Dexamethasone suppresses immune evasion by inducing GR/STAT3 mediated downregulation of PD-L1 and IDO1 pathways

Drug-induced senescence by aurora kinase inhibitors attenuates innate immune response of macrophages on gastric cancer organoids

Diffuse-type gastric cancer (DGC) is a subtype of gastric cancer with aggressiveness and poor prognosis. It is of great significance to find sensitive drugs for DGC. In the current study, a total of 20 patient-derived organoids (PDOs) were analyzed for screening the therapeutic efficacy of small molecule kinases inhibitors on gastric cancers, especially the therapeutic difference between intestinal-type gastric cancer (IGCs) and DGCs. The IGCs are sensitive to multiple kinases inhibitors, while DGCs are resistant to most of these kinases inhibitors. It was found that DGCs showed drug-induced senescent phenotype after treatment by aurora kinases inhibitors (AURKi) Barasertib-HQPA and Danusertib. The cell diameter of cancer cells are increased with stronger staining of senescence-associated β-galactosidase (SA-β-GAL), and characteristic appearance of multinucleated giant cells. The senescent cancer cells secrete large amounts of chemokine MCP-1/CCL2, which recruit and induce macrophage to M2-type polarization in PDOs of DGC (DPDOs)-macrophage co-culture system. The up-regulation of local MCP-1/CCL2 can interact with MCP-1/CCL2 receptor (CCR2) expressed on macrophages and suppress their innate immunity to cancer cells. Overall, the special response of DGC to AURKi suggests that clinicians should select a sequential therapy with senescent cell clearance after AURKi treatment for DGC.

Paired organoids from primary gastric cancer and lymphatic metastasis are useful for personalized medicine

BACKGROUND

Organoids are approved by the US FDA as an alternative to animal experiments to guide drug development and for sensitivity screening. Stable organoids models of gastric cancer are desirable for personalized medicine and drug screening.

METHODS

Tumor tissues from a primary cancer of the stomach and metastatic cancer of the lymph node were collected for 3D culture. By long-term culture for over 50 generations in vitro, we obtained stably growing organoid lines. We analyzed short tandem repeats (STRs) and karyotypes of cancer cells, and tumorigenesis of the organoids in nude mice, as well as multi-omics profiles of the organoids. A CCK8 method was used to determine the drugs sensitivity to fluorouracil (5-Fu), platinum and paclitaxel.

RESULTS

Paired organoid lines from primary cancer (SPDO1P) and metastatic lymph node (SPDO1LM) were established with unique STRs and karyotypes. The organoid lines resulted in tumorigenesis in vivo and had clear genetic profiles. Compared to SPDO1P from primary cancer, upregulated genes of SPDO1LM from the metastatic lymph node were enriched in pathways of epithelial-mesenchymal transition and angiogenesis with stronger abilities of cell migration, invasion, and pro-angiogenesis. Based on drug sensitivity analysis, the SOX regimen (5-Fu plus oxaliplatin) was used for chemotherapy with an optimal clinical outcome.

CONCLUSIONS

The organoid lines recapitulate the drug sensitivity of the parental tissues. The paired organoid lines present a step-change toward living biobanks for further translational usage.

Increased expression of the kynurenine pathway in mice with eosinophilic meningitis caused by Angiostrongylus cantonensis infection

Angiostrongylus cantonensis is the major cause of eosinophilic meningitis worldwide. The imbalance of neurotoxic and neuroprotective metabolites in the kynurenine pathway (KP) have been suggested to contribute to the pathogenesis of central nervous system (CNS) infection. We hypothesized that KP may also be involved in parasitic eosinophilic meningitis. BALB/c mice were orally infected with 40 A. cantonensis L3, intraperitoneal dexamethasone at a dose of 500 µg/kg/day was administered from the seventh day of infection until the end of the study. The Evans blue method was used to analyze blood-brain barrier (BBB) dysfunction, and indoleamine 2,3-dioxygenase (IDO) proteins levels was measured by Western blot, immunohistochemistry (IHC), and immunofluorescence. Tryptophan and kynurenine concentrations were analyzed by IHC and liquid chromatography-tandem mass spectrometry (LC-MS/MS). The concentrations of Evans blue, IDO, tryptophan and kynurenine in the different groups of mice were compared using the nonparametric Kruskal-Wallis test. BBB dysfunction was found in mice with eosinophilic meningitis. The administration of dexamethasone significantly decreased the amount of Evans blue. An increased IDO expression was shown in Western blot, IHC and immunofluorescence following 2-3 weeks infection. Increased tryptophan and kynurenine expressions in the brain and cerebrospinal fluid (CSF) were also found in IHC and LC-MS/MS studies. The administration of dexamethasone significantly decreased the amount of IDO, tryptophan and kynurenine. In conclusion, A. cantonensis infection inducing BBB damage, then increased the influx of tryptophan into CSF. The administration of dexamethasone significantly decreased the amount of IDO, tryptophan and kynurenine.

Applications and evolution of 3D cancer-immune cell models

Understanding the highly complex tumor-immune landscape is an important goal for developing novel immune therapies for solid cancers. To this end, 3D cancer-immune models have emerged as patient-relevant in vitro tools for modeling the tumor-immune landscape and the cellular interactions within it. In this review, we provide an overview of the components and applications of 3D cancer-immune models and discuss their evolution from 2015 to 2023. Specifically, we observe trends in primary cell-sourced, T cell-based complex models used for therapy evaluation and biological discovery. Finally, we describe the challenges of implementing 3D cancer-immune models and the opportunities for maximizing their potential for deciphering the complex tumor-immune microenvironment and identifying novel, clinically relevant drug targets.

Quercetin exerts anti-tumor immune mechanism by regulating IL-6/JAK2/STAT3 signaling pathway to deplete Treg cells

Breast cancer is still the leading cause of death among women worldwide. Due to the lack of effective drug targets, triple-negative breast cancer has a worse prognosis and higher mortality compared with other types of breast cancer, and chemotherapy is still the main treatment for triple-negative breast cancer at present. Quercetin (QUE) is a flavonoid compound found in a variety of fruits and vegetables. The mechanism of QUE has been extensively studied, such as prostate cancer, colon cancer, ovarian cancer, etc. However, the anti-tumor immune mechanism of QUE in triple-negative breast cancer remains unclear. Therefore, we assessed the anti-tumor immune effects of QUE on triple-negative breast cancer using both 4T1 cells and a xenograft mouse model of 4T1 cells. In vitro, we examined the inhibitory effects of QUE on 4T1 cells and its molecular mechanisms through MTT, Transwell, ELISA, and Western blotting. In vivo, by establishing a xenograft mouse model, we utilized flow cytometry, immunohistochemistry, ELISA, and Western blotting to evaluate the anti-tumor immune effects of QUE on triple-negative breast cancer. The results indicate that QUE inhibits the proliferation, migration, and invasion of 4T1 cells, concurrently significantly suppressing the IL-6/JAK2/STAT3 signaling pathway. Furthermore, it depletes Treg cell content in 4T1 xenograft mice, thereby improving the tumor immune microenvironment and promoting the cytotoxicity of relevant tumor immune cells. These findings suggest that QUE may serve as a potential adjuvant for immune therapy in triple-negative breast cancer.

Association between Metabolic Reprogramming and Immune Regulation in Digestive Tract Tumors

BACKGROUND

The cancers of the digestive tract, including colorectal cancer (CRC), gastric cancer, and esophageal cancer, are part of the most common cancers as well as one of the most important leading causes of cancer death worldwide.

SUMMARY

Despite the emergence of immune checkpoint inhibitors (e.g., anti-CTLA-4 and anti-PD-1/PD-L1) in the past decade, offering renewed optimism in cancer treatment, only a fraction of patients derive benefit from these therapies. This limited efficacy may stem from tumor heterogeneity and the impact of metabolic reprogramming on both tumor cells and immune cells within the tumor microenvironment (TME). The metabolic reprogramming of glucose, lipids, amino acids, and other nutrients represents a pivotal hallmark of cancer, serving to generate energy, reducing equivalent and biological macromolecule, thereby fostering tumor proliferation and invasion. Significantly, the metabolic reprogramming of tumor cells can orchestrate changes within the TME, rendering patients unresponsive to immunotherapy.

KEY MESSAGES

In this review, we predominantly encapsulate recent strides on metabolic reprogramming among digestive tract cancer, especially CRC, in the TME with a focus on how these alterations influence anti-tumor immunity. Additionally, we deliberate on potential strategies to address these abnormities in metabolic pathways and the viability of combined therapy within the realm of anti-cancer immunotherapy.

The cancer-immune dialogue in the context of stress

Although there is little direct evidence supporting that stress affects cancer incidence, it does influence the evolution, dissemination and therapeutic outcomes of neoplasia, as shown in human epidemiological analyses and mouse models. The experience of and response to physiological and psychological stressors can trigger neurological and endocrine alterations, which subsequently influence malignant (stem) cells, stromal cells and immune cells in the tumour microenvironment, as well as systemic factors in the tumour macroenvironment. Importantly, stress-induced neuroendocrine changes that can regulate immune responses have been gradually uncovered. Numerous stress-associated immunomodulatory molecules (SAIMs) can reshape natural or therapy-induced antitumour responses by engaging their corresponding receptors on immune cells. Moreover, stress can cause systemic or local metabolic reprogramming and change the composition of the gastrointestinal microbiota which can indirectly modulate antitumour immunity. Here, we explore the complex circuitries that link stress to perturbations in the cancer-immune dialogue and their implications for therapeutic approaches to cancer.

Organoid co-culture models of the tumor microenvironment promote precision medicine

In recent years, the three-dimensional (3D) culture system has emerged as a promising preclinical model for tumor research owing to its ability to replicate the tissue structure and molecular characteristics of solid tumors in vivo. This system offers several advantages, including high throughput, efficiency, and retention of tumor heterogeneity. Traditional Matrigel-submerged organoid cultures primarily support the long-term proliferation of epithelial cells. One solution for the exploration of the tumor microenvironment is a reconstitution approach involving the introduction of exogenous cell types, either in dual, triple or even multiple combinations. Another solution is a holistic approach including patient-derived tumor fragments, air-liquid interface, suspension 3D culture, and microfluidic tumor-on-chip models. Organoid co-culture models have also gained popularity for studying the tumor microenvironment, evaluating tumor immunotherapy, identifying predictive biomarkers, screening for effective drugs, and modeling infections. By leveraging these 3D culture systems, it is hoped to advance the clinical application of therapeutic approaches and improve patient outcomes.

Glucocorticoid activates STAT3 and NF-κB synergistically with inflammatory cytokines to enhance the anti-inflammatory factor TSG6 expression in mesenchymal stem/stromal cells

Glucocorticoid (GC) is essential for maintaining immune homeostasis. While GC is known to regulate the expression of genes related to inflammation in immune cells, the effects of GC, especially in the presence of inflammation, on non-immune cells remain largely unexplored. In particular, the impact of GC on inflammatory cytokine-induced immune modulatory responses of tissue stromal cells is unknown, though it has been widely used to modulate tissue injuries. Here we found that GC could enhance the expression of TSG6, a vital tissue repair effector molecule, in IFNγ and TNFα treated human umbilical cord (UC)-MSCs. NF-κB activation was found to be required for GC-augmented TSG6 upregulation. STAT3, but not STAT1, was also found to be required for the TSG6 upregulation in MSCs exposed to IFNγ, TNFα and GC. Moreover, the phosphorylation (activation) of STAT3 was attenuated when NF-κB was knocked down. Importantly, human UC-MSCs pretreated with a cocktail containing GC, IFNγ, and TNFα could significantly enhance the therapeutic effect of human UC-MSCs in an acute lung injury mouse model, as reflected by reduced infiltration of immune cells and down-regulation of iNOS in macrophages in the lung. Together, the findings reveal a novel link between GR, NF-κB and STAT3 in regulating the immunomodulatory and regenerative properties of MSCs, providing novel information for the understanding and treatment of inflammatory conditions.

Benchmark for establishment of organoids from gastrointestinal epithelium and cancer based on available consumables and reagents

Gastrointestinal cancers are a public health problem that threatens the lives of human being. A good experimental model is a powerful tool to promote the uncovering pathogenesis and establish novel treatment methods. High-quality biomedical research requires experimental models to recapitulate the physiological and pathological states of their parental tissues as much as possible. Organoids are such experimental models. Organoids refer to small organ-like cellular clusters formed by the expansion and passaging of living tissues in 3D culture medium in vitro. Organoids are highly similar to the original tissues in terms of cellular composition, cell functions, and genomic profiling. Organoids have many advantages, such as short preparation cycles, long-term storage based on cryopreservation, and reusability. In recent years, researchers carried out the establishment of organoids from gastrointestinal mucosa and cancer tissues, and accumulated valuable experiences. In order to promote effective usage and further development of organoid-related technologies in the research of gastrointestinal diseases, this study proposes a benchmark based on utilization of available experimental consumables and reagents, which are involved in the key steps such as collection and pretreatment of biospecimen, organoid construction, organoid cryopreservation and recovery, growth status evaluation, and organoid quality control. We believe that the standard for the construction and preservation of organoids derived from human gastrointestinal epithelium and cancer tissues can provide an important reference for the majority of scientific researchers.

Targeting anticancer immunity in oral cancer: Drugs, products, and nanoparticles

Oral cavity carcinomas are the most frequent malignancies among head and neck malignancies. Oral tumors include not only oral cancer cells with different potency and stemness but also consist of diverse cells, containing anticancer immune cells, stromal and also immunosuppressive cells that influence the immune system reactions. The infiltrated T and natural killer (NK) cells are the substantial tumor-suppressive immune compartments in the tumor. The infiltration of these cells has substantial impacts on the response of tumors to immunotherapy, chemotherapy, and radiotherapy. Nevertheless, cancer cells, stromal cells, and some other compartments like regulatory T cells (Tregs), macrophages, and myeloid-derived suppressor cells (MDSCs) can repress the immune responses against malignant cells. Boosting anticancer immunity by inducing the immune system or repressing the tumor-promoting cells is one of the intriguing approaches for the eradication of malignant cells such as oral cancers. This review aims to concentrate on the secretions and interactions in the oral tumor immune microenvironment. We review targeting tumor stroma, immune system and immunosuppressive interactions in oral tumors. This review will also focus on therapeutic targets and therapeutic agents such as nanoparticles and products with anti-tumor potency that can boost anticancer immunity in oral tumors. We also explain possible future perspectives including delivery of various cells, natural products and drugs by nanoparticles for boosting anticancer immunity in oral tumors.

Dex-Benchmark: datasets and code to evaluate algorithms for transcriptomics data analysis

Many tools and algorithms are available for analyzing transcriptomics data. These include algorithms for performing sequence alignment, data normalization and imputation, clustering, identifying differentially expressed genes, and performing gene set enrichment analysis. To make the best choice about which tools to use, objective benchmarks can be developed to compare the quality of different algorithms to extract biological knowledge maximally and accurately from these data. The Dexamethasone Benchmark (Dex-Benchmark) resource aims to fill this need by providing the community with datasets and code templates for benchmarking different gene expression analysis tools and algorithms. The resource provides access to a collection of curated RNA-seq, L1000, and ChIP-seq data from dexamethasone treatment as well as genetic perturbations of its known targets. In addition, the website provides Jupyter Notebooks that use these pre-processed curated datasets to demonstrate how to benchmark the different steps in gene expression analysis. By comparing two independent data sources and data types with some expected concordance, we can assess which tools and algorithms best recover such associations. To demonstrate the usefulness of the resource for discovering novel drug targets, we applied it to optimize data processing strategies for the chemical perturbations and CRISPR single gene knockouts from the L1000 transcriptomics data from the Library of Integrated Network Cellular Signatures (LINCS) program, with a focus on understudied proteins from the Illuminating the Druggable Genome (IDG) program. Overall, the Dex-Benchmark resource can be utilized to assess the quality of transcriptomics and other related bioinformatics data analysis workflows. The resource is available from: https://maayanlab.github.io/dex-benchmark.

Mechanism of M2 type macrophage-derived extracellular vesicles regulating PD-L1 expression via the MISP/IQGAP1 axis in hepatocellular carcinoma immunotherapy resistance

BACKGROUND

Hepatocellular carcinoma (HCC) is a prevailing cancer affecting human health. M2 macrophages are essential in mediating immune responses in tumors. This study investigated the action of M2 macrophages in immune escape of HCC.

METHODS

Mitotic spindle positioning (MISP), IQ motif containing GTPase activating protein 1 (IQGAP1) and programmed cell death-1 (PD-L1) levels in primary HCC/tumor-adjacent tissues were determined by Western blot, followed by correlation analysis. M2 macrophage and CD3+CD8+T cell percentages were estimated by flow cytometry. Hep3B and HepG2 cells were treated with M2 macrophage conditioned medium (M2-CM) and M2 macrophage-derived extracellular vesicles (M2-EVs) and/or co-cultured with CD8+T cells, followed by assessment of cell viability and apoptosis. TNF-α and INF-γ levels were measured by ELISA. MISP and IQGAP1 overexpression plasmids were transfected into HCC cells to explore their role in immune escape. The interactions among MISP, IQGAP1, STAT3, and PD-L1 were analyzed by co-immunoprecipitation. The mechanism of M2-EVs in HCC immune escape was verified in nude mice.

RESULTS

MISP/IQGAP1/PD-L1 were upregulated in HCC tissues. MISP negatively-correlated with IQGAP1/PD-L1 and IQGAP1 positively-correlated with PD-L1. M2 macrophages were reduced but CD8+T cells were increased in HCC tissues with high MISP expression. M2-CM or M2-EVs inhibited the killing ability of CD8+T cells, increased HCC cell viability, impeded HCC cell apoptosis, induced CD8+T cell apoptosis, downregulated TNF-α and INF-γ, and upregulated PD-L1. M2-EVs facilitated HCC cell immune escape by potentiating IQGAP1 nuclear translocation and activating STAT3 phosphorylation through MISP downregulation. In vivo experiments further verified the action of M2-EVs through MISP.

CONCLUSION

M2-EVs promote HCC cell immune escape by upregulating PD-L1 through the MISP/IQGAP1/STAT3 axis.

Survival Among Veterans Receiving Steroids for Immune-Related Adverse Events After Immune Checkpoint Inhibitor Therapy

Importance

Systemic steroids are commonly used to manage immune-related adverse events (irAEs), but it remains unclear whether they may undermine immune checkpoint inhibitor (ICI) therapy outcomes. Few studies have assessed the impact of steroid timing and its association with continuation or cessation of ICI therapy.

Objective

To characterize how systemic steroids and steroid timing for irAEs are associated with survival in patients receiving ICI therapy.

Design, Setting, and Participants

This multicenter retrospective cohort study encompassed veterans receiving ICI for cancer between January 1, 2010, and December 31, 2021. Data analysis was conducted September 8, 2023.

Exposures

Identifiable primary diagnosis of cancer. Patients were categorized into 3 cohorts: those receiving no steroids, systemic steroids for irAEs, and steroids for non-irAE-associated reasons. All eligible patients received 1 or more doses of an ICI (atezolizumab, avelumab, cemiplimab, durvalumab, ipilimumab, nivolumab, or pembrolizumab). Eligible patients in the steroid group received at least 1 dose (intravenous, intramuscular, or oral) of dexamethasone, hydrocortisone, methylprednisolone, prednisone, or prednisolone. Steroid use at baseline for palliation or infusion prophylaxis or delivered as a single dose was deemed to be non-irAE associated. All other patterns of steroid use were assumed to be for irAEs.

Main Outcomes and Measures

The primary outcome was overall survival, with a 5-year follow-up after ICI initiation. Kaplan-Meier survival analyses were performed with pairwise log-rank tests to determine significance. Risk was modeled with Cox proportional hazard regression.

Results

The cohort consisted of 20 163 veterans receiving ICI therapy including 12 221 patients (mean [SD] age, 69.5 [8.0] years; 11 830 male patients [96.8%]; 9394 White patients [76.9%]) who received systemic steroids during ICI treatment and 7942 patients (mean [SD] age, 70.3 [8.5] years; 7747 male patients [97.5%]; 6085 White patients [76.6%]) who did not. Patients with an irAE diagnosis had significantly improved overall survival (OS) compared with those without (median [IQR] OS, 17.4 [6.6 to 48.5] months vs 10.5 [3.5 to 36.8] months; adjusted hazard ratio, 0.84; 95% CI, 0.81-0.84; P < .001). For patients with irAEs, systemic steroids for irAEs were associated with significantly improved survival compared with those who received steroids for non-irAE-related reasons or no steroid treatment (median [IQR] OS, 21.3 [9.3 to 58.2] months vs 13.6 [5.5 to 33.7] months vs 15.8 [4.9 to not reached] months; P <.001). However, among those who received steroids for irAEs, early steroid use (<2 months after ICI initiation) was associated with reduced relative survival benefit vs later steroid use, regardless of ICI continuation or cessation following steroid initiation (median [IQR] OS after ICI cessation 4.4 [1.9 to 19.5] months vs 16.0 [8.0 to 42.2] months; median [IQR] OS after ICI continuation, 16.0 [7.1 to not reached] months vs 29.2 [16.5 to 53.5] months; P <.001).

Conclusions and Relevance

This study suggests that steroids for irAE management may not abrogate irAE-associated survival benefits. However, early steroid administration within 2 months of ICI initiation is associated with shorter survival despite continuation of ICI therapy.

Pleckstrin-2 promotes tumour immune escape from NK cells by activating the MT1-MMP-MICA signalling axis in gastric cancer

Immune escape is a major challenge in tumour immunotherapy. Pleckstrin-2(PLEK2) plays a critical role in tumour progression, but its role in immune escape in gastric cancer (GC) remains uncharacterized. RNA sequencing was used to explore the differentially expressed genes in a GC cell line that was resistant to the antitumor effect of Natural killer (NK) cells. Apoptosis and the expression of IFN-γ and TNF-α were detected by flow cytometry (FCM). PLEK2 expression was examined by Western blotting and immunohistochemistry (IHC). PLEK2 was upregulated in MGC803R cells that were resistant to the antitumor effect of NK cells. PLEK2 knockout increased the sensitivity of GC cells to NK cell killing. PLEK2 expression was negatively correlated with MICA and positively correlated with MT1-MMP expression both in vitro and in vivo. PLEK2 promoted Sp1 phosphorylation through the PI3K-AKT pathway, thereby upregulating MT1-MMP expression, which ultimately led to MICA shedding. In mouse xenograft models, PLEK2 knockout inhibited intraperitoneal metastasis of GC cells and promoted NK cell infiltration. In summary, PLEK2 suppressed NK cell immune surveillance by promoting MICA shedding, which serves as a potential therapeutic target for GC.

The identification of genes associated T-cell exhaustion and construction of prognostic signature to predict immunotherapy response in lung adenocarcinoma

T-cell exhaustion (Tex) is considered to be a reason for immunotherapy resistance and poor prognosis in lung adenocarcinoma. Therefore, we used weighted correlation network analysis to identify Tex-related genes in the cancer genome atlas (TCGA). Unsupervised clustering approach based on Tex-related genes divided patients into cluster 1 and cluster 2. Then, we utilized random forest and the least absolute shrinkage and selection operator to identify nine key genes to construct a riskscore. Patients were classified as low or high-risk groups. The multivariate cox analysis showed the riskscore was an independent prognostic factor in TCGA and GSE72094 cohorts. Moreover, patients in cluster 2 with high riskscore had the worst prognosis. The immune response prediction analysis showed the low-risk group had higher immune, stromal, estimate scores, higher immunophenscore (IPS), and lower tumor immune dysfunction and exclusion score which suggested a better response to immune checkpoint inhibitors (ICIs) therapy in the low-risk group. In the meantime, we included two independent immunotherapy cohorts that also confirmed a better response to ICIs treatment in the low-risk group. Besides, we discovered differences in chemotherapy and targeted drug sensitivity between two groups. Finally, a nomogram was built to facilitate clinical decision making.

The opportunities and challenges in immunotherapy: Insights from the regulation of PD-L1 in cancer cells

The immunosuppressive molecule programmed death-ligand 1 (PD-L1) is frequently upregulated in human cancers. Binding of PD-L1 to its receptor, programmed death-1 (PD-1), on activated T cells facilitates cancer cells to evade the host immune system. Antibody-based PD-1/PD-L1 inhibitors can inhibit PD-1/PD-L1 interaction allowing reactivate cytotoxic T cells to eradicate advanced cancer cells. However, the majority of cancer patients fail to respond to anti-PD-1/PD-L1 therapies and the molecular mechanisms for this remain poorly understood. Recent studies show that PD-L1 expression level on tumor cells affect the clinical efficacy of immune checkpoint therapies. Thus, furthering our understanding of the regulatory mechanisms of PD-L1 expression in cancer cells will be critical to improve clinical response rates and the efficacy of PD-1/PD-L1 immune therapies. Here we review recent studies, primarily focusing on the mechanisms that regulate PD-L1 expression at the transcriptional, post-transcriptional and protein level, with the purpose to drive the development of more targeted and effective anti-PD-1/PD-L1 cancer therapies.

Regulation of PD-L1 Expression by Nuclear Receptors

The suppression of excessive immune responses is necessary to prevent injury to the body, but it also allows cancer cells to escape immune responses and proliferate. Programmed cell death 1 (PD-1) is a co-inhibitory molecule that is present on T cells and is the receptor for programmed cell death ligand 1 (PD-L1). The binding of PD-1 to PD-L1 leads to the inhibition of the T cell receptor signaling cascade. PD-L1 has been found to be expressed in many types of cancers, such as lung, ovarian, and breast cancer, as well as glioblastoma. Furthermore, PD-L1 mRNA is widely expressed in normal peripheral tissues including the heart, skeletal muscle, placenta, lungs, thymus, spleen, kidney, and liver. The expression of PD-L1 is upregulated by proinflammatory cytokines and growth factors via a number of transcription factors. In addition, various nuclear receptors, such as androgen receptor, estrogen receptor, peroxisome-proliferator-activated receptor γ, and retinoic-acid-related orphan receptor γ, also regulate the expression of PD-L1. This review will focus on the current knowledge of the regulation of PD-L1 expression by nuclear receptors.

Interactions of IDO and the Kynurenine Pathway with Cell Transduction Systems and Metabolism at the Inflammation-Cancer Interface

The mechanisms underlying a relationship between inflammation and cancer are unclear, but much emphasis has been placed on the role of tryptophan metabolism to kynurenine and downstream metabolites, as these make a substantial contribution to the regulation of immune tolerance and susceptibility to cancer. The proposed link is supported by the induction of tryptophan metabolism by indoleamine-2,3-dioxygenase (IDO) or tryptophan-2,3-dioxygenase (TDO), in response to injury, infection or stress. This review will summarize the kynurenine pathway and will then focus on the bi-directional interactions with other transduction pathways and cancer-related factors. The kynurenine pathway can interact with and modify activity in many other transduction systems, potentially generating an extended web of effects other than the direct effects of kynurenine and its metabolites. Conversely, the pharmacological targeting of those other systems could greatly enhance the efficacy of changes in the kynurenine pathway. Indeed, manipulating those interacting pathways could affect inflammatory status and tumor development indirectly via the kynurenine pathway, while pharmacological modulation of the kynurenine pathway could indirectly influence anti-cancer protection. While current efforts are progressing to account for the failure of selective IDO1 inhibitors to inhibit tumor growth and to devise means of circumventing the issue, it is clear that there are wider factors involving the relationship between kynurenines and cancer that merit detailed consideration as alternative drug targets.

Immunosuppression for immune-related adverse events during checkpoint inhibition: an intricate balance

Immune checkpoint inhibitors (ICIs) have changed perspectives for patients with cancer, but come with severe immune-related adverse events (irAEs). To prevent fatality or chronicity, these irAEs are often promptly treated with high-dose immunosuppressants. Until recently, evidence on the effects of irAE management on ICI efficacy has been sparse. As a result, algorithms for irAE management are mostly expert-opinion based and barely consider possible detrimental effects of immunosuppressants on ICI efficacy. However, recent growing evidence suggests that vigorous immunosuppressive management of irAEs comes with unfavourable effects on ICI efficacy and survival. With expansion of the indications of ICIs, evidence-based treatment of irAEs without hampering tumour control becomes more and more important. In this review, we discuss novel evidence from pre-clinical and clinical studies on the effects of different irAE management regimens including corticosteroids, TNF inhibition and tocilizumab on cancer control and survival. We provide recommendations for pre-clinical research, cohort studies and clinical trials that can help clinicians in tailored irAE management, minimising patients' burden while maintaining ICI efficacy.

Landscapes and mechanisms of CD8+ T cell exhaustion in gastrointestinal cancer

CD8+ T cells, a cytotoxic T lymphocyte, are a key component of the tumor immune system, but they enter a hyporeactive T cell state in long-term chronic inflammation, and how to rescue this depleted state is a key direction of research. Current studies on CD8+ T cell exhaustion have found that the mechanisms responsible for their heterogeneity and differential kinetics may be closely related to transcription factors and epigenetic regulation, which may serve as biomarkers and potential immunotherapeutic targets to guide treatment. Although the importance of T cell exhaustion in tumor immunotherapy cannot be overstated, studies have pointed out that gastric cancer tissues have a better anti-tumor T cell composition compared to other cancer tissues, which may indicate that gastrointestinal cancers have more promising prospects for the development of precision-targeted immunotherapy. Therefore, the present study will focus on the mechanisms involved in the development of CD8+ T cell exhaustion, and then review the landscapes and mechanisms of T cell exhaustion in gastrointestinal cancer as well as clinical applications, which will provide a clear vision for the development of future immunotherapies.

Patient-derived organoids in translational oncology and drug screening

Patient-derived organoids (PDO) are a new biomedical research model that can reconstruct phenotypic and genetic characteristics of the original tissue and are useful for research on pathogenesis and drug screening. To introduce the progression in this field, we review the key factors of constructing organoids derived from epithelial tissues and cancers, covering culture medium and matrix, morphological characteristics, genetic profiles, high-throughput drug screening, and application potential. We also discuss the co-culture system of cancer organoids with tumor microenvironment (TME) associated cells. The co-culture system is widely used in evaluating crosstalk of cancer cells with TME components, such as fibroblasts, endothelial cells, immune cells, and microorganisms. The article provides a prospective for standardized cultivation mode, automatic morphological evaluation, and drug sensitivity screening using high-throughput methods.

Newly developed 3D in vitro models to study tumor-immune interaction

Immunotherapy as a rapidly developing therapeutic approach has revolutionized cancer treatment and revitalized the field of tumor immunology research. 3D in vitro models are emerging as powerful tools considering their feature to maintain tumor cells in a near-native state and have been widely applied in oncology research. The novel 3D culture methods including the co-culture of organoids and immune cells, ALI culture, 3D-microfluidic culture and 3D-bioprinting offer new approaches for tumor immunology study and can be applied in many fields such as personalized treatment, immunotherapy optimizing and adoptive cell therapy. In this review, we introduce commonly used 3D in vitro models and summarize their applications in different aspects of tumor immunology research. We also provide a preliminary analysis of the current shortcomings of these models and the outlook of future development.

Dexamethasone and OLT1177 Cooperate in the Reduction of Melanoma Growth by Inhibiting STAT3 Functions

The NLRP3 inflammasome is a multimolecular complex that processes inactive IL-1β and IL-18 into proinflammatory cytokines. OLT1177 is an orally active small compound that specifically inhibits NLRP3. Here, B16F10 melanoma were implanted in mice and treated with OLT1177 as well as combined with the glucocorticoid dexamethasone. At sacrifice, OLT1177 treated mice had significantly smaller tumors compared to tumor-bearing mice treated with vehicle. However, the combined treatment of OLT1177 plus dexamethasone revealed a greater suppression of tumor growth. This reduction was accompanied by a downregulation of nuclear and mitochondrial STAT3-dependent gene transcription and by a significant reduction of STAT3 Y705 and S727 phosphorylations in the tumors. In vitro, the human melanoma cell line 1205Lu, stimulated with IL-1α, exhibited significantly lower levels of STAT3 Y705 phosphorylation by the combination treatment, thus affecting the nuclear functions of STAT3. In the same cells, STAT3 serine 727 phosphorylation was also lower, affecting the mitochondrial functions of STAT3. In addition, metabolic analyses revealed a marked reduction of ATP production rate and glycolytic reserve in cells treated with the combination of OLT1177 plus dexamethasone. These findings demonstrate that the combination of OLT1177 and dexamethasone reduces tumor growth by targeting nuclear as well as mitochondrial functions of STAT3.

Replication stress identifies novel molecular classification associated with treatment outcomes in pancreatic cancer

BACKGROUND

Replication stress is a prominent hallmark of tumor cells, which is crucial for maintaining genomic integrity. However, it remains poorly understood whether replication stress can serve as a surrogate biomarker to indicate prognosis and treatment response of pancreatic cancer.

METHODS

Transcriptomic and clinical data were obtained from The Cancer Genome Atlas and literature. An integrated signature of 18 replication-stress associated genes (termed as REST18) was established using the cox proportional hazards regression analysis. Tumors were sorted into REST18-low and REST18-high groups. Survival analysis, gene set enrichment analysis and composition of immune cells were compared between these tumors.

RESULTS

Patients with REST18-high tumors showed worse prognoses than those with REST18-low tumors in the TCGA database and the finding is validated in an independent cohort of pancreatic cancer. Comparison of REST18 model and other molecular classifications showed that REST18-high tumors are positively correlated to basal-like or squamous phenotypes, which have higher metastasis potential. DNA repair pathway is enriched in the REST18-high tumors. Analysis of tumor immune microenvironment found that REST18-high tumors are characterized with "immune-cold" features. Univariate and multivariate analysis show that REST18 is an independent risk factor for overall survival and predicts outcomes of chemotherapy in pancreatic cancer.

CONCLUSION

REST18 is a novel biomarker to indicate prognosis and treatment response of chemotherapy in pancreatic cancer.

Impact of endogenous glucocorticoid on response to immune checkpoint blockade in patients with advanced cancer

Background

Previous studies indicate that exogenous use of glucocorticoid (GC) affects immune checkpoint inhibitor (ICI) efficacy. However, there is a paucity of clinical data evaluating the direct impact of endogenous GC on the efficacy for cancer patients with immune checkpoint blockade.

Methods

We first compared the endogenous circulating GC levels in healthy individuals and patients with cancer. We next retrospectively reviewed patients with advanced cancer with PD-1/PD-L1 inhibitor alone or combination therapy in a single center. The effects of baseline circulating GC levels on objective response rate (ORR), durable clinical benefit (DCB), progression-free survival (PFS), and overall survival (OS) were analyzed. The association of the endogenous GC levels with circulating lymphocytes, cytokines levels, and neutrophil to lymphocyte ratio, and tumor infiltrating immune cells, were systematically analyzed.

Results

The endogenous GC levels in advanced cancer patients were higher than those in early-stage cancer patients as well as healthy people. In the advanced cancer cohort with immune checkpoint blockade (n=130), patients with high baseline endogenous GC levels (n=80) had a significantly reduced ORR (10.0% vs 40.0%; p<0.0001) and DCB (35.0% vs 73.5%, p=0.001) compared to those with low endogenous GC levels (n=50). The increased GC levels was significantly associated with reduced PFS (HR 2.023; p=0.0008) and OS (HR 2.809; p=0.0005). Moreover, statistically significant differences regarding PFS, and OS were also detected after propensity score matching. In a multivariable model, the endogenous GC was identified as an independent indicator for predicting PFS (HR 1.779; p=0.012) and OS (HR 2.468; p=0.013). High endogenous GC levels were significantly associated with reduced lymphocytes (p=0.019), increased neutrophil to lymphocyte ratio (p=0.0009), and increased interleukin-6 levels (p=0.025). Patients with high levels of endogenous GC had low numbers of tumor infiltrating CD3⁺ (p=0.001), CD8⁺ T (p=0.059), and CD4⁺ T (p=0.002) cells, and the numbers of circulating PD-1⁺ NK cells (p=0.012), and the ratio of CD8⁺PD-1⁺ to CD4⁺PD-1⁺ (p=0.031) were higher in patients with high levels of endogenous GC compared to low levels of endogenous GC.

Conclusion

Baseline endogenous GC increase executes a comprehensive negative effect on immunosurveillance and response to immunotherapy in real-world cancer patients accompanied with cancer progression.

Tislelizumab for cervical cancer: A retrospective study and analysis of correlative blood biomarkers

Background

Tislelizumab is an anti-programmed cell death 1 (PD-1) monoclonal antibody engineered to minimize binding to Fcγ receptors. It has been used to treat several solid tumors. However, its efficacy and toxicity, and the predictive and prognostic value of baseline hematological parameters in patients with recurrent or metastatic cervical cancer (R/M CC) receiving tislelizumab remain unclear.

Methods

We reviewed 115 patients treated for R/M CC with tislelizumab from March 2020 to June 2022 in our institute. The antitumor activity of tislelizumab was assessed using RECIST v1.1. Associations between the baseline hematological parameters and efficacy of tislelizumab in these patients were analyzed.

Results

With a median follow-up of 11.3 months (range, 2.2-28.7), the overall response rate was 39.1% (95% CI, 30.1-48.2) and the disease control rate was 77.4% (95% CI, 69.6-85.2). The median progression-free survival (PFS) was 19.6 months (95% CI, 10.7 to not reached). The median overall survival (OS) was not reached. Treatment-related adverse events (TRAEs) of any grade occurred in 81.7% of the patients and only 7.0% of the patients experienced grade 3 or 4 TRAEs. Univariate and multivariate regression analyses showed that the level of pretreatment serum C-reactive protein (CRP) was an independent risk factor for the response (complete or partial response) to tislelizumab and the PFS of R/M CC patients treated with tislelizumab (P = 0.0001 and P = 0.002, respectively). R/M CC patients with elevated baseline CRP levels had a short PFS (P = 0.0005). Additionally, the CRP-to-albumin ratio (CAR) was an independent risk factor for the PFS and OS of R/M CC patients treated with tislelizumab (P = 0.001 and P = 0.031, respectively). R/M CC patients with an elevated baseline CAR had short PFS and OS (P < 0.0001 and P = 0.0323, respectively).

Conclusions

Tislelizumab showed promising antitumor activity and tolerable toxicity in patients with R/M CC. The baseline serum CRP levels and CAR showed potential for predicting the efficacy of tislelizumab and the prognosis of R/M CC patients receiving tislelizumab.

CHD4 promotes acquired chemoresistance and tumor progression by activating the MEK/ERK axis

AIMS

Chemoresistance remains a major challenge in gastric cancer (GC). Chromodomain helicase DNA-binding protein 4 (CHD4) mediated chromatin remodeling plays critical roles in various tumor types, but its role in chemoresistance in GC remains uncharacterized.

METHODS

CHD4 expression was examined by immunohistochemistry and Western blotting. The role of CHD4 on cell proliferation and chemoresistance of GC was examined in vitro and in vivo. Immunoprecipitation and liquid chromatography-mass spectrometry were used to identify CHD4-binding proteins and a proximity ligation assay was used to explore protein-protein interaction.

RESULTS

Chemoresistance is associated with upregulation of CHD4 in the tumor tissues of GC patients. Overexpression of CHD4 increased chemoresistance and cell proliferation. Knockdown of CHD4 induced cell apoptosis and cell cycle arrest. CHD4 mediates the decrease of the intracellular concentration of cisplatin by inducing drug efflux. Additionally, CHD4 promotes the interaction between ERK1/2 and MEK1/2, resulting in continuous activation of MEK/ERK pathway. Knockdown of CHD4 in GC increased sensitivity to chemotherapy and suppressed tumor growth in a mouse xenograft model.

CONCLUSIONS

This study identifies CHD4 dominated multi-drug efflux as a promising therapeutic target for overcoming acquired chemoresistance in GC.

The role of IL-6/JAK2/STAT3 signaling pathway in cancers

Interleukin-6 (IL-6) is a pleiotropic cytokine involved in immune regulation. It can activate janus kinase 2 (JAK2)-signal transducer and activator of transcription 3 (STAT3) signaling pathway. As one of the important signal transduction pathways in cells, JAK2/STAT3 signaling pathway plays a critical role in cell proliferation and differentiation by affecting the activation state of downstream effector molecules. The activation of JAK2/STAT3 signaling pathway is involved in tumorigenesis and development. It contributes to the formation of tumor inflammatory microenvironment and is closely related to the occurrence and development of many human tumors. This article focuses on the relationship between IL-6/JAK2/STAT3 signaling pathway and liver cancer, breast cancer, colorectal cancer, gastric cancer, lung cancer, pancreatic cancer and ovarian cancer, hoping to provide references for the research of cancer treatment targeting key molecules in IL-6/JAK2/STAT3 signaling pathway.

Tumor microenvironment-mediated immune tolerance in development and treatment of gastric cancer

Tumor microenvironment is the general term for all non-cancer components and their metabolites in tumor tissue. These components include the extracellular matrix, fibroblasts, immune cells, and endothelial cells. In the early stages of tumors, the tumor microenvironment has a tumor suppressor function. As the tumor progresses, tumor immune tolerance is induced under the action of various factors, such that the tumor suppressor microenvironment is continuously transformed into a tumor-promoting microenvironment, which promotes tumor immune escape. Eventually, tumor cells manifest the characteristics of malignant proliferation, invasion, metastasis, and drug resistance. In recent years, stress effects of the extracellular matrix, metabolic and phenotypic changes of innate immune cells (such as neutrophils, mast cells), and adaptive immune cells in the tumor microenvironment have been revealed to mediate the emerging mechanisms of immune tolerance, providing us with a large number of emerging therapeutic targets to relieve tumor immune tolerance. Gastric cancer is one of the most common digestive tract malignancies worldwide, whose mortality rate remains high. According to latest guidelines, the first-line chemotherapy of advanced gastric cancer is the traditional platinum and fluorouracil therapy, while immunotherapy for gastric cancer is extremely limited, including only Human epidermal growth factor receptor 2 (HER-2) and programmed death ligand 1 (PD-L1) targeted drugs, whose benefits are limited. Clinical experiments confirmed that cytotoxic T-lymphocyte-associated protein 4 (CTLA-4), vascular endothelial growth factor receptor (VEGFR) and other targeted drugs alone or in combination with other drugs have limited efficacy in patients with advanced gastric cancer, far less than in lung cancer, colon cancer, and other tumors. The failure of immunotherapy is mainly related to the induction of immune tolerance in the tumor microenvironment of gastric cancer. Therefore, solving the immune tolerance of tumors is key to the success of gastric cancer immunotherapy. In this study, we summarize the latest mechanisms of various components of the tumor microenvironment in gastric cancer for inducing immune tolerance and promoting the formation of the malignant phenotype of gastric cancer, as well as the research progress of targeting the tumor microenvironment to overcome immune tolerance in the treatment of gastric cancer.

Applications of human organoids in the personalized treatment for digestive diseases

Digestive system diseases arise primarily through the interplay of genetic and environmental influences; there is an urgent need in elucidating the pathogenic mechanisms of these diseases and deploy personalized treatments. Traditional and long-established model systems rarely reproduce either tissue complexity or human physiology faithfully; these shortcomings underscore the need for better models. Organoids represent a promising research model, helping us gain a more profound understanding of the digestive organs; this model can also be used to provide patients with precise and individualized treatment and to build rapid in vitro test models for drug screening or gene/cell therapy, linking basic research with clinical treatment. Over the past few decades, the use of organoids has led to an advanced understanding of the composition of each digestive organ and has facilitated disease modeling, chemotherapy dose prediction, CRISPR-Cas9 genetic intervention, high-throughput drug screening, and identification of SARS-CoV-2 targets, pathogenic infection. However, the existing organoids of the digestive system mainly include the epithelial system. In order to reveal the pathogenic mechanism of digestive diseases, it is necessary to establish a completer and more physiological organoid model. Combining organoids and advanced techniques to test individualized treatments of different formulations is a promising approach that requires further exploration. This review highlights the advancements in the field of organoid technology from the perspectives of disease modeling and personalized therapy.

The LINC00623/NAT10 signaling axis promotes pancreatic cancer progression by remodeling ac4C modification of mRNA

BACKGROUND

Although a substantial increase in the survival of patients with other cancers has been observed in recent decades, pancreatic ductal adenocarcinoma (PDAC) remains one of the deadliest diseases. No effective screening approach exists.

METHODS

Differential exosomal long noncoding RNAs (lncRNAs) isolated from the serum of patients with PDAC and healthy individuals were profiled to screen for potential markers in liquid biopsies. The functions of LINC00623 in PDAC cell proliferation, migration and invasion were confirmed through in vivo and in vitro assays. RNA pulldown, RNA immunoprecipitation (RIP) and coimmunoprecipitation (Co-IP) assays and rescue experiments were performed to explore the molecular mechanisms of the LINC00623/NAT10 signaling axis in PDAC progression.

RESULTS

A novel lncRNA, LINC00623, was identified, and its diagnostic value was confirmed, as it could discriminate patients with PDAC from patients with benign pancreatic neoplasms and healthy individuals. Moreover, LINC00623 was shown to promote the tumorigenicity and migratory capacity of PDAC cells in vitro and in vivo. Mechanistically, LINC00623 bound to N-acetyltransferase 10 (NAT10) and blocked its ubiquitination-dependent degradation by recruiting the deubiquitinase USP39. As a key regulator of N4-acetylcytidine (ac4C) modification of mRNA, NAT10 was demonstrated to maintain the stability of oncogenic mRNAs and promote their translation efficiency through ac4C modification.

CONCLUSIONS

Our data revealed the role of LINC00623/NAT10 signaling axis in PDAC progression, showing that it is a potential biomarker and therapeutic target for PDAC.

Multi-target combinatory strategy to overcome tumor immune escape

Immune therapy has become the fourth approach after surgery, chemotherapy, and radiotherapy in cancer treatment. Many immune checkpoints were identified in the last decade since ipilimumab, which is the first immune checkpoint inhibitor to cytotoxic T-lymphocyte associated protein 4, had been approved by the US Food and Drug Administration (FDA) for the treatment of unresectable or metastatic melanoma in 2011. The use of several antibody drugs that target PD1/PD-L1 for various cancer treatments has been approved by the FDA. However, fewer people are benefitting from immune checkpoint inhibitor treatment in solid cancers. Approximately 80% of patients do not respond appropriately because of primary or acquired therapeutic resistance. Along with the characterization of more immune checkpoints, the combinatory treatment of multiimmune checkpoint inhibitors becomes a new option when monotherapy could not receive a good response. In this work, the author focuses on the combination therapy of multiple immune checkpoints (does not include targeted therapy of oncogenes or chemotherapy), introduces the current progression of multiple immune checkpoints and their related inhibitors, and discusses the advantages of combination therapy, as well as the risk of immune-related adverse events.

Blockade of PD-L1/PD-1 signaling promotes osteo-/odontogenic differentiation through Ras activation

The programmed cell death ligand 1 (PD-L1) and its receptor programmed cell death 1 (PD-1) deliver inhibitory signals to regulate immunological tolerance during immune-mediated diseases. However, the role of PD-1 signaling and its blockade effect on human dental pulp stem cells (hDPSCs) differentiation into the osteo-/odontogenic lineage remain unknown. We show here that PD-L1 expression, but not PD-1, is downregulated during osteo-/odontogenic differentiation of hDPSCs. Importantly, PD-L1/PD-1 signaling has been shown to negatively regulate the osteo-/odontogenic differentiation of hDPSCs. Mechanistically, depletion of either PD-L1 or PD-1 expression increased ERK and AKT phosphorylation levels through the upregulation of Ras enzyme activity, which plays a pivotal role during hDPSCs osteo-/odontogenic differentiation. Treatment with nivolumab (a human anti-PD-1 monoclonal antibody), which targets PD-1 to prevent PD-L1 binding, successfully enhanced osteo-/odontogenic differentiation of hDPSCs through enhanced Ras activity-mediated phosphorylation of ERK and AKT. Our findings underscore that downregulation of PD-L1 expression accompanies during osteo-/odontogenic differentiation, and hDPSCs-intrinsic PD-1 signaling inhibits osteo-/odontogenic differentiation. These findings provide a significant basis that PD-1 blockade could be effective immunotherapeutic strategies in hDPSCs-mediated dental pulp regeneration.

Improvement of the anticancer efficacy of PD-1/PD-L1 blockade via combination therapy and PD-L1 regulation

Immune checkpoint molecules are promising anticancer targets, among which therapeutic antibodies targeting the PD-1/PD-L1 pathway have been widely applied to cancer treatment in clinical practice and have great potential. However, this treatment is greatly limited by its low response rates in certain cancers, lack of known biomarkers, immune-related toxicity, innate and acquired drug resistance, etc. Overcoming these limitations would significantly expand the anticancer applications of PD-1/PD-L1 blockade and improve the response rate and survival time of cancer patients. In the present review, we first illustrate the biological mechanisms of the PD-1/PD-L1 immune checkpoints and their role in the healthy immune system as well as in the tumor microenvironment (TME). The PD-1/PD-L1 pathway inhibits the anticancer effect of T cells in the TME, which in turn regulates the expression levels of PD-1 and PD-L1 through multiple mechanisms. Several strategies have been proposed to solve the limitations of anti-PD-1/PD-L1 treatment, including combination therapy with other standard treatments, such as chemotherapy, radiotherapy, targeted therapy, anti-angiogenic therapy, other immunotherapies and even diet control. Downregulation of PD-L1 expression in the TME via pharmacological or gene regulation methods improves the efficacy of anti-PD-1/PD-L1 treatment. Surprisingly, recent preclinical studies have shown that upregulation of PD-L1 in the TME also improves the response and efficacy of immune checkpoint blockade. Immunotherapy is a promising anticancer strategy that provides novel insight into clinical applications. This review aims to guide the development of more effective and less toxic anti-PD-1/PD-L1 immunotherapies.

PTRF/Cavin-1 as a Novel RNA-Binding Protein Expedites the NF-κB/PD-L1 Axis by Stabilizing lncRNA NEAT1, Contributing to Tumorigenesis and Immune Evasion in Glioblastoma

Background

Immunotherapy, especially checkpoint inhibitors targeting PD-1 or PD-L1, has revolutionized cancer therapy. However, PD-1/PD-L1 inhibitors have not been investigated thoroughly in glioblastoma (GBM). Studies have shown that polymerase 1 and transcript release factor (PTRF/Cavin-1) has an immune-suppressive function in GBM. Thus, the relationship between PTRF and PD-L1 and their role in immune suppression requires further investigation in GBM.

Methods

We used public databases and bioinformatics analysis to investigate the relationship between PTRF and PD-L1. We next confirmed the predicted relationship between PTRF and PD-L1 in primary GBM cell lines by using different experimental approaches. RIP-Seq, RIP, ChIP, and qRT-PCR were conducted to explore the molecular mechanism of PTRF in immunosuppression.

Results

We found that PTRF stabilizes lncRNA NEAT1 to induce NF-κB and PD-L1 and promotes immune evasion in GBM. PTRF was found to correlate with immunosuppression in the public GBM databases. PTRF increased the level of PD-L1 in primary cell lines from GBM patients. We carried out RIP-Seq of GBM cells and found that PTRF interacts with lncRNA NEAT1 and stabilizes its mRNA. PTRF also promoted the activity of NF-κB by suppressing UBXN1 expression via NEAT1 and enhanced the transcription of PD-L1 through NF-κB activation. Finally, PTRF promoted immune evasion in GBM cells by regulating PD-1 binding and PD-L1 mediated T cell cytotoxicity.

Conclusions

In summary, our study identified the PTRF-NEAT1-PD-L1 axis as a novel immune therapeutic target in GBM.

Essential Amino Acid-Enriched Diet Alleviates Dexamethasone-Induced Loss of Muscle Mass and Function through Stimulation of Myofibrillar Protein Synthesis and Improves Glucose Metabolism in Mice

Dexamethasone (DEX) induces dysregulation of protein turnover, leading to muscle atrophy and impairment of glucose metabolism. Positive protein balance, i.e., rate of protein synthesis exceeding rate of protein degradation, can be induced by dietary essential amino acids (EAAs). In this study, we investigated the roles of an EAA-enriched diet in the regulation of muscle proteostasis and its impact on glucose metabolism in the DEX-induced muscle atrophy model. Mice were fed normal chow or EAA-enriched chow and were given daily injections of DEX over 10 days. We determined muscle mass and functions using treadmill running and ladder climbing exercises, protein kinetics using the D₂O labeling method, molecular signaling using immunoblot analysis, and glucose metabolism using a U-¹³C₆ glucose tracer during oral glucose tolerance test (OGTT). The EAA-enriched diet increased muscle mass, strength, and myofibrillar protein synthesis rate, concurrent with improved glucose metabolism (i.e., reduced plasma insulin concentrations and increased insulin sensitivity) during the OGTT. The U-¹³C₆ glucose tracing revealed that the EAA-enriched diet increased glucose uptake and subsequent glycolytic flux. In sum, our results demonstrate a vital role for the EAA-enriched diet in alleviating the DEX-induced muscle atrophy through stimulation of myofibrillar proteins synthesis, which was associated with improved glucose metabolism.

Glucocorticoid and PD-1 Cross-Talk: Does the Immune System Become Confused?

Programmed cell death protein 1 (PD-1) and its ligands, PD-L1/2, control T cell activation and tolerance. While PD-1 expression is induced upon T cell receptor (TCR) activation or cytokine signaling, PD-L1 is expressed on B cells, antigen presenting cells, and on non-immune tissues, including cancer cells. Importantly, PD-L1 binding inhibits T cell activation. Therefore, the modulation of PD-1/PD-L1 expression on immune cells, both circulating or in a tumor microenvironment and/or on the tumor cell surface, is one mechanism of cancer immune evasion. Therapies that target PD-1/PD-L1, blocking the T cell-cancer cell interaction, have been successful in patients with various types of cancer. Glucocorticoids (GCs) are often administered to manage the side effects of chemo- or immuno-therapy, exerting a wide range of immunosuppressive and anti-inflammatory effects. However, GCs may also have tumor-promoting effects, interfering with therapy. In this review, we examine GC signaling and how it intersects with PD-1/PD-L1 pathways, including a discussion on the potential for GC- and PD-1/PD-L1-targeted therapies to "confuse" the immune system, leading to a cancer cell advantage that counteracts anti-cancer immunotherapy. Therefore, combination therapies should be utilized with an awareness of the potential for opposing effects on the immune system.