Sun Jin, Li Yingnan, Shi Mengjiao, Tian Hongwei, Li Jun, Zhu Kai, Guo Ying, Mu Yanhua, Geng Jing, Li Zongfang
National-Local Joint Engineering Research Center of Biodiagnostics and Biotherapy, Xi'an Jiaotong University, Xi'an, Shaanxi, People's Republic of China.
Shaanxi Provincial Clinical Research Center for Hepatic & Splenic Diseases, the Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi, People's Republic of China.
J Hepatocell Carcinoma. 2023 Jul 27;10:1237-1256. doi: 10.2147/JHC.S416946. eCollection 2023.
HOX cluster-embedded long noncoding RNAs (HOX-lncRNAs) have been shown to be tightly related to hepatocellular carcinoma (HCC). However, the potential biological roles and underlying molecular mechanism of HOX-lncRNAs in HCC largely remains to be elucidated.
The expression signature of eighteen HOX-lncRNAs in HCC cell lines were measured by qRT-PCR. HOXD-AS2 expression and its clinical significance in HCC was investigated by bioinformatics analysis utilizing the TCGA data. Subcellular localization of HOXD-AS2 in HCC cells was observed by RNA-FISH. Loss‑of‑function experiments in vitro and in vivo were conducted to probe the roles of HOXD-AS2 in HCC. Potential HOXD-AS2-controlled genes and signaling pathways were revealed by RNA-seq. Rescue experiments were performed to validate that SMYD3 mediates HOXD-AS2 promoting HCC progression. The positive feedback loop of HOXD-AS2 and SMYD3 was identified by luciferase reporter assay and ChIP-qPCR.
HOXD-AS2 was dramatically elevated in HCC, and its up-regulation exhibited a positive association with aggressive clinical features (T stage, pathologic stage, histologic grade, AFP level, and vascular invasion) and unfavorable prognosis of HCC patients. HOXD-AS2 was distributed both in the nucleus and the cytoplasm of HCC cells. Knockdown of HOXD-AS2 restrained the proliferation, migration, invasion of HCC cells in vitro, as well as tumor growth in subcutaneous mouse model. Transcriptome analysis demonstrated that SMYD3 expression and activity of MEK/ERK pathway were impaired by silencing HOXD-AS2 in HCC cells. Rescue experiments revealed that SMYD3 as downstream target mediated oncogenic functions of HOXD-AS2 in HCC cells through altering the expression of cyclin B1, cyclin E1, MMP2 as well as the activity of MEK/ERK pathway. Additionally, HOXD-AS2 was uncovered to be positively regulated at transcriptional level by its downstream gene of SMYD3.
HOXD-AS2, a novel oncogenic HOX-lncRNA, facilitates HCC progression by forming a positive feedback loop with SMYD3 and activating the MEK/ERK pathway.
已证明HOX基因簇嵌入的长链非编码RNA（HOX-lncRNAs）与肝细胞癌（HCC）密切相关。然而，HOX-lncRNAs在HCC中的潜在生物学作用和潜在分子机制在很大程度上仍有待阐明。
通过qRT-PCR检测18种HOX-lncRNAs在肝癌细胞系中的表达特征。利用TCGA数据通过生物信息学分析研究HOXD-AS2在HCC中的表达及其临床意义。通过RNA-FISH观察HOXD-AS2在肝癌细胞中的亚细胞定位。进行体外和体内功能缺失实验以探究HOXD-AS2在HCC中的作用。通过RNA-seq揭示潜在的HOXD-AS2调控基因和信号通路。进行挽救实验以验证SMYD3介导HOXD-AS2促进HCC进展。通过荧光素酶报告基因检测和ChIP-qPCR鉴定HOXD-AS2和SMYD3的正反馈环。
HOXD-AS2在HCC中显著升高，其上调与侵袭性临床特征（T分期、病理分期、组织学分级、AFP水平和血管侵犯）以及HCC患者的不良预后呈正相关。HOXD-AS2分布于肝癌细胞的细胞核和细胞质中。敲低HOXD-AS2可抑制体外肝癌细胞的增殖、迁移和侵袭，以及皮下小鼠模型中的肿瘤生长。转录组分析表明，沉默肝癌细胞中的HOXD-AS2会损害SMYD3的表达和MEK/ERK通路的活性。挽救实验表明，SMYD3作为下游靶点，通过改变细胞周期蛋白B1、细胞周期蛋白E1、MMP2的表达以及MEK/ERK通路的活性，介导HOXD-AS2在肝癌细胞中的致癌功能。此外，发现HOXD-AS2在转录水平上受到其下游基因SMYD3的正调控。
HOXD-AS2是一种新型致癌HOX-lncRNA，通过与SMYD3形成正反馈环并激活MEK/ERK通路促进HCC进展。
