LIM homeobox-2 suppresses hallmarks of adult and pediatric liver cancers by inactivating MAPK/ERK and Wnt/beta-catenin pathways

Introduction: Hepatocellular carcinoma and hepatoblastoma are two liver cancers characterized by gene deregulations, chromosomal rearrangements, and mutations in Wnt/beta-catenin (Wnt) pathway-related genes. LHX2, a transcriptional factor member of the LIM homeobox gene family, has important functions in embryogenesis and liver development. LHX2 is oncogenic in many solid tumors and leukemia but its role in liver cancer is unknown. Methods: We analyzed the expression of LHX2 in hepatocellular carcinoma and hepatoblastoma samples using various transcriptomic datasets and biological samples. The role of LHX2 was studied using lentiviral transduction, in vitro cell-based assays (growth, migration, senescence, apoptosis), molecular approaches (phospho-kinase arrays, RNA-seq), bioinformatics and two in vivo models in chicken and Xenopus embryos. Results: We found a strong connection between LHX2 down-regulation and Wnt activation in these two liver cancers. In hepatoblastoma, LHX2 downregulation correlated with multiple poor outcome parameters including higher patient age, intermediate- and high-risk tumors and low patients’ survival. Forced expression of LHX2 reduced the proliferation, migration and survival of hepatoma cells in vitro through the inactivation of MAPK/ERK and Wnt signals. In vivo, LHX2 impeded the development of tumors in chick embryos and repressed the Wnt pathway in Xenopus embryos. RNA-sequencing data and bioinformatic analyses confirmed the deregulation of many biological functions and molecular processes associated with cell migration, cell survival and liver carcinogenesis in LHX2-expressing hepatoma cells. At a mechanistic level, LHX2 mediated the disassembling of beta-catenin/T-cell factor 4 complex and induced expression of multiple inhibitors of Wnt (e.g. TLE/Groucho) and MAPK/ERK (e.g. DUSPs) pathways. Conclusion: Collectively, our findings demonstrate a tumor suppressive function of LHX2 in adult and pediatric liver cancers.

Inhibiting Effects of Down-regulating of Fascin 1 on Proliferation and Migration in Hepatoma Cells

Objective: To investigate the inhibiting effects of fascin 1 gene knock-down on the proliferation and migration of hepatoma cells by means of small interfering RNA (siRNA).Methods: SiRNA targeting fascin 1 gene (si-fascin) and non-specific sequence siRNA (si-NC）were constructed and transfected into human hepatoma cell lines (HepG2 and Huh7) to down-regulate the expression of fascin 1. RT-qPCR, Western blotting, and Immunofluorescence technique were used to evaluate the efficiency of si-fascin. The proliferation and migration of cells were detected by MTT method and Transwell experiments, and the protein expression of genes related to proliferation and migration in cells were detected by Western blotting. The apoptosis and pseudopodia formation of cells were observed under scanning electron microscope (SEM).Results: Compared with human normal liver cells (LO2), the expressions of fascin 1 mRNA and protein were significantly higher in HepG2 and Huh7 cells. The expression of fascin 1 was overall inhibited in HepG2 and Huh7 cells transfected by the constructed four si-fascins, among which, fascin_siR3 had the highest inhibitory efficiency, therefore was selected in this study. In HepG2 and Huh7 cells transfected by si-fascin significant knock-down target gene expression, while reducing cell proliferation, migration and the formation of pseudopods, and causes reduced protein expression associated with proliferation and migration. Conclusion: This study further confirmed that fascin 1 gene has the function of promoting hepatoma cells proliferation and migration, suggesting that downregulating the expression of fascin 1 in hepatoma cells may be one of the strategies to intervene in liver cancer.

The inflammatory accumulation of lipids and ROS in human Nrf1α-deficient hepatoma cells is ameliorated by 2-bromopalmitate

Since Nrf1 and Nrf2 are essential for regulating the lipid metabolism pathways, their dysregulation was also shown to be critically involved in the non-controllable inflammatory pathology into cancer development. However, it is unknown that the interaction between Nrf1 and Nrf2 in the regulation of lipid metabolism, especially in hepatoma cells. Here, we have further explored the molecular mechanisms underlying their distinct regulation of lipid metabolism, by comparative analysis of changes in those lipid metabolism-related genes in Nrf1α-/- and/or Nrf2-/- cell lines relative to wild-type controls. The results revealed that loss of Nrf1 leads to disordered lipid metabolism; its lipid synthesis pathway was up-regulated by JNK-Nrf2-AP1 signaling, while its lipid decomposition pathway was down-regulated by the nuclear receptor PPAR-PGC1 signaling, resulting in severe accumulation of lipids as deposited in lipid droplets. By contrast, knockout of Nrf2 gave rise to decreases in lipid synthesis and uptake capacity. These demonstrate that Nrf1 and Nrf2 contribute to significant differences in the cellular lipid metabolism regulatory profiles and relevant pathological responses. Further experiments unraveled that lipid deposition in Nrf1α-/- cells was resulted from CD36 upregulation by activating the PI3K-AKT-mTOR pathway, leading to induction of the inflammatory response. Following treatment of Nrf1[alpha]-/- cells with 2-bromopalmitate (2BP), it enabled the yield of lipid droplets to be strikingly alleviated, as companied by substantial abolishment of CD36 and critical inflammatory cytokines. Such Nrf1[alpha]-/--led inflammatory accumulation of lipids and ROS was significantly ameliorated by 2BP. Overall, this study provides a potential strategy for cancer prevention and treatment by precision targeting of Nrf1, Nrf2, or both.