Anwulignan Alleviates Bone Cancer Pain by Modulating the PPARα/CXCR2 Signaling Pathway in the Rat Spinal Cord

AIMS: Advanced cancer patients frequently endure severe pain from bone metastases, and few effective treatments for bone cancer pain (BCP) exist. Although Anwulignan is known for its antioxidant, anti-inflammatory, and antitumor properties, its effects on BCP remain unclear. This study aims to explore the analgesic effects and mechanisms of Anwulignan on bone cancer pain. METHODS: Western blotting and immunofluorescence assessed molecular expression and localization. X-ray, micro-CT, TRAP, and ALP staining examined bone destruction in rats. MTT, colony formation assays, and in vivo imaging analyzed tumor changes. RNA-Seq identified differentially expressed genes, validated by ChIP analysis. RESULTS: Here, we showed that Anwulignan alleviated mechanical, thermal, and cold hypersensitivity and spontaneous pain, prevented bone destruction, and suppressed local tumor growth in rats with BCP. Furthermore, Anwulignan was firmly bound to proliferator-activated receptor alpha (PPARα), increasing its thermal stability. Intrathecal (i.t.) injection of PPARα siRNA increased pain sensitivity in naive rats, and PPARα siRNA abrogated the analgesic effect of Anwulignan in BCP model rats. Moreover, the PPARα agonist pirinixic acid reduced BCP hypersensitivity and abrogated the upregulation of CXC chemokine receptor 2 (CXCR2). Importantly, PPARα bound to the CXCR2 promoter region, and Anwulignan could reverse the reduced binding of PPARα to CXCR2 caused by BCP. CONCLUSION: Taken together, these results indicate that Anwulignan is a potential antitumor and analgesic agent that exerts its effects via upregulation of PPARα expression to inhibit the expression of CXCR2 and could be used for treating BCP.