Liu Jing, Wang Yaming, Sun Xuefei, Ji Nan, Sun Shengjun, Wang Yajie, Liu Fusheng, Cui Qu, Wang Chen, Liu Yuanbo
Department of Hematology, Beijing Tiantan Hospital, Capital Medical University, Beijing 100050, P.R. China.
Department of Neurosurgery, Navy General Hospital, Beijing 100050, P.R. China.
Oncol Rep. 2017 Feb;37(2):887-894. doi: 10.3892/or.2016.5308. Epub 2016 Dec 8.
The Src homology region 2 domain-containing phosphatase-1 (SHP1) is a critical negative regulator involved in the JAK/STAT signaling pathway. The SHP1 gene has been proposed as a candidate tumor suppressor in solid and hematological malignancies and promoter methylation is an important biological process in controlling tumorigenesis. However, the detailed roles of SHP1 promoter methylation in the pathogenesis of primary central nervous system lymphoma (PCNSL) is largely unknown. In the present study, we evaluated the correlation between SHP1 expression and promoter methylation in patients with PCNSL. Thirty-three patients with PCNSL were included. We evaluated SHP1 protein expression levels by immunohistochemistry and the SHP1 promoter methylation profile by pyrosequencing analysis. For cases (n=8) with a good yield of total protein, SHP1 phosphorylation (pSHP1) and STAT3 protein expression levels were further analyzed by western blot analysis to uncover the molecular impact of SHP1 promoter methylation on downstream signaling pathways. In this study, a lower expression of SHP1 protein level was observed in 16/33 cases (48.5%) of PCNSL. SHP1 promoter methylation was predominant in 29/33 cases (87.9%) with a mean methylation level of 31.7±36.5%. The mean methylation level of the SHP1 promoter was significantly elevated in patients with a lower SHP1 protein expression, compared with those showing a higher SHP1 protein expression (50.3±38.9 vs. 14.2±24.0%, p=0.004). Further analysis showed that SHP1 protein expression was significantly decreased in patients with a higher SHP1 promoter methylation status (p=0.001), and such attenuation was correlated with a downregulation of pSHP1 (p=0.005) and an upregulation of STAT3 protein expression (p=0.020). Our data demonstrated that epigenetic alterations in the promoter region downregulated SHP1 expression in PCNSL patients. SHP1 promoter methylation was correlated with tyrosine phosphorylation and activation of transcription factor STAT3, which may contribute to the pathogenesis of PCNSL. Therapeutical regimens with epigenetic modifiers may be a potential option for patients with PCNSL.
含Src同源区2结构域的磷酸酶-1（SHP1）是参与JAK/STAT信号通路的关键负调节因子。SHP1基因已被提出作为实体瘤和血液系统恶性肿瘤的候选肿瘤抑制基因，启动子甲基化是控制肿瘤发生的重要生物学过程。然而，SHP1启动子甲基化在原发性中枢神经系统淋巴瘤（PCNSL）发病机制中的具体作用尚不清楚。在本研究中，我们评估了PCNSL患者中SHP1表达与启动子甲基化之间的相关性。纳入了33例PCNSL患者。我们通过免疫组织化学评估SHP1蛋白表达水平，并通过焦磷酸测序分析评估SHP1启动子甲基化谱。对于总蛋白产量良好的病例（n = 8），通过蛋白质印迹分析进一步分析SHP1磷酸化（pSHP1）和STAT3蛋白表达水平，以揭示SHP1启动子甲基化对下游信号通路的分子影响。在本研究中，在33例PCNSL病例中的16例（48.5%）中观察到SHP1蛋白水平表达较低。SHP1启动子甲基化在33例病例中的29例（87.9%）中占主导地位，平均甲基化水平为31.7±36.5%。与SHP1蛋白表达较高的患者相比，SHP1蛋白表达较低的患者中SHP1启动子的平均甲基化水平显著升高（50.3±38.9 vs. 14.2±24.0%，p = 0.004）。进一步分析表明，SHP1启动子甲基化状态较高的患者中SHP1蛋白表达显著降低（p = 0.001），这种减弱与pSHP1的下调（p = 0.005）和STAT3蛋白表达的上调（p = 0.020）相关。我们的数据表明，启动子区域的表观遗传改变下调了PCNSL患者中的SHP1表达。SHP1启动子甲基化与转录因子STAT3的酪氨酸磷酸化和激活相关，这可能有助于PCNSL的发病机制。使用表观遗传修饰剂的治疗方案可能是PCNSL患者的一种潜在选择。
