Expression of the B7-related molecule ICOSL by human glioma cells in vitro and in vivo

An integrated pan-cancer assessment of prognosis, immune infiltration, and immunotherapy response for B7 family using multi-omics data

AIMS

B7 molecules (B7s) are crucial synergistic signals for effective immune surveillance against tumor cells. While previous studies have explored the association between the B7 family and cancer, most have been limited to specific genes or cancer subtypes.

MAIN METHODS

Our study utilized multi-omics data to investigate potential correlations between B7s expression (B7s exp.) and prognosis, clinicopathological features, somatic mutations (SMs), copy number variations (CNVs), immune characteristics, tumor microenvironment (TME), microsatellite instability, tumor mutation burden, immune checkpoint gene (ICG), and drug responsiveness in TCGA tumors. Furthermore, the connection between B7s exp. and immunotherapy (IT) performance assessed in various validated datasets. Following this, immune infiltration analysis (IIA) was conducted based on B7s exp., CNVs, or SMs in bladder cancer (BLCA), complemented by real-time PCR (RT-PCR) and protein confirmation of B7-H3.

KEY FINDINGS

Across most cancer types, B7s exp. was related to prognosis, clinicopathological characteristics, mutations, CNVs, ICG, TMB, TME. The examination of sensitivity to anticancer drugs unveiled correlations between B7 molecules and different drug sensitivities. Specific B7s exp. patterns were linked to the clinical effectiveness of IT. Using GSEA, several enriched immune-related functions and pathways were identified. Particularly in BLCA, IIA revealed significant connections between B7 CNVs, mutation status, and various immune cell infiltrates. RT-PCR confirmed elevated B7-H3 gene levels in BLCA tumor tissues.

SIGNIFICANCE

This study confirmed the significance of B7s exp. and genomic changes in predicting outcomes and treatment across different cancer types. Moreover, they indicate a critical function of B7s in BLCA and their potential as IT biomarkers.

From glioma gloom to immune bloom: unveiling novel immunotherapeutic paradigms-a review

In tumor therapeutics, the transition from conventional cytotoxic drugs to targeted molecular therapies, such as those targeting receptor tyrosine kinases, has been pivotal. Despite this progress, the clinical outcomes have remained modest, with glioblastoma patients' median survival stagnating at less than 15 months. This underscores the urgent need for more specialized treatment strategies. Our review delves into the progression toward immunomodulation in glioma treatment. We dissect critical discoveries in immunotherapy, such as spotlighting the instrumental role of tumor-associated macrophages, which account for approximately half of the immune cells in the glioma microenvironment, and myeloid-derived suppressor cells. The complex interplay between tumor cells and the immune microenvironment has been explored, revealing novel therapeutic targets. The uniqueness of our review is its exhaustive approach, synthesizing current research to elucidate the intricate roles of various molecules and receptors within the glioma microenvironment. This comprehensive synthesis not only maps the current landscape but also provides a blueprint for refining immunotherapy for glioma, signifying a paradigm shift toward leveraging immune mechanisms for improved patient prognosis.

ICOSLG acts as an oncogene to promote glycolysis, proliferation, migration, and invasion in gastric cancer cells

Gastric cancer (GC) has emerged as one of the most common malignancies in gastrointestinal system. Inducible T-cell costimulator ligand (ICOSLG) was found to be highly expressed in various cancers, which contributes to disease progression. This study aims to investigate the role of ICOSLG and its potential mechanism of action in dictating the aggressiveness of GC cell. ICOSLG and miR-331-3p expression patterns in cancerous and para-cancerous tissues from GC patients were examined by quantitative reverse transcription-polymerase chain reaction (qRT-PCR). The miRNAs targeting ICOSLG were predicted by "miRDB", "starBase," and "TargetScan" databases. The interplay of ICOSLG and miR-331-3p in dictating the aggressiveness and glycolysis of GC cells was investigated by CCK-8 proliferation assay and Transwell migration/invasion assays, as well as the detection of glucose uptake, lactate production and ATP levels. The tumorigenesis of GC cells after ICOSLG silencing was examined in the nude mice. ICOSLG was highly expressed in GC tissues, and GC patients with high ICOSLG expression showed a poorer prognosis than the low-expression group. Further, high ICOSLG level was correlated with more advanced TNM stages, more lymph-node metastases, and poorer tumor differentiation. ICOSLG knockdown inhibited the proliferation, migration, invasion and tumor formation of GC cells, which was concomitant with reduced glucose consumption, lactate production, and ATP levels. In contrast, ICOSLG overexpression enhanced the aggressiveness of GC cells, and this effect was abrogated after the treatment with glycolysis inhibitor. We further found that miR-331-3p was a negative regulator of ICOSLG4, and miR-331-3p overexpression reduced ICOSLG4 expression and suppressed the aggressive phenotype induced by ICOSLG4 in GC cells. Together, these findings indicate that ICOSLG4, as an oncogene, is upregulated to promote glycolysis and the malignant phenotype in GC cells. miR-331-3p, which is downregulated in GC tissues, functions as a negative regulator of ICOSLG4. Targeting miR-331-3p/ICOSLG4 axis could potentially suppress GC progression.

Normofractionated irradiation and not temozolomide modulates the immunogenic and oncogenic phenotype of human glioblastoma cell lines

PURPOSE

Glioblastoma multiforme (GBM) is the most aggressive primary brain tumor, with an overall poor prognosis after diagnosis. Conventional treatment includes resection, chemotherapy with temozolomide (TMZ), and concomitant radiotherapy (RT). The recent success of immunotherapy approaches in other tumor entities, particularly with immune checkpoint inhibitors, could not be clinically transferred to GBM treatment so far. Therefore, preclinical analyses of the expression of both immune-suppressive and immune-stimulatory checkpoint molecules following treatment of human glioblastoma cells with RT and/or temozolomide is needed to design feasible radio(chemo)immunotherapy trials for GBM in the future.

METHODS

Five human glioblastoma cell lines (H4, HROG-06, U118, U138, U251) were analyzed regarding their clonogenic survival and cell death forms after chemotherapy (CT) with TMZ and/or normofractionated RT (5 × 2 Gy) via multicolor flow cytometry. Further, the tumor cell surface expression of immune-activating (OX40L, CD137L, CD70, and ICOSL) and immune-suppressive (PD-L1, PD-L2, HVEM) checkpoint molecules and of an oncogenic molecule (EGFR) were measured via multicolor flow cytometry after CT and RT alone or after RCT.

RESULTS

Normofractionated RT and not TMZ was the trigger of induction of predominantly necrosis in the glioblastoma cells. Notably, clonogenicity did not correlate with cell death induction by RT. The basal expression level of immune-suppressive PD-L1, PD-L2, and HVEM varied in the analyzed glioblastoma cells. RT, but not TMZ, resulted in a significant upregulation of PD-L1 and PD-L2 in all tumor cells investigated. Also, the expression of HVEM was increased after RT in most of the GBM cell lines. In contrast, normofractionated RT individually modulated expression of the stimulating immune checkpoint molecules CD70, CD137L, OX40L, and ICOSL1. The oncogenic factor EGFR was significantly increased by irradiation in all examined cell lines, albeit to a different extent. None of the investigated molecules were downregulated after the treatments.

CONCLUSION

Normofractionated radiotherapy modulates the immunogenic as well as the oncogenic phenotype of glioblastoma cells, partly individually. Therefore, not only PD-L1 and PD-L2, but also other immunogenic molecules expressed on the surface of glioblastoma cells could serve as targets for immune checkpoint blockade in combination with RT in the future.

ICOSLG-associated immunological landscape and diagnostic value in oral squamous cell carcinoma: a prospective cohort study

Background: We previously reported that stroma cells regulate constitutive and inductive PD-L1 (B7-H1) expression and immune escape of oral squamous cell carcinoma. ICOSLG (B7-H2), belongs to the B7 protein family, also participates in regulating T cells activation for tissue homeostasis via binding to ICOS and inducing ICOS+ T cell differentiation as well as stimulate B-cell activation, while it appears to be abnormally expressed during carcinogenesis. Clarifying its heterogeneous clinical expression pattern and its immune landscape is a prerequisite for the maximum response rate of ICOSLG-based immunotherapy in a specific population. Methods: This retrospective study included OSCC tissue samples (n = 105) to analyze the spatial distribution of ICOSLG. Preoperative peripheral blood samples (n = 104) and independent tissue samples (n = 10) of OSCC were collected to analyze the changes of immunocytes (T cells, B cells, NK cells and macrophages) according to ICOSLG level in different cellular contents. Results: ICOSLG is ubiquitous in tumor cells (TCs), cancer-associated fibroblasts (CAFs) and tumor infiltrating lymphocytes (TILs). Patients with high ICOSLGTCs or TILs showed high TNM stage and lymph node metastasis, which predicted a decreased overall or metastasis-free survival. This sub-cohort was featured with diminished CD4+ T cells and increased Foxp3+ cells in invasive Frontier in situ, and increased absolute numbers of CD3+CD4+ and CD8+ T cells in peripheral blood. ICOSLG also positively correlated with other immune checkpoint molecules (PD-L1, CSF1R, CTLA4, IDO1, IL10, PD1). Conclusion: Tumor cell-derived ICOSLG could be an efficient marker of OSCC patient stratification for precision immunotherapy.

Identification of a single cell-based signature for predicting prognosis risk and immunotherapy response in patients with glioblastoma

This study constructed a novel gene pair signature based on bulk and single-cell sequencing samples in relative expression order within the samples. The subsequent analysis included glioma samples from Xiangya Hospital. Gene pair signatures possessed a solid ability to predict the prognosis of glioblastoma and pan-cancer. Samples having different malignant biological hallmarks were distinguished by the algorithm, with the high gene pair score group featuring classic copy number variations, oncogenic mutations, and extensive hypomethylation, mediating poor prognosis. The increased gene pair score group with a poorer prognosis demonstrated significant enrichment in tumor and immune-related signaling pathways while presenting immunological diversity. The remarkable infiltration of M2 macrophages in the high gene pair score group was validated by multiplex immunofluorescence, suggesting that combination therapies targeting adaptive and innate immunity may serve as a therapeutic option. Overall, a gene pair signature applicable to predict prognosis hopefully provides a reference to guide clinical practice.

Role of CD4+CD25+FOXP3+ TReg cells on tumor immunity

Not all T cells are effector cells of the anti-tumor immune system. One of the subpopulations of CD4⁺ T cells that express CD25⁺ and the transcription factor FOXP3, known as Regulator T cells (T_Reg), plays an essential role in maintaining tolerance and immune homeostasis preventing autoimmune diseases, minimalize chronic inflammatory diseases by enlisting various immunoregulatory mechanisms. The balance between effector T cells (T_eff) and regulator T cells is crucial in determining the outcome of an immune response. Regarding tumors, activation or expansion of T_Reg cells reduces anti-tumor immunity. T_Reg cells inhibit the activation of CD4⁺ and CD8⁺ T cells and suppress anti-tumor activity in the tumor microenvironment. In addition, T_Reg cells also promote tumor angiogenesis both directly and indirectly to ensure oxygen and nutrient transport to the tumor. There is accumulating evidence showing a positive result that removing or suppressing T_Reg cells increases anti-tumor immune response. However, depletion of T_Reg cells will cause autoimmunity. One strategy to improve or restore tumor immunity is targeted therapy on the dominant effector T_Reg cells in tumor tissue. Various molecules such as CTLA-4, CD4, CD25, GITR, PD-1, OX40, ICOS are in clinical trials to assess their role in attenuating T_Reg cells' function.

T lymphocyte-targeted immune checkpoint modulation in glioma

Immunomodulatory therapies targeting inhibitory checkpoint molecules have revolutionized the treatment of solid tumor malignancies. Concerns about whether systemic administration of an immune checkpoint inhibitor could impact primary brain tumors were answered with the observation of definitive responses in pediatric patients harboring hypermutated gliomas. Although initial clinical results in patients with glioblastoma (GBM) were disappointing, recently published results have demonstrated a potential survival benefit in patients with recurrent GBM treated with neoadjuvant programmed cell death protein 1 blockade. While these findings necessitate verification in subsequent studies, they support the possibility of achieving clinical meaningful immune responses in malignant primary brain tumors including GBM, a disease in dire need of additional therapeutic options. There are several challenges involved in treating glioma with immune checkpoint modulators including the immunosuppressive nature of GBM itself with high inhibitory checkpoint expression, the immunoselective blood brain barrier impairing the ability for peripheral lymphocytes to traffic to the tumor microenvironment and the high prevalence of corticosteroid use which suppress lymphocyte activation. However, by simultaneously targeting multiple costimulatory and inhibitory pathways, it may be possible to achieve an effective antitumoral immune response. To this end, there are now several novel agents targeting more recently uncovered “second generation” checkpoint molecules. Given the multiplicity of drugs being considered for combination regimens, an increased understanding of the mechanisms of action and resistance combined with more robust preclinical and early clinical testing will be needed to be able to adequately test these agents. This review summarizes our current understanding of T lymphocyte-modulating checkpoint molecules as it pertains to glioma with the hope for a renewed focus on the most promising therapeutic strategies.

Plasma IL-8 and ICOSLG as prognostic biomarkers in glioblastoma

Background

CNS immune privilege has been challenged in recent years. Glioblastoma (GBM) immune dysfunction includes complex interactions with the immune system outside the CNS. The aim of this study was to determine diagnostic and prognostic potential of immune-related proteins in plasma in GBM and interrogate biomarker presence in the brain tumor microenvironment (TME).

Methods

One hundred and fifty-eight patients with glioma WHO grade II–IV were included. Plasma collected at surgery was screened for 92 proteins using proximity extension assay technology and related to clinical outcome. Secretion and expression of candidate prognostic biomarkers were subsequently analyzed in 8 GBM cell lines and public RNAseq data.

Results

Plasma levels of 20 out of 92 screened proteins were significantly different in patients with GBM compared to patients with astrocytoma WHO grade II–III. High plasma interleukin-8 (IL-8) (hazard ratio [HR] = 1.52; P = .0077) and low CD244 (HR = 0.36; P = .0004) were associated with short progression-free survival and high plasma IL-8 (HR = 1.40; P = .044) and low ICOS ligand (ICOSLG) (HR = 0.17; P = .0003) were associated with short overall survival (OS) in newly diagnosed patients with GBM. A similar trend was found for ICOSLG (HR = 0.34; P = .053) in recurrent GBM. IL-8 was mostly secreted and expressed by mesenchymal GBM cell lines and expressed by vascular cells and immune cells in the TME. This was also the case for ICOSLG, although less consistent, and with additional expression in tumor-associated oligodendrocytes.

Conclusions

High plasma IL-8 and low ICOSLG at surgery are associated with short OS in newly diagnosed GBM. Source of plasma ICOSLG may be found outside the TME.

Genomic Analysis of Glioblastoma Multiforme Reveals a Key Transcription Factor Signature Relevant to Prognosis and the Immune Processes

Introduction

Glioblastoma multiforme (GBM) develops through the accumulation of both genetic and expression alterations. Although many gene signatures have been developed as prognostic and predictive biomarkers, their robustness and functional aspects are less well characterized. The expression of most genes is regulated by transcription factors (TFs); therefore, we aimed to investigate a TF signature relevant to GBM prognosis.

Methods

We used bioinformatic methods and data from public databases to establish four clusters of key TF genes, among which cluster 1, comprising 24 TFs, showed significant prognostic value. Further in silico functional analyses were applied to investigate the utility of the TF signature.

Results

Different mutation and copy number variation patterns were observed between different risk score groups (based on the TF signature). In silico analyses suggested that the cases with relative high risk scores were involved in immune and inflammatory processes or pathways.

Conclusion

The TF signature has significant prognostic value in different cohorts or subgroups of patients with GBM and could lead to the development immunotherapy for GBM.

ICOSLG-mediated regulatory T-cell expansion and IL-10 production promote progression of glioblastoma

BACKGROUND

Targeting immune checkpoint proteins has recently gained substantial attention due to the dramatic success of this strategy in clinical trials for some cancers. Inducible T-cell co-stimulator ligand (ICOSLG) is a member of the B7 family of immune regulatory ligands, expression of which in cancer is implicated in disease progression due to regulation of antitumor adaptive immunity. Although aberrant ICOSLG expression has been reported in glioma cells, the underlying mechanisms that promote glioblastoma (GBM) progression remain elusive.

METHODS

Here, we investigated a causal role for ICOSLG in GBM progression by analyzing ICOSLG expression in both human glioma tissues and patient-derived GBM sphere cells (GSCs). We further examined its immune modulatory effects and the underlying molecular mechanisms.

RESULTS

Bioinformatics analysis and GBM tissue microarray showed that upregulation of ICOSLG expression was associated with poor prognosis in patients with GBM. ICOSLG expression was upregulated preferentially in mesenchymal GSCs but not in proneural GSCs in a tumor necrosis factor-α/nuclear factor-kappaB-dependent manner. Furthermore, ICOSLG expression by mesenchymal GSCs promoted expansion of T cells that produced interleukin-10. Knockdown of the gene encoding ICOSLG markedly reduced GBM tumor growth in immune competent mice, with a concomitant downregulation of interleukin-10 levels in the tumor microenvironment.

CONCLUSIONS

Inhibition of the ICOSLG-inducible co-stimulator axis in GBM may provide a promising immunotherapeutic approach for suppressing a subset of GBM with an elevated mesenchymal signature.

Role of Inducible Co-Stimulator (ICOS) in cancer immunotherapy

Introduction: The promotion of antitumor response by targeting co-stimulatory B7 superfamily members has become evident to create a new wave of cancer immunotherapy. Inducible Co-Stimulator (ICOS), which is expressed on activated T cells, gained interest in the translational medicine community.Areas covered: We performed an extensive literature review using the keywords 'ICOS' and 'cancer', and the Clinicaltrials.gov database for early phase clinical trials targeting ICOS. In this review, we highlight the dual role of ICOS in oncogenesis in different malignancies. We summarize the current state of knowledge about ICOS/ICOSL pathway targeting by immunotherapies.Expert opinion: Due to its multifaceted link with anti-tumor immunity, both antagonist and agonist antibodies might be of interest to target the ICOS/ICOSL pathway for tumor treatment. Indeed, ICOS activation might potentiate the effect of an inhibitory checkpoint blockade, while its neutralization could decrease the function of immunosuppressive Tregs and inhibit lymphoid tumor cells expressing Tfh markers.

Expression of ICOSL is associated with decreased survival in invasive breast cancer

Background

Inducible co-stimulator (ICOS) is a CD28-related molecule exclusively expressed on activated T cells and plays a critical role in modulating the immune response in breast cancer. The blockage of ICOS pathway has been shown to inhibit the activity of Type 2 T helper cells, thus potentially protecting against cancer growth. The current study aims to investigate the correlation between inducible co-stimulator ligand (ICOSL) expression in tumor tissues and the prognoses of patients with invasive breast cancer.

Methods

Tumor samples from 562 Chinese patients with invasive breast carcinomas were collected between 2003 and 2010. The expression of ICOSL on breast tumor and adjacent non-cancerous tissue was determined via immunohistochemistry. The overall survival (OS) of patients with positive and negative ICOSL expression were described using Kaplan–Meier curves, respectively. Parametric correlation method was used to analyze the correlation between ICOSL expression and other clinicopathological parameters. ICOSL was selected as a dependent variable for multivariate analysis.

Results

Positive ICOSL expression was identified on the plasma membrane in both cytoplasm and the nucleus of breast cancer cells. Membrane-expressed ICOSL is determined as an independent prognostic factor for OS in breast cancer but without significantly correlating with other clinicopathologic parameters such as age, menopausal status, depth of invasion, lymph node metastasis status, histologic classification, etc.

Conclusion

Our study suggests that the up-regulated expression of ICOSL protein in breast tumor cells can be associated with poor prognoses in invasive breast carcinomas.

Regulation of cancer immune escape: The roles of miRNAs in immune checkpoint proteins

Immune checkpoint proteins (ICPs) are regulators of immune system. The ICP dysregulation silences the host immune response to cancer-specific antigens, contributing to the occurrence and progress of various cancers. MiRNAs are regulatory molecules and function in mRNA silencing and post-transcriptional regulation of gene expression. MiRNAs that modulate the immunity via ICPs have received increasing attention. Many studies have shown that the expressions of ICPs are directly or indirectly repressed by miRNAs in multiple types of cancers. MiRNAs are also subject to regulation by ICPs. In this review, recent studies of the relationship between miRNAs and ICPs (including the PD-1, PD-L1, CTLA-4, ICOS, B7-1, B7-2, B7-H2, B7-H3, CD27, CD70, CD40, and CD40L) in cancer immune escape are comprehensively discussed, which provide critical detailed mechanistic insights into the functions of the miRNA-ICP axes and their effects on immune escape, and will be beneficial for the potential applications of immune checkpoint therapy and miRNA-based guidance for personalized medicine as well as for predicting the prognosis.

Expression of B7-H2 on CD8+ T cells in colorectal cancer microenvironment and its clinical significance

The knowledge about B7-H2 expression in tumor is growing, but many questions remain unresolved. Especially in human tumor microenvironment, little studies were done. To explore the expression and clinical significance of B7-H2 on T cells in colorectal cancer microenvironment, fresh tumor tissues and paired non-tumor tissues collected from 25 patients with colorectal cancer were made to research B7-H2 expression on the infiltrating T cells including CD8⁺ T cells and CD4⁺ T cells. Also, tumor bearing mice were sacrificed on day 5, day 10, day 15, day 20, day 25 and flow cytometry was used to analyze B7-H2 expression on CD8⁺ T cells and CD4⁺ T cells in mouse tumors and spleens. Then, it was found that B7-H2 expression on CD8⁺ T cells in patients' tumor tissues was significantly higher than in non-tumor tissues. The expression of B7-H2 on CD8⁺ T cells in tumor microenvironment was significantly higher in patients with age ≤60 years old and the stage I-II. The expression level of B7-H2 on CD8⁺ T cells in mouse tumors and spleens both reached the highest level at the early stage of inoculation (on day 5), decreased to the lowest level on day 10 and day 15 separately, and then gradually increased. In mouse spleens, B7-H2 expression on CD8⁺ T cells was all significantly higher than on CD4⁺ T cells in five time periods. So, in this study, it was found that B7-H2 expression on CD8⁺ T cells in tumor microenvironment was closely related to the progression of colorectal cancer.

Systemic T Cells Immunosuppression of Glioma Stem Cell-Derived Exosomes Is Mediated by Monocytic Myeloid-Derived Suppressor Cells

A major contributing factor to glioma development and progression is its ability to evade the immune system. Nano-meter sized vesicles, exosomes, secreted by glioma-stem cells (GSC) can act as mediators of intercellular communication to promote tumor immune escape. Here, we investigated the immunomodulatory properties of GCS-derived exosomes on different peripheral immune cell populations. Healthy donor peripheral blood mononuclear cells (PBMCs) stimulated with anti-CD3, anti-CD28 and IL-2, were treated with GSC-derived exosomes. Phenotypic characterization, cell proliferation, Th1/Th2 cytokine secretion and intracellular cytokine production were analysed by distinguishing among effector T cells, regulatory T cells and monocytes. In unfractionated PBMCs, GSC-derived exosomes inhibited T cell activation (CD25 and CD69 expression), proliferation and Th1 cytokine production, and did not affect cell viability or regulatory T-cell suppression ability. Furthermore, exosomes were able to enhance proliferation of purified CD4+ T cells. In PBMCs culture, glioma-derived exosomes directly promoted IL-10 and arginase-1 production and downregulation of HLA-DR by unstimulated CD14+ monocytic cells, that displayed an immunophenotype resembling that of monocytic myeloid-derived suppressor cells (Mo-MDSCs). Importantly, the removal of CD14+ monocytic cell fraction from PBMCs restored T-cell proliferation. The same results were observed with exosomes purified from plasma of glioblastoma patients. Our results indicate that glioma-derived exosomes suppress T-cell immune response by acting on monocyte maturation rather than on direct interaction with T cells. Selective targeting of Mo-MDSC to treat glioma should be considered with regard to how immune cells allow the acquirement of effector functions and therefore counteracting tumor progression.

MiR-138 exerts anti-glioma efficacy by targeting immune checkpoints

BACKGROUND

Antibody therapeutic targeting of the immune checkpoints cytotoxic T-lymphocyte-associated molecule 4 (CTLA-4) and programmed cell death 1 (PD-1) has demonstrated marked tumor regression in clinical trials. MicroRNAs (miRNAs) can modulate multiple gene transcripts including possibly more than one immune checkpoint and could be exploited as immune therapeutics.

METHODS

Using online miRNA targeting prediction algorithms, we searched for miRNAs that were predicted to target both PD-1 and CTLA-4. MiR-138 emerged as a leading candidate. The effects of miR-138 on CTLA-4 and PD-1 expression and function in T cells were determined and the therapeutic effect of intravenous administration of miR-138 was investigated in both immune-competent and -incompetent murine models of GL261 glioma.

RESULTS

Target binding algorithms predicted that miR-138 could bind the 3' untranslated regions of CTLA-4 and PD-1, which was confirmed with luciferase expression assays. Transfection of human CD4+ T cells with miR-138 suppressed expression of CTLA-4, PD-1, and Forkhead box protein 3 (FoxP3) in transfected human CD4+ T cells. In vivo miR-138 treatment of GL261 gliomas in immune-competent mice demonstrated marked tumor regression, a 43% increase in median survival time (P = .011), and an associated decrease in intratumoral FoxP3+ regulatory T cells, CTLA-4, and PD-1 expression. This treatment effect was lost in nude immune-incompetent mice and with depletion of CD4+ or CD8+ T cells, and miR-138 had no suppressive effect on glioma cells when treated directly at physiological in vivo doses.

CONCLUSIONS

MiR-138 exerts anti-glioma efficacy by targeting immune checkpoints which may have rapid translational potential as a novel immunotherapeutic agent.

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.

Synergistic effects of IL-4 and TNFα on the induction of B7-H1 in renal cell carcinoma cells inhibiting allogeneic T cell proliferation

Background

The importance of B7-H molecules for the T cell/tumor communication and its impact on renal cell carcinoma (RCC) progression and prognosis has been recently described. Cytokine treatment of RCC has earlier been shown to be beneficial in preclinical settings, but its clinical implementation has not proven to be as effective. This might be partially explained by the yet incomplete picture of cellular alterations in tumor cells upon cytokine treatment investigated in detail in this study.

Methods

RCC tumor cell lines were treated with different cytokines alone or in combination. The constitutive and/or cytokine-induced expression of cytokine receptors signaling components and B7-H molecules in RCC cells were analysed by qPCR and flow cytometry. A mcherry reporter gene construct containing B7-H1 promoter was cloned and its activity was determined upon transfection in cytokine-stimulated cells. Cytokine pretreated tumor cells were co-cultured with allogeneic CD8⁺ T cells from healthy donors and T cell proliferation as well as cytokine secretion was determined.

Results

A heterogeneous, but constitutive B7-H1,-H2,-H3 and H4 expression was found on human RCC cell lines. IL-4 and TNFα treatment led to strong synergistic induction of B7-H1 in RCC cells, whereas B7-H2 was only increased by TNFα. In contrast, B7-H3 and B7-H4 expression were not altered by these cytokines. Treatment of RCC cells with TNFα and IL-4 was accompanied by an activation of signaling molecules like NF-κB, IκB and STAT6. The cytokine-mediated up-regulation of B7-H1 was due to transcriptional control as determined by an increased B7-H1 promoter activity in the presence of IL-4 and TNFα. Despite HLA class I and LFA-1 were also increased, the cytokine-mediated up-regulation of B7-H1 was more pronounced and caused an inhibition of allospecifc CD8⁺ T cell proliferation.

Conclusion

Thus, IL-4 and TNFα, which could be released by immune cells of the tumor microenvironment, are able to control the B7-H1 expression in RCC thereby altering T cell responses. These data are of importance for understanding the complex interplay of tumor cells with immune cells orchestrated by a number of different soluble and membrane bound mediators and for the implementation of check point antibodies directed against B7-H1.

The role of B7 family molecules in hematologic malignancy

The B7 family consists of structurally related, cell-surface proteins that regulate immune responses by delivering costimulatory or coinhibitory signals through their ligands. Eight family members have been identified to date including CD80 (B7-1), CD86 (B7-2), CD274 (programmed cell death-1 ligand [PD-L1]), CD273 (programmed cell death-2 ligand [PD-L2]), CD275 (inducible costimulator ligand [ICOS-L]), CD276 (B7-H3), B7-H4, and B7-H6. B7 ligands are expressed on both lymphoid and nonlymphoid tissues. The importance of the B7 family in regulating immune responses is clear from their demonstrated role in the development of immunodeficiency and autoimmune diseases. Manipulation of the signals delivered by B7 ligands shows great potential in the treatment of cancers including leukemias and lymphomas and in regulating allogeneic T-cell responses after stem cell transplantation.

ICOS-ligand expression on plasmacytoid dendritic cells supports breast cancer progression by promoting the accumulation of immunosuppressive CD4+ T cells

Human breast tumors are infiltrated by memory CD4(+) T cells along with increased numbers of regulatory T cells (Treg) and plasmacytoid dendritic cells (pDC) that facilitate immune escape and correlate with poor prognosis. Here, we report that inducible costimulatory molecule (ICOS), a T cell costimulatory molecule of the CTLA4/PD1/CD28 family, is expressed mostly by tumor-associated Treg in primary breast tumors. A large proportion of these ICOS(+) Treg were Ki67(+) and this evident proliferative expansion was found to rely on interactions with tumor-associated pDC. Indeed, tumor-associated Treg highly expanded in presence of pDC but failed to proliferate under CD3/CD28 signal. In vitro experiments revealed that the addition of a neutralizing anti-ICOS antibody blocked pDC-induced Treg expansion and interleukin-10 secretion by memory CD4(+) T cells, establishing a pivotal role for ICOS in this process. Supporting these findings, the presence of ICOS(+) cells in clinical specimens of breast cancer correlated with a poor prognosis. Together, our results highlight an important relationship between Treg and pDC in breast tumors, and show that ICOS/ICOS-L interaction is a central event in immunosuppression of tumor-associated memory CD4(+) T cells. These findings strongly rationalize antibody-mediated ICOS blockade as a powerful clinical strategy to correct immune escape and promote therapeutic responses in breast cancer.

Preclinical xenograft models of human sarcoma show nonrandom loss of aberrations

BACKGROUND

Human tumors transplanted into immunodeficient mice (xenografts) are good preclinical models, and it is important to identify possible systematic changes during establishment and passaging in mice.

METHODS

High-resolution microarray-based comparative genomic hybridization (array CGH) was used to investigate how well a series of sarcoma xenografts, including 9 patient/xenograft pairs and 8 early versus late xenograft passage pairs, represented the patient tumor from which they originated.

RESULTS

In all analyses, the xenografts were more similar to their tumor of origin than other xenografts of the same type. Most changes in aberration patterns were toward a more normal genome complement, and the increased aberrations observed were mostly toward more loss. In general, the changes were scattered over the genome, but some changes were significant in osteosarcomas. These were rather focused and consistent with amplifications frequent in patient samples, involving the genes platelet-derived growth factor receptor A (PDGFRA), cysteine-rich hydrophobic domain 2 (CHIC2), FIP-like 1 (FIP1L1), ligand of numb-protein X1 (LNX1), RAS-like family 11 member B (RASL11B), and sec1 family domain containing 2 (SCFD2), probably a sign of continued tumor progression. Some changes that disappeared may have been involved in host-stroma interactions or chemotherapy resistance, possibly because of the absence of selection in the mouse.

CONCLUSIONS

Direct xenografts reflected well the genomic patterns of their tumors of origin. The few significant aberrations that were lost during passaging in immune-defective mice may have been caused by the lack of selection in the new host, whereas aberrations that were gained appeared to be the result of general tumor progression rather than model-specific artifacts.

Melanoma cells express ICOS ligand to promote the activation and expansion of T-regulatory cells

CD4(+)CD25(+)Foxp3(+) T-regulatory cells (Tregs) accumulate in tumors; however, little is known about how the tumor environment influences this process. Here we show that human melanomas express inducible T-cell costimulator ligand (ICOS-L/B7H) that can provide costimulation through ICOS for the expansion of activated Tregs maintaining high Foxp3 and CD25 expression as well as a suppressive function. Thus, ICOS-L expression by melanoma tumor cells may directly drive Treg activation and expansion in the tumor microenvironment as another mechanism of immune evasion.

Modulation of Immune Response by B7 Family Molecules in Tumor Microenvironments

The importance of co-stimulatory and co-inhibitory molecules has been confirmed on a grand scale; with the identification of new B7 family molecules, possessing both immune activating and inhibiting functions, this family has exploded onto the scene of immune regulation. Nowhere, however, has the role of B7 family members been more apparent than in the fight against cancer. In this review, we will discuss recent data regarding the essential and complex role of B7 family members in regulating the immune response within tumor microenvironment.

Cancer-associated immune-mediated syndromes: Pathogenic values and clinical implementation

The ability of tumors to provoke formation of cancer-associated secondary immunodeficiency (CASID) with predominant suppression of CMI and cancer-associated secondary immunodeficiency with clinical autoimmunity syndrome (CASICAS) with triggering of a set of the autoimmune deviations is appearing to be a key event in the restriction of hosts' anti-tumor immunity. Earlier the existence of the above-mentioned syndromes was demonstrated in BCC and GBM patients. In order to reach a point where immunological phenotypes in GBM and BCC can be clarified clinically and, partly, pathogenically, we have conducted a series of studies of typical and atypical types of immune responsiveness in patients with GBM and BCC. For GBM and BCC three scenarios of the involvement of the immune responsiveness have been established in a series of our studies, i.e., (i) malignancy with no immunopathology, (ii) malignancy as CASID, and (iii) malignancy as CASICAS. All of those scenarios demonstrated significant differences in their immune-mediated manifestations which, in turn, were proven to reveal close associative relationships with a specific clinicopathologic type and clinical manifestations of the tumor. CASID and CASICAS share two common features, i.e., (i) signs of immunodeficiency and (ii) a tandem of the deviations within the adaptive and innate links of the host immune responsiveness. At the same time, CASID and CASICAS are distinct pathogenically and clinically, and in terms of depth of the immune deviations observed, CASID patients manifest a breakage in both links, whereas in CASICAS patients, a breakage in the adaptive link would dominate. To get these differences clarified, we summarized major types of the immune imbalances and sets of clinical and clinicopathologic manifestations to illustrate the above-mentioned features in CASID and CASICAS patients. There are distinct close correlations between clinicopathologic features of the disease course and sets of the immune-mediated imbalances in patients harboring the tumors. The latter implicates a panel of the new immunodiagnostic and immunoprognostic criteria for patients with solid tumors, i.e., BCC, MCC and GB, which is of great value for clinical practice. In particular, the blood levels of some of the immunocompetent cells, state of their functional activity, serum titers of the antigenic markers and autoantibodies, apoptotic parameters, and others may be accepted as additional and clinically informative criteria to be implemented for immunological monitoring and immunotherapy of patients with solid tumors.

The new B7s: playing a pivotal role in tumor immunity

B7-H1, B7-DC, B7-H2, B7-H3, and B7-H4, all new additions to the B7 family, here termed "the new B7s," are emerging as important tools in directing immune function; each with unique, yet often overlapping functions. Clearly, each B7 molecule has developed its own indispensable niche in the immune system. The expression of both stimulatory and inhibitory B7 molecules seems to play an essential role in regulating the immune response to transformed cells through a variety of mechanisms. As specific niches of B7 family members continue to be dissected, their diagnostic and therapeutic potential becomes ever more apparent. In this review, we will discuss the role of the new B7s in activation and inhibition of antitumor immune responses, their prospects in diagnostics, and also potential and developing immunotherapy protocols.

Expression of Functional B7-H2 and B7.2 Costimulatory Molecules and Their Prognostic Implications in De novo Acute Myeloid Leukemia

PURPOSE

The B7 family molecules have been shown to regulate immune responses in both positive and negative fashions. Their roles in the progression of human cancers, however, are not well established. The aim of this study was to examine whether leukemic cells of acute myeloid leukemia express functional B7 family molecules and, if so, whether such expression has any clinical significance.

EXPERIMENTAL DESIGN

The expression of four B7 family molecules, B7.1, B7.2, B7-H1, and B7-H2, on leukemic cells from acute myeloid leukemia patients was analyzed by flow cytometry. The function of the expressed molecules was examined by the allogeneic mixed lymphocyte-leukemic cell reaction, and their relationship to the clinical data and survival was analyzed.

RESULTS

Although B7.1 and B7-H1 expressions were rare, the cells from a substantial number of acute myeloid leukemia cases expressed B7.2 and B7-H2 molecules [mean percentages of B7.2- and B7-H2-positive cells were 28.9% (n = 58) and 15.3% (n = 59), respectively]. Patients in whom >25% of leukemic cells expressed B7-H2 had significantly shorter survival, and this B7-H2 positivity had the strongest prognostic value when B7-H2 and other prognostic factors were analyzed together by multivariate analysis (P = 0.0108). Furthermore, B7.2 expression was associated with hyperleukocytosis (P = 0.026). Consistent with this finding, acute myeloid leukemia cells expressing B7.2 and B7-H2 induced allogeneic CD4+ T cells to proliferate and secrete interleukin-4 and interleukin-10 in vitro, effects that were partially blocked by antibodies against B7.2 and B7-H2.

CONCLUSIONS

Our results indicate the expression of functional B7.2 and B7-H2 molecules, and these molecules may facilitate progression of acute myeloid leukemia.

Expression and function of inducible costimulator on peripheral blood T cells in patients with systemic lupus erythematosus

OBJECTIVE

To investigate the role of inducible costimulator (ICOS) in the pathogenesis of SLE, we assessed its expression on peripheral blood CD4 and CD8 T cells and functional roles in patients with systemic lupus erythematosus (SLE).

METHODS

Expression of ICOS on peripheral blood CD4 and CD8 T cells and ICOS ligand (ICOSL) on peripheral blood CD19 B cells from patients with SLE, patients with rheumatoid arthritis (RA) and healthy volunteers were determined by two-colour flow cytometry. The functional costimulatory effects of ICOS on peripheral blood mononuclear cells (PBMC) were assessed by T-cell proliferative responses, cytokines, anti-double-stranded DNA (anti-dsDNA) antibody and total IgG production.

RESULTS

Peripheral blood CD4 and CD8 T cells expressing ICOS were significantly increased in patients with SLE compared with patients with RA and healthy subjects. Peripheral blood CD19 B cells expressing ICOSL in SLE were markedly reduced compared with RA. Proliferative responses of anti-CD3/ICOS costimulation were significantly higher than those of anti-CD3/hamster IgG (HIgG) in healthy subjects, but not in patients with SLE. Anti-CD3/ICOS-stimulated SLE PBMC secreted similar levels of IL-10 and IFN-gamma but a significantly lower level of IL-2 than healthy PBMC. Anti-CD3/ICOS-mediated costimulation significantly enhanced the production of anti-dsDNA antibodies and total IgG in patients with SLE.

CONCLUSION

Hyperexpression of ICOS on peripheral blood CD4 and CD8 T cells from patients with SLE contributed to the dysregulated T-cell proliferation, T-cell activation and pathogenic autoantibody production, which showed that the abnormality of ICOS costimulation may play an immunopathological role(s) in the pathogenesis of SLE.