Department of General Surgery, Second Affiliated Hospital of Nanchang University, Nanchang, 330000, China.
Jiangxi Province Key Laboratory of Molecular Medicine, Second Affiliated Hospital of Nanchang University, Nanchang, 330000, China.
J Transl Med. 2024 Oct 10;22(1):918. doi: 10.1186/s12967-024-05690-x.
Research has elucidated that homeobox B9 (HOXB9), an important transcriptional activator, plays a pivotal role in promoting the invasion and metastasis of hepatocellular carcinoma (HCC) cells. However, the mechanism by which HOXB9 promotes the invasion and metastasis of HCC cells is incompletely understood and needs further exploration.
HOXB9 and snail family transcriptional repressor 2 (SNAI2) expression were analyzed using qRT-PCR and western blotting. The invasion and metastasis of hepatocellular carcinoma (HCC) cells were investigated using in vitro and in vivo assays. The H3K27me3 enrichment and HOXB9 interaction with microRNA 203a (MIR203A) or SNAI2 were detected using ChIP-qPCR. Transcriptional activities of SNAI2 and MIR203A promoter were detected using dual-luciferase reporter assays. Co-IP and GST pull-down assays were performed to confirm the binding between HOXB9 and EZH2.
HOXB9 and SNAI2 were highly expressed in HCC tissues and their expression was positively intercorrelated and associated with poor prognosis in patients with HCC. In vitro and in vivo experiments confirmed that HOXB9 can upregulate the expression of SNAI2 to promote the invasion and metastasis of HCC cells. Furthermore, HOXB9 elevated SNAI2 expression by inhibiting MIR203A expression, a tumor suppressor gene, in HCC cells. Mechanistically, HOXB9 recruited enhancer of zeste 2 polycomb repressive complex 2 subunit (EZH2) through interaction with its WD-binding domain, which increased EZH2-mediated histone H3 lysine 27 trimethylation (H3K27me3) at the MIR203A promoter region, in turn repressing the transcriptional activity and expression of MIR203A and consequently increasing the SNAI2 level in HCC cells. Finally, empirical evidence from in vitro and in vivo studies confirmed that mitigation of the HOXB9-mediated enhancement of epigenetic silencing of MIR203A inhibited SNAI2 expression, impeding the invasion and metastasis of HCC cells.
Our study reveals a novel mechanism by which HOXB9 promotes the invasion and metastasis of HCC cells and expands the understanding of the function of HOXB9 in tumor progression and provides a novel therapeutic strategy for curtailing HCC invasion and metastasis.
研究已经阐明，同源盒基因 B9（HOXB9）作为一种重要的转录激活因子，在促进肝细胞癌（HCC）细胞的侵袭和转移中发挥着关键作用。然而，HOXB9 促进 HCC 细胞侵袭和转移的机制尚不完全清楚，需要进一步探索。
使用 qRT-PCR 和 Western blot 分析 HOXB9 和蜗牛家族转录阻遏物 2（SNAI2）的表达。使用体外和体内实验研究肝细胞癌（HCC）细胞的侵袭和转移。使用 ChIP-qPCR 检测 H3K27me3 富集和 HOXB9 与 microRNA 203a（MIR203A）或 SNAI2 的相互作用。使用双荧光素酶报告基因检测试剂盒检测 SNAI2 和 MIR203A 启动子的转录活性。进行 Co-IP 和 GST 下拉实验以确认 HOXB9 与 EZH2 的结合。
HOXB9 和 SNAI2 在 HCC 组织中高表达，其表达呈正相关，与 HCC 患者的不良预后相关。体外和体内实验证实，HOXB9 可通过上调 SNAI2 的表达来促进 HCC 细胞的侵袭和转移。此外，HOXB9 通过抑制 HCC 细胞中肿瘤抑制基因 MIR203A 的表达来上调 SNAI2 的表达。机制上，HOXB9 通过与 WD 结合域相互作用，招募增强子结合锌指蛋白 2 多梳抑制复合物 2 亚基（EZH2），增加 MIR203A 启动子区域的组蛋白 H3 赖氨酸 27 三甲基化（H3K27me3），进而抑制 MIR203A 的转录活性和表达，从而增加 HCC 细胞中的 SNAI2 水平。最后，体外和体内研究的实验证据证实，减轻 HOXB9 介导的 MIR203A 表观遗传沉默增强可抑制 SNAI2 的表达，从而阻止 HCC 细胞的侵袭和转移。
本研究揭示了 HOXB9 促进 HCC 细胞侵袭和转移的新机制，扩展了对 HOXB9 在肿瘤进展中的功能的认识，并为抑制 HCC 侵袭和转移提供了新的治疗策略。
