JAG-1/Notch signaling axis contributes to the maintenance of bone cancer pain in female rats via spinal astrocyte-neuron crosstalk

Abstract

Abstract Background Recent studies have shown that interactions between astrocytes and neurons in the spinal cord are involved in chronic pain. In this study, we investigated whether the Jagged-1(JAG-1) /Notch signaling pathway regulates bone cancer pain (BCP) via the astrocyte-neuron mechanism. Methods Walker256 breast cancer cells were injected into the tibia bone marrow of the female rat to establish a stable BCP rat model. The molecular mechanism of hyperalgesia mediated by the JAG-1/Notch signal pathway was determined by western blotting, immunofluorescence, real-time quantitative polymerase chain reaction, dual-luciferase reporter gene, and chromatin immunoprecipitation assays. Von-Frey test, catwalk gait analysis, open field test, and conditioned place aversion test were used to study changes in pain behavior in rats. In addition, the effect of the JAG-1/Notch signal pathway on neuronal excitability was also investigated. Results The intramedullary injection of Walker256 breast cancer cells induces persistent hyperalgesia and increased the expression of JAG-1, Notch intracellular domain (NICD), and c-Fos in the spinal cord. The expression of JAG-1 was exclusively observed in astrocytes and Notch-1 was expressed only in neuronal cells. Astrocyte activation increased JAG-1 expression, and knockdown of JAG-1 in the spinal cord reduced BCP. The supplementation of exogenous JAG-1 to the spinal cord induced BCP-like behavior and promoted expression of c-Fos and hairy and enhancer of split homolog-1 (Hes-1) in the spinal cord of the naïve rats. These effects were reversed when the rats were administered intrathecal injections of DAPT, an inhibitor of notch signaling. The intrathecal injection of DAPT reduced BCP and inhibited Hes-1 and c-Fos expression in the spinal cord. Furthermore, our results showed that JAG-1 regulated neural excitability via the Notch signaling pathway. JAG-1 upregulated Hes-1 expression by inducing the recruitment of NICD to the RBP-J/CSL binding site located within the Hes-1 promoter sequence. Finally, the intrathecal injection of c-Fos-ASO and administration of sh-Hes-1 to the spinal dorsal horn also alleviated BCP. Conclusion JAG-1/Notch signaling axis mediated interaction of astrocyte-neuron contributes to the maintenance of bone cancer-induced pain hypersensitivity. The inhibition of the crosstalk between astrocytic JAG-1 and neuronal Notch-1 may serve as a potential strategy for the treatment of BCP.