gms | German Medical Science

Objective: The cellular microenvironment of glioblastoma multiforme is rarely explored and its biological meaning for tumor development and malignancy is widely unknown. In this study we aimed to investigate regulatory functions of astrocytes in the microenvironment of glioblastoma multiforme.

Methods: Patient-derived primary cell lines (n=3) and an established astrocytic cell line were infected by lentiviral particles (pLV_zgreen, pLV_mcherry). Cells were cultured in monocultures as well as co-cultures and separated by FACS after 48h. Transcriptome was analyzed by mRNA sequencing and validated by qRT-PCR. Cell behavior analysis was performed by a 3D migration assay and invasion assay. Resistance to hypoxia and chemotherapy was validated by a cell viability assay. Additionally, metabolic profiling of mono-/co-cultured media was performed (NMR) followed by comprehensive bioinformatical and integrative analysis.

Results: Transcriptional profiling of tumor cells in an astrocytic environment showed a significant up-regulation of neural differentiation. Metabolic analysis of the medium uncovered an increased intensity of GABA after 48h co-culture. Moreover, tumor cells were found to up-regulate the GABAA receptor in an astrocyte environment and patch-clamp experiments revealed an increased activity of tumor cells in an astrocytic environment. Tumor cell proliferation and neural-like differentiation were shown to be dependent on the astrocyte/tumor ratio. Nevertheless, the co-cultured tumor showed an increased resistance to hypoxia and chemotherapy (TMZ).

Conclusion: This study reports a novel role of astrocytes in the tumor environment. The regulatory functions were influenced by the amount of tumor in an astrocyte environment. Astrocyte-tumor interaction led to increased neural differentiation but drove tumor resistance to hypoxic conditions and chemotherapy. This novel regulatory function of astrocytes opens new prospects for therapeutic targets in the future.