Galectin-9 promotes a suppressive microenvironment in human cancer by enhancing STING degradation

Role of TRIM29 in disease: What is and is not known

Tripartite motif-containing proteins (TRIMs), comprising the greatest subfamily of E3 ubiquitin ligases with approximately 80 members of this family, are widely distributed in mammalian cells. TRIMs actively participate in ubiquitination of target proteins, a type of post-translational modification associated with protein degradation and other functions. Tripartite motif-containing protein 29 (TRIM29), a member of the TRIM family, differs from other members of this family in that it lacks the RING finger structural domain containing cysteine and histidine residues that mediates DNA binding, protein-protein interactions, and ubiquitin ligase, at its N-terminus. The expression of TRIM29 was initially found to be associated with cancer and diabetic nephropathy progression, and antiviral immunity which is triggered by virus-derived nucleic acids binding to pattern recognition receptors (PRRs) on immune cells. Recently, TRIM29 has also been explored as a diagnostic biomarker and therapeutic target for some immune-related diseases. Here, we review the functions of TRIM29 in the progression of diseases and the inherent mechanisms, as well as the remaining gaps in the literature. A thorough understanding of the detailed regulatory mechanisms of TRIM29 will ultimately facilitate the development of different therapeutic strategies for various diseases.

MDSC: a new potential breakthrough in CAR-T therapy for solid tumors

Chimeric antigen receptor T (CAR-T) cell therapy has shown remarkable success in hematologic malignancies but has encountered challenges in effectively treating solid tumors. One major obstacle is the presence of the immunosuppressive tumor microenvironment (TME), which is mainly built by myeloid-derived suppressor cells (MDSCs). Recent studies have shown that MDSCs have a detrimental effect on CAR-T cells due to their potent immunosuppressive capabilities. Targeting MDSCs has shown promising results to enhance CAR-T immunotherapy in preclinical solid tumor models. In this review, we first highlight that MDSCs increase tumor proliferation, transition, angiogenesis and encourage circulating tumor cells (CTCs) extravasation leading to tumor progression and metastasis. Moreover, we describe the main characteristics of the immunosuppressive activities of MDSCs on T cells in TME. Most importantly, we summarize targeting therapeutic strategies of MDSCs in CAR-T therapies against solid tumors. These strategies include (1) therapeutic targeting of MDSCs through small molecule inhibitors and large molecule antibodies; (2) CAR-T targeting cancer cell antigen combination with MDSC modulatory agents; (3) cytokine receptor antigen-targeted CAR-T indirectly or directly targeting MDSCs reshapes TME; (4) modified natural killer (NK) cells expressing activating receptor directly targeting MDSCs; and (5) CAR-T directly targeting MDSC selective antigens. In the near future, we are expected to witness the improvement of CAR-T cell therapies for solid tumors by targeting MDSCs in clinical practice.

Galectin-9 regulates dendritic cell polarity and uropod contraction by modulating RhoA activity

Adaptive immunity relies on dendritic cell (DC) migration to transport antigens from tissues to lymph nodes. Galectins, a family of β-galactoside-binding proteins, control cell membrane organisation, exerting crucial roles in multiple physiological processes. Here, we report a novel mechanism underlying cell polarity and uropod retraction. We demonstrate that galectin-9 regulates chemokine-driven and basal DC migration both in humans and mice, indicating a conserved function for this lectin. We identified the underlying mechanism, namely a deficiency in cell rear contractility mediated by galectin-9 interaction with CD44 that in turn regulates RhoA activity. Analysis of DC motility in the 3D tumour-microenvironment revealed galectin-9 is also required for DC infiltration. Moreover, exogenous galectin-9 rescued the motility of tumour-immunocompromised human blood DCs, validating the physiological relevance of galectin-9 in DC migration and underscoring its implications for DC-based immunotherapies. Our results identify galectin-9 as a necessary mechanistic component for DC motility and highlight a novel role for the lectin in regulating cell polarity and contractility.

Leukocyte immunoglobulin-like receptor B4 (LILRB4) in acute myeloid leukemia: From prognostic biomarker to immunotherapeutic target

ABSTRACT

Leukocyte immunoglobulin-like receptor (LILR) B4 (also known as ILT3/CD85k) is an immune checkpoint protein that is highly expressed in solid tumors and hematological malignancies and plays a significant role in the pathophysiology of cancer. LILRB4 is highly expressed in acute myeloid leukemia (AML), and this phenotype is associated with adverse patient outcomes. Its differential expression in tumors compared to normal tissues, its presence in tumor stem cells, and its multifaceted roles in tumorigenesis position it as a promising therapeutic target in AML. Currently, several immunotherapies targeting LILRB4 are undergoing clinical trials. This review summarizes advancements made in the study of LILRB4 in AML, focusing on its structure, ligands, expression, and significance in normal tissues and AML; its protumorigenic effects and mechanisms in AML; and the application of LILRB4-targeted therapies in AML. These insights highlight the potential advantages of LILRB4 as an immunotherapeutic target in the context of AML.

Influencing immunity: role of extracellular vesicles in tumor immune checkpoint dynamics

Immune checkpoint proteins (ICPs) serve as critical regulators of the immune system, ensuring protection against damage due to overly activated immune responses. However, within the tumor environment, excessive ICP activation weakens antitumor immunity. Despite the development of numerous immune checkpoint blockade (ICB) drugs in recent years, their broad application has been inhibited by uncertainties about their clinical efficacy. A thorough understanding of ICP regulation in the tumor microenvironment is essential for advancing the development of more effective and safer ICB therapies. Extracellular vesicles (EVs), which are pivotal mediators of cell-cell communication, have been extensively studied and found to play key roles in the functionality of ICPs. Nonetheless, a comprehensive review summarizing the current knowledge about the crosstalk between EVs and ICPs in the tumor environment is lacking. In this review, we summarize the interactions between EVs and several widely studied ICPs as well as their potential clinical implications, providing a theoretical basis for further investigation of EV-related ICB therapeutic approaches.

Single Nuclei Sequencing Reveals Intratumoral Cellular Heterogeneity and Replication Stress in Adrenocortical Carcinoma

Adrenocortical carcinoma (ACC) is a rare endocrine malignancy with a poor prognosis and limited treatment options. Bulk genomic characterization of ACC has not yielded obvious therapeutic or immunotherapeutic targets, yet novel therapies are needed. We hypothesized that elucidating the intratumoral cellular heterogeneity by single nuclei RNA sequencing analyses would yield insights into potential therapeutic vulnerabilities of this disease. In addition to characterizing the immune cell and fibroblast landscape, our analyses of single nuclei gene expression profiles identified an adrenal cortex cell cluster exhibiting a program of replication stress and DNA damage response in primary and metastatic ACC. In vitro assessment of replication stress and DNA damage response using an ACC cell line and a series of newly-derived hormonally active patient-derived tumor organoids revealed ATR sensitivity. These findings provide novel mechanistic insight into ACC biology and suggest that an underlying dependency on ATR may be leveraged therapeutically in advanced ACC.

Recent advancements in cGAS-STING activation, tumor immune evasion, and therapeutic implications

The cGAS-STING signaling pathway is indeed a pivotal component of the immune system and serve as a crucial link between innate and adaptive immune responses. STING is involved in the cellular response to pathogen invasion and DNA damage, and which has important consequences for host defense mechanisms and cancer regulation. Ongoing research aiming to modulate the cGAS-STING pathway for improved clinical outcomes in cancer and autoimmune diseases is underway. Indeed, the interaction between the cGAS-STING pathway and immune evasion mechanisms is a complex and critical aspect of cancer biology. Pathogens and various host factors can exploit this pathway to reduce the effectiveness of cancer therapies, particularly immunotherapies. Thus, immunotherapies or combination therapies may assist in overcoming the immune suppression and improving clinical outcomes. This review explores recent advancements in understanding the cGAS-STING signaling pathway, with particular emphasis on its activation mechanisms and role in tumor immune evasion. The dual role of the pathway in boosting immune responses while simultaneously enabling tumors to evade the immune system makes it a crucial target for innovative cancer treatment approaches.Please confirm if the author names are presented accurately and in the correct sequence (given name, middle name/initial, family name). Author 2 Given name: [Md Mazedul] Last name [Islam], Author 3 Given name: [Mst Rubaiat Nazneen] Last name [Akhand] and Author 5 Given name: [Md Rashedunnabi] Last name [Akanda]. Also, kindly confirm the details in the metadata are correct.AQ1: Here Author 4 given name: [Byung-Yong] Last name [Park] is missing. Metadata are correct.

Effects of PACAP Deficiency on Immune Dysfunction and Peyer's Patch Integrity in Adult Mice

PACAP (pituitary adenylate cyclase activating polypeptide) is a widespread neuropeptide with cytoprotective and anti-inflammatory effects. It plays a role in innate and adaptive immunity, but data are limited about gut-associated lymphoid tissue. We aimed to reveal differences in Peyer's patches between wild-type (WT) and PACAP-deficient (KO) mice. Peyer's patch morphology from young (3-months-old) and aging (12-15-months-old) mice was examined, along with flow cytometry to assess immune cell populations, expression of checkpoint molecules (PD-1, PD-L1, TIM-3, Gal-9) and functional markers (CD69, granzyme B, perforin) in CD3+, CD4+, and CD8+ T cells. We found slight differences between aging, but not in young, WT, and KO mice. In WT mice, aging reduced CD8+ T cell numbers frequency and altered checkpoint molecule expression (higher TIM-3, granzyme B; lower Gal-9, CD69). CD4+ T cell frequency was higher with similar checkpoint alterations, indicating a regulatory shift. In PACAP KO mice, aging did not change cell population frequencies but led to higher TIM-3, granzyme B and lower PD-1, PD-L1, Gal-9, and CD69 expression in CD4+ and CD8+ T cells, with reduced overall T cell activity. Thus, PACAP deficiency impacts immune dysfunction by altering checkpoint molecules and T cell functionality, particularly in CD8+ T cells, suggesting complex immune responses by PACAP, highlighting its role in intestinal homeostasis and potential implications for inflammatory bowel diseases.

Galectin-1 Attenuates PDGF-Mediated AKT Signaling in Retinal Pigment Epithelial Cells

Galectins have the potential to interact with transmembrane glycoproteins to modulate their functions. Since galectin-1 interacts with PDGF-Rβ, we analyzed the effect of galectin-1 on PDGF-BB-mediated AKT signaling in primary human retinal pigment epithelial (RPE) cells and galectin-1-deficient immortalized human RPE cells (LGALS1-/-/ARPE-19) following incubation with PDGF-BB and galectin-1. Expression and localization of galectin-1, PDGF-Rβ and pAKT were investigated using western blot analysis and immunohistochemical staining. Cell proliferation of RPE cells was analyzed using BrdU ELISA. Following treatment of human RPE cells with human recombinant (hr)-galectin-1 and PDGF-BB, an intense clustering of PDGF-Rβ and colocalization with galectin-1 were detected. By Western blot analysis and immunocytochemistry of human RPE cells, an enhanced PDGF-BB-mediated expression of pAKT was observed, which was substantially reduced by additional incubation with hr-galectin-1. Vice versa, in LGALS1-/-/ARPE-19 cells, the PDGF-BB-induced pAKT signal was enhanced compared to wild-type cells. Furthermore, a decreased expression of PDGF-Rβ in human RPE cells was observed after treatment with PDGF-BB and hr-galectin-1, while in untreated LGALS1-/-/ARPE-19 cells, its constitutive expression was increased. In addition, after treatment of RPE cells with hr-galectin-1, the PDGF-BB-induced proliferation was markedly reduced. In summary, galectin-1 has the distinct potential to reduce PDGF-mediated pAKT signaling and proliferation in human RPE cells-an effect that is most likely facilitated via a decreased expression of PDGF-Rβ.

Exploring the role of the immune microenvironment in hepatocellular carcinoma: Implications for immunotherapy and drug resistance

Hepatocellular carcinoma (HCC), the most common type of liver tumor, is a leading cause of cancer-related deaths, and the incidence of liver cancer is still increasing worldwide. Curative hepatectomy or liver transplantation is only indicated for a small population of patients with early-stage HCC. However, most patients with HCC are not candidates for radical resection due to disease progression, leading to the choice of the conventional tyrosine kinase inhibitor drug sorafenib as first-line treatment. In the past few years, immunotherapy, mainly immune checkpoint inhibitors (ICIs), has revolutionized the clinical strategy for HCC. Combination therapy with ICIs has proven more effective than sorafenib, and clinical trials have been conducted to apply these therapies to patients. Despite significant progress in immunotherapy, the molecular mechanisms behind it remain unclear, and immune resistance is often challenging to overcome. Several studies have pointed out that the complex intercellular communication network in the immune microenvironment of HCC regulates tumor escape and drug resistance to immune response. This underscores the urgent need to analyze the immune microenvironment of HCC. This review describes the immunosuppressive cell populations in the immune microenvironment of HCC, as well as the related clinical trials, aiming to provide insights for the next generation of precision immunotherapy.

Emerging roles of tripartite motif family proteins (TRIMs) in breast cancer

Breast cancer (BC) is the most common malignant tumor worldwide. Despite enormous progress made in the past decades, the underlying mechanisms of BC remain further illustrated. Recently, TRIM family proteins proved to be engaged in BC progression through regulating various aspects. Here we reviewed the structures and basic functions of TRIM family members and first classified them into three groups according to canonical polyubiquitination forms that they could mediate: K48- only, K63- only, and both K48- and K63-linked ubiquitination. Afterwards, we focused on the specific biological functions and mechanisms of TRIMs in BCs, including tumorigenesis and invasiveness, drug sensitivity, tumor immune microenvironment (TIME), cell cycle, and metabolic reprogramming. We also explored the potential of TRIMs as novel biomarkers for predicting prognosis and future therapeutic targets in BC.

Immunosuppressive regulatory cells in cancer immunotherapy: restrain or modulate?

Immunosuppressive regulatory cells (IRCs) play important roles in negatively regulating immune response, and are mainly divided into myeloid-derived suppressor cells (MDSCs) and regulatory T cells (Tregs). Large numbers of preclinical and clinical studies have shown that inhibition or reduction of IRCs could effectively elevate antitumor immune responses. However, several studies also reported that excessive inhibition of IRCs function is one of the main reasons causing the side effects of cancer immunotherapy. Therefore, the reasonable regulation of IRCs is crucial for improving the safety and efficiency of cancer immunotherapy. In this review, we summarised the recent research advances in the cancer immunotherapy by regulating the proportion of IRCs, and discussed the roles of IRCs in regulating tumour immune evasion and drug resistance to immunotherapies. Furthermore, we also discussed how to balance the potential opportunities and challenges of using IRCs to improve the safety of cancer immunotherapies.

Harnessing innate immune pathways for therapeutic advancement in cancer

The innate immune pathway is receiving increasing attention in cancer therapy. This pathway is ubiquitous across various cell types, not only in innate immune cells but also in adaptive immune cells, tumor cells, and stromal cells. Agonists targeting the innate immune pathway have shown profound changes in the tumor microenvironment (TME) and improved tumor prognosis in preclinical studies. However, to date, the clinical success of drugs targeting the innate immune pathway remains limited. Interestingly, recent studies have shown that activation of the innate immune pathway can paradoxically promote tumor progression. The uncertainty surrounding the therapeutic effectiveness of targeted drugs for the innate immune pathway is a critical issue that needs immediate investigation. In this review, we observe that the role of the innate immune pathway demonstrates heterogeneity, linked to the tumor development stage, pathway status, and specific cell types. We propose that within the TME, the innate immune pathway exhibits multidimensional diversity. This diversity is fundamentally rooted in cellular heterogeneity and is manifested as a variety of signaling networks. The pro-tumor effect of innate immune pathway activation essentially reflects the suppression of classical pathways and the activation of potential pro-tumor alternative pathways. Refining our understanding of the tumor's innate immune pathway network and employing appropriate targeting strategies can enhance our ability to harness the anti-tumor potential of the innate immune pathway and ultimately bridge the gap from preclinical to clinical application.

Exosome-Mediated Antigen Delivery: Unveiling Novel Strategies in Viral Infection Control and Vaccine Design

Exosomes are small subtypes of extracellular vesicles (EVs) naturally released by different types of cells into their environment. Their physiological roles appear to be multiple, yet many aspects of their biological activities remain to be understood. These vesicles can transport and deliver a variety of cargoes and may serve as unconventional secretory vesicles. Thus, they play a crucial role as important vectors for intercellular communication and the maintenance of homeostasis. Exosome production and content can vary under several stresses or modifications in the cell microenvironment, influencing cellular responses and stimulating immunity. During infectious processes, exosomes are described as double-edged swords, displaying both beneficial and detrimental effects. Owing to their tractability, the analysis of EVs from multiple biofluids has become a booming tool for monitoring various pathologies, from infectious to cancerous origins. In this review, we present an overview of exosome features and discuss their particular and ambiguous functions in infectious contexts. We then focus on their properties as diagnostic or therapeutic tools. In this regard, we explore the capacity of exosomes to vectorize immunogenic viral antigens and their function in mounting adaptive immune responses. As exosomes provide interesting platforms for antigen presentation, we further review the available data on exosome engineering, which enables peptides of interest to be exposed at their surface. In the light of all these data, exosomes are emerging as promising avenues for vaccine strategies.

Discovery of galectin-8 as an LILRB4 ligand driving M-MDSCs defines a class of antibodies to fight solid tumors

LILRB4 is an immunosuppressive receptor, and its targeting drugs are undergoing multiple preclinical and clinical trials. Currently, the absence of a functional LILRB4 ligand in solid tumors not only limits the strategy of early antibody screening but also leads to the lack of companion diagnostic (CDx) criteria, which is critical to the objective response rate in early-stage clinical trials. Here, we show that galectin-8 (Gal-8) is a high-affinity functional ligand of LILRB4, and its ligation induces M-MDSC by activating STAT3 and inhibiting NF-κB. Significantly, Gal-8, but not APOE, can induce MDSC, and both ligands bind LILRB4 noncompetitively. Gal-8 expression promotes in vivo tumor growth in mice, and the knockout of LILRB4 attenuates tumor growth in this context. Antibodies capable of functionally blocking Gal-8 are able to suppress tumor growth in vivo. These results identify Gal-8 as an MDSC-driving ligand of LILRB4, and they redefine a class of antibodies for solid tumors.

Encapsulation and assessment of therapeutic cargo in engineered exosomes: a systematic review

Exosomes are nanoscale extracellular vesicles secreted by cells and enclosed by a lipid bilayer membrane containing various biologically active cargoes such as proteins, lipids, and nucleic acids. Engineered exosomes generated through genetic modification of parent cells show promise as drug delivery vehicles, and they have been demonstrated to have great therapeutic potential for treating cancer, cardiovascular, neurological, and immune diseases, but systematic knowledge is lacking regarding optimization of drug loading and assessment of delivery efficacy. This review summarizes current approaches for engineering exosomes and evaluating their drug delivery effects, and current techniques for assessing exosome drug loading and release kinetics, cell targeting, biodistribution, pharmacokinetics, and therapeutic outcomes are critically examined. Additionally, this review synthesizes the latest applications of exosome engineering and drug delivery in clinical translation. The knowledge compiled in this review provides a framework for the rational design and rigorous assessment of exosomes as therapeutics. Continued advancement of robust characterization methods and reporting standards will accelerate the development of exosome engineering technologies and pave the way for clinical studies.

Harnessing the innate immune system by revolutionizing macrophage-mediated cancer immunotherapy

Immunotherapy is a promising and safer alternative to conventional cancer therapies. It involves adaptive T-cell therapy, cancer vaccines, monoclonal antibodies, immune checkpoint blockade (ICB), and chimeric antigen receptor (CAR) based therapies. However, most of these modalities encounter restrictions in solid tumours owing to a dense, highly hypoxic and immune-suppressive microenvironment as well as the heterogeneity of tumour antigens. The elevated intra-tumoural pressure and mutational rates within fastgrowing solid tumours present challenges in efficient drug targeting and delivery. The tumour microenvironment is a dynamic niche infiltrated by a variety of immune cells, most of which are macrophages. Since they form a part of the innate immune system, targeting macrophages has become a plausible immunotherapeutic approach. In this review, we discuss several versatile approaches (both at pre-clinical and clinical stages) such as the direct killing of tumour-associated macrophages, reprogramming pro-tumour macrophages to anti-tumour phenotypes, inhibition of macrophage recruitment into the tumour microenvironment, novel CAR macrophages, and genetically engineered macrophages that have been devised thus far. These strategies comprise a strong and adaptable macrophage-toolkit in the ongoing fight against cancer and by understanding their significance, we may unlock the full potential of these immune cells in cancer therapy.

Innate immunity: Looking beyond T-cells in radiation and immunotherapy combinations

Radiation therapy is an established and effective anti-cancer treatment modality. Extensive pre-clinical experimentation has demonstrated that the pro-inflammatory properties of irradiation may be synergistic with checkpoint immunotherapy. Radiation induces double-stranded DNA breaks (dsDNA). Sensing of the dsDNA activates the cGAS/STING pathway, producing Type 1 interferons essential to recruiting antigen-presenting cells (APCs). Radiation promotes cytotoxic CD8 T-cell recruitment by releasing tumour-associated antigens captured and cross-presented by surveying antigen-presenting cells. Radiation-induced vascular normalisation may further promote T-cell trafficking and drug delivery. Radiation is also immunosuppressive. Recruitment of regulatory T cells (Tregs) and innate cells such as myeloid-derived suppressive cells (m-MDSCs) all counteract the immunostimulatory properties of radiation. Many innate immune cell types operate at the interface of the adaptive immune response. Innate immune cells, such as m-MDSCs, can exert their immunosuppressive effects by expressing immune checkpoints such as PD-L1, further highlighting the potential of combined radiation and checkpoint immunotherapy. Several early-phase clinical studies investigating the combination of radiation and immunotherapy have been disappointing. A greater appreciation of radiotherapy's impact on the innate immune system is essential to optimise radioimmunotherapy combinations. This review will summarise the impact of radiotherapy on crucial cells of the innate immune system and vital immunosuppressive cytokines.

Chemical Biology Perspectives on STING Agonists as Tumor Immunotherapy

Stimulator of interferon genes (STING) is a crucial adaptor protein in the innate immune response. STING activation triggers cytokine secretion, including type I interferon and initiates T cell-mediated adaptive immunity. The activated immune system converts "cold tumors" into "hot tumors" that are highly responsive to T cells by recruiting them to the tumor microenvironment, ultimately leading to potent and long-lasting antitumor effects. Unlike most immune checkpoint inhibitors, STING agonists represent a groundbreaking class of innate immune agonists that hold great potential for effectively targeting various cancer populations and are poised to become a blockbuster in tumor immunotherapy. This review will focus on the correlation between the STING signaling pathway and tumor immunity, as well as explore the impact of STING activation on other biological processes. Ultimately, we will summarize the development and optimization of STING agonists from a medicinal chemistry perspective, evaluate their potential in cancer therapy, and identify possible challenges for future advancement.

An integrated study to decipher immunosuppressive cellular communication in the PDAC environment

Pancreatic ductal adenocarcinoma (PDAC) is one the most aggressive cancers and characterized by a highly rigid and immunosuppressive tumor microenvironment (TME). The extensive cellular interactions are known to play key roles in the immune evasion, chemoresistance, and poor prognosis. Here, we used the spatial transcriptomics, scRNA-seq, and bulk RNA-seq datasets to enhance the insights obtained from each to decipher the cellular communication in the TME. The complex crosstalk in PDAC samples was revealed by the single-cell and spatial transcriptomics profiles of the samples. We show that tumor-associated macrophages (TAMs) are the central cell types in the regulation of microenvironment in PDAC. They colocalize with the cancer cells and tumor-suppressor immune cells and take roles to provide an immunosuppressive environment. LGALS9 gene which is upregulated in PDAC tumor samples in comparison to healthy samples was also found to be upregulated in TAMs compared to tumor-suppressor immune cells in cancer samples. Additionally, LGALS9 was found to be the primary component in the crosstalk between TAMs and the other cells. The widespread expression of P4HB gene and its interaction with LGALS9 was also notable. Our findings point to a profound role of TAMs via LGALS9 and its interaction with P4HB that should be considered for further elucidation as target in the combinatory immunotherapies for PDAC.

Precision medicine in nasopharyngeal carcinoma: comprehensive review of past, present, and future prospect

Nasopharyngeal carcinoma (NPC) is an aggressive malignancy with high propensity for lymphatic spread and distant metastasis. It is prominent as an endemic malignancy in Southern China and Southeast Asia regions. Studies on NPC pathogenesis mechanism in the past decades such as through Epstein Barr Virus (EBV) infection and oncogenic molecular aberrations have explored several potential targets for therapy and diagnosis. The EBV infection introduces oncoviral proteins that consequently hyperactivate many promitotic pathways and block cell-death inducers. EBV infection is so prevalent in NPC patients such that EBV serological tests were used to diagnose and screen NPC patients. On the other hand, as the downstream effectors of oncogenic mechanisms, the promitotic pathways can potentially be exploited therapeutically. With the apparent heterogeneity and distinct molecular aberrations of NPC tumor, the focus has turned into a more personalized treatment in NPC. Herein in this comprehensive review, we depict the current status of screening, diagnosis, treatment, and prevention in NPC. Subsequently, based on the limitations on those aspects, we look at their potential improvements in moving towards the path of precision medicine. The importance of recent advances on the key molecular aberration involved in pathogenesis of NPC for precision medicine progression has also been reported in the present review. Besides, the challenge and future outlook of NPC management will also be highlighted.

Galectin-1 Mediates Chronic STING Activation in Tumors to Promote Metastasis through MDSC Recruitment

The immune system plays a crucial role in the regulation of metastasis. Tumor cells systemically change immune functions to facilitate metastatic progression. Through this study, we deciphered how tumoral galectin-1 (Gal1) expression shapes the systemic immune environment to promote metastasis in head and neck cancer (HNC). In multiple preclinical models of HNC and lung cancer in immunogenic mice, Gal1 fostered the establishment of a premetastatic niche through polymorphonuclear myeloid-derived suppressor cells (PMN-MDSC), which altered the local microenvironment to support metastatic spread. RNA sequencing of MDSCs from premetastatic lungs in these models demonstrated the role of PMN-MDSCs in collagen and extracellular matrix remodeling in the premetastatic compartment. Gal1 promoted MDSC accumulation in the premetastatic niche through the NF-κB signaling axis, triggering enhanced CXCL2-mediated MDSC migration. Mechanistically, Gal1 sustained NF-κB activation in tumor cells by enhancing stimulator of interferon gene (STING) protein stability, leading to prolonged inflammation-driven MDSC expansion. These findings suggest an unexpected protumoral role of STING activation in metastatic progression and establish Gal1 as an endogenous-positive regulator of STING in advanced-stage cancers.

SIGNIFICANCE

Galectin-1 increases STING stability in cancer cells that activates NF-κB signaling and CXCL2 expression to promote MDSC trafficking, which stimulates the generation of a premetastatic niche and facilitates metastatic progression.

Inhibition of Galectin-9 sensitizes tumors to anthracycline treatment via inducing antitumor immunity

Anthracyclines are a class of conventionally and routinely used first-line chemotherapy drugs for cancer treatment. In addition to the direct cytotoxic effects, increasing evidence indicates that the efficacy of the drugs also depends on immunomodulatory effects with unknown mechanisms. Galectin-9 (Gal-9), a member of the β-galactoside-binding protein family, has been demonstrated to induce T-cell death and promote immunosuppression in the tumor microenvironment. Here, we asked whether anthracycline-mediated immunomodulatory activity might be related to Gal-9. We found that combining doxorubicin with anti-Gal-9 therapy significantly inhibited tumor growth and prolonged overall survival in immune-competent syngeneic mouse models. Moreover, Gal-9 expression was increased in response to doxorubicin in various human and murine cancer cell lines. Mechanistically, doxorubicin induced tumoral Gal-9 by activating the STING/interferon β pathway. Clinically, Gal-9 and p-STING levels were elevated in the tumor tissues of breast cancer patients treated with anthracyclines. Our study demonstrates Gal-9 upregulation in response to anthracyclines as a novel mechanism mediating immune escape and suggests targeting Gal-9 in combination with anthracyclines as a promising therapeutic strategy for cancer treatment.

Immunotherapy for nasopharyngeal carcinoma: Current status and prospects (Review)

Nasopharyngeal carcinoma (NPC) is an epithelial tumor located in the nasopharynx and is highly associated with Epstein‑Barr virus (EBV) infection. Although radiotherapy alone can cure ~90% of patients with early‑stage disease, >70% of patients with NPC have locoregionally advanced or metastatic disease at the first diagnosis due to the insidious and aggressive nature of NPC. After comprehensive radiochemotherapy, 20‑30% of patients with advanced NPC still fail treatment, mainly due to recurrence and/or metastasis (R/M). Conventional salvage treatments, such as radiotherapy, chemotherapy and surgery, are suboptimal and frequently accompanied by severe adverse effects and limited efficacy. In recent years, immunotherapy has emerged as a promising treatment modality for R/M NPC. An increasing number of clinical studies have investigated the safety and efficacy of immunotherapy for advanced NPC and have shown considerable progress. In the present review, the rationale for the use of immunotherapy to treat NPC was summarized and the current status, progress and challenges of NPC clinical research on different immunotherapeutic approaches were highlighted, including immune checkpoint inhibitors, vaccines, immunomodulators, adoptive cell transfer and EBV‑specific monoclonal antibodies. The comprehensive overview of immunotherapy in NPC may provide insight for clinical practice and future investigation.

Immune Checkpoint Profiling in Humanized Breast Cancer Mice Revealed Cell-Specific LAG-3/PD-1/TIM-3 Co-Expression and Elevated PD-1/TIM-3 Secretion

Checkpoint blockade is particularly based on PD-1/PD-L1-inhibiting antibodies. However, an efficient immunological tumor defense can be blocked not only by PD-(L)1 but also by the presence of additional immune checkpoint molecules. Here, we investigated the co-expression of several immune checkpoint proteins and the soluble forms thereof (e.g., PD-1, TIM-3, LAG-3, PD-L1, PD-L2 and others) in humanized tumor mice (HTM) simultaneously harboring cell line-derived (JIMT-1, MDA-MB-231, MCF-7) or patient-derived breast cancer and a functional human immune system. We identified tumor-infiltrating T cells with a triple-positive PD-1, LAG-3 and TIM-3 phenotype. While PD-1 expression was increased in both the CD4 and CD8 T cells, TIM-3 was found to be upregulated particularly in the cytotoxic T cells in the MDA-MB-231-based HTM model. High levels of soluble TIM-3 and galectin-9 (a TIM-3 ligand) were detected in the serum. Surprisingly, soluble PD-L2, but only low levels of sPD-L1, were found in mice harboring PD-L1-positive tumors. Analysis of a dataset containing 3039 primary breast cancer samples on the R2 Genomics Analysis Platform revealed increased TIM-3, galectin-9 and LAG-3 expression, not only in triple-negative breast cancer but also in the HER2⁺ and hormone receptor-positive breast cancer subtypes. These data indicate that LAG-3 and TIM-3 represent additional key molecules within the breast cancer anti-immunity landscape.

Galectin-9 and myeloid-derived suppressor cell as prognostic indicators for chronic lymphocytic leukemia

BACKGROUND

Galectin-9 and myeloid-derived suppressor cells (MDSCs) have an important role in tumors, but their clinical values in chronic lymphocytic leukemia (CLL) have not been fully elucidated. This study aimed to analyze the prognosis values of Galectin-9 and MDSCs in CLL.

METHODS

The concentrations of Galectin-9, argininase-1, and inducible nitric oxide synthase in serum were detected by enzyme-linked immune sorbent assay. The expression of Tim-3 protein in peripheral blood mononuclear cell was detected by Western blot. Flow cytometry was used to analyze the percentages of Tim-3 on T-cells (CD3+ T, CD4+ T, and CD8+ T cells) and MDSCs.

RESULTS

Our results showed that Galectin-9 and MDSCs significantly increased in CLL patients and were closely related to the disease progression. Patient's receiver operating characteristic, progression-free survival, and Cox regression analysis showed that Galectin9 and MDSCs were poor prognostic factors of CLL.

CONCLUSION

Galectin-9 and MDSCs were associated with clinical progression and could be important prognostic indicators for CLL.

Expression of Gal-9 on Dendritic Cells and Soluble Forms of TIM-3/Gal-9 in Patients Suffering from Endometriosis

Immune system dysregulation is clinically evident in the pathogenesis of endometriosis (EMS). Changes in the dendritic cells (DCs) activity or phenotype may be involved in the implantation and growth of endometrial tissue outside the uterus in the disease. The TIM-3/Gal-9 axis is implicated in the development of immune tolerance. However, the knowledge about the exact role of this pathway in the EMS is extremely poor. In the present study, we evaluated the expression of Gal-9 on myeloid DCs (mDCs) and plasmacytoid DCs (pDCs) in the peripheral blood (PB) and peritoneal fluid (PF) of both EMS patients (n = 82) and healthy subjects (n = 10) via flow cytometry. We also investigated the concentrations of soluble Gal-9 and TIM-3 in the plasma and PF of EMS patients and the control group using ELISA. We showed significantly elevated percentages of mDCs-Gal-9⁺ and pDCs-Gal-9⁺, and significantly higher concentrations of the soluble form of Gal-9 and TIM-3 in the PF of EMS patients than in circulation. Our results led us to conclude that the accumulation of Gal-9 expressing mDCs and pDCs in the PF and high sTIM-3/Gal-9 production in the peritoneal cavity could represent the hallmark of immune regulation in EMS patients, which may augment the inflammatory process and development/maintenance of local immunosuppression.

Galectin-9 Facilitates Epstein-Barr Virus Latent Infection and Lymphomagenesis in Human B Cells

The immune regulator galectin-9 (Gal-9) is commonly involved in the regulation of cell proliferation, but with various impacts depending on the cell type. Here, we revealed that Gal-9 expression was persistently increased in Epstein-Barr virus (EBV)-infected primary B cells from the stage of early infection to the stage of mature lymphoblastoid cell lines (LCLs). This sustained upregulation paralleled that of gene sets related to cell proliferation, such as oxidative phosphorylation, cell cycle activation, and DNA replication. Knocking down or blocking Gal-9 expression obstructed the establishment of latent infection and outgrowth of EBV-infected B cells, while exogenous Gal-9 protein promoted EBV acute and latent infection and outgrowth of EBV-infected B cells at the early infection stage. Mechanically, stimulator of interferon gene (STING) activation or signal transducer and activator of transcription 3 (STAT3) inhibition impeded the outgrowth of EBV-infected B cells and promotion of Gal-9-induced lymphoblastoid cell line (LCL) transformation. Accordingly, Gal-9 expression was upregulated by forced EBV nuclear antigen 1 (EBNA1) expression in 293T cells in vitro. Clinical data showed that Gal-9 expression in B-cell lymphomas (BCLs) correlated positively with EBNA1 and disease stage. Targeting Gal-9 slowed LCL tumor growth and metastasis in xenografted immunodeficient mice. These findings highlight an oncogenic role of Gal-9 in EBV-associated BCLs, indicating that Gal-9 boosts the transformation of EBV-infected B cells. IMPORTANCE The cross talk between Epstein-Barr virus (EBV) and the host cell transcriptome assumes important roles in the oncogenesis of EBV-associated malignancies. Here, we first observed that endogenous Gal-9 expression was persistently increased along with an overturned V-type change in antivirus signaling during the immortalization of EBV-transformed B cells. Upregulation of Gal-9 promoted the outgrowth and latent infection of EBV-infected B cells, which was linked to B-cell-origin tumors by suppressing STING signaling and subsequently promoting STAT3 phosphorylation. EBV nuclear antigen EBNA1 induced Gal-9 expression and formed a positive feedback loop with Gal-9 in EBV-infected B cells. Tumor Gal-9 levels were positively correlated with disease stage and EBNA1 expression in patients with B-cell lymphomas (BCLs). Targeting Gal-9 slowed the growth and metastases of LCL tumors in immunodeficient mice. Altogether, our findings indicate that Gal-9 is involved in the lymphomagenesis of EBV-positive BCLs through cross talk with EBNA1 and STING signals.

Galectins as pivotal components in oncogenesis and immune exclusion in human malignancies

Galectins are galactoside-binding proteins, exerting numerous functions inside and outside the cell, particularly conferring adaptation to stress factors. For most of them, aberrant expression profiles have been reported in the context of cancer. Albeit not being oncogenic drivers, galectins can be harnessed to exacerbate the malignant phenotype. Their impact on disease establishment and progression is not limited to making cancer cells resistant to apoptosis, but is prominent in the context of the tumor microenvironment, where it fosters angiogenesis, immune escape and exclusion. This review focuses mainly on Gal-1, Gal-3 and Gal-9 for which the involvement in cancer biology is best known. It presents the types of galectin dysregulations, attempts to explain the mechanisms behind them and analyzes the different ways in which they favor tumour growth. In an era where tumour resistance to immunotherapy appears as a major challenge, we highlight the crucial immunosuppressive roles of galectins and the potential therapeutic benefits of combinatorial approaches including galectin inhibition.

The E3 ubiquitin ligases regulate PD-1/PD-L1 protein levels in tumor microenvironment to improve immunotherapy

The tumor microenvironment (TME) is the tumor surrounding environment, which is critical for tumor development and progression. TME is also involved in clinical intervention and treatment outcomes. Modulation of TME is useful for improving therapy strategies. PD-L1 protein on tumor cells interacts with PD-1 protein on T cells, contributing to T cell dysfunction and exhaustion, blockage of the immune response. Evidence has demonstrated that the expression of PD-1/PD-L1 is associated with clinical response to anti-PD-1/PD-L1 therapy in cancer patients. It is important to discuss the regulatory machinery how PD-1/PD-L1 protein is finely regulated in tumor cells. In recent years, studies have demonstrated that PD-1/PD-L1 expression was governed by various E3 ubiquitin ligases in TME, contributing to resistance of anti-PD-1/PD-L1 therapy in human cancers. In this review, we will discuss the role and molecular mechanisms of E3 ligases-mediated regulation of PD-1 and PD-L1 in TME. Moreover, we will describe how E3 ligases-involved PD-1/PD-L1 regulation alters anti-PD-1/PD-L1 efficacy. Altogether, targeting E3 ubiquitin ligases to control the PD-1/PD-L1 protein levels could be a potential strategy to potentiate immunotherapeutic effects in cancer patients.

"Open Sesame" to the complexity of pattern recognition receptors of myeloid-derived suppressor cells in cancer

Pattern recognition receptors are primitive sensors that arouse a preconfigured immune response to broad stimuli, including nonself pathogen-associated and autologous damage-associated molecular pattern molecules. These receptors are mainly expressed by innate myeloid cells, including granulocytes, monocytes, macrophages, and dendritic cells. Recent investigations have revealed new insights into these receptors as key players not only in triggering inflammation processes against pathogen invasion but also in mediating immune suppression in specific pathological states, including cancer. Myeloid-derived suppressor cells are preferentially expanded in many pathological conditions. This heterogeneous cell population includes immunosuppressive myeloid cells that are thought to be associated with poor prognosis and impaired response to immune therapies in various cancers. Identification of pattern recognition receptors and their ligands increases the understanding of immune-activating and immune-suppressive myeloid cell functions and sheds light on myeloid-derived suppressor cell differences from cognate granulocytes and monocytes in healthy conditions. This review summarizes the different expression, ligand recognition, signaling pathways, and cancer relations and identifies Toll-like receptors as potential new targets on myeloid-derived suppressor cells in cancer, which might help us to decipher the instruction codes for reverting suppressive myeloid cells toward an antitumor phenotype.

The cyclic guanosine monophosphate synthase-stimulator of interferon genes pathway as a potential target for tumor immunotherapy

Cyclic guanosine monophosphate-adenosine monophosphate (cGAMP) synthase (cGAS) detects infections or tissue damage by binding to microbial or self-DNA in the cytoplasm. Upon binding DNA, cGAS produces cGAMP that binds to and activates the adaptor protein stimulator of interferon genes (STING), which then activates the kinases IKK and TBK1 to induce the secretion of interferons and other cytokines. Recently, a series of studies demonstrated that the cGAS-STING pathway, a vital component of host innate immunity, might play an important role in anticancer immunity, though its mechanism remains to be elucidated. In this review, we highlight the latest understanding of the cGAS-STING pathway in tumor development and the advances in combination therapy of STING agonists and immunotherapy.

Epigenetically suppressed tumor cell intrinsic STING promotes tumor immune escape

DNA sensing through the cGAS-STING pathway plays an important role in cancer immunosurveillance. Pharmaceutical activation of STING in the tumor environment is considered an attractive approach to induce anti-tumor immunity, but had limited efficacy in the clinic. Several studies have found that STING is epigenetically silenced in many tumors, including colon cancer. This suggests that STING silencing in tumor cells contributes to immune escape and may limit the application of STING agonists. We previously found that inhibition of the KDM5 family histone demethylases restored STING expression in human breast cancer cells and activated the cGAS-STING pathway. In this study, we used MC38 and CT26 syngeneic mouse colorectal cancer models to show that loss of STING in tumor cells accelerates tumor growth. KDM5 inhibitors activate STING expression in mouse colorectal cancer cells and suppress colon cancer growth in immune competent mice in a STING-dependent manner. This study highlights KDM5 inhibitors as novel immune modulators in cancer therapies.

Cancer fitness genes: emerging therapeutic targets for metastasis

Development of cancer therapeutics has traditionally focused on targeting driver oncogenes. Such an approach is limited by toxicity to normal tissues and treatment resistance. A class of 'cancer fitness genes' with crucial roles in metastasis have been identified. Elevated or altered activities of these genes do not directly cause cancer; instead, they relieve the stresses that tumor cells encounter and help them adapt to a changing microenvironment, thus facilitating tumor progression and metastasis. Importantly, as normal cells do not experience high levels of stress under physiological conditions, targeting cancer fitness genes is less likely to cause toxicity to noncancerous tissues. Here, we summarize the key features and function of cancer fitness genes and discuss their therapeutic potential.

Myeloid-derived suppressor cells in head and neck squamous cell carcinoma

Myeloid-derived suppressor cells (MDSCs), which originated from hematopoietic stem cells, are heterogeneous population of cells that have different differentiation patterns and widely presented in tumor microenvironment. For tumor research, myeloid suppressor cells have received extensive attention since their discovery due to their specific immunosuppressive properties, and the mechanisms of immunosuppression and therapeutic approaches for MDSCs have been investigated in a variety of different types of malignancies. To improve the efficacy of treatment for head and neck squamous cell carcinoma (HNSCC), a disease with a high occurrence, immunotherapy has gradually emerged in after traditional surgery and subsequent radiotherapy and chemotherapy, and has made some progress. In this review, we introduced the mechanisms on the development, differentiation, and elimination of MDSCs and provided a detailed overview of the mechanisms behind the immunosuppressive properties of MDSCs. We summarized the recent researches on MDSCs in HNSCC, especially for targeting-MDSCs therapy and combination with other types of therapy such as immune checkpoint blockade (ICB). Furthermore, we looked at drug delivery patterns and collected the current diverse drug delivery systems for the improvement that contributed to therapy against MDSCs in HNSCC. Most importantly, we made possible outlooks for the future research priorities, which provide a basis for further study on the clinical significance and therapeutic value of MDSCs in HNSCC.

Multifaceted functions of STING in human health and disease: from molecular mechanism to targeted strategy

Since the discovery of Stimulator of Interferon Genes (STING) as an important pivot for cytosolic DNA sensation and interferon (IFN) induction, intensive efforts have been endeavored to clarify the molecular mechanism of its activation, its physiological function as a ubiquitously expressed protein, and to explore its potential as a therapeutic target in a wide range of immune-related diseases. With its orthodox ligand 2'3'-cyclic GMP-AMP (2'3'-cGAMP) and the upstream sensor 2'3'-cGAMP synthase (cGAS) to be found, STING acquires its central functionality in the best-studied signaling cascade, namely the cGAS-STING-IFN pathway. However, recently updated research through structural research, genetic screening, and biochemical assay greatly extends the current knowledge of STING biology. A second ligand pocket was recently discovered in the transmembrane domain for a synthetic agonist. On its downstream outputs, accumulating studies sketch primordial and multifaceted roles of STING beyond its cytokine-inducing function, such as autophagy, cell death, metabolic modulation, endoplasmic reticulum (ER) stress, and RNA virus restriction. Furthermore, with the expansion of the STING interactome, the details of STING trafficking also get clearer. After retrospecting the brief history of viral interference and the milestone events since the discovery of STING, we present a vivid panorama of STING biology taking into account the details of the biochemical assay and structural information, especially its versatile outputs and functions beyond IFN induction. We also summarize the roles of STING in the pathogenesis of various diseases and highlight the development of small-molecular compounds targeting STING for disease treatment in combination with the latest research. Finally, we discuss the open questions imperative to answer.

Plasma galectins and metabolites in advanced head and neck carcinomas: evidence of distinct immune characteristics linked to hypopharyngeal tumors

Extra-cellular galectins 1, 3 and 9 (gal-1, -3 and -9) are known to act as soluble immunosuppressive agents in various malignancies. Previous publications have suggested that their expression is dependent on the metabolic status of producing cells and reciprocally that they can influence metabolic pathways in their target cells. Very little is known about the status of gal-1, -3 and -9 in patients bearing head and neck squamous cell carcinomas (HNSCC) and about their relationships with the systemic metabolic condition. This study was conducted in plasma samples from a prospective cohort of 83 HNSCC patients with advanced disease. These samples were used to explore the distribution of gal-1, -3 and -9 and simultaneously to profile a series of 87 metabolites assessed by mass spectrometry. We identified galectin and metabolic patterns within five disease categories defined according to the primary site and human papillomavirus (HPV) status (HPV-positive and -negative oropharyngeal carcinomas, carcinomas of the oral cavity, hypopharynx and larynx carcinomas). Remarkably, samples related to hypopharyngeal carcinomas displayed the highest average concentration of gal-9 (p = .017) and a trend toward higher concentrations of kynurenine, a potential factor of tumor growth and immune suppression. In contrast, there was a tendency toward higher concentrations of fatty acids in samples related to oral cavity. These observations emphasize the diversity of HPV-negative HNSCCs. Depending on their primary site, they evolve into distinct types of immune and metabolic landscapes that seem to be congruent with specific oncogenic mechanisms.

The cGAS-STING pathway: Post-translational modifications and functional implications in diseases

Recent studies have illustrated the functional significance of DNA recognition in the activation of innate immune responses among a variety of diseases. The cyclic GMP-AMP synthase-stimulator of interferon genes (cGAS-STING) pathway has been found to be modulated by post-translational modifications and can regulate the immune response via type I IFNs. Accumulating evidence indicates a pivotal role of cGAS-STING signaling, being protective or pathogenic, in the development of diseases. Thus, a comprehensive understanding of the post-translational modifications of cGAS-STING pathway and their role in disease development will provide insights in predicting individual disease outcomes and developing appropriate therapies. In this review, we will discuss the regulation of the cGAS-STING pathway and its implications in disease pathologies, as well as pharmacologic strategies to target the cGAS-STING pathway for therapeutic intervention.

Galectin-9: A novel promoter of atherosclerosis progression

BACKGROUND AND AIMS

Atherosclerosis is widely accepted to be an inflammatory disease driven by lipid accumulation and leukocyte recruitment. More recently, galectins, a family of β-galactoside binding proteins, have been shown to play a role in leukocyte recruitment among other immunomodulatory functions. Galectin (Gal) -9, a tandem repeat type galectin expressed by the endothelium in inflammatory environments, has been proposed to promote leukocyte recruitment. However, the role of Gal-9 in the context of monocyte recruitment remains elusive.

METHODS AND RESULTS

Here, we characterise the immunomodulatory role of Gal-9 in context of atherosclerosis. We show that ApoE-/-Gal-9-/- mice have a significantly reduced aortic plaque burden compared to their ApoE-/- littermate controls after 12 weeks of high fat diet. RNA sequencing data from two independent studies reveal Lgals9 expression in leukocyte clusters isolated from murine atherosclerotic plaques. Additionally, soluble Gal-9 protein induces monocyte activation and a pro-inflammatory phenotype in macrophages. Furthermore, we show that immobilised recombinant Gal-9 acts as capture and adhesion molecule for CD14+ monocytes in a β2-integrin and glycan dependent manner, while adhesion of monocytes to stimulated endothelium is reduced when Gal-9 is knocked down. Gal-9 also facilitates enhanced recruitment of leukocytes from peripheral arterial disease (PAD) patients compared to healthy young and aged controls. We further characterise the endothelium as source of circulating Gal-9, which is increased in plasma of PAD patients compared to healthy controls.

CONCLUSIONS

These results highlight a pathological role for Gal-9 as promoter of monocyte recruitment and atherosclerotic plaque progression, making it a novel target in the prevention of plaque formation and progression.

Galectin-9/Tim-3 pathway mediates dopaminergic neurodegeneration in MPTP-induced mouse model of Parkinson's disease

Galectin-9 (Gal-9) is a crucial immunoregulatory mediator in the central nervous system. Microglial activation and neuroinflammation play a key role in the degeneration of dopaminergic neurons in the substantia nigra (SN) in Parkinson's disease (PD). However, it remains unknown whether Gal-9 is involved in the pathogenesis of PD. We found that MPP+ treatment promoted the expression of Gal-9 and pro-inflammatory cytokines (IL-6, IL-1β, TNF-α, and MIP-1α) in a concentration-dependent manner in BV2 cells. Gal-9 enhanced neurodegeneration and oxidative stress induced by MPP+ in SH-SY5Y cells and primary neurons. Importantly, deletion of Gal-9 or blockade of Tim-3 ameliorated microglial activation, reduced dopaminergic neuronal loss, and improved motor performance in an MPTP-induced mouse model of PD. These observations demonstrate a pathogenic role of the Gal-9/Tim-3 pathway in exacerbating microglial activation, neuroinflammation, oxidative stress, and dopaminergic neurodegeneration in the pathogenesis of PD.

A Targeted Proteomics Approach for Screening Serum Biomarkers Observed in the Early Stage of Type I Endometrial Cancer

Endometrial cancer (EC) is the most common gynecologic malignancy, and it arises in the inner part of the uterus. Identification of serum biomarkers is essential for diagnosing the disease at an early stage. In this study, we selected 44 healthy controls and 44 type I EC at tumor stage 1, and we used the Immuno-oncology panel and the Target 96 Oncology III panel to simultaneously detect the levels of 92 cancer-related proteins in serum, using a proximity extension assay. By applying this methodology, we identified 20 proteins, associated with the outcome at binary logistic regression, with a p-value below 0.01 for the first panel and 24 proteins with a p-value below 0.02 for the second one. The final multivariate logistic regression model, combining proteins from the two panels, generated a model with a sensitivity of 97.67% and a specificity of 83.72%. These results support the use of the proposed algorithm after a validation phase.

Roles of ubiquitination in the crosstalk between tumors and the tumor microenvironment (Review)

The interaction between a tumor and the tumor microenvironment (TME) plays a key role in tumorigenesis and tumor progression. Ubiquitination, a crucial post-translational modification for regulating protein degradation and turnover, plays a role in regulating the crosstalk between a tumor and the TME. Thus, identifying the roles of ubiquitination in the process may assist researchers to investigate the mechanisms underlying tumorigenesis and tumor progression. In the present review article, new insights into the substrates for ubiquitination that are involved in the regulation of hypoxic environments, angiogenesis, chronic inflammation-mediated tumor formation, and the function of cancer-associated fibroblasts and infiltrating immune cells (tumor-associated macrophages, T-cells, myeloid-derived suppressor cells, dendritic cells, and natural killer cells) are summarized. In addition, the potential targets of the ubiquitination proteasome system within the TME for cancer therapy and their therapeutic effects are reviewed and discussed.

Reduced Tripartite Motif-Containing Protein 29 Deteriorates the Severity of Severe Acute Pancreatitis

OBJECTIVES

Severe acute pancreatitis (SAP) is the most serious subtype of acute pancreatitis, manifested as multiple-organ failure resulting in high morbidity and mortality. Based on the role of tripartite motif-containing protein 29 (TRIM29) in immune responses, we aimed to explore its effect on SAP.

METHODS

Peripheral blood monocyte cells from the SAP or non-SAP patients, as well as bone marrow-derived macrophages from wild-type, TRIM29 -/- , or stimulator of interferon genes (STING) -/- mice after injecting 50 mg/kg of cerulein to induce SAP, were isolated to analyze the role of TRIM29 and STING in the SAP.

RESULTS

Tripartite motif-containing protein 29 was significantly reduced in SAP patients. Compared with wild-type mice, TRIM29 deficiency mice displayed more severe symptom of acute pancreatitis after cerulein injection, which were lost in TRIM29 -/- STING -/- mice. Moreover, interferon and its related genes, as well as STING degradation, were decreased in TRIM29 -/- mice.

CONCLUSIONS

Our study demonstrated that TRIM29 negatively regulated the severity of SAP by degrading STING at its downstream, suggesting that TRIM29 and STING might serve as therapeutic targets for SAP.

Nasopharyngeal Carcinoma and Its Microenvironment: Past, Current, and Future Perspectives

Nasopharyngeal carcinoma (NPC) is an epithelial malignancy that raises public health concerns in endemic countries. Despite breakthroughs in therapeutic strategies, late diagnosis and drug resistance often lead to unsatisfactory clinical outcomes in NPC patients. The tumor microenvironment (TME) is a complex niche consisting of tumor-associated cells, such as fibroblasts, endothelial cells, leukocytes, that influences tumor initiation, progression, invasion, and metastasis. Cells in the TME communicate through various mechanisms, of note, exosomes, ligand-receptor interactions, cytokines and chemokines are active players in the construction of TME, characterized by an abundance of immune infiltrates with suppressed immune activities. The NPC microenvironment serves as a target-rich niche for the discovery of potential promising predictive or diagnostic biomarkers and the development of therapeutic strategies. Thus, huge efforts have been made to exploit the role of the NPC microenvironment. The whole picture of the NPC microenvironment remains to be portrayed to understand the mechanisms underlying tumor biology and implement research into clinical practice. The current review discusses the recent insights into the role of TME in the development and progression of NPC which results in different clinical outcomes of patients. Clinical interventions with the use of TME components as potential biomarkers or therapeutic targets, their challenges, and future perspectives will be introduced. This review anticipates to provide insights to the researchers for future preclinical, translational and clinical research on the NPC microenvironment.

Modulation of Type I Interferon Responses to Influence Tumor-Immune Cross Talk in PDAC

Immunotherapy has revolutionized the treatment of many cancer types. However, pancreatic ductal adenocarcinomas (PDACs) exhibit poor responses to immune checkpoint inhibitors with immunotherapy-based trials not generating convincing clinical activity. PDAC tumors often have low infiltration of tumor CD8+ T cells and a highly immunosuppressive microenvironment. These features classify PDAC as immunologically "cold." However, the presence of tumor T cells is a favorable prognostic feature in PDAC. Intrinsic tumor cell properties govern interactions with the immune system. Alterations in tumor DNA such as genomic instability, high tumor mutation burden, and/or defects in DNA damage repair are associated with responses to both immunotherapy and chemotherapy. Cytotoxic or metabolic stress produced by radiation and/or chemotherapy can act as potent immune triggers and prime immune responses. Damage- or stress-mediated activation of nucleic acid-sensing pathways triggers type I interferon (IFN-I) responses that activate innate immune cells and natural killer cells, promote maturation of dendritic cells, and stimulate adaptive immunity. While PDAC exhibits intrinsic features that have the potential to engage immune cells, particularly following chemotherapy, these immune-sensing mechanisms are ineffective. Understanding where defects in innate immune triggers render the PDAC tumor-immune interface less effective, or how T-cell function is suppressed will help develop more effective treatments and harness the immune system for durable outcomes. This review will focus on the pivotal role played by IFN-I in promoting tumor cell-immune cell cross talk in PDAC. We will discuss how PDAC tumor cells bypass IFN-I signaling pathways and explore how these pathways can be co-opted or re-engaged to enhance the therapeutic outcome.

Galectin-8, cytokines, and the storm

Galectin-8 (Gal-8) belongs to a family of animal lectins that modulate cell adhesion, cell proliferation, apoptosis, and immune responses. Recent studies have shown that mammalian Gal-8 induces in an autocrine and paracrine manner, the expression and secretion of cytokines and chemokines such as RANKL, IL-6, IL-1β, SDF-1, and MCP-1. This involves Gal-8 binding to receptor complexes that include MRC2/uPAR/LRP1, integrins, and CD44. Receptors ligation triggers FAK, ERK, Akt, and the JNK signaling pathways, leading to induction of NF-κB that promotes cytokine expression. Indeed, immune-competent Gal-8 knockout (KO) mice express systemic lower levels of cytokines and chemokines while the opposite is true for Gal-8 transgenic animals. Cytokine and chemokine secretion, induced by Gal-8, promotes the migration of cancer cells toward cells expressing this lectin. Accordingly, Gal-8 KO mice experience reduced tumor size and smaller and fewer metastatic lesions when injected with cancer cells. These observations suggest the existence of a ‘vicious cycle’ whereby Gal-8 expression and secretion promotes the secretion of cytokines and chemokines that further promote Gal-8 expression. This ‘vicious cycle’ could enhance the development of a ‘cytokine storm’ which is a key contributor to the poor prognosis of COVID-19 patients.

TRIM29 in Cutaneous Squamous Cell Carcinoma

Tripartite motif (TRIM) proteins play important roles in a wide range of cell physiological processes, such as signal transduction, transcriptional regulation, innate immunity, and programmed cell death. TRIM29 protein, encoded by the ATDC gene, belongs to the RING-less group of TRIM protein family members. It consists of four zinc finger motifs in a B-box domain and a coiled-coil domain, and makes use of the B-box domain as E3 ubiquitin ligase in place of the RING. TRIM29 was found to be involved in the formation of homodimers and heterodimers in relation to DNA binding; additional studies have also demonstrated its role in carcinogenesis, DNA damage signaling, and the suppression of radiosensitivity. Recently, we reported that TRIM29 interacts with keratins and FAM83H to regulate keratin distribution. Further, in cutaneous SCC, the expression of TRIM29 is silenced by DNA methylation, leading to the loss of TRIM29 and promotion of keratinocyte migration. This paper reviews the role of TRIM family proteins in malignant tumors, especially the role of TRIM29 in cutaneous SCC.

CircIL4R activates the PI3K/AKT signaling pathway via the miR-761/TRIM29/PHLPP1 axis and promotes proliferation and metastasis in colorectal cancer

BACKGROUND

Accumulating studies have revealed that aberrant expression of circular RNAs (circRNAs) is widely involved in the tumorigenesis and progression of malignant cancers, including colorectal cancer (CRC). Nevertheless, the clinical significance, levels, features, biological function, and molecular mechanisms of novel circRNAs in CRC remain largely unexplored.

METHODS

CRC-related circRNAs were identified through bioinformatics analysis and verified in clinical specimens by qRT-PCR and in situ hybridization (ISH). Then, in vitro and in vivo experiments were performed to determine the clinical significance of, functional roles of, and clinical characteristics associated with circIL4R in CRC specimens and cells. Mechanistically, RNA pull-down, fluorescence in situ hybridization (FISH), luciferase reporter, and ubiquitination assays were performed to confirm the underlying mechanism of circIL4R.

RESULTS

CircIL4R was upregulated in CRC cell lines and in sera and tissues from CRC patients and was positively correlated with advanced clinicopathological features and poor prognosis. Functional experiments demonstrated that circIL4R promotes CRC cell proliferation, migration, and invasion via the PI3K/AKT signaling pathway. Mechanistically, circIL4R was regulated by TFAP2C and competitively interacted with miR-761 to enhance the expression of TRIM29, thereby targeting PHLPP1 for ubiquitin-mediated degradation to activate the PI3K/AKT signaling pathway and consequently facilitate CRC progression.

CONCLUSIONS

Our findings demonstrate that upregulation of circIL4R plays an oncogenic role in CRC progression and may serve as a promising diagnostic and prognostic biomarker for CRC detection and as a potential therapeutic target for CRC treatment.

Myeloid-derived suppressor cells as immunosuppressive regulators and therapeutic targets in cancer

Myeloid-derived suppressor cells (MDSCs) are a heterogenic population of immature myeloid cells with immunosuppressive effects, which undergo massive expansion during tumor progression. These cells not only support immune escape directly but also promote tumor invasion via various non-immunological activities. Besides, this group of cells are proved to impair the efficiency of current antitumor strategies such as chemotherapy, radiotherapy, and immunotherapy. Therefore, MDSCs are considered as potential therapeutic targets for cancer therapy. Treatment strategies targeting MDSCs have shown promising outcomes in both preclinical studies and clinical trials when administrated alone, or in combination with other anticancer therapies. In this review, we shed new light on recent advances in the biological characteristics and immunosuppressive functions of MDSCs. We also hope to propose an overview of current MDSCs-targeting therapies so as to provide new ideas for cancer treatment.

Association of Galectin 9 Expression with Immune Cell Infiltration, Programmed Cell Death Ligand-1 Expression, and Patient's Clinical Outcome in Triple-Negative Breast Cancer

Galectin-9 (Gal-9) is an immune checkpoint protein that facilitates T cell exhaustion and modulates the tumor-associated microenvironment, and could be a potential target for immune checkpoint inhibition. This study was conducted to assess Gal-9 expression in triple-negative breast cancer (TNBC) and evaluate its association with programmed cell death ligand 1 (PD-L1) expression and immune cell infiltration in tumors and the clinical outcome of patients. Overall, 109 patients with TNBC were included. Gal-9 expression was assessed its relationships with tumor clinicopathologic characteristics, tumor-infiltrating lymphocyte (TIL) levels, PD-L1+ immune cells, and tumor cells by tissue microarray and immunohistochemistry. Low Gal-9 expression was statistically correlated with higher tumor stage (p = 0.031) and presence of lymphovascular invasion (p = 0.008). High Gal-9 expression was associated with a high level of stromal TILs (sTIL; p = 0.011) and positive PD-L1 expression on tumor cells (p = 0.004). In survival analyses, low Gal-9 expression was associated with significantly poor OS (p = 0.013) in patients with TNBC with PD-L1 negativity in tumor cells. Our findings suggest that increased Gal-9 expression is associated with changes in the antitumor microenvironment, such as increased immune cell infiltration and antimetastatic changes. This study emphasizes the predictive value and promising clinical applications of Gal-9 in TNBC.