RNA-binding motif protein 35A is a novel tumor suppressor for colorectal cancer.
RNA-binding motif protein 35A is a novel tumor suppressor for colorectal cancer.
复制标题
DOI：
10.4161/cc.8.3.7679
复制
发表时间：
2009-02-01
期刊：
影响因子：
--
通讯作者：
Ionov Y
中科院分区：
文献类型：
--
作者：
Leontieva OV;Ionov Y
肿瘤中失活基因突变的频繁发生表明突变基因的肿瘤抑制功能。RNA结合基序蛋白35 A（RBM 35 A）在约50%的分析的具有微卫星不稳定性的原发性结肠肿瘤中发生突变。Tet-off调控RBM 35 A基因在缺失RBM 35 A的LS 180结肠癌细胞中的异位表达抑制了体外非贴壁依赖性生长，抑制了体内致瘤潜力，并增强了这些癌细胞的增殖。使用微阵列杂交，我们发现，在响应RBM 35 A表达的一小部分基因显示减少多核糖体相关的mRNA。利用无细胞体外翻译系统的实验表明，RBM 35 A对不同5′非翻译区（UTR）介导的荧光素酶报告基因的翻译有不同的影响。结果表明，RBM 35 A对mRNA的5′ UTR形成的二级结构的吉布斯能（Gibbs energy，ΔG）可以解释RBM 35 A对报告基因翻译效率的不同影响。RBM 35 A对FOS 5′UTR的靶向突变增加了发夹茎形成的ΔG值，从而对该UTR介导的报告基因翻译效率产生了更强的抑制作用。免疫印迹显示，RBM 35 A在LS 180细胞中的异位表达引起了几个癌症相关基因的蛋白质水平的改变。我们的研究结果首次证明RBM 35 A在结肠癌细胞中作为肿瘤抑制因子发挥作用。我们认为RBM 35 A通过mRNA的5′ UTR对蛋白质翻译产生差异效应，参与了许多基因的转录后调控。
The frequent occurrence of inactivating gene mutations in tumors suggests a tumor suppressor function of the mutated gene. The RNA binding motif protein 35A (RBM35A) is mutated in ~50% of analyzed primary colon tumors with microsatellite instability. The Tet-off regulated ectopic expression of RBM35A gene in RBM35A-null LS180 colon carcinoma cells inhibited anchorage-independent growth in vitro, suppressed tumorigenic potential in vivo and enhanced adhesiveness of these cancer cells. Using microarray hybridization we found that in response to RBM35A expression a small fraction of genes showed a decrease in polysome-associated mRNA. Experiments using cell-free in vitro translation system demonstrated that RBM35A differentially affects translation of luciferase reporter mediated by various 5′untranslated regions (UTR). We found that Gibbs energy value (ΔG) of secondary structure formed by 5′UTRs of mRNAs can account for differential effect of RBM35A on reporter translation efficiency. Targeted mutation in the FOS 5′UTR sequence, which increased the ΔG value of hairpin stem formation, resulted in a stronger inhibitory effect of RBM35A on reporter translation efficiency mediated by this UTR. Immunoblotting revealed that ectopic expression of RBM35A in LS180 cells caused alterations in protein levels for several cancer related genes. Our results demonstrate for the first time that RBM35A functions as a tumor suppressor in colon cancer cells. We propose that RBM35A is involved in posttranscriptional regulation of a number of genes by exerting a differential effect on protein translation via 5′UTRs of mRNAs.