Lu Zhanping, Zhang Weiying, Gao Shan, Jiang Qiulei, Xiao Zelin, Ye Lihong, 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;468(1-2):8-13. doi: 10.1016/j.bbrc.2015.11.008. Epub 2015 Nov 6.
MicroRNAs acting as oncogenes or tumor suppressor genes play crucial roles in human cancers. Sphingosine kinase 1 (SPHK1) and its metabolite sphingosine 1-phosphate (S1P) contribute to tumor angiogenesis. We have reported that the down-regulation of miR-506 targeting YAP mRNA results in the hepatocarcinogenesis. In the present study, we report a novel function of miR-506, which suppresses tumor angiogenesis through targeting SPHK1 mRNA in liver cancer. Bioinformatics analysis showed that miR-506 might target 3'-untranslated region (3'UTR) of SPHK1 mRNA. Then, we validated that by luciferase reporter gene assays. MiR-506 was able to reduce the expression of SPHK1 at the levels of mRNA and protein using reverse transcription-polymerase chain reaction and Western blot analysis in hepatoma HepG2 cells. Functionally, human umbilical vein endothelial cell (HUVEC) tube formation assays demonstrated that the forced miR-506 expression remarkably inhibited the production of S1P in the supernatant of hepatoma cells. The supernatant resulted in the inhibition of tumor angiogenesis. Interestingly, the supernatant with overexpression of SPHK1 could rescue the inhibition of angiogenesis of liver cancer mediated by miR-506. Anti-miR-506 increased the production of S1P in the supernatant of hepatoma cells, but the supernatant with silencing of SPHK1 abolished anti-miR-506-induced acceleration of tumor angiogenesis. Clinically, we observed that the levels of miR-506 were negatively related to those of SPHK1 mRNA in liver cancer tissues. Thus, we conclude that miR-506 depresses the angiogenesis of liver cancer through targeting 3'UTR of SPHK1 mRNA. Our finding provides new insights into the mechanism of tumor angiogenesis.
作为癌基因或肿瘤抑制基因的微小RNA在人类癌症中发挥着关键作用。鞘氨醇激酶1（SPHK1）及其代谢产物鞘氨醇-1-磷酸（S1P）有助于肿瘤血管生成。我们已报道，靶向YAP mRNA的miR-506下调会导致肝癌发生。在本研究中，我们报道了miR-506的一种新功能，即通过靶向肝癌中的SPHK1 mRNA来抑制肿瘤血管生成。生物信息学分析表明，miR-506可能靶向SPHK1 mRNA的3'-非翻译区（3'UTR）。然后，我们通过荧光素酶报告基因检测验证了这一点。使用逆转录-聚合酶链反应和蛋白质印迹分析，miR-506能够在肝癌HepG2细胞的mRNA和蛋白质水平上降低SPHK1的表达。在功能上，人脐静脉内皮细胞（HUVEC）管形成试验表明，强制表达miR-506可显著抑制肝癌细胞上清液中S1P的产生。该上清液导致肿瘤血管生成受到抑制。有趣的是，过表达SPHK1的上清液可以挽救由miR-506介导的肝癌血管生成抑制。抗miR-506增加了肝癌细胞上清液中S1P的产生，但沉默SPHK1的上清液消除了抗miR-506诱导的肿瘤血管生成加速。临床上，我们观察到肝癌组织中miR-506的水平与SPHK1 mRNA的水平呈负相关。因此，我们得出结论，miR-506通过靶向SPHK1 mRNA的3'UTR抑制肝癌血管生成。我们的发现为肿瘤血管生成机制提供了新的见解。
