Zhang Weiying, Lu Zhanping, Gao Yuen, Ye Lihong, Song Tianqiang, Zhang Xiaodong
State Key Laboratory of Medicinal Chemical Biology, Department of Cancer Research, College of Life Sciences, Nankai University, Tianjin, PR China.
State Key Laboratory of Medicinal Chemical Biology, Department of Biochemistry, College of Life Sciences, Nankai University, Tianjin, PR China.
Biochem Biophys Res Commun. 2015 May 8;460(3):793-8. doi: 10.1016/j.bbrc.2015.03.108. Epub 2015 Mar 28.
Accumulating evidence indicates that microRNAs are able to act as oncogenes or tumor suppressor genes in human cancer. We previously reported that miR-520b was down-regulated in hepatocellular carcinoma (HCC) and its deregulation was involved in hepatocarcinogenesis. In the present study, we report that miR-520b suppresses cell proliferation in HCC through targeting the ten-eleven translocation 1 (TET1) mRNA. Notably, we identified that miR-520b was able to target 3'-untranslated region (3'UTR) of TET1 mRNA by luciferase reporter gene assays. Then, we revealed that miR-520b was able to reduce the expression of TET1 at the levels of mRNA and protein using reverse transcription-polymerase chain reaction and Western blotting analysis. In terms of function, 5-ethynyl-2-deoxyuridine (EdU) incorporation and colony formation assays demonstrated that the forced miR-520b expression remarkably inhibited proliferation of hepatoma cells, but TET1 overexpression could rescue the inhibition of cell proliferation mediated by miR-520b. Furthermore, anti-miR-520b enhanced proliferation of hepatoma cells, whereas silencing of TET1 abolished anti-miR-520b-induced acceleration of cell proliferation. Then, we validated that the expression levels of miR-520b were negatively related to those of TET1 mRNA in clinical HCC tissues. Thus, we conclude that miR-520b depresses proliferation of liver cancer cells through targeting 3'UTR of TET1 mRNA. Our finding provides new insights into the mechanism of hepatocarcinogenesis.
越来越多的证据表明，微小RNA在人类癌症中可作为癌基因或肿瘤抑制基因发挥作用。我们之前报道过，miR-520b在肝细胞癌（HCC）中表达下调，其失调与肝癌发生有关。在本研究中，我们报道miR-520b通过靶向十一-易位酶1（TET1）mRNA抑制HCC细胞增殖。值得注意的是，我们通过荧光素酶报告基因实验确定miR-520b能够靶向TET1 mRNA的3'-非翻译区（3'UTR）。然后，我们通过逆转录-聚合酶链反应和蛋白质印迹分析发现，miR-520b能够在mRNA和蛋白质水平降低TET1的表达。在功能方面，5-乙炔基-2'-脱氧尿苷（EdU）掺入实验和集落形成实验表明，强制表达miR-520b可显著抑制肝癌细胞增殖，但TET1过表达可挽救miR-520b介导的细胞增殖抑制作用。此外，抗miR-520b可增强肝癌细胞增殖，而沉默TET1可消除抗miR-520b诱导的细胞增殖加速。然后，我们验证了临床HCC组织中miR-520b的表达水平与TET1 mRNA的表达水平呈负相关。因此，我们得出结论，miR-520b通过靶向TET1 mRNA的3'UTR抑制肝癌细胞增殖。我们的发现为肝癌发生机制提供了新的见解。
