Depletion of three combined THOC5 mRNA export protein target genes synergistically induces human hepatocellular carcinoma cell death
Depletion of three combined THOC5 mRNA export protein target genes synergistically induces human hepatocellular carcinoma cell death
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DOI：
10.1038/onc.2015.433
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发表时间：
2016-07-01
期刊：
影响因子：
8
通讯作者：
Tamura, T.
中科院分区：
文献类型：
--
作者：
Saran, S.;Tran, D. D. H.;Tamura, T.
肝细胞癌（HCC）是一种常见的癌症，预后不良，医疗干预的可能性有限。已经表明，超过100个推定的驱动基因与HCC中的多个反复改变的途径相关，这表明对于任何治疗方法，都需要抑制多个途径。mRNA加工受复杂的RNA-蛋白质网络调节，该网络对于维持体内平衡至关重要。THOC 5是mRNA输出复合物的成员，在不到1%的mRNA加工中发挥作用，并且是细胞生长和分化所需的，但不是正常成纤维细胞、肝细胞和巨噬细胞中细胞存活所需的。在这份报告中，我们表明，在人肝癌细胞系Huh 7和HepG 2中，50%的THOC 5耗竭诱导细胞凋亡。使用去除THOC 5的细胞进行的转录组分析显示，396个基因，如跨膜BAX抑制剂基序包含4（TMBIM 4）、跨膜emp 24样运输蛋白10（Tmed 10）和D-酪氨酰-tRNA脱酰酶2（Dtd 2）基因在两种细胞系中下调。在Huh 7或HepG 2中这些TH 0 C 5靶基因之一的缺失没有显著诱导细胞死亡，表明这些可能是HCC细胞存活的微调因子。然而，这些基因的组合缺失协同增加了TUNEL（末端脱氧核苷酸转移酶dUTP缺口末端标记）阳性肝癌的数量。必须注意的是，这些基因的缺失不会诱导肝细胞系THLE-2细胞中的细胞死亡。原发性肝癌中78%的细胞分化程度为G2和G3的肿瘤中THOC 5表达增强。此外，一个假定的糖蛋白，Tmed 10的表达，与原发性肝癌中的THOC 5表达水平相关，这表明该蛋白可能是一种新的肝癌生物标志物。这些数据表明，抑制多个THOC 5靶基因可能代表了HCC治疗的新策略。
Hepatocellular carcinoma (HCC) is a frequent form of cancer with a poor prognosis and with limited possibilities of medical intervention. It has been shown that over 100 putative driver genes are associated with multiple recurrently altered pathways in HCC, suggesting that multiple pathways will need to be inhibited for any therapeutic method. mRNA processing is regulated by a complex RNA-protein network that is essential for the maintenance of homeostasis. THOC5, a member of mRNA export complex, has a role in less than 1% of mRNA processing, and is required for cell growth and differentiation, but not for cell survival in normal fibroblasts, hepatocytes and macrophages. In this report, we show that 50% depletion of THOC5 in human HCC cell lines Huh7 and HepG2 induced apoptosis. Transcriptome analysis using THOC5-depleted cells revealed that 396 genes, such as transmembrane BAX inhibitor motif containing 4 (TMBIM4), transmembrane emp24-like trafficking protein 10 (Tmed10) and D-tyrosyl-tRNA deacylase 2 (Dtd2) genes were downregulated in both cell lines. The depletion of one of these THOC5 target genes in Huh7 or HepG2 did not significantly induce cell death, suggesting that these may be fine tuners for HCC cell survival. However, the depletion of a combination of these genes synergistically increased the number of TUNEL (terminal deoxynucleotidyl transferase dUTP nick end labeling)-positive HCC. It must be noted that the depletion of these genes did not induce cell death in the hepatocyte cell line, THLE-2 cells. THOC5 expression was enhanced in 78% of cytological differentiation grading G2 and G3 tumor in primary HCC. Furthermore, the expression of a putative glycoprotein, Tmed10, is correlated to THOC5 expression level in primary HCCs, suggesting that this protein may be a novel biomarker for HCC. These data imply that the suppression of the multiple THOC5 target genes may represent a novel strategy for HCC therapy.