Clinical significance of the B7-H4 coregulatory molecule as a novel prognostic marker in gastric cancer

Prognostic Value of B7H4 Expression in Patients with Solid Cancers: A Systematic Review and Meta-Analysis

V-set domain-containing T-cell activation inhibitor 1 (aliases VTCN1, B7H4) participates in tumour immune escape by delivering inhibitory signals to T cells. The purpose of this article was to assess the B7H4 prognostic value in solid cancers. Three databases were searched for relevant articles. The main endpoints were overall survival (OS), disease-specific survival (DSS), progression-free survival (PFS), recurrence-free survival (RFS), and disease-free survival (DFS). Appropriate hazard ratios (HRs) were pooled. The R studio software (version 4.0.3) was used for data analysis. Thirty-one studies met the inclusion criteria. High expression of B7H4 was associated with worse OS (HR = 1.52, 95% CI: 1.37-1.68) but not with DSS (HR = 1.14, 95% CI: 0.49-2.63), RFS (HR = 1.77, 95% CI: 0.75-4.18), DFS (HR = 1.29, 95% CI: 0.8-2.09), or PFS (HR = 1.71, 95% CI: 0.91-3.2) in patients with solid cancers. High expression of B7H4 is associated with a poorer prognosis in patients with solid cancers. B7H4 is a promising prognostic biomarker and immunotherapeutic target for various solid cancers because of its activity in cancer immunity and tumourigenesis.

Clinical significance of blocking novel immune checkpoint B7-H4 in urothelial carcinoma of bladder as a potential therapeutic target

Urothelial Carcinoma of Bladder is complex disease with high mortality and recurrence rates. Current standard regimes have exhibited anti-tumor activity but still, a proportion of patients are non-responsive or in-eligible to receive such treatments. Immune checkpoints have emerged as potential class of therapeutics to be tested in UCB patients. Clinical trials targeting PD-1/PD-L1 axis have been tested in UCB but still a proportion of patients are non-responsive to it which stresses upon identifying new targets. New immune checkpoint B7-H4 has been shown to negatively regulate T cell activity in cancer and is a poor prognostic factor in various solid tumors. In this study we assessed the novel immune checkpoint B7-H4 status in UCB patients. We observed elevated expression of B7-H4 and PD-L1 on CD8+ T cells in circulation of UCB patients. Relative mRNA expression and immunohistochemistry displayed upregulation in bladder tumor tissue. Increased expression of B7-H4 along with PD-L1 in periphery and tumor of UCB patients highlights involvement of B7-H4 in disease progression. Combinatorial blocking of B7-H4 and PD-L1 enhanced IFN-γ and granzyme B in CD8+ T cells functional T cell immune response in UCB patients. Also, B7-H4 was significantly associated with clinico-pathological parameters. Our findings highlight B7-H4 as potential therapeutic target for treatment of UCB patients in future after further validation.

The stromal tumor-infiltrating lymphocytes, cancer stemness, epithelial-mesenchymal transition, and B7-H4 expression in ovarian serous carcinoma

BACKGROUND

B7-H4 is expressed in various types of cancers and its expression inversely correlates with the degree of tumor-infiltrating lymphocytes (TILs). Studies have shown the relationship between B7-H4, cancer stem cell (CSC) properties, and epithelial-mesenchymal transition (EMT) in various cancers. However, very few studies have investigated the relationship between B7-H4, TILs, cancer stemness, and EMT in epithelial ovarian cancer (EOC). The present study aimed to elucidate whether B7-H4 is involved in immune evasion and examine whether B7-H4 is associated with cancer stemness or EMT in ovarian serous carcinoma, the most common type of EOC. The clinical significance of B7-H4 was also investigated to evaluate its potential as a therapeutic target.

METHODS

A total of 145 patients included in this study. The degree of stromal TILs was evaluated using hematoxylin and eosin (H&E)-stained slides. Immunohistochemical analysis of B7-H4, CSC-related biomarkers (CD24, CD44s, CD133, and ALDH1), and EMT-related biomarkers (E-cadherin, N-cadherin, and vimentin) was performed using tissue microarray. qRT-PCR for VTCN1, CD24, CD44, PROM1, ALDH1, CDH1, CDH2, and VIM genes was performed on 38 frozen tissue samples. The mRNA expression levels were analyzed using Gene Expression Profiling Interactive Analysis (GEPIA) online analysis tool.

RESULTS

B7-H4 protein expression positively correlated with the degree of stromal TILs. CD24, CD44s, and CD133 expression showed a positive correlation with B7-H4 expression at both the protein and mRNA levels, but ALDH1 correlated only at the protein level. E-cadherin expression was positively correlated with B7-H4 expression at both the protein and mRNA levels. N-cadherin and vimentin expression was inversely related to B7-H4 expression only at the mRNA level. B7-H4 positive patients were associated with higher tumor grade and lower overall survival rate than B7-H4 negative patients, especially in ovarian serous carcinoma with low stromal TILs.

CONCLUSIONS

The present study demonstrates that B7-H4 may not be involved in the immune evasion mechanism, but is involved in cancer stemness and mesenchymal-epithelial transition. In addition, B7-H4 may be a therapeutic target for the treatment of ovarian serous carcinoma, especially with low stromal TILs.

V-set domain containing T-cell activation inhibitor-1 (VTCN1): A potential target for the treatment of autoimmune diseases

Autoimmunity eventuates when the immune system attacks self-molecules as a result of the breakdown in immune tolerance. Targeting autoimmune diseases via immunomodulation has become an essential strategy in today's era. A B7 superfamily member immune checkpoint, the V-set domain containing T-cell activation inhibitor-1 (VTCN1), also known as B7-H4, B7S1, and B7x, is involved in negatively regulating T-cell activation. VTCN1 transcript has been reported in various lymphoid and non-lymphoid tissues, but its protein expression is restricted, indicating its translational regulation. Dysregulation of VTCN1 has resulted in the exacerbation of various autoimmune diseases. Moreover, increased soluble form of VTCN1 in the patient's sera positively correlates with the disease progression and severity. The current review summarizes all the reports till date, unfolding the role of VTCN1 in various autoimmune diseases and its therapeutic potential.

Expression of Immune Checkpoints in Malignant Tumors: Therapy Targets and Biomarkers for the Gastric Cancer Prognosis

To increase the effectiveness of anticancer therapy based on immune checkpoint (IC) inhibition, some ICs are being investigated in addition to those used in clinic. We reviewed data on the relationship between PD-L1, B7-H3, B7-H4, IDO1, Galectin-3 and -9, CEACAM1, CD155, Siglec-15 and ADAM17 expression with cancer development in complex with the results of clinical trials on their inhibition. Increased expression of the most studied ICs—PD-L1, B7-H3, and B7-H4—is associated with poor survival; their inhibition is clinically significant. Expression of IDO1, CD155, and ADAM17 is also associated with poor survival, including gastric cancer (GC). The available data indicate that CD155 and ADAM17 are promising targets for immune therapy. However, the clinical trials of anti-IDO1 antibodies have been unsatisfactory. Expression of Galectin-3 and -9, CEACAM1 and Siglec-15 demonstrates a contradictory relationship with patient survival. The lack of satisfactory results of these IC inhibitor clinical trials additionally indicates the complex nature of their functioning. In conclusion, in many cases it is important to analyze the expression of other participants of the immune response besides target IC. The PD-L1, B7-H3, B7-H4, IDO1 and ADAM17 may be considered as candidates for prognosis markers for GC patient survival.

The Positive and Negative Immunoregulatory Role of B7 Family: Promising Novel Targets in Gastric Cancer Treatment

Gastric cancer (GC), with a heterogeneous nature, is the third leading cause of death worldwide. Over the past few decades, stable reductions in the incidence of GC have been observed. However, due to the poor response to common treatments and late diagnosis, this cancer is still considered one of the lethal cancers. Emerging methods such as immunotherapy with immune checkpoint inhibitors (ICIs) have transformed the landscape of treatment for GC patients. There are presently eleven known members of the B7 family as immune checkpoint molecules: B7-1 (CD80), B7-2 (CD86), B7-H1 (PD-L1, CD274), B7-DC (PDCD1LG2, PD-L2, CD273), B7-H2 (B7RP1, ICOS-L, CD275), B7-H3 (CD276), B7-H4 (B7x, B7S1, Vtcn1), B7-H5 (VISTA, Gi24, DD1α, Dies1 SISP1), B7-H6 (NCR3LG1), B7-H7 (HHLA2), and Ig-like domain-containing receptor 2 (ILDR2). Interaction of the B7 family of immune-regulatory ligands with the corresponding receptors resulted in the induction and inhibition of T cell responses by sending co-stimulatory and co-inhibitory signals, respectively. Manipulation of the signals provided by the B7 family has significant potential in the management of GC.

B7-H4 induces epithelial-mesenchymal transition and promotes colorectal cancer stemness

B7-H4 is a unique negative regulator of T cells that is typically significantly overexpressed in various carcinomas and is associated with poor prognosis. However, the effects of B7-H4 expression on epithelial-mesenchymal transition (EMT) and cancer stemness of colorectal cancer (CRC) are not entirely clear. In the present study, we used tissue samples from 98 patients with CRC and CRC cell lines to determine the clinicopathological significance of B7-H4 in CRC and its effects on CRC stemness. We performed immunohistochemical staining; immunofluorescence imaging; western blotting; and tumor sphere formation, wound healing, transwell migration, and in vivo tumorigenesis assays. B7-H4 expression was upregulated in CRC tissues and was associated with lymph node metastasis, distant metastasis, clinical stage, a shorter overall survival rate, and disease-free survival rate. Cox regression analyses indicated that B7-H4 is an independent poor prognostic factor for CRC. In addition, B7-H4 expression was correlated with the expression of EMT-related proteins and cancer stemness-related proteins. Moreover, immunohistochemical and immunofluorescence analyses revealed that B7-H4 was correlated with CD133 and CD44 expression levels in both CRC tissues and HT29 and HCT116 cell lines. Conversely, B7-H4 knockdown downregulated the expression of EMT- and cancer stemness-related proteins, while inhibiting tumor spheroid formation, cell migration, and invasion of CRC cell lines. These results indicate that B7-H4 can promote EMT and may be a novel stem cell marker, suggesting its potential as a prognostic biomarker for CRC.

Antibody targeting of B7-H4 enhances the immune response in urothelial carcinoma

Patients with locally advanced and metastatic urothelial carcinoma have a low survival rate (median 15.7 months, 13.1-17.8), with only a 23% response rate to monotherapy treatment with anti-PDL1 checkpoint immunotherapy. To identify new therapeutic targets, we profiled the immune regulatory signatures during murine cancer development using the BBN carcinogen and identified an increase in the expression of the T cell inhibitory protein B7-H4 (VTCN1, B7S1, B7X). B7-H4 expression temporally correlated with decreased lymphocyte infiltration. While the increase in B7-H4 expression within the bladder by CD11b+ monocytes is shared with human cancers, B7-H4 expression has not been previously identified in other murine cancer models. Higher expression of B7-H4 was associated with worse survival in muscle-invasive bladder cancer in humans, and increased B7-H4 expression was identified in luminal and luminal-papillary subtypes of bladder cancer. Evaluation of B7-H4 by single-cell RNA-Seq and immune mass cytometry of human bladder tumors found that B7-H4 is expressed in both the epithelium of urothelial carcinoma and CD68+ macrophages within the tumor. To investigate the function of B7-H4, treatment of human monocyte and T cell co-cultures with a B7-H4 blocking antibody resulted in enhanced IFN-γ secretion by CD4+ and CD8+ T cells. Additionally, anti-B7-H4 antibody treatment of BBN-carcinogen bladder cancers resulted in decreased tumor size, increased CD8+ T cell infiltration within the bladder, and a complimentary decrease in tumor-infiltrating T regulatory cells (Tregs). Furthermore, treatment with a combination of anti-PD-1 and anti-B7-H4 antibodies resulted in a significant reduction in tumor stage, a reduction in tumor size, and an increased level of tumor necrosis. These findings suggest that antibodies targeting B7-H4 may be a viable strategy for bladder cancers unresponsive to PD-1 checkpoint inhibitors.

B7-H4 is a potential prognostic biomarker of prostate cancer

B7-H4 is a member of B7 family which regulates immune responses by delivering costimulatory signals. However, it negatively regulates T cell-mediated immunity and may play an important role in tumor immune evasion. Although several studies have been reported that expression of B7-H4 is elevated in the several types of human cancer with a poor clinical outcome, its clinical significance in the prostate cancer (PCa) has not been well studied. In this study, we investigated the clinical significance of B7-H4 in human PCa and determined if B7-H4 expression is associated with the cancer cell stemness in PCa. Our studies show that expression of B7-H4 is correlated with the pathologic tumor (pT) stage and the clinical stage of PCa. The Kaplan-Meier survival analysis revealed that PCa patients with high expression of B7-H4 exhibits a shorter overall survival (OS) rate. Univariate and multivariate Cox regression analysis indicated that B7-H4 is an independent poor prognostic factor of PCa. In addition, the expression of B7-H4 is correlated with the cancer cell stemness associated genes expression in PCa. Further, our studies show that B7-H4 regulates cancer cell stemness associated genes expression and effects on the cell cycle and PI3K/Akt signaling related genes expression in PCa. These results indicate that B7-H4 expression is associated with cancer cell stemness, and B7-H4 is a potential prognostic biomarker and a therapeutic target of PCa.

B7-H4, a promising target for immunotherapy

The coinhibitory molecule B7-H4, an important member of the B7 family, is abnormally expressed in tumors, inflammation and autoimmune diseases. B7-H4 negatively regulates T cell immune response and promotes immune escape by inhibiting the proliferation, cytokine secretion, and cell cycle of T cells. Moreover, B7-H4 plays an extremely important role in tumorigenesis and tumor development including cell proliferation, invasion, metastasis, anti-apoptosis, etc. In addition, B7-H4 has the other biological functions, such as protection against type 1 diabetes (T1D) and islet cell transplantation. Therefore, B7-H4 has been identified as a novel marker or a therapeutic target for the treatment of tumors, inflammation, autoimmune diseases, and organ transplantation. Here, we summarized the expression profiles, physiological and pathological functions, and regulatory mechanisms of B7-H4, the signaling pathways involved, as well as B7-H4-based immunotherapy.

Diverse tumour susceptibility in Collaborative Cross mice: identification of a new mouse model for human gastric tumourigenesis

OBJECTIVE

The Collaborative Cross (CC) is a mouse population model with diverse and reproducible genetic backgrounds used to identify novel disease models and genes that contribute to human disease. Since spontaneous tumour susceptibility in CC mice remains unexplored, we assessed tumour incidence and spectrum.

DESIGN

We monitored 293 mice from 18 CC strains for tumour development. Genetic association analysis and RNA sequencing were used to identify susceptibility loci and candidate genes. We analysed genomes of patients with gastric cancer to evaluate the relevance of genes identified in the CC mouse model and measured the expression levels of ISG15 by immunohistochemical staining using a gastric adenocarcinoma tissue microarray. Association of gene expression with overall survival (OS) was assessed by Kaplan-Meier analysis.

RESULTS

CC mice displayed a wide range in the incidence and types of spontaneous tumours. More than 40% of CC036 mice developed gastric tumours within 1 year. Genetic association analysis identified Nfκb1 as a candidate susceptibility gene, while RNA sequencing analysis of non-tumour gastric tissues from CC036 mice showed significantly higher expression of inflammatory response genes. In human gastric cancers, the majority of human orthologues of the 166 mouse genes were preferentially altered by amplification or deletion and were significantly associated with OS. Higher expression of the CC036 inflammatory response gene signature is associated with poor OS. Finally, ISG15 protein is elevated in gastric adenocarcinomas and correlated with shortened patient OS.

CONCLUSIONS

CC strains exhibit tremendous variation in tumour susceptibility, and we present CC036 as a spontaneous laboratory mouse model for studying human gastric tumourigenesis.

B7x-from bench to bedside

B7x is an immune checkpoint molecule which belongs to the B7 family of ligands which includes PD-L1, PD-L2, B7-H3 and HHLA2. B7x belongs to the Immunoglobulin superfamily and its protein structure is similar to other members with a N terminus peptide, IgV and IgC like extracellular domain with four cysteine residues. Its receptor is yet to be identified. B7x inhibits T cell proliferation and expansion by IL-2 dependent and non-IL-2 dependent pathways. Even though high levels of B7x mRNA can be detected in most tissues its protein expression is highly limited suggesting significant post translational control. In vivo data, show that B7x plays an important role in limiting autoimmunity in the peripheral tissues and fine-tuning autoimmune responses. B7x is highly expressed in various cancers and in prostate cancer its expression is corelated with poorer outcomes. Local production of IL-6 and IL-10 in various cancers promotes B7x expression and tumor immune evasion. B7x is especially expressed in PD-L1 negative tumors suggesting that this may be an important method of immune evasion in these tumors. Currently drug development, targeting B7x through various mechanisms including monoclonal antibodies and antibody drug conjugates are in development in cancers and increasing B7x expression with fusion proteins in autoimmune diseases is underway.

B7H4 is associated with stemness and cancer progression in esophageal squamous cell carcinoma

B7H4 is overexpressed in human cancers and often correlates with poor clinical outcome. There is a lack of data on the role of B7H4 as a cancer stem cell (CSC) regulator in esophageal squamous cell carcinoma (ESCC) and its expression levels compared to other stemness genes in ESCC. In this study, we have assessed the expression of B7H4 and cancer stemness proteins in 156 paraffin-embedded ESCC tissue samples using immunohistochemistry as well as in ESCC cell lines using Western blotting and immunofluorescence imaging. The correlation of B7H4 expression with clinicopathological parameters, cell cycle regulating genes, and PI3K/Akt/NF-κB signaling genes was investigated. The expression of B7H4 in ESCC tissue was correlated with the primary tumor (pT) stage, stromal activity, and the expression of CD68 and HIF-1α. However, B7H4 expression was negatively associated with CD8+ T cell infiltration in ESCC tissues. Moreover, B7H4 was found to be strongly linked to prognostic factors leading to poor clinical outcome. B7H4-expressing cancer cells also expressed known cancer stemness proteins (Sox9, LSD1, Oct4, and LGR5). Moreover, B7H4, Sox9, LSD1, Oct4, and LGR5 were highly expressed in more poorly differentiated ESCC cell lines. Notably, B7H4 expression was positively associated with the expression of cell cycle regulators such as cyclin D1, p27, and PI3K/Akt/NFκB signaling proteins. B7H4 could be a novel cancer stem cell marker for the prognostic evaluation of ESCC patients as well as a potential therapeutic target against ESCC.

The association of human endogenous retrovirus-H long terminal repeat-associating protein 2 (HHLA2) expression with gastric cancer prognosis

Currently, immune checkpoint blockade against members of the B7/CD28 family is being used as a new molecular-targeted therapy, in patients with unresectable advanced or recurrent gastric cancer. Although human endogenous retrovirus-H long terminal repeat-associating protein 2 (HHLA2) is a novel molecule of the B7/CD28 family, the clinical impact of its expression remains uncertain in gastric cancer. Consequently, we examined HHLA2 expression in blood specimens from patients with gastric cancer, and investigated the relationship between its expression and clinicopathological factors to assess its potential power as a prognostic blood predictor. Untreated peripheral blood specimens were obtained from 111 patients with gastric cancer and 20 healthy volunteers. HHLA2 mRNA expression levels were determined using quantitative RT-PCR assay. Blood specimens obtained from patients with gastric cancer had significantly lower copies of HHLA2 mRNA than those obtained from healthy volunteers (P < 0.0001). Furthermore, HHLA2 expression was significantly correlated with the depth of tumor invasion (P = 0.0331), distant metastasis (P < 0.0001), and stage of disease (P = 0.0032). The 5-year survival rate was significantly higher in patients with high HHLA2 expression compared with the patients with low expression (P = 0.0001). These findings demonstrate that assessment of HHLA2 expression levels in the blood could be utilized to predict tumor aggressiveness in patients with gastric cancer.

New B7 Family Checkpoints in Human Cancers

T cells are the main effector cells in immune response against tumors. The activation of T cells is regulated by the innate immune system through positive and negative costimulatory molecules. Targeting immune checkpoint regulators such as programmed cell death 1 (PD-1)/PD-1 ligand 1 (PD-L1) and CTL antigen 4 (CTLA-4) has achieved notable benefit in a variety of cancers, which leads to multiple clinical trials with antibodies targeting the other related B7/CD28 family members. Recently, five new B7 family ligands, B7-H3, B7-H4, B7-H5, B7-H6, and B7-H7, were identified. Here we review recent understanding of new B7 family checkpoint molecules as they have come to the front of cancer research with the concept that tumor cells exploit them to escape immune surveillance. The aim of this article is to address the structure and expression of the new B7 family molecules as well as their roles in controlling and suppressing immune responses of T cells as well as NK cells. We also discuss clinical significance and contribution of these checkpoint expressions in human cancers. Mol Cancer Ther; 16(7); 1203-11. ©2017 AACR.

Prognostic role of B7-H4 in patients with non-small cell lung cancer: A meta-analysis

B7 homolog 4 (B7-H4) has been recently reported to be a prognostic marker in non-small cell lung cancer (NSCLC) in some studies. However, the results remained conflicting. Thus, we aimed to comprehensively assess the association between B7-H4 expression and prognosis of NSCLC patients by performing a meta-analysis. Relevant publications were thoroughly searched of PubMed, Embase, Web of Science and China National Knowledge Infrastructure (CNKI). The pooled odds ratios (ORs) and hazard ratios (HRs) with 95% confidence intervals (CIs) were applied to evaluate the effects. A total of 9 studies comprising 1444 patients were included in this meta-analysis. B7-H4 overexpression was associated with presence of lymph node metastasis (OR=3.59, 95%CI=2.39-5.38, p<0.001; fixed effect), advanced TNM stage (OR=2.36, 95%CI=1.2-4.67, p=0.013; random effect), and poor differentiation (OR=2.11, 95%CI=1.12-3.99, p=0.021; fixed effect). However, B7-H4 had no significant correlation with gender, age or histology in NSCLC. Furthermore, in a fixed effects model, the results indicated that B7-H4 overexpression was significantly associated with poor OS (HR=2.03, 95%CI=1.41-2.92, p<0.001). This meta-analysis demonstrated that high B7-H4 expression is an unfavorable prognostic factor in NSCLC. Because few studies were included for meta-analysis and almost all included studies were performed on Chinese patients, therefore; large scale prospective studies are needed to verify our results.

The prognostic value of B7-H4 in pancreatic cancer: Systematic review and meta-analysis

BACKGROUND

There were many reports suggesting that different kinds of tumors can express B7-H4; however, the prognostic value in cancer was still unclearly. Therefore, we conducted a meta-analysis to investigate the relationship between overexpression of B7-H4 with the prognostic value in pancreatic cancer patients.

MATERIALS AND METHODS

The Pubmed, Embase, Cochrane Library, Ovid, Web of Science, and Chinese research database (including CBM, CNKI, and WAN FANG) were searched for related literature published until October 12, 2017. The pooled odds ratios (ORs) and/or pooled hazard ratios (HRs) for clinical pathological factors and overall survival (OS) were calculated and analyzed using Stata software. To assess whether an individual study had an impact on the result, sensitivity analysis was performed for all included individual studies using the fixed-effects model. Publication bias was evaluated using Egger's and Begg's tests.

RESULTS

Data from 6 observational studies including 442 patients were summarized in this meta-analysis, and each study was eligible for inclusion based on included and exclude criteria. The pooled results indicated that the B7-H4 overexpression could predict the presentation of lymph node metastasis (OR = 3.94, 95% CI: 1.22-12.66, P = .022), advanced TNM stage (T = the extent of the primary tumor, N = regional lymph nodes, M = distant metastases) (III+IV vs I+II; OR = 7.63, 95% CI: 2.46-23.66, P < .001), and the poor OS (HR = 3.00, 95%CI = 2.20-4.10, P < .001) in PC patients.

CONCLUSIONS

This study reveals that high expression of B7-H4 is an unfavorable prognostic factor for patients with pancreatic cancer. These results may guide the clinical management of this patient population.

Prognostic role of high B7-H4 expression in patients with solid tumors: a meta-analysis

BACKGROUND

Recently, many studies have shown that B7-H4 exhibits altered expression in various cancers. We performed a meta-analysis to evaluate the prognostic role of B7-H4 expression in solid tumors.

RESULTS

Data from 18 observational studies and 2467 patients were summarized. An elevated baseline B7-H4 was significantly associated with worse OS (pooled HR = 1.79; 95% CI = 1.56-2.06). Differences across subgroups of tumor type, patients' ethnicity, analysis type, HR obtain method and cut-off value were not significant (PD = 0.313, PD = 0.716, PD = 0.896, PD = 0.290 and PD = 0.153, respectively). Furthermore, patients with high B7-H4 had a significantly shorter DFS (pooled HR = 2.12; 95%CI = 1.45-3.09).

MATERIALS AND METHODS

We searched PubMed, Embase and the Cochrane Library (last update by November 26, 2015) to identify studies assessing the effect of B7-H4 on survival of cancer patients. Pooled hazard ratios (HRs) for overall survival (OS) and disease-free survival (DFS) were estimated using fixed-effects models and random-effects models respectively.

CONCLUSIONS

This meta-analysis clarified that high B7-H4 expression in tissue was significantly associated with poor survival in patients with solid tumors. Future clinical studies are warranted to determine whether B7-H4 blockade has a favorable effect on disease recurrence and mortality.

Potential targeting of B7-H4 for the treatment of cancer

Observations noting the presence of white blood cell infiltrates within tumors date back more than a century, however the cellular and molecular mechanisms regulating tumor immunity continue to be elucidated. The recent successful use of monoclonal antibodies to block immune regulatory pathways to enhance tumor-specific immune responses for the treatment of cancer has encouraged the identification of additional immune regulatory receptor/ligand pathways. Over the past several years, a growing body of data has identified B7-H4 (VTCN1/B7x/B7S1) as a potential therapeutic target for the treatment of cancer. The potential clinical significance of B7-H4 is supported by the high levels of B7-H4 expression found in numerous tumor tissues and correlation of the level of expression on tumor cells with adverse clinical and pathologic features, including tumor aggressiveness. The biological activity of B7-H4 has been associated with decreased inflammatory CD4⁺ T-cell responses and a correlation between B7-H4-expressing tumor-associated macrophages and FoxP3⁺ regulatory T cells (Tregs) within the tumor microenvironment. Since B7-H4 is expressed on tumor cells and tumor-associated macrophages in various cancer types, therapeutic blockade of B7-H4 could favorably alter the tumor microenvironment allowing for antigen-specific clearance tumor cells. The present review highlights the therapeutic potential of targeting B7-H4.

B7-H4 as an independent prognostic indicator of cancer patients: a meta-analysis

The expression of B7-H4 was observed in a variety of tumors, however the prognostic value in cancer was still controversial. Therefore, we conducted this meta-analysis to explore the potential role of B7-H4 in cancer prognostic prediction. Twenty-seven studies including 3771 patients were brought into the analysis according to the inclusion and exclusion criteria. The pooled results demonstrated that elevated B7-H4 predicted a poor OS (HR = 1.93, 95% CI 1.71-2.18, P < 0.001) and DFS (HR = 1.84, 95% CI 1.46-2.33, P < 0.001). Subgroup analysis showed that races, tumor types, sample sources, analysis types, sources of HR and sample sizes exhibited non-significant distinctions with OS (P_S = 0.878, P_S = 0.143, P_S = 0.613, P_S = 0.639, P_S = 0.48 and P_S = 0.528, respectively). PubMed, Embase and the Cochrane Library were searched up to April 7, 2017, to recognize the available studies for assessing the association between B7-H4 and cancer patients’ outcome. We extracted the hazard ratio (HR), relative ratio (RR), odds ratio (OR) with their 95% confidence interval (CI) for overall survival (OS) or disease-free survival (DFS) as the effect size (ES) for the analysis. This meta-analysis demonstrates high expression of B7-H4 is a negative correlation with the outcome of cancer patients.

Novel B7-H4-mediated crosstalk between human non-Hodgkin lymphoma cells and tumor-associated macrophages leads to immune evasion via secretion of IL-6 and IL-10

Non-Hodgkin lymphoma (NHL) is an incurable lymphoproliferative cancer, and patients with NHL have a poor prognosis. The present study explored the regulatory mechanism of expression and possible roles of the immunosuppressive B7-H4 molecule in human NHL. For functional studies, NHL-reactive T cell lines were generated via the isolation of allogeneic CD3+ T cells from healthy donors and repeated in vitro stimulation with irradiated NHL cells isolated from patients. B7-H4 was found to be distributed in NHL cells and tissues, and its surface protein expression levels were further upregulated by the incubation of NHL cells with interleukin (IL)-6, IL-10, or interferon-γ. Additionally, the supernatants of tumor-associated macrophages (tMφs) upregulated B7-H4 surface expression by producing IL-6 and IL-10. B7-H4 expressed in NHL cells inhibited the cytotoxic activity of NHL-reactive T cells. Conversely, the inhibition of B7-H4 in NHL cells promoted T cell immunity and sensitized NHL cells to cytolysis. Furthermore, tMφs induced B7-H4 promoted NHL cell evasion of the T cell immune response. In conclusion, this study shows that NHL-expressed B7-H4 is an important immunosuppressive factor that inhibits host anti-tumor immunity to NHL. Targeting tumor-expressed B7-H4 may thus provide a new treatment strategy for NHL patients.

Clinical significance of circulating tumor cells in blood from patients with gastric cancer

Circulating tumor cells (CTC) have been focused on as a target for detecting occult tumors, predicting therapeutic responses and prognoses, and monitoring postoperative recurrence in the clinical management of patients with various malignancies, including gastric cancer. Recent advances in molecular diagnostic tools have contributed to high sensitivity and specificity for the detection of CTC. A conspicuous disparity exists in the incidence of CTC among studies. However, a close relationship has been reported between positivity for CTC and well‐known prognostic clinicopathological factors including depth of tumor invasion, lymph node metastasis, stage, and lymphatic and venous invasion in patients with gastric cancer. According to most studies published on the clinical impact of CTC, the presence of CTC negatively affects the prognosis of patients with gastric cancer. Moreover, the study of CTC based on a meta‐analysis demonstrated their importance as a poor prognostic indicator. In clinical management, pre‐ and post‐therapeutic monitoring of CTC using liquid biopsy may be useful for early detection of subclinical patients or disease recurrence, prediction of tumor progression, and administrative control of adjuvant chemotherapy. Although their functional properties remain unclear, molecular profiling of CTC may contribute to the development of personalized treatment that effectively inhibits tumor progression in patients with advanced gastric cancer. We herein review the clinical significance of CTC as a promising blood marker and therapeutic target in patients with gastric cancer.

Molecular Pathways: Evaluating the Potential for B7-H4 as an Immunoregulatory Target

With the clinical success of CTLA-4 and PD-1 blockade in treating malignancies, there is tremendous interest in finding new ways to augment antitumor responses by targeting other inhibitory molecules. In this review, we describe one such molecule. B7-H4, a member of the B7 family of immunoregulatory proteins, inhibits T cell proliferation and cytokine production through ligation of an unknown receptor expressed by activated T cells. Notably, B7-H4 protein expression is observed in a high proportion of patients' tumors across a wide variety of malignancies. This high expression by tumors in combination with its low or absent protein expression in normal tissues makes B7-H4 an attractive immunotherapeutic target. Preclinical investigation into B7-H4-specific chimeric antigen receptor (CAR) T cells, antibody-mediated blockade of B7-H4, and anti-B7-H4 drug conjugates has shown antitumor efficacy in mouse models. The first clinical trials have been completed to assess the safety and efficacy of a B7-H4 fusion protein in ameliorating rheumatoid arthritis. Clin Cancer Res; 23(12); 2934-41. ©2017 AACR.

Clinical impact of circulating tumor cells and therapy response in pancreatic cancer

BACKGROUND

Among gastrointestinal cancers, the prognosis of pancreatic cancer is one of the poorest, with a large number of patients being diagnosed with unresectable tumors at the first visit to a doctor. The aims of the present study were to investigate the circulating tumor cells (CTC) in peripheral blood in order to assess their clinical significance in patients with pancreatic cancer.

METHODS

Sixty-five patients with advanced pancreatic cancer were enrolled. Borderline resectable pancreatic tumor patients were 9, and Unresectable patients were 56. The CellSearch system was used to isolate and enumerate CTCs.

RESULTS

CTCs were identified in 21 out of 65 patients (32.3%) with only unresectable tumors. The overall survival rate was significantly lower in unresectable patients with than in those without CTCs (P = 0.0051). CTC positivity was significantly higher in patients with than in those without liver metastasis. A multivariate analysis identified the presence or absence of CTCs as an independent prognostic factor. Follow-up blood specimens were obtained from 40 patients treated with chemotherapy or chemoradiotherapy. The incidences of CTC positivity at three months after beginning of treatments in patients with progressive disease and stable disease or a partial response were 45.4% and 24.1%, respectively. The overall survival rate was significantly lower in patients with than in those without CTCs even after treatments (P = 0.045).

CONCLUSION

CTC numbers represents a useful tool for predicting prognoses and therapeutic responses to chemotherapy among patients with advanced pancreatic cancer.

Increased B7-H4 expression during esophageal squamous cell carcinogenesis is associated with IL-6/STAT3 signaling pathway activation in mice

B7-homolog 4 (B7-H4), one of the costimulatory molecules of the B7 family, has been reported to be widely expressed in multiple types of cancer tissues, and to be important in tumor progression and poor prognosis. However, the role of B7-H4 in esophageal precancerous lesions has not been elucidated yet. In the present study, a model of esophageal squamous cell carcinogenesis was established in 208 C57BL/6 mice by 4-nitroquinoline-1-oxide (4NQO) drinking water of mice, and the changes in the expression of B7-H4 during the whole pathological process were investigated. Hematoxylin and eosin staining results demonstrated that the pathological stage was exacerbated with the increase in time of 4NQO-mediated carcinogenesis induction, and the pathological features were similar to those observed in humans. Immunohistochemistry results revealed that B7-H4 expression was upregulated and positively correlated with pathological stage (P<0.0001) as well as with infiltration of cluster of differentiation (CD) 11b⁺ macrophage cells (P=0.0002). In addition, B7-H4 messenger RNA expression increased in the esophagi of model mice compared with that of control mice, which was positively associated with the gene expression of interleukin (IL)-6 and signal transducer and activator of transcription 3 (STAT3), according to the results of reverse transcription-quantitative polymerase chain reaction analysis. Similarly, B7-H4 protein expression was upregulated in the esophageal tissues of model mice in comparison with that of control mice, and was positively associated with IL-6 expression and STAT3 phosphorylation. In conclusion, the present data suggested that B7-H4 expression increased during esophageal squamous cell carcinogenesis in mice in association with IL-6/STAT3 signaling pathway activation.

B7-H4 is Predictive of Poor Prognosis in Patients with Gastric Cancer

Background

Recently, some studies were performed to evaluate the relevance of B7-H4 and gastric cancer (GC) prognosis. However, the results remained controversial. Therefore, we performed the present meta-analysis.

Material/Methods

We performed a systematic search in PubMed and Web of Science databases. All data were extracted and reviewed from each eligible study independently by 2 investigators. The strength of association between B7-H4 and GC prognosis was assessed by computing odds ratio (OR) with its corresponding 95% confidence interval (CI).

Results

Six studies that evaluated the association between B7-H4 and GC prognosis were included. The results showed a statistically significant association of B7-H4 and GC prognosis (OR=1.63, 95%CI=1.30–2.03). Furthermore, we conducted subgroup analysis based on source of B7-H4; the results from blood (OR=1.71; 95%CI, 1.09–2.68) and tissue (OR=1.60; 95%CI, 1.03–2.07) indicated B7-H4 was significantly associated with poor prognosis.

Conclusions

This meta-analysis suggests that GC patients with high B7-H4 have poor prognosis.

Aberrant expression of B7‑H4 may contribute to the development of hepatocellular carcinoma

In order to determine the effect of B7‑H4 on the development of human hepatocellular carcinoma (HCC), the expression levels of B7‑H4 were evaluated using reverse transcription‑polymerase chain reaction and flow cytometry in HL‑7702 and Huh7 cells. B7‑H4 protein expression levels were analyzed using western blotting and immunohistochemistry in HCC tissues collected from patients and from a mouse tumor model. Soluble B7‑H4 (sB7‑H4), interferon‑γ (IFN‑γ), and interleukin‑4 (IL‑4) in blood serum were assessed using ELISA in patients with HCC and mice injected with tumor cells. B7‑H4 was expressed in HCC cell lines, mouse tumor tissues and HCC patient tissues. However, B7‑H4 was not detected in HL‑7702 cells or normal human liver tissues. The expression level of B7‑H4 was positively correlated with tumor‑node‑metastasis (TNM) stage, lymph node metastasis, and differentiation degree in patients with HCC. sB7‑H4 levels in blood serum samples collected from patients with HCC and tumorigenic mice were higher compared with healthy controls. Expression levels of IFN‑γ were reduced, and IL‑4 levels were increased in blood serum samples of patients with HCC and tumorigenic mice compared with healthy controls. sB7‑H4 expression levels were negatively correlated with IFN‑γ levels, and with the ratio of IFN‑γ to IL‑4. Additionally, sB7‑H4 was positively correlated with IL‑4 levels in mouse tumor tissues, serum samples obtained from tumorigenic mice and human HCC patients. Notably, the levels of sB7‑H4 and IL‑4 were positively correlated and IFN‑γ was negatively correlated with the TNM stage of patients with HCC. In addition, sB7‑H4 and IL‑4 expression levels increased and levels of IFN‑γ and the ratio of IFN‑γ/IL‑4 decreased as a function of time post tumor implantation in the mouse model. The present study determined that aberrant expression of B7‑H4 contributed to HCC development. B7‑H4 may be a potential target for therapy and diagnosis of HCC.

B7-H4 facilitates proliferation of esophageal squamous cell carcinoma cells through promoting interleukin-6/signal transducer and activator of transcription 3 pathway activation

B7‐H4, one of the costimulatory molecules of the B7 family, has been found to be widely expressed in many kinds of tumor tissues and to play an important part in tumor progression and poor prognosis. However, the role of B7‐H4 in esophageal squamous cell carcinoma (ESCC) cells has not been elucidated. In this study, we found that, compared with normal esophageal tissue, B7‐H4 was highly expressed in three ESCC cell lines, Eca109, TE1, and TE13. B7‐H4 silenced cells suppressed cellular proliferation and colony formation. Additionally, compared with control cells, B7‐H4 silenced cells showed higher apoptosis rates, Bcl‐2 and Survivin upregulation, and BAX downregulation. Further study revealed that B7‐H4 silenced cells also showed reduction in interleukin‐6 (IL‐6) secretion, signal transducer and activator of transcription 3 (STAT3) activation, and p‐STAT3 translocation from cytoplasm to nucleus. Moreover, B7‐H4 depletion inhibited the IL‐6 secretion of control cells but not JAK2/STAT3 inhibitor FLLL32‐treated cells. Interleukin‐6 receptor antagonist tocilizumab did not block the p‐JAK2 or p‐STAT3 downregulation induced by B7‐H4 silence. It was suggested that B7‐H4 silence suppressed IL‐6 secretion through JAK2/STAT3 inactivation. Furthermore, cell proliferation and colony formation were downregulated by tocilizumab in control cells but not in B7‐H4 silenced cells, indicating that IL‐6 upregulation induced by B7‐H4 was necessary for cell growth. On the other hand, B7‐H4 expression was downregulated by tocilizumab. In all, our study provided the first evidence that B7‐H4 facilitated ESCC cell proliferation through promoting IL‐6/STAT3 positive loopback pathway activation.

B7-H4 downregulation induces mitochondrial dysfunction and enhances doxorubicin sensitivity via the cAMP/CREB/PGC1-α signaling pathway in HeLa cells

B7-H4 is a B7 family coregulatory protein that inhibits T cell-mediated immunity. B7-H4 is overexpressed in various cancers; however, the functional role of B7-H4 in cancer metabolism is poorly understood. Because mitochondria play pivotal roles in development, proliferation, and death of cancer cells, we investigated molecular and functional alterations of mitochondria in B7-H4-depleted HeLa cells. In a human study, overexpression of B7-H4 was confirmed in the cervices of adenocarcinoma patients (n = 3) compared to noncancer patients (n = 3). In the cell line model, B7-H4 depletion was performed by transfection with small interfering RNA (siRNA). B7-H4 depletion suppressed oxygen consumption rate, ATP production, and mitochondrial membrane potential and mass and increased reactive oxygen species production. In particular, electron transport complex III activity was significantly impaired in siB7-H4-treated cells. Coincidently, depletion of B7-H4 suppressed major mitochondrial regulators (peroxisome proliferator-activated receptor gamma coactivator 1-alpha [PGC1-α] and mitochondrial transcription factor A), a component of oxidative phosphorylation (ubiquinol-cytochrome c reductase core protein 1), and an antiapoptosis protein (Bcl-XL). Mitochondrial dysfunction in siRNA-treated cells significantly augmented oxidative stress, which strongly activated the JNK/P38/caspase axis in the presence of doxorubicin, resulting in increased apoptotic cell death. Investigating the mechanism of B7-H4-mediated mitochondrial modulation, we found that B7-H4 depletion significantly downregulated the cAMP/cAMP response element-binding protein/PGC1-α signaling pathway. Based on these findings, we conclude that B7-H4 has a role in the regulation of mitochondrial function, which is closely related to cancer cell physiology and drug sensitivity.

Combination cancer immunotherapy and new immunomodulatory targets

Targeting immune checkpoints such as programmed cell death protein 1 (PD1), programmed cell death 1 ligand 1 (PDL1) and cytotoxic T lymphocyte antigen 4 (CTLA4) has achieved noteworthy benefit in multiple cancers by blocking immunoinhibitory signals and enabling patients to produce an effective antitumour response. Inhibitors of CTLA4, PD1 or PDL1 administered as single agents have resulted in durable tumour regression in some patients, and combinations of PD1 and CTLA4 inhibitors may enhance antitumour benefit. Numerous additional immunomodulatory pathways as well as inhibitory factors expressed or secreted by myeloid and stromal cells in the tumour microenvironment are potential targets for synergizing with immune checkpoint blockade. Given the breadth of potential targets in the immune system, critical questions to address include which combinations should move forward in development and which patients will benefit from these treatments. This Review discusses the leading drug targets that are expressed on tumour cells and in the tumour microenvironment that allow enhancement of the antitumour immune response.

B7-H4 expression is associated with tumor progression and prognosis in patients with osteosarcoma

Increasing evidences have demonstrated that B7-H4 is associated with tumor development and prognosis. However, the clinical significance of B7-H4 expression in human osteosarcoma (OS) remains unclear. The aim of present study was to examine the B7-H4 expression and to explore its contribution in OS. B7-H4 expression in OS tissues was examined by immunohistochemistry. Soluble B7-H4 (sB7-H4) levels in blood were examined by ELISA. The association of B7-H4 expression with clinicopathological factors or prognosis was statistically analyzed. Our findings demonstrated that B7-H4 expression in OS tissues was significantly higher than those in paired normal bone tissues (P < 0.001). sB7-H4 level in OS serum samples was significantly higher than that in healthy controls (P = 0.005). High B7-H4 expression in tissues and sB7-H4 level were both correlated with advanced tumor stage (P < 0.001, P = 0.017, resp.) and distant metastasis (P = 0.034, P = 0.021, resp.). Additionally, high B7-H4 expression or serum sB7-H4 levels were significantly related to poor overall survival (P = 0.028, P = 0.005, resp.). B7-H4 in tissues and serum samples were an independent factor for affecting the survival time of OS patients (P = 0.004, P = 0.041, resp.). Collectively, our data suggest that the evaluation of B7-H4 expression in tissues and blood is a useful tool for predicting the progression of osteosarcoma and prognosis.

Clinical Significance of Circulating Tumor Cells in Peripheral Blood of Patients with Esophageal Squamous Cell Carcinoma

BACKGROUND

Esophageal squamous cell carcinoma is an aggressive gastrointestinal tract cancer. To date, the presence of circulating tumor cells (CTC) has been reported as a prognostic factor in peripheral blood from patients with gastrointestinal cancers.

METHODS

The CellSearch system was used to isolate and enumerate CTCs. A total of 90 patients with esophageal squamous cell carcinoma who received chemotherapy or chemoradiotherapy were enrolled. Peripheral blood specimens were collected before and after treatments.

RESULTS

At baseline analysis, CTCs were detected in 25 patients (27.8 %). Overall survival was significantly shorter in patients with than without CTCs. Follow-up blood specimens were obtained from 71 patients. Partial response, stable disease, and progressive disease after treatment were seen in 32, 12, and 27 patients, respectively. CTC positivity after treatment in the progressive disease group (40.7 %) was significantly higher than that of the partial response group (6.3 %). Patients with a change in CTC status from positive to negative had a good prognosis as well as patients without baseline CTCs.

CONCLUSIONS

Evaluation of CTCs may be a promising indicator for predicting tumor prognosis and the clinical efficacy of chemotherapy or chemoradiation therapy in patients with esophageal squamous cell carcinoma.

B7-H abnormalities in melanoma and clinical relevance

Melanoma have been shown to escape immune surveillance by different mechanisms such as loss of HLA class I antigens, upregulation of nonclassical HLA-G antigen and Fas, increased secretion of immune suppressive cytokines and metabolites as well as altered expression of co-stimulatory and coinhibitory signals. Recently, an important role of B7-H1 and B7-H4 in the immune escape of melanoma has been described. High mRNA and/or protein expression levels of these coinhibitory molecules were detected in both melanoma cell lines and melanoma lesions when compared to melanocytes. However, their clinical relevance is currently controversially discussed regarding a correlation of B7-H family members with tumor grading and staging as well as survival of patients in melanoma.

B7-H4 overexpression correlates with a poor prognosis for cervical cancer patients

Cervical cancer is a major global public health care concern and the second most commonly diagnosed malignancy among females worldwide. B7-H4 is an immunoregulatory protein that has been shown to be overexpressed in several types of cancer and is often associated with more advanced disease and poor prognosis. We investigated whether B7-H4 is a prognostic maker for cervical cancer by detecting its expression in cervical cancer specimens. Formalin-fixed, paraffin-embedded tissue blocks from cervical cancer were evaluated for B7-H4 expression by immunohistochemistry with free R software analysis. The intensity of B7-H4 immunoexpression was evaluated according to age, histological type, International Federation of Gynecology and Obstetrics (FIGO) stage, lymphovascular space invasion (LVSI) and lymph node status. We investigated the distribution and expression of B7-H4 in 102 cervical cancer specimens and determined the association between its expression and clinicopathological characteristics, including patient outcomes. Of the 102 specimens, 31 were found to be negative for B7-H4 immunoexpression, whereas 71 were B7-H4-positive. When classified by negative vs. positive expression, B7-H4 was not found to be associated with any of the clinicopathological parameters investigated. A positive B7-H4 expression significantly predicted poor overall survival (OS) when compared to negative expression (P<0.05). In the multivariate analysis, positive B7-H4 expression was identified as an independent prognostic factor for OS (P<0.05). Our data suggested that positive B7-H4 expression may be a useful biomarker in patients with cervical cancer likely to have an unfavorable clinical outcome.

B7-H6 protein expression has no prognostic significance in human gastric carcinoma

B7-H6, a novel member of the B7 family which binds to NKp30 to trigger antitumor NK cell cytotoxicity and cytokine secretion. Recently, B7-H family has been reported to be a negative regulator of the immune response in patients with gastric carcinoma. However, no reports have investigated the clinical significance of B7-H6 expression in human gastric cancer. We present the first study to the clinicopathological and prognostic value of B7-H6 in primary gastric tumors and adjacent non-tumor tissues at the protein level. Here we show that B7-H6 immunoreactivity was expressed in 6/60 (10%) gastric tumors and 8/43 (18.60%) adjacent non-tumor tissues. No statistical difference was found between B7-H6 expression and various prognostic factors; however, B7-H6-positive carcinomas were significantly associated with a higher differentiation (p = 0.047). The survival analysis did not confirm the prognostic significance of B7-H6 expression in gastric cancer patients. Our data suggest that B7-H6, as detected by immunohistochemistry, is of limited value as a prognostic marker for gastric cancer.

B7 family checkpoint regulators in immune regulation and disease

Fine-tuning the immune response and maintaining tolerance to self-antigens involves a complex network of co-stimulatory and co-inhibitory molecules. The recent FDA approval of ipilimumab, a monoclonal antibody blocking cytotoxic T lymphocyte antigen (CTLA)-4, demonstrates the impact of checkpoint regulators in disease. This is reinforced by ongoing clinical trials targeting not only CTLA-4, but also the programmed death (PD)-1 and B7-H4 pathways in various disease states. Recently, two new B7 family inhibitory ligands, V-domain Ig suppressor of T cell activation (VISTA) and B7-H6 were identified. Here, we review recent understanding of B7 family members and their concerted regulation of the immune response to either self or foreign pathogens. We also discuss clinical developments in targeting these pathways in different disease settings, and introduce VISTA as a putative therapeutic target.

Clinical significance of circulating tumor cells in peripheral blood from patients with gastric cancer

BACKGROUND

The authors hypothesized that circulating tumor cells (CTCs) in patients with gastric cancer are associated with prognosis and disease recurrence. In this study, they evaluated CTCs in gastric cancer and clarified the clinical impact of CTCs.

METHODS

In total, 265 consecutive patients with gastric cancer were enrolled. Fourteen patients were excluded from the analysis, including 12 patients who another cancer and 2 patients who refused the treatment. The remaining 251 patients were divided into 2 groups: 148 patients who underwent gastrectomy (the resection group) and 103 patients who did not undergo gastrectomy (the nonresectable group). Peripheral blood samples were collected before gastrectomy or chemotherapy. A proprietary test for capturing, identifying, and counting CTCs in blood was used for the isolation and enumeration of CTCs.

RESULTS

CTCs were detected in 16 patients (10.8%) from the resection group and in 62 patients (60.2%) from the nonresectable group. The overall survival rate for the entire cohort was significantly lower in patients with CTCs than in those without CTCs (P < .0001). In the resection group, relapse-free and overall survival in patients with CTCs was significantly lower than in patients without CTCs (P < .0001). It was noteworthy that the expression of CTCs was an independent factor for determining the overall survival of patients with gastric cancer in multivariate analysis (P = .024). In the nonresectable group, the overall survival rate was significantly lower in patients with CTCs than in those without CTCs (P = .0044).

CONCLUSIONS

The evaluation of CTCs in peripheral blood may be a useful tool for predicting tumor progression, prognosis, and the effect of chemotherapy in patients with gastric cancer.

Host b7x promotes pulmonary metastasis of breast cancer

B7x (B7-H4 or B7S1) is an inhibitory member of the B7 family of T cell costimulation. It is expressed in low levels in healthy peripheral tissues, such as the lung epithelium, but is overexpressed in a variety of human cancers with negative clinical associations, including metastasis. However, the function of B7x in the context of cancer, whether expressed on cancer cells or on surrounding "host" tissues, has not been elucidated in vivo. We used the 4T1 metastatic breast cancer model and B7x knockout (B7x (-/-)) mice to investigate the effect of host tissue-expressed B7x on cancer. We found that 4T1 cells were B7x negative in vitro and in vivo, and B7x(-/-) mice had significantly fewer lung 4T1 tumor nodules than did wild-type mice. Furthermore, B7x(-/-) mice showed significantly enhanced survival and a memory response to tumor rechallenge. Mechanistic studies revealed that the presence of B7x correlated with reduced general and tumor-specific T cell cytokine responses, as well as with an increased infiltration of immunosuppressive cells, including tumor-associated neutrophils, macrophages, and regulatory T cells, into tumor-bearing lungs. Importantly, tumor-associated neutrophils strongly bound B7x protein and inhibited the proliferation of both CD4 and CD8 T cells. These results suggest that host B7x may enable metastasizing cancer cells to escape local antitumor immune responses through interactions with the innate and adaptive immune systems. Thus, targeting the B7x pathway holds much promise for improving the efficacy of immunotherapy for metastatic cancer.

The costimulatory molecule B7-H4 promote tumor progression and cell proliferation through translocating into nucleus

B7-H4, a member of B7 family, is a transmembrane protein and inhibits T-cells immunity. However, in a variety of tumor cells, B7-H4 was detected predominantly in intracellular compartments with unknown mechanism and functions. In this study, we analyzed B7-H4 expression and subcellular distribution by immunohistochemistry in renal cell carcinoma (RCC) tissues. B7-H4 protein was detected on the membrane, in the cytosol and/or in the nucleus in tumor tissues. The membrane and nuclear expression of B7-H4 was significantly correlated with the tumor stages of RCC. Moreover, the membrane localization of B7-H4 was inversely correlated with the intensity of tumor infiltrates lymphocyte (TILs), whereas no association was observed between nuclear expression of B7-H4 and the density of TILs status. We further identified that B7-H4 is a cytoplasmic-nuclear shuttling protein containing a functional nuclear localization sequence (NLS) motif. A point mutation of B7-H4 NLS motif blocked the leptomycin B -induced nuclear accumulation of B7-H4. HEK293 cells stably expressing B7-H4 NLS mutant exhibited more potent inhibition in T-cell proliferation and cytokine production through increasing its surface expression compared with wild-type B7-H4 transfected cells owing to their increased surface expression. Most importantly, overexpression of wild-type B7-H4 in HEK293 cells enhanced tumor cell proliferation in vitro and tumorigenicity in vivo, promoted G1/S phase transition. The regulation of cell cycle by wild-type B7-H4 was partialy due to upregulation of Cyclin D 1 and Cyclin E. A mutation of B7-H4 NLS motif abolished the B7-H4-mediated cell proliferation and cell cycle regulation. Furthermore, B7-H4 wild-type confers chemoresistance activity to RCC cell lines including Caki-1 and ACHN. Our study provides a new insight into the functional implication of B7-H4 in its subcellular localization.