Ermoian Ralph P, Kaprealian Tania, Lamborn Kathleen R, Yang Xiaodong, Jelluma Nannette, Arvold Nils D, Zeidman Ruth, Berger Mitchel S, Stokoe David, Haas-Kogan Daphne A
Department of Radiation Oncology, The University of California, San Francisco, 1600 Divisadero St. Suite H1031, San Francisco, CA, 94143-1708, USA.
J Neurooncol. 2009 Jan;91(1):19-26. doi: 10.1007/s11060-008-9683-5. Epub 2008 Sep 1.
To interrogate grade II, III, and IV gliomas and characterize the critical effectors within the PI3-kinase pathway upstream and downstream of mTOR. Experimental design Tissues from 87 patients who were treated at UCSF between 1990 and 2004 were analyzed. Twenty-eight grade II, 17 grade III glioma, 26 grade IV gliomas, and 16 non-tumor brain specimens were analyzed. Protein levels were assessed by immunoblots; RNA levels were determined by polymerase chain reaction amplification. To address the multiple comparisons, first an overall analysis was done comparing the four groups using Spearman's Correlation Coefficient. Only if this analysis was statistically significant were individual pairwise comparisons done.
Multiple comparison analyses revealed a significant correlation with grade for all variables examined, except phosphorylated-S6. Expression of phosphorylated-4E-BP1, phosphorylated-PKB/Akt, PTEN, TSC1, and TSC2 correlated with grade (P < 0.01 for all). We extended our analyses to ask whether decreases in TSC proteins levels were due to changes in mRNA levels, or due to changes in post-transcriptional alterations. We found significantly lower levels of TSC1 and TSC2 mRNA in GBMs than in grade II gliomas or non-tumor brain (P < 0.01).
Expression levels of critical signaling molecules upstream and downstream of mTOR differ between non-tumor brain and gliomas of any grade. The single variable whose expression did not differ between non-tumor brain and gliomas was phosphorylated-S6, suggesting that other protein kinases, in addition to mTOR, contribute significantly to S6 phosphorylation. mTOR provides a rational therapeutic target in gliomas of all grades, and clinical benefit may emerge as mTOR inhibitors are combined with additional agents.
研究II级、III级和IV级胶质瘤，并确定mTOR上游和下游PI3激酶通路中的关键效应分子。实验设计：分析了1990年至2004年间在加州大学旧金山分校接受治疗的87例患者的组织。分析了28例II级、17例III级胶质瘤、26例IV级胶质瘤和16例非肿瘤脑标本。通过免疫印迹评估蛋白质水平；通过聚合酶链反应扩增测定RNA水平。为了处理多重比较，首先使用Spearman相关系数对四组进行总体分析。只有当该分析具有统计学意义时，才进行个体两两比较。
多重比较分析显示，除磷酸化S6外，所有检测变量与分级均存在显著相关性。磷酸化4E-BP1、磷酸化PKB/Akt、PTEN、TSC1和TSC2的表达与分级相关（所有P<0.01）。我们进一步分析，以确定TSC蛋白水平的降低是由于mRNA水平的变化，还是由于转录后改变。我们发现，胶质母细胞瘤中TSC1和TSC2 mRNA水平显著低于II级胶质瘤或非肿瘤脑（P<0.01）。
非肿瘤脑与任何分级的胶质瘤之间，mTOR上游和下游关键信号分子的表达水平存在差异。非肿瘤脑与胶质瘤之间表达无差异的单一变量是磷酸化S6，这表明除mTOR外，其他蛋白激酶对S6磷酸化也有显著贡献。mTOR为所有分级的胶质瘤提供了一个合理的治疗靶点，将mTOR抑制剂与其他药物联合使用可能会带来临床益处。
