Project description:Background & Aims: Hepatocyte nuclear factor 4A (HNF4A) is a master transcription factor (TF) in hepatocytes that regulates metabolism and differentiation. The mechanism of HNF4A in cancer progression remains unclear due to conflicting results observed in numerous studies. We aimed to address the roles of HNF4A in hepatocellular carcinoma (HCC). Methods: We established the HNF4A overexpression and knocking-down stable cells in HCCLM3 and Huh7, and compared the effects of HNF4A on HCC cells in different glucose supply conditions in vitro and in vivo. Pathway inhibitors treatment and phosphatase activity comparisons were performed for signaling pathway analysis. Gene levels in HCC tissues and the clinical information were collected from TCGA for survival analysis. Multiomics approaches including proteomics, TFRE and ChIP-seq were applied to identify HNF4A target genes. Rescue experiments were performed to verify the functions of the potential target genes. Results: We found HNF4A exhibited tumor-suppressive effects on proliferation and migration of HCC cells in glucose-sufficient conditions but tumor-promotive effects in glucose-insufficient conditions. This diverse functionality of HNF4A was dependent upon the AMPK pathway activity. Similarly, the prognosis predicted by HNF4A was also correlated with AMPKa expression level in HCC patients. The potential HNF4A target genes, including NEDD4 and RPS6KA2, are involved in the diverse functionality of HNF4A in response to AMPK activity status. Conclusions: The glucose supply status could be the potential decisive factor to determine functions of HNF4A on HCC cells. The switch of HNF4A between oncogene and tumor suppressor was determined by AMPK activation status, which was correlated with glucose levels.
Project description:Circular RNAs (circRNAs) have emerged as crucial regulators in physiology and human diseases. However, evolutionarily conserved circRNAs with potent functions in cancers are rarely reported. Here, we identified a mammalian conserved circRNA circLARP2 that played critical roles in hepatocellular carcinoma (HCC). With clinical specimens, we found that patients with high circLARP2 levels in HCC had advanced prognostic stage and poor overall survival. CircLARP2 facilitated HCC metastasis and lipid accumulation in HCC cell lines. CircLARP2 was one of the rare ones that were identified in HCC metastasis and conserved in mammals, which enabled further studies with animal models. CircLARP2-deficient mice exhibited reduced metastasis and less lipid accumulation in an induced HCC model. We provided lines of evidence at molecular, cellular, and whole organismal levels, to support that circLARP2 functioned as a protein sponge of AUF1. CircLARP2 sequestered AUF1 from binding to LKB1 mRNA, which led to decreased LKB1 mRNA stability and lower LKB1 protein levels. LKB1 as a kinase promoted the phosphorylation of AMPK and then the phosphorylation of ACC, the rate limiting enzyme of fatty acid synthesis. Knockdown of Lkb1 with AAV8-shLkb1 in mice HCC model also proved that Lkb1 was a key element in the regulation. Through this AUF1-LKB1-AMPK-ACC pathway, circLARP2 promoted HCC metastasis and lipid accumulation.
Project description:TFEB and TFE3 are transcriptional regulators of the innate immune response, but the mechanisms regulating their activation upon pathogen infection are poorly elucidated. Using C. elegans and mammalian models, we report that the master metabolic modulator 5'-AMP-activated protein kinase (AMPK) and its negative regulator Folliculin (FLCN) act upstream of TFEB/TFE3 in the innate immune response, independently of the mTORC1 signaling pathway. In nematodes, loss of FLCN or overexpression of AMPK confers pathogen resistance via activation of TFEB/TFE3- dependent antimicrobial genes, while ablation of total AMPK activity abolishes this phenotype. Similarly, in mammalian cells, loss of FLCN or pharmacological activation of AMPK induces TFEB/TFE3-dependent pro-inflammatory cytokine expression. Importantly, a rapid reduction in cellular ATP levels in murine macrophages is observed upon lipopolysaccharide (LPS) treatment accompanied by an acute AMPK activation and TFEB nuclear localization. These results uncover an ancient, highly conserved and pharmacologically actionable mechanism coupling energy status with innate immunity.
Project description:TFEB and TFE3 are transcriptional regulators of the innate immune response, but the mechanisms regulating their activation upon pathogen infection are poorly elucidated. Using C. elegans and mammalian models, we report that the master metabolic modulator 5'-AMP-activated protein kinase (AMPK) and its negative regulator Folliculin (FLCN) act upstream of TFEB/TFE3 in the innate immune response, independently of the mTORC1 signaling pathway. In nematodes, loss of FLCN or overexpression of AMPK confers pathogen resistance via activation of TFEB/TFE3- dependent antimicrobial genes, while ablation of total AMPK activity abolishes this phenotype. Similarly, in mammalian cells, loss of FLCN or pharmacological activation of AMPK induces TFEB/TFE3-dependent pro-inflammatory cytokine expression. Importantly, a rapid reduction in cellular ATP levels in murine macrophages is observed upon lipopolysaccharide (LPS) treatment accompanied by an acute AMPK activation and TFEB nuclear localization. These results uncover an ancient, highly conserved and pharmacologically actionable mechanism coupling energy status with innate immunity.
Project description:The mechanism by which tumor cells resist metabolic stress remains unclear, but many oncogenes are known to regulate this process. Accordingly, metabolic stress is closely associated with tumor metastasis. In this study, gene chip technology showed that RHOF, a member of the Rho GTPase family, is an oncogene that is significantly related to hepatocellular carcinoma (HCC) metastasis; however, it has rarely been reported in tumors. This study was aimed to determine the clinicopathological significance and role of RHOF in HCC progression and investigate the associated mechanisms. The results showed that compared to expression in adjacent non-cancerous tissues, RHOF was frequently upregulated in HCC tumor samples and elevated under conditions of glucose deprivation. RHOF expression was associated with TNM stage, T grade, metastasis status, recurrence, and survival in HCC. RHOF also affected cell morphology and promoted migration, invasion, and epithelial–mesenchymal transition (EMT) of HCC cell lines. Analysis of the underlying mechanism showed that RHOF promoted the Warburg effect by upregulating the expression and function of several glycolytic enzymes in HCC cells. This metabolic shift enhanced HCC cell migration and invasion. Specifically, RHOF exerted tumor-promoting effect by directly interacting with AMP-activated protein kinase (AMPK) and increasing the phosphorylation of AMPK. This subsequently affected RAB3D mRNA stability and led to elevated RAB3D expression, thereby amplifying the Warburg effect and malignant biological behaviors of HCC cells. Therefore, RHOF helps tumor cells resist metabolic stress through modulating the Warburg effect and plays a critical role in promoting HCC cell migration, invasion, and EMT, highlighting its important role in remodeling the metastatic microenvironment and regulating tumor metastasis. RHOF shows potential as a new therapeutic target and prognostic biomarker for HCC. We used microarrays to detail the global programme of gene expression associated with hepatocellular carcinoma metastasis and identified distinct classes of deregulated genes during this process.
Project description:The serine/threonine kinase LKB1 is a tumor suppressor gene which also plays key roles in metabolic function in peripheral tissues through its direct phosphorylation and activation of the AMP-activated protein kinase (AMPK). The LKB1/AMPK pathway plays key roles in the liver in suppressing transcriptional programs of gluconeogenesis and lipogenesis, and hepatic LKB1 is required for the ability of the type 2 diabetes agent metformin to lower blood glucose levels in mice. To more broadly define how the LKB1/AMPK pathway controls hepatic metabolism, transcriptional profiling was employed using mice with an inducible liver-specific deletion of Lkb1. Unexpectedly, LKB1/AMPK signaling broadly controls the expression of many phase I xenobiotic metabolism genes, including several members of the cytochrome P450 family. In particular, expression of CYP2E1, an important mediator of drug detoxification, was markedly reduced upon LKB1 loss. LKB1 liver-specific knockout mice exposed to hepatocarcinogens, exhibited marked resistance to carcinogen-induced hepatocyte apoptosis, proliferation, senescence, and liver fibrosis and tumorigenesis.
Project description:To investigate functional transcripts in metastatic HCC, we performed high-throughput RNA sequencing (RNA-seq) of tumors from 3 metastatic HCC and 3 non-metastatic HCC. And we performed RIP-seq human PLC/PRF/5 cells to investigate the HNRNPD binding transcripts. To investigate function of circLARP1B on AMPK pathway, we performed high-throughput RNA sequencing (RNA-seq) of WT (DMSO or Compound C) and circLARP1B-Def (DMSO) PLC/PRF/5 cells.
Project description:The transcription factor hepatocyte nuclear factor four alpha (Hnf4a) has various isoforms, one of which (P1-Hnf4a) is expressed in adult liver, where it functions as a tumor suppressor by providing circadian restrains at genes promoting cell proliferation and epithelial to mesenchymal transition. High fat diet feeding promotes the loss of nuclear P1-Hnf4a activity and a gain in the pro-proliferative P2-Hnf4a isoform, which does not function as a tumor suppressor, nor provide similar circadian restraint at cell cycle-promoting genes. P2-Hnf4a is found in all Hnf4a-positive hepatocellular carcinoma. Purpose: To determine whether inducible loss of hepatic Hnf4a followed by high fat feeding predisposes a liver to hepatocellular carcinoma. Methods: Hepatic Hnf4a was inducibly knocked out in mice at six weeks of age ("H4LivKO") followed by vivarium chow ("H4LivKOVC") or high fat feeding ("H4LivKOHF")at 8 weeks of age. Control, littermate wild-type mice (WT) were also treated with tamoxifen at six weeks of age, but since they lacked the Cre transgene, Hnf4a expression remained intact. Control mice were divided into the same feeding groups as H4LivKO mice ("WTVC" and "WTHF"). Livers were harvested at 38 weeks of age and liver tissue was flash frozen in liquid nitrogen. RNA was extracted from frozen liver tissue using Trizol, and purified RNA was submitted to Novogene for quality control and RNA-seq analysis using a 250-300 bp insert cDNA library and Illumina Platform sequencing.
Project description:Oxidative stress plays a critical role in liver tissue damage and in hepatocellular carcinoma (HCC) initiation and progression. However, the mechanisms that regulate autophagy and metabolic reprogramming during the generation of reactive oxygen species (ROS), and how ROS promotes tumorigenesis, still need to be fully understood. We show that protein kinase C (PKC) / loss in hepatocytes promotes autophagy and oxidative phosphorylation. This results in ROS generation, which through NRF2 drives HCC cell autonomously and non-autonomously. Although PKC / promotes tumorigenesis in oncogene-driven cancer models, emerging evidence demonstrate that it is a tumor suppressor in more complex carcinogenic processes. Consistently, PKC / levels negatively correlate with HCC histological tumor grade, establishing this kinase as a tumor suppressor in liver cancer.
Project description:Oxidative stress plays a critical role in liver tissue damage and in hepatocellular carcinoma (HCC) initiation and progression. However, the mechanisms that regulate autophagy and metabolic reprogramming during the generation of reactive oxygen species (ROS), and how ROS promotes tumorigenesis, still need to be fully understood. We show that protein kinase C (PKC) / loss in hepatocytes promotes autophagy and oxidative phosphorylation. This results in ROS generation, which through NRF2 drives HCC cell autonomously and non-autonomously. Although PKC/ promotes tumorigenesis in oncogene-driven cancer models, emerging evidence demonstrate that it is a tumor suppressor in more complex carcinogenic processes. Consistently, PKC / levels negatively correlate with HCC histological tumor grade, establishing this kinase as a tumor suppressor in liver cancer.