Metabotropic glutamate receptors: new targets for the control of tumor growth?

Cancer stem cells are currently a target for the treatment of malignant tumors. Transformed neural stem–progenitor cells of the brain subventricular zone and the external granular layer of the cerebellum are the putative cells of origin of malignant gliomas and medulloblastomas, which are the most frequent malignant brain tumors in adults and children, respectively. The proliferation of neural stem–progenitor cells is regulated by metabotropic glutamate (mGlu) receptors, which are G-protein-coupled receptors that are activated by glutamate, the major excitatory neurotransmitter of the CNS. At least two receptor subtypes – mGlu3 and mGlu4 receptors – control the proliferation of brain tumor cells, whereas mGlu1 receptors have been implicated in the development of melanomas. We believe that individual mGlu receptor subtypes represent new potential targets for the treatment of several malignant tumors, including brain tumors.