Discovery of new LXRβ agonists as glioblastoma inhibitors

Truncated pyridinylbenzylamines: Potent, selective, and highly membrane permeable inhibitors of human neuronal nitric oxide synthase

Neuronal nitric oxide synthase (nNOS) is a promising target for addressing various neurological disorders and melanoma. Our discovery of a series of truncated pyridinylbenzylamines has yielded potent, selective, and membrane permeable inhibitors of human neuronal nitric oxide synthase. By implementing an efficient synthetic procedure using the Suzuki-Miyaura cross-coupling reaction, we were able to rapidly identify a potent inhibitor. This new inhibitor (18, 6-(2,3-difluoro-5-((methylamino)methyl)phenyl)-4-methylpyridin-2-amine dihydrochloride) exhibits excellent potency, with Ki values of 30 nM for human nNOS and 40 nM for rat nNOS. It also demonstrates high isoform selectivity, showing an 821-fold preference for human nNOS over human endothelial NOS (eNOS) and a 75-fold selectivity over human inducible NOS (iNOS). Additionally, inhibitor 18 displays high permeability (Pe = 10.7 × 10-6 cm s-1) in an artificial membrane permeability assay. The crystal structures of several NOS-inhibitor complexes provide valuable structural insights into the potency and selectivity of this series of novel inhibitors. A particularly notable finding is the unexpected role of a Cl- anion bound to heNOS, which contributes to the high isoform selectivity of these inhibitors and explains why heNOS binds Cl-, while hnNOS does not. This unique Cl- binding site could be important in future inhibitor design, opening new avenues for the development of more selective NOS inhibitors. Additionally, the presented crystal structures reveal the key factors required to maintain both high potency and selectivity in the simplified inhibitors discussed in this study. Abbreviations: NO, nitric oxide; nNOS, neuronal nitric oxide synthase; iNOS, inducible nitric oxide synthase; eNOS, endothelial nitric oxide synthase; rnNOS, rat neuronal nitric oxide synthase; hnNOS, human neuronal nitric oxide synthase; hiNOS, human inducible nitric oxide synthase; heNOS, human endothelial nitric oxide synthase; l-Arg, l-arginine; NADPH, reduced nicotinamide adenine dinucleotide phosphate; CaM, calmodulin; H4B, (6R)-5,6,7,8-tetrahydrobiopterin; FAD, flavin adenine dinucleotide; FMN, Flavin mononucleotide, BBB, blood-brain barrier; CNS, central nervous system; PAMPA, parallel artificial membrane permeability assay; P-gp, P-glycoprotein; ER, efflux ratio; Pe, effective permeability; Papp, apparent permeability; Caco-2, cancer coli-2; TLC, thin layer chromatography; TBAF, tetra-n-butylammonium fluoride; TFA, trifluoroacetic acid.

Artificial Intelligence-Assisted Drug and Biomarker Discovery for Glioblastoma: A Scoping Review of the Literature

Background: Artificial intelligence (AI) has emerged as a transformative tool in healthcare, particularly in drug and biomarker discovery, where it can enhance precision, streamline discovery processes, and optimize treatment strategies. Despite its potential, the application of AI in glioblastoma (GB) research, especially in identifying novel biomarkers and therapeutic targets, remains underexplored. The aim of this review is to map the existing literature on AI-driven approaches for biomarker and drug discovery in GB, highlighting key trends and gaps in current research. Design: Following a PRISMA methodology, this scoping review examined studies published between 2012 and 2024. Searches were conducted across multiple databases, including MEDLINE (PubMed), Scopus, the Cochrane Library, and Web of Science (WOS). Eligible studies were screened, and relevant data were extracted and synthesized to provide a comprehensive overview of AI applications in GB research. Results: A total of 224 records were identified, including 210 from PubMed, 104 from Scopus, 4 from WOS, and 6 from the Cochrane Library. After screening and applying eligibility criteria, 33 studies were included in the final review. These studies showcased diverse AI methodologies applied to both drug discovery and biomarker identification, focusing on various aspects of GB biology and treatment. Conclusions: This scoping review reveals an increasing interest in AI-driven strategies for biomarker and drug discovery in GB, with promising initial results. However, further large-scale, rigorous studies are needed to validate real-world applications of AI and the development of standardized protocols to enhance reproducibility and clinical translation.

Research status and hotspots on the mechanisms of liver X receptor in cancer progression: A bibliometric analysis

BACKGROUND

The mechanism of liver X receptor in cancer has been gradually revealed in recent years. This study is committed to analyzing the current research status of the mechanism of liver × receptor in cancer progression by using bibliometric methods and to explore the development trend of liver × receptor related research in the future, in order to provide some reference for further exploration in this field.

METHODS

The Web of Science core collection database was used to carry out the original data retrieval. Excel software was used for data statistics. Vosviewer and CiteSpace software were used to analyze the publication situation, cooperation network, reference co-citation, keyword and term co-occurrence, term bursts, and cluster analysis, and draw visual maps.

RESULTS

A total of 631 publications meeting the research criteria were included by December 2022, with an average of 32.5 citations per paper. The main research fields were molecular biology, oncology and cell biology, and the papers were mainly published in journals about molecular, biology and immunology. Cell is the journal with the highest citation. The United States is the most influential country, the University of California, Los Angeles is the main research institution, and Gustafsson, Jan-ake is the author with the highest output. In reference co-citation clustering, cluster#2 "cancer development" is the main cluster, and the period from 2014 to 2018 is an important stage of relevant theoretical progress. "Tumor microenvironment" with high burst and novelty became the most noteworthy term in term burst.

CONCLUSION

Using bibliometric methods to reveal the current status of LXR and cancer mechanisms, and making predictions of possible future hotspots based on the analysis of the current situation, the translation of LXR anti-cancer research to clinical applications, the impact on the tumor microenvironment as a whole and more immune pathways, and the formation of a systematic cognition of the effects of more cancer cell lines and oncogenic signaling crosstalk, which is a possible direction for future research.

Liver X Receptors (LXRs) in cancer-an Eagle's view on molecular insights and therapeutic opportunities

Cancer has become a serious health burden that results in high incidence and mortality rates every year, mainly due to various molecular alterations inside the cell. Liver X receptors (LXRs) dysregulation is one among them that plays a vital role in cholesterol metabolism, lipid metabolism and inflammation and also plays a crucial role in various diseases such as obesity, metabolic dysfunction-associated fatty liver disease (MAFLD), cardiovascular diseases, Type 2 diabetes, osteoporosis, and cancer. Studies report that the activation of LXRs inhibits cancer growth by inhibiting cellular proliferation, inducing apoptosis and autophagy, regulating cholesterol metabolism, various signalling pathways such as Wnt, and PI3K/AKT, modulating the expression levels of cell-cycle regulators, and promoting antitumor immunity inside the tumor microenvironment. In this review, we have discussed the role, structure, and functions of LXRs and also summarized their ligands along with their mechanism of action. In addition, the role of LXRs in various cancers, tumor immunity and tumor microenvironment (TME) along with the importance of precision medicine in LXR-targeted therapies has been discussed to emphasize the LXRs as potent targets for the development of novel cancer therapeutics.

A structural perspective of liver X receptors

Liver X receptors α and β are members of the nuclear receptor family, which comprise a flexible N-terminal domain, a DNA binding domain, a hinge linker, and a ligand binding domain. Liver X receptors are important regulators of cholesterol and lipid homeostasis by controlling the transcription of numerous genes. Key to their transcriptional role is synergetic interaction among the domains. DNA binding domain binds on DNA; ligand binding domain is a crucial switch to control the transcription activity through conformational change caused by ligand binding. The Liver X receptors form heterodimers with retinoid X receptor and then the liganded heterodimer may recruit other necessary transcription components to form an active transcription complex.

Discovery of Spiro[pyrrolidine-3,3'-oxindole] LXRβ Agonists for the Treatment of Osteoporosis

Osteoclasts have an additional demand for cholesterol compared to normal cells. Liver X receptors (LXRs) are famous for regulation of lipid and cholesterol metabolism. Therefore, we propose that the LXR β agonist can regulate the cholesterol balance in osteoclasts to inhibit osteoclast differentiation. Here, we designed and synthesized a novel LXRβ agonist by introduction of the privileged fragments from anti-osteoporosis agents to the spiro[pyrrolidine-3,3'-oxindole] scaffold which is a novel scaffold of LXR agonists in our previous research. As a result, seven LXRβ agonists inhibited osteoclastogenesis with IC₅₀ values ranging from 0.078 to 0.36 μM. Especially, the most potent LXRβ agonist B9 significantly inhibited RANKL-induced osteoclast differentiation and bone resorption in vitro and in vivo. Furthermore, B9 selectively activated LXRβ to promote intracellular cholesterol exclusion in osteoclasts and reduce extracellular cholesterol uptake and thereby inhibited osteoclast production. This study provides a new strategy to develop LXRβ agonists for osteoporosis.

Glioblastoma: Current Status, Emerging Targets, and Recent Advances

Glioblastoma (GBM) is a highly malignant brain tumor characterized by a heterogeneous population of genetically unstable and highly infiltrative cells that are resistant to chemotherapy. Although substantial efforts have been invested in the field of anti-GBM drug discovery in the past decade, success has primarily been confined to the preclinical level, and clinical studies have often been hampered due to efficacy-, selectivity-, or physicochemical property-related issues. Thus, expansion of the list of molecular targets coupled with a pragmatic design of new small-molecule inhibitors with central nervous system (CNS)-penetrating ability is required to steer the wheels of anti-GBM drug discovery endeavors. This Perspective presents various aspects of drug discovery (challenges in GBM drug discovery and delivery, therapeutic targets, and agents under clinical investigation). The comprehensively covered sections include the recent medicinal chemistry campaigns embarked upon to validate the potential of numerous enzymes/proteins/receptors as therapeutic targets in GBM.

Recent in vivo advances of spirocyclic scaffolds for drug discovery

INTRODUCTION

Spirocyclic scaffolds are an exceptional tool in drug design, allowing fine-tuning of a molecule's conformational and physicochemical properties. As it expands and diversifies, so does the number of therapeutics that contain this core. Several spirocyclic drugs are already marketed, and considerably more have shown promising results.

AREAS COVERED

This review addresses recent in vivo studies (2017-2021) on applying spirocyclic compounds to treat various diseases, mainly grouped within neurological, infectious, and metabolic diseases and cancer. An emphasis is given on the influence of the spiro-structure on activity and consequent structure-activity study. In vivo results and their significance in the future progression towards clinical trials are also presented.

EXPERT OPINION

Spirocyclic compounds present an exciting opportunity as an unexplored chemical space in medicinal chemistry. However, their development is hindered by their complexity and synthesis challenges. Furthermore, a clear preference is still seen for readily available spirocyclic compounds involving amine or amide bonds. Nevertheless, these are temporary as high-throughput synthesis, and computational techniques allow fast optimization studies. In our opinion, the field of spirocyclic chemistry will continue to thrive and contribute to drug development, improving activity and selectivity on emergent ailments, such as cancer, metabolic, infectious, and neurological diseases.

Oncological drug discovery: AI meets structure-based computational research

The integration of machine learning and structure-based methods has proven valuable in the past as a way to prioritize targets and compounds in early drug discovery. In oncological research, these methods can be highly beneficial in addressing the diversity of neoplastic diseases portrayed by the different hallmarks of cancer. Here, we review six use case scenarios for integrated computational methods, namely driver prediction, computational mutagenesis, (off)-target prediction, binding site prediction, virtual screening, and allosteric modulation analysis. We address the heterogeneity of integration approaches and individual methods, while acknowledging their current limitations and highlighting their potential to bring drugs for personalized oncological therapies to the market faster.

Structural overview and perspectives of the nuclear receptors, a major family as the direct targets for small-molecule drugs

The nuclear receptors (NRs) are an evolutionarily related family of transcription factors, which share certain common structural characteristics and regulate the expressions of various genes by recognizing different response elements. NRs play important roles in cell differentiation, proliferation, survival and apoptosis, rendering them indispensable in many physiological activities including growth and metabolism. As a result, dysfunctions of NRs are closely related to a variety of diseases, such as diabetes, obesity, infertility, inflammation, the Alzheimer's disease, cardiovascular diseases, prostate and breast cancers. Meanwhile, small-molecule drugs directly targeting NRs have been widely used in the treatment of above diseases. Here we summarize recent progress in the structural biology studies of NR family proteins. Compared with the dozens of structures of isolated DNA-binding domains (DBDs) and the striking more than a thousand of structures of isolated ligand-binding domains (LBDs) accumulated in the Protein Data Bank (PDB) over thirty years, by now there are only a small number of multi-domain NR complex structures, which reveal the integration of different NR domains capable of the allosteric signal transduction, or the detailed interactions between NR and various coregulator proteins. On the other hand, the structural information about several orphan NRs is still totally unavailable, hindering the further understanding of their functions. The fast development of new technologies in structural biology will certainly help us gain more comprehensive information of NR structures, inspiring the discovery of novel NR-targeting drugs with a new binding site beyond the classic LBD pockets and/or a new mechanism of action.

Essential Oils from Spices Inhibit Cholinesterase Activity and Improve Behavioral Disorder in AlCl3 Induced Dementia

The chemical compositions of essential oils (EOs) prepared from six spices including cinnamon, amomum tsao-ko, cardamom, amomum, black pepper and white pepper were analyzed by gas chromatography-mass spectrometry (GC/MS), which led to identify almost 200 volatile compounds. All EOs of spices showed cholinesterase inhibitory activity. Among them, pepper EO showed most potent acetylcholinesterase (AChE) inhibitory activity with IC₅₀ values of 8.54 μg/mL (black pepper EO) and 5.02 μg/mL (white pepper EO). Molecular docking and in vitro validation suggested that 3-carene, α-pinene and β-pinene with IC₅₀ value of 1.73, 2.66, and 14.75 μg/mL, respectively, might be active constituents of spices oil in inhibiting AChE. Furthermore, amomum tsao-ko EO and amomum EO can improve behavioral disorder in dementia zebrafish induced by aluminum trichloride (AlCl₃ ).

Uncurtaining the pivotal role of ABC transporters in diabetes mellitus

The metabolic disorders are the edge points for the initiation of various diseases. These disorders comprised of several diseases including diabetes, obesity, and cardiovascular complications. Worldwide, the prevalence of these disorders is increasing day by day. The world's population is at higher threat of developing metabolic disease, especially diabetes. Therefore, there is an impregnable necessity of searching for a newer therapeutic target to reduce the burden of these disorders. Diabetes mellitus (DM) is marked with the dysregulated insulin secretion and resistance. The lipid and glucose transporters portray a pivotal role in the metabolism and transport of both of these. The excess production of lipid and glucose and decreased clearance of these leads to the emergence of DM. The ATP-binding cassette transporters (ABCT) are important for the metabolism of glucose and lipid. Various studies suggest the key involvement of ABCT in the pathologic process of different diseases. In addition, the involvement of other pathways, including IGF signaling, P13-Akt/PKC/MAPK signaling, and GLP-1 via regulation of ABCT, may help develop new treatment strategies to cope with insulin resistance dysregulated glucose metabolism, key features in DM.

Liver X receptors and skeleton: Current state-of-knowledge

The liver X receptors (LXR) is a nuclear receptor that acts as a prominent regulator of lipid homeostasis and inflammatory response. Its therapeutic effectiveness against various diseases like Alzheimer's disease and atherosclerosis has been investigated in detail. Emerging pieces of evidence now reveal that LXR is also a crucial modulator of bone remodeling. However, the molecular mechanisms underlying the pharmacological actions of LXR on the skeleton and its role in osteoporosis are poorly understood. Therefore, in the current review, we highlight LXR and its actions through different molecular pathways modulating skeletal homeostasis. The studies described in this review propound that LXR in association with estrogen, PTH, PPARγ, RXR hedgehog, and canonical Wnt signaling regulates osteoclastogenesis and bone resorption. It regulates RANKL-induced expression of c-Fos, NFATc1, and NF-κB involved in osteoclast differentiation. Additionally, several studies suggest suppression of RANKL-induced osteoclast differentiation by synthetic LXR ligands. Given the significance of modulation of LXR in various physiological and pathological settings, our findings indicate that therapeutic targeting of LXR might potentially prevent or treat osteoporosis and improve bone quality.

Identifying selective agonists targeting LXRβ from terpene compounds of alismatis rhizoma

Hyperlipidemia is thought of as an important contributor to coronary disease, diabetes, and fatty liver. Liver X receptor β (LXRβ) was considered as a validated target for hyperlipidemia therapy due to its role in regulating cholesterol homeostasis and immunity. However, many current drugs applied in clinics are not selectively targeting LXRβ, and they can also activate LXRα which activates SREBP-1c that worked as an activator of lipogenic genes. Therefore, exploiting agonists selectively targeting LXRβ is urgent. Here, computational tools were used to screen potential agonists selectively targeting LXRβ from 112 terpenes of alismatis rhizoma. Firstly, a structural analysis between selective and nonselective agonists was used to explore key residues of selective binding with LXRβ. Our data indicated that Phe²⁷¹, Ser²⁷⁸, Met³¹², His⁴³⁵, and Trp⁴⁵⁷ were important to compounds binding with LXRβ, suggesting that engaging ligand interaction with these residues may provide directions for the development of ligands with improved selective profiles. Then, ADMET analysis, molecular docking, MD simulations, and calculation of binding free energy and its decomposition were executed to screen the agonists whose bioactivity was favorable from 112 terpenes of alismatis rhizoma. We found that two triterpenes 16-hydroxy-alisol B 23-acetate and alisol M 23-acetate showed favorable ADMET properties and high binding affinity against LXRβ. These compounds could be considered as promising selective agonists targeting LXRβ. Our work provides an alternative strategy for screening agonists selectively targeting LXRβ from alismatis rhizoma for hyperlipidemia disease treatment.