Cannabinoid receptor subtype 2 (CB2R): Features and targets for medical applications

CB2R belongs to the Endocannabinoid System (ECS). CB2R is gaining great attention as its activation may lead to pivotal effect involved in neurodegeneration and cancer disease, and it is devoid of the side effects due to the brain CB1R stimulation. In the central nervous system (CNS), CB2R activation can induce the microglia polarization from the proinflammatory M1 state to the anti-inflammatory M2 state, exerting neuroinflammation mitigation. Therefore, CB2R agonists are considered neuroprotective agents. In several cancers, CB2R activation leads to the inhibition of proliferation, autophagy, and apoptosis, through different pathways; thus, CB2R agonists are considered promising anticancer drugs. Several studies are ongoing on the potential use of CB2R inverse agonists/antagonists and allosteric modulators. CB2R fluorescent ligands have been developed as tools to study CB2R localization and dynamics in whole live cells in order to deepen the CB2R-mediated pathways.