Survival and functional recovery of primary cortical neurons exposed to actinomycin D

Actinomycin D (ActD) is an antineoplastic antibiotic that has been commonly used for the treatment of various tumors, including Wilms' tumor, rhabdomyosarcoma, and gestational trophoblastic neoplasia. Recent studies have proposed actinomycin D (ActD) as a novel therapeutic candidate for glioblastoma. ActD significantly reduces tumor growth in recurrent glioblastoma patient-derived mouse models and increases survival by downregulating SOX2 expression. However, ActD treatment of brain tumors can lead to unnecessary exposure of surrounding neurons and normal glial cells to ActD. Cellular and molecular studies are required to estimate and minimize the neurological side effects of ActD. This study investigated the short- and long-term toxicological responses of the primary cortical neurons to ActD. We examined concentration-dependent survival of primary cortical neurons and differential susceptibilities of excitatory, inhibitory neurons, and glial cells to ActD. Distinct alterations in intracellular signaling pathways in cortical neurons were also studied when exposed to ActD. Importantly, we found that primary cortical neurons after ActD discontinuation showed active intracellular signaling pathways responding to extracellular neurotropic factors, but they had extremely poor transcription activity reversibility that was inhibited even by 30-min low-dose ActD exposure. These findings indicate the direct toxicity and extremely poor reversibility of ActD in neurons during chemotherapy for brain tumors.