MiR-298 suppresses astrocytic NF-κB activity and neuroinflammation via targeting MyD88 in bone cancer pain.

BACKGROUND: Bone cancer pain (BCP), a major symptom impairing quality of life and mobility in cancer patients, is linked to microRNAs dysregulation. This study investigates the role of miR-298 in a mouse BCP model established by implanting tumor cells into the femoral marrow cavity. METHODS: Forty-eight male C3H/HeJ mice were randomized into sham or tumor groups, receiving intrathecal miR- 298 agonist/antagonist or controls. Behavioral assessments (paw withdrawal mechanical threshold [PWMT] and number of spontaneous flinches [NSF]) were performed before and after surgery (days 0, 4, 7, 10, 14, 21, 28). Astrocyte activation, inflammatory cytokines, and pathway proteins (MyD88, TAK1, p-p65) were analyzed via quantitative Reverse Transcription Polymerase Chain Reaction (qRT-PCR), Western blot, and immunofluorescence. Statistical analysis used one-way ANOVA with Tukey's test and independent t-tests (P < 0.05). RESULTS: Tumor-implanted mice showed significant mechanical hypersensitivity in PWMT and NSF versus sham controls (P < 0.001). MiR-298 expression was markedly downregulated in BCP mice (P < 0.001), confirmed by fluorescence in situ hybridization and qRT-PCR. Overexpression of miR-298 suppressed astrocyte proliferation (P = 0.005) and pro-inflammatory cytokines (tumor necrosis factor-α, interleukin-1β; P < 0.001), while enhancing apoptosis (P = 0.003). Luciferase assays confirmed MyD88 as a direct miR-298 target (P < 0.001). Intrathecal miR-298 agonist reduced NF-κB activation (phospho-p65, P < 0.001) and alleviated pain behaviors versus tumor controls (P < 0.001). CONCLUSIONS: MiR-298 reduces BCP in mice by inhibiting astrocyte-mediated neuroinflammation and blocking the MyD88/NF-κB pathway.