n-(n-(3-5-difluorophenacetyl)alanyl)phenylglycine-tert-butyl-ester and Liver-Neoplasms

Hepatitis B virus X protein (HBx) plays a crucial role in the development of hepatocellular carcinoma (HCC), however, little is known about the mechanism. Here, we investigated the relationship between HBx and Notch signaling in HepG2 cells after they were transfected with the HBx gene. It was found that HBx upregulated the expression of Notch-1, Jagged-1 and Hes-1 at the transcriptional level by binding to the Notch-1 intracellular domain, which is congruent with the observations of enhanced malignant biological activities of HBx-transfected HepG2 cells compared with normal HepG2 cells. However, while Notch signaling was blocked, the HBx-induced abnormalities were partially reversed. These findings suggest that HBx may promote the progression of HCC via the activated Notch pathway.

Topics: Apoptosis; Basic Helix-Loop-Helix Transcription Factors; Calcium-Binding Proteins; Carcinoma, Hepatocellular; Cell Cycle Checkpoints; Cell Proliferation; Dipeptides; Hep G2 Cells; Homeodomain Proteins; Humans; Intercellular Signaling Peptides and Proteins; Jagged-1 Protein; Liver Neoplasms; Membrane Proteins; Receptor, Notch1; Serrate-Jagged Proteins; Signal Transduction; Time Factors; Trans-Activators; Transcription Factor HES-1; Transfection; Viral Regulatory and Accessory Proteins

Current studies are ongoing to find new drugs for the treatment of hepatocellular carcinoma (HCC). The discovery of drugs depends on the identification of molecules that can play essential roles in the development of liver cancer, for example, Notch pathway molecules. γ-Secretase inhibitors (GSIs) can inhibit the cleavage of intramembranous substrates of all Notch receptors and subsequently suppress Notch signaling. However, whether the inhibition of the Notch pathway can suppress or promote HCC growth is still under debate. In this study, we examined the expression of Notch pathway molecules in 20 pairs of HCC tissue with their normal counterparts and a panel of eight HCC cell lines. We also determined the effects of different types of GSI treatments on the cell growth of those HCC cell lines. Our results showed that the molecules of the Notch pathway were expressed in six of the eight HCC cell lines. Those six HCC cell lines were more sensitive to GSI-I treatment than the nonexpression ones. Among the four inhibitors, GSI-X and GSI-XXI exerted no effect on HCC cells growth at all. GSI-IX inhibited the growth of four HCC cell lines at 40 μmol/l. In contrast, most of these HCC cell lines were susceptible to a low concentration of GSI-I (1.2 μmol/l) treatment. The suppressive effect of GSI-I on cell growth was because of the inhibition of C-Myc, a Notch target gene. In addition, 80% (16/20) of the specimens showed either an increased expression of at least one Notch receptor or an augmented expression of Jagged1 compared with their normal counterparts. Our study reports for the first time that different kinds of GSIs can block the growth of several HCC cell lines. Our finding suggests that GSI-I is a potential chemical reagent and warrants additional testing in liver cancer therapeutics.

Topics: Amyloid Precursor Protein Secretases; Antineoplastic Agents; Basic Helix-Loop-Helix Transcription Factors; Benzodiazepinones; Calcium-Binding Proteins; Carbamates; Carcinoma, Hepatocellular; Cell Line, Tumor; Cell Proliferation; Cell Survival; Dipeptides; Gene Expression Regulation, Neoplastic; Genes, myc; Hep G2 Cells; Homeodomain Proteins; Humans; Intercellular Signaling Peptides and Proteins; Jagged-1 Protein; Liver Neoplasms; Membrane Proteins; Oligopeptides; Receptors, Notch; Serrate-Jagged Proteins; Transcription Factor HES-1

RUNX3 takes a strong suppressive effect in many tumors including hepatocellular carcinoma (HCC). HES-1, a downstream target of Notch signaling, is shown to be decreased in human HCC cell line SMMC7721 with RUNX3 gene transfection. Since Notch signaling is oncogenic in HCC, RUNX3 might exert its inhibitory effect in HCC partly through the suppression on Notch signaling. To investigate the possible mechanism of the down-regulation of HES-1 by RUNX3, we performed Western blot and reporter assay and found that RUNX3 suppressed intracellular domain of Notch1 (ICN1)-mediated transactivation of Notch signaling while it did not alter the expression of ICN1 and recombination signal binding protein-J kappa (RBP-J) in SMMC7721 cells. Besides, confocal microscopy, co-immunoprecipitation and GST pull-down assays showed that RUNX3 could co-localize with ICN1 and RBP-J, forming a complex with these two molecules in nucleus of SMMC7721 cells by its direct interaction with ICN1. Furthermore, RUNX3 was recruited to RBP-J recognition motif of HES-1 promoter, which was identified by chromatin immunoprecipitation (ChIP) and electrophoretic mobility shift assay (EMSA). Taken together, these findings indicate that RUNX3 suppresses Notch signaling in HCC SMMC7721 cells by its interaction with ICN1 and thus recruitment to the RBP-J recognition motif of downstream genes of Notch signaling.

Topics: Basic Helix-Loop-Helix Transcription Factors; Carcinoma, Hepatocellular; Cell Line, Tumor; Cell Nucleus; Core Binding Factor Alpha 3 Subunit; Dipeptides; DNA; Gene Expression; Gene Expression Regulation, Neoplastic; Homeodomain Proteins; Humans; Immunoglobulin J Recombination Signal Sequence-Binding Protein; Liver Neoplasms; Peptide Fragments; Promoter Regions, Genetic; Protease Inhibitors; Protein Binding; Protein Interaction Domains and Motifs; Receptor, Notch1; Recombinant Fusion Proteins; Signal Transduction; Transcription Factor HES-1; Transcriptional Activation; Transfection