Wei Qing, Liu Guoman, Huang Zihua, Huang Yanyan, Huang Lizheng, Huang Zheng, Wu Xianjian, Wei Huamei, Pu Jian
Graduate College of Youjiang Medical University for Nationalities, Baise, Guangxi, 533099, People's Republic of China.
Department of Hepatobiliary Surgery, Affiliated Hospital of Youjiang Medical University for Nationalities, Baise, Guangxi, 533000, People's Republic of China.
J Hepatocell Carcinoma. 2023 Jul 5;10:1019-1035. doi: 10.2147/JHC.S408800. eCollection 2023.
Hepatocellular carcinoma (HCC) is the predominant histological type of primary liver cancer, which ranks sixth among the most common human tumors. Tumor-associated macrophages (TAMs) are an important component of tumor microenvironment (TME) and the M2 macrophage polarization substantially contributes to tumor growth and metastasis. Long non-coding RNA (lncRNA) MEG3 was reported to restrain HCC development. However, whether MEG3 regulates macrophage phenotypic polarization in HCC remains unclear.
Bone marrow derived macrophages (BMDMs) were treated with LPS/IFNγ and IL4/IL13 to induce the M1 and M2 macrophage polarization, respectively. M2-polarized BMDMs were simultaneously transfected with adenovirus vector overexpressing MEG3 (Adv-MEG3). Subsequently, M2-polarized BMDMs were cultured for 24 h with serum-free medium, the supernatants of which were harvested as conditioned medium (CM). HCC cell line Huh7 was cultured with CM for 24 h. F4/80CD68 and F4/80CD206 cell percentages in M1-and M2-polarized BMDMs were calculated using flow cytometry. Huh7 cell migration, invasion and angiogenesis were determined via Transwell assay and tube formation experiment. Nude mice were implanted with Huh7 cells and Adv-MEG3-transfected M2-polarizd BMDMs, and tumor growth and M2 macrophage polarization markers were assessed. The binding between miR-145-5p and MEG3 or disabled-2 (DAB2) was verified by luciferase reporter assay.
MEG3 presented lower expression in HCC tissues than in normal controls, and low expression of MEG3 was correlated to poorer prognosis of HCC patients. MEG3 expression was enhanced during LPS/IFNγ-induced M1 polarization, but was reduced during IL4/IL13-induced M2 polarization. MEG3 overexpression inhibited the expression of M2 polarization markers in both M2-polarized BMDMs and mice. Mechanically, MEG3 bound with miR-145-5p to regulate DAB2 expression. Overexpressing MEG3 suppressed M2 polarization-induced HCC cell metastasis and angiogenesis by upregulating DAB2 and inhibited in vivo tumor growth.
LncRNA MEG3 curbs HCC development by repressing M2 macrophage polarization via miR-145-5p/DAB2 axis.
肝细胞癌（HCC）是原发性肝癌的主要组织学类型，在最常见的人类肿瘤中排名第六。肿瘤相关巨噬细胞（TAM）是肿瘤微环境（TME）的重要组成部分，M2巨噬细胞极化在很大程度上促进肿瘤生长和转移。据报道，长链非编码RNA（lncRNA）MEG3可抑制HCC的发展。然而，MEG3是否调节HCC中巨噬细胞的表型极化仍不清楚。
用脂多糖/干扰素γ（LPS/IFNγ）和白细胞介素4/白细胞介素13（IL4/IL13）分别处理骨髓来源的巨噬细胞（BMDM），以诱导M1和M2巨噬细胞极化。将过表达MEG3的腺病毒载体（Adv-MEG3）同时转染至M2极化的BMDM。随后，将M2极化的BMDM在无血清培养基中培养24小时，收集其上清液作为条件培养基（CM）。将肝癌细胞系Huh7与CM共培养24小时。使用流式细胞术计算M1和M2极化的BMDM中F4/80⁺CD68⁺和F4/80⁺CD206⁺细胞百分比。通过Transwell实验和管形成实验测定Huh7细胞的迁移、侵袭和血管生成。将Huh7细胞和Adv-MEG3转染的M2极化BMDM接种到裸鼠体内，评估肿瘤生长和M2巨噬细胞极化标志物。通过荧光素酶报告基因实验验证miR-145-5p与MEG3或Disabled-2（DAB2）之间的结合。
MEG3在HCC组织中的表达低于正常对照，MEG3低表达与HCC患者较差的预后相关。在LPS/IFNγ诱导的M1极化过程中MEG3表达增强，但在IL4/IL13诱导的M2极化过程中MEG3表达降低。MEG3过表达抑制了M2极化的BMDM和小鼠中M2极化标志物的表达。机制上，MEG3与miR-145-5p结合以调节DAB2表达。过表达MEG3通过上调DAB2抑制M2极化诱导的肝癌细胞转移和血管生成，并抑制体内肿瘤生长。
LncRNA MEG3通过miR-145-5p/DAB2轴抑制M2巨噬细胞极化来抑制HCC的发展。
