Accumulating evidence indicates that myeloid cells are critically involved in the pathophysiology of human cancers. In contrast to the well-characterized tumor-associated macrophages, the significance of granulocytes in cancer has only recently begun to emerge. A number of studies found increased numbers of neutrophil granulocytes and granulocytic myeloid-derived suppressor cells (GrMDSCs) both in the peripheral blood and in the tumor tissues of patients with different types of cancer. Most importantly, granulocytes have been linked to poor clinical outcome in cancer patients which suggests that these cells might have important tumor-promoting effects. In this review, we will address in detail the following major topics: (1) neutrophils and GrMDSCs in the peripheral blood of cancer patients-phenotype and functional changes; (2) neutrophils and GrMDSCs in the tumor tissue-potential mechanisms of tumor progression and (3) relevance of neutrophils and GrMDSCs for the clinical outcome of cancer patients. Furthermore, we will discuss the advantages and disadvantages of the current strategies used for identification and monitoring of human MDSCs. We propose a six-color immunophenotyping protocol that discriminates between monocytic MDSCs (MoMDSCs), two subsets of GrMDSCs and two subsets of immature myeloid cells in human cancer patients, thus, allowing for an improved characterization and understanding of these multifaceted cells.

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The progression of epithelial cancer is associated with an intense immunological interaction between the tumor cells and immune cells of the host. However, little is known about the interaction between tumor cells and polymorphonuclear granulocytes (PMNs) in patients with head and neck squamous cell carcinoma (HNSCC). In our study, we investigated systemic PMN-related alterations in HNSCC, the role of tumor-infiltrating PMNs and their modulation by the tumor microenvironment.We assessed the infiltration of HNSCC tissue by PMNs (retrospectively) and systemic PMN-related alterations in blood values (prospectively) in HNSCC patients (n 5 99 and 114, respectively) and control subjects (n 5 41). PMN recruitment, apoptosis and inflammatory activity were investigated in an in vitro system of peripheral blood PMNs and a human HNSCC cell line (FaDu). HNSCC tissue exhibited considerable infiltration by PMNs, and strong infiltration was associated with poorer survival in advanced disease. PMN count, neutrophil-to-lymphocyte ratio and serum concentrations of CXCL8 (interleukin-8), CCL4 (MIP-1b) and CCL5 (RANTES) were significantly higher in the peripheral blood of HNSCC patients than in that of controls. In vitro, HNSCC-conditioned medium inhibited apoptosis of PMNs, increased chemokinesis and chemotaxis of PMNs, induced release of lactoferrin and matrix metalloproteinase 9 by PMNs and enhanced the secretion of CCL4 by PMN. Our findings demonstrate alterations in PMN biology in HNSCC patients. In vitro, tumor-derived factors modulate cellular functions of PMNs and increase their inflammatory activity. Thus, the interaction between HNSCC and PMNs may contribute to host-mediated changes in the tumor microenvironment.Worldwide, head and neck cancer is one of the six most common cancers. More than 90% of head and neck cancers are squamous cell carcinomas (HNSCCs) that primarily originate in the oral cavity, the pharynx and the larynx. [1][2][3] HNSCCs display an inflammatory microenvironment with frequent infiltration by large numbers of immune cells. This infiltration results in a reciprocal interaction between the malignant tissue and the immune cells that causes local and systemic alterations, often resulting in the downregulation of immune functions and the tumor escape from immune control. [4][5][6] Accumulating evidence suggests that polymorphonuclear granulocytes (PMNs) and other myeloid cells play an important tumor-promoting role during tumor progression. 7-9 High numbers of PMNs before treatment, as determined in the peripheral blood of patients with malignant melanoma, 10 and an increased neutrophil-to-lymphocyte ratio (NLR), as demonstrated in ovarian cancer, 11 have been proposed as independent prognostic factors for short overall survival. Tumor-infiltrating PMNs have been linked to a poorer prognosis for patients with lung adenocarcinoma of the bronchioloalveolar subtype, 12 but they seem to be associated with a reduced mortality for patients with gastric carcinoma. 13 PMN functions are modulated by a variety of ...

We have previously shown that activation of the acid sphingomyelinase (ASM), the release of ceramide and the formation of ceramide-enriched membrane domains are central for the induction of apoptosis by CD95. Here, we demonstrate that tumor necrosis factor-related apoptosisinducing ligand (TRAIL) and CD95 activate the ASM via a redox mechanism resulting in release of ceramide and formation of ceramide-enriched membrane platforms. Ceramide-enriched membrane platforms serve to cluster DR5 upon stimulation. Antioxidants prevent TRAILmediated stimulation of ASM, the release of ceramide, the formation of ceramide-enriched membrane platforms and the induction of apoptosis by TRAIL. Further, ASMdeficient splenocytes fail to cluster DR5 in ceramideenriched membrane domains upon TRAIL stimulation and resist TRAIL-induced apoptosis, events that were restored by addition of natural C 16 -ceramide. A dose-response analysis indicates that ceramide-enriched membrane platforms greatly sensitized tumor cells to TRAIL-induced apoptosis. Our data indicate that ceramide-enriched membrane platforms are required for the signaling of TRAIL-DR5 complexes under physiological conditions.

Macrophage migration inhibitory factor (MIF) is an inflammatory cytokine that has been reported to enhance the aggressiveness and metastatic potential of tumor cells. However, the mechanisms through which MIF influences tumor development and progression are not understood. The objectives of our study were to assess the effects of tumor-derived MIF on neutrophils in head and neck cancer (HNC) and to identify possible feedback effects on tumor cells. To this end, we used an in vitro system to model the interaction between human HNC cells and neutrophils. In addition, we analyzed expression of MIF in tissues from HNC patients in relation to neutrophilic infiltration and clinical parameters. Our results show that human HNC is infiltrated by neutrophils proportional to the levels of tumoral MIF. Strong MIF expression by the tumor is associated with higher lymph node metastasis and reduced survival in HNC patients. In vitro, MIF modulated functions of human neutrophils by inducing chemokine CXC motif receptor 2(CXCR2)-dependent chemotaxis, enhancing neutrophil survival and promoting release of chemokine C-C Motif Ligand 4 (CCL4) and matrix metalloprotease 9(MMP9). Further, neutrophils activated with tumor-derived MIF enhanced migratory properties of HNC cells. In conclusion, our data indicate that the effects of tumor-derived MIF on neutrophils represent an additional mechanism by which MIF might contribute to tumor progression.

Neutrophils are primary inflammatory cells and absolutely essential to protect the host during the early phases of microbial infection. Their role in cancer is less clear. Current evidence suggests that neutrophils show high functional plasticity and can adopt protumor and antitumor activity. Protumor neutrophils are functionally related to the recently described granulocytic myeloid-derived suppressor cells. We propose a model in which homeostatic chronic recruitment and activation of neutrophils result in mainly protumor activity. In contrast, therapeutic interventions in many cases elicit acute activation, enhance direct effector functions as well as indirect regulatory functions of neutrophils with potent antitumor activity. Conversion of protumor activity of neutrophils into antitumor activity by means of appropriate stimulation or modulation may offer new possibilities in biologic therapy of cancer.

Solid tumors such as head and neck squamous cell carcinoma (UNSee) display an intense interaction between tumoral factors and the immune system. Functional modulation of tumor-infiltrating and peripheral blood immune cells plays an important role during tumor progression. In this pilot study we compared biological functions of polymorphonuclear granulocytes (PMN) from the peripheral blood of UNSee patients and healthy subjects. PMN were simultaneously isolated from the peripheral blood of UNSee patients and healthy donors for functional analysis (apoptosis, production of reactive oxygen species (ROS), cytokine release and immunophenotyping). PMN from UNSee patients showed a significantly lower inducible production of ROS (P = 0.02) and reduced spontaneous apoptosis (P = 0.008) compared with PMN from healthy donors. Under standard culture conditions, there was no significant difference regarding the release of inflammatory cytokines between PMN from UNSee patients and PMN from healthy donors. Confirming previous observations, serum concentrations of PMN-related cytokines were significantly higher in the peripheral blood of UNSee patients than in that of controls. Importantly, immunophenotyping revealed an increased number of immature PMN in PMN fractions isolated from UNSee patients. Peripheral blood PMN from UNSee patients and healthy donors show distinct functional differences. The presence of increased numbers of immature stages of PMN in UNSee patients may partly contribute to the changes observed. After recruitment to and infiltration of the tumor, PMN may be further modulated in the local tumor microenvironment. This pilot study justifies functional analyses of myeloid cells in larger cohorts of patients with UNSee.Cancer-related inflammation in solid tumors is associated with modulation of immune cells finally resulting in tumor progression (I). Head and neck squamous cell carcinoma (HNSCC) displays frequent infiltration by various immune effector cells and reciprocal interaction between tumor and immune cells. This interaction leads to an increased local and systemic expression of immune-modulating mediators, often resulting in immuno-suppression and the escape of the tumor from immune control (2). Accumulating evidence suggests that polymorphonuclear granulocytes (PMN, neutrophils) and other myeloid cells play an important tumor-promoting role during tumor progression (3-4). In the tumor host, tumor-derived factors modulate PMN functions: For instance, in bronchioalveolar carcinoma, production of antiapoptotic factors by the tumor

The carbonic anhydrases (CAs) constitute a family of almost ubiquitous enzymes of significant importance for many physiological and pathological processes. CAs reversely catalyse the conversion of CO(2) + H(2)O to HCO(3) (-) and H(+), thereby contributing to the regulation of intracellular pH. Above all, CAs are of key importance for cells that perform glycolysis that inevitably leads to the intracellular accumulation of lactate. CA XII is a plasma membrane-associated isoform of the enzyme, which is induced by hypoxia and oestrogen and, consequently, expressed at high levels on various types of cancer and, intriguingly, on cancer stem cells. The enzyme is directly involved in tumour progression, and its inhibition has an anti-tumour effect. Apart from its role in carcinogenesis, the enzyme contributes to various other diseases like glaucoma and arteriosclerotic plaques, among others. CA XII is therefore regarded as promising target for specific therapies. We have now generated the first monoclonal antibody (6A10) that binds to the catalytic domain of CA XII on vital tumour cells and inhibits CA XII enzyme activity at nanomolar concentrations and thus much more effective than acetazolamide. In vitro results demonstrate that inhibition of CA XII by 6A10 inhibits the growth of tumour cells in 3-dimensional structures. In conclusion, we generated the first specific and efficient biological inhibitor of tumour-associated CA XII. This antibody may serve as a valuable tool for in vivo diagnosis and adjuvant treatment of different types of cancer.