Hepatocellular carcinoma (HCC) is one of the most malignant tumor types and has a high incidence and mortality. Many miRNAs play important roles in the development of HCC. Identification of these miRNAs and their targets is increasingly urgent for a better understandingof miRNA function in both physiological and pathological contexts. Many studies have shown that the expression of let-7 is often downregulated in the process of tumorigenesis, suggesting that let-7 may participate in this process as an oncogene. Immunochemistry staining was used to observe the expression of let-7b in HCC tissues. A CCK-8 assay was employed to detect the role of let-7b in the proliferation of HCC cells. The cell cycle of HCC cells was examined by flow cytometry. BALB/c nu/nu mice were used to detect the tumorigenesis potential of HCC cells; western blot and real-time PCR were employed to observe the expression of p21 in HCC cells. In our previous studies investigating HCC tissue samples obtained from the national tissue samples bank of liver cancer in Eastern Hepatobiliary Surgery Hospital, we found one abnormal expression of miRNA (let-7b), which was significantly downregulated in HCC tissue. In the current work, we studied the relationship between let-7b and HCC to potentially provide invaluable information for developing novel therapeutic strategies for treating HCC. Based on our findings, let-7b expression was absent in HCC tumors, and its lower expression was associated with poor prognosis of HCC. In further experiments, we found that let-7b inhibited HCC cell proliferation through upregulation of p21. The results of our study suggested that let-7b might inhibit the proliferation of HCC cells by upregulating p21.

中文翻译：

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MicroRNA let-7b 通过上调 p21 在肝细胞癌中抑制细胞增殖。

肝细胞癌（HCC）是最恶性的肿瘤类型之一，发病率和死亡率都很高。许多 miRNA 在 HCC 的发生发展中起重要作用。为了更好地了解生理和病理背景下的 miRNA 功能，鉴定这些 miRNA 及其靶标变得越来越紧迫。许多研究表明let-7的表达在肿瘤发生过程中经常被下调，这表明let-7可能作为癌基因参与了这一过程。免疫化学染色观察肝癌组织中let-7b的表达。采用 CCK-8 测定法检测 let-7b 在 HCC 细胞增殖中的作用。流式细胞仪检测HCC细胞的细胞周期。BALB/c nu/nu小鼠用于检测HCC细胞的成瘤潜能；采用western blot和real-time PCR观察p21在HCC细胞中的表达。在我们之前研究从东部肝胆外科医院肝癌国家组织样本库获得的 HCC 组织样本的研究中，我们发现了一种 miRNA (let-7b) 的异常表达，它在 HCC 组织中显着下调。在目前的工作中，我们研究了 let-7b 与 HCC 之间的关系，以潜在地为开发治疗 HCC 的新治疗策略提供宝贵的信息。根据我们的研究结果，HCC 肿瘤中不存在 let-7b 表达，其较低的表达与 HCC 的不良预后相关。在进一步的实验中，我们发现 let-7b 通过上调 p21 抑制 HCC 细胞增殖。