Macrophage Colony-Stimulating Factor as a Tumor Marker for Squamous Cell Carcinoma of the Head and Neck

CSF-1R in Cancer: More than a Myeloid Cell Receptor

Colony-stimulating factor 1 receptor (CFS-1R) is a myeloid receptor with a crucial role in monocyte survival and differentiation. Its overexpression is associated with aggressive tumors characterized by an immunosuppressive microenvironment and poor prognosis. CSF-1R ligands, IL-34 and M-CSF, are produced by many cells in the tumor microenvironment (TME), suggesting a key role for the receptor in the crosstalk between tumor, immune and stromal cells in the TME. Recently, CSF-1R expression was reported in the cell membrane of the cancer cells of different solid tumors, capturing the interest of various research groups interested in investigating the role of this receptor in non-myeloid cells. This review summarizes the current data available on the expression and activity of CSF-1R in different tumor types. Notably, CSF-1R+ cancer cells have been shown to produce CSF-1R ligands, indicating that CSF-1R signaling is positively regulated in an autocrine manner in cancer cells. Recent research demonstrated that CSF-1R signaling enhances cell transformation by supporting tumor cell proliferation, invasion, stemness and drug resistance. In addition, this review covers recent therapeutic strategies, including monoclonal antibodies and small-molecule inhibitors, targeting the CSF-1R and designed to block the pro-oncogenic role of CSF-1R in cancer cells.

Self-Renewal of Macrophages: Tumor-Released Factors and Signaling Pathways

Macrophages are the most abundant immune cells of the tumor microenvironment (TME) and have multiple important functions in cancer. During tumor growth, both tissue-resident macrophages and newly recruited monocyte-derived macrophages can give rise to tumor-associated macrophages (TAMs), which have been associated with poor prognosis in most cancers. Compelling evidence indicate that the high degree of plasticity of macrophages and their ability to self-renew majorly impact tumor progression and resistance to therapy. In addition, the microenvironmental factors largely affect the metabolism of macrophages and may have a major influence on TAMs proliferation and subsets functions. Thus, understanding the signaling pathways regulating TAMs self-renewal capacity may help to identify promising targets for the development of novel anticancer agents. In this review, we focus on the environmental factors that promote the capacity of macrophages to self-renew and the molecular mechanisms that govern TAMs proliferation. We also highlight the impact of tumor-derived factors on macrophages metabolism and how distinct metabolic pathways affect macrophage self-renewal.

Small-Molecule CSF1R Inhibitors as Anticancer Agents

Persuasive evidence has been presented linking the infiltration of Tumor-Associated Macrophages (TAMs) with the driving force of tumorigenesis and in the suppression of antitumor immunity. In this context CSF1R, the cellular receptor for Colony Stimulating Factor-1 (CSF1) and Interleukin 34 (IL-34), occupies a central role in manipulating the behavior of TAMs and the dysregulation of CSF1R signaling has been implicated in cancer progression and immunosuppression in many specific cancers. Consequently, CSF1R kinase has been a target of great interest in cancer treatment and significant research efforts have focused on the development of smallmolecule CSF1R inhibitors. In this review, we highlight current progress on the development of these small molecule CSF1R inhibitors as anticancer agents. Special attention is paid to the compounds available in advanced clinical trials.

Targeting tumor-associated macrophages in head and neck squamous cell carcinoma

In head and neck squamous cell carcinoma (HNSCC), tumor-associated macrophages (TAMs) are associated with a poorer prognosis. TAMs, derived from inflammatory monocyte, play a critical role in regulating tumor progression. Generally, TAMs promote tumor progression and suppress immune response via both innate and adaptive immune mechanisms. However, as the double-blade sword, TAMs retain the potential pro-inflammatory ability to inhibit tumor progression. By depleting the immunosuppressive function or evoking anti-tumor ability, therapeutic strategies targeting TAMs show promising preclinical and clinical effects. Now, macrophage-centered therapeutic approaches are entering the clinical arena. In this review, we discuss the immunosuppressive role of TAMs in the tumor microenvironment and the therapeutic approaches targeting macrophages which offer promise in improving HNSCC outcome.

Colony stimulating factor-1 receptor promotes proliferation, migration and invasion in the human nasopharyngeal carcinoma 6-10B cell line via the phosphoinositide 3-kinase/Akt pathway

The present study aimed to investigate the effects of colony-stimulating factor-1 receptor (CSF-1R) on proliferation, migration and invasion in the human nasopharyngeal carcinoma (NPC) 6-10B cell line, and to investigate the possible underlying mechanisms. Using a lentiviral transfection method, a virus carrying the CSF-1R gene was transfected into 6-10B cells. The expression of CSF-1R was then detected by reverse transcription-quantitative polymerase chain reaction and western blot analysis, and was revealed to be markedly enhanced in 6-10B cells. Subsequently, an MTT assay was performed to assess cell proliferative ability, and flow cytometric analysis was utilized to measure the apoptotic rate of the cells. Wound healing and Transwell assays were also performed to observe cell migration and invasion capabilities. Additionally, western blot analysis was used to detect the protein expression of the proliferation and apoptosis signaling factors cyclin D1, B-cell lymphoma 2, Bcl-2-associated X protein, and phosphorylated and total extracellular protein kinase B (Akt/PKB) in 6-10B cells. The results showed that CSF-1R overexpression promoted the proliferation, migration and invasion of the 6-10B cells. The corresponding mechanism may be associated with activation of the phosphoinositide 3-kinase/Akt pathway, which promotes cell survival and proliferation. These results indicated a potential molecular target for the treatment of NPC.

Oral health and pathology: a macrophage account

Macrophages are present in healthy oral mucosa and their numbers increase dramatically during disease. They can exhibit a diverse range of phenotypes characterised as a functional spectrum from pro-inflammatory to anti-inflammatory (regulatory) subsets. This review illustrates the role of these subsets in the oral inflammatory disease lichen planus, and the immunosuppressive disease oral squamous cell carcinoma (SCC). We conclude that the role of macrophages in driving progression in oral disease identifies them as potential therapeutic targets for a range of oral pathologies.

Clinical significance of serum cytokine measurements in untreated colorectal cancer patients: soluble tumor necrosis factor receptor type I--an independent prognostic factor

The aim of this study was to exploit the potential clinical use of circulating cytokine measurements in colorectal cancer (CRC) patients. The levels of cytokines and cytokine receptors were assessed by ELISA in the sera of 50 healthy volunteers and 157 patients with previously untreated CRC and then related to clinicopathological features and prognosis. All tumors were verified histologically as colorectal adenocarcinomas and staged according to TNM classification. The levels of circulating interleukin (IL)-6, IL-8, macrophage colony-stimulating factor (M-CSF) and interleukin 1 receptor antagonist (IL-1ra) significantly increased with the clinical stage of CRC, and the levels of IL-6, soluble tumor necrosis factor (sTNF) receptor type I (RI), soluble interleukin 2 receptor alpha and TNFalpha with tumor grade, while IL-6, IL-8, M-CSF, IL-1ra and sTNF RI levels significantly rose with bowel wall invasion. None of the cytokine or soluble cytokine receptor levels were influenced by age, gender and colon versus rectum localization. sTNF RI, IL-8, IL-6 and vascular endothelial growth factor measurements demonstrated the highest diagnostic sensitivity. sTNF RI was found elevated in the greatest percentage of all CRC patients, in the greatest proportion of stage I patients and presented the best diagnostic sensitivity. In addition, the sTNF RI level strongly correlated with tumor grade and invasion and proved to be an independent prognostic factor.