ME-14PRO-MIGRATORY AND -PROLIFERATIVE EFFECTS OF ASTROCYTES ON GBM CELLS.

Glioblastoma multiforme (GBM) is among the most lethal types of cancer. The pathological tissue contains different tumor-associated cell types, including astrocytes, which contribute to cancer biology. Our work aims at exploring the potential role(s) of crosstalk between astrocytes and malignant cells in GBM with regard to invasion, growth and drug response of the malignant cells. Studies are performed with the double intention of identifying the molecular details of such pathogenic paracrine cross-talk and to establish high-throughput assays for identification of novel candidate therapeutic agents. In order to look for astrocyte-dependent effects on glioblastoma cells proliferation and migration, we have performed co-culture experiments, including direct co-culture, transwell assays and conditioned medium assays. Interestingly, we identified consistent stimulatory effects of astrocytes on the migration and proliferation of glioblastoma cells. In a direct co-culture system where an initial amount of 1000 glioblastoma cells is seeded with or without astrocytes, glioblastoma cells grow much more in co-culture than monoculture. In a transwell assay some glioblastoma cells clearly increase their migration upon indirect contact with astrocytes (U87, A172, HF66), whereas others are minimally affected by the co-culture. A172 and HF66 increase their migration even more when cultured with astrocytes pre-stimulated with PDGF-BB. Preliminary results also indicate that the astrocyte-dependent stimulation of GBM proliferation is dependent on PDGFR-signaling in astrocytes and/or GBM cells. Additional studies are ongoing where a more in vivo-like assay - invasion of GBM cells into brain slices - is being applied. In this assay the role(s) of host factors is being explored by "priming" of brain slices with growth factors, such as TGF-beta and PDGF-BB, or inhibitors of these pathways. The co-culture- and brain slice-assays will also be used to explore if host cells, such as astrocytes, will modulate sensitivity to temozolomide which is the most commonly used drug for glioblastoma treatment.