Methotrexate induces astrocyte apoptosis by disrupting folate metabolism in the mouse juvenile central nervous system

Methotrexate (MTX) is a folic acid antagonist and widely used for acute lymphoblastic leukemia (ALL) in children. MTX is associated with acute and chronic neurotoxicity during treatment, however the underlying mechanism is still poorly understood. In this study we investigate whether MTX is neurovirulent to astrocytes in the Central Nervous System (CNS) of adolescent mice. We demonstrated that MTX induced severe cytotoxicity in C6 astrocyte-like cell line and rat primary cultures of astrocytes in a dose-dependent manner. Moreover, GFAP-labeled astrocyte cells significantly decreased in the mouse spinal cord and brain. Furthermore, protein levels of PARP and pro-Caspase-3 were reduced by MTX, indicating MTX-induced apoptosis leads to the astrocytes loss. Notably, overexpression of dihydrofolate reductase (DHFR) or exogenous addition of folate markedly reversed the astrocytes toxicity induced by MTX through activating folate metabolism pathway. Taken together, our study provides evidence for neurotoxic effect of MTX-induced astrocytes apoptosis both in vitro and in vivo with disruption of folate metabolism, and additional supplement of folate may provide novel approaches for alleviating the astrocytes toxicity induced by MTX in the clinic.