INCREASED INVASION OF GLIOMA CANCER STEM CELLS UNDER C5 alpha FROM GLIOMA STROMA MESENCHYMAL STEM-LIKE CELLS BY MEANS OF pp38 NETWORKING

Abstract

The presence of glioma stroma mesenchymal stem-like cells (GS-MSLCs) from Korean glioma patients has been recently reported. How these cells function as a part of the glioma microenvironment, however, remains incompletely understood. Here, we investigated the biological effects of GS-MSLCs on glioma cancer stem cells (gCSCs), testing the hypothesis that GS-MSLCs alter the biological characteristics of gCSCs. gCSCs were cultured alone and co-cultured with GS-MSLCs or bone marrow mesenchymal stem cells (BM-MSCs). Glioneural differentiation, stemness, invasion, epithelial mesenchymal transition (EMT), and cytokine assay, were compared between the three groups (gCSCs alone vs. gCSCs with GS-MSLCs vs. gCSCs with BM-MSCs). Next, three groups of orthotopic xenografts in mice were created. Then tumor size, survival, and invasion extent were examined using immunohistochemical analyses. When we co-cultured gCSCs with GS-MSLCs, increased glioneural differentiation (increased Olig2, GFAP, and Tuj1), decreased stemness (decreased CD133, nestin, Sox2, notch2), and increased invasion/EMT (zeb1, β-catenin and N-cadherin). However there were no increased invasion/EMT with gCSCs alone group or gCSCs co-cultured with BM-MSCs group. According to cytokine assay, we found 7 cytokines (C5α, GROα, IL-6, IL-8, MCP1, MIF, PAI-1) from GS-MSLCs. Among them, C5α from GS-MSLCs may be related with increased invasion/EMT of gCSCs through siRNA study. In functional study, we finally found C5 and pp38 were key signal networking molecules. Mice co-injected with gCSCs and GS-MSLCs had significantly larger tumor size, and shorter survival then control groups. Immunohistochemical analysis showed increased glioma invasion/ EMT related expression (zeb1). We have successfully proved the biological effect of human GS-MSLCs on human gCSCs. GS-MSLCs can differentiate gCSCs into neuro-glial cells and enhance invasion by C5α and pp38. Our results indicated that GS-MSLCs may influence the biological properties of gCSCs, shifting them towards a more aggressive status. GS-MSLCs could be a new target cells for the treatment of glioma in the future.