Drosophila glioma models: a view from the neural stem cell niche.

Gliomas are the most common primary brain tumours in adults, characterised by significant cellular and molecular heterogeneity. Recent advances in molecular profiling have transformed brain tumour classification but, despite these developments, gliomas remain refractory to standard and targeted treatments. The prediction that glioma stem cells (GSCs) drive tumour initiation has focused research efforts on determining intrinsic mechanisms driving acquisition of stemness. Nevertheless, GSCs reside in a cellular environment (or stem cell niche) comprised of differentiated glioma cells, with potential to influence stemness of neighbouring GSCs. Thus, if we are to understand initiation and progression of these stem cell-driven tumours, in addition to elucidating cell intrinsic regulation of GSC fate, we must also delineate extrinsic signalling inputs from the GSC niche. For this, we require in vivo models enabling dissection of key lines of communication between GSCs and the surrounding niche. Here we provide an overview of GSC-niche modelling using Drosophila, where key mechanisms of neural stem cell control and genetic drivers of glioma are conserved. We focus on the utility of Drosophila models for modelling both intrinsic and extrinsic inputs to stem cell fate control, which have provided unique insights into the molecular and cellular basis of glioma initiation and progression.