ZHX2 Inhibits SREBP1c-Mediated De Novo Lipogenesis in Hepatocellular Carcinoma via miR-24-3p

BACKGROUND: Hepatocellular carcinoma (HCC) is one of the leading causes of cancer-related death worldwide. Lipogenesis has been considered as a critical player in HCC initiation and progression. However, the underlying mechanism is still not fully understood. METHODS: ZHX2 overexpression and knockdown were introduced into HCC cell lines. BODIPY staining and D-Glucose- 13C6 labeled lipid mass spectrometry were involved to estimate lipogenesis in HCC cell lines. Colony formation and cell proliferation assays were used to determine HCC development. Hepatocytes specific Zhx2 knockout mice (Zhx2-KOhep) were included to induce spontaneous liver tumor. qRT-PCR, western blotting and dual luciferase assays were used to detect gene regulation. FINDINGS: Ectopic expression of ZHX2 significantly inhibited de novo lipogenesis in HCC cells and decreased expression of FASN, ACL, ACC and SCD1. In accordance, ZHX2 was negatively associated with SREBP1c, the master regulator of de novo lipogenesis, in HCC cell lines and human specimens. Further studies demonstrated that ZHX2 inhibited de novo lipogenesis and consequent HCC progression via repression of SREBP1c. Furthermore, treatment with SREBP1c inhibitor, fatostatin, dampened the spontaneous tumor formation in Zhx2-KOhep mice. Mechanically, ZHX2 transcriptionally increased expression of miR-24-3p, which targets on SREBP1c. INTERPRETATION: ZHX2 inhibits de novo lipogenesis in HCC cells by down-regulating the expression of SREBP1c via miR-24-3p, and further inhibits the development of HCC. These new findings may provide a new strategy for the treatment of HCC. FUNDING STATEMENT: This work was supported by grants from the National Science Foundation of China (Key project 81830017 and 81902443,81702647,81902051,81972819), Taishan Scholarship (No.tspd20181201), National Key Research and Development Program (2018YFE0126500), National Science Foundation for Distinguished Young Scholars of China (81425012), Shandong Provincial Key Innovation project (No.2018FYJH0503), Collaborative Innovation Center of Technology and Equipment for Biological Diagnosis and Therapy in Universities of Shandong, Key Research and Development Program of Shandong (2019GSF108238) . DECLARATION OF INTERESTS: All authors declare no potential conflicts of interest. ETHICS APPROVAL STATEMENT: The Medical Ethics Committee of Shandong University approved the use of human specimens in accordance with the Helsinki Declaration. All mice were housed under conditions free of specific pathogens and euthanized according to regulations established by the Animal Care Committee of Shandong University.