Neutrophil infiltration into human gliomas

Cancer-related circulating and tumor-associated neutrophils - subtypes, sources and function

In recent years, the role of neutrophils in cancer biology has been a matter of increasing interest. Many patients with advanced cancer show high levels of neutrophilia, tumor neutrophils are connected to dismal prognosis, and the neutrophil-to-lymphocyte ratio has been introduced as a significant prognostic factor for survival in many types of cancer. Neutrophils constitute an important portion of the infiltrating immune cells in the tumor microenvironment, but controversy has long surrounded the function of these cells in the context of cancer. Multiple evidences have shown that neutrophils recruited to the tumor can acquire either protumor or antitumor function. These findings have led to the identification of multiple and heterogeneous neutrophil subsets in the tumor and circulation. In addition, tumor-associated neutrophils (TANs) were shown to demonstrate functional plasticity, driven by multiple factors present in the tumor microenvironment. In this review, we examine the current knowledge on cancer-related circulating neutrophils, their source and the function of the different subtypes, both mature and immature. We then discuss the pro vs antitumor nature of TANs in cancer, their functional plasticity and the mechanisms that regulate neutrophil recruitment and polarization. Although the vast majority of the knowledge on neutrophils in cancer comes from murine studies, recent work has been done on human cancer-related neutrophils. In the final paragraphs, we expand on the current knowledge regarding the role of neutrophils in human cancer and examine the question whether cancer-related neutrophils (circulating or intratumoral) could be a new possible target for cancer immunotherapy.

Targeted delivery of pixantrone to neutrophils by poly(sialic acid)-p-octadecylamine conjugate modified liposomes with improved antitumor activity

Based on the knowledge that poly(sialic acid) is a critical element for tumour development and that the receptors for its monomer are expressed on neutrophils, which play important roles in the progression and invasion of tumours, a poly(sialic acid)-p-octadecylamine conjugate (PSA-p-ODA) was synthesised and used to modify the surface of liposomal pixantrone (Pix-PSL) to improve the delivery of Pix to peripheral blood neutrophils (PBNs). The liposomes were fabricated using a remote loading technology via a pH gradient, and were then assessed for particle size, encapsulation efficiency, in vitro release, in vitro cytotoxicity, and pharmacokinetics. Simultaneously, in vitro and in vivo cellular uptake studies demonstrated that Pix-PSL provided an enhanced accumulation of Pix in PBNs. An in vivo study showed that the anti-tumour activity of Pix-PSL was superior to that of other formulations, probably owing to the efficient targeting of PBNs by Pix-PSL, after which PBNs containing Pix-PSL (Pix-PSL/PBNs) in the circulatory system are recruited by the tumour microenvironment. These findings suggest that PSA-p-ODA-decorated liposomal Pix may provide a neutrophil-mediated drug delivery system (DDS) for the eradication of tumours, and thus represents a promising approach for the tumour targeting of chemotherapeutic treatments.

Targeting both tumour-associated CXCR2+ neutrophils and CCR2+ macrophages disrupts myeloid recruitment and improves chemotherapeutic responses in pancreatic ductal adenocarcinoma

OBJECTIVE

Chemokine pathways are co-opted by pancreatic adenocarcinoma (PDAC) to facilitate myeloid cell recruitment from the bone marrow to establish an immunosuppressive tumour microenvironment (TME). Targeting tumour-associated CXCR2⁺neutrophils (TAN) or tumour-associated CCR2⁺ macrophages (TAM) alone improves antitumour immunity in preclinical models. However, a compensatory influx of an alternative myeloid subset may result in a persistent immunosuppressive TME and promote therapeutic resistance. Here, we show CCR2 and CXCR2 combined blockade reduces total tumour-infiltrating myeloids, promoting a more robust antitumour immune response in PDAC compared with either strategy alone.

METHODS

Blood, bone marrow and tumours were analysed from PDAC patients and controls. Treatment response and correlative studies were performed in mice with established orthotopic PDAC tumours treated with a small molecule CCR2 inhibitor (CCR2i) and CXCR2 inhibitor (CXCR2i), alone and in combination with chemotherapy.

RESULTS

A systemic increase in CXCR2⁺ TAN correlates with poor prognosis in PDAC, and patients receiving CCR2i showed increased tumour-infiltrating CXCR2⁺ TAN following treatment. In an orthotopic PDAC model, CXCR2 blockade prevented neutrophil mobilisation from the circulation and augmented chemotherapeutic efficacy. However, depletion of either CXCR2⁺ TAN or CCR2⁺ TAM resulted in a compensatory response of the alternative myeloid subset, recapitulating human disease. This was overcome by combined CCR2i and CXCR2i, which augmented antitumour immunity and improved response to FOLFIRINOX chemotherapy.

CONCLUSION

Dual targeting of CCR2⁺ TAM and CXCR2⁺ TAN improves antitumour immunity and chemotherapeutic response in PDAC compared with either strategy alone.

Neutrophilia as a biomarker for overall survival in newly diagnosed high-grade glioma patients undergoing chemoradiation

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Inflammation has been associated with poor outcome in various cancer histologies.

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In high-grade gliomas treated with concurrent temozolomide and radiation, pretreatment neutrophilia may be a significant prognosis factor for overall survival.

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In addition with previously available markers, this independent cost-effective biomarker could help identifying patients with worsened prognosis.

Objective

To study the prognostic value of neutrophil disorders in a retrospective cohort of high-grade glioma patients receiving definitive concurrent temozolomide and radiation.

Materials and methods

Clinical records of consecutive patients treated in our Institution between January 2005 and December 2010 with concurrent temozolomide (75 mg/m² daily) and radiation were collected. The prognostic value of pretreatment neutrophilia on survival, defined as a neutrophil count exceeding 7 G/L, was examined.

Results

We identified 164 patients, all treated with concurrent temozolomide-based chemoradiotherapy. Initial surgery was achieved in most (75%), with resection > 90% in 55 patients (34%). Total 151 patients (92%) had glioblastoma, and 13 patients (8%) had WHO grade III glioma. Eighty-two patients (50%) displayed pretreatment neutrophilia. Neutrophilia was not associated with concurrent or adjuvant temodal discontinuation (p > 0.3). The 2-year actuarial overall survival was 45%. Steroid consumption, i.e. 60 mg or more of daily prednisolone, increased pretreatment neutrophil count (p = 0.005). In univariate analysis, neutrophilia was associated with worse overall survival (p = 0.019), as well as age ≥ 65 years (p = 0.009), surgical resection < 90% (p = 0.003) and prednisolone consumption ≥ 60 mg/day (p = 0.016). In multivariate analysis, neutrophilia (p = 0.013), age ≥ 65 (p = 0.001), and surgical tumor resection < 90% (p = 0.010) independently decreased overall survival, while, steroid consumption was not (p = 0.088).

Conclusion

In high-grade gliomas treated with concurrent temozolomide and radiation, pretreatment neutrophilia may be a significant prognosis factor for overall survival. In addition with previously available markers, this independent cost-effective biomarker could help identifying patients with worsened prognosis.

Dexamethasone-induced leukocytosis is associated with poor survival in newly diagnosed glioblastoma

Despite its well-characterized side effects, dexamethasone is widely used in the pre-, peri- and postoperative neurosurgical setting due to its effective relief of tumor-induced symptoms through the reduction of tumor-associated edema. However, some patients show laboratory-defined dexamethasone induced elevation of white blood cell count, and its impact on glioblastoma progression is unknown. We retrospectively analyzed 113 patients with newly diagnosed glioblastoma to describe the incidence, risk factors and clinical features of dexamethasone-induced leukocytosis in primary glioblastoma patients. We further conducted an immunohistochemical analysis of the granulocyte and lymphocyte tumor-infiltration in the available corresponding histological sections. Patient age was identified to be a risk factor for the development of dexamethasone-induced leukocytosis (p < 0.05). The presence of dexamethasone-induced leukocytosis decreased overall survival (HR 2.25 95% CI [1.15-4.38]; p < 0.001) and progression-free survival (HR 2.23 95% CI [1.09-4.59]; p < 0.01). Furthermore, patients with dexamethasone-induced leukocytosis had significantly reduced CD15 + granulocytic- (p < 0.05) and CD3 + lymphocytic tumour infiltration (p < 0.05). We identified a subgroup of glioblastoma patients that are at particularly high risk for poor outcome upon dexamethasone treatment. Therefore, restrictive dosage or other edema reducing substances should be considered in patients with dexamethasone-induced leukocytosis.

Development and Validation of an Individualized Immune Prognostic Signature in Early-Stage Nonsquamous Non-Small Cell Lung Cancer

Importance

The prevalence of early-stage non-small cell lung cancer (NSCLC) is expected to increase with recent implementation of annual screening programs. Reliable prognostic biomarkers are needed to identify patients at a high risk for recurrence to guide adjuvant therapy.

Objective

To develop a robust, individualized immune signature that can estimate prognosis in patients with early-stage nonsquamous NSCLC.

Design, Setting, and Participants

This retrospective study analyzed the gene expression profiles of frozen tumor tissue samples from 19 public NSCLC cohorts, including 18 microarray data sets and 1 RNA-Seq data set for The Cancer Genome Atlas (TCGA) lung adenocarcinoma cohort. Only patients with nonsquamous NSCLC with clinical annotation were included. Samples were from 2414 patients with nonsquamous NSCLC, divided into a meta-training cohort (729 patients), meta-testing cohort (716 patients), and 3 independent validation cohorts (439, 323, and 207 patients). All patients underwent surgery with a negative surgical margin, received no adjuvant or neoadjuvant therapy, and had publicly available gene expression data and survival information. Data were collected from July 22 through September 8, 2016.

Main Outcomes and Measures

Overall survival.

Results

Of 2414 patients (1205 men [50%], 1111 women [46%], and 98 of unknown sex [4%]; median age [range], 64 [15-90] years), a prognostic immune signature of 25 gene pairs consisting of 40 unique genes was constructed using the meta-training data set. In the meta-testing and validation cohorts, the immune signature significantly stratified patients into high- vs low-risk groups in terms of overall survival across and within subpopulations with stage I, IA, IB, or II disease and remained as an independent prognostic factor in multivariate analyses (hazard ratio range, 1.72 [95% CI, 1.26-2.33; P < .001] to 2.36 [95% CI, 1.47-3.79; P < .001]) after adjusting for clinical and pathologic factors. Several biological processes, including chemotaxis, were enriched among genes in the immune signature. The percentage of neutrophil infiltration (5.6% vs 1.8%) and necrosis (4.6% vs 1.5%) was significantly higher in the high-risk immune group compared with the low-risk groups in TCGA data set (P < .003). The immune signature achieved a higher accuracy (mean concordance index [C-index], 0.64) than 2 commercialized multigene signatures (mean C-index, 0.53 and 0.61) for estimation of survival in comparable validation cohorts. When integrated with clinical characteristics such as age and stage, the composite clinical and immune signature showed improved prognostic accuracy in all validation data sets relative to molecular signatures alone (mean C-index, 0.70 vs 0.63) and another commercialized clinical-molecular signature (mean C-index, 0.68 vs 0.65).

Conclusions and Relevance

The proposed clinical-immune signature is a promising biomarker for estimating overall survival in nonsquamous NSCLC, including early-stage disease. Prospective studies are needed to test the clinical utility of the biomarker in individualized management of nonsquamous NSCLC.

One microenvironment does not fit all: heterogeneity beyond cancer cells

Human cancers exhibit formidable molecular heterogeneity, to a large extent accounting for the incomplete and transitory efficacy of current anti-cancer therapies. However, neoplastic cells alone do not manifest the disease, but conscript a battery of non-tumor cells to enable and sustain hallmark capabilities of cancer. Escaping immunosurveillance is one of such capabilities. Tumors evolve immunosuppressive microenvironment to subvert anti-tumor immunity. In this review, we will focus on tumor-associated myeloid cells, which constitute an essential part of the immune microenvironment and reciprocally interact with cancer cells to establish malignancy toward metastasis. The diversity and plasticity of these cells constitute another layer of heterogeneity, beyond the heterogeneity of cancer cells themselves. We envision that immune microenvironment co-evolves with the genetic heterogeneity of tumor. Addressing the question of how genetically distinct tumors shape and are shaped by unique immune microenvironment will provide an attractive rationale to develop novel immunotherapeutic modalities. Here, we discuss the complex nature of tumor microenvironment, with an emphasis on the cellular and functional heterogeneity among tumor-associated myeloid cells as well as immune environment heterogeneity in the context of a full spectrum of human breast cancers.

Tumor-Associated Neutrophils in Breast Cancer Subtypes

Background: Tumor associated neutrophils (TAN) are related to aggressiveness and a poor prognosis with human cancers. However, the relevance of TAN in breast cancer has not been previously investigated and here we sought to determine their presence among different subtypes. Methods: We analyzed patients with stage I-III breast cancers between 2006 and 2012. Tumors were divided into three subtypes: hormone-receptor [ HR]-positive, HER2-negative (HR+,HER2-ve); HER2-positive and triple negative (TN). Hematoxylin and eosin stained sections were examined and the number of TAN per 10 high power fields (HPF, 40x) was recorded. Tumors with >1 TAN per 10 HPF were considered TAN-positive. Fisher’s exact test was used to test for independence between qualitative variables, and logistic regression models were applied for multivariate analysis. Results: A total of 133 patients were assessed for inclusion and 105 were analyzed (28 excluded on various criteria). Some 72 tumors (69%) were classified as HR+, HER2-ve, 15 (14%) as HER2+ and 18 (17%) as TN. Totals of 16 TN (88%), 8 HER2+ (53%) and 4 HR+, HER2-ve tumors (5%) were TAN+ (p<0.001), including 79% of HR-ve tumors (19 of 24), in contrast to 11% of their HR+ve counterparts (9 of 81) (p<0.001). HER2 expression (p=0.023) and tumor grade (p<0.001) were also associated with TAN positivity. On multivariate analysis, only HR negativity (OR 16.85; 95% CI 4.4-64.6, p=<0.0001) was associated with a higher likelihood of TAN positivity. Conclusions: TAN are present in most TN tumors. We found an absence of HR expression to be the only predictor of TAN positivity. These results raise the question as to whether TAN, as part of the tumor microenvironment, have a role in the aggressiveness and progression of TN tumors and thus warrant further investigation in this breast cancer subtype, particularly in relation to response to treatment and prognosis.

Influence of neutrophil-lymphocyte ratio in prognosis of glioblastoma multiforme

Neutrophil-lymphocyte ratio (NLR) is a hematological marker of systemic inflammation and several studies demonstrate an association between a higher NLR and a worse prognosis in many malignancies. However, literature analyzing its prognostic value in glioblastoma multiforme (GBM) is still scarce. We intended to analyze the correlation of NLR with overall survival and progression-free survival in patients with GBM performing a retrospective review of the patients with diagnosis of GBM submitted to a resection surgery in the department of neurosurgery of a tertiary care hospital, between January/2005 and January/2013. 140 patients were included. Mean age at surgery was 62.9 ± 10.0 years and mean age at death was 64.4 ± 9.8 years. Mean overall survival was 19.4 ± 14.3 months and mean progression-free survival was 9.4 ± 8.7 months. There was no correlation of NLR, platelets-lymphocyte ratio (PLR) or absolute counts of neutrophils, lymphocytes and platelets with overall survival in multivariate analysis. However, a preoperative NLR ≤ 5 correlated with a shorter progression-free survival [HR 1.56 (SD 95% 1.04-2.34); p = 0.032]. We performed a subgroup analysis of patients who completed Stupp protocol. In this subgroup of 117 patients, a preoperative NLR > 7 correlated with a shorter overall survival [HR 1.65 (SD 95% 1.07-2.53); p = 0.023]. The results from our total cohort didn't confirm the correlation between a higher NRL and worse survival in GBM. However, in the subgroup analysis of patients who completed Stupp protocol, a higher NLR was an independent prognostic factor to a shorter overall survival, similar to existent literature data about GBM.

Neutrophils in Gliomas

Neutrophils are the most abundant white blood cells and are the first recruited to inflammatory sites. Neutrophils are an important component of the tumor stroma and can exert both anti-tumoral and pro-tumoral activities, depending on their maturation and activation state. In human gliomas, the number of circulating and infiltrating neutrophils correlates with the severity of the disease, indicating a prognostic and possible pro-tumoral role for these leukocytes. In glioma preclinical models, neutrophils promote tumor growth and orchestrate the resistance to anti-angiogenic therapies. Nevertheless, recent data indicate that neutrophils can be activated to directly kill tumor cells or to orchestrate the anti-tumoral response. Here, we review current knowledge about the role of neutrophils in glioma and their possible involvement in new strategies to improve current cancer therapies.

Blood-brain barrier pericyte importance in malignant gliomas: what we can learn from stroke and Alzheimer's disease

The pericyte, a constitutive component of the central nervous system, is a poorly understood cell type that envelops the endothelial cell with the intended purpose of regulating vascular flow and endothelial cell permeability. Previous studies of pericyte function have been limited to a small number of disease processes such as ischemic stroke and Alzheimer's disease. Recently, publications have postulated a link between glioma stem cell differentiation and pericyte function. These studies suggest that there may be an important interaction of pericytes with tumor cells and other components of the tumor microenvironment in malignant primary glial neoplasms, most notably glioblastoma. This potential cellular interaction underscores the need to pursue more investigations of pericytes in malignant brain tumor biology. In this review, we summarize the functional roles of pericytes, particularly focusing on changes in pericyte biology during response to immune cells, inflammation, and hypoxic conditions. The information presented is based on the available data from studies of pericyte function in other central nervous system diseases but will serve as a foundation for research investigations to further understand the role of pericytes in malignant gliomas.

Tumor Purity as an Underlying Key Factor in Glioma

Purpose: Glioma tissues consist of not only glioma cells but also glioma-associated nontumor cells, such as stromal cells and immune cells. These nontumor cells dilute the purity of glioma cells and play important roles in glioma biology. Currently, the implications of variation in glioma purity are not sufficiently clarified.Experimental Design: Here, tumor purity was inferred for 2,249 gliomas and 29 normal brain tissues from 5 cohorts. Based on the transcriptomic profiling method, we classified CGGA and TCGA-RNAseq cohorts as the RNAseq set for discovery. Cases from TCGA-microarray, REMBRANDT, and GSE16011 cohorts were grouped as a microarray set for validation. Tissues from the CGGA cohort were reviewed for histopathologic validation.Results: We found that glioma purity was highly associated with major clinical and molecular features. Low purity cases were more likely to be diagnosed as malignant entities and independently correlated with reduced survival time. Integrating glioma purity into prognostic nomogram significantly improved the predictive validity. Moreover, most recognized prognostic indicators were no longer significantly effective under different purity conditions. These results highlighted the clinical importance of glioma purity. Further analyses found distinct genomic patterns associated with glioma purity. Low purity cases were distinguished by enhanced immune phenotypes. Macrophages, microglia, and neutrophils were mutually associated and enriched in low purity gliomas, whereas only macrophages and neutrophils served as robust indicators for poor prognosis.Conclusions: Glioma purity and relevant nontumor cells within microenvironment confer important clinical, genomic, and biological implications, which should be fully valued for precise classification and clinical prediction. Clin Cancer Res; 23(20); 6279-91. ©2017 AACR.

Prognostic role of neutrophil lymphocyte ratio in patients with glioma

The purpose of this study was to evaluate the prognostic role of neutrophil lymphocyte ratio (NLR) in patients with glioma. PubMed, EMBASE, Cochrane Library and China National Knowledge Infrastructure were searched for relevant literature. The study and patient characteristics were extracted. Hazard ratios (HRs) with 95% confidence intervals (CIs) were pooled to estimate the prognostic role of NLR in patients with glioma. Subgroup analysis and sensitivity analysis were also performed. Six studies with 1,021 patients were included. The pooled HR of elevated NLR for OS in patients with glioma was 1.48 (95% CI, 1.25-1.76). Among the included studies, five studies used 4 as the cut-off value of NLR. The pooled HR for OS of the five studies was 1.67 (95% CI, 1.37-2.03). No significant heterogeneity was observed (I² = 42.4%, P=0. 122). Publication bias was not present. Elevated NLR was associated with poorer overall survival in patients with glioma.

Neutrophils in cancer

Neutrophils play an important role in cancer. This does not only relate to the well-established prognostic value of the presence of neutrophils, either in the blood or in tumor tissue, in the context of cancer progression or for the monitoring of therapy, but also to their active role in the progression of cancer. In the current review, we describe what is known in general about the role of neutrophils in cancer. What is emerging is a complex, rather heterogeneous picture with both pro- and anti-tumorigenic roles, which apparently differs with cancer type and disease stage. Furthermore, we will discuss the well-known role of neutrophils as myeloid-derived suppressor cells (MDSC), and also on the role of neutrophils as important effector cells during antibody therapy in cancer. It is clear that neutrophils contribute substantially to cancer progression in multiple ways, and this includes both direct effects on the cancer cells and indirect effect on the tumor microenvironment. While in many cases neutrophils have been shown to promote tumor progression, for instance by acting as MDSC, there are also protective effects, particularly when antibody immunotherapy is performed. A better understanding of the role of neutrophils is likely to provide opportunities for immunomodulation and for improving the treatment of cancer patients.

The Impact of the Tumor Microenvironment on the Properties of Glioma Stem-Like Cells

Glioblastoma is the most common and highly malignant primary brain tumor, and patients affected with this disease exhibit a uniformly dismal prognosis. Glioma stem-like cells (GSCs) are a subset of cells within the bulk tumor that possess self-renewal and multi-lineage differentiation properties similar to somatic stem cells. These cells also are at the apex of the cellular hierarchy and cause tumor initiation and expansion after chemo-radiation. These traits make them an attractive target for therapeutic development. Because GSCs are dependent on the brain microenvironment for their growth, and because non-tumorigenic cell types in the microenvironment can influence GSC phenotypes and treatment response, a better understanding of these cell types is needed. In this review, we provide a focused overview of the contributions from the microenvironment to GSC homing, maintenance, phenotypic plasticity, and tumor initiation. The interaction of GSCs with the vascular compartment, mesenchymal stem cells, immune system, and normal brain cell types are discussed. Studies that provide mechanistic insight into each of these GSC–microenvironment interactions are warranted in the future.

Neutrophil-mediated anticancer drug delivery for suppression of postoperative malignant glioma recurrence

Cell-mediated drug-delivery systems have received considerable attention for their enhanced therapeutic specificity and efficacy in cancer treatment. Neutrophils (NEs), the most abundant type of immune cells, are known to penetrate inflamed brain tumours. Here we show that NEs carrying liposomes that contain paclitaxel (PTX) can penetrate the brain and suppress the recurrence of glioma in mice whose tumour has been resected surgically. Inflammatory factors released after tumour resection guide the movement of the NEs into the inflamed brain. The highly concentrated inflammatory signals in the brain trigger the release of liposomal PTX from the NEs, which allows delivery of PTX into the remaining invading tumour cells. We show that this NE-mediated delivery of drugs efficiently slows the recurrent growth of tumours, with significantly improved survival rates, but does not completely inhibit the regrowth of tumours.

The effect of resveratrol, its naturally occurring derivatives and tannic acid on the induction of cell cycle arrest and apoptosis in rat C6 and human T98G glioma cell lines

Resveratrol (3,5,4'-trihydroxy-trans-stilbene) is a potent chemopreventive and potentially cancer therapeutic agent. Since rapid metabolism limits resveratrol bioavailability, derivatives less prone to metabolic transformation are being sought and tested. We evaluated the effect of resveratrol, and its analogs (pterostilbene and 3,5,4'-trimethoxystilbene) along with tannic acid, on cell cycle and apoptosis in rat C6 and human T98G glioma cells. At concentration ranges both lower and higher than IC₅₀ calculated based on MTT assay, all these polyphenols affected the cell cycle distribution. However, resveratrol and pterostilbene increased the percentage of the cells in S phase, while trimethoxystilbene (TMS) caused a massive accumulation of cells at the G2/M phase of the cell cycle. Tannic acid had no effect on cell cycle distribution in C6 cells, but increased the number of dead cells in both glioma cell lines. The ability to induce apoptosis by tannic acid and stilbenes was confirmed by phosphatidylserine externalization, the loss of mitochondrial membrane potential and the level of cleaved caspase-3. The apoptosis rate was most significantly increased by TMS and this was related to p53 induction. These results indicate that methoxylated stilbenes are efficient inhibitors of glioma cell proliferation and apoptosis inducers and might be considered adjuvants in glioma therapy.

An immunocompetent mouse model of human glioblastoma

Orthotopic xenotransplantation studies represent the final stage in preclinical cancer research and could facilitate the implementation of precision medicine. To date, these xenografts have been tested in immunodeficient animals, but complete elimination of the adaptive immunity is a significant drawback. We present a method of efficient human glioblastoma (GBM) cell engraftment in adult mice with intact immune systems, mediated by a transient blockade of T-cell co-stimulation. Compared to transplants grown in immunodeficient hosts, the resulting tumors more accurately resemble the clinical pathophysiology of patient GBMs, which are characterized by blood-brain-barrier leakage and strong neo-vascularization. We expect our method to have great utility for studying human tumor cell biology, particularly in the field of cancer immunotherapy and in studies on microenvironmental interactions. Given the straightforward approach, the method may also be applicable to other tumor types and additional model organisms.

Glioblastoma-synthesized G-CSF and GM-CSF contribute to growth and immunosuppression: Potential therapeutic benefit from dapsone, fenofibrate, and ribavirin

Increased ratio of circulating neutrophils to lymphocytes is a common finding in glioblastoma and other cancers. Data reviewed establish that any damage to brain tissue tends to cause an increase in G-CSF and/or GM-CSF (G(M)-CSF) synthesized by the brain. Glioblastoma cells themselves also synthesize G(M)-CSF. G(M)-CSF synthesized by brain due to damage by a growing tumor and by the tumor itself stimulates bone marrow to shift hematopoiesis toward granulocytic lineages away from lymphocytic lineages. This shift is immunosuppressive and generates the relative lymphopenia characteristic of glioblastoma. Any trauma to brain—be it blunt, sharp, ischemic, infectious, cytotoxic, tumor encroachment, or radiation—increases brain synthesis of G(M)-CSF. G(M)-CSF are growth and motility enhancing factors for glioblastomas. High levels of G(M)-CSF contribute to the characteristic neutrophilia and lymphopenia of glioblastoma. Hematopoietic bone marrow becomes entrained with, directed by, and contributes to glioblastoma pathology. The antibiotic dapsone, the lipid-lowering agent fenofibrate, and the antiviral drug ribavirin are Food and Drug Administration– and European Medicines Agency–approved medicines that have potential to lower synthesis or effects of G(M)-CSF and thus deprive a glioblastoma of some of the growth promoting contributions of bone marrow and G(M)-CSF.

The Microenvironmental Landscape of Brain Tumors

The brain tumor microenvironment (TME) is emerging as a critical regulator of cancer progression in primary and metastatic brain malignancies. The unique properties of this organ require a specific framework for designing TME-targeted interventions. Here, we discuss a number of these distinct features, including brain-resident cell types, the blood-brain barrier, and various aspects of the immune-suppressive environment. We also highlight recent advances in therapeutically targeting the brain TME in cancer. By developing a comprehensive understanding of the complex and interconnected microenvironmental landscape of brain malignancies we will greatly expand the range of therapeutic strategies available to target these deadly diseases.

Neutrophils as active regulators of the immune system in the tumor microenvironment

In recent years, the role of immune cells in tumor progression has been a matter of increasing interest. Neutrophils constitute an important portion of the immune cells infiltrating the tumor microenvironment. Traditionally viewed as the first line of defense against infections, it is now well accepted that neutrophils also have an important role in multiple aspects of cancer biology. Multiple and heterogeneous neutrophil subsets have been identified in tumors and in circulation. Evidence from many studies now supports the notion that tumor-associated neutrophils (TANs) show functional plasticity driven by multiple factors present in the tumor microenvironment. In this review, we first concisely discuss the pro-tumor vs. anti-tumor nature of neutrophils in cancer, their functional plasticity, and the mechanisms that regulate neutrophil polarization. We then expand on the various crosstalks and mutual effects between TANs and other tumor-infiltrating immune cell types, emphasizing the active role of neutrophils as regulators of the immune system, promoting or inhibiting the establishment of a permissive tumor microenvironment. Finally, the possible modulation of cancer-related neutrophils by therapies directed toward immune checkpoints is discussed briefly.

The Complex Role of Neutrophils in Tumor Angiogenesis and Metastasis

Chronic inflammation fosters cancer development and progression and also modulates tumor responses to anticancer therapies. Neutrophils are key effector cells in innate immunity and are known to play a critical role in various inflammatory disorders. However, the functions of neutrophils in cancer pathogenesis have been largely neglected until recently and still remain poorly characterized compared with other immune cells in the tumor microenvironment. We highlight recent findings on the mechanisms by which tumor cells, in cooperation with tumor-associated stromal cells, induce expansion, recruitment, and polarization of neutrophils. We also review the multifaceted roles that neutrophils play in different aspects of cancer development and progression, with an emphasis on tumor angiogenesis and metastasis.

CD8 T Cell-Independent Antitumor Response and Its Potential for Treatment of Malignant Gliomas

Malignant brain tumors continue to represent a devastating diagnosis with no real chance for cure. Despite an increasing list of potential salvage therapies, standard-of-care for these patients has not changed in over a decade. Immunotherapy has been seen as an exciting option, with the potential to offer specific and long lasting tumor clearance. The “gold standard” in immunotherapy has been the development of a tumor-specific CD8 T cell response to potentiate tumor clearance and immunological memory. While many advances have been made in the field of immunotherapy, few therapies have seen true success. Many of the same principles used to develop immunotherapy in tumors of the peripheral organs have been applied to brain tumor immunotherapy. The immune-specialized nature of the brain should call into question whether this approach is appropriate. Recent results from our own experiments require a rethinking of current dogma. Perhaps a CD8 T cell response is not sufficient for an organ as immunologically unique as the brain. Examination of previously elucidated principles of the brain’s immune-specialized status and known immunological preferences should generate discussion and experimentation to address the failure of current therapies.

The IL-8/IL-8R Axis: A Double Agent in Tumor Immune Resistance

Interleukin-8 (IL-8, CXCL8) is a pro-inflammatory chemokine produced by various cell types to recruit leukocytes to sites of infection or tissue injury. Acquisition of IL-8 and/or its receptors CXCR1 and CXCR2 are known to be a relatively common occurrence during tumor progression. Emerging research now indicates that paracrine signaling by tumor-derived IL-8 promotes the trafficking of neutrophils and myeloid-derived suppressor cells (MDSCs) into the tumor microenvironment, which have the ability to dampen anti-tumor immune responses. Furthermore, recent studies have also shown that IL-8 produced by the tumor mass can induce tumor cells to undergo the transdifferentiation process epithelial-to-mesenchymal transition (EMT) in which tumor cells shed their epithelial characteristics and acquire mesenchymal characteristics. EMT can increase metastatic dissemination, stemness, and intrinsic resistance, including to killing by cytotoxic immune cells. This review highlights the dual potential roles that the inflammatory cytokine IL-8 plays in promoting tumor resistance by enhancing the immunosuppressive microenvironment and activating EMT, and then discusses the potential for targeting the IL-8/IL-8 receptor axis to combat these various resistance mechanisms.

Toward a noncytotoxic glioblastoma therapy: blocking MCP-1 with the MTZ Regimen

To improve the prognosis of glioblastoma, we developed an adjuvant treatment directed to a neglected aspect of glioblastoma growth, the contribution of nonmalignant monocyte lineage cells (MLCs) (monocyte, macrophage, microglia, dendritic cells) that infiltrated a main tumor mass. These nonmalignant cells contribute to glioblastoma growth and tumor homeostasis. MLCs comprise of approximately 10%-30% of glioblastoma by volume. After integration into the tumor mass, these become polarized toward an M2 immunosuppressive, pro-angiogenic phenotype that promotes continued tumor growth. Glioblastoma cells initiate and promote this process by synthesizing 13 kDa MCP-1 that attracts circulating monocytes to the tumor. Infiltrating monocytes, after polarizing toward an M2 phenotype, synthesize more MCP-1, forming an amplification loop. Three noncytotoxic drugs, an antibiotic - minocycline, an antihypertensive drug - telmisartan, and a bisphosphonate - zoledronic acid, have ancillary attributes of MCP-1 synthesis inhibition and could be re-purposed, singly or in combination, to inhibit or reverse MLC-mediated immunosuppression, angiogenesis, and other growth-enhancing aspects. Minocycline, telmisartan, and zoledronic acid - the MTZ Regimen - have low-toxicity profiles and could be added to standard radiotherapy and temozolomide. Re-purposing older drugs has advantages of established safety and low drug cost. Four core observations support this approach: 1) malignant glioblastoma cells require a reciprocal trophic relationship with nonmalignant macrophages or microglia to thrive; 2) glioblastoma cells secrete MCP-1 to start the cycle, attracting MLCs, which subsequently also secrete MCP-1 perpetuating the recruitment cycle; 3) increasing cytokine levels in the tumor environment generate further immunosuppression and tumor growth; and 4) MTZ regimen may impede MCP-1-driven processes, thereby interfering with glioblastoma growth.

Human neutrophils: Their role in cancer and relation to myeloid-derived suppressor cells

Increased frequencies of peripheral blood neutrophils as well as tumor-infiltrating (associated) neutrophils (TAN) have been observed in many tumor entities. Although the most frequent cell type in the peripheral blood, neutrophils are outnumbered by other leukocyte subsets in the tumor microenvironment. Nevertheless, a number of recent meta-analyses identified TAN as well as high neutrophil-lymphocyte ratio in the blood as one of the most powerful immunologic prognostic parameters in human oncology. This clinical impact is based on an intense bidirectional crosstalk of neutrophils and tumor cells resulting in changes in neutrophil as well as tumor cell biology. These changes eventually lead to TAN equipped with various tumor promoting features, which enhance angiogenesis, cancer cell invasion and metastasis. Many of the pro-tumor features of TAN are shared with PMN-MDSC (myeloid-derived suppressor cells). Consequently, the distinction of these two cell populations is a matter of intensive debate and also specifically discussed in this article. The importance of neutrophils in cancer progression has triggered numerous efforts to therapeutically target these cells. Current strategies in this area focus on the inhibition of either TAN recruitment or pro-tumorigenic function.

The Response of Macrophages and Neutrophils to Hypoxia in the Context of Cancer and Other Inflammatory Diseases

Lack of oxygen (hypoxia) is a hallmark of a multitude of acute and chronic diseases and can be either beneficial or detrimental for organ restitution and recovery. In the context of inflammation, hypoxia is particularly important and can significantly influence the course of inflammatory diseases. Macrophages and neutrophils, the chief cellular components of innate immunity, display distinct properties when exposed to hypoxic conditions. Virtually every aspect of macrophage and neutrophil function is affected by hypoxia, amongst others, morphology, migration, chemotaxis, adherence to endothelial cells, bacterial killing, differentiation/polarization, and protumorigenic activity. Prominent arenas of macrophage and neutrophil function, for example, acute/chronic inflammation and the microenvironment of solid tumors, are characterized by low oxygen levels, demonstrating the paramount importance of the hypoxic response for proper function of these cells. Members of the hypoxia-inducible transcription factor (HIF) family emerged as pivotal molecular regulators of macrophages and neutrophils. In this review, we will summarize the molecular responses of macrophages and neutrophils to hypoxia in the context of cancer and other chronic inflammatory diseases and discuss the potential avenues for therapeutic intervention that arise from this knowledge.

Glioblastoma-infiltrated innate immune cells resemble M0 macrophage phenotype

Glioblastomas are highly infiltrated by diverse immune cells, including microglia, macrophages, and myeloid-derived suppressor cells (MDSCs). Understanding the mechanisms by which glioblastoma-associated myeloid cells (GAMs) undergo metamorphosis into tumor-supportive cells, characterizing the heterogeneity of immune cell phenotypes within glioblastoma subtypes, and discovering new targets can help the design of new efficient immunotherapies. In this study, we performed a comprehensive battery of immune phenotyping, whole-genome microarray analysis, and microRNA expression profiling of GAMs with matched blood monocytes, healthy donor monocytes, normal brain microglia, nonpolarized M0 macrophages, and polarized M1, M2a, M2c macrophages. Glioblastoma patients had an elevated number of monocytes relative to healthy donors. Among CD11b⁺ cells, microglia and MDSCs constituted a higher percentage of GAMs than did macrophages. GAM profiling using flow cytometry studies revealed a continuum between the M1- and M2-like phenotype. Contrary to current dogma, GAMs exhibited distinct immunological functions, with the former aligned close to nonpolarized M0 macrophages.

Serum exosomes and cytokines promote a T-helper cell type 2 environment in the peripheral blood of glioblastoma patients

BACKGROUND

Glioblastoma (GBM) is an aggressive infiltrative brain tumor with a particularly poor prognosis that is characterized by microvascular proliferation, necrotic tissue, and significant infiltration of M2-like monocytes. Compromised barrier function in tumor vasculature might be expected to permit communication between the tumor microenvironment and peripheral blood.

METHODS

To ascertain whether tumor-derived vesicles and/or factors might reach the bloodstream and what effects these molecules have on the peripheral compartment, we analyzed blood samples collected from primary GBM patients.

RESULTS

Notably, a significant number of patient sera samples contained tumor exosome-reactive immunoglobulin (Ig)G2 and IgG4 antibody isotypes, which are consistent with Th2 immunity. M2-like monocytes expressing CD14+ and CD163+, another indicator of Th2 bias, are elevated in GBM patient blood and associated with high serum concentrations of colony-stimulating factor 2 and 3, as well as interleukin-2, -4, and -13, the latter 2 cytokines being hallmarks of Th2 immunity. GBM patient sera samples induce high levels of CD163 expression when added to normal monocytes, providing mechanistic evidence of a basis for Th2 bias. Fractionation of GBM patient sera into samples enriched for exosomes or soluble factors proved that both fractions are capable of inducing CD163 expression in normal monocytes.

CONCLUSIONS

The results of the current study indicate a Th2 bias in the periphery of GBM patients, likely as a result of products elaborated by the tumor. Consequentially, through immune modulation these brain tumors exert systemic effects beyond the confines of the CNS.

Neutrophils in the Tumor Microenvironment

Neutrophils are the first responders to sites of acute tissue damage and infection. Recent studies suggest that in addition to neutrophil apoptosis, resolution of neutrophil inflammation at wounds can be mediated by reverse migration from tissues and transmigration back into the vasculature. In settings of chronic inflammation, neutrophils persist in tissues, and this persistence has been associated with cancer progression. However, the role of neutrophils in the tumor microenvironment remains controversial, with evidence for both pro- and anti-tumor roles. Here we review the mechanisms that regulate neutrophil recruitment and resolution at sites of tissue damage, with a specific focus on the tumor microenvironment. We discuss the current understanding as to how neutrophils alter the tumor microenvironment to support or hinder cancer progression, and in this context outline gaps in understanding and important areas of inquiry.

Pre-treatment neutrophil-to-lymphocyte ratio is associated with neutrophil and T-cell infiltration and predicts clinical outcome in patients with glioblastoma

BACKGROUND

Markers of systemic inflammation are correlated with patient survival in various cancers. The prognostic value of neutrophil-to-lymphocyte ratio (NLR) was compared with that of platelet-to-lymphocyte ratio (PLR) in patients with glioblastoma. The association of NLR with neutrophil and T- cell infiltration was also explored.

METHODS

A total of 152 patients with glioblastoma were retrospectively analyzed. Clinical information was obtained from electronic medical records. Kaplan-Meier analysis and the Cox proportional hazards models were used to examine the survival function of pre-treatment NLR and PLR in these glioblastoma patients. Neutrophil and CD3(+) T-cell infiltration was assessed by immunohistochemical staining of tissue microarray cores from glioblastomas.

RESULTS

Pre-treatment NLR levels were significantly correlated with overall survival (OS) in glioblastoma patients (multivariate hazard ratio =1.050; 95% confidence interval, 1.003-1.100; P = 0.037). Despite the correlation between NLR and PLR (R = 0.509, P < 0.001), NLR was superior to PLR as a prognostic factor. High pre-treatment NLR (≥4 versus < 4) was significantly associated with high neutrophil infiltration and low CD3(+) T-cell infiltration into tumors, and predicted poor OS (mean, 10.6 vs. 17.9 months, P < 0.001).

CONCLUSIONS

Pre-treatment NLR is of prognostic significance independent of MGMT status and is superior to PLR as a prognostic factor. Our results demonstrate a correlation between elevated peripheral blood NLR levels and increased tumor neutrophil infiltration/decreased CD3(+) T-cell infiltration.

Enhanced neutrophil activity is associated with shorter time to tumor progression in glioblastoma patients

Glioblastoma multiforme (GBM) is a highly malignant tumor with a poor outcome that is often positive for human cytomegalovirus (HCMV). GBM patients often have excessive numbers of neutrophils and macrophages near and within the tumor. Here, we characterized the cytokine patterns in the blood of GBM patients with and without Valganciclovir treatment. Furthermore, we determined whether neutrophil activation is related to HCMV status and patient outcome. Blood samples for analyses of cytokines and growth factors were collected from 42 GBM patients at the time of diagnosis (n = 42) and at weeks 12 and 24 after surgery. Blood neutrophils of 28 GBM patients were examined for CD11b expression. The levels of pro- and anti-inflammatory cytokines and chemokines-including interleukin (IL)-1β, IL-2, IL-6, IL-8, IL-10, IL-12p70, IL-17A, transforming growth factor (TGF)-β1, interferon-γ, interferon-α, tumor necrosis factor α, and monocyte chemoattractant protein (MCP)-1were analyzed with a bead-based flow cytometry assay. During the first six months after surgery, neutrophil activity was increased in 12 patients and was unchanged or decreased in 16. Patients with increased neutrophil activity had enhanced IL-12p70, high grade HCMV and a shorter time to tumor progression (TTP) than patients without or decreased neutrophil activity (median TTP; 5.4 vs. 12 months, 95% confidence interval; 1.6-10 vs. 0.1-0.6, hazard ratio = 3 vs. 0.4, p = 0.004). The levels of IL-12p70 were significantly decreased in Valganciclovir treated patients (n = 22, T 12W vs. T 24W, p = 0.03). In conclusion, our findings suggest that neutrophil activation is an early sign of tumor progression in GBM patients.

Phagocytes as Corrupted Policemen in Cancer-Related Inflammation

Inflammation is a key component of the tumor microenvironment. Tumor-associated macrophages (TAMs) and tumor-associated neutrophils (TANs) are prototypic inflammatory cells in cancer-related inflammation. Macrophages provide a first line of resistance against infectious agents but in the ecological niche of cancer behave as corrupted policemen. TAMs promote tumor growth and metastasis by direct interactions with cancer cells, including cancer stem cells, as well as by promoting angiogenesis and tissue remodeling and suppressing effective adaptive immunity. In addition, the efficacy of chemotherapy, radiotherapy, and checkpoint blockade inhibitors is profoundly affected by regulation of TAMs. In particular, TAMs can protect and rescue tumor cells from cytotoxic therapy by orchestrating a misguided tissue repair response. Following extensive preclinical studies, there is now proof of concept that targeting tumor-promoting macrophages by diverse strategies (e.g., Trabectedin, anti-colony-stimulating factor-1 receptor antibodies) can result in antitumor activity in human cancer and further studies are ongoing. Neutrophils have long been overlooked as a minor component of the tumor microenvironment, but there is evidence for an important role of TANs in tumor progression. Targeting phagocytes (TAMs and TANs) as corrupted policemen in cancer may pave the way to innovative therapeutic strategies complementing cytoreductive therapies and immunotherapy.

Nicotine mediates hypochlorous acid-induced nuclear protein damage in mammalian cells

Activated neutrophils secrete hypochlorous acid (HOCl) into the extracellular space of inflamed tissues. Because of short diffusion distance in biological fluids, HOCl-damaging effect is restricted to the extracellular compartment. The current study aimed at investigating the ability of nicotine, a component of tobacco and electronic cigarettes, to mediate HOCl-induced intracellular damage. We report, for the first time, that HOCl reacts with nicotine to produce nicotine chloramine (Nic-Cl). Nic-Cl caused dose-dependent damage to proliferating cell nuclear antigen (PCNA), a nuclear protein, in cultured mammalian lung and kidney cells. Vitamin C, vitamin E analogue (Trolox), glutathione, and N-acetyl-L-cysteine inhibited the Nic-Cl-induced PCNA damage, implicating oxidation in PCNA damage. These findings point out the ability of nicotine to mediate HOCl-induced intracellular damage and suggest antioxidants as protective measures. The results also raise the possibility that Nic-Cl can be created in the inflamed tissues of tobacco and electronic cigarette smokers and may contribute to smoking-related diseases.

Interleukin-8 is a key mediator of FKBP51-induced melanoma growth, angiogenesis and metastasis

Background:

FKBP51 is overexpressed in melanoma and impacts tumour cell properties. However, its comprehensive role in melanoma pathogenesis and underlying mechanism(s) remain elusive.

Methods:

FKBP51 was stably silenced in aggressive melanoma cell lines and its effect examined in vitro and in mouse model. Histological/immunohistochemical analyses were performed to confirm metastasis, angiogenesis and neutrophil infiltration. Gene expression was analyzed by qRT–PCR, immunoblot and/or ELISA. NF-κB transcriptional activity and promoter binding were monitored by luciferase-based promoter-reporter and ChIP assays, respectively. Interleukin (IL)-8 inhibition was achieved by gene silencing or neutralising-antibody treatment.

Results:

FKBP51 silencing reduced melanoma growth, metastasis, angiogenesis and neutrophil infiltration and led to IL-8 downregulation through NF-κB suppression in cell lines and tumour xenografts. IL-8 inhibition drastically decreased growth, migration and invasiveness of FKPB51-overexpressing cells; whereas its treatment partially restored the suppressed phenotypes of FKBP51-silenced melanoma cells. Interleukin-8 depletion in conditioned medium (CM) of FKBP51-overexpressing melanoma cells inhibited endothelial cell proliferation and capillary-like structure formation, whereas its treatment promoted these effects in endothelial cells cultured in CM of FKBP51-silenced melanoma cells.

Conclusions:

FKBP51 promotes melanoma growth, metastasis and angiogenesis, and IL-8 plays a key role in these processes. Thus, targeting of FKBP51 or its upstream or downstream regulatory pathways could lead to effective therapeutic strategies against melanoma.

Differences in transport mechanisms of trans-1-amino-3-[18F]fluorocyclobutanecarboxylic acid in inflammation, prostate cancer, and glioma cells: comparison with L-[methyl-11C]methionine and 2-deoxy-2-[18F]fluoro-D-glucose

PURPOSE

We aimed to elucidate trans-1-amino-3-[(18)F]fluorocyclobutanecarboxylic acid (anti-[(18)F]FACBC) uptake mechanisms in inflammatory and tumor cells, in comparison with those of L-[methyl-(11)C]methionine ([(11)C]Met) and 2-deoxy-2-[(18)F]fluoro-D-glucose ([(18)F]FDG).

PROCEDURES

Using carbon-14-labeled tracers, in vitro time-course, pH dependence, and competitive inhibition uptake experiments were performed in rat inflammatory (T cells, B cells, granulocytes, macrophages), prostate cancer (MLLB2), and glioma (C6) cells.

RESULTS

Anti-[(14)C]FACBC uptake ratios of T/B cells to tumor cells were comparable, while those of granulocytes/macrophages to tumor cells were lower than those for [(14)C]FDG. Over half of anti-[(14)C]FACBC uptake by T/B and tumor cells was mediated by Na(+)-dependent amino acid transporters (system ASC), whereas most [(14)C]Met transport in all cells was mediated by Na(+)-independent carriers (system L).

CONCLUSIONS

The low anti-[(18)F]FACBC accumulation in granulocytes/macrophages may be advantageous in discriminating inflamed regions from tumors. The significant anti-[(18)F]FACBC uptake in T/B cells may cause false-positives in some cancer patients who undergo FACBC-positron emission tomography (PET).

Macrophages, Neutrophils, and Cancer: A Double Edged Sword

The tumor microenvironment is a well-recognized framework, in which myeloid cells play important roles in cancer development from tumor initiation to metastasis. Immune cells present in the tumor microenvironment can promote or inhibit cancer formation and development. Diversity and plasticity are hallmarks of cells of the monocyte-macrophage lineage. In response to distinct signals the cells of the monocyte-macrophage lineage have the ability to display a wide spectrum of activation states; classical Ml or alternative M2 macrophages represent extremes of a continuum of this activation. Tumor-associated macrophages generally acquire an M2-like phenotype that is relevant for their participation in tumor growth and progression. There is now evidence that also neutrophils can be driven towards distinct phenotypes in response to microenvironmental signals. In fact they can interact with distinct cell populations and produce a wide number of cytokines and effector molecules. Therefore, macrophages and neutrophils are both integrated in the regulation of the innate and adaptive immune responses in various inflammatory situations, including cancer. These findings have triggered efforts to target tumor-associated macrophages and neutrophils. In particular, “reeducation” to activate their antitumor potential or elimination of tumor promoting cells is a new strategy undergoing preclinical and clinical evaluation.

The Multifaceted Roles Neutrophils Play in the Tumor Microenvironment

Neutrophils are myeloid cells that constitute 50-70 % of all white blood cells in the human circulation. Traditionally, neutrophils are viewed as the first line of defense against infections and as a major component of the inflammatory process. In addition, accumulating evidence suggest that neutrophils may also play a key role in multiple aspects of cancer biology. The possible involvement of neutrophils in cancer prevention and promotion was already suggested more than half a century ago, however, despite being the major component of the immune system, their contribution has often been overshadowed by other immune components such as lymphocytes and macrophages. Neutrophils seem to have conflicting functions in cancer and can be classified into anti-tumor (N1) and pro-tumor (N2) sub-populations. The aim of this review is to discuss the varying nature of neutrophil function in the cancer microenvironment with a specific emphasis on the mechanisms that regulate neutrophil mobilization, recruitment and activation.

Delayed apoptosis of tumor associated neutrophils in the absence of endogenous IFN-β

The importance of neutrophils in tumor immune surveillance, invasive growth and angiogenesis becomes increasingly clear. Many of neutrophil activities are controlled by endogenous IFN-β. Here, we provide evidence that endogenous IFN-β is regulating the apoptosis of pro-angiogenic tumor infiltrating neutrophils by influencing both, the extrinsic as well as the intrinsic apoptosis pathways. Accordingly, the life span of tumor associated neutrophils (TANs) is remarkably prolonged in tumor bearing Ifnb1(-/-) mice compared to wild type controls. Lower expression of Fas, reactive oxygen species, active Caspase 3 and 9, as well as a change in expression pattern of proapoptotic and antiapoptotic members of the Bcl-2 family and the major apoptosome constituent Apaf-1 is observed under such conditions. In line with inhibition of apoptosis and the prolonged neutrophil survival, in the absence of endogenous IFN-β, a strong enhancement of G-CSF expression and PI3 Kinase phosphorylation is detected. These data explain the increased longevity of tumor infiltrating neutrophils and the accumulation of such cells in tumors. Taken together, our findings add to the important role of Type I IFN in immune surveillance against cancer.

Subtypes of white blood cells in patients with prostate cancer or benign prostatic hyperplasia and healthy individuals

BACKGROUND

This study aimed to evaluate the baseline white blood cell (WBC), neutrophil, lymphocyte, monocyte, basophil, eosinophil count, total prostate-specific antigen (TPSA), free PSA (FPSA) level, neutrophil- to-lymphocyte and neutrophil-to-monocyte ratios among patients with prostate cancer and benign prostatic hyperplasia (BPH), as well as healthy individuals.

MATERIALS AND METHODS

2005-2012 laboratory files of 160 patients with prostate cancer at Kayseri Training and Research Hospital, Oncology Outpatient Clinic, 285 patients who were pathologically diagnosed with BPH in Urology Outpatient Clinic and 200 healthy individuals who were admitted to Internal Medicine Outpatient Clinic were retrospectively analyzed. Baseline WBC, neutrophil, lymphocyte, monocyte, basophil, eosinophil count, TPSA, FPSA level, neutrophil-to-lymphocyte ratio and neutrophil-to-monocyte ratio were recorded and compared across groups.

RESULTS

Patients with prostate cancer had a lower lymphocyte level compared to the patients with BPH and healthy controls (p<0.001). The mean monocyte count, leukocyte-to-monocyte ratio, and leukocyte-to-lymphocyte ratio were higher in patients with prostate cancer, but without significance. The mean WBC and leukocyte count were lower in patients with prostate cancer, but again without statistical significance (p=0.130). The mean TPSA and FPSA were 39.4 and 5.67, respectively in patients with prostate cancer, while they were 5.78 and 1.28 in patients with BPH. There was a significant difference in the mean TPSA and FPSA levels between the patient groups (p<0.001).

CONCLUSIONS

Our study results showed that patients with prostate cancer had a lower level of lymphocytes, neutrophils and WBCs and a higher level of monocytes with a significant difference in lymphocyte count, compared to healthy controls. We suggest that lymphocyte count may be used in combination with other parameters in the diagnosis of prostate cancer, thanks to its ease of assessment.

The role of inflammation in brain cancer

Malignant brain tumors are among the most lethal of human tumors, with limited treatment options currently available. A complex array of recurrent genetic and epigenetic changes has been observed in gliomas that collectively result in derangements of common cell signaling pathways controlling cell survival, proliferation, and invasion. One important determinant of gene expression is DNA methylation status, and emerging studies have revealed the importance of a recently identified demethylation pathway involving 5-hydroxymethylcytosine (5hmC). Diminished levels of the modified base 5hmC is a uniform finding in glioma cell lines and patient samples, suggesting a common defect in epigenetic reprogramming. Within the tumor microenvironment, infiltrating immune cells increase oxidative DNA damage, likely promoting both genetic and epigenetic changes that occur during glioma evolution. In this environment, glioma cells are selected that utilize multiple metabolic changes, including changes in the metabolism of the amino acids glutamate, tryptophan, and arginine. Whereas altered metabolism can promote the destruction of normal tissues, glioma cells exploit these changes to promote tumor cell survival and to suppress adaptive immune responses. Further understanding of these metabolic changes could reveal new strategies that would selectively disadvantage tumor cells and redirect host antitumor responses toward eradication of these lethal tumors.

Neutrophils promote the malignant glioma phenotype through S100A4

PURPOSE

Antiangiogenic therapy is effective in blocking vascular permeability, inhibiting vascular proliferation, and slowing tumor growth, but studies in multiple cancer types have shown that tumors eventually acquire resistance to blockade of blood vessel growth. Currently, the mechanisms by which this resistance occurs are not well understood.

EXPERIMENTAL DESIGN

In this study, we evaluated the effects of neutrophils on glioma biology both in vitro and in vivo and determined target genes by which neutrophils promote the malignant glioma phenotype during anti-VEGF therapy.

RESULTS

We found that an increase in neutrophil infiltration into tumors is significantly correlated with glioma grade and in glioblastoma with acquired resistance to anti-VEGF therapy. Our data demonstrate that neutrophils and their condition media increased the proliferation rate of glioblastoma-initiating cells (GIC). In addition, neutrophils significantly increased GICs Transwell migration compared with controls. Consistent with this behavior, coculture with neutrophils promoted GICs to adopt morphologic and gene expression changes consistent with a mesenchymal signature. Neutrophil-promoting tumor progression could be blocked by S100A4 downregulation in vitro and in vivo. Furthermore, S100A4 depletion increased the effectiveness of anti-VEGF therapy in glioma.

CONCLUSIONS

Collectively, these data suggest that increased recruitment of neutrophils during anti-VEGF therapy promotes glioma progression and may promote treatment resistance. Tumor progression with mesenchymal characteristics is partly mediated by S100A4, the expression of which is increased by neutrophil infiltration. Targeting granulocytes and S100A4 may be effective approaches to inhibit the glioma malignant phenotype and diminish antiangiogenic therapy resistance.

Tumor associated macrophages and neutrophils in tumor progression

Tumor-associated macrophages (TAMs) are a key component of the tumor microenvironment and orchestrate various aspects of cancer. Diversity and plasticity are hallmarks of cells of the monocyte-macrophage lineage. In response to distinct signals macrophages undergo M1 (classical) or M2 (alternative) activation, which represent extremes of a continuum in a spectrum of activation states. Metabolic adaptation is a key component of macrophage plasticity and polarization, instrumental to their function in homeostasis, immunity and inflammation. Generally, TAMs acquire an M2-like phenotype that plays important roles in many aspects of tumor growth and progression. There is now evidence that also neutrophils can be driven towards distinct phenotypes in response to microenvironmental signals. The identification of mechanisms and molecules associated with macrophage and neutrophil plasticity and polarized activation provides a basis for new diagnostic and therapeutic strategies.