Bao Leilei, Zhang Mingjian, Han Shu, Zhan Yangyang, Guo Wenyuan, Teng Fei, Liu Fang, Guo Meng, Zhang Luding, Ding Guoshan, Wang Quanxiang
National Key Laboratory of Medical Immunology, Second Military Medical University, Shanghai, China.
Department of Pharmacy, No. 411 Hospital, Second Military Medical University, Shanghai, China.
Cell Physiol Biochem. 2018;47(5):2046-2055. doi: 10.1159/000491472. Epub 2018 Jul 3.
BACKGROUND/AIMS: Hepatocellular carcinoma (HCC) is one of the most common human malignant diseases in the world, and the mechanisms underlying HCC carcinogenesis and progression need further investigation. MicroRNAs play important roles in the development of cancer, and miR-500a is suggested to be deregulated in some types of cancer. However, the underlying molecular mechanisms of miR-500a in HCC remain unknown.
The expression of miR-500a in HCC was analyzed in The Cancer Genome Atlas (TCGA) database and examined in 33 pairs of HCC tissues and matched nontumor tissues. The correlation between miR-500a expression and prognosis of HCC patients was analyzed from the survival data in TCGA. The mechanism of miR-500a upregulation in HCC was detected using chromatin immunoprecipitation-quantitative real-time PCR. The roles of miR-500a in HCC development were examined using a cell counting kit-8 assay in vitro and growth of transplanted tumors in nude mice in vivo. Apoptosis of HCC was detected using Annexin V/propidium iodide staining. The expression of BH3-interacting death agonist (BID) protein was examined using western blot analysis.
miR-500a expression was upregulated in HCC tissues, and high miR-500a expression was significantly correlated with the poor prognosis of HCC patients. Histone modifications in the promoter region of miR-500a may be responsible for its increased expression. Inhibition of miR-500a in HCC cell lines significantly promoted apoptosis, as well as inhibiting the proliferation of HCC cells and growth of transplanted tumors in nude mice. miR-500a directly targeted the 3' untranslated region of BID mRNA, and inhibition of miR-500a-promoted apoptosis was almost completely abolished by the administration of ABT-199 via the BID-mitochondria pathway.
Our results suggest that histone modifications in the promoter region of miR-500a may be responsible for the increased expression of miR-500a in HCC, which promotes cancer progression by targeting BID, indicating that miR-500a may be a potential prognostic predictor and therapeutic target for HCC patients.
背景/目的：肝细胞癌（HCC）是全球最常见的人类恶性疾病之一，HCC发生和进展的潜在机制仍需进一步研究。微小RNA在癌症发展中发挥重要作用，且有研究表明miR-500a在某些类型的癌症中表达失调。然而，miR-500a在HCC中的潜在分子机制尚不清楚。
在癌症基因组图谱（TCGA）数据库中分析了miR-500a在HCC中的表达，并在33对HCC组织及相应的癌旁组织中进行检测。从TCGA的生存数据中分析miR-500a表达与HCC患者预后的相关性。采用染色质免疫沉淀-定量实时PCR检测HCC中miR-500a上调的机制。通过体外细胞计数试剂盒-8检测和体内裸鼠移植瘤生长实验，研究miR-500a在HCC发展中的作用。采用膜联蛋白V/碘化丙啶染色检测HCC细胞凋亡。通过蛋白质免疫印迹分析检测BH3相互作用死亡激动剂（BID）蛋白的表达。
miR-500a在HCC组织中表达上调，且高表达的miR-500a与HCC患者的不良预后显著相关。miR-500a启动子区域的组蛋白修饰可能是其表达增加的原因。抑制HCC细胞系中的miR-500a可显著促进细胞凋亡，同时抑制HCC细胞增殖和裸鼠移植瘤生长。miR-500a直接靶向BID mRNA的3'非翻译区，通过BID-线粒体途径给予ABT-199几乎完全消除了抑制miR-500a所促进的细胞凋亡。
我们的研究结果表明，miR-500a启动子区域的组蛋白修饰可能是导致HCC中miR-500a表达增加的原因，其通过靶向BID促进癌症进展，这表明miR-500a可能是HCC患者潜在的预后预测指标和治疗靶点。
