Mechanisms of malignancy in glioblastoma cells are linked to MCU upregulation and higher intracellular calcium level.

Glioblastoma (GBM) is one of the most malignant brain tumours and, despite advances in treatment modalities, it remains largely incurable. Ca2+ regulation and dynamics play crucial roles in different aspects of cancer, but they have never been investigated in detail in GBM. Here, we report that spontaneous Ca2+ waves in GBM cells cause unusual intracellular Ca2+ ([Ca2+](i)) elevations (>1 mu M), often propagating through tumour microtubes (TMs) connecting adjacent cells. This unusual [Ca2+](i) elevation is not associated with the induction of cell death and is concomitant with overexpression of mitochondrial Ca2+ uniporter (MCU). We show that MCU silencing decreases proliferation and alters [Ca2+](i) dynamics in U87 GBM cells, while MCU overexpression increases [Ca2+](i) elevation in human astrocytes (HAs). These results suggest that changes in the expression level of MCU, a protein involved in intracellular Ca2+ regulation, influences GBM cell proliferation, contributing to GBM malignancy.