Discovery of the first potent and selective αvβ5 integrin inhibitor based on an amide-containing core

Generation of a biliary tract cancer cell line atlas reveals molecular subtypes and therapeutic targets

Biliary tract cancers (BTCs) are a group of deadly malignancies encompassing intrahepatic and extrahepatic cholangiocarcinoma, gallbladder carcinoma, and ampullary carcinoma. Here, we present the integrative analysis of 63 BTC cell lines via multi-omics clustering and genome- scale CRISPR screens, providing a platform to illuminate BTC biology and inform therapeutic development. We identify dependencies broadly enriched in BTC compared to other cancers as well as dependencies selective to the anatomic subtypes. Notably, cholangiocarcinoma cell lines are stratified into distinct lineage subtypes based on biliary or dual biliary/hepatocyte marker signatures, associated with dependency on specific lineage survival factors. Transcriptional analysis of patient specimens demonstrates the prognostic significance of these lineage subtypes. Additionally, we delineate strategies to enhance targeted therapies or to overcome resistance in cell lines with key driver gene mutations. Furthermore, clustering based on dependencies and proteomics data elucidates unexpected functional relationships, including a BTC subgroup with partial squamous differentiation. Thus, this cell line atlas reveals potential therapeutic targets in molecularly defined BTCs, unveils biologically distinct disease subtypes, and offers a vital resource for BTC research.

Exercise-induced muscle hormone "irisin" controls luteinizing hormone and follicle-stimulating hormone secretion by bovine gonadotrophs

Irisin is a hormone secreted by muscle in response to exercise. The irisin receptor (IrisinR) is a heterodimer of integrin alpha V (ITGAV) and integrin beta 5 (ITGB5) subunits. Since irisin may mediate some beneficial effects of exercise on animal reproduction, we tested the hypothesis that bovine gonadotrophs express IrisinR and irisin stimulates luteinizing hormone (LH) and follicle stimulating hormone (FSH) secretion by gonadotrophs. Reverse transcription polymerase chain reaction was used to detect the mRNA expression of both ITGAV and ITGB5 in the anterior pituitary glands (APs) of post pubertal heifers and mouse gonadotroph cell line "LβT2." Western blotting was used to detect protein expression in bovine APs. Immunofluorescence microscopy, utilizing the same antibody, visualized IrisinR on the plasma membrane of majority of gonadotrophs. We prepared AP cells from healthy postpubertal heifers, cultured them for 3.5 d, and treated them with increasing concentrations (0, 0.01, 0.1, 1, or 10 nM) of irisin for 5 min before either no treatment or gonadotropin-releasing hormone (GnRH) stimulation. After 2 h, media were harvested for LH and FSH assays. Irisin (0.1-10 nM) stimulated basal LH and FSH secretion, and these stimulatory effects were inhibited by the extracellular signal-regulated kinase or SMAD pathway inhibitors. In the presence of GnRH, irisin at 0.01-1 nM stimulated LH and FSH secretion. A higher dose of irisin (10 nM), however, suppressed the GnRH-induced LH and FSH levels. In conclusion, bovine gonadotrophs expressed IrisinR, and irisin controlled LH and FSH secretion from bovine gonadotrophs.

Inhibition of integrin alpha v/beta 5 mitigates the protective effect induced by irisin in hemorrhage

INTRODUCTION

Irisin plays an important role in regulating tissue stress, cardiac function, and inflammation. Integrin αvβ5 was recently identified as a receptor for irisin to elicit its physiologic function. It remains unknown whether integrin αvβ5 is required for irisin's function in modulating the physiologic response to hemorrhage. The objective of this study is to examine if integrin αvβ5 contributes to the effects of irisin during the hemorrhagic response.

METHODS

Hemorrhage was induced in mice by achieving a mean arterial blood pressure of 35-45 mmHg for one hour, followed by two hours of resuscitation. Irisin (0.5  μg/kg) was administrated to assess its pharmacologic effects in hemorrhage. Cilengitide, a cyclic Arg-Gly-Asp peptide (cRGDyK) which is an inhibitor of integrin αvβ5, or control RGDS (1 mg/kg) was administered with irisin. In another cohort of mice, the irisin-induced protective effect was examined after knocking down integrin β5 with nanoparticle delivery of integrin β5 sgRNA using CRSIPR/Cas-9 gene editing. Cardiac function and hemodynamics were measured using echocardiography and femoral artery catheterization, respectively. Systemic cytokine releases were measured using Enzyme-linked immunosorbent assay (ELISA). Histological analyses were used to determine tissue damage in myocardium, skeletal muscles, and lung tissues. Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) was carried out to assess apoptosis in tissues.

RESULTS

Hemorrhage induced reduction of integrin αvβ5 in skeletal muscles and repressed recovery of cardiac performance and hemodynamics. Irisin treatment led to significantly improved cardiac function, which was abrogated by treatment with Cilengitide or knockdown of integrin β5. Furthermore, irisin resulted in a marked suppression of tumor necrosis factor-α (TNF-α) and interleukin-1 (IL-1), muscle edema, and inflammatory cells infiltration in myocardium and skeletal muscles, which was attenuated by Cilengitide or knockdown of integrin β5. Irisin-induced reduction of apoptosis in the myocardium, skeletal muscles, and lung, which were attenuated by either the inhibition of integrin αvβ5, or knockdown of integrin β5.

CONCLUSION

Integrin αvβ5 plays an important role for irisin in modulating the protective effect during hemorrhage.

Irisin reduces inflammatory signaling pathways in inflammation-mediated metabolic syndrome

Irisin is an exercise induced myokine first shown to induce the browning of white adipose tissue (WAT) which increases energy expenditure, improves glucose tolerance, and reduces insulin resistance. Among irisin's involvement in lipid homeostasis, osteoblast proliferation, and muscle growth, it also acts as a mediator of many inflammatory pathways throughout the body. This review aims to describe the role of irisin in inflammatory processes and understand how targeting irisin can alter the inflammatory response in metabolic syndrome (MetS). The mechanisms involved in irisin's anti-inflammatory functions include reducing production of pro-inflammatory cytokines while increasing production of anti-inflammatory cytokines, reducing macrophage proliferation, inducing alternatively activated (M2-type) macrophage polarization, inhibiting pathways of increased vascular permeability, and preventing the formation of inflammasomes. While there are some contradictory results, most studies found reduced levels of irisin in MetS and type II diabetes mellitus (T2DM). Irisin treatment of cells exposed to inflammatory stimuli ameliorates the inflammatory response and promotes cellular viability. Numerous methods have been studied to increase plasma irisin levels including dietary, behavioral, and pharmaceutical. Further investigation is necessary to understand how irisin can be targeted for disease modification.

Integrins as a drug target in liver fibrosis

As the worldwide prevalence of chronic liver diseases is high and continuing to increase, there is an urgent need for treatment to prevent cirrhosis-related morbidity and mortality. Integrins are heterodimeric cell-surface proteins that are promising targets for therapeutic intervention. αv integrins are central in the development of fibrosis as they activate latent TGFβ, a known profibrogenic cytokine. The αv subunit can form heterodimers with β1, β3, β5, β6 or β8 subunits and one or more of these integrins are central to the development of liver fibrosis, however, their relative importance is not understood. This review summarises the current knowledge of αv integrins and their respective β subunits in different organs, with a focus on liver fibrosis and the emerging preclinical and clinical data with regards to αv integrin inhibitors.

Emerging therapeutic opportunities for integrin inhibitors

Integrins are cell adhesion and signalling proteins crucial to a wide range of biological functions. Effective marketed treatments have successfully targeted integrins αIIbβ3, α4β7/α4β1 and αLβ2 for cardiovascular diseases, inflammatory bowel disease/multiple sclerosis and dry eye disease, respectively. Yet, clinical development of others, notably within the RGD-binding subfamily of αv integrins, including αvβ3, have faced significant challenges in the fields of cancer, ophthalmology and osteoporosis. New inhibitors of the related integrins αvβ6 and αvβ1 have recently come to the fore and are being investigated clinically for the treatment of fibrotic diseases, including idiopathic pulmonary fibrosis and nonalcoholic steatohepatitis. The design of integrin drugs may now be at a turning point, with opportunities to learn from previous clinical trials, to explore new modalities and to incorporate new findings in pharmacological and structural biology. This Review intertwines research from biological, clinical and medicinal chemistry disciplines to discuss historical and current RGD-binding integrin drug discovery, with an emphasis on small-molecule inhibitors of the αv integrins.

Integrins are key signalling molecules that are present on the surface of subsets of cells and are therefore good potential therapeutic targets. In this Review, Hatley and colleagues discuss the development of integrin inhibitors, particularly the challenges in developing inhibitors for integrins that contain an αv-subunit, and suggest how these challenges could be addressed.

RGD-Binding Integrins Revisited: How Recently Discovered Functions and Novel Synthetic Ligands (Re-)Shape an Ever-Evolving Field

Simple Summary

Integrins, a superfamily of cell adhesion receptors, were extensively investigated as therapeutic targets over the last decades, motivated by their multiple functions, e.g., in cancer (progression, metastasis, angiogenesis), sepsis, fibrosis, and viral infections. Although integrin-targeting clinical trials, especially in cancer, did not meet the high expectations yet, integrins remain highly interesting therapeutic targets. In this article, we analyze the state-of-the-art knowledge on the roles of a subfamily of integrins, which require binding of the tripeptide motif Arg-Gly-Asp (RGD) for cell adhesion and signal transduction, in cancer, in tumor-associated exosomes, in fibrosis and SARS-CoV-2 infection. Furthermore, we outline the latest achievements in the design and development of synthetic ligands, which are highly selective and affine to single integrin subtypes, i.e., αvβ3, αvβ5, α5β1, αvβ6, αvβ8, and αvβ1. Lastly, we present the substantial progress in the field of nuclear and optical molecular imaging of integrins, including first-in-human and clinical studies.

Abstract

Integrins have been extensively investigated as therapeutic targets over the last decades, which has been inspired by their multiple functions in cancer progression, metastasis, and angiogenesis as well as a continuously expanding number of other diseases, e.g., sepsis, fibrosis, and viral infections, possibly also Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV-2). Although integrin-targeted (cancer) therapy trials did not meet the high expectations yet, integrins are still valid and promising targets due to their elevated expression and surface accessibility on diseased cells. Thus, for the future successful clinical translation of integrin-targeted compounds, revisited and innovative treatment strategies have to be explored based on accumulated knowledge of integrin biology. For this, refined approaches are demanded aiming at alternative and improved preclinical models, optimized selectivity and pharmacological properties of integrin ligands, as well as more sophisticated treatment protocols considering dose fine-tuning of compounds. Moreover, integrin ligands exert high accuracy in disease monitoring as diagnostic molecular imaging tools, enabling patient selection for individualized integrin-targeted therapy. The present review comprehensively analyzes the state-of-the-art knowledge on the roles of RGD-binding integrin subtypes in cancer and non-cancerous diseases and outlines the latest achievements in the design and development of synthetic ligands and their application in biomedical, translational, and molecular imaging approaches. Indeed, substantial progress has already been made, including advanced ligand designs, numerous elaborated pre-clinical and first-in-human studies, while the discovery of novel applications for integrin ligands remains to be explored.