Liver cancer stem cell (CSC) self-renewal and tumorigenesis are important causes of hepatocellular carcinoma (HCC) recurrence. We purposed to investigate the function of long noncoding RNA small nucleolar RNA host gene 9 (SNHG9) in liver CSC self-renewal and tumorigenesis in this study. Flow cytometry was carried out to separate CD133⁺ Populations and CD133⁻ Populations from HCC cell lines. A combination of CD133⁺ cells and Matrigel matrix was subcutaneously injected to create the NOD-SCID mouse xenograft tumor model. Colony formation test and spheroids formation assay were carried out to clarify the impact of SNHG9 on the self-renewal of liver CSCs. RNA immunoprecipitation, RNA-pull down, and chromatin immunoprecipitation were performed on CD133⁺ cells to elucidate the mechanism of SNHG9 regulating PTEN expression. We found that SNHG9 was highly expressed in HCC clinical samples, HCC cells, and CD133⁺ cells. In vitro, interference with SNHG9 prevented the formation of colonies and spheroids in liver CSC cells and primary HCC cells. In vivo, interference with SNHG9 reduced the tumor volume and weight. SNHG9 could bind to EZH2, and SNHG9 interference suppressed EZH2 recruitment and H3K27me3 levels in the PTEN promoter region. In addition, SNHG9 inhibition promoted PTEN expression while having little impact on EZH2 levels. Interference with SNHG9 inhibited liver CSC self-renewal and tumorigenesis by up-regulating PTEN levels. In conclusion, by binding to EZH2, SNHG9 down-regulated PTEN levels, promoting liver CSC self-renewal and tumor formation, and exacerbating HCC progression.

肝癌干细胞（CSC）的自我更新和肿瘤发生是肝细胞癌（HCC）复发的重要原因。本研究旨在探讨长链非编码RNA小核仁RNA宿主基因9（SNHG9）在肝脏CSC自我更新和肿瘤发生中的功能。进行流式细胞术以从 HCC 细胞系中分离 CD133 ⁺群体和 CD133 ^-群体。^{皮下注射CD133 +}细胞和Matrigel基质的组合以创建NOD-SCID小鼠异种移植肿瘤模型。通过集落形成实验和球体形成实验来阐明SNHG9对肝脏CSC自我更新的影响。^{对 CD133 +}细胞进行 RNA 免疫沉淀、RNA-pull down 和染色质免疫沉淀，以阐明 SNHG9 调节 PTEN 表达的机制。我们发现SNHG9在HCC临床样本、HCC细胞和CD133 ⁺细胞中高表达。在体外，干扰 SNHG9 可阻止肝脏 CSC 细胞和原发性 HCC 细胞中集落和球体的形成。在体内，干扰 SNHG9 可以减少肿瘤的体积和重量。SNHG9 可以与 EZH2 结合，并且 SNHG9 干扰抑制了 PTEN 启动子区域中的 EZH2 募集和 H3K27me3 水平。此外，SNHG9 抑制促进了 PTEN 表达，而对 EZH2 水平影响很小。干扰 SNHG9 通过上调 PTEN 水平抑制肝脏 CSC 自我更新和肿瘤发生。总之，SNHG9通过与EZH2结合，下调PTEN水平，促进肝脏CSC自我更新和肿瘤形成，并加剧HCC进展。