Gastric Cancer Microenvironment Research Articles

Co-expression pattern of SLC transporter genes associated with the immune landscape and clinical outcomes in gastric cancer.

Solute carrier (SLC) transporters play a dual role in the occurrence and progression of tumours by acting as both suppressors and promoters. However, the overall impact of SLC transcriptome signatures on the tumour microenvironment, biological behaviour and clinical stratification of gastric cancer has not been thoroughly investigated. Therefore, we comprehensively analysed the expression profiles of the SLC transporter family members to identify novel molecular subtypes in gastric cancer. We identified two distinct SLC subtypes, SLC-S1 and SLC-S2, using non-negative matrix factorization. These subtypes were markedly linked with the tumour microenvironment landscape, biological pathway activation and distinct clinical features of gastric cancer. Furthermore, a new scoring model, the SLC score, was developed to quantify the SLC subtypes. High SLC scores indicated a pattern of 'SLC-S2', characterized by stromal infiltration and activation, poor prognosis and insensitivity to chemotherapy and immunotherapy, but high sensitivity to imatinib. The SLC score could serve as a supplement to the Tumour Node Metastasis (TNM) staging system to guide personalized treatment strategies and predict prognosis for patients with gastric cancer.

H. pylori-induced NF-κB-PIEZO1-YAP1-CTGF axis drives gastric cancer progression and cancer-associated fibroblast-mediated tumour microenvironment remodelling.

Gastric cancer (GC) is one of the most common tumours in East Asia countries and is associated with Helicobacter pylori infection. H. pylori utilizes virulence factors, CagA and VacA, to up-regulate pro-inflammatory cytokines and activate NF-κB signaling. Meanwhile, the PIEZO1 upregulation and cancer-associated fibroblast (CAF) enrichment were found in GC progression. However, the mechanisms of PIEZO1 upregulation and its involvement in GC progression have not been fully elucidated. The CAF enrichment and clinical significance were investigated in animal models and primary samples. The expression of NF-κB and PIEZO1 in GC was confirmed by immunohistochemistry staining, and expression correlation was analysed in multiple GC datasets. GSEA and Western blot analysis revealed the YAP1-CTGF axis regulation by PIEZO1. The stimulatory effects of CTGF on CAFs were validated by the co-culture system and animal studies. Patient-derived organoid and peritoneal dissemination models were employed to confirm the role of the PIEZO1-YAP1-CTGF cascade in GC. Both CAF signature and PIEZO1 were positively correlated with H. pylori infection. PIEZO1, a mechanosensor, was confirmed as a direct downstream of NF-κB to promote the transformation from intestinal metaplasia to GC. Mechanistic studies revealed that PIEZO1 transduced the oncogenic signal from NF-κB into YAP1 signaling, a well-documented oncogenic pathway in GC progression. PIEZO1 expression was positively correlated with the YAP1 signature (CTGF, CYR61, and c-Myc, etc.) in primary samples. The secreted CTGF by cancer cells stimulated the CAF infiltration to form a stiffened collagen-enrichment microenvironment, thus activating PIEZO1 to form a positive feedback loop. Both PIEZO1 depletion by shRNA and CTGF inhibition by Procyanidin C1 enhanced the efficacy of 5-FU in suppressing the GC cell peritoneal metastasis. This study elucidates a novel driving PIEZO1-YAP1-CTGF force, which opens a novel therapeutic avenue to block the transformation from precancerous lesions to GC. H. pylori-NF-κB activates the PIEZO1-YAP1-CTGF axis to remodel the GC microenvironment by promoting CAF infiltration. Targeting PIEZO1-YAP1-CTGF plus chemotherapy might serve as a potential therapeutic option to block GC progression and peritoneal metastasis.

Multi-omics characteristics of tumor-associated macrophages in the tumor microenvironment of gastric cancer and their exploration of immunotherapy potential

The incidence and mortality rate of gastric cancer (GC) have remained high worldwide. Although some progress has been made in immunotargeted therapy, the treatment effect remains limited. With more attention has been paid to the immune potential of tumor-associated macrophages (TAMs), but the specific mechanisms of tumor immunity are still unclear. Thus, we screened marker genes in TAMs differentiation (MDMs) through single-cell RNA sequencing, and combined with GC transcriptome data from TCGA and GEO databases, the clinical and TME characteristics, prognostic differences, immune infiltration, and drug sensitivity among different subtypes of patients with GC in different data sets were analyzed. A prognostic model of GC was constructed to evaluate the prognosis and immunotherapy response of patients with GC. In this study, we extensively studied the mutations in MDMs such as CGN, S100A6, and C1QA, and found differences in the infiltration of immune cells and immune checkpoints including M2 TAMs, T cells, CD274, and CTLA4 in different GC subtypes. In the model, we constructed a predictive scoring system with high accuracy and screened out key MDMs-related genes associated with prognosis and M2 TAMs, among which VKORC1 may be involved in GC progression and iron death in tumor cells. Therefore, this study explores the therapeutic strategy of TAMs reprogramming in-depth, providing new ideas for the clinical diagnosis, treatment, and prognosis assessment of GC.

Paracrine activin B-NF-κB signaling shapes an inflammatory tumor microenvironment in gastric cancer via fibroblast reprogramming

BackgroundImportant roles of INHBB in various malignancies are increasingly identified. The underlying mechanisms in gastric cancer (GC) microenvironment are still greatly unexplored.MethodsThe clinical significance of INHBB and the correlation between INHBB and p-p65 in GC were assessed through analyzing publicly available databases and human paraffin embedded GC tissues. The biological crosstalk of INHBB between GC cells and fibroblasts was explored both in vitro and in vivo. RNA-seq analyses were performed to determine the mechanisms which regulating fibroblasts reprogramming. Luciferase reporter assay and chromatin immunoprecipitation (CHIP) assay were used to verify the binding relationship of p65 and INHBB in GC cells.ResultsOur study showed that INHBB level was significantly higher in GC, and that increased INHBB was associated with poor survival. INHBB positively regulates the proliferation, migration, and invasion of GC cells in vitro. Also, activin B promotes the occurrence of GC by reprogramming fibroblasts into cancer-associated fibroblasts (CAFs). The high expression of INHBB in GC cells activates the NF-κB pathway of normal gastric fibroblasts by secreting activin B, and promotes fibroblasts proliferation, migration, and invasion. In addition, activin B activates NF-κB pathway by controlling TRAF6 autoubiquitination to induce TAK1 phosphorylation in fibroblasts. Fibroblasts activated by activin B can induce the activation of p65 phosphorylation of GC cells by releasing pro-inflammatory factors IL-1β. p65 can directly bind to the INHBB promoter and increase the INHBB transcription of GC cells, thus establishing a positive regulatory feedback loop to promote the progression of GC.ConclusionsGC cells p65/INHBB/activin B and fibroblasts p65/IL-1β signal loop led to the formation of a whole tumor-promoting inflammatory microenvironment, which might be a promising therapeutic target for GC.

Correlation of Neuroendocrine Differentiation with a Distinctively Suppressive Immune Microenvironment in Gastric Cancer

Introduction: Neuroendocrine neoplasms (NENs) harbored significantly suppressive tumor immune microenvironments (TIMEs). However, the immunological effects of neuroendocrine differentiation (NED) on non-NENs, such as gastric cancer (GC), were unknown. Methods: Between pure gastric cancer (PGC) and GC-NED, TIME features were scored based on expression data and validated on serial whole-tissue sections of surgical samples, with tertiary lymphoid structures (TLSs) and the extra-TLS zone evaluated independently using multi-marker immunohistochemical staining. Risk analyses of TIME features on tumor behaviors were performed in GC-NED. The universal immunological effects of NED were explored preliminarily in adenocarcinomas arising in other organs. Results: Based on over 11,500 annotated TLSs and 2,700 extra-TLS zones, compared with PGC, GC-NED harbored a distinctively more suppressive TIME characterized by increased but immature TLSs, with higher naïve B-cell and follicular regulatory T-cell densities and downregulated TLS maturation-related cell ratios inside TLSs; increased naïve B-cell and regulatory T-cell densities; and a high proportion of exhausted T cells in the extra-TLS zone. The upregulated tumor PD-L1 expression and its close correlations with TLS formation and maturation were remarkable exclusively in GC-NED. TIME features, especially those regarding TLSs, were significantly correlated with tumor growth and invasion. The desynchrony between TLS formation and maturation and increased naïve or regulatory immune cell infiltration was observed in adenocarcinomas of the colorectum, pancreas, lung, and prostate. Conclusion: NED highlighted a distinct GC entity with more suppressive TIME features correlated with tumor behaviors, indicating a cohort that would benefit more from immunotherapies.

RETRACTED: Hierarchical clustering identifies oxidative stress-related subgroups for the prediction of prognosis and immune microenvironment in gastric cancer

BackgroundGastric cancer (GC) is a prevalent malignancy of the digestive tract globally, demonstrating a substantial occurrence of relapse and metastasis, alongside the absence of efficacious treatment. Tumor progression and the development of cancer are linked to oxidative stress. Our objective was twofold: first, to determine distinct subcategories based on oxidative stress in GC patients, and second, to establish oxidative stress-related genes that would aid in stratifying the risk for GC patients. MethodsTCGA-STAD and GSE84437 datasets were utilized to obtain the mRNA expression profiles and corresponding clinical information of GC patients. Through consensus clustering analysis, distinct subgroups related to oxidative stress were identified. To uncover the underlying mechanisms, GSEA and GSVA were performed. xCell, CIBERSORT, MCPCounter, and TIMER algorithms were employed to evaluate the immune microenvironment and immune status of the different GC subtypes. A prognostic risk model was developed using the TCGA-STAD dataset and substantiated using the GSE84437 dataset. Furthermore, qRT-PCR was employed to validate the expression of genes associated with prognosis. ResultsTwo distinct subtypes of oxidative stress were discovered, with markedly different survival rates. The C1 subtype demonstrated an activated immune signal pathway, a significant presence of immune cell infiltration, high immune score, and a high microenvironment score, indicating a poor prognosis. Moreover, a prognostic signature related to oxidative stress (IMPACT and PXDN) was able to accurately estimate the likelihood of survival for patients with gastric cancer. A nomogram incorporating the patients' gender, age, and risk score was able to predict survival in gastric cancer patients. Additionally, the expression of IMPACT and PXDN showed a strong correlation with overall survival and the infiltration of immune cells. ConclusionBased on signatures related to oxidative stress, we developed an innovative system for categorizing patients with GC. This stratification enables accurate prognostication of individuals with GC.

EFHD1 expression is correlated with tumor-infiltrating neutrophils and predicts prognosis in gastric cancer

BackgroundGastric cancer (GC) ranks third in terms of mortality worldwide. The tumor microenvironment is critical for the progression of gastric cancer. This study investigated the association between EF-hand domain containing 1 (EFHD1) expression and its clinical significance in the tumor microenvironment (TME) of gastric cancer. MethodsWe used bioinformatic analyses to assess the relevance of EFHD1 mRNA in the TME of gastric carcinoma tissues and its relationship with clinical features. Therefore, we performed multiplex immunohistochemistry analyses to determine the potential role of the EFHD1 protein in the TME of gastric cancer. ResultsEFHD1 expression increased dramatically in gastric cancer tissues compared to levels in non-cancerous tissue samples (t = 6.246, P < 0.001). The EFHD1 protein presentation was associated with invasion depth (χ2 = 19.120, P < 0.001) and TNM stages (χ2 = 14.468, P = 0.002). Notably, EFHD1 protein expression was significantly related to CD66b + neutrophil infiltration of the intratumoral (r = 0.420, P < 0.001) and stromal (r = 0.367, P < 0.001) TME in gastric cancer. Additionally, Cox regression analysis revealed that EFHD1 was an independent prognostic predictor (hazard ratio [HR] = 2.262, P < 0.001) in patients with gastric cancer. ConclusionsOur study revealed the pattern of EFHD1 overexpression in the TME of patients with gastric cancer and demonstrated its utility as a biomarker for unfavorable clinical outcomes, thereby providing a potential immunotherapy target.

Prognostic Model and Tumor Immune Microenvironment Analysis of Complement-Related Genes in Gastric Cancer.

The complement system is integral to the innate and adaptive immune response, helping antibodies eliminate pathogens. However, the potential role of complement and its modulators in the tumor microenvironment (TME) of gastric cancer (GC) remains unclear. This study assessed the expression, frequency of somatic mutations, and copy number variations of complement family genes in GC derived from The Cancer Genome Atlas (TCGA). Lasso and Cox regression analyses were conducted to develop a prognostic model based on the complement genes family, with the training and validation sets taken from the TCGA-GC cohort (n=371) and the International Gene Expression Omnibus (GEO) cohort (n=433), correspondingly. The nomogram assessment model was used to predict patient outcomes. Additionally, the link between immune checkpoints, immune cells, and the prognostic model was investigated. In contrast to patients at low risk, those at high risk had a less favorable outcome. The prognostic model-derived risk score was shown to serve as a prognostic marker of GC independently, as per the multivariate Cox analysis. Nomogram assessment showed that the model had high reliability for predicting the survival of patients with GC in the 1, 3, 5 years. Additionally, the risk score was positively linked to the expression of immune checkpoints, notably CTLA4, LAG3, PDCD1, and CD274, according to an analysis of immune processes. The core gene C5aR1 in the prognostic model was found to be upregulated in GC tissues in contrast to adjoining normal tissues, and patients with elevated expressed levels of C5aR1 had lower 10-year overall survival (OS) rates. Our work reveals that complement genes are associated with the diversity and complexity of TME. The complement prognosis model help improves our understanding of TME infiltration characteristics and makes immunotherapeutic strategies more effective.

Study of immunophenotypic characteristics, clinicopathological parameters and prognosis in gastric cancer microenvironment

Objective: To explore the immunophenotypic characteristics of gastric cancer microenvironment and analyze its correlation with clinicopathological parameters and prognosis of patients. Methods: The expression levels of leukocyte differentiation antigen (CD) 8, CD4, T lymphocyte immunoglobulin mucoprotein 3 (TIM3), human forkhead box protein P3 (Foxp3) and co-localized tumor infiltrating lymphocytes (TILs) were detected in 92 cases of gastric cancer tissue [58 males and 34 females; aged M(Q1, Q3), 70(59, 77) years ] and 84 cases of paracancer tissue [57 males and 27 females, aged 70(59, 77) years] purchased from Shanghai Xinchao Biotechnology Co., Ltd., and the samples were from 28 hospitals in the sample bank. Gastric cancer and adjacent tissues were divided into high expression group and low expression group according to the optimal cut-off value of positive lymphocytepercentage. The expression of immunophenotypes in gastric cancer and adjacent tissues was analyzed. Kaplan-Meier method was used for survival analysis. Cox proportional hazard model was used to explore the prognostic factors of gastric cancer patients. Results: The optimal cut-off values of CD8, CD4, TIM3 and Foxp3 positive cells in gastric cancer were 12.73%, 1.39%, 10.77% and 2.44%, respectively. The expression of Foxp3 in gastric cancer tissues was higher than that in paracancer tissues [M (Q1, Q3), 0.93 (0.45, 2.16) vs 0.31 (0.09, 0.86), P<0.001], and the expression of CD8 [4.92 (2.34, 8.80) vs 8.81 (6.61, 12.17), P<0.001], CD4 [4.79 (1.77, 11.36) vs 8.40 (4.84, 12.77), P=0.022] and TIM3 [5.68 (2.05, 11.58) vs 7.07 (3.13, 11.43), P=0.338] were lower than that in paracancer tissues. There were significant differences in TIM3 expression in gastric cancer patients with different lymph node metastasis and clinical stage (all P<0.05). The 5-year survival rate of patients with high CD4 expression, low TIM3 expression and low Foxp3 expression in gastric cancer tissues was poor, among which the high CD4 expression and low CD4 expression groups were 29.3% and 64.7%, respectively; The high and low TIM3 expression groups were 60.9% and 30.4%, respectively; The high and low Foxp3 expression groups were 64.3% and 33.3%, respectively (all P<0.05). The optimal cut-off values of CD8+TIM3+TILs, CD4+TIM3+TILs, CD8+Foxp3+TILs and CD4+Foxp3+TILs were 3.86%, 0.23%, 0.08% and 0.76%, respectively. Colocalization analysis showed that the expression of CD8+Foxp3+TILs in gastric cancer tissues was higher than that in adjacent tissues(all P<0.05). Multivariate Cox regression analysis showed that high expression of CD4 (HR=3.079, 95%CI: 1.350-7.024,P=0.008), low expression of TIM3 (HR=0.428, 95%CI: 0.208-0.879, P=0.021) and low expression of Foxp3 (HR=0.288, 95%CI: 0.121-0.687, P=0.005) were the influencing factor for the 5-year survival rate of patients with gastric cancer after operation. Conclusions: Gastric cancer tissues have complex immune microenvironment characteristics. The expression of CD4, TIM3 and Foxp3 is closely related to the prognosis of patients.

Integrated bioinformatics analysis of noncoding RNAs with tumor immune microenvironment in gastric cancer

In recent years, molecular and genetic research hotspots of gastric cancer have been investigated, including microRNAs, long noncoding RNAs (lncRNAs) and messenger RNA (mRNAs). The study on the role of lncRNAs may help to develop personalized treatment and identify potential prognostic biomarkers in gastric cancer. The RNA-seq and miRNA-seq data of gastric cancer were downloaded from the TCGA database. Differential analysis of RNA expression between gastric cancer samples and normal samples was performed using the edgeR package. The ceRNA regulatory network was visualized using Cytoscape. KEGG pathway analysis of mRNAs in the ceRNA network was performed using the clusterProfiler package. CIBERSORT was used to distinguish 22 immune cell types and the prognosis-related genes and immune cells were determined using Kaplan-Meier and Cox proportional hazard analyses. To estimate these nomograms, we used receiver operating characteristic and calibration curve studies. The ceRNA regulation network of gastric cancer was built in this study, and the genes in the network were analyzed for prognosis. A total of 980 lncRNAs were differentially expressed, of which 774 were upregulated and 206 were downregulated. A survival study identified 15 genes associated with gastric cancer prognosis, including VCAN-AS1, SERPINE1, AL139002.1, LINC00326, AC018781.1, C15orf54, hsa-miR-145. Monocytes and Neutrophils were associated with the survival rate of gastric cancer. Our research uncovers new ceRNA network for the detection, treatment, and monitoring of gastric cancer.

The bioinformatics analysis of CD59 in Helicobacter pylori infected gastric cancer.

Cell surface molecules play important roles in cell signal transduction pathways during microbial infection. In this study, the expression and the functions of CD59 was investigated in H. pylori infected gastric cancer (GC). The differential expression of CD59 and the influence of H. pylori on the expression of CD59 were analyzed via bioinformatics through Gene Set Enrichment in GC. In addition, the expression of CD59 in GES-1, AGS cells and GC tissues infected with H. pylori was confirmed by Western blot. Bioinformatics results and H. pylori infection experiments showed CD59 decreased obviously in H. pylori infected GC cells and tissues. The expression of CD59 was linked to the survival rate of GC patients, and influenced various immune cells in the immune microenvironment of GC. CD59 interacts with other genes to form a network in H. pylori infected GC. Certainly, CD59 decreased significantly in H. pylori infected GC tissues, GES-1 and AGS cells in vitro. H. pylori infection could influence the expression of CD59 in GC indicating that CD59 may be a promising treatment target.

Microdissection of cancer-associated fibroblast infiltration subtypes unveils the secreted SERPINE2 contributing to immunosuppressive microenvironment and immuotherapeutic resistance in gastric cancer: A large-scale study integrating bulk and single-cell transcriptome profiling

In the era of immunotherapy, the suboptimal response rate and the development of acquired resistance among the initial beneficiaries continue to present significant challenges across multiple malignancies, including gastric cancer (GC). Considering that the interactions of tumor stroma, especially the cancer-associated fibroblasts (CAFs), with immune and tumor cells, play indispensable roles in tumor progression, tumor microenvironment remodeling and therapeutic responsiveness, in-depth exploration on the roles of CAFs and pivotal mediators of their functions may provide novel clues to increase the effectiveness of current immunotherapeutic drugs and further achieve synergistic antitumor response. Herein, through the consensus clustering of canonical biomarkers, three GC subclasses with different abundance of CAFs were virtually microdissected in four integrated bulk cohorts encompassing 2148 GC patients from 11 independent datasets. An extensive immunogenomic analysis revealed that tumors with high CAFs infiltration were characterized with unfavorable outcomes, aggressive phenotypes, decreased tumor immunogenicity, high risk of immune evasion and thus immunotherapeutic resistance. By leveraging large-scale single-cell transcriptomic profiling, a series of CAF-secreted proteins were identified, among which the SERPINE2 was confirmed to be restrictively enriched in stromal fibroblasts of GC tissues and contribute to promoting a protumor milieu and fostering an immunosuppressive microenvironment via bioinformatics computations and tissue microarray analysis. Moreover, pan-cancer investigations generalized the immunological roles of SERPINE2, especially in pan-gastrointestinal malignancies, with multiple real-world immunotherapy cohorts further confirming its implications on predicting immunotherapeutic efficacy. In conclusion, these findings suggest that the CAF-derived SERPINE2 is a promising immune-oncology target with therapeutic implications to further synergize the immunotherapeutic combinations.

Construction and validation of a signature for T cell-positive regulators related to tumor microenvironment and heterogeneity of gastric cancer.

Positive regulators of T cell function play a vital role in the proliferation and differentiation of T cells. However, their functions in gastric cancer have not been explored so far. The TCGA-STAD dataset was utilized to perform consensus clustering in order to identify subtypes related to T cell-positive regulators. The prognostic differentially expressed genes of these subtypes were identified using the least absolute shrinkage and selection operator (LASSO) regression analysis. To validate the robustness of the identified signature, verification analyses were conducted across the TCGA-train, TCGA-test, and GEO datasets. Additionally, a nomogram was constructed to enhance the clinical efficacy of this predictive tool. Transwell migration, colony formation, and T cell co-culture assays were used to confirm the function of the signature gene in gastric cancer and its influence on T cell activation. Two distinct clusters of gastric cancer, related to T cell-positive regulation, were discovered through the analysis of gene expression. These clusters exhibited notable disparities in terms of survival rates (P = 0.028), immune cell infiltration (P< 0.05), and response to immunotherapy (P< 0.05). Furthermore, a 14-gene signature was developed to classify gastric cancer into low- and high-risk groups, revealing significant differences in survival rates, tumor microenvironment, tumor mutation burden, and drug sensitivity (P< 0.05). Lastly, a comprehensive nomogram model was constructed, incorporating risk factors and various clinical characteristics, to provide an optimal predictive tool. Additionally, an assessment was conducted on the purported molecular functionalities of low- and high-risk gastric cancers. Suppression of DNAAF3 has been observed to diminish the migratory and proliferative capabilities of gastric cancer, as well as attenuate the activation of T cells induced by gastric cancer within the tumor microenvironment. We identified an ideal prognostic signature based on the positive regulators of T cell function in this study.

Expression patterns and immunological characterization of PANoptosis -related genes in gastric cancer.

Accumulative studies have demonstrated the close relationship between tumor immunity and pyroptosis, apoptosis, and necroptosis. However, the role of PANoptosis in gastric cancer (GC) is yet to be fully understood. This research attempted to identify the expression patterns of PANoptosis regulators and the immune landscape in GC by integrating the GSE54129 and GSE65801 datasets. We analyzed GC specimens and established molecular clusters associated with PANoptosis-related genes (PRGs) and corresponding immune characteristics. The differentially expressed genes were determined with the WGCNA method. Afterward, we employed four machine learning algorithms (Random Forest, Support Vector Machine, Generalized linear Model, and eXtreme Gradient Boosting) to select the optimal model, which was validated using nomogram, calibration curve, decision curve analysis (DCA), and two validation cohorts. Additionally, this study discussed the relationship between infiltrating immune cells and variables in the selected model. This study identified dysregulated PRGs and differential immune activities between GC and normal samples, and further identified two PANoptosis-related molecular clusters in GC. These clusters demonstrated remarkable immunological heterogeneity, with Cluster1 exhibiting abundant immune infiltration. The Support Vector Machine signature was found to have the best discriminative ability, and a 5-gene-based SVM signature was established. This model showed excellent performance in the external validation cohorts, and the nomogram, calibration curve, and DCA indicated its reliability in predicting GC patterns. Further analysis confirmed that the 5 selected variables were remarkably related to infiltrating immune cells and immune-related pathways. Taken together, this work demonstrates that the PANoptosis pattern has the potential as a stratification tool for patient risk assessment and a reflection of the immune microenvironment in GC.

Comprehensive characterization of pyroptosis phenotypes with distinct tumor immune profiles in gastric cancer to aid immunotherapy.

Pyroptosis is a form of programmed cell death that is essential for immunity. Herein, this study was conducted to uncover the implication of pyroptosis in immunomodulation and tumor microenvironment (TME) in gastric cancer. Prognostic pyroptosis-related genes were extracted to identify different pyroptosis phenotypes and pyroptosis genomic phenotypes via unsupervised clustering analysis in the gastric cancer meta-cohort cohort (GSE15459, GSE62254, GSE84437, GSE26253 and TCGA-STAD). The activation of hallmark gene sets was quantified by GSVA and immune cell infiltration was estimated via ssGSEA and CIBERSORT. Through PCA algorithm, pyroptosis score was conducted. The predictors of immune response (TMB and IPS) and genetic mutations were evaluated. The efficacy of pyroptosis score in predicting immune response was verified in two anti-PD-1 therapy cohorts. Three different pyroptosis phenotypes with different prognosis, biological pathways and tumor immune microenvironment were established among 1275 gastric cancer patients, corresponding to three immune phenotypes: immune-inflamed, immune-desert, and immune-excluded. According to the pyroptosis score, patients were separated into high and low pyroptosis score groups. Low pyroptosis score indicated favorable survival outcomes, enhanced immune responses, and increased mutation frequency. Moreover, low pyroptosis score patients displayed more clinical benefits from anti-PD-1 and prolonged survival time. Our findings uncovered a nonnegligible role of pyroptosis in immunomodulation and TME multiformity and complicacy in gastric cancer. Quantifying the pyroptosis score in individual tumors may tailor more effective immunotherapeutic strategies.

CLDN18.2 expression and its impact on prognosis and the immune microenvironment in gastric cancer

BackgroundThe investigational use of zolbetuximab (IMAB362), a groundbreaking monoclonal antibody medication targeting claudin 18.2 (CLDN18.2), for treatment of advanced gastrointestinal cancers is currently underway. The unclear clinicopathological characteristics and tumour immune microenvironment of CLDN18.2-positive gastric cancer (GC) make it difficult to develop and optimize CLDN18.2-targeted therapies.MethodsA total of 451 tumour tissues, 342 matched paraneoplastic tissues, and 107 matched metastatic lymph nodes were collected from GC patients. These specimens were stained for CLDN18.2 expression and quantified using immunohistochemistry (IHC). Correlations between CLDN18.2 expression and clinicopathological features as well as immune-related factors were analysed. Survival curves were drawn using the Kaplan‒Meier approach, and independent factors affecting GC prognosis were identified using Cox regression analysis. Information from relevant databases was used for corroboration.ResultsExpression of the CLDN18.2 gene was significantly lower in gastric tumour tissues than in normal tissues (p < 0.001) but comparable in metastatic lymph nodes (p = 0.851). CLDN18.2 expression was significantly associated with Borrmann type, degree of differentiation, PD-L1 expression, and survival in GC patients and was identified as an independent risk factor for patient prognosis (HR = 1.57, 95% CI 1.16–2.11, p = 0.003). There was no correlation between CLDN18.2 expression and HER2, Lauren type, tumour size, TNM stage, or any other clinicopathological characteristic. In CLDN18.2-positive tumours, fractions of CD4 + T cells and CD8 + T cells were significantly higher than those in CLDN18.2-negative tumours. Patients with CLDN18.2-negative expression and significant CD4 + T-cell or CD8 + T-cell infiltration had the best prognosis (5-year OS: 61.0%, P = 0.036; 5-year OS: 62.2%, P = 0.034).ConclusionsCLDN18.2 is expressed at a low level in tumour tissues and serves as an independent prognostic factor for patients with GC. Furthermore, CLDN18.2 correlates with immune infiltrating cells and PD-L1 expression.

Down-regulation of stimulator of interferon genes (STING) expression and CD8+ T-cell infiltration depending on HER2 heterogeneity in HER2-positive gastric cancer.

HER2 signaling might be involved in the regulation of immune cell activation in the tumor microenvironment (TME) of gastric cancer (GC). However, the relationship between HER2 status and immune cell condition in the HER2-positive GC TME is not clearly understood. To investigate the effect of HER2 signaling on the activation of the cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) pathway, which contributes to immune cell activation in the GC TME, we evaluated the associations among the expressions of HER2, cGAS-STING, and the number of CD8+ tumor-infiltrating lymphocytes (TIL) by considering HER2 heterogeneity in HER2-positive GC tissues. We also examined the effect of HER2 signaling on the activation of STING signaling in vitro using human HER2-positive GC cell lines. The expression of HER2 is highly heterogeneous in HER2-positive GC tissues, and we found that the number of CD8+ TIL in HER2 high areas was significantly lower than that in HER2 low areas in HER2-positive GC tissues. Intriguingly, the tumor cell-intrinsic expression of STING, but not cGAS, was also significantly lower in the HER2 high areas than the HER2 low areas in HER2-positive GC tissues. Moreover, in vitro experiments, we demonstrated that the blockade of HER2 signaling increased the expression of STING and its target genes, including IFNB1, CXCL9/10/11, and CCL5, in HER2-positive GC cell lines. Our results suggest that HER2 signaling might suppress immune cell activation in the GC TME by inhibiting STING signaling in tumor cells in HER2-positive GC.

A Novel Neutrophil Extracellular Traps Signature for Overall Survival Prediction and Tumor Microenvironment Identification in Gastric Cancer.

Neutrophil extracellular traps (NETs) released by neutrophils are crucial for cancer development, metastasis, and can indicate gastric cancer (GC) patients' prognosis. This study reveals the relevance of NETs-related genes to GC through transcriptome analysis. We obtained transcriptome sequencing data of GC from UCSC Xena and screened prognostic NETs-related genes by GEPIA2 database. The signature for NETs was subsequently created using the LASSO-Cox regression. The clinical value of model was further explored using the nomogram and was externally validated by the GEO database. After that, we employed GO, KEGG, and GSEA enrichment analyses to evaluate the bio-functional enrichment and related pathways. Additionally, ESTIMATE, MCP counter, and ssGSEA scores were used to investigate the immunological microenvironment of GC patients. Finally, in the external cohort, neutrophil elastase (NE)-DNA complexes were measured by ELISA, and the prognostic value of NE-DNA in GC was investigated using Cox analysis. Seven NETs-associated genes (PDE4B, CD93, CTSG, IL6, ELANE, KCNJ15, and CRISPLD2) were filtered to establish the signature and participated in building the nomogram. In comparison to the high-risk group, the overall survival (OS) was much longer in the low-risk group (P=0.005). The validation cohort demonstrated the acceptable predictive ability of the nomogram. The signature was enriched in biological features such as extracellular matrix organization, epithelial-mesenchymal transition and inflammatory response. Moreover, there were substantial differences in immune cell infiltration across the different risk groups (p<0.001), especially the high-risk group having more immune cells that are engaged in the antigen presentation process and associated functions. Finally, in the external cohort, NE-DNA levels were shown to be an independent factor affecting OS prognosis (p=0.006). Overall, this research identified a novel signature based on seven NETs-associated genes to predict prognosis and identify tumor microenvironment of GC. And high NE-DNA level may be a critical factor in the poor OS associated with NETs.

Prediction model of clinical prognosis and immunotherapy efficacy of gastric cancer based on level of expression of cuproptosis-related genes

BackgroundGastric cancer is one of the most common malignancies in the world and ranks fourth among cancer-related causes of death. Gastric adenocarcinoma is the most common pathological type of gastric cancer; usually, this tumor is associated with distant metastasis upon first diagnosis and has a poor prognosis. Cuproptosis is a novel mechanism of cell death induced by copper, and is closely related to tumor progression, prognosis and immune response. However, the role of cuproptosis-related genes (CRGs) in the tumor microenvironment (TME) of gastric cancer has yet to be elucidated. MethodsGastric adenocarcinoma data were downloaded from the Cancer Genome Atlas (TCGA) database. Through bioinformatics analysis, a risk scoring model was constructed from cuproptosis gene-related lncRNA. Then, we investigated the relationship between prognosis and the TIME of gastric cancer according to clinical characteristics and risk score. ResultsValidation of the model showed that the overall survival (OS) of the high-risk group was significantly lower than that of the low-risk group (P < 0.001) and that the risk score was an independent predictor of prognosis (P < 0.001). The new model was significantly correlated with the prognosis and TIME of patients with gastric cancer, including immune cell infiltration, tumor mutation burden (TMB) score, targeted drug sensitivity, and immune checkpoint gene expression. In addition, a prognostic nomogram was established based on the risk score (AC008915.2, AC011005.4, AC023511.1, AC139792.1, AL355312.2, LINC01094 and LINC02476). ConclusionOur analysis revealed that the prognostic model of cuproptosis-related genes could effectively predict the prognosis of patients with gastric cancer and comprehensively establish the relationship between cuproptosis genes and tumor immunity. This may provide a new strategy for the precise treatment of gastric cancer.

Gastric Cancer Derived Mesenchymal Stem Cells Promote the Migration of Gastric Cancer Cells Through miR-374a-5p.

Resident mesenchymal stem cells (MSCs) in the tumor microenvironment play an important role in tumor progression. Up to now, the mechanism of resident MSCs promoting gastric cancer cell migration remains unclear. We tested the migration ability of gastric cancer cells by transwell assays in this study. The inflammatory factors secreted by MSCs were detected by Luminex and ELISA. The activation of NF-κB signaling was detected by western blot. The exosomes derived from MSCs were isolated and identified by transmission electron microscope, nano-sight and western blot. The expression of miR-374a-5p was confirmed by qRT-PCR and its downstream target HAPLN1 by luciferase reporter assay. The expression of adhesion molecules of gastric cancer cells was detected by flow cytometry. MiR-374a-5p could regulate the expression of inflammatory factors by activating NF-κB signaling. The increase of MCP-1 and the decrease of IFN-γ promoted the migration of gastric cancer cells. The miR-374a-5p in MSCs could be encapsulated and delivered to gastric cancer cells by exosomes derived from MSCs. Exogenous miR-374a-5p up-regulated the expression of adhesion molecules in gastric cancer cells by targeting HAPLN1. And miR-374a-5p-enriched exosomes also promoted the migration of gastric cancer cells. MiR-374a-5p promoted gastric cancer metastasis, and resident MSCs in the gastric cancer microenvironment played a major role in the regulation of gastric cancer metastasis. The study will provide new ideas and potential targets for the prevention and treatment of gastric cancer metastasis.