Activation of STAT3-mediated CXCL12 up-regulation in the dorsal root ganglion contributes to oxaliplatin-induced chronic pain.

Oxaliplatin-induced chronic painful neuropathy is the most common dose-limiting adverse event that negatively affects cancer patients' quality of life. However, the underlying molecular mechanisms are still unclear. In the present study, we found that the intraperitoneal administration of oxaliplatin at 4 mg/kg for five consecutive days noticeably upregulated the expression of CXC motif ligand 12 (CXCL12) in the dorsal root ganglion, and the intrathecal injection of an anti-CXCL12 neutralizing antibody or CXCL12 siRNA attenuated the mechanical allodynia and thermal hyperalgesia induced by oxaliplatin. We also found that the signal transducers and transcription activator 3 (STAT3) was activated in the dorsal root ganglion, and inhibition of STAT3 with S3I-201 or the injection of AAV-Cre-GFP into STAT3flox/flox mice prevented the upregulation of CXCL12 expression in the dorsal root ganglion and chronic pain following oxaliplatin administration. Double-label fluorescent immunohistochemistry findings also showed that p-STAT3 was mainly localized in CXCL12-positive cells in the dorsal root ganglion. Furthermore, the results of a chromatin immunoprecipitation assay revealed that p-STAT3 might be essential for oxaliplatin-induced CXCL12 upregulation via binding directly to the specific position of the CXCL12 gene promoter. Finally, we found that cytokine TNF-α and IL-1β increases mediated the STAT3 activation following oxaliplatin treatment. Taken together, these findings suggested that the upregulation of CXCL12 via TNF-α/IL-1β-dependent STAT3 activation contributes to oxaliplatin-induced chronic pain.