Hiasa Masahiro, Okui Tatsuo, Allette Yohance M, Ripsch Matthew S, Sun-Wada Ge-Hong, Wakabayashi Hiroki, Roodman G David, White Fletcher A, Yoneda Toshiyuki
Division of Hematology and Oncology, Indiana University School of Medicine, Indianapolis, Indiana.
Department of Anesthesia, Paul and Carole Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, Indiana.
Cancer Res. 2017 Mar 15;77(6):1283-1295. doi: 10.1158/0008-5472.CAN-15-3545. Epub 2017 Mar 2.
Multiple myeloma patients experience severe bone pain (MMBP) that is undertreated and poorly understood. In this study, we studied MMBP in an intratibial mouse xenograft model that employs JJN3 human multiple myeloma cells. In this model, mice develop MMBP associated in bone with increased sprouting of calcitonin gene-related peptide-positive (CGRP) sensory nerves and in dorsal root ganglia (DRG) with upregulation of phosphorylated ERK1/2 (pERK1/2) and pCREB, two molecular indicators of neuron excitation. We found that JJN3 cells expressed a vacuolar proton pump (V-ATPase) that induced an acidic bone microenvironment. Inhibition of JJN3-colonized bone acidification by a single injection of the selective V-ATPase inhibitor, bafilomycin A1, decreased MMBP, CGRP sensory neuron sprouting, and pERK1/2 and pCREB expression in DRG. CGRP sensory nerves also expressed increased levels of the acid-sensing nociceptor ASIC3. Notably, a single injection of the selective ASIC3 antagonist APETx2 dramatically reduced MMBP in the model. Mechanistic investigations in primary DRG neurons cocultured with JJN3 cells showed increased neurite outgrowth and excitation inhibited by bafilomycin A1 or APETx2. Furthermore, combining APETx2 with bafilomycin A1 reduced MMBP to a greater extent than either agent alone. Finally, combining bafilomycin A1 with the osteoclast inhibitor zoledronic acid was sufficient to ameliorate MMBP, which was refractory to zoledronic acid. Overall, our results show that osteoclasts and multiple myeloma cooperate to induce an acidic bone microenvironment that evokes MMBP as a result of the excitation of ASIC3-activated sensory neurons. Furthermore, they present a mechanistic rationale for targeting ASIC3 on neurons along with the multiple myeloma-induced acidic bone microenvironment as a strategy to relieve MMBP in patients. .
多发性骨髓瘤患者会经历严重的骨痛（MMBP），这种疼痛治疗不足且了解甚少。在本研究中，我们在一个采用JJN3人多发性骨髓瘤细胞的胫骨内小鼠异种移植模型中研究了MMBP。在这个模型中，小鼠出现与骨相关的MMBP，伴有降钙素基因相关肽阳性（CGRP）感觉神经芽生增加，在背根神经节（DRG）中伴有磷酸化ERK1/2（pERK1/2）和pCREB上调，这是神经元兴奋的两个分子指标。我们发现JJN3细胞表达一种液泡质子泵（V - ATPase），可诱导酸性骨微环境。单次注射选择性V - ATPase抑制剂巴弗洛霉素A1抑制JJN3定植骨的酸化，可减轻MMBP、CGRP感觉神经元芽生以及DRG中pERK1/2和pCREB的表达。CGRP感觉神经中酸敏感伤害感受器ASIC3的表达水平也增加。值得注意的是，单次注射选择性ASIC3拮抗剂APETx2可显著减轻模型中的MMBP。与JJN3细胞共培养的原代DRG神经元的机制研究表明，巴弗洛霉素A1或APETx2可抑制神经突生长和兴奋增加。此外，将APETx2与巴弗洛霉素A1联合使用比单独使用任何一种药物能更大程度地减轻MMBP。最后，将巴弗洛霉素A1与破骨细胞抑制剂唑来膦酸联合使用足以改善对唑来膦酸难治的MMBP。总体而言，我们的结果表明破骨细胞和多发性骨髓瘤协同作用诱导酸性骨微环境，由于ASIC3激活的感觉神经元兴奋而引发MMBP。此外，它们为将神经元上的ASIC3与多发性骨髓瘤诱导的酸性骨微环境作为缓解患者MMBP的策略提供了机制依据。
