ABSTRACT
Glioblastoma is the most lethal tumor of the central nervous system, presenting a very poor prognostic, with a survival around 16 months. The interaction of mesenchymal stem cells and tumor cells has been studied, showing a bias in their role favoring or going against aggressiveness. Natural products such as flavonoids have showed their anticancer properties and the synergic potential with the activation of microenvironment cells to inhibit tumor progression. Agathisflavone is a flavonoid studied in neurodegenerative diseases and cancer. The present study investigated the effect of flavonoid in the viability of heterogeneous glioblastoma (GBM) cells considering a coculture or conditioned medium of mesenchymal stem cells (MSCs) effect, as well as the dose-dependent effect of this flavonoid in tumor migration and differentiation via STAT3. Agathisflavone (3-10 µM) induced dose-dependent toxicity to GL-15 and U373 human GBM cells, since 24 h after treatments. It was not toxic to human MSC but modified the pattern of interaction with GBM cells. Agathisflavone also inhibited migration and increased differentiation of human GBM cells, associated with the reduction on the expression of STAT3. These results demonstrate that the flavonoid agathisflavone had a direct anti-glioma effect. However, could be observed its effect in MSCs response that may have an impact in controlling GBM growth and aggressiveness, an important factor to consider for new therapies.
Subject(s)
Antineoplastic Agents/pharmacology , Biflavonoids/pharmacology , Brain Neoplasms/drug therapy , Glioblastoma/drug therapy , Mesenchymal Stem Cells/metabolism , Brain Neoplasms/pathology , Cell Differentiation/drug effects , Cell Line, Tumor , Cell Movement/drug effects , Cell Proliferation/drug effects , Cell Survival/drug effects , Coculture Techniques , Culture Media, Conditioned/pharmacology , Glioblastoma/pathology , Humans , STAT3 Transcription Factor/metabolismABSTRACT
BACKGROUND: A glioblastoma is a primary CNS tumor that is more aggressive and lethal than other brain tumors. Its location, rapid proliferation, invasive growth, angiogenesis and immunosuppression are the main factors that limit its treatment, making it a major challenge to neuro-oncology. OBJECTIVE: This study investigated the in vitro effects of the alkaloid dihydrochelerythrine (DHC), which is extracted from Zanthoxylum stelligerum, on the viability, proliferation, cell death and ß-catenin, NFκB, STAT3/pSTAT3 and interleukins roles. METHOD: In vitro experimental models of human (U251 and GL-15) and murine (C6) glioblastoma cells were cultured in the presence of DHC at increasing concentrations for MTT assay and exclusion trypan blue dye to determine EC50. Afterward, C6 and U251 cells were treated with 100 µM DHC or DMSO 0.1% for cell cycle, annexin and expression of ß-catenin/NFκB/STAT3/pSTAT3 by flow cytometry or immunofluorescence. Interleukin quantification was made by Cytometric Bead Array. RESULTS: A significant decrease was observed in C6 and U251 cell viability in a time and dose-dependent manner. GL-15 cell viability decreased only when treated with 200 µM DHC. This maximum concentration affected neither astrocytes nor microglia viability. A cytostatic effect of DHC was observed in C6 and U251 cells after 48 h of 100 µM DHC treatment. After 72 h of DHC treatment, C6 presented 80% of annexin-V+ cells compared to 10% of annexin-V+ U251 cells. C6 cells demonstrated significant high levels of NFκ B and ß-catenin cytoplasmic fraction. Additionally, DHC treatment resulted in higher significant levels of IL-6 than did other interleukins and STAT3 up-regulation in U251 cells. CONCLUSION: These results demonstrate that DHC acts as a chemosensitizing agent selective for glioma cells not affecting non-tumor cells. Considering tumor heterogeneity, DHC demonstrated an anti-cancer potential to activate different cell death pathways. DHC demonstrated could be used for chemotherapy and immunotherapy applications in glioblastomas in the future.
