我们前期研究发现，P2X3R在DRG神经元的功能性上调,可以引起神经元的超兴奋性和骨癌痛。但是在癌症痛的发展过程中，通过何种机制来调控P2X3R转录合成和表达，仍然是一个有待解决的关键科学问题。我们预实验表明：转录因子Runx1可能会通过对P2X3R的转录调控而参与癌症痛。研究报道,细胞因子能够通过ERK磷酸化Runx1来增强其转录活性。我们预实验提示,GDNF可能会激活ERK而磷酸化Runx1,进而促进P2X3R转录合成。本项目拟通过以下研究阐明P2X3R的转录调控机制及其在骨癌痛中的作用：1)阐明Runx1促进P2X3R转录的分子机制及其在癌症痛中的作用；2)确定ERK激活在Runx1磷酸化及P2X3R转录中的作用；3)确定GDNF对ERK的激活,阐明GDNF/ERK/Runx1通路在P2X3R转录调控及癌症痛中的作用。该研究将有助于阐明癌症痛的发病机理,为骨癌痛的药物治疗提供新靶点。

Our previous study has documented that functional upregulation of P2X3 receptors (P2X3R) in dorsal root ganglion (DRG) contributes to the hyperexcitability of nociceptive sensory neurons and then to the bone cancer-induced pain. However, the transcriptional mechanisms underlying the sustaining synthesis and expression of these receptors during the development of bone cancer pain still remain largely unknown. In our pilot study, we have found that transcription factor Runx1 modulates the expression of P2X3R in DRG neurons and thereby participating in the pathogenesis of bone cancer pain. Accumulative evidence has shown that Runx1 functions are potentially regulated by extracellular signal-regulated kinase (ERK), which is activated by multiple cytokines. It is reported that ERK-dependent phosphorylation potentiates the transcriptional activity of Runx1. Our preliminary experiments also showed that GDNF (glial cell-derived neurotrophic factor) could result in the increases of both P2X3R mRNA and protein through the activation of ERK-dependent Runx1 phosphorylation..In this research project, we will perform the following studies to investigate the mechanisms underlying the transcriptional regulation of P2X3R in cancer rat DRG neurons, as well as its role in bone cancer pain: (1) examining the transcriptional regulation of p2x3r gene by Runx1 and its contribution to the development of bone cancer pain, and then clarifying the molecular mechanisms by which how Runx1 promotes P2X3R transcription; (2) investigating the role for ERK pathway activation in phosphorylation of Runx1, and validating the necessary of ERK-dependent Runx1 phosphorylation for the transcriptional regulation of P2X3R; (3) exploring the contribution of GDNF to the activation of ERK pathway that subsequently phosphorylates Runx1 at serine 249 (Ser249) site, thereby elucidating the role for GDNF/GFRα1/Ret/ERK pathway-mediated Runx1 Ser249 phosphorylation in transcriptional regulation of P2X3R and its contribution to the development of bone cancer pain. This study will be helpful to elucidate the pathogenic mechanisms of bone cancer pain, and therefore provide a novel target for the treatment of bone cancer pain.