CNSC-75. PROMINENT GLIOMA CALCIUM TRANSIENTS CAN BE REPEATEDLY TRIGGERED BY STIMULUS-EVOKED NEURONAL ACTIVITY AND PURINERGIC SIGNALING

Abstract Gliomas are aggressive primary brain tumors characterized by diffuse infiltration into surrounding brain tissue and interaction with non-neoplastic cells, including neurons. Excitatory neuronal activity is increasingly recognized as a driver of glioma progression, yet the underlying molecular mechanisms remain poorly understood. In particular, the effects of endogenous neuronal activity—both spontaneous and stimulus-evoked—on glioma cells are understudied. Using a mouse model in which glioma cells expressing the genetically encoded calcium indicator GCaMP6s infiltrate the somatosensory cortex, we performed in vivo two-photon imaging and found that whisker stimulation elicits robust calcium transients in glioma cells. To assess the spatial and temporal relationship between neuronal and glioma activity, we used dual-color wide-field optical mapping (WFOM) to simultaneously image neuronal and glioma calcium dynamics during tumor progression. We conducted these experiments in awake, behaving Thy1-jRGECO1a mice, which express a red calcium indicator in excitatory neurons and were implanted with GCaMP6s-expressing glioma cells near the somatosensory cortex. We recorded both resting-state and stimulus-evoked activity during whisker stimulation to examine how sensory-evoked neuronal activity influences glioma calcium signaling. Dual-color WFOM revealed large-scale glioma calcium transients triggered by whisker stimulation and spontaneous or evoked motor activity. These glioma calcium transients were preceded by, and highly correlated with, neuronal activity—and extended throughout the tumor even into regions where neuronal activity was abnormal or attenuated—suggesting involvement of extrasynaptic signaling. Because neuronal activity is known to cause extracellular release of ATP, and glioma cells express the purinergic receptor P2RX7, we investigated the effects of purinergic signaling on glioma calcium activity. In vitro, GCaMP6s-expressing glioma cells exhibited dose-dependent calcium responses to ATP that were attenuated by the purinergic inhibitor PPADS. Collectively, these findings demonstrate that stimulus-evoked neuronal activity can repeatedly trigger prominent glioma calcium transients and identify purinergic signaling as a potentially targetable mechanism of neuron-glioma crosstalk.