gw-3965 and Liver-Neoplasms

Sorafenib resistance is a major obstacle to the treatment of advanced hepatocellular carcinoma (HCC). MicroRNAs (miRNAs) are multifunctional regulators of gene expression with profound impact for human disease. Therefore, better understanding of the biological mechanisms of abnormally expressed miRNAs is critical to discovering novel, promising therapeutic targets for HCC treatment. This study aimed to investigate the role of miR-378a-3p in the sorafenib resistance of HCC and elucidate the underlying molecular mechanisms.

Topics: Animals; Benzoates; Benzylamines; Carcinoma, Hepatocellular; Cell Line, Tumor; Cell Proliferation; Cell Survival; Down-Regulation; Drug Resistance, Neoplasm; Drug Synergism; Gene Expression Regulation, Neoplastic; Humans; Karyopherins; Liver Neoplasms; Liver X Receptors; Male; Mice; MicroRNAs; Middle Aged; Neoplasm Transplantation; Receptor, IGF Type 1; Sorafenib; Survival Analysis

Liver X receptors (LXRs), including LXRα and LXRβ isoforms, have important roles in the metabolic regulation of glucose, cholesterol and lipid. Moreover, activation of LXRs also represses the expression of cyclin D1 and cyclin B1, and thus suppresses the proliferation of multiple cancer cells, but the relevant mechanism is not well known. Forkhead box M1 (FOXM1) is a proliferation-specific member of forkhead box family, which is highly expressed in proliferating normal cells and numerous cancer cells. FOXM1 directly activates transcription of cyclin D1 and cyclin B1, resulting in the enhancement of cell cycle progression and cell proliferation. However, it is unclear whether LXRs are involved in the regulation of FOXM1. In this study, we demonstrated that specific LXRs agonists downregulated expression of FOXM1, cyclin D1 and cyclin B1 in hepatocellular carcinoma (HCC) cells, which led to cell cycle and cell proliferation arrest. Knockdown of FOXM1 significantly alleviated LXRs activation-mediated cell cycle arrest and cell growth suppression. Reporter assays showed that the activation of LXRs significantly reduced the transcriptional activity of FOXM1 promoter. Electrophoretic mobility shift assay and chromatin immunoprecipitation assays demonstrated that LXRα but not LXRβ could bind to an inverted repeat IR2 (-52CCGTCAcgTGACCT-39) in the promoter region of FOXM1 gene. Moreover, the xenograft tumor growth and the corresponding FOXM1 expression in nude mice were dramatically repressed by LXRs agonists. Taken together, we conclude that LXRα but not LXRβ functions as a transcriptional repressor for FOXM1 expression. The pathway 'LXRα-FOXM1-cyclin D1/cyclin B1' is a novel mechanism by which LXRs suppress the proliferation of HCC cells, suggesting that the pathway may be a novel target for HCC treatment.

Topics: Animals; Base Sequence; Benzoates; Benzylamines; Carcinoma, Hepatocellular; Cell Line, Tumor; Cell Proliferation; Cyclin B1; Cyclin D1; Disease Models, Animal; Down-Regulation; Forkhead Box Protein M1; Forkhead Transcription Factors; G1 Phase Cell Cycle Checkpoints; Gene Expression Regulation, Neoplastic; Gene Knockdown Techniques; Hepatocytes; Heterografts; Humans; Liver Neoplasms; Liver X Receptors; Mice; Molecular Sequence Data; Orphan Nuclear Receptors; Promoter Regions, Genetic; Protein Binding; Transcription, Genetic

C-reactive protein (CRP), the prototypical human acute phase protein, is an independent risk predictor of future cardiovascular events, both in healthy individuals and in patients with known cardiovascular disease. In addition, previous studies indicate that CRP might have direct proatherogenic properties. Ligand activation of the liver X receptor (LXR), a member of the nuclear hormone receptor superfamily, inhibits inflammatory gene expression in macrophages and attenuates the development of atherosclerosis in various animal models. We demonstrate herein that 2 synthetic LXR ligands, T0901317 and GW3965, inhibit interleukin-1beta/interleukin-6-induced CRP mRNA and protein expression in human hepatocytes. Knockdown of LXRalpha/beta by short interfering RNAs completely abolished the inhibitory effect of the LXR agonist T0901317 on cytokine-induced CRP gene transcription. Transient transfection experiments with 5'-deletion CRP promoter constructs identified a region from -125 to -256 relative to the initiation site that mediated the inhibitory effect of LXR ligands on CRP gene transcription. Depletion of the nuclear receptor corepressor by specific short interfering RNA increased cytokine-inducible CRP mRNA expression and promoter activity and reversed LXR ligand-mediated repression of CRP gene transcription. Chromatin immunoprecipitation assays indicated that nuclear receptor corepressor is present on the endogenous CRP promoter under basal conditions. Cytokine-induced clearance of nuclear receptor corepressor complexes was inhibited by LXR ligand treatment, maintaining the CRP gene in a repressed state. Finally, treatment of C57Bl6/J mice with LXR ligands attenuated lipopolysaccharide-induced mouse CRP and serum amyloid P component gene expression in the liver, whereas no effect was observed in LXRalphabeta knockout mice. Our observations identify a novel mechanism of inflammatory gene regulation by LXR ligands. Thus, inhibition of CRP expression by LXR agonists may provide a promising approach to impact initiation and progression of atherosclerosis.

Topics: Acute-Phase Reaction; Animals; Benzoates; Benzylamines; C-Reactive Protein; Carcinoma, Hepatocellular; Cell Line, Tumor; DNA-Binding Proteins; Gene Expression; Hepatocytes; Humans; Hydrocarbons, Fluorinated; Interleukin-1beta; Interleukin-6; Ligands; Liver Neoplasms; Liver X Receptors; Male; Mice; Mice, Inbred C57BL; Nuclear Proteins; Nuclear Receptor Co-Repressor 1; Orphan Nuclear Receptors; Promoter Regions, Genetic; Receptors, Cytoplasmic and Nuclear; Repressor Proteins; RNA, Small Interfering; Signal Transduction; Sulfonamides; Transcription, Genetic