Differential mRNA expression profile regulated by HNF4α in Hep3B cells
ABSTRACT: A previous study from this laboratory demonstrated that up-regulating HNF4a could reverse the malignant phenotypes of HCC by inducing redifferentiation of HCC cells to hepatocytes. To study the mechanisms of the hepatic differentiation effect by HNF4α, we used the cDNA microarray to detect differential gene expression profiles of Hep3B infected with AdHNF4α and AdGFP. Expression profile analysis revealed that HNF4α positively regulated 1218 mRNAs and negatively regulated 1411 mRNAs for more than 2 times. The pathway analysis for the differential genes showed that the genes were involved in Complement and coagulation cascades, metabolism, Type II diabetes mellitus, Pathways in cancer etc. Overall design: Hepatoma cell lines Hep3B cells were seeded onto culture dishes and infected with AdHNF4α and AdGFP (as a control) at MOI 100. After Hep3B was infected by AdHNF4α or AdGFP for 72 hours, the cells were collected for cDNA Microarray analysis.
INSTRUMENT(S): [HG-U133_Plus_2] Affymetrix Human Genome U133 Plus 2.0 Array
Project description:Hepatocyte nuclear factor 4α (HNF4α) controls the expression of liver-specific protein-coding genes. However, some microRNAs are also modulated by HNF4α, and it is not known whether they are direct targets of HNF4α and whether they influence hepatic function. In this study, we found that HNF4α regulates microRNAs, indicated by marked down-regulation of miR-194 and miR-192 (miR-194/192) in liver-specific Hnf4a-null (Hnf4aΔH) mice. Transactivation of the shared miR-194/192 promoter was dependent on HNF4α expression, indicating that miR-194/192 is a target gene of HNF4α. Screening of potential mRNAs targeted by miR-194/192 revealed that expression of genes involved in glucose metabolism (glycogenin 1 (Gyg1)), cell adhesion and migration (activated leukocyte cell adhesion molecule (Alcam)), tumorigenesis and tumor progression (Rap2b and epiregulin (Ereg)), protein SUMOylation (Sumo2), epigenetic regulation (Setd5 and Cullin 4B (Cln4b)), and the epithelial-mesenchymal transition (moesin (Msn)) was up-regulated in Hnf4aΔH mice. Moreover, we also found that miR-194/192 binds the 3'-UTR of these mRNAs. siRNA knockdown of HNF4α suppressed miR-194/192 expression in human hepatocellular carcinoma (HCC) cells and resulted in up-regulation of their mRNA targets. Inhibition and overexpression experiments with miR-194/192 revealed that Gyg1, Setd5, Sumo2, Cln4b, and Rap2b are miR-194 targets, whereas Ereg, Alcam, and Msn are miR-192 targets. These findings reveal a novel HNF4α network controlled by miR-194/192 that may play a critical role in maintaining the hepatocyte-differentiated state by inhibiting expression of genes involved in dedifferentiation and tumorigenesis. These insights may contribute to the development of diagnostic markers for early HCC detection, and targeting of the miR-194/192 pathway could be useful for managing HCC.
Project description:Hepatocyte nuclear factor 4α (HNF4α) is a critical factor for hepatocyte differentiation. HNF4α expression is decreased in hepatocellular carcinoma (HCC), which suggests a role in repression of hepatocyte dedifferentiation. In the present study, hepatic expression of HNF4γ was increased in liver-specific Hnf4a-null mice. The HNF4γ whose expression was increased contained two variants, a known short variant, designated HNF4γ1, and a novel long variant, designated HNF4γ2. HNF4G2 mRNA was highly expressed in small intestine, and the transactivation potential of HNF4γ2 was the strongest among these variants, but the potential of HNF4γ1 was the lowest. Cotransfection experiments revealed that HNF4γ1 repressed HNF4α- and HNF4γ2-dependent transactivation, while HNF4γ2 promoted HNF4α-dependent transactivation. HNF4γ1 and HNF4γ2 were able to bind to the HNF4α binding sites with an affinity similar to that of HNF4α. Furthermore, HNF4γ2, but not HNF4γ1, robustly induced the expression of typical HNF4α target genes to a greater degree than HNF4α. Additionally, HNF4γ2 suppressed proliferation of hepatoma cells as well as HNF4α and HNF4γ1 did, and HNF4γ2 induced critical hepatic functions, such as glucose and urea production, and cytochrome P450 1A2 activity more strongly than HNF4α and HNF4γ1 did. These results indicate that HNF4γ2 has potential for redifferentiation of HCC and thus may be explored as a target for HCC therapy.
Project description:Elevated levels of circulating asymmetric and symmetric dimethylarginines (ADMA and SDMA) predict and potentially contribute to end organ damage in cardiovascular diseases. Alanine-glyoxylate aminotransferase 2 (AGXT2) regulates systemic levels of ADMA and SDMA, and also of beta-aminoisobutyric acid (BAIB)-a modulator of lipid metabolism. We identified a putative binding site for hepatic nuclear factor 4 α (HNF4α) in AGXT2 promoter sequence. In a luciferase reporter assay we found a 75% decrease in activity of Agxt2 core promoter after disruption of the HNF4α binding site. Direct binding of HNF4α to Agxt2 promoter was confirmed by chromatin immunoprecipitation assay. siRNA-mediated knockdown of Hnf4a led to an almost 50% reduction in Agxt2 mRNA levels in Hepa 1-6 cells. Liver-specific Hnf4a knockout mice exhibited a 90% decrease in liver Agxt2 expression and activity, and elevated plasma levels of ADMA, SDMA and BAIB, compared to wild-type littermates. Thus we identified HNF4α as a major regulator of Agxt2 expression. Considering a strong association between human HNF4A polymorphisms and increased risk of type 2 diabetes our current findings suggest that downregulation of AGXT2 and subsequent impairment in metabolism of dimethylarginines and BAIB caused by HNF4α deficiency might contribute to development of cardiovascular complications in diabetic patients.
Project description:Mutations in the HNF4A gene cause MODY1 and are associated with an increased risk of Type 2 diabetes mellitus. On the other hand, incretins are hormones that potentiate reductions in blood glucose levels. Given the established role of incretin-based therapy to treat diabetes and metabolic disorders, we investigated a possible regulatory link between intestinal epithelial HNF4α and glucose-dependent insulinotropic polypeptide (GIP), an incretin that is specifically produced by gut enteroendocrine cells. Conditional deletion of HNF4α in the whole intestinal epithelium was achieved by crossing Villin-Cre and Hnf4αloxP/loxP C57BL/6 mouse models. GIP expression was measured by qPCR, immunofluorescence and ELISA. Gene transcription was assessed by luciferase and electrophoretic mobility shift assays. Metabolic parameters were analyzed by indirect calorimetry and dual-energy X-ray absorptiometry. HNF4α specific deletion in the intestine led to a reduction in GIP. HNF4α was able to positively control Gip transcriptional activity in collaboration with GATA-4 transcription factor. Glucose homeostasis and glucose-stimulated insulin secretion remained unchanged in HNF4α deficient mice. Changes in GIP production in these mice did not impact nutrition or energy metabolism under normal physiology but led to a reduction of bone area and mineral content, a well described physiological consequence of GIP deficiency. Our findings point to a novel regulatory role between intestinal HNF4α and GIP with possible functional impact on bone density.
Project description:Background: Liver cancer stem cells (LCSCs) are responsible for the initiation, progression and chemoresistance of liver cancer. However, no agent targeting LCSC is available in the clinic to date. Here, we investigated the effects of targeting protein arginine methyltransferase 5 (PRMT5), an epigenetic regulator, on LCSCs and HCC using a novel PRMT5 inhibitor DW14800. Methods: Tumor spheroid formation culture was used to enrich LCSCs and assess their self-renewal capability. Human alpha-1-antitrypsin (A1AT) ELISA, acetylated low-density lipoprotein (ac-LDL) uptake, periodic acid-Schiff (PAS) reactions and senescence associated β-galactosidase (SA-β-gal) activity assays were performed to examine the differentiation status of HCC cells. The effects of DW14800 on HCC malignancy were assessed in HCC cell lines and on an HCC xenograft model in mice. Chromatin immunoprecipitation was applied to clarify the transcriptional regulation of HNF4α by PRMT5-mediated Histone H4 arginine-3 symmetrical dimethylation (H4R3me2s). Results: Quantitative real-time PCR revealed that the expression of PRMT5 was upregulated in LCSCs. DW14800 specifically decreased the symmetrical dimethylation of arginine residues in HCC cells. Treatment of DW14800 suppressed the self-renewal capacity of LCSCs while re-establishing hepatocyte-specific characteristics in HCC cells. DW14800 displayed antitumor effects in HCC cells in vitro and in xenograft HCC in vivo. Importantly, ChIP assay showed that PRMT5 and H4R3me2s bound to the promoter region of HNF4α gene, and DW14800 increased the expression of HNF4α via reducing the H4R3me2s levels and enhancing the transcription of HNF4α. Conclusions: Our data revealed the significance of targeting PRMT5 activity in LCSC elimination and HCC differentiation, and proposed that DW14800 may represent a promising therapeutic agent for HCC in the clinic.
Project description:MicroRNA-122 (miR-122) is implicated as a regulator of physiological and pathophysiological processes in the liver. Overexpression of Gα12 is associated with overall survival in patients with hepatocellular carcinoma (HCC). Array-based miRNA profiling was performed on Huh7 stably transfected with activated Gα12 to find miRNAs regulated by the Gα12 pathway; among them, miR-122 was most greatly repressed. miR-122 directly inhibits c-Met expression, playing a role in HCC progression. Gα12 destabilized HNF4α by accelerating ubiquitination, impeding constitutive expression of miR-122. miR-122 mimic transfection diminished the ability of Gα12 to increase c-Met and to activate ERK, STAT3, and Akt/mTOR, suppressing cell proliferation with augmented apoptosis. Consistently, miR-122 transfection prohibited tumor cell colony formation and endothelial tube formation. In a xenograft model, Gα12 knockdown attenuated c-Met expression by restoring HNF4α levels, and elicited tumor cell apoptosis but diminished Ki67 intensities. In human HCC samples, Gα12 levels correlated to c-Met and were inversely associated with miR-122. Both miR-122 and c-Met expression significantly changed in tumor node metastasis (TNM) stage II/III tumors. Moreover, changes in Gα12 and miR-122 levels discriminated recurrence-free and overall survival rates of HCC patients. Collectively, Gα12 overexpression in HCC inhibits MIR122 transactivation by inactivating HNF4α, which causes c-Met induction, contributing to cancer aggressiveness.
Project description:Although they are expandable in vitro, hepatic progenitors are immature cells and share many immunomarkers with hepatocellular carcinoma, raising potential concerns regarding maltransformation after transplantation. This study investigated the effects of hepatic nuclear factor (HNF) 4α on the proliferation, migration, and maltransformation of hepatic progenitors and determined the feasibility of using these manipulated cells for transplantation.The effects of HNF4α on rat hepatic progenitors (i.e. hepatic oval cells) were analyzed by HNF4α overexpression and HNF4α shRNA. Nonobese diabetic/severe combined immunodeficiency (NOD/SCID) mice injured by carbon chloride (CCl4) were then transplanted with control, HNF4α-overexpressing or HNF4α-suppressing hepatic oval cells. Finally, the engraftment of these cells in the recipient liver was analyzed.Rat hepatic progenitors (i.e. hepatic oval cells) expressed HNF4α, although less than that in hepatocytes. When HNF4α was overexpressed in these cells, the proliferation and migration of hepatic oval cells were reduced; but when HNF4α was suppressed by shRNA, the proliferation and migration, and even anchorage-independent growth, of these cells were accelerated. RNA microarray and gene functional analysis revealed that suppressing HNF4α not only impaired many biosynthesis and metabolism pathways of hepatocytes but also increased pathways for cancer. When transplanted into CCl4-injured NOD/SCID mice, few HNF4α-suppressing hepatic oval cells localized into the liver, while control cells and HNF4α-overexpressing cells engrafted into the liver and differentiated into albumin-positive hepatocytes. Interestingly, the hepatocytes derived from HNF4α-overexpressing cells were less migrative and expressed less c-Myc than the cells derived from control cells.HNF4α constrains proliferation, migration, and maltransformation of hepatic progenitors, and HNF4α-overexpressing hepatic progenitors serve as an optimal candidate for cell transplantation.
Project description:Src tyrosine kinase has long been implicated in colon cancer but much remains to be learned about its substrates. The nuclear receptor hepatocyte nuclear factor 4α (HNF4α) has just recently been implicated in colon cancer but its role is poorly defined. Here we show that c-Src phosphorylates human HNF4α on three tyrosines in an interdependent and isoform-specific fashion. The initial phosphorylation site is a Tyr residue (Y14) present in the N-terminal A/B domain of P1- but not P2-driven HNF4α. Phospho-Y14 interacts with the Src SH2 domain, leading to the phosphorylation of two additional tyrosines in the ligand binding domain (LBD) in P1-HNF4α. Phosphomimetic mutants in the LBD decrease P1-HNF4α protein stability, nuclear localization and transactivation function. Immunohistochemical analysis of approximately 450 human colon cancer specimens (Stage III) reveals that P1-HNF4α is either lost or localized in the cytoplasm in approximately 80% of tumors, and that staining for active Src correlates with those events in a subset of samples. Finally, three SNPs in the human HNF4α protein, two of which are in the HNF4α F domain that interacts with the Src SH3 domain, increase phosphorylation by Src and decrease HNF4α protein stability and function, suggesting that individuals with those variants may be more susceptible to Src-mediated effects. This newly identified interaction between Src kinase and HNF4α has important implications for colon and other cancers.
Project description:Fibroblast growth factor receptors (FGFRs) are frequently altered in a variety of human cancer cells and are overexpressed in hepatocellular carcinoma (HCC). Several literatures have proven that they are efficacious for HCC therapy, however, the underlying mechanism remains unclear. Here, we found FGFR4 was overexpressed in HCC cell lines HepG2 and Hep3B and we used PD173074, an FGFR4 inhibitor, to explore the role of FGFR4 and its underlying mechanism in these cell lines. The results showed that PD173074 significantly arrested HepG2 and Hep3B cells in G1 phase and inhibited cell proliferation. Furthermore, Western blot analysis revealed that PD173074 decreased the levels of P-FRS2?, P-ERK, CDK2, cyclin E and NF-?B (p65) in the nucleus while it increased the levels of ubiquitin and CUL3, an E3 ubiquitin ligase which involves in cyclin E degradation. Meanwhile, the data from RT-qPCR showed that PD173074 also decreased miR-141 level. In conclusion, these results suggest that FGFR4 is involved in HCC by ERK/CUL3/cyclin E signaling pathway, and the finding may provide a potential theoretical basis for treatment by targeting FGFR4 in HCC.
Project description:Targeted therapy may provide survival benefit for advanced hepatocellular carcinoma (HCC) and Aurora A kinase (AURKA) represents a feasible target in cancer treatment. The purpose of this study is to investigate the anticancer activity of alisertib (ALS) on Hep3B cells based on a proteomic study conducted with the stable-isotope labeling by amino acids in cell culture (SILAC). The proteomic response to ALS was obtained with SILAC-based proteomic study. Cell cycle distribution and apoptosis were assessed using flow cytometry and autophagy was determined using flow cytometry and confocal microscopy. ALS inhibited the proliferation of Hep3B cells, with IC50 values for 24- and 48-h exposure of 46.8 and 28.0 ?M, respectively. Our SILAC study demonstrated that there were at least 565 proteins responding to ALS treatment, with 256 upregulated, 275 downregulated and 35 stable. Ninety-four signaling pathways, majority of which involved cell proliferation and survival, programmed cell death, and nutrition and energy metabolism, were regulated by ALS. ALS significantly inhibited the phosphorylation of AURKA at Thr288 in a concentration-dependent manner. Subsequent study showed that ALS remarkably arrested Hep3B cells in G2/M phase via regulating the expression of key cell cycle regulators, and induced a marked autophagy via the PI3K/Akt/mTOR axis. Inhibition of autophagy enhanced the anticancer activity of ALS in Hep3B cells. Overall, ALS leads to comprehensive proteomic response, inhibits cellular proliferation, and induces cell cycle arrest and autophagy in Hep3B cells. Further studies are warranted to explore the role of ALS in the treatment of HCC.