NHC Key Laboratory of Hormones and Development, Tianjin Key Laboratory of Metabolic Diseases, Chu Hsien-I Memorial Hospital & Tianjin Institute of Endocrinology, Tianjin Medical University, Tianjin, China.
Department of Hepatobiliopancreatic Surgery, The Affiliated Cancer Hospital of Zhengzhou University & Henan Cancer Hospital, Zhengzhou, China.
Cell Mol Gastroenterol Hepatol. 2024;18(2):101348. doi: 10.1016/j.jcmgh.2024.04.005. Epub 2024 Apr 30.
BACKGROUND & AIMS: Metabolic dysfunction-associated steatotic liver disease (MASLD) is a dynamic chronic liver disease closely related to metabolic abnormalities such as diabetes and obesity. MASLD can further progress to metabolic dysfunction-associated steatohepatitis (MASH), fibrosis, cirrhosis, and even hepatocellular carcinoma (HCC). However, the mechanisms underlying the progression of MASLD and further progression to liver fibrosis and liver cancer are unknown.
In this study, we performed transcriptome analysis in livers from mice with MASLD and found suppression of a potential anti-oncogene, RAS association domain protein 4 (RASSF4). RASSF4 expression levels were measured in liver or tumor tissues of patients with MASH or HCC, respectively. We established RASSF4 overexpression and knockout mouse models. The effects of RASSF4 were evaluated by quantitative polymerase chain reaction, Western blotting, histopathological analysis, wound healing assays, Transwell assays, EdU incorporation assays, colony formation assays, sorafenib sensitivity assays, and tumorigenesis assays.
RASSF4 was significantly down-regulated in MASH and HCC samples. Using liver-specific RASSF4 knockout mice, we demonstrated that loss of hepatic RASSF4 exacerbated hepatic steatosis and fibrosis. In contrast, RASSF4 overexpression prevented steatosis in MASLD mice. In addition, RASSF4 in hepatocytes suppressed the activation of hepatic stellate cells (HSCs) by reducing transforming growth factor beta secretion. Moreover, we found that RASSF4 is an independent prognostic factor for HCC. Mechanistically, we found that RASSF4 in the liver interacts with MST1 to inhibit YAP nuclear translocation through the Hippo pathway.
These findings establish RASSF4 as a therapeutic target for MASLD and HCC.
代谢相关脂肪性肝病（MASLD）是一种与糖尿病和肥胖等代谢异常密切相关的动态慢性肝病。MASLD可进一步进展为代谢相关性脂肪性肝炎（MASH）、纤维化、肝硬化，甚至肝细胞癌（HCC）。然而，MASLD 进展及进一步进展为肝纤维化和肝癌的机制尚不清楚。
本研究通过对 MASLD 小鼠肝脏进行转录组分析，发现潜在抑癌基因 RAS 相关结构域蛋白 4（RASSF4）受到抑制。分别检测了 MASH 或 HCC 患者肝或肿瘤组织中 RASSF4 的表达水平。我们建立了 RASSF4 过表达和敲除小鼠模型。通过定量聚合酶链反应、Western blot、组织病理学分析、划痕愈合实验、Transwell 实验、EdU 掺入实验、集落形成实验、索拉非尼敏感性实验和肿瘤发生实验来评估 RASSF4 的作用。
RASSF4 在 MASH 和 HCC 样本中显著下调。使用肝特异性 RASSF4 敲除小鼠，我们证明肝 RASSF4 的缺失加剧了肝脂肪变性和纤维化。相反，RASSF4 的过表达可预防 MASLD 小鼠的脂肪变性。此外，肝细胞中的 RASSF4 通过减少转化生长因子β的分泌来抑制肝星状细胞（HSCs）的激活。此外，我们发现 RASSF4 是 HCC 的一个独立预后因素。在机制上，我们发现肝脏中的 RASSF4 与 MST1 相互作用，通过 Hippo 通路抑制 YAP 的核易位。
这些发现确立了 RASSF4 作为 MASLD 和 HCC 的治疗靶点。
