Pharmacology of Adenosine Receptors: Recent Advancements

Role of A1 adenosine receptor in cardiovascular diseases: Bridging molecular mechanisms with therapeutic opportunities

Adenosine serves as a critical homeostatic regulator, exerting influence over physiological and pathological conditions in the cardiovascular system. During cellular stress, increased extracellular adenosine levels have been implicated in conferring cardioprotective effects through the activation of adenosine receptors with the A1 adenosine receptor subtype showing the highest expression in the heart. A1 adenosine receptor stimulation inhibits adenylyl cyclase activity via heterotrimeric Gi proteins, leading to the activation of distinct downstream effectors involved in cardiovascular homeostasis. While the comprehensive characterization of the pharmacological functions and intracellular signaling pathways associated with the A1 adenosine receptor subtype is still ongoing, this receptor is widely recognized as a crucial pharmacological target for the treatment of various states of cardiovascular diseases (CVDs). In this review, we focus on elucidating signal transduction of A1 adenosine receptor, particularly Gi protein-dependent and -independent pathways, and their relevance to cardiovascular protective effects as well as pathological consequences during cellular and tissue stresses in the cardiovascular system. Additionally, we provide comprehensive updates and detailed insights into a range of A1 adenosine receptor agonists and antagonists, detailing their development and evaluation through preclinical and clinical studies with a specific focus on their potential for the management of CVDs, especially heart diseases.

Ectonucleotidase inhibitors: an updated patent review (2017-2023)

INTRODUCTION

The main enzymes that hydrolyzes nucleotides at the cell surface are nucleoside triphosphate diphosphohydrolases (NTPDases), ecto-nucleotide pyrophosphatases/phosphodiesterases (ENPPs), alkaline phosphatases (APs) and ecto-5'- nucleotidase (e5'NT, CD73) and by regulating the concentration of nucleotides at the cell surface, these enzymes have the potential to affect various conditions such as fibrosis, cancer metastasis, pruritus, inflammation, and autoimmune diseases. Thus, they represent a prospective therapeutic target.

AREA COVERED

A number of molecules, including nucleoside/nucleotide and non-nucleoside analogues, and bicyclic compounds, have shown strong potential as ectonucleotidase inhibitors. This review covers the chemistry and clinical uses of ectonucleotidase inhibitors patented between 2017 and 2023.

EXPERT OPINION

By binding to their specific P1 and P2 receptors at the cell surface, nucleosides and nucleotides regulate a number of pathophysiological events such as inflammation, fibrosis, cancer, and autoimmune diseases. Interestingly, these nucleotides can be hydrolyzed to nucleosides by several cell surface enzymes called ectonucleotidases. The development of small molecules that modulate ectonucleotidase activity is, therefore, of therapeutic value. This review provides valuable insights into recent advancements, including combination therapy and enhanced selectivity, which are poised to shape the future of ectonucleotidase inhibition through a comprehensive analysis of patents.

Development of Preladenant-Based Radiotracers for Imaging A2AR in Tumors

Activation of the adenosine 2A receptor (A2AR) can lead to tumor immunosuppression, which results in poor prognosis of immunotherapy. The aim of this study was to design novel 18F-labeled probes ([18F]F-PFP2 and [18F]F-PFP4) to visualize A2AR in the tumor. The uptake of radioprobes in A2AR-negative 4T1 breast tumor was lower than that of A2AR-positive B16F10 melanoma at 1 h p.i. (1.22 ± 0.36% ID/g vs 2.80 ± 0.72% ID/g), 2 h p.i. (1.09 ± 0.20% ID/g vs 2.93 ± 0.76% ID/g) and 3 h p.i. (0.89 ± 0.27% ID/g vs 2.73 ± 0.58% ID/g), respectively. B16F10 lung metastasis models were employed to expand the application scenarios, observing significantly higher uptake of [18F]F-PFP2 in metastatic lesions compared to normal lung tissue (5.55 ± 2.18% ID/g vs 1.89 ± 0.65% ID/g, tumor/lung ratio ∼3). It is given that [18F]F-PFP2 might lay the foundation for establishing an A2AR-targeted imaging evaluation system for tumors, which will provide more precise guidance for personalized treatment.