On the role of 25-hydroxycholesterol synthesis by glioblastoma cell lines. Implications for chemotactic monocyte recruitment

Abstract

Glioblastoma multiforme (GBM) is the most common malignant primary brain tumor and is invariably fatal to affected patients. Oxysterols belong to a class of bioactive lipids that are implicated in neurological disease and are associated with various types of cancer. Here, we investigated expression and transcriptional regulation of cholesterol 25-hydroxylase (CH25H) in human U87MG and GM133 glioblastoma cell lines. We demonstrate that in both cell lines transcription and translation of CH25H are increased in response to TNFα and IL1β. In parallel, both cell lines upregulate 25-hydroxycholesterol (25-OHC) synthesis and secretion to levels comparable to bone marrow-derived mouse macrophages under inflammatory conditions. To determine whether 25-OHC acts as chemoattractant for tumor-associated macrophages, the human THP-1 monoblastic leukemia cell line was treated with varying amounts of the oxysterol. Experiments revealed that 25-OHC and lipid extracts isolated from GM133-conditioned medium (containing 7-fold higher 25-OHC concentrations than U87MG medium) induce chemotactic migration of THP-1 cells. Of note, 25-OHC also induced the migration of primary human peripheral blood monocytes. In response to exogenously added 25-OHC, THP-1 cells reorganized intermediate filament-associated vimentin to more cortical and polarized structures. Chemotactic migration of monocytes in response to 25-OHC was pertussis toxin-sensitive, indicating the involvement of G protein-coupled receptors. Using RNA interference we demonstrated that G protein–coupled receptor 183 (EBI2) contributes to 25-OHC-mediated chemotactic migration of THP-1 cells. These in vitro data indicate that GBM-derived and secreted 25-OHC may be involved in the recruitment of immune-competent cells to a tumor via EBI2.

Immune and Stroma Related Genes in Breast Cancer: A Comprehensive Analysis of Tumor Microenvironment Based on the Cancer Genome Atlas (TCGA) Database

“…GPR183 mediated in immune response, intestinal immunity and inflammation (45) when activated in T cells, B cells, dendritic cells and macrophages (46)(47)(48). In glioblastoma multiforme, GPR183 contributed to chemotactic migration of THP-1 cells toward tumor (49). P2RY13, in another hand, was analyzed in lung adenocarcinoma and associated with survival of patients (50), which was similar to our analysis.…”

Cholesterol metabolism in cancer: mechanisms and therapeutic opportunities

“…Cancer cells secrete hyaluronic acid oligomers, thereby increasing cholesterol efflux in TAMs and directing TAMs towards an M2-like phenotype that accelerates tumour progression 82 . Moreover, 25HC interacts with G-protein-coupled receptor 183 and triggers migration of both macrophages and human blood monocytes by reorganizing the cytoskeletal protein vimentin 83 . In addition to these effects on TAMs, 25HC can advance gastric cancer cell metastasis by promoting matrix metallopeptidase expression, without affecting cell proliferation and apoptosis 84 .…”

Sphingosine-1-Phosphate in the Tumor Microenvironment: A Signaling Hub Regulating Cancer Hallmarks

“…In the U87MG cell line, the ABCA1 transporter, which facilitates S1P efflux in astrocytes, was found involved in the S1P efflux, thereby contributing to inside-out signaling [121]. ABCA1 expression in this GBM cell line is potently induced by 25-OH-cholesterol [121], a natural oxysterol synthesized and secreted by GBM cells [122], suggesting that oxysterol synthesis provides an autocrine signal that enhances ABCA1 expression and S1P export from GBM cells.…”