Suppression of histone deacetylases by SAHA relieves bone cancer pain in rats via inhibiting activation of glial cells in spinal dorsal horn and dorsal root ganglia
Suppression of histone deacetylases by SAHA relieves bone cancer pain in rats via inhibiting activation of glial cells in spinal dorsal horn and dorsal root ganglia
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SAHA 抑制组蛋白脱乙酰酶可通过抑制脊髓背角和背根神经节中神经胶质细胞的活化来缓解大鼠的骨癌疼痛。
DOI：
10.1186/s12974-020-01740-5
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发表时间：
2020-04-22
影响因子：
9.3
通讯作者：
Dong, Yu-Lin
中科院分区：
文献类型：
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作者：
He, Xiao-Tao;Hu, Xiao-Fan;Dong, Yu-Lin
背景 据报道，在骨癌痛（BCP）的发病过程中，神经胶质细胞会出现强烈的激活。我们团队及其他研究人员已表明，组蛋白去乙酰化酶（HDACs）在调节神经胶质细胞介导的免疫反应中发挥着重要作用；然而，在BCP发展过程中，HDACs是否参与神经胶质细胞的激活仍不明确。
方法 通过胫骨内接种肿瘤细胞（TCI）建立BCP模型。分别采用蛋白质免疫印迹法和免疫荧光染色法评估脊髓背角和背根神经节中组蛋白去乙酰化酶（HDACs）的表达水平及分布位点。随后，腹腔注射和鞘内注射临床使用的HDAC抑制剂辛二酰苯胺异羟肟酸（SAHA），以挽救HDAC1和HDAC2表达水平的升高。通过测量缩爪阈值（PWTs）评估SAHA对BCP的镇痛效果。进一步通过免疫荧光染色和蛋白质免疫印迹分析评估SAHA对TCI大鼠脊髓背角和背根神经节中神经胶质细胞激活及促炎细胞因子（肿瘤坏死因子-α、白细胞介素-1β和白细胞介素-6）表达的影响。随后，通过苏木精-伊红（HE）染色和显微CT扫描分析SAHA对肿瘤生长及癌细胞诱导的骨质破坏的影响。
结果 TCI导致脊髓背角和背根神经节神经胶质细胞中HDAC1/HDAC2的表达迅速且持久增加。SAHA抑制HDACs不仅逆转了TCI诱导的HDACs上调，还抑制了脊髓背角和背根神经节中神经胶质细胞的激活，并缓解了TCI诱导的机械性异常疼痛。此外，我们发现给予SAHA无法阻止肿瘤浸润或胫骨的骨质破坏，这表明SAHA的镇痛作用并非源于其抗肿瘤作用。而且，我们发现给予SAHA可抑制脊髓背角和背根神经节中糖原合成酶激酶3β（GSK3β）的活性，这可能有助于缓解BCP。
结论 我们的研究结果表明，HDAC1和HDAC2参与了BCP发病机制中脊髓背角和背根神经节内神经胶质细胞介导的神经炎症，这表明SAHA抑制HDACs可能是缓解BCP疼痛的一种潜在策略。
BackgroundRobust activation of glial cells has been reported to occur particularly during the pathogenesis of bone cancer pain (BCP). Researchers from our group and others have shown that histone deacetylases (HDACs) play a significant role in modulating glia-mediated immune responses; however, it still remains unclear whether HDACs are involved in the activation of glial cells during the development of BCP.MethodsBCP model was established by intra-tibia tumor cell inoculation (TCI). The expression levels and distribution sites of histone deacetylases (HDACs) in the spinal dorsal horn and dorsal root ganglia were evaluated by Western blot and immunofluorescent staining, respectively. Suberoylanilide hydroxamic acid (SAHA), a clinically used HDAC inhibitor, was then intraperitoneally and intrathecally injected to rescue the increased expression levels of HDAC1 and HDAC2. The analgesic effects of SAHA administration on BCP were then evaluated by measuring the paw withdrawal thresholds (PWTs). The effects of SAHA on activation of glial cells and expression of proinflammatory cytokines (TNF-α, IL-1β, and IL-6) in the spinal dorsal horn and dorsal root ganglia of TCI rats were further evaluated by immunofluorescent staining and Western blot analysis. Subsequently, the effects of SAHA administration on tumor growth and cancer cell-induced bone destruction were analyzed by hematoxylin and eosin (HE) staining and micro-CT scanning.ResultsTCI caused rapid and long-lasting increased expression of HDAC1/HDAC2 in glial cells of the spinal dorsal horn and dorsal root ganglia. Inhibiting HDACs by SAHA not only reversed TCI-induced upregulation of HDACs but also inhibited the activation of glial cells in the spinal dorsal horn and dorsal root ganglia, and relieved TCI-induced mechanical allodynia. Further, we found that SAHA administration could not prevent cancer infiltration or bone destruction in the tibia, which indicated that the analgesic effects of SAHA were not due to its anti-tumor effects. Moreover, we found that SAHA administration could inhibit GSK3β activity in the spinal dorsal horn and dorsal root ganglia, which might contributed to the relief of BCP.ConclusionOur findings suggest that HDAC1 and HDAC2 are involved in the glia-mediated neuroinflammation in the spinal dorsal horn and dorsal root ganglia underlying the pathogenesis of BCP, which indicated that inhibiting HDACs by SAHA might be a potential strategy for pain relief of BCP.