Hexokinase 2 displacement from mitochondria-associated membranes prompts Ca2+-dependent death of cancer cells

Abstract

Cancer cells undergo changes in metabolic and survival pathways that increase their malignancy. Isoform 2 of the glycolytic enzyme hexokinase (HK2) enhances both glucose metabolism and resistance to death stimuli in many neoplastic cell types. Here we observe that HK2 locates at mitochondria-endoplasmic reticulum (ER) contact sites called MAMs (Mitochondria-Associated Membranes). HK2 displacement from MAMs with a selective peptide triggers mitochondrial Ca2+ overload caused by Ca2+ release from ER via inositol-3-phosphate receptors (IP3Rs) and by Ca2+ entry through plasma membrane. This results in Ca2+-dependent calpain activation, mitochondrial depolarization and cell death. The HK2-targeting peptide causes massive death of chronic lymphocytic leukemia B cells freshly isolated from patients, and an actionable form of the peptide reduces growth of breast and colon cancer cells allografted in mice without noxious effects on healthy tissues. These results identify a signalling pathway primed by HK2 displacement from MAMs that can be activated as anti-neoplastic strategy.