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Frontiers in Endocrinology 2021Cholecystokinin is a gastrointestinal peptide hormone with important roles in metabolic physiology and the maintenance of normal nutritional status, as well as potential... (Review)
Review
Cholecystokinin is a gastrointestinal peptide hormone with important roles in metabolic physiology and the maintenance of normal nutritional status, as well as potential roles in the prevention and management of obesity, currently one of the dominant causes of direct or indirect morbidity and mortality. In this review, we discuss the roles of this hormone and its receptors in maintaining nutritional homeostasis, with a particular focus on appetite control. Targeting this action led to the development of full agonists of the type 1 cholecystokinin receptor that have so far failed in clinical trials for obesity. The possible reasons for clinical failure are discussed, along with alternative pharmacologic strategies to target this receptor for prevention and management of obesity, including development of biased agonists and allosteric modulators. Cellular cholesterol is a natural modulator of the type 1 cholecystokinin receptor, with elevated levels disrupting normal stimulus-activity coupling. The molecular basis for this is discussed, along with strategies to overcome this challenge with a corrective positive allosteric modulator. There remains substantial scope for development of drugs to target the type 1 cholecystokinin receptor with these new pharmacologic strategies and such drugs may provide new approaches for treatment of obesity.
Topics: Allosteric Regulation; Animals; Cholecystokinin; Cholesterol; Humans; Obesity; Receptors, Cholecystokinin
PubMed: 34149622
DOI: 10.3389/fendo.2021.684656 -
Journal of Experimental & Clinical... Apr 2022The overall response rate to checkpoint blockade remains unsatisfactory, partially due to the immune-suppressive tumor microenvironment. A retinoic acid-related orphan...
BACKGROUND
The overall response rate to checkpoint blockade remains unsatisfactory, partially due to the immune-suppressive tumor microenvironment. A retinoic acid-related orphan receptor γt (RORγt) agonist (LYC-55716) is currently used in clinical trials combined with anti-PD-1, but how the Th17 cell transcription factor RORγt enhances antitumor immunity of PD-1 in the tumor microenvironment remains elusive.
METHODS
The expression of mRNA was analyzed using qPCR assays. Flow cytometry was used to sort and profile cells. Cell migration was analyzed using Transwell assays. Biacore was used to determine the binding affinity to the RORγt protein. The RORγt GAL4 cell-based reporter gene assay was used to measure activity in the RORγt driven luciferase reporter gene expression.
RESULTS
We designed a potent and selective small-molecule RORγt agonist (8-074) that shows robust antitumor efficacy in syngeneic tumor models and improves the efficacy of anti‑PD‑1 in a murine lung cancer model. RORγt agonist treatment increased intratumoral CD8 T cells, which were correlated with CXCL10 and monocyte-derived dendritic cells (MoDCs). In addition, the RORγt agonist promoted Type 17 T cell migration by upregulating CCL20 and CCR6 expression, and Type 17 T cell tumor infiltration. CCL20 induces MoDCs migration, and CXCL10 derived from MoDCs promotes CD8 T cell migration.
CONCLUSION
Our results revealed that the RORγt agonist improved the efficacy of anti-PD-1. The RORγt agonist increased the migration of MoDCs, which increased the local levels of CXCL10, thus promoting CD8 T cell tumor infiltration. Our findings provide the mechanistic insights implicating the RORγt agonist in immunotherapy and offer a strategy for targeting the RORγt agonist to improve PD-1 antibody efficacy in cancers.
Topics: Animals; CD8-Positive T-Lymphocytes; Chemokine CXCL10; Dendritic Cells; Humans; Lung Neoplasms; Mice; Monocytes; Nuclear Receptor Subfamily 1, Group F, Member 3; Programmed Cell Death 1 Receptor; Tumor Microenvironment
PubMed: 35459193
DOI: 10.1186/s13046-022-02289-2 -
Frontiers in Endocrinology 2023Thyroid hormone receptor β (THR-β) plays a critical role in metabolism regulation and has become an attractive target for treating lipid metabolism disorders in recent...
INTRODUCTION
Thyroid hormone receptor β (THR-β) plays a critical role in metabolism regulation and has become an attractive target for treating lipid metabolism disorders in recent years. Thus, in this study, we discovered CS271011, a novel THR-β agonist, and assessed the safety and efficiency of CS271011 compared to MGL-3196 and .
METHODS
We conducted luciferase reporter gene assays to assess the activation of THR-β and α in vitro. C57BL/6J mice were fed a high-fat diet for 12 weeks, CS271011 was administered by gavage at the dose of 1 mg/kg and 3 mg/kg, and MGL-3196 was administered at the dose of 3 mg/kg for 10 weeks. Body weight, food intake, serum and hepatic parameters, histological analysis, pharmacokinetic studies, RNA sequencing of the liver and heart, and expression of hepatic lipid-metabolic genes were determined to evaluate the safety and efficiency of CS271011.
RESULTS
Compared with MGL-3196, CS271011 showed higher THR-β activation in vitro. In the diet-induced obesity mice model, CS271011 demonstrated favourable pharmacokinetic properties in mice and was enriched in the liver. Finally, CS271011 improved dyslipidaemia and reduced liver steatosis in the diet-induced obesity murine model. Mechanistically, CS271011 and MGL-3196 showed potent regulation of lipid metabolism-related genes.
CONCLUSIONS
CS271011 is a potent and liver-targeted THR-β agonist for treating lipid metabolism disorders.
Topics: Animals; Mice; Dyslipidemias; Lipid Metabolism; Liver; Mice, Inbred C57BL; Obesity; Thyroid Hormone Receptors beta
PubMed: 36742393
DOI: 10.3389/fendo.2023.1109615 -
Scientific Reports Nov 2019Agonists of β adrenergic receptors (βAR) and glucocorticoid receptors (GR) are prescribed to treat pulmonary diseases. Since ozone effects are mediated through the...
Agonists of β adrenergic receptors (βAR) and glucocorticoid receptors (GR) are prescribed to treat pulmonary diseases. Since ozone effects are mediated through the activation of AR and GR, we hypothesized that the treatment of rats with relevant therapeutic doses of long acting βAR agonist (LABA; clenbuterol; CLEN) and/or GR agonist (dexamethasone; DEX) would exacerbate ozone-induced pulmonary and systemic changes. In the first study, male 12-week-old Wistar-Kyoto rats were injected intraperitoneally with vehicle (saline), CLEN (0.004 or 0.02 mg/kg), or DEX (0.02 or 0.1 mg/kg). Since dual therapy is commonly used, in the second study, rats received either saline or combined CLEN + DEX (each at 0.005 or 0.02 mg/kg) one day prior to and on both days of exposure (air or 0.8ppm ozone, 4 hr/day x 2-days). In air-exposed rats CLEN, DEX or CLEN + DEX did not induce lung injury or inflammation, however DEX and CLEN + DEX decreased circulating lymphocytes, spleen and thymus weights, increased free fatty acids (FFA) and produced hyperglycemia and glucose intolerance. Ozone exposure of vehicle-treated rats increased bronchoalveolar lavage fluid protein, albumin, neutrophils, IL-6 and TNF-α. Ozone decreased circulating lymphocytes, increased FFA, and induced hypeerglycemia and glucose intolerance. Drug treatment did not reverse ozone-induced ventillatory changes, however, lung effects (protein and albumin leakage, inflammation, and IL-6 increase) were exacerbated by CLEN and CLEN + DEX pre-treatment in a dose-dependent manner (CLEN > CLEN + DEX). Systemic effects induced by DEX and CLEN + DEX but not CLEN in air-exposed rats were analogous to and more pronounced than those induced by ozone. These data suggest that adverse air pollution effects might be exacerbated in people receiving LABA or LABA plus glucocorticoids.
Topics: Adrenergic beta-2 Receptor Agonists; Animals; Clenbuterol; Dexamethasone; Drug Interactions; Fatty Acids; Glucocorticoids; Glucose; Interleukin-6; Lung; Lymphocytes; Male; Ozone; Rats; Rats, Wistar; Spleen; Thymus Gland; Tumor Necrosis Factor-alpha
PubMed: 31784596
DOI: 10.1038/s41598-019-54269-w -
Biophysical Journal May 2021Agonists are evaluated by a concentration-response curve (CRC), with a midpoint (EC) that indicates potency, a high-concentration asymptote that indicates efficacy, and...
Agonists are evaluated by a concentration-response curve (CRC), with a midpoint (EC) that indicates potency, a high-concentration asymptote that indicates efficacy, and a low-concentration asymptote that indicates constitutive activity. A third agonist attribute, efficiency (η), is the fraction of binding energy that is applied to the conformational change that activates the receptor. We show that η can be calculated from EC and the asymptotes of a CRC derived from either single-channel or whole-cell responses. For 20 agonists of skeletal muscle nicotinic receptors, the distribution of η-values is bimodal with population means at 51% (including acetylcholine, nornicotine, and dimethylphenylpiperazinium) and 40% (including epibatidine, varenicline, and cytisine). The value of η is related inversely to the size of the agonist's headgroup, with high- versus low-efficiency ligands having an average volume of 70 vs. 102 Å. Most binding site mutations have only a small effect on acetylcholine efficiency, except for αY190A (35%), αW149A (60%), and those at αG153 (42%). If η is known, the EC and high-concentration asymptote can be calculated from each other. Hence, an entire CRC can be estimated from the response to a single agonist concentration, and efficacy can be estimated from EC of a CRC that has been normalized to 1. Given η, the level of constitutive activity can be estimated from a single CRC.
Topics: Binding Sites; Nicotinic Agonists; Receptors, Nicotinic
PubMed: 33675765
DOI: 10.1016/j.bpj.2021.02.034 -
Journal of Controlled Release :... May 2023Stimulator of interferon genes (STING) pathway is the key innate immune pathway involving in cancer immunity. Emerging new molecules and drug delivery systems have made...
Stimulator of interferon genes (STING) pathway is the key innate immune pathway involving in cancer immunity. Emerging new molecules and drug delivery systems have made systemic STING agonist immunotherapy possible and demonstrated efficient tumor eradication in preclinical studies. In this perspective, we will discuss the potential mechanisms of STING agonism as a multifaceted anti-cancer therapy and the pharmacological challenges associated with systemic delivery of STING agonists on the level of organs, tissues, cells, and intracellular compartments. We will present and discuss drug delivery strategies to address these challenges. New advances in the field can unlock the promise of systemic STING agonist as effective and safe cancer immunotherapy.
Topics: Humans; Immunotherapy; Membrane Proteins; Neoplasms; Signal Transduction
PubMed: 37001564
DOI: 10.1016/j.jconrel.2023.03.047 -
Biomedicines Jun 2022The present study was designed to evaluate how estradiol alone or in combination with G protein-coupled estrogen receptor (GPER) agonists and GPER and peroxisome...
Modulatory Effects of Estradiol and Its Mixtures with Ligands of GPER and PPAR on MAPK and PI3K/Akt Signaling Pathways and Tumorigenic Factors in Mouse Testis Explants and Mouse Tumor Leydig Cells.
The present study was designed to evaluate how estradiol alone or in combination with G protein-coupled estrogen receptor (GPER) agonists and GPER and peroxisome proliferator-activated receptor (PPAR) antagonists alter the expression of tumor growth factor β (TGF-β), cyclooxygenase-2 (COX-2), hypoxia inducible factor 1-alpha (HIF-1α), and vascular endothelial growth factor (VEGF) in mouse testis explants and MA-10 mouse tumor Leydig cells. In order to define the hormone-associated signaling pathway, the expression of MAPK and PI3K/Akt was also examined. Tissue explants and cells were treated with estradiol as well as GPER agonist (ICI 182,780), GPER antagonist (G-15), PPARα antagonist (GW6471), and PPARγ antagonist (T00709072) in various combinations. First, we showed that in testis explants GPER and PPARα expressions were activated by the GPER agonist and estradiol (either alone or in mixtures), whereas PPARγ expression was activated only by GPER agonist. Second, increased TGF-β expression and decreased COX-2 expression were found in all experimental groups of testicular explants and MA-10 cells, except for up-regulated COX-2 expression in estradiol-treated cells, compared to respective controls. Third, estradiol treatment led to elevated expression of HIF-1α and VEGF, while their lower levels versus control were noted in the remaining groups of explants. Finally, we demonstrated the up-regulation of MAPK and PI3Kp85/Akt expressions in estradiol-treated groups of both ex vivo and in vitro models, whereas estradiol in mixtures with compounds of agonistic or antagonistic properties either up-regulated or down-regulated signaling kinase expression levels. Our results suggest that a balanced estrogen level and its action together with proper GPER and PPAR signaling play a key role in the maintenance of testis homeostasis. Moreover, changes in TGF-β and COX-2 expressions (that disrupted estrogen pathway) as well as disturbed GPER-PPAR signaling observed after estradiol treatment may be involved in testicular tumorigenesis.
PubMed: 35740412
DOI: 10.3390/biomedicines10061390 -
Frontiers in Immunology 2022Although PD-1/L1 mAb has demonstrated clinical benefits in certain cancer types, low response rate and resistance remain the main challenges for the application of these...
INTRODUCTION
Although PD-1/L1 mAb has demonstrated clinical benefits in certain cancer types, low response rate and resistance remain the main challenges for the application of these immune checkpoint inhibitors (ICIs). 4-1BB is a co-stimulator molecule expressed in T cells, which could enhance T cell proliferation and activation. Herein, the synergetic antitumor effect and underlying mechanism of 4-1BB agonist combined with PD-1/PD-L1 blockade were determined in B-cell lymphoma (BCL).
METHODS
Subcutaneous transplantation BCL tumor models and metastasis models were established to evaluate the therapeutic effect of PD-L1 antibody and/or 4-1BB agonist in vivo. For the mechanistic study, RNA-seq was applied to analyze the tumor microenvironment and immune-related signal pathway after combination treatment. The level of IFN-γ, perforin, and granzyme B were determined by ELISA and Real-time PCR assays, while tumor-infiltrating T cells were measured by flow cytometry and immunohistochemical analysis. CD4/CD8 specific antibodies were employed to deplete the related T cells to investigate the role CD4+ and CD8+ T cells played in combination treatment.
RESULTS
Our results showed that combining anti-PD-L1 ICI and 4-1BB agonists elicited regression of BCL and significantly extended the survival of mice compared to either monotherapy. Co-targeting PD-L1 and 4-1BB preferentially promoted intratumoral cytotoxic lymphocyte infiltration and remodeled their function. RNA-sequence analysis uncovered a series of up-regulated genes related to the activation and proliferation of cytotoxic T lymphocytes, further characterized by increased cytokines including IFN-γ, granzyme B, and perforin. Furthermore, depleting CD8+ T cells not CD4+ T cells totally abrogated the antitumor efficacy, indicating the crucial function of the CD8+ T cell subset in the combination therapy.
DISCUSSION
In summary, our findings demonstrated that 4-1BB agonistic antibody intensified the antitumor immunity of anti-PD-1/PD-L1 ICI via promoting CD8+ T cell infiltration and activation, providing a novel therapeutic strategy to BCL.
Topics: Animals; Mice; Antineoplastic Agents; Granzymes; Lymphoma, B-Cell; Neoplasms; Perforin; Tumor Microenvironment
PubMed: 36544785
DOI: 10.3389/fimmu.2022.1004475 -
Nature Communications Jan 2022Much effort has been invested in the investigation of the structural basis of G protein-coupled receptors (GPCRs) activation. Inverse agonists, which can inhibit GPCRs...
Much effort has been invested in the investigation of the structural basis of G protein-coupled receptors (GPCRs) activation. Inverse agonists, which can inhibit GPCRs with constitutive activity, are considered useful therapeutic agents, but the molecular mechanism of such ligands remains insufficiently understood. Here, we report a crystal structure of the ghrelin receptor bound to the inverse agonist PF-05190457 and a cryo-electron microscopy structure of the active ghrelin receptor-Go complex bound to the endogenous agonist ghrelin. Our structures reveal a distinct binding mode of the inverse agonist PF-05190457 in the ghrelin receptor, different from the binding mode of agonists and neutral antagonists. Combining the structural comparisons and cellular function assays, we find that a polar network and a notable hydrophobic cluster are required for receptor activation and constitutive activity. Together, our study provides insights into the detailed mechanism of ghrelin receptor binding to agonists and inverse agonists, and paves the way to design specific ligands targeting ghrelin receptors.
Topics: Cryoelectron Microscopy; Crystallography, X-Ray; Ghrelin; Humans; Ligands; Mutation; Protein Binding; Receptors, Ghrelin
PubMed: 35027551
DOI: 10.1038/s41467-022-27975-9