. Mechanistically, PD-L1 promoted a metabolic shift characterized by enhanced glycolysis rate that resulted in increased lactate production. In turn, lactate inhibited type I IFN responses. In addition to adding mechanistic insight into PD-L1 intrinsic function, our results will also help guide the numerous ongoing efforts to combine PD-L1 antibodies with oncolytic virotherapy in clinical trials.

Discordant PD-L1 results between 28-8 and 22C3 assays are associated with outcomes of gastric cancer patients treated with nivolumab plus chemotherapy

BACKGROUND

We evaluated the concordance/discordance of PD-L1 staining results between the 28-8 and 22C3 assays and its impact on the efficacy outcomes of advanced gastric cancer patients treated with nivolumab plus chemotherapy.

METHODS

This retrospective study involved 143 gastric cancer patients treated with first-line nivolumab plus chemotherapy whose PD-L1 results with both 28-8 and 22C3 assays were available. The concordance/discordance between these assays and the inter-observer variability were evaluated for PD-L1 combined positive score (CPS) positivity. Discordant PD-L1 results were analyzed regarding survival outcomes.

RESULTS

The agreement rates and Cohen's kappa values between the 28-8 and 22C3 assays were 78.3% and 0.56 (for CPS ≥ 1), 81.8% and 0.60 (for CPS ≥ 5), and 88.8% and 0.66 (for CPS ≥ 10), respectively. Inter-observer variability, as represented by the intra-class correlation coefficient, was 0.89 and 0.88 for the 28-8 and 22C3 assays, respectively. With PD-L1 CPS ≥ 5 defined as positive, 35 (24.5%) and 82 (57.3%) had concordantly positive and negative results, respectively, between the 28-8 and 22C3 assays, whereas 26 (18.2%) had discordant results. Progression-free survival was shorter for those who exhibited negatively concordant PD-L1 results and discordant PD-L1 positivity between the 28-8 and 22C3 assays relative to those with positively concordant PD-L1 results (P = 0.013).

CONCLUSION

PD-L1 assays by 28-8 and 22C3 showed suboptimal concordance, while inter-observer variability was not critical in advanced gastric cancer. Discordant PD-L1 results between 28-8 and 22C3 assays may be associated with unfavorable efficacy outcomes in patients treated with nivolumab plus chemotherapy.