Importance of direct macrophage ‐ Tumor cell interaction on progression of human glioma

Abstract

We previously showed tumor-associated macrophages/microglia (TAMs) polarized to the M2 phenotype were significantly involved in tumor cell proliferation and poor clinical prognosis in patients with high grade gliomas. However, the detailed molecular mechanisms involved in the interaction between TAMs and tumor cells have been unclear. Current results reveal that, in coculture with human macrophages, BrdU incorporation was significantly elevated in glioma cells, and signal transducer and activator of transcription-3 (Stat3) activation was found in both cell types. Direct mixed coculture led to stronger Stat3 activation in tumor cells than did indirect separate coculture in Transwell chamber dishes. Screening with an array kit for phospho-receptor tyrosine kinases revealed that phosphorylation of macrophagecolony stimulating factor receptor (M-CSFR, CD115, or c-fms) is possibly involved in this cell-cell interaction; M-CSFR activation was detected in both cell types. Coculture-induced tumor cell activation was suppressed by siRNA-mediated downregulation of the M-CSFR in macrophages and by an inhibitor of M-CSFR (GW2580). Immunohistochemical analysis of phosphorylated (p) M-CSFR, pStat3, M-CSF, M2 ratio, and MIB-1(%) in high grade gliomas revealed that higher staining of pM-CSFR in tumor cells was significantly associated with higher M-CSF expression and higher MIB-1(%). Higher staining of pStat3 was associated with higher MIB-1(%). High M2 ratios were closely correlated with high MIB-1(%) and poor clinical prognosis. Targeting these molecules or deactivating M2 macrophages might be useful therapeutic strategies for high grade glioma patients. (Cancer Sci 2012; 103: 2165-2172

Selective depletion of cultured macrophages by magnetite nanoparticles modified with gelatin

“…M-CSFR inhibition abrogates glioma progression by inhibiting the pro-tumor activation of TAMs (25). Although there have been a number of research studies regarding M-CSF production from glioma cells (26)(27)(28), to the best of our knowledge, there is no published research assessing M-CSFR expression in glioma cells, other than a previous study that reported the activation of M-CSFR in both glioma cells and TAMs in human glioma samples (8). The observations indicated that M-CSFR expression in cultured glioma cell lines is markedly lower than that in macrophages, and may suggest that M-CSFR expression in glioma cells may not be of particular interest for further research.…”

“…It has been previously demonstrated that co-culture with macrophages induces activation of T98G cells; however, the gene expression profile of T98G cells was not evaluated (8). Therefore, in the present study, the gene expression of CCL2, IL-6, O(6)-methylguanine-DNA methyltansferase (MGMT), transforming growth factor-β (TGF-β), vascular endothelial growth factor-A (VEGF-A) and M-CSFR in control T98G cells and in the T98G cells isolated from a co-culture with macrophages was investigated by RT-qPCR.…”

“…Intracellular adhesion molecule-1 and membrane type macrophage-colony stimulating factor (M-CSF) are known to be involved in this direct cell-cell contact (7,8). It has previously been demonstrated that the growth of a number of tumor cells, including glioma and lymphoma cells, was upregulated by direct co-culture with macrophages, and that signal transducer and activator of transcription (STAT) 3 activation was involved in this tumor cell activation (9,10).…”

“…However, the significance of cell-cell contact between macrophages and tumor cells remains unknown. Previous studies attempted to separate macrophages from tumor cells following direct co-culture experiments; however, it proved too difficult to separate the two types of cells (8,11). Sorting methods using flow cytometry were not suitable for gene expression analysis because of RNA degradation during the procedure (11).…”

Probing the Bi-directional Interaction Between Microglia and Gliomas in a Tumor Microenvironment on a Microdevice

“…Therefore, little data is available to compare the phenotypes and behavior of microglia at tumor onset and during the late stage of glioma progression [28]. Similarly, it is difficult to observe the dynamic process of tumor invasion with the Transwell or Boyden chamber assay, an in vitro model that has recently been widely adopted in the study of glioma invasion and migration [10,29,30]. Compared to the Transwell assay, the obvious advantages of the newly developed microfluidic technology are the manufacture of chips in various forms to meet different experimental requirements and the ability to observe cellular behavior dynamically, temporally, and spatially in a controlled microenvironment [31].…”