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

Abstract

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.