Exploring novel A2AAR antagonists: Design, synthesis, and evaluation of 2,6,9-trisubstituted purine derivatives as promising antifibrotic agents.

A series of 2,6,9-trisubstituted purine derivatives were designed and synthesized with diverse chemical moieties. Through a comprehensive biological evaluation, we identified 4-(6-(methylamino)-2-(phenylethynyl)-9H-purin-9-yl)phenol (6a) as a promising A2AAR antagonist with potent antifibrotic properties. Compound 6a demonstrated significant efficacy in inhibiting CRE promoter activity and in reducing the expression of fibrogenic marker proteins and downstream effectors of A2AAR activation, surpassing the A2AAR antagonist ZM241385 and initial screening hits, 9-benzyl-N-methyl-2-(phenylethynyl)-9H-purin-6-amine (5a) and 9-((benzyloxy)methyl)-N-methyl-2-(phenylethynyl)-9H-purin-6-amine (5j). Further validation revealed that compound 6a effectively inhibited fibrogenic marker proteins induced by A2AAR overexpression or TGF-ß1 treatment in hepatic stellate cells, alongside reducing PKA and CREB phosphorylation. These findings suggest that compound 6a exerts its antifibrotic action by modulating the cAMP/PKA/CREB pathway through A2AAR inhibition. Overall, our study provides valuable insights for the development of novel therapeutics that target hepatic fibrosis through A2AAR antagonism.

A novel A2a adenosine receptor inhibitor effectively mitigates hepatic fibrosis in a metabolic dysfunction-associated steatohepatitis mouse model.

Hepatic fibrosis exacerbates mortality and complications in progressive metabolic dysfunction-associated steatohepatitis (MASH). The role of the adenosine 2A receptor (A2aAR) in hepatic fibrosis within the context of MASH remains uncertain. This study aims to elucidate the involvement of the A2aAR signaling pathway and the efficacy of a novel potent A2aAR antagonist in treating hepatic fibrosis in MASH-induced mice fed a chlorine-deficient, L-amino acid-defined, high fat diet (CDAHFD). A2aAR overexpression in LX-2 cells increased fibrosis markers, whereas the known A2aAR antagonist, ZM241385, decreased these markers. A novel A2aAR antagonist, RAD11, not only attenuated fibrosis progression but also exhibited greater inhibition of the A2aAR signaling pathway compared to ZM241385 in mice with MASH, activated primary hepatocytes, and LX-2 cells. RAD11 exhibited a dual antifibrotic mechanism by targeting both activated HSCs and hepatocytes. Its superior antifibrotic efficacy over ZM241385 in the MASH condition stems from its ability to suppress A2aAR-mediated signaling, inhibit HSC activation, reduce hepatic lipogenesis in hepatocytes, and mitigate lipid accumulation-induced oxidative stress-mediated liver damage. This study has shed light on the relationship between A2aAR signaling and hepatic fibrosis, presenting RAD11 as a potent therapeutic agent for managing MASH and hepatic fibrosis.

Antioxidative Hyaluronic Acid-Bilirubin Nanomedicine Targeting Activated Hepatic Stellate Cells for Anti-Hepatic-Fibrosis Therapy.

Liver fibrosis is a life-threatening and irreversible disease. The fibrosis process is largely driven by hepatic stellate cells (HSCs), which undergo transdifferentiation from an inactivated state to an activated one during persistent liver damage. This activated state is responsible for collagen deposition in liver tissue and is accompanied by increased CD44 expression on the surfaces of HSCs and amplified intracellular oxidative stress, which contributes to the fibrosis process. To address this problem, we have developed a strategy that combines CD44-targeting of activated HSCs with an antioxidative approach. We developed hyaluronic acid-bilirubin nanoparticles (HABNs), composed of endogenous bilirubin, an antioxidant and anti-inflammatory bile acid, and hyaluronic acid, an endogenous CD44-targeting glycosaminoglycan biopolymer. Our findings demonstrate that intravenously administered HABNs effectively targeted the liver, particularly activated HSCs, in fibrotic mice with choline-deficient l-amino acid-defined high-fat diet (CD-HFD)-induced nonalcoholic steatohepatitis (NASH). HABNs were able to inhibit HSC activation and proliferation and collagen production. Furthermore, in a murine CD-HFD-induced NASH fibrosis model, intravenously administered HABNs showed potent fibrotic modulation activity. Our study suggests that HABNs have the potential to serve as a targeted anti-hepatic-fibrosis therapy by modulating activated HSCs via CD44-targeting and antioxidant strategies. This strategy could also be applied to various ROS-related diseases in which CD44-overexpressing cells play a pivotal role.

Hypoxia-induced ELF3 promotes tumor angiogenesis through IGF1/IGF1R.

Epithelial ovarian cancer (EOC) is one of the most lethal gynecological cancers despite a relatively low incidence. Angiogenesis, one of the hallmarks of cancer, is essential for the pathogenesis of EOC, which is related to the induction of angiogenic factors. We found that ELF3 was highly expressed in EOCs under hypoxia and functioned as a transcription factor for IGF1. The ELF3-mediated increase in the secretion of IGF1 and VEGF promoted endothelial cell proliferation, migration, and EOC angiogenesis. Although this situation was much exaggerated under hypoxia, ELF3 silencing under hypoxia significantly attenuated angiogenic activity in endothelial cells by reducing the expression and secretion of IGF1 and VEGF. ELF3 silencing attenuated angiogenesis and tumorigenesis in ex vivo and xenograft mouse models. Consequently, ELF3 plays an important role in the induction of angiogenesis and tumorigenesis in EOC as a transcription factor of IGF1. A detailed understanding of the biological mechanism of ELF3 may both improve current antiangiogenic therapies and have anticancer effects for EOC.