mTOR inhibition and levels of the DNA repair protein MGMT in T98G glioblastoma cells.
mTOR inhibition and levels of the DNA repair protein MGMT in T98G glioblastoma cells.
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DOI：
10.1186/1476-4598-13-144
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发表时间：
2014-06-08
期刊：
影响因子：
37.3
通讯作者：
Morley SJ
中科院分区：
文献类型：
--
作者：
Smalley S;Chalmers AJ;Morley SJ
多形性胶质母细胞瘤（GBM）是最常见和最具侵袭性的原发性成人脑肿瘤，对常规治疗反应不佳。替莫唑胺（TMZ）化疗仍然是最常用的治疗，尽管很大比例的肿瘤显示TMZ耐药。60%的GBM肿瘤具有未甲基化的MGMT启动子区域，导致DNA修复蛋白O 6-甲基鸟嘌呤-DNA甲基转移酶（MGMT）的过度表达，这是肿瘤对TMZ化疗耐药的原因。肿瘤还经常表现出过度活跃的PI 3-激酶/mTOR信号传导，这使它们能够快速再合成蛋白质。由于MGMT是一种自杀蛋白，在结合和修复TMZ诱导的O 6-甲基鸟嘌呤加合物时降解，因此假设通过mTOR信号传导途径抑制翻译可产生MGMT蛋白的肿瘤特异性降低并增加TMZ敏感性。在转录后、翻译和蛋白水平监测MGMT，以确定mTOR抑制对体外MGMT蛋白表达的影响。我们发现，抑制mTOR信号传导确实与蛋白质合成的急性抑制有关。Western印迹显示，尽管如此，相对于加载对照蛋白，MGMT蛋白的稳态水平增加，并且MGMT mRNA保留在重质多聚核糖体中。虽然TMZ处理导致维持MGMT蛋白水平，但用TMZ和KU 0063794同时处理T98 G细胞导致MGMT蛋白水平增加，而总mRNA水平没有变化。这些体外数据表明，与直觉相反，mTOR抑制可能不是TMZ治疗的有用辅助手段，在临床环境中应用mTOR抑制剂之前需要进行更多研究。
Glioblastoma multiforme (GBM), the most common and most aggressive type of primary adult brain tumour, responds poorly to conventional treatment. Temozolomide (TMZ) chemotherapy remains the most commonly used treatment, despite a large proportion of tumours displaying TMZ resistance. 60% of GBM tumours have unmethylated MGMT promoter regions, resulting in an overexpression of the DNA repair protein O6-methylguanine-DNA methyltransferase (MGMT), which is responsible for tumour resistance to TMZ chemotherapy. Tumours also often exhibit hyperactive PI3-kinase/mTOR signalling, which enables them to resynthesise proteins quickly. Since MGMT is a suicide protein that is degraded upon binding to and repairing TMZ-induced O6-methylguanine adducts, it has been hypothesized that inhibition of translation via the mTOR signalling pathway could generate a tumour-specific reduction in MGMT protein and increase TMZ sensitivity. MGMT was monitored at the post-transcriptional, translational and protein levels, to determine what effect mTOR inhibition was having on MGMT protein expression in vitro. We show that inhibiting mTOR signalling is indeed associated with acute inhibition of protein synthesis. Western blots show that despite this, relative to loading control proteins, steady state levels of MGMT protein increased and MGMT mRNA was retained in heavy polysomes. Whilst TMZ treatment resulted in maintained MGMT protein levels, concomitant treatment of T98G cells with TMZ and KU0063794 resulted in increased MGMT protein levels without changes in total mRNA levels. These in vitro data suggest that, counterintuitively, mTOR inhibition may not be a useful adjunct to TMZ therapy and that more investigation is needed before applying mTOR inhibitors in a clinical setting.
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影响因子：
158.5
作者：
Stupp, R;Mason, WP;Ryan, G
通讯作者：
Ryan, G
DOI：
10.1016/0027-5107(90)90156-x
发表时间：
1990-11-01
期刊：
MUTATION RESEARCH
影响因子：
--
作者：
LUDLUM, DB
通讯作者：
LUDLUM, DB
DOI：
10.1126/science.1164382
发表时间：
2008-09-26
期刊：
Science (New York, N.Y.)
影响因子：
--
作者：
Parsons DW;Jones S;Zhang X;Lin JC;Leary RJ;Angenendt P;Mankoo P;Carter H;Siu IM;Gallia GL;Olivi A;McLendon R;Rasheed BA;Keir S;Nikolskaya T;Nikolsky Y;Busam DA;Tekleab H;Diaz LA Jr;Hartigan J;Smith DR;Strausberg RL;Marie SK;Shinjo SM;Yan H;Riggins GJ;Bigner DD;Karchin R;Papadopoulos N;Parmigiani G;Vogelstein B;Velculescu VE;Kinzler KW
通讯作者：
Kinzler KW
影响因子：
64.8
作者：
Uniacke J;Holterman CE;Lachance G;Franovic A;Jacob MD;Fabian MR;Payette J;Holcik M;Pause A;Lee S
通讯作者：
Lee S
影响因子：
3.7
作者：
Shah N;Lin B;Sibenaller Z;Ryken T;Lee H;Yoon JG;Rostad S;Foltz G
通讯作者：
Foltz G