ABSTRACT
Glucagon-like peptide-1 (GLP-1) plays a role in the regulation of adipogenesis; however, the precise underlying molecular mechanism has not been fully defined. Wnt was recently identified as an important regulator of adipogenesis. This study aimed to investigate the involvement of the Wnt signaling pathway in the effects of GLP-1 on adipocyte differentiation. 3T3-L1 cells were induced to differentiate. The changes in the expression levels of adipogenic transcription factors and Wnts and the phosphorylation level and subcellular localization of ß-catenin were quantified after GLP-1 treatment. GLP-1 stimulated adipocyte differentiation and lipid accumulation, which were accompanied by the expression of adipocyte marker genes. The expression of Wnt4 was upregulated in the process of adipocyte differentiation, which was further enhanced by treatment with GLP-1. ß-catenin, an important mediator of the Wnt pathway, was immediately dephosphorylated and translocated from cytoplasm to nucleus when differentiation was induced. In the presence of GLP-1, however, ß-catenin was redirected to the cell plasma membrane leading to its decreased accumulation in the nucleus. Knockdown of Wnt4 blocked the effect of GLP-1 on the cellular localization of ß-catenin and expression level of adipogenic transcription factors. Our findings showed that GLP-1 promoted adipogenesis through the modulation of the Wnt4/ß-catenin signaling pathway, suggesting that the GLP-1-Wntß-catenin system might be a new target for the treatment of metabolic disease.
Subject(s)
Adipocytes/cytology , Adipocytes/drug effects , Cell Differentiation/drug effects , Glucagon-Like Peptide 1/pharmacology , Wnt4 Protein/metabolism , beta Catenin/metabolism , 3T3-L1 Cells , Adipocytes/metabolism , Animals , Cell Membrane/drug effects , Cell Membrane/metabolism , Cell Proliferation/drug effects , Gene Expression Regulation/drug effects , Mice , Protein Transport/drug effects , Wnt Signaling Pathway/drug effectsABSTRACT
Rhythmic incremental growth lines and the presence of melatonin receptors were discovered in tooth enamel, suggesting possible role of circadian rhythm. We therefore hypothesized that circadian rhythm may regulate enamel formation through melatonin receptors. To test this hypothesis, we examined expression of melatonin receptors (MTs) and amelogenin (AMELX), a maker of enamel formation, during tooth germ development in mouse. Using qRT-PCR and immunocytochemistry, we found that mRNA and protein levels of both MTs and AMELX in normal mandibular first molar tooth germs increased gradually after birth, peaked at 3 or 4 day postnatal, and then decreased. Expression of MTs and AMELX by immunocytochemistry was significantly delayed in neonatal mice raised in all-dark or all-light environment as well as the enamel development. Furthermore, development of tooth enamel was also delayed showing significant immature histology in those animals, especially for newborn mice raised in all daylight condition. Interestingly, disruption in circadian rhythm in pregnant mice also resulted in delayed enamel development in their babies. Treatment with melatonin receptor antagonist 4P-PDOT in pregnant mice caused underexpression of MTs and AMELX associated with long-lasting deficiency in baby enamel tissue. Electromicroscopic evidence demonstrated increased necrosis and poor enamel mineralization in ameloblasts. The above results suggest that circadian rhythm is important for normal enamel development at both pre- and postnatal stages. Melatonin receptors were partly responsible for the regulation.
Subject(s)
Circadian Rhythm/physiology , Dental Enamel/metabolism , Molar/metabolism , Ameloblasts/cytology , Ameloblasts/metabolism , Amelogenin/genetics , Amelogenin/metabolism , Animals , Animals, Newborn , Circadian Rhythm/radiation effects , Dental Enamel/drug effects , Dental Enamel/growth & development , Dental Enamel Proteins/genetics , Female , Immunohistochemistry , Light , Mice , Mice, Inbred BALB C , Microscopy, Electron , Molar/pathology , Pregnancy , Real-Time Polymerase Chain Reaction , Receptors, Melatonin/antagonists & inhibitors , Receptors, Melatonin/genetics , Receptors, Melatonin/metabolism , Tetrahydronaphthalenes/pharmacology , Tooth Germ/metabolism , Tooth Germ/pathologyABSTRACT
The Cancer Genome Atlas (TCGA) project recently identified the importance of mutations in chromatin remodeling genes in human carcinomas. These findings imply that epigenetic modulators might have a therapeutic role in urothelial cancers. To exploit histone deacetylases (HDACs) as targets for cancer therapy, we investigated the HDAC inhibitors (HDACIs) romidepsin, trichostatin A, and vorinostat as potential chemotherapeutic agents for bladder cancer. We demonstrate that the three HDACIs suppressed cell growth and induced cell death in the bladder cancer cell line 5637. To identify potential mechanisms associated with the anti-proliferative and cytotoxic effects of the HDACIs, we used quantitative proteomics to determine the proteins potentially involved in these processes. Our proteome studies identified a total of 6003 unique proteins. Of these, 2472 proteins were upregulated and 2049 proteins were downregulated in response to HDACI exposure compared to the untreated controls (P<0.05). Bioinformatic analysis further revealed that those differentially expressed proteins were involved in multiple biological functions and enzyme-regulated pathways, including cell cycle progression, apoptosis, autophagy, free radical generation and DNA damage repair. HDACIs also altered the acetylation status of histones and non-histone proteins, as well as the levels of chromatin modification proteins, suggesting that HDACIs exert multiple cytotoxic actions in bladder cancer cells by inhibiting HDAC activity or altering the structure of chromatin. We conclude that HDACIs are effective in the inhibition of cell proliferation and the induction of apoptosis in the 5637 bladder cancer cells through multiple cell death-associated pathways. These observations support the notion that HDACIs provide new therapeutic options for bladder cancer treatment and thus warrant further preclinical exploration.
Subject(s)
Antineoplastic Agents/pharmacology , Histone Deacetylase Inhibitors/pharmacology , Proteome/drug effects , Proteomics/methods , Urinary Bladder Neoplasms/metabolism , Cell Death , Cell Line, Tumor , Cell Proliferation/drug effects , Cell Survival/drug effects , Depsipeptides/pharmacology , Epigenesis, Genetic , Gene Expression Regulation, Neoplastic/drug effects , Humans , Hydroxamic Acids/pharmacology , Signal Transduction/drug effects , Urinary Bladder Neoplasms/drug therapy , VorinostatABSTRACT
The treatment of nonmuscle-invasive urothelial carcinoma with bacillus Calmette-Guérin (BCG) represents the importance of immunotherapy in the treatment of cancer. Despite its clinical efficacy, up to 30% of patients will ultimately experience progression to muscle-invasive disease. This, along with an improved understanding of the biologic pathways involved, has led to efforts to improve, enhance, or alter the immune response in the treatment of urothelial carcinoma. A number of novel therapeutic approaches currently are being pursued, including recombinant BCG to induce T helper type 1 (Th1) immune responses, nonlive Mycobacterium agents, targeted agents toward cancer-associated antigens, immune-modulating vaccines, and adoptive T-cell therapies. Here, we review the current and future immunotherapy treatment options for patients with urothelial cancer.
