Regulation of p27Kip1 by miRNA 221/222 in Glioblastoma
Regulation of p27Kip1 by miRNA 221/222 in Glioblastoma
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DOI：
10.4161/cc.6.16.4526
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发表时间：
2007-08-15
期刊：
影响因子：
4.3
通讯作者：
Lorimer, Ian A. J.
中科院分区：
文献类型：
--
作者：
Gillies, Jana K.;Lorimer, Ian A. J.
P27(Kip1)是细胞周期的关键负性调节因子，在癌症中通常会降低。在大多数癌症中，p27(Kip1)的mRNA水平没有变化，p27(Kip1)蛋白的蛋白分解增加被认为是其下调的主要机制。在这里，我们表明p27(Kip1)蛋白水平也受到癌细胞中microRNAs的下调。我们使用RNA干扰来降低人胶质母细胞瘤细胞系中DICER的水平，发现这会导致p27(Kip1)水平的增加和细胞增殖的下降。当p27(Kip1)基因3‘非编码区的编码序列插入荧光素酶报告基因下游时，DICER耗竭也增强了报告基因产物的表达。MicroRNA靶点软件TargetScan预测，p27(Kip1)mRNA的3‘非编码区包含多个microRNAs位点。其中包括microRNA221和222的两个位点，这两个位点已被证明在胶质母细胞瘤中上调，相对于邻近的正常脑组织。MicroRNA221和microRNA222的基因位于X染色体上的相邻位置；它们的表达似乎是协同调节的，而且它们似乎也具有相同的靶标特异性。在胶质母细胞瘤细胞中，microRNA221或222的拮抗作用也导致p27(Kip1)水平的增加和与p27(Kip1)3‘UTR融合的荧光素酶报告基因的表达增强。这些数据表明，p27(Kip1)是microRNAs221和222的直接靶标，并提示这些microRNAs在促进人胶质母细胞瘤侵袭性生长中发挥作用。
Levels of p27(Kip1), a key negative regulator of the cell cycle, are often decreased in cancer. In most cancers, levels of p27(Kip1) mRNA are unchanged and increased proteolysis of the p27(Kip1) protein is thought to be the primary mechanism for its downregulation. Here we show that p27(Kip1) protein levels are also downregulated by microRNAs in cancer cells. We used RNA interference to reduce Dicer levels in human glioblastoma cell lines and found that this caused an increase in p27(Kip1) levels and a decrease in cell proliferation. When the coding sequence for the 3'UTR of the p27(Kip1) mRNA was inserted downstream of a luciferase reporter gene, Dicer depletion also enhanced expression of the reporter gene product. The microRNA target site software TargetScan predicts that the 3'UTR of p27(Kip1) mRNA contains multiple sites for microRNAs. These include two sites for microRNA 221 and 222, which have been shown to be upregulated in glioblastoma relative to adjacent normal brain tissue. The genes for microRNA 221 and microRNA 222 occupy adjacent sites on the X chromosome; their expression appears to be coregulated and they also appear to have the same target specificity. Antagonism of either microRNA 221 or 222 in glioblastoma cells also caused an increase in p27(Kip1) levels and enhanced expression of the luciferase reporter gene fused to the p27(Kip1) 3'UTR. These data show that p27(Kip1) is a direct target for microRNAs 221 and 222, and suggest a role for these microRNAs in promoting the aggressive growth of human glioblastoma.