CD33⁺/p-STAT1⁺ double-positive cell as a prognostic factor for stage IIIa gastric cancer

Multifaceted function of B cells in tumorigenesis

B lymphocytes (B cells) play a complex and paradoxical role in tumorigenesis. They can recognize tumor-associated antigens, present these antigens to T cells, and produce antibodies that directly target and eliminate tumor cells. This makes B cells a potentially powerful ally in combating cancer. However, B cells also exhibit immunosuppressive functions, secreting cytokines like IL-10 or generating tumor-promoting antibodies that dampen the anti-tumor immune response, and some tumor cells have even been shown to exploit B cells to promote their growth and metastasis. This dual nature of B cells presents both opportunities and challenges for tumor immunotherapy. In this review, we summarize the mechanisms underlying the multifaceted functions of B cells and their current applications in cancer immunotherapy. Furthermore, we also explore the key issues and future directions in this field, emphasizing the need for further research to fully harness the anti-tumor potential of B cells in the fight against cancer.

Prognostic role of tumor-infiltrating lymphocytes in gastric cancer: A systematic review and meta-analysis

BACKGROUND

To analyze the relationship between tumor-infiltrating lymphocytes (TILs) subtypes and infiltration locations and the prognosis of gastric cancer (GC) patients.

METHODS

Eligible articles were obtained through systematic retrieval and rigorous screening, collecting study information and extracting hazard ratio (HR), 95 % confidence interval (CI) for pooled analyses of disease-free survival (DFS) and overall survival (OS).

RESULTS

Higher CD4+ TILs were correlated with favorable OS (HR=0.79, 95 %CI: 0.66-0.94, P = 0.009), the similar results were observed in tumor center and in infiltration margin. Higher CD8+ TILs prolonged DFS (HR=0.69, 95 %CI: 0.51-0.95, P = 0.02) and OS (HR=0.96, 95 %CI: 0.94-0.99, P = 0.006); For OS, tumor center and infiltration margin groups showed positive results. Neither the overall analysis nor the subgroup analyses indicated that the level of FOXP3+ TILs was associated with prognosis (DFS: HR=0.89, 95 %CI: 0.66-1.19, P = 0.42; OS: HR=0.98, 95 %CI: 0.85-1.13, P = 0.75). Pooled results revealed that higher CD3+ TILs were correlated with favorable DFS (HR=0.69, 95 %CI: 0.56-0.84, P = 0.0003) but not OS (HR=1.00, 95 %CI: 0.99-1.01, P = 0.48).

CONCLUSIONS

High infiltrating CD3+, CD4+, CD8+ T cells prolong survival, and FOXP3+ subset is not related to prognosis in GC. For CD4+ and CD8+, positive correlations between the infiltration level and OS were present in tumor center and infiltration margin groups.

A novel semi-quantitative scoring method for CD8+ tumor-infiltrating lymphocytes based on infiltration sites in gastric cancer

No established method currently exists for evaluating tumor-infiltrating lymphocytes (TILs) in gastric cancer (GC), and their clinical significance based on infiltration site in GC remains unclear. In this study, we developed a method to evaluate TILs according to their infiltration site as a prognostic marker for GC. We retrospectively analyzed 103 patients with advanced GC who underwent curative resection. TILs located at the invasive margin (TILIM) and the center of tumors (TILCT) were scored semi-quantitatively using immunohistochemical staining of CD8+ T cells. The sum of the TILIM and TILCT scores was defined as the TILs score. Based on this score, patients were classified into low and high TILs groups. Quantitative TILs were also assessed to validate the semi-quantitative scoring method. Furthermore, we confirmed a tumor suppressive effect due to CD8+ T cells co-cultured in GC cell lines in vitro. In the univariate analysis, patients with low TILIM were significantly more likely to be female, younger, and have undifferentiated histological types and deeper tumor invasion compared to those with high TILIM. Similarly, patients with low TILCT had significantly more positive lymph node metastases than those with high TILCT. In the multivariate analysis, deeper tumor invasion and positive lymph node metastasis were identified as independent risk factors for patients with low TILIM and low TILCT, respectively. According to our semi-quantitative TILs scoring method, the low TILs group had significantly poorer prognoses compared to the high TILs group. This group had significantly larger tumor diameters, deeper tumor invasion, and more positive lymph node metastases. Additionally, deeper tumor invasion was an independent risk factor for the low TILs group. Quantitative TILs analysis revealed that the low TILs group had significantly lower TIL levels compared to the high TILs group. In vitro, CD8+ T cells induced apoptosis in GC cells in a concentration-dependent manner. Furthermore, these cells significantly suppressed the proliferative, migratory, and invasive capacities of GC cells. Our simple and versatile semi-quantitative scoring method for CD8+ TILs indicates that CD8+ TILs are sensitive prognostic markers. The low TILs group accurately reflects the low quantitative TIL levels and is associated with poor oncological prognosis.

The mechanisms on evasion of anti-tumor immune responses in gastric cancer

The immune system and the tumor have been at each other's throats for so long that the neoplasm has learned to avoid detection and avoid being attacked, which is called immune evasion. Malignant tumors, such as gastric cancer (GC), share the ability to evade the body's immune system as a defining feature. Immune evasion includes alterations to tumor-associated antigens (TAAs), antigen presentation mechanisms (APMs), and the tumor microenvironment (TME). While TAA and APM are simpler in nature, they both involve mutations or epigenetic regulation of genes. The TME is comprised of numerous cell types, cytokines, chemokines and extracellular matrix, any one of which might be altered to have an effect on the surrounding ecosystem. The NF-kB, MAPK, PI3K/AKT, JAK/STAT, Wnt/β-catenin, Notch, Hippo and TGF-β/Smad signaling pathways are all associated with gastric cancer tumor immune evasion. In this review, we will delineate the functions of these pathways in immune evasion.

Comprehensive Analysis of Stromal and Serum Markers in Gastric Cancer

A comprehensive analysis of the cell phenotype of the inflammatory infiltrate of the tumor stroma represents a promising area of molecular oncology. The study of not only soluble forms of various immunoregulatory molecules, but also their membrane-bound forms is also considered highly relevant. We performed a comprehensive analysis of tissue and circulating forms of the PD-1 and PD-L1 proteins, as well as macrophage and B-cell markers in the tumor stroma of gastric cancer, to assess their clinical and prognostic significance. The tumor and blood plasma samples from 63 gastric cancer patients were studied using ELISA and immunohistochemistry. Malignant gastric tumors were shown to be strongly infiltrated by B-cells, and their number was comparable to that of macrophages. For PU.1 expression, an association with tumor size was observed; i.e., larger tumors were characterized by fewer PU.1+ infiltrating cells (p = 0.005). No clinical significance was found for CD20 and CD163, but their numbers were higher at earlier stages of the disease and in the absence of metastases. It was also demonstrated that the PD-L1 content in tumor cells was not associated with the clinical and morphological characteristics of GC. At the same time, PD-L1 expression in tumor stromal cells was associated with the presence of distant metastases. The analysis of the prognostic significance of all the markers studied demonstrated that CD163 was statistically significantly associated with a poor prognosis for the disease (p = 0.019). In addition, PD-L1 expression in tumor cells tended to indicate a favorable prognosis (p = 0.122). The results obtained in this work indicate that the study of soluble and tissue markers of tumor stroma is promising in prognosticating the course of GC. The search for combinations of markers seems to be highly promising, with their comprehensive analysis capable of helping personalize advanced antitumor therapy.

Novel roles of LSECtin in gastric cancer cell adhesion, migration, invasion, and lymphatic metastasis

Liver and lymph node sinusoidal endothelial cell C-type lectin (LSECtin) plays an important regulatory role in a variety of diseases, including tumors. However, the underlying mechanism of LSECtin in gastric cancer (GC) remains largely unknown. In our research, LSECtin promoted the adhesion and invasion of GC cells, and was involved in lymphatic metastasis of GC cells. Mechanistically, LSECtin promoted the adhesion, proliferation and migration of GC cells by downregulating STAT1 expression. The circular RNA circFBXL4, which is regulated by LSECtin, sponges the microRNA miR-146a-5p to regulate STAT1 expression. The promotion of GC cell proliferation, migration and invasion mediated by LSECtin was largely inhibited by circFBXL4 overexpression or miR-146a-5p silencing. Moreover, in its role as a transcription factor, STAT1 modulated the expression of FN1 and CHD4. In conclusion, LSECtin might be involved in the lymphatic metastasis of GC by upregulating the expression of FN1 and CHD4 via the circFBXL4/miR-146a-5p/STAT1 axis, possibly indicating a newly discovered pathogenic mechanism.

Tumor immune microenvironment is influenced by frameshift mutations and tumor mutational burden in gastric cancer

PURPOSE

Immunoscore can effectively predict prognosis in patients with colon cancer; however, its clinical application is limited. We modified the Immunoscore and created a tumor immune microenvironment (TIM) classification system for gastric carcinoma. Unlike previous studies that used small sample sizes or focused on particular immune-cell subtypes, our simplified system enables pathologists to classify gastric carcinomas intuitively using H&E-stained sections.

METHODS

Samples from 326 patients with advanced gastric carcinoma were reviewed and analyzed by pathologists using simple determination and digital image analysis. Comprehensive results of cancer-panel sequencing, Epstein-Barr‒virus (EBV) status, and PD-L1, HER2, ATM, PTEN, MET, FGFR2, and EGFR immunohistochemistry were evaluated with respect to the TIM class.

RESULTS

The TIM was classified as "hot" (n = 22), "immunosuppressed" (n = 178), "excluded" (n = 83), or "cold" (n = 43). TIM category was significantly associated with numbers of frameshift mutations (P < 0.001) and high tumor mutational burden (P < 0.004), and predicted overall survival. It was also significantly associated with age, histological type, degree of fibrosis, PD-L1 expression, loss of ATM and PTEN expression (P < 0.001), sex, EBV positivity, and HER2 overexpression (P < 0.04). "Hot" tumors were frequent in PD-L1 expressing and EBV-positive samples, and in those with ATM and PTEN loss. "Excluded" tumors were frequent in HER2-positive cases, whereas "cold" tumors were more frequent in younger patients with poorly cohesive histology and high fibrosis levels.

CONCLUSIONS

TIM classification system for gastric carcinoma has prognostic significance and results in classes that are associated with molecular characteristics.

Re-Expression of Poly/Oligo-Sialylated Adhesion Molecules on the Surface of Tumor Cells Disrupts Their Interaction with Immune-Effector Cells and Contributes to Pathophysiological Immune Escape

Glycans linked to surface proteins are the most complex biological macromolecules that play an active role in various cellular mechanisms. This diversity is the basis of cell-cell interaction and communication, cell growth, cell migration, as well as co-stimulatory or inhibitory signaling. Our review describes the importance of neuraminic acid and its derivatives as recognition elements, which are located at the outermost positions of carbohydrate chains linked to specific glycoproteins or glycolipids. Tumor cells, especially from solid tumors, mask themselves by re-expression of hypersialylated neural cell adhesion molecule (NCAM), neuropilin-2 (NRP-2), or synaptic cell adhesion molecule 1 (SynCAM 1) in order to protect themselves against the cytotoxic attack of the also highly sialylated immune effector cells. More particularly, we focus on α-2,8-linked polysialic acid chains, which characterize carrier glycoproteins such as NCAM, NRP-2, or SynCam-1. This characteristic property correlates with an aggressive clinical phenotype and endows them with multiple roles in biological processes that underlie all steps of cancer progression, including regulation of cell-cell and/or cell-extracellular matrix interactions, as well as increased proliferation, migration, reduced apoptosis rate of tumor cells, angiogenesis, and metastasis. Specifically, re-expression of poly/oligo-sialylated adhesion molecules on the surface of tumor cells disrupts their interaction with immune-effector cells and contributes to pathophysiological immune escape. Further, sialylated glycoproteins induce immunoregulatory cytokines and growth factors through interactions with sialic acid-binding immunoglobulin-like lectins. We describe the processes, which modulate the interaction between sialylated carrier glycoproteins and their ligands, and illustrate that sialic acids could be targets of novel therapeutic strategies for treatment of cancer and immune diseases.

Identification of a Five-Gene Prognostic Signature Related to B Cells Infiltration in Pancreatic Adenocarcinoma

Background

Pancreatic adenocarcinoma (PAAD) is an extremely malignant cancer. Immunotherapy is a promising avenue to increase the survival time of patients with PAAD.

Methods

RNA sequencing and clinical data for PAAD were downloaded from the TCGA database. The ssGSEA method and weighted gene co-expression network analysis were used to calculate the relative abundance of tumor-infiltrating immune cells and identify the related modules. Least absolute shrinkage and selection operator (LASSO) and Cox regression analyses were used to construct a prognostic model. MCPcounter and EPIC were also used to assess immune cell components using gene expression profiles.

Results

The B cells closely related module was identified, and five genes, including ARID5A, CLEC2B, MICAL1, MZB1, and RAPGEF1, were ultimately selected to establish a prognostic signature to calculate the risk scores of PAAD patients. Kaplan–Meier curves showed worse survival in the high-risk patients (p < 0.05), and the area under the receiver operating characteristic (ROC) curves of risk score for 1-year and 3-year survival were 0.78 and 0.80, respectively, based on the training set. Similar results were verified using the validated and combined sets. Interestingly, the low-risk group presented significantly elevated immune and stromal scores, proportion of B cells, and associations between these five genes and B cells were identified using multiple methods including ssGSEA, MCPcounter, and EPIC.

Conclusion

This is the first attempt to study a B cells-related prognostic signature, which is instrumental in the exploration of novel prognostic biomarkers in PAAD.

Prediction of prognosis of patients with lung cancer in combination with the immune score

PURPOSE

The host's immune response to malignant tumor is fundamental to tumorigenesis and tumor development. The immune score is currently used to assess prognosis and to guide immunotherapy; however, its association with lung cancer prognosis is not clear.

METHODS

Clinical features and immune score data of lung cancer patients from The Cancer Genome Atlas were obtained to build a clinical prognosis nomogram. The model's accuracy was verified by calibration curves.

RESULTS

In total, 1005 patients with lung cancer were included. Patients were divided into three groups according to low, medium, and high immune scores. Compared with patients in the low immune score group, the disease-free survival (DFS) of patients in medium and high immune score groups was significantly longer; the hazard ratio (HR) and 95% confidence interval (95% CI) were 0.77 [0.60-0.99] and 0.74 [0.60-0.91], respectively. The overall survival (OS) of patients in the medium and high immune score groups was significantly longer than in the low immune score group; the HR and 95% CI were 0.74 [0.57-0.96] and 0.69 [0.55-0.88], respectively. A clinical prediction model was established to predict the survival prognosis. As verified by calibration curves, the model showed good predictive ability, especially for predicting 3-/5-year DFS and OS.

CONCLUSION

Patients with lung cancer with medium and high immune scores had longer DFS and OS than those in low immune score group. Patient prognosis can be effectively predicted by the clinical prediction model combining clinical features and immune score and was consistent with actual clinical outcomes.

High CD8/CD33 ratio in peritoneal metastatic lesions is associated with favorable prognosis in gastric cancer

Background

Tumor‐infiltrating lymphocytes (TILs) and other immune cells have been reported as a prognostic factor in several tumors, including gastric cancer, and they play an important role in antitumor effect at the primary site. There were few reports on the immune status in peritoneal metastatic lesions for gastric cancer.

Aims

The aims of this study were to assess the prognostic significance of TILs (CD4, CD8, CD19, regulatory T cells [Tregs]), and myeloid‐derived suppressor cells (MDSCs) in peritoneal metastatic lesions.

Methods

We retrospectively investigated 60 patients for gastric cancer with peritoneal metastasis who were treated between 2009 and 2016 in our institute. Immunohistochemistry for CD4, CD8, CD19, FOXP3, and CD33 was performed in the peritoneal metastatic lesions. The absolute numbers of immune cells and ratios were evaluated, and the relationship between immune‐related marker and overall survival (OS) was investigated.

Results

A high infiltration of CD8⁺ lymphocytes or high CD8/CD33 ratio was a better prognosis for OS in univariate analysis using all immunologic variables (P = .012, P = .001). In multivariate analysis for clinical and immunologic variables, high CD8/CD33 ratio was identified as an independent prognostic factor for OS (Hazard ratio: 0.291, 95% confidence interval: 0.126‐0.670, P = .004).

Conclusion

High CD8/CD33 ratio and high infiltration of CD8⁺ lymphocytes in peritoneal metastatic lesions were favorable prognoses for gastric cancer patients with peritoneal metastasis. It is necessary to modify the immune microenvironment result to increase the level of CD8⁺ lymphocytes in the peritoneal metastatic lesions.

The role of myeloid-derived suppressor cells in gastrointestinal cancer

Gastrointestinal (GI) cancer encompasses a range of malignancies that originate in the digestive system, which together represent the most common form of cancer diagnosed worldwide. However, despite numerous advances in both diagnostics and treatment, the incidence and mortality rate of GI cancer are on the rise. Myeloid-derived suppressor cells (MDSCs) are a heterogeneous population of immature myeloid cells that increase in number under certain pathological conditions, such as infection and inflammation, and this expansion is of particular relevance to cancer. MDSCs are heavily involved in the regulation of the immune system and act to dampen its response to tumors, favoring the escape of tumor cells from immunosurveillance and increasing both metastasis and recurrence. Several recent studies have supported the use of MDSCs as a prognostic and predictive biomarker in patients with cancer, and potentially as a novel treatment target. In the present review, the mechanisms underlying the immunosuppressive functions of MDSCs are described, and recent researches concerning the involvement of MDSCs in the progression, prognosis, and therapies of GI cancer are reviewed. The aim of this work was to present the development of novel treatments targeting MDSCs in GI cancer in the hope of improving outcomes for patients with this condition.

Digital image analysis in pathologist-selected regions of interest predicts survival more accurately than whole-slide analysis: a direct comparison study in 153 gastric carcinomas

Automatic quantification of biomarkers such as tumor‐infiltrating lymphocytes and PD‐L1 is one of the most studied topics in digital pathology image analysis (DIA). However, direct comparison between the DIA of a whole‐slide image (WSI) and that of regions of interest (ROIs) chosen by pathologists has not been performed. In this study, we aimed to compare the prognostic value of tumor microenvironment markers CD8 and PD‐L1, measured by DIA of WSIs and ROIs. We selected 153 primary gastric cancer tissues and stained them with CD8 and PD‐L1. All IHC slides were scanned at ×200 magnification and ratios of CD8 and PD‐L1 were measured in WSIs and ROIs from the invasive front, within the tumor, and the mucosa. Patients with high CD8 and PD‐L1 ratios showed more favorable outcomes compared to those with low ratios. Pathologist‐aided DIA predicted the survival of patients more accurately than WSI analysis (CD8, p = 0.025 versus p = 0.068; PD‐L1, p = 0.008 versus p = 0.2). Although a high density of CD8+ T cells at the invasive front correlated best with patient survival, CD8 ratio in the mucosa could also predict patient outcome. In conclusion, CD8 and PD‐L1 ratios measured by pathologist‐aided DIA predicted survival more accurately than WSI analyses and ROIs at the invasive front correlated best with patient outcome.

Extravasated platelet aggregation contributes to tumor progression via the accumulation of myeloid-derived suppressor cells in gastric cancer with peritoneal metastasis

Extravasated platelet aggregation (EPA) serves an important role in the cancer microenvironment during cancer progression, and has been demonstrated to interact with tumor cells in several types of cancer. EPA induces epithelial-mesenchymal transition (EMT) via transforming growth factor-β, and also recruits immunosuppressive cells, including regulatory T (Treg) cells and myeloid-derived suppressor cells (MDSCs). However, the role of EPA in gastric cancer with peritoneal metastasis remains unknown. The present study analyzed the association between EPA and prognosis in patients with gastric cancer with peritoneal metastasis. The present study evaluated 62 patients diagnosed with advanced gastric cancer with peritoneal metastasis between 2001 and 2016. EPA, EMT, Treg cells and MDSCs in peritoneal metastatic lesions were detected by immunohistochemical evaluation of CD42b, SNAIL, FOXP3 and CD33, respectively. CD42b expression was observed in 56.5% (35/62) of peritoneal metastatic lesions. CD42b expression in peritoneal metastatic lesions was associated with poor overall survival compared with lower frequencies (hazard ratio, 2.03; 95% confidence interval, 1.12-3.69; P=0.018). SNAIL, FOXP3 and CD33 expression were not associated with overall survival, but CD33 expression was markedly higher in CD42b-positive patients (P=0.022). These results indicated that EPA affects immunosuppression by recruiting MDSCs in the tumor microenvironment via the secretion of soluble factors, resulting in tumor progression. EPA may be a novel therapeutic target for gastric cancer with peritoneal metastasis.

B cells in esophago-gastric adenocarcinoma are highly differentiated, organize in tertiary lymphoid structures and produce tumor-specific antibodies

Tumor-infiltrating lymphocytes (TILs) are correlated to prognosis of several kinds of cancer. Most studies focused on T cells, while the role of tumor-associated B cells (TABs) has only recently gained more attention. TABs contain subpopulations with distinct functions, potentially promoting or inhibiting immune responses. This study provides a detailed analysis of TABs in gastro-esophageal adenocarcinoma (EAC). Flow cytometric analyses of single cell suspensions of tumor samples, mucosa, lymph nodes and peripheral blood mononuclear cells (PBMC) of EAC patients and healthy controls revealed a distinct B cell compartment in cancer patients. B cells were increased in tumor samples and subset-analyses of TILs showed increased proportions of differentiated and activated B cells and an enrichment for follicular T helper cells. Confocal microscopy demonstrated that TABs were mainly organized in tertiary lymphoid structures (TLS), which resemble lymphoid follicles in secondary lymphoid organs. A panel of 34 tumor-associated antigens (TAAs) expressed in EAC was identified based on public databases and TCGA data to analyze tumor-specific B cell responses using a LUMINEXTM bead assay and flow cytometry. Structural analyses of TLS and the detection of tumor-specific antibodies against one or more TAAs in 48.1% of analyzed serum samples underline presence of anti-tumor B cell responses in EAC. Interestingly, B cells were decreased in tumors with expression of Programmed Death Ligand 1 or impaired HLA-I expression. These data demonstrate that anti-tumor B cell responses are an additional and underestimated aspect of EAC. Our results are of immediate translational relevance to emerging immunotherapies.

Prognostic role of tumor-infiltrating lymphocytes in gastric cancer: A systematic review and meta-analysis

BACKGROUND

The potential prognostic value of tumor-infiltrating lymphocytes (TILs) in gastric cancer remains controversial. This meta-analysis examines the association between TILs and survival outcomes in gastric cancer.

METHODS

Twenty-two eligible studies were identified using the PubMed and Google Scholar databases. The combined sample size of the 22 studies was 2941, and the median sample size of the individual studies was 122 patients (52-220). The main clinical outcomes examined were overall cancer survival (OCS) and overall cancer relapse-free survival (OCRFS).

RESULTS

Tumor tissue CD3(+) TILs, indicative of pan-T-cell expression, had a positive effect on survival with a hazard ratio (HR) of 0.64 (95% confidence interval [CI] 0.52-0.78) for OCS, as did the non-FOXP3(+) T-cell subgroup with an HR of 0.66 (95% CI 0.57-0.75), particularly in CD8(+) lymphocytes (HR = 0.63, 95% CI 0.48-0.83). On the contrary, high FOXP3(+) T-cell expression was correlated with reduced OCS, with an HR of 1.75 (95% CI 1.26-2.42). Analysis of the seven studies evaluating OCRFS revealed improved OCRFS with infiltration of non-FOXP3(+) TILs with an HR of 0.59 (95% CI 0.42-0.81) but not FOXP3(+) T lymphocytes with an HR of 1.82 (95% CI 1.30-2.53).

CONCLUSION

The results from this meta-analysis suggest that high expression of TILs, mainly by CD8 lymphocytes, may be a potential prognostic biomarker in patients with gastric cancer.

Prognostic role of pretreatment circulating MDSCs in patients with solid malignancies: A meta-analysis of 40 studies

Myeloid-derived suppressor cells (MDSCs) have been shown to contribute to tumor progression, mainly through immune suppression. Inverse correlations have been observed between MDSC levels and patient survival for various malignancies. The purpose of this meta-analysis was to evaluate the prognostic value of pretreatment circulating MDSCs. We searched MEDLINE and EMBASE from their inceptions to September 2017 to identify relevant articles. Using a fixed or random effects model, pooled hazard ratios (HRs) were estimated for overall survival (OS) and combined disease-free survival, progression-free survival, and recurrence-free survival (DFS/PFS/RFS). A total of 40 studies comprising 2721 were included. For solid tumors, high levels of pretreatment circulating MDSCs were significantly associated with worse OS (HR = 1.796, 95% CI = 1.587-2.032) and DFS/PFS/RFS (HR = 2.459, 95% CI = 2.018-2.997). Breast cancer showed the largest association between high MDSC levels and worse OS (pooled HR = 3.053). Elevated MDSCs were also associated with worse OS for mixed-stage tumors (pooled HR = 1.659) and advanced-stage tumors (pooled HR = 2.337). Furthermore, both monocytic-MDSCs (M-MDSCs) and granulocytic or polymorphonuclear (PMN-MDSCs) showed negative associations with survival outcomes. Overall, high levels of pretreatment circulating MDSCs negatively influenced survival in most cancers. Pretreatment circulating MDSCs should be taken into account to further improve prognostic evaluation and develop novel therapeutic strategies.

The Microenvironment in Epstein-Barr Virus-Associated Malignancies

The Epstein–Barr virus (EBV) can cause a wide variety of cancers upon infection of different cell types and induces a highly variable composition of the tumor microenvironment (TME). This TME consists of both innate and adaptive immune cells and is not merely an aspecific reaction to the tumor cells. In fact, latent EBV-infected tumor cells utilize several specific mechanisms to form and shape the TME to their own benefit. These mechanisms have been studied largely in the context of EBV+ Hodgkin lymphoma, undifferentiated nasopharyngeal carcinoma, and EBV+ gastric cancer. This review describes the composition, immune escape mechanisms, and tumor cell promoting properties of the TME in these three malignancies. Mechanisms of susceptibility which regularly involve genes related to immune system function are also discussed, as only a small proportion of EBV-infected individuals develops an EBV-associated malignancy.

GLI1-mediated regulation of side population is responsible for drug resistance in gastric cancer

Gastric cancer is the third leading cause of cancer-related mortality worldwide. Chemotherapy is frequently used for gastric cancer treatment. Most patients with advanced gastric cancer eventually succumb to the disease despite some patients responded initially to chemotherapy. Thus, identifying molecular mechanisms responsible for cancer relapse following chemotherapy will help design new ways to treat gastric cancer. In this study, we revealed that the residual cancer cells following treatment with chemotherapeutic reagent cisplatin have elevated expression of hedgehog target genes GLI1, GLI2 and PTCH1, suggestive of hedgehog signaling activation. We showed that GLI1 knockdown sensitized gastric cancer cells to CDDP whereas ectopic GLI1 expression decreased the sensitivity. Further analyses indicate elevated GLI1 expression is associated with an increase in tumor sphere formation, side population and cell surface markers for putative cancer stem cells. We have evidence to support that GLI1 is critical for maintenance of putative cancer stem cells through direct regulation of ABCG2. In fact, GLI1 protein was shown to be associated with the promoter fragment of ABCG2 through a Gli-binding consensus site in gastric cancer cells. Disruption of ABCG2 function, through ectopic expression of an ABCG2 dominant negative construct or a specific ABCG2 inhibitor, increased drug sensitivity of cancer cells both in culture and in mice. The relevance of our studies to gastric cancer patient care is reflected by our discovery that high ABCG2 expression was associated with poor survival in the gastric cancer patients who underwent chemotherapy. Taken together, we have identified a molecular mechanism by which gastric cancer cells gain chemotherapy resistance.

The role of GLI2-ABCG2 signaling axis for 5Fu resistance in gastric cancer

Gastric cancer is a leading cause of cancer-related mortality worldwide, and options to treat gastric cancer are limited. Fluorouracil (5Fu)-based chemotherapy is frequently used as a neoadjuvant or an adjuvant agent for gastric cancer therapy. Most patients with advanced gastric cancer eventually succumb to the disease despite the fact that some patients respond initially to chemotherapy. Thus, identifying molecular mechanisms responsible for chemotherapy resistance will help design novel strategies to treat gastric cancer. In this study, we discovered that residual cancer cells following 5Fu treatment have elevated expression of hedgehog (Hg) target genes GLI1 and GLI2, suggestive of Hh signaling activation. Hh signaling, a pathway essential for embryonic development, is an important regulator for putative cancer stem cells/residual cancer cells. We found that high GLI1/GLI2 expression is associated with some features of putative cancer stem cells, such as increased side population. We demonstrated that GLI2 knockdown sensitized gastric cancer cells to 5Fu treatment, decreased ABCG2 expression, and reduced side population. Elevated GLI2 expression is also associated with an increase in tumor sphere size, another marker for putative cancer stem cells. We believe that GLI2 regulates putative cancer stem cells through direct regulation of ABCG2. ABCG2 can rescue the GLI2 shRNA effects in 5Fu response, tumor sphere formation and side population changes, suggesting that ABCG2 is an important mediator for GLI2-associated 5Fu resistance. The relevance of our studies to gastric cancer patient care is reflected by our discovery that high GLI1/GLI2/ABCG2 expression is associated with a high incidence of cancer relapse in two cohorts of gastric cancer patients who underwent chemotherapy (containing 5Fu). Taken together, we have identified a molecular mechanism by which gastric cancer cells gain 5Fu resistance.

Clinical significance of tumor-infiltrating lymphocytes for gastric cancer in the era of immunology

Immunotherapy has begun to revolutionize cancer treatment, by introducing therapies that target the host immune system instead of the tumor, therapies that possess unique adverse event profiles, and therapies that may cure certain types of cancer. The immune microenvironment of tumors is emerging as the most important means of understanding the relationship between a patient' immune system and their cancer, informing prognosis, and guiding immunotherapy, such as an antibody blockade of immune checkpoints. For some solid tumors, simple quantitation of lymphocyte infiltration would seem to have prognostic significance, suggesting that lymphocyte infiltration is not passive but may actively promote or inhibit tumor growth. For gastric cancers, several studies have provided strong evidence that immune cells contribute to determining prognosis. However, the exact role of immune cells in gastric cancer remains unclear. Therefore, this review focuses on the clinical significance of immune cells, especially tumor-infiltrating lymphocytes, in gastric cancer.

Prognostic role of tumor-infiltrating lymphocytes in gastric cancer: a meta-analysis

Background

In patients with gastric cancer, the prognostic value of tumor-infiltrating lymphocytes (TILs) is still controversial. A meta-analysis was performed to evaluate the prognostic value of TILs in gastric cancer.

Materials and methods

We identify studies from PubMed, Embase and the Cochrane Library to assess the prognostic effect of TILs in patients with gastric cancer. Fixed-effects models or random-effects models were used estimate the pooled hazard ratios (HRs) for overall survival (OS) and disease-free survival (DFS), which depend on the heterogeneity.

Results

A total of 31 observational studies including 4,185 patients were enrolled. For TILs subsets, the amount of CD8⁺, FOXP3⁺, CD3⁺, CD57⁺, CD20⁺, CD45RO⁺, Granzyme B⁺ and T-bet⁺ lymphocytes was significantly associated with improved survival (P < 0.05); moreover, the amount of CD3+ TILs in intra-tumoral compartment (IT) was the most significant prognostic marker (pooled HR = 0.52; 95% CI = 0.43–0.63; P < 0.001). However, CD4⁺ TILs was not statistically associated with patients’ survival. FOXP3+ TILs showed bidirectional prognostic roles which had positive effect in IT (pooled HR = 1.57; 95% CI = 1.04–2.37; P = 0.033) and negative effect in extra-tumoral compartment (ET) (pooled HR = 0.76; 95% CI = 0.60–0.96; P = 0.022).

Conclusions

This meta-analysis suggests that some TIL subsets could serve as prognostic biomarkers in gastric cancer. High-quality randomized controlled trials are needed to decide if these TILs could serve as targets for immunotherapy in gastric cancer.

Myeloid-derived suppressor cells in gastrointestinal cancers: A systematic review

BACKGROUND AND AIM

Gastrointestinal (GI) cancers are a heterogeneous group of cancers originating from the digestive system. Considering key roles of myeloid-derived suppressor cells (MDSCs) in the immunosuppression network, levels of MDSCs in patients with cancer are assumed to be of prognostic and predictive value. In this systematic review, we aimed to evaluate the clinical relevancy of MDSCs and their relationship with clinical features and prognosis of GI malignancies in patients with GI cancers.

METHODS

We searched Medline, Scopus, DART, OpenGrey, and ProQuest without applying any language filter up to 1 August 2015. Two of the authors independently reviewed search results for irrelevant and duplicate studies and extracted data from studies. We used tabulation to synthesize the findings of the studies and transformed data into a common rubric and calculated a weighted treatment effect across studies using Review Manager.

RESULTS

We found 1238 references in five databases, and after exclusion of irrelevant and duplicate studies, 17 studies with a total number of 1115 patients with GI cancers were included. A meta-analysis of three studies showed associations of high MDSC levels with higher mortality during follow-up periods (hazard ratio = 3.35; 95% confidence interval = 1.46-7.68, P = 0.0004). A meta-analysis of four studies showed that patients with higher levels of MDSC had higher odds of having an advanced cancer (odds ratio = 2.64; 95% confidence interval = 1.53-4.53; P = 0.0004). There were also significant associations between MDSC levels and relapse, tumor progression, lymph node involvement, and metastasis.

CONCLUSION

In conclusion, results of this systematic review based on the available literature suggest that MDSC levels are of clinical relevancy and prognostic and predictive value.

Prognostic potential of an immune score based on the density of CD8+ T cells, CD20+ B cells, and CD33+/p-STAT1+ double-positive cells and HMGB1 expression within cancer nests in stage IIIA gastric cancer patients

OBJECTIVE

There is heterogeneity in the prognosis of gastric cancers staged according to the tumornodes- metastasis (TNM) system. This study evaluated the prognostic potential of an immune score system to supplement the TNM staging system.

METHODS

An immunohistochemical analysis was conducted to assess the density of T cells, B cells, and myeloid-derived suppressor cells (MDSCs) in cancer tissues from 100 stage IIIA gastric cancer patients; the expression of the high-mobility group protein B1 (HMGB1) was also evaluated in cancer cells. The relationship between the overall survival (OS), disease-free survival (DFS), and immunological parameters was analyzed.

RESULTS

An immune score system was compiled based on the prognostic role of the density of T cells, B cells, MDSCs, and the expression of HMGB1 in cancer tissues. The median 5-year survival of this group of patient was 32%. However, the 5-year survival rates of 80.0%, 51.7%, 0%, 5.8%, and 0% varied among the patients with an immune score of 4 to those with an immune score of 0 based on the immune score system, respectively. Similarly, differences in DFS rates were observed among the immune score subgroups.

CONCLUSIONS

An immune score system could effectively identify the prognostic heterogeneity within stage IIIA gastric cancer patients, implying that this immune score system may potentially supplement the TNM staging system, and help in identifying a more homogeneous group of patients who on the basis of prognosis can undergo adjuvant therapy.

Ectopic expression of B and T lymphocyte attenuator in gastric cancer: a potential independent prognostic factor in patients with gastric cancer

It has been confirmed that B and T lymphocyte attenuator (BTLA; also known as CD272) is a novel co--inhibitory molecule that exhibits a critical role in restraining cell-mediated antitumor immunity. The present study aimed to investigate the expression and prognostic significance of BTLA in gastric adenocarcinoma. Immunohistochemical (IHC) staining was performed to investigate BTLA expression in gastric cancer tissues and normal mucosal tissues. In total, 123 pathologically confirmed specimens were obtained from stage IIIa gastric cancers. A correlation test, Kaplan-Meier curves, and a Cox proportional hazards regression model were used to analyze the data. No BTLA staining in the normal tissues was found, while BTLA-stained gastric carcinoma cells were detected in 75.6% (93/123) of the gastric cancer specimens. High expression levels of BTLA were detected in 31.7% (39/123) of the specimens, while low expression levels were detected in 68.3% (84/123) of the specimens. High BTLA expression levels were associated with shorter survival time, as confirmed by univariate and multivariate analyses. These findings provide a basis for the concept that high BTLA expression levels in gastric cancer, identified by IHC, are an independent biomarker for the poor prognosis of patients with gastric cancer.

Manipulation of tumour-infiltrating B cells and tertiary lymphoid structures: a novel anti-cancer treatment avenue?

Combining different standard therapies with immunotherapy for the treatment of solid tumours has proven to yield a greater clinical benefit than when each is applied separately; however, the percentage of complete responses is still far from optimal, and there is an urgent need for improved treatment modalities. The latest literature data suggest that tertiary lymphoid structures (TLS), previously shown to correlate with the severity of autoimmune diseases or transplant rejection, are also formed in tumours, have a significant beneficial effect on survival and might reflect the generation of an effective immune response in close proximity to the tumour. Thus, the facilitation of TLS formation in tumour stroma could provide novel means to improve the efficiency of immunotherapy and other standard therapies. However, little is known about the mechanisms regulating the formation of tumour-associated TLS. Studies of chronic inflammatory diseases and transplant rejection have demonstrated that TLS formation and/or function requires the presence of B cells. Additionally, the infiltration of B cells into the tumour stroma has been demonstrated to be a significant prognostic factor for improved survival in different human tumours. This suggests that B cells could play a beneficial role in anti-tumour immune response not only in the context of antibody production, antigen presentation and Th1-promoting cytokine production, but also TLS formation. This review focuses on the latest discoveries in tumour-infiltrating B cell functions, their role in TLS formation and relevance in human tumour control, revealing novel opportunities to improve cancer therapies.

Inflammation-related factors predicting prognosis of gastric cancer

Gastric cancer (GC), which is mainly induced by Helicobacter pylori (H. pylori) infection, is one of the leading causes of cancer-related death in the developing world. Active inflammation initiated by H. pylori infection and maintained by inherent immune disorders promotes carcinogenesis and postoperative recurrence. However, the presence with H. pylori in tumors has been linked to a better prognosis, possibly due to the induction of antitumor immunity. Tumor infiltrations of tumor-associated macrophages, myeloid-derived suppressor cells, neutrophils, Foxp3⁺ regulatory T cells are correlated with poor prognosis. Tumor infiltrating CD8⁺ cytotoxic T lymphocytes, dendritic cells, and CD45RO T cells are generally associated with good prognosis of GC, although some subsets of these immune cells have inverse prognosis prediction values. High ratios of Foxp3⁺/CD4⁺ and Foxp3⁺/CD8⁺ in tumors are associated with a poor prognosis; whereas high Th1/Th2 ratio in tumors predicts a good prognosis. High levels of interleukin (IL)-6, IL-10, IL-32, and chemokine C-C motif ligands (CCL)7 and CCL21 in circulation, high expression of CXC chemokine receptor 4, chemokine C-C motif receptor (CCR)3, CCR4, CCR5, CCR7, hypoxia-inducible factor-1α, signal transducer activator of transcription-3, cyclooxygenase-2, and orphan nuclear receptor 4A2 in tumors are associated with an unfavorable prognosis. Increased serum levels of matrix metalloproteinases (MMP)-3, MMP-7, and MMP-11 and increased levels of MMP-9, MMP-12, and MMP-21 in tumors are consistently associated with poor survival of GC. Further emphasis should be put on the integration of these biomarkers and validation in large cohorts for personalized prediction of GC postoperative prognosis.