Showing papers by "Graeme Milligan published in 2023"
TL;DR: In this article , new information on the biology of the G-protein-coupled receptor 35 (GPR35) is considered, whilst insight into how GPR35 is currently being assessed for therapeutic utility in areas ranging from inflammatory bowel diseases to nonalcoholic steatohepatitis and various cancers.
3 citations
TL;DR: In this article , the authors showed that GPR35 is activated by lithocholic acid, which is a G protein-coupled receptor primarily expressed in digestive system epithelial tissues and cells of myeloid lineage.
Abstract:
Cancers of the digestive tract are a major area of unmet clinical need with incidence rates of some cancers increasing and early onset forms becoming more prevalent. Environmental factors, such as poor diet and microbiota, as well as inflammatory conditions, are strongly associated with occurrence of digestive system cancers. Obesogenic diet combined with microbiotic metabolism can lead to high levels of secondary bile acids in the human gut. Secondary bile acids deoxy- and litho-cholic acid have been shown to have oncogenic potential and their levels are increased in the intestines of cancer patients relative to healthy controls. GPR35 is an orphan class A G protein-coupled receptor primarily expressed in digestive system epithelial tissues and cells of myeloid lineage. GPR35 polymorphisms are strongly associated with inflammatory bowel diseases. In particular, rs37947171, a missense variant that codes for a threonine to methionine substitution at position 108 (T108M) and has been shown to have hypermorphic function, is strongly associated with Crohn’s disease and ulcerative colitis. GPR35 is also overexpressed in adenocarcinomas of the digestive tract, including those of esophageal, hepatic/bile ductal, pancreatic, gastric and colorectal origin, and high expression has been shown to confer poor prognosis in various digestive system cancers. Consistent with a proposed role in digestive tract cancers we now show that GPR35 is activated by lithocholic acid. Furthermore, we demonstrate through CRISPR-gene editing of cancer cells and RNAseq analysis that GPR35 can regulate transcriptional and cytoskeletal modules associated with hallmarks of cancer, including chemokine and growth factor expression and F-actin formation. GPR35 activates a transcriptional program that is enriched for genes containing pro-oncogenic serum response factor response element in their upstream promoters. High throughput screening and medicinal chemistry optimization has led to the discovery of potent antagonists of GPR35 signalling. Pharmacological characterisation of lead series has shown that they are able to prevent Gα and β-arrestin protein binding, while also inhibiting phospho-ERK, calcium flux, receptor internalisation and serum response factor-induced gene transcription. Furthermore, the series are competitive with predicted orthosteric agonist, can block activation of receptor signalling by lithocholic acid and act as inverse agonists of constitutive receptor tone. Profiling these inhibitors in cancer models is currently ongoing. This work provides the basis for the pre-clinical development of GPR35 inverse agonists as anti-cancer drugs.
Citation Format: James Westcott, Christopher A. Luckhurst, Grahame McKenzie, Danish Memon, Li-Chiung Lin, Sinead Knight, Elizabeth J. Blaikley, Martin Pearce, Hannah R. Warren, Eleanor Parker, Graeme Milligan, Stuart W. Hughes, Tom McCarthy. Validation of GPR35 as a novel cancer target in digestive tract cancers and discovery of potent, selective GPR35 inverse agonists [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 454.
TL;DR: In this article , the results from bioisosteric replacement of the carboxylic acid group of the established FFA2 antagonist CATPB and SAR investigations around these compounds, leading to the discovery of the first high-potency FFA 2 antagonists, with the preferred compound TUG-2304 (16l) featuring IC50 values of 3-4 nM in both cAMP and GTPγS assays, favorable physicochemical and pharmacokinetic properties, and the ability to completely inhibit propionate-induced neutrophil migration and respiratory burst.
Abstract: The free fatty acid receptor 2 (FFA2), also known as GPR43, mediates effects of short-chain fatty acids and has attracted interest as a potential target for treatment of various metabolic and inflammatory diseases. Herein, we report the results from bioisosteric replacement of the carboxylic acid group of the established FFA2 antagonist CATPB and SAR investigations around these compounds, leading to the discovery of the first high-potency FFA2 antagonists, with the preferred compound TUG-2304 (16l) featuring IC50 values of 3-4 nM in both cAMP and GTPγS assays, favorable physicochemical and pharmacokinetic properties, and the ability to completely inhibit propionate-induced neutrophil migration and respiratory burst.
TL;DR: In this article , the authors consider what is known about the regulation of GPR84 signalling with a focus on how G protein receptor kinase -mediated phosphorylation regulates arrestin protein recruitment and receptor function.
Abstract: GPR84 is an understudied rhodopsin-like class A G protein-coupled receptor which is arousing particular interest from a therapeutic perspective. Not least this reflects that gpr84 expression is significantly up-regulated following acute inflammatory stimuli and in inflammatory diseases and that receptor activation plays a role in regulating pro-inflammatory responses and migration of cells of the innate immune system such as neutrophils, monocytes, macrophages and microglia. Although most physiological responses of GPR84 reflect receptor coupling to Gαi/o -proteins, several studies indicate that agonist-activated GPR84 can also recruit arrestin adaptor proteins and this regulates receptor internalisation and desensitisation. To date, little is known on the patterns of either basal or ligand regulated GPR84 phosphorylation and how these might control these processes. Here, we consider what is known about the regulation of GPR84 signalling with a focus on how G protein receptor kinase -mediated phosphorylation regulates arrestin protein recruitment and receptor function.
TL;DR: In this article , a high-resolution structure of the GPR84-Gi signaling complex with 6-OAU was determined, which revealed a completely occluded binding pocket for 6-OU, the molecular basis of receptor activation involving nonconserved structural motifs of GPCR, and an unusual Gi-coupling interface.
Abstract: GPR84 is a unique orphan G protein-coupled receptor (GPCR) that can be activated by endogenous medium-chain fatty acids (MCFAs). The signaling of GPR84 is largely pro-inflammatory, which can augment inflammatory response, and GPR84 also functions as a pro-phagocytic receptor to enhance phagocytic activities of macrophages. In this study, we first showed that the activation of GPR84 by the synthetic agonist 6-OAU could synergize with the blockade of CD47 on cancer cells to induce phagocytosis of cancer cells by macrophages. Then, we determined a high-resolution structure of the GPR84-Gi signaling complex with 6-OAU. This structure revealed a completely occluded binding pocket for 6-OAU, the molecular basis of receptor activation involving non-conserved structural motifs of GPR84, and an unusual Gi-coupling interface. Together with computational docking and simulations studies, our structure also suggested the mechanism for the high selectivity of GPR84 for MCFAs and the potential routes of ligand binding and dissociation. Our results provide a framework for understanding GPR84 signaling and developing new drugs targeting GPR84.