Department of Oncology, the Fourth Affiliated Hospital, Anhui Medical University, Hefei, Anhui, 230022, China.
Department of General Surgery, the Fourth Affiliated Hospital, Anhui Medical University, Hefei, Anhui, 230022, China.
Cell Death Dis. 2021 Mar 26;12(4):326. doi: 10.1038/s41419-021-03494-1.
Hepatocellular carcinoma (HCC), commonly caused by liver fibrosis, is a global challenge with high morbidity. Activation of hepatic stellate cells (HSCs) contributes to hepatic fibrosis. Exosomes are small vesicles that play a significant role in cell-to-cell communication. Smoothened (SMO) is the key signal transducer for Hedgehog pathway. This study was designed to study the function and underlying mechanism of SMO in HSC activation. Functional assays including 5-Ethynyl-2´-deoxyuridine, colony formation, wound healing, transwell, and sphere formation assays disclosed the function of SMO. Western blot analysis of exosome biomarkers, immunofluorescence staining assay, electron microscope, and flow cytometry revealed the existence of exosomes. Bioinformatics analyses and mechanistic assays uncovered the interplays between RNAs. Nude mice xenograft model was established to evaluate HCC tumor growth. We uncovered that SMO was an oncogene in HCC cells and was low-expressed in quiescent HSCs. Then, SMO was upregulated in HSCs cultured with HCC cells-conditioned medium. Next, it was revealed that HCC cells-derived exosomes activated HSCs by transmitting SMO to HSCs. Subsequently, we recognized that microRNA let-7b host gene (MIRLET7BHG) served as the competing endogenous RNA against miR-330-5p to upregulate SMO. In turn, SMO induced hedgehog pathway to promote GLI family zinc finger 1 (Gli1), leading to transcriptional activation of MIRLET7BHG in activated HSCs. In summary, this study demonstrated that Gli1-induced MIRLET7BHG facilitated HCC by activating HSCs through exosomal SMO to stimulate hedgehog pathway, providing a new road for HCC treatment.
肝细胞癌（HCC）通常由肝纤维化引起，是一种具有高发病率的全球性挑战。肝星状细胞（HSCs）的激活导致肝纤维化。外泌体是一种在细胞间通讯中起重要作用的小囊泡。Smoothened（SMO）是 Hedgehog 通路的关键信号转导器。本研究旨在研究 SMO 在 HSC 激活中的功能和潜在机制。包括 5-乙炔基-2´-脱氧尿苷、集落形成、划痕愈合、Transwell 和球体形成测定在内的功能测定揭示了 SMO 的功能。外泌体生物标志物的 Western blot 分析、免疫荧光染色测定、电子显微镜和流式细胞术揭示了外泌体的存在。生物信息学分析和机制测定揭示了 RNA 之间的相互作用。裸鼠异种移植模型被建立来评估 HCC 肿瘤生长。我们发现 SMO 是 HCC 细胞中的癌基因，在静止的 HSCs 中低表达。然后，在 HCC 细胞条件培养基培养的 HSCs 中上调 SMO。接下来，揭示了 HCC 细胞衍生的外泌体通过将 SMO 传递给 HSCs 来激活 HSCs。随后，我们认识到 microRNA let-7b 宿主基因（MIRLET7BHG）作为竞争性内源 RNA，对抗 miR-330-5p 来上调 SMO。反过来，SMO 诱导 Hedgehog 途径促进 Gli 家族锌指蛋白 1（Gli1），导致激活的 HSCs 中转录激活 MIRLET7BHG。总之，本研究表明，Gli1 诱导的 MIRLET7BHG 通过外泌体 SMO 激活 Hedgehog 途径来激活 HSCs，从而促进 HCC，为 HCC 的治疗提供了新的途径。
