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Open Access Research

PAR2-mediated upregulation of BDNF contributes to central sensitization in bone cancer pain

Yanju Bao1, Wei Hou1, Rui Liu1, Yebo Gao1, Xiangying Kong2, Liping Yang3, Zhan Shi1, Weidong Li1, Honggang Zheng1, Shulong Jiang4, Conghuang Li1, Yinggang Qin1 and Baojin Hua1*

Author Affiliations

1 Department of Oncology, Guang’anmen Hospital, China Academy of Chinese Medical Sciences, Beixiange 5, Xicheng District, 100053 Beijing, China

2 Institute of Chinese Materia Medica, China Academy of Chinese Medical Sciences, Nanxiaojie, Dongzhimen District, 100700 Beijing, China

3 Department of Nephrology, Guang’anmen Hospital, China Academy of Chinese Medical Sciences, Beixiange 5, Xicheng District, 100053 Beijing, China

4 Department of Oncology, Jining First People’s Hospital, Healthy Road 6, 272000 Shandong, China

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Molecular Pain 2014, 10:28  doi:10.1186/1744-8069-10-28

Published: 5 May 2014

Abstract

Background

Bone cancer pain is currently a major clinical challenge for the management of cancer patients, and the cellular and molecular mechanisms underlying the spinal sensitization remain unclear. While several studies demonstrated the critical role of proteinase-activated receptor (PAR2) in the pathogenesis of several types of inflammatory or neuropathic pain, the involvement of spinal PAR2 and the pertinent signaling in the central sensitization is not determined yet in the rodent model of bone cancer pain.

Findings

Implantation of tumor cells into the tibias induced significant thermal hyperalgesia and mechanical allodynia, and enhanced glutamatergic strength in the ipsilateral dorsal horn. Significantly increased brain-derived neurotrophic factor (BDNF) expression was detected in the dorsal horn, and blockade of spinal BDNF signaling attenuated the enhancement of glutamatergic strength, thermal hyperalgesia and mechanical allodynia in the rats with bone cancer pain. Significantly increased spinal PAR2 expression was also observed, and inhibition of PAR2 signaling ameliorated BDNF upsurge, enhanced glutamatergic strength, and thermal hyperalgesia and mechanical allodynia. Inhibition of NF-κB pathway, the downstream of PAR2 signaling, also significantly decreased the spinal BDNF expression, glutamatergic strength of dorsal horn neurons, and thermal hyperalgesia and mechanical allodynia.

Conclusion

The present study demonstrated that activation of PAR2 triggered NF-κB signaling and significantly upregulated the BDNF function, which critically contributed to the enhancement of glutamatergic transmission in spinal dorsal horn and thermal and mechanical hypersensitivity in the rats with bone cancer. This indicated that PAR2 - NF-κB signaling might become a novel target for the treatment of pain in patients with bone cancer.

Keywords:
Proteinase-activated receptor 2; Brain-derived neurotrophic factor; Nuclear factor-κB; Glutamatergic transmission; Bone cancer pain