Neuronal FSTL4 negatively regulates BDNF-mediated neuron-glioma interaction

Gliomas exploit various molecular pathways to promote their survival, proliferation, and invasion. Recent studies reveal the complex neuron-glioma interaction and BDNF plays a major role in this interaction. However, it's unclear whether and how the BDNF-mediated cross-talk between neurons and gliomas is regulated. FSTL4 is reported to negatively regulate BDNF maturation. Here, we hypothesized that neuronal FSTL4 may negatively regulate BDNF-mediated neuron-glioma cross-talk. By using a combination of approaches like chemogenetic activation of primary neurons and CRISPR knockout/activation of endogenous FSTL4, we show that activated primary neurons support the proliferation of co-cultured glioma cells and neuronal BDNF secretion mediates this neuron-glioma interaction via activating TrkB in glioma cells. In addition, this process is negatively regulated by neuronal FSTL4 as its CRISPR KO in primary neurons further supports the proliferation of co-cultured glioma cells. Importantly, CRISPR activation of endogenous FSTL4 expression in primary neurons results in impaired ability to support co-cultured glioma cells, highlighting the therapeutic potential of activating endogenous FSTL4 for glioma treatment. Taken together, our study shows that the FSTL4/BDNF/TrkB axis plays an essential role in fine-tuning the neuron-glioma interaction and targeting this interplay with CRISPR tools may help to develop novel therapeutic strategies.