Ganoderic acid A/DM-induced NDRG2 over-expression suppresses high-grade meningioma growth
Ganoderic acid A/DM-induced NDRG2 over-expression suppresses high-grade meningioma growth
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DOI：
10.1007/s12094-019-02240-6
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发表时间：
2020-07-01
影响因子：
3.4
通讯作者：
Cachia, D.
中科院分区：
文献类型：
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作者：
Das, A.;Alshareef, M.;Cachia, D.
目的N-myc下游调节基因2(NDRG2)在III级脑膜瘤[间变性脑膜瘤]中表达下调，与临床侵袭性行为有关。目前治疗高级别脑膜瘤的方法缺乏，效果有限。本研究的目的是在相关的临床前模型中，验证从食用菌灵芝中提取的结构相关的生物活性三萜化合物(灵芝酸A：GA-A/灵芝酸DM：GA-DM)对人AM进行NDRG2靶向治疗的效果。方法采用3例人AM肿瘤组织标本和对照非肿瘤组织标本，分析NDRG2的表达模式。采用体外细胞培养和体内细胞来源的同种异种AM动物模型，评价GA-A/DM的治疗效果。结果与正常脑组织相比，手术切除的高级别脑膜瘤中NDRG2表达下调。这些结果促使我们使用NDRG2靶向药物GA-A/DM。体外实验结果显示，与最常用的去甲基化药物阿扎替丁和地西他滨相比，25MU GA-A/DM作用72小时可诱导AM细胞死亡，上调NDRG2蛋白表达，下调NDRG2启动子甲基化。我们的结果还表明，GA-A/DM对正常人神经元和蛛网膜细胞没有任何有害影响。GA-A/DM促进细胞凋亡因子(Bax)，抑制基质金属蛋白酶-9、p-P13K、p-AKT、p-mTOR和Wnt-2蛋白表达。在体外模型中，RNAi介导的NDRG2蛋白表达下调促进了肿瘤的增殖，而强制表达wt-NDRG2则抑制了肿瘤的增殖。磁共振(MR)和苏木精(H&E)染色显示，与生理盐水处理的原位AM移植对照相比，GA-A/DM处理的小鼠在5周时肿瘤体积明显缩小。在GA-A/DM处理的动物中，肿瘤细胞的增殖总体上减少，而生存时间增加。酶分析显示GA-A/DM对肝功能无不良影响。结论GA-A/DM可能通过调节NDRG2和改变细胞内信号通路抑制AM的生长，有望成为治疗AM的天然药物。我们已经证明，它可能是一种潜在的治疗AM的有效方法，它可以减少体外细胞增殖，减少肿瘤体积，提高体内存活率。
Purpose N-myc downstream-regulated gene 2 (NDRG2) is down-regulated in grade-III meningioma [anaplastic meningioma (AM)] and associated with clinically aggressive behavior. Current therapies in the treatment of high-grade meningioma are lacking with limited success. This study aims to validate the effect of NDRG2-targeted therapy using structurally related bioactive triterpene compounds derived from the edible mushroom Ganoderma lucidum (ganoderic acid A:GA-A/ganoderic acid DM:GA-DM) in human AM in relevant pre-clinical models. Methods Tissue samples from the AM tumor regions of three human patients and control non-tumor samples were used to analyze the expression pattern of NDRG2. In vitro cell culture and in vivo cell-line-derived orthotopic xenograft animal models of AM were utilized to assess efficacy of treatment with GA-A/DM. Results Downregulation of NDRG2 expression was observed in surgically resected high-grade meningiomas compared to normal brain. These results prompt us to use NDRG2-targeting agents GA-A/DM. In vitro results showed that 72-h treatments of 25 mu M GA-A/DM induced AM cell death, upregulate NDRG2 protein expression, downregulate NDRG2 promoter methylation in meningioma cells as compared to azacitidine and decitabine, the most commonly used demethylating agents. Our results also demonstrated that GA-A/DM does not have any detrimental effect on normal human neurons and arachnoid cells. GA-A/DM promoted apoptotic factors (Bax) while suppressing MMP-9, p-P13K, p-AKT, p-mTOR, and Wnt-2 protein expression. RNAi-mediated knockdown of NDRG2 protein expression increased tumor proliferation, while forced expression of wt-NDRG2 decreased proliferation in an in vitro model. Magnetic resonance (MR) imaging and Hematoxylin (H&E) staining demonstrated gross reduction of tumor volume in GA-A/DM treated mice at 5 weeks when compared with saline-treated orthotopic AM xenografted controls. There was an overall decrease in tumor cell proliferation with increased survival in GA-A/DM-treated animals. Enzyme assays showed that GA-A/DM did not negatively impact hepatic function. Conclusion GA-A/DM may be a promising natural therapeutic reagent in the treatment of AM by suppressing growth via NDRG2 modulation and altering of intracellular signal pathways. We have shown it could potentially be an effective treatment for AM with decreased cellular proliferation in vitro, decreased tumor volume and increased survival in vivo.