Gastric Cancer Cell Tissues Research Articles

Utilizing machine learning to integrate single-cell and bulk RNA sequencing data for constructing and validating a novel cell adhesion molecules related prognostic model in gastric cancer

BackgroundCell adhesion molecules (CAMs) play a vital role in cell-cell interactions, immune response modulation, and tumor cell migration. However, the unique role of CAMs in gastric cancer (GC) remains largely unexplored. MethodsThis study characterized the genetic alterations and mRNA expression of CAMs. The role of CD34, a representative molecule, was validated in 375 GC tissues. The activity of the CAM pathway was further tested using single-cell and bulk characterization. Next, data from 839 patients with GC from three cohorts was analyzed using univariate Cox and random survival forest methods to develop and validate a CAM-related prognostic model. ResultsMost CAM-related genes exhibited multi-omics alterations and were associated with clinical outcomes. There was a strong correlation between increased CD34 expression and advanced clinical staging (P = 0.026), extensive vascular infiltration (P = 0.003), and unfavorable prognosis (Log-rank P = 0.022). CD34 expression was also found to be associated with postoperative chemotherapy and tumor immunotherapy response. Furthermore, the CAM pathway was significantly activated and mediated poor prognosis. Additionally, eight prognostic signature genes (PSGs) were identified in the training cohort. There was a substantial upregulation of the expression of immune checkpoints and a pronounced infiltration of immune cells in GC tissues with high PSG score, which is consistent with the prediction of increased sensitivity to immunotherapy. Moreover, 9 compounds from the CTRPv2 database and 13 from the Profiling Relative Inhibition Simultaneously in Mixture (PRISM) database were identified as potential therapeutic drugs for patients with GC with high PSG score. ConclusionThorough understanding of CAM pathways regulation and the innovative PSG score model hold significant implications for medical diagnosis, potentially enhancing personalized treatment strategies and improving patient outcomes in GC management.

Construction of a Cuprotosis-Related Gene-Based Model to Improve the Prognostic Evaluation of Patients with Gastric Cancer.

Background Gastric cancer (GC) is one of the most serious gastrointestinal malignancies with bad prognosis. The association between GC and cuprotosis-related genes has not been reported. Methods The clinical and RNA expression of patients with GC were downloaded from TCGA database. The CIBERSORT package was used to quantify the abundance of specific cell types. Using the Cox regression analysis, we conducted a prognostic nomogram model based on cuprotosis-related differential genes in GC. We evaluated the prognostic power of this model using the Kaplan-Meier (K-M) survival curve analysis, decision curve analysis (DCA), and receiver operating characteristic (ROC) curve analysis. Results The plasma cells, monocytes, and mast cells in GC tissue were significantly less than those in adjacent tissue (p < 0.05), while T cell CD4 memory activated macrophage M0, macrophage M1, and macrophages in GC tissue. The number of M2 was significantly more than that in the adjacent tissue (p < 0.05). Additionally, GC patients in the test group, the training group, and all the sample groups had shorter survival time with the increase of the risk factor (p < 0.05). The nomogram of GC based on cuprotosis prognosis-related genes was conducted. The AUC of the nomogram to predict 1-, 3-, and 5-year survival rate was 0.618, 0.618, and 0.625, respectively. Conclusion A novel cuprotosis-related gene signature impacts on the prognosis of GC. Our research provides new insights and potential targets for studying the link between GC and cuprotosis point, thereby providing new insights into understanding the molecular mechanism of GC.

Infiltration and Significance of CD103+CD8+ T Cells in Gastrointestinal Adenocarcinoma.

Immunohistochemical staining is a common technique to study tissue morphology and in situ protein expression. With the rise of immunotherapy, more and more markers in the tumor microenvironment have been discovered. In this paper, the multiplex immunofluorescence staining method was used to stain paraffin sections of 35 cases of gastric adenocarcinoma tissue and 35 cases of colorectal adenocarcinoma tissue and its adjacent tissue. The infiltration of CD8+ T cells and CD103+CD8+ T cells in the slices was detected by using the slice scanner to form the map and CaseViewer2.0 software analysis. The experimental results in this paper showed that compared with adjacent tissues, the infiltration degree of CD8+ T cells in gastric adenocarcinoma tissue was significantly lower (Z = 2.244, P = 0.025, P < 0.05), and the infiltration degree of cells was significantly lower (Z = 2.785, P = 0.005, P < 0.05). In gastric adenocarcinoma tissue, the infiltration of CD8+ T cells was correlated with the tumor diameter of gastric adenocarcinoma (P = 0.002). There was a statistically significant difference. The degree of CD103+CD8+ T cell infiltration was related to the survival of patients with gastric adenocarcinoma (P = 0.002) and the degree of tumor differentiation (P = 0.004). The infiltration of CD103+CD8+ T cells in gastric cancer tissue and colorectal cancer tissue is related to the survival of patients. CD103+CD8+ T cells are thought to play a role in the prognosis of gastric adenocarcinoma and colorectal adenocarcinoma. Experiments have shown that the more the CD103+CD8+ T cells, the better the prognosis of gastric adenocarcinoma and colorectal adenocarcinoma, so the prognosis of gastric adenocarcinoma and colorectal adenocarcinoma can be improved by increasing CD103+CD8+ T cells.

Intratumoral PD-1+CD8+ T cells associate poor clinical outcomes and adjuvant chemotherapeutic benefit in gastric cancer

BackgroundAlthough PD-1 has been reported to be a marker of T-cell exhaustion in several malignancies, the biological role of PD-1+CD8+ T cells in gastric cancer (GC) remains unclear. Herein, we aimed to investigate the role of PD-1+CD8+ T cells in the tumour microenvironment and its clinical significance in GC.DesignsThis study included 441 tumour microarray specimens and 60 Flow cytometry specimens of GC patients from Zhongshan Hospital, and 250 GC patients from the Asian Cancer Research Group.ResultsHere, we demonstrated that PD-1+CD8+ T cells functioned as an independent adverse prognosticator in GC. In addition, an abundance of intratumoral PD-1+CD8+ T cells indicated worse chemotherapeutic responsiveness to fluorouracil in Stage III GC patients. Mechanistically, PD-1+CD8+ T cell high infiltration indicated an exhausted phenotype of global CD8+ T cells in GC tissues, which was characterised by elevated immune checkpoint expression including CTLA-4 and TIM-3, whereas decreased expression of perforin. Furthermore, PD-1+CD8+ T cell high-infiltration patients with Stage III GC held elevated activity of several therapeutic signal pathways.ConclusionsOur study highlighted that PD-1+CD8+ T cell abundance predicts inferior prognosis in GC, and may serve as a novel predictive biomarker to guide therapeutic option.

Cytolytic activity score as a biomarker for antitumor immunity and clinical outcome in patients with gastric cancer.

BackgroundA simple measure of immune cytolytic activity (CYT) base on mRNA expression levels of two genes, GZMA and PRF1, was recently reported. Here, we aimed to evaluate the CYT score's potential as a measure of antitumor immunity and predictor of clinical outcome in gastric cancer (GC) patients.Materials and MethodsWe evaluated the correlations between tumor‐infiltrating immune cells and the CYT score in 238 GC samples from The Cancer Genome Atlas (TCGA). Next, we investigated CYT score associations with molecular subtypes, somatic mutation load, and immune checkpoint molecules in GC samples from TCGA and Asian Cancer Research Group (ACRG). Moreover, we evaluated the clinical significance of the CYT score calculated by reverse transcription (RT)‐quantitative PCR (qPCR) data in 123 GC samples and the association of the CYT score with the response to anti‐PD‐1 therapy in 7 GC samples from Kyushu University Hospital.ResultsThe CYT score positively correlated with the proportions of tumor‐infiltrating CD8+ T cells and macrophages and negatively correlated with the proportion of regulatory T cells in GC tissues. A high CYT score was associated with common immune checkpoint molecules, a high mutation, the Epstein–Barr virus subtype, and the microsatellite instability subtype in GC. Moreover, a low CYT score was a poor prognosis factor in patients with GC. Finally, the CYT score was higher in a responder to anti‐PD‐1 therapy compared to nonresponders.ConclusionThe CYT score reflects antitumor immunity and predicts clinical outcome in GC patients.

ORAI2 Promotes Gastric Cancer Tumorigenicity and Metastasis through PI3K/Akt Signaling and MAPK-Dependent Focal Adhesion Disassembly.

The ubiquitous second messenger Ca2+ has long been recognized as a key regulator in cell migration. Locally confined Ca2+, in particular, is essential for building front-to-rear Ca2+ gradient, which serves to maintain the morphologic polarity required in directionally migrating cells. However, little is known about the source of the Ca2+ and the mechanism by which they crosstalk between different signaling pathways in cancer cells. Here, we report that calcium release-activated calcium modulator 2 (ORAI2), a poorly characterized store-operated calcium (SOC) channel subunit, predominantly upregulated in the lymph node metastasis of gastric cancer, supports cell proliferation and migration. Clinical data reveal that a high frequency of ORAI2-positive cells in gastric cancer tissues significantly correlated with poor differentiation, invasion, lymph node metastasis, and worse prognosis. Gain- and loss-of-function showed that ORAI2 promotes cell motility, tumor formation, and metastasis in both gastric cancer cell lines and mice. Mechanistically, ORAI2 mediated SOC activity and regulated tumorigenic properties through the activation of the PI3K/Akt signaling pathways. Moreover, ORAI2 enhanced the metastatic ability of gastric cancer cells by inducing FAK-mediated MAPK/ERK activation and promoted focal adhesion disassembly at rear-edge of the cell. Collectively, our results demonstrate that ORAI2 is a novel gene that plays an important role in the tumorigenicity and metastasis of gastric cancer. SIGNIFICANCE: These findings describe the critical role of ORAI2 in gastric cancer cell migration and tumor metastasis and uncover the translational potential to advance drug discovery along the ORAI2 signaling pathway.

RAI14 Regulated by circNFATC3/miR-23b-3p axis Facilitates Cell Growth and Invasion in Gastric Cancer

Circular RNAs (circRNAs) have been proved to act crucial roles in multiple malignancies including gastric cancer (GC). Retinoic acid induced 14 (RAI14) acts as an oncogene in human cancers, but the underlying mechanisms by which RAI14 is regulated by circRNA/miRNA axis remain elusive. The clinical value of RAI14, miR-23b-3p and circNFATC3 was estimated by The Cancer Genome Atlas and fluorescence in situ hybridization. The interplay between miR-23b-3p and RAI14 or circNFATC3 was determined by qRT-PCR, Western blot, luciferase gene report and RIP assays. Biological function assays and a subcutaneous xenograft model were executed to unveil the role of circNFATC3/miR-23b-3p/RAI14 axis in GC cells. As a consequence, upregulation of RAI14 and circNFATC3 or downregulation of miR-23b-3p was associated with poor prognosis in patients with GC. Restored miR-23b-3p depressed cell proliferation, colony formation, and cell invasion by targeting RAI14, whereas RAI14 facilitated cell progression and reversed the anti-tumor effects of miR-23b-3p in GC cells. Then, circNFATC3 had a co-localization with miR-23b-3p in the cytoplasm in GC tissue cells and could act as a sponge of miR-23b-3p in GC cell line. Silencing of circNFATC3 inhibited cell growth and in vivo tumorigenesis by upregulating miR-23b-3p and downregulating RAI14. In conclusion, our findings indicated that RAI14 facilitated cell growth and invasion and was regulated by circNFATC3/miR-23b-3p axis in GC.

Increased regulatory B cells are involved in immune evasion in patients with gastric cancer

Accumulating evidence has indicated that immune regulatory cells are involved in the establishment of tumoral immune evasion. However, the role of regulatory B cells (Bregs) in this remains unclear. Here, we identified a role for Bregs in immune evasion in gastric cancer (GC) patients. The frequency of peripheral Bregs was significantly higher in GC patients than in healthy controls (P = 0.0023). Moreover, the frequency of CD19+CD24hiCD27+ B cells in GC tissue was significantly higher than in peripheral blood and healthy gastric tissue. Carboxyfluorescein succinimidyl ester labeling revealed that CD19+CD24hiCD27+ B cells could suppress the proliferation of autologous CD4+ T cells. Moreover, CD19+CD24hiCD27+ B cells inhibited the production of interferon-gamma by CD4+ T cells. Double staining immunohistochemistry of interleukin-10 and CD19 revealed 5-year overall survival rates of 65.4% and 13.3% in BregLow and BregHigh groups, respectively (P < 0.0001). Multivariate analysis indicated that the frequency of Bregs was an independent prognostic indicator in GC patients. Taken together, our results show the existence of Bregs in GC tissue, and indicate that they are significantly correlated with the prognosis of GC patients.

Effect of p-PAQR3Thr32 on PD-L1 expression and immune evasion in gastric cancer.

e15571 Background: Therapies targeted to the immune checkpoint mediated by PD-1 and PD-L1 show antitumor activity in some solid tumors. We have now examined PD-L1 expression and its regulation in gastric cancer with p-PAQR3Thr32 protein. Methods: The expression of PD-L1 at the protein and mRNA levels in gastric cancer cell lines was examined by flow cytometry, real-time RT-PCR and western blot analysis, respectively. The expression of PD-L1 and p-PAQR3Thr32 protein in 319 surgically resected gastric cancer specimens was evaluated by immunohistochemical analysis. Results: The PD-L1 expression level was higher in gastric cancer cell lines positive for p-PAQR3Thr32 protein induced by glucose starvation than in those negative for the p-PAQR3Thr32 protein. Forced expression of p-PAQR3Thr32 protein in gastric cancer cells markedly increased PD-L1 expression, whereas endogenous PD-L1 expression in p-PAQR3Thr32 protein positive gastric cancer cells was attenuated by treatment with PAQR3 siRNAs. Furthermore, expression of PD-L1 was downregulated by inhibitors of the IRF1 and STAT1 in IFNs-PDL1 signaling pathway in gastric cancer cells positive for p-PAQR3Thr32 protein. At clinical tissue level, the expression level of PD-L1 was positively associated with the presence of p-PAQR3Thr32 protein in gastric cancer specimens. Moreover, the expression level of p-PAQR3Thr32 protein was negatively correlated with CD3, CD8, GZMA (CD8 T cell secretory factor) and positively correlated with CD68 (macrophage marker). Conclusions: Our findings that p-PAQR3Thr32 protein induced by glucose deficiency upregulate PD-L1 by activating IFNs-PDL1 signaling pathway in gastric cancer reveal a direct link between p-PAQR3Thr32 protein and PD-L1 expression. It is suggested that p-PAQR3Thr32 protein may be involved in tumor immunosuppression by inhibiting the proliferation and activity of CD8 T cells in gastric cancer tissues.

Expression of TWIST1 and CD44 as diagnostic and prognostic biomarkers in patients with gastric cancer

Objective The aim of this study was to investigate the association of TWIST1 and CD44 in gastric cancer (GC) with clinical parameters and their relation to prognosis, which may be beneficial for targeted therapeutic strategies in the future. Materials and methods The material of this work consisted of 40 primary GC specimens from patients who underwent radical gastrectomy. Patients who received neoadjuvant chemotherapy or chemoradiotherapy, those who presented with other cancers at the same time, or the patients with incomplete clinical data were excluded from the study. Hematoxylin and eosin-stained sections from all cases were re-evaluated and further stained immunohistochemically using antibodies against TWIST1 and CD44. Results TWIST1 and CD44-positive expressions were significantly increased in GC cases of diffuse type (P=0.019 and 0.002, respectively). Moreover, there was a statistically significant correlation between both markers and tumor grade, stage, and lymphovascular invasion (P=0.027 and 0.010, P=0.002 and 0.012, and P=0.001 and 0.005, respectively). A statistically significant correlation was found between TWIST1 and CD44 expressions in GCs (P=0.000). Conclusion The presence of TWIST1-positive carcinoma cells and CD44-positive cancer stem-like cells in GC tissue can be used as a diagnostic tool for GC and regarded as a marker of poor prognosis in patients with GC, which may provide potential targets for GC therapy.

EDD1 predicts prognosis and regulates gastric cancer growth in vitro and in vivo via miR-22.

Gastric cancer is the most common digestive malignant tumor worldwild. EDD1 was reported to be frequently amplified in several tumors and played an important role in the tumorigenesis process. However, the biological role and potential mechanism of EDD1 in gastric cancer remains poorly understood. In this study, we are aim to investigate the effect of EDD1 on gastric cancer progression and to explore the underlying mechanism. The results showed the significant up-regulation of EDD1 in -gastric cancer cell tissues and lines. The expression level of EDD1 was also positively associated with advanced clinical stages and predicted poor overall patient survival and poor disease-free patient survival. Besides, EDD1 knockdown markedly inhibited cell viability, colony formation, and suppressed tumor growth. Opposite results were obtained in gastric cancer cells with EDD1 overexpression. EDD1 knockdown was also found to induce gastric cancer cells apoptosis. Further investigation indicated that the oncogenic role of EDD1 in regulating gastric cancer cells growth and apoptosis was related to its PABC domain and directly through targeting miR-22, which was significantly down-regulated in gastric cancer tissues. Totally, our study suggests that EDD1 plays an oncogenic role in gastric cancer and may be a potential therapeutic target for gastric cancer.

A high number of IgG4-positive cells in gastric cancer tissue is associated with tumor progression and poor prognosis.

IgG4-related disease is a newly defined disease characterized by elevated serum IgG4 levels and infiltration of affected organs by IgG4-positive plasma cells. Recently, increased IgG4 levels were reported to be closely related with malignancy. To assess the relationship between IgG4 and the progression of gastric cancer, we immunohistochemically stained in this study gastric cancer tissue samples for IgG4-positive cells using an anti-IgG4 antibody. In addition, pre- and postoperative serum concentrations of IgG4 were measured, using an enzyme-linked immunosorbent assay. In gastric cancer samples, the number of CD138-positive plasma cells was significantly lower and the number of IgG4-positive cells significantly higher than in non-cancerous gastric mucosa. The number of IgG4-positive cells was significantly correlated with gross tumor appearance, tumor depth, lymph node metastasis, venous invasion, and lymphatic invasion. Prognosis was significantly poorer in patients with a high number of IgG4-positive cells than in those with a low number. Multivariate analysis indicated that both the number of IgG4-positive cells and the depth of tumor invasion were independently prognostic of survival. In conclusion, in gastric cancer, the number of IgG4-positive cells is increased and this is closely associated with gastric cancer progression.

Clinical relevance of the number of interleukin-17-producing CD 8+ T cells in patients with gastric cancer.

There is accumulating evidence that inflammation is linked to cancer development and progression. Interleukin-17 (IL-17), an inflammatory cytokine, is produced by CD 8+ T cells (Tc17 cells); however, the specific role of Tc17 cells in tumor immunity against gastric cancer remains unclear. The prevalence of Tc17 cells in both peripheral blood mononuclear cells and gastric tissue was evaluated by multicolor flow cytometry and the concentration of IL-17 in sera was quantitated by an enzyme-linked immunosorbent assay. Circulating Tc17 cells were significantly more numerous in gastric cancer patients than in controls, and significantly more numerous before surgery than after surgery. IL-17 concentrations in gastric cancer patients and healthy controls were 0.51 ± 0.54 and 0.084 ± 0.084 pg/mL, respectively, with this difference being significant. The percentage of Tc17 cells was significantly related to serum IL-17 concentration. Tc17 cells were significantly more numerous than peripheral blood mononuclear cells in gastric cancer tissue. Furthermore, Tc17 cells were more numerous in cancerous gastric tissue than in normal gastric tissue. Tc17 cells may be the main source of IL-17 in gastric cancer patients and thus involved in the progression of gastric cancer.

Regulatory effects of miRNA on gastric cancer cells.

The present study aimed to screen the regulatory mechanism of microRNA (miR/miRNA) typing on gastric cancer cells in gastric cancer tissues. In total, 46 patients who underwent gastric resection in Xiangya Hospital of Central-South University (Changsha, Hunan, China) between January and December 2012 were selected. Gastric cancer cells were obtained for RNA extraction, and miRNAs were detected by quantitative polymerase chain reaction. Compared with the expression levels in the normal gastric mucosa, the expression levels of miR-9, miR-433, miR-19b and miR-370 were downregulated; the differences was statistically significant, except for miR-19b (P<0.05). miRNAs play a regulative role in the occurrence and development of gastric cancer, and changes in their expression provide a basis for the diagnosis of this disease.

Increased apoptosis and elevated Fas expression in circulating natural killer cells in gastric cancer patients

Immune cells undergo extensive apoptosis in patients with cancer, which may be related to immune evasion by cancerous cells. The present study was designed to investigate the relationship between natural killer (NK) cell apoptosis and Fas expression in gastric cancer patients. NK cell apoptosis and Fas expression were evaluated by multicolor flow cytometry. Soluble Fas ligand (sFasL) was quantitated by enzyme-linked immunosorbent assay. The frequency of apoptotic NK cells in gastric cancer patients was significantly higher than in normal controls (p = 0.0016). Moreover, their frequency was related to the progression of gastric cancer. Fas-positive NK cells were significantly more common in gastric cancer patients compared with normal controls (p = 0.034). Furthermore, Fas expression was closely related to the frequency of NK cell apoptosis (r = 0.6, p < 0.0001). The frequency of tumor-infiltrating NK cell apoptosis was significantly higher than that of circulating NK cell apoptosis (p = 0.035). Furthermore, Fas-positive NK cells in gastric cancer tissues occurred significantly more often than in peripheral blood (p = 0.029). FasL concentration in gastric cancer patients was lower than that in normal controls, and the difference tended to be significant (p = 0.057). Apoptotic circulating NK cells significantly decreased after surgery compared to before surgery (p = 0.023). Furthermore, Fas expression on circulating NK cells also significantly decreased after surgery compared with before surgery (p = 0.021). Upregulation of Fas expression on NK cells is related to increased apoptosis of circulating NK cells in gastric cancer patients.

Presence of S100A9-positive inflammatory cells in cancer tissues correlates with an early stage cancer and a better prognosis in patients with gastric cancer

BackgroundS100A9 was originally discovered as a factor secreted by inflammatory cells. Recently, S100A9 was found to be associated with several human malignancies. The purpose of this study is to investigate S100A9 expression in gastric cancer and explore its role in cancer progression.MethodsS100A9 expression in gastric tissue samples from 177 gastric cancer patients was assessed by immunohistochemistry. The expression of its dimerization partner S100A8 and the S100A8/A9 heterodimer were also assessed by the same method. The effect of exogenous S100A9 on motility of gastric cancer cells AGS and BGC-823 was then investigated.ResultsS100A9 was specifically expressed by inflammatory cells such as macrophages and neutrophils in human gastric cancer and gastritis tissues. Statistical analysis showed that a high S100A9 cell count (> = 200) per 200x magnification microscopic field in cancer tissues was predictive of early stage gastric cancer. High S100A9-positive cell count was negatively correlated with lymph node metastasis (P = 0.009) and tumor invasion (P = 0.011). S100A9 was identified as an independent prognostic predictor of overall survival of patients with gastric cancer (P = 0.04). Patients with high S100A9 cell count were with favorable prognosis (P = 0.021). Further investigation found that S100A8 distribution in human gastric cancer tissues was similar to S100A9. However, the number of S100A8-positive cells did not positively correlate with patient survival. The inflammatory cells infiltrating cancer were S100A8/A9 negative, while those in gastritis were positive. Furthermore, exogenous S100A9 protein inhibited migration and invasion of gastric cancer cells.ConclusionsOur results suggested S100A9-positive inflammatory cells in gastric cancer tissues are associated with early stage of gastric cancer and good prognosis.

Decreased number and reduced NKG2D expression of Vδ1 γδ T cells are involved in the impaired function of Vδ1 γδ T cells in the tissue of gastric cancer

In cancer patients, impaired function of immune cells--such as CD8(+) T cells, NK cells, and dendritic cells--reportedly results in tumor progression. Although γδ T cells also play a critical role in tumor defense, their function remains unclear in cancer patients. The frequency and function of γδ T cells in peripheral blood, normal gastric mucosa, and cancer tissue were evaluated by multicolor flow cytometry. We also determined NKG2D expression on γδ T cells in gastric cancer patients. The frequency of Vδ1 γδ T cells in gastric cancer tissue is significantly lower than in normal gastric mucosa; however, differences in the frequencies of Vδ2 and Vγ9 γδ T cells between normal gastric mucosa and gastric cancer tissue were not statistically significant. The Vδ1 γδ T cells from gastric cancer tissue produce significantly less IFN-γ than those from normal gastric mucosa do. Expression of NKG2D on Vδ1 γδ T cells from gastric cancer tissue was significantly lower than in normal gastric mucosa. We also found a significant correlation between NKG2D expression and IFN-γ production of Vδ1 γδ T cells in gastric cancer tissue. Vδ1 γδ T cells show decreased frequency and impaired function in gastric cancer tissue, for which decreased NKG2D expression might be one of the mechanisms. Modalities specifically targeting NKG2D in Vδ1 γδ T cells may provide a breakthrough treatment for gastric cancer patients.

Expression of MMP-3 and TIMP-3 in gastric cancer tissue and its clinical significance

The present study aimed to investigate the expression of matrix metalloproteinase-3 (MMP-3) and the tissue inhibitor of metalloproteinase-3 (TIMP-3) in gastric cancer tissue, as well as to analyze the correlation between their expression and the occurrence of gastric cancer. Immunohistochemistry was used to determine the expression of MMP-3 and TIMP-3 in the gastric cancer tissue from 18 patients with early-stage gastric cancer (early-stage group) and 26 patients with advanced-stage gastric cancer (advanced-stage group). Transmission electron microscopy (TEM) was used to observe the lymphocytes and tumor cells in gastric cancer tissue. The results showed that the expression of TIMP-3 was significantly higher, whereas that of MMP-3 and MMP-3/TIMP-3 was lower in gastric cancer tissue of the early-stage group than in that of the advanced-stage group (P<0.05). The TEM images revealed increased lymphocytes and inconspicuous tumor cells penetrating the basement membrane in gastric cancer tissue of the early-stage group, and decreased lymphocytes and obvious tumor cells penetrating the basement membrane in the advanced-stage group. In conclusion, MMP-3 and TIMP-3 may be used as indices for the invasion and metastasis of gastric cancer and possess marked clinical significance in the prognostic judgment of gastric cancer.

Conversion of intratumoral regulatory T cells by human gastric cancer cells is dependent on transforming growth factor‐β1

Regulatory T cells (Treg) inhibits immune responses mediated by T cells. This study aimed to investigate whether Treg are accumulated in human gastric cancer tissue and the mechanism of Treg induction by gastric cancer cells. Tissue infiltrated leukocytes from gastric adenocarcinomas were subjected to flow cytometry and immunohistochemistry. Percentage, phenotype, function, and clinical relevance of Treg were analyzed. TGF-β1 production by cancer cells was determined by Western blot and in vitro co-culture experiments were performed to mimic gastric cancer microenvironment. The percentages of CD4(+) Foxp3(+) T cells in gastric cancer tissues were significantly higher than those from adjacent non-tumor gastric tissues (P < 0.05). The results of classical Treg phenotype and proliferation assay supported that the elevated CD4(+) Foxp3(+) T cells represents a suppressive Treg population. High proportion of Treg is correlated to advance TNM stage and reduced survival. Primary gastric cancer cells produced abundance of TGF-β1 which was responsible for conversion of Treg. The proportion of functional Treg is elevated in human gastric cancer and related to poor prognosis. Gastric cancer cells directly convert CD4(+) naive T cells to Treg by TGF-β1, suggesting a possible mechanism through which tumor cells evade the immune system.

Decreased NKG2D expression on NK cells correlates with impaired NK cell function in patients with gastric cancer

Although malignant diseases are known to be associated with immune suppression, the detailed mechanisms involved are still unknown. NKG2D is an activating cell surface receptor expressed by natural killer (NK) cells and CD8+ T cells, and the engagement of NKG2D is extremely important for NK cell activation. Although decreased NKG2D expression on NK cells is closely related to immune evasion by some cancers, the immunopathological importance of this phenomenon in gastric cancer patients remains unclear. NKG2D expression on NK cells was determined, using multicolor flow cytometry, to investigate the mechanisms responsible for immune evasion in gastric cancer patients. NKG2D expression on NK cells from gastric cancer patients was significantly lower than that in healthy controls. Also, NKG2D expression in advanced gastric cancer was significantly lower than that in early gastric cancer. NK cells from patients with lymph node metastasis expressed significantly lower levels of NKG2D than the NK cells from those without lymph node metastasis, and NKG2D expression on NK cells in gastric cancer tissue was significantly lower than that of circulating NK cells. NKG2D expression on NK cells obtained from cancer patients was restored after 48h in culture with RPMI containing 10% AB serum. Furthermore, NKG2D expression on NK cells obtained after surgery was significantly higher than that before surgery. Decreased NKG2D expression on NK cells may be one of the key mechanisms responsible for NK cell dysfunction in gastric cancer.