Discovery of a small-molecule bromodomain-containing protein 4 inhibitor that induces AMP-activated protein kinase-modulated autophagy-associated cell death in breast cancer

OBJECTIVE To discover a small-molecule bromodomain-containing protein 4(BRD4)inhibitor that induces AMP-activated protein kinase-modulated autophagy-associated cell death in breast cancer and exploreits potential mechanisms.METHODS BRD4 interactors were analyzed by PPI network prediction and The Cancer Genome Atlas(TCGA)analysis.The interaction between BRD4 and AMPK was confirmed by co-immunoprecipitation assay.Novel BRD4 inhibitors were designed and synthesized based upon pharmacophore analysis of BRD4(1),then screened by antiproliferative activity and Alpha Screen of BRD4(1).The selectivity of the best candidate compound 8f was validated by co-crystallization,FRET assay and co-immuno precipitation assay.The mechanisms of 8f were investigated by fluorescence microscopy,electron microscopy,Western blotting,immunocytochemistry,si RNA and GFP-m RFP-LC3 plasmid transfections,as well as immunohistochemistry and immunofluorescence.Potential mechanisms were discovered by i TRAQ-based proteomics analysis and the therapeutic effect of 8f was assessed by xenograft breast cancer mouse and zebrafish models.RESULTS We identified that BRD4 interacted with AMPK,which was remarkably downregulated in breast cancer.We next designed and synthesized 49 candidate compounds,and eventually discovered a selective small-molecule inhibitor of BRD4(8f).Subsequently,8f was discovered to induce autophagyassociated cell death(ACD)by BRD4-AMPK interaction,and thus activating AMPK-m TOR-ULK1-modulated autophagic pathway in breast cancer cells.Interestingly,the i TRAQ-based proteomics analyses revealed that 8f induced ACD pathways,involved in HMGB1,VDAC1/2 and e EF2.Moreover,8f displayed a therapeutic potential on both xenograft breast cancer mouse and zebrafish models.CONCLUSION We discovered a novel small-molecule inhibitor of BRD4 that induces BRD4-AMPK-modulated ACD in breast cancer,which may provide a candidate drug for future cancer therapy.

Efficient small-molecule donor with improved structural order and molecular aggregation enabled by side-chain modification

Side-chain modification is a proven effective approach for morphology manipulation in organic solar cells(OSCs).However,in-depth analysis and investigation involving side-chain modification towards morphology improvement,including molecular microstructure,orientating packing and aggregation are urgent for all-small-molecule(ASM)systems.Herein,employing a fluorine-modified two-dimension benzodithiophene(BDT)as central unit,we contrastively synthesized two small-molecule donors,namely BDT-F-SR and BDT-F-R,each welding alkylthio side-chains on thienyl of central BDT unit and the other grafted non-sulfuric alkyl side-chains.As predicted,the synergetic side-chain modification of fluorination and alkyl changeover triggers diverse molecular dipole moments and orientations,resulting in different molecular energy levels,thermal stabilities,molecular planarity and order.Eventually,together with the preeminent small-molecule acceptor Y6,BDT-F-R-based ASM OSCs obtain enhanced power conversion efficiency(PCE)of 13.88%compared to BDT-F-SR-based devices(PCE of 12.75%)with more suitable phase-separation and balanced carrier mobilities.The contrast results reveal that alkyl sidechains seem to be a more satisfactory partner for fluorine-modified 2D BDT-based small-molecule donors compared to alkylthio pendants,and highlight the significance of subtle side-chain modification for molecular structural order fun-tuning and morphology control,laying the foundation for efficient ASM OSCs.

Design,synthesis,and evaluation of fluoroquinolone derivatives as microRNA-21 small-molecule inhibitors

MicroRNA-21(miRNA-21)is highly expressed in various tumors.Small-molecule inhibition of miRNA-21 is considered to be an attractive novel cancer therapeutic strategy.In this study,fluoroquinolone derivatives A1eA43 were synthesized and used as miRNA-21 inhibitors.Compound A36 showed the most potent inhibitory activity and specificity for miRNA-21 in a dual-luciferase reporter assay in HeLa cells.Compound A36 significantly reduced the expression of mature miRNA-21 and increased the protein expression of miRNA-21 target genes,including programmed cell death protein 4(PDCD4)and phosphatase and tensin homology deleted on chromosome ten(PTEN),at 10 μM in HeLa cells.The Cell Counting Kit-8 assay(CCK-8)was used to evaluate the antiproliferative activity of A36;the results showed that the IC_(50) value range of A36 against six tumor cell lines was between 1.76 and 13.0 μM.Meanwhile,A36 did not display cytotoxicity in BEAS-2B cells(lung epithelial cells from a healthy human donor).Furthermore,A36 significantly induced apoptosis,arrested cells at the G_(0)/G_(1) phase,and inhibited cell-colony formation in HeLa cells.In addition,mRNA deep sequencing showed that treatment with A36 could generate 171 dysregulated mRNAs in HeLa cells,while the expression of miRNA-21 target gene dual-specificity phosphatase 5(DUSP5)was significantly upregulated at both the mRNA and protein levels.Collectively,these findings demonstrated that A36 is a novel miRNA-21 inhibitor.

Small-Molecule Ligands as Challenge for Positron Emission Tomography of Peptide Receptors in Neurons and Microglia of the Brain

Neuropeptide and chemokine receptors of the G protein-coupled receptor (GPCR) family belong to different classes and subgroups providing different docking sites and special binding behavior at extracellular and also transmembrane domains for small molecules potentially suitable for positron emission tomography (PET). The contribution gives an overview updating developments of small-molecule, nonpeptide ligands at a selection of peptide and chemokine receptors, expressed in neurons and microglia of the brain, regarding the last five years. Orexin 1 and orexin 2 receptors (OX1R;OX2R) and neuropeptide Y1 and Y2 receptors (NPY1R, NPY2R) were chosen as representatives of Class A neuropeptide receptors, chemokine receptor CX3C (CX3CR1) as Class A, protein-activated receptor, highly expressed in activated microglia, and corticotropin releasing factor receptor 1 (CRFR1) as representative Class B1 receptor. Structural differences between binding domains and their endogenous ligands as well as parallel expression in different types of cells and generally low density of these receptors in brain tissue are factors making the search for selective and sensitive ligands more difficult than for classical GPCR receptors. Main progress in ligand development is observed for NPY receptor antagonists and orexin receptor antagonists. For orexin receptors, search for suitable ligands can be supported with modelling approaches, as recently the complete molecular structure of these receptors is available. Small molecules, binding at CRFR1, as for other Class B1 receptor ligands, in PET and investigations of pharmacodynamics revealed rather allosteric binding modes, although, the complete crystal structure of CRFR1 as prototype of Class B1 provides, hitherto, improved possibilities for understanding binding mechanisms. Highly specific as a marker of microglia among?the GPCRs, CX3CR1 is focused as target of PET during inflammation of brain and spinal cord.

Small-molecule agents for cancer immunotherapy

Cancer immunotherapy,exemplified by the remarkable clinical benefits of the immune checkpoint blockade and chimeric antigen receptor T-cell therapy,is revolutionizing cancer therapy.They induce long-term tumor regression and overall survival benefit in many types of cancer.With the advances in our knowledge about the tumor immune microenvironment,remarkable progress has been made in the development of small-molecule drugs for immunotherapy.Small molecules targeting PRR-associated pathways,immune checkpoints,oncogenic signaling,metabolic pathways,cytokine/chemokine signaling,and immune-related kinases have been extensively investigated.Monotherapy of smallmolecule immunotherapeutic drugs and their combinations with other antitumor modalities are under active clinical investigations to overcome immune tolerance and circumvent immune checkpoint inhibitor resistance.Here,we review the latest development of small-molecule agents for cancer immunotherapy by targeting defined pathways and highlighting their progress in recent clinical investigations.

Photocatalytic synthesis of small-molecule drugs by porous framework materials

Small-molecule drugs are widely used in daily life.There are still issues with the current industrial synthesis techniques for small-molecule drugs,such as the use of expensive metal catalysts,convoluted reaction processes,and non-recyclable catalysts.The benefits of photocatalytic organic synthesis over conventional techniques are mild conditions,environmental friendliness,and great selectivity.Porous framework materials can precisely modulate catalytic sites'electronic state and ligand structure to improve photocatalytic performance.In particular,MOFs,COFs and PCCs based photocatalysts have received extensive research interest due to their unique morphology,structural adjustability,high photocatalytic performance,unique recyclability,excellent chemical stability,easy synthesis and low cost.Therefore,a key area for future research is the development of porous framework materials as photocatalysts for the synthesis of small-molecule drugs or drug precursors.

Polymerized A-DA'D-A type small-molecule acceptors for high performance all-polymer solar cells: progress and perspective

A-DA'D-A type polymerized small-molecule acceptors(PSMAs) have very recently received wide attention because they possess advantages such as synthetic flexibility, narrowed bandgap, low energy loss, and impressive mechanical properties. With efforts on design and synthesis of PSMAs and polymer donors, significant progress has been made on all polymer solar cells(allPSCs) with power conversion efficiencies exceeding 18%. In this review, we focus on structure-property-performance relationships of the A-DA'D-A type PSMAs. First, we in-depth review the regio-random, regio-regular, and random ternary series by focusing on their structural modification such as from aspects of side-chains, halogenation, selenophene-containing and linkers, respectively. Second, we review the mechanically flexible and stretchable properties, which helps to find structural gene that correlates the mechanical properties. Third, we review the impressive small energy loss. In all, this review provides structural and material's clues, helpfully for designing high-performance all-PSCs.

Small-molecule organic electrode materials for rechargeable batteries

Small-molecule organic electrode materials(SMOEMs)have shown tremendous potential as cathodes or anodes for various rechargeable batteries including lithium and sodium batteries,due to their easy material availability,high structure designability,attractive theoretical capacity,and wide adaptability to counterions.However,they suffer from the severe dissolution problem and the subsequent shuttle effect in nonaqueous electrolytes,which cause the poor cycling stability and Coulombic efficiency.To satisfy the demands on the energy density and cycling stability simultaneously,the molecular structures of SMOEMs need to be rationally designed,and extrinsic approaches including electrode engineering and electrolyte optimizations can be further conducted.In this review,we summarize the fundamental knowledge about SMOEMs,including their working principles and applications,structure classifications,molecular structure design methods,and extrinsic optimization strategies.Moreover,we also provide some original insights aiming at guiding the research and development of SMOEMs in a more scientific and practical way.In brief,SMOEMs are facing huge opportunities and challenges as candidates to enable the next-generation of efficient,sustainable,and green rechargeable batteries.

Build in seconds:Small-molecule hydrogels of self-assembled tryptophan derivatives

Small-molecule hydrogels based on amino acid derivatives have promising applications in many biological fields,including cell culture,drug delivery,and tissue engineering.Although these hydrogels have been widely reported to have low cytotoxicity,biocompatibility,and tunable bioactivity,problems such as harsh preparation conditions and complex material design hinder their application.Herein,by adjusting pH to induce non-covalent interactions between small-molecule tryptophan derivatives(N-[(phenylmethoxy)carbonyl]-L-tryptophan,Mw:338.35),we developed a self-assembled three-dimensional network hydrogel that can be rapidly formed in seconds.And the supramolecular self-assembly mechanism of the hydrogels was also investigated in detail through experimental characterizations and density functional theory calculation.As-prepared hydrogels also exhibit reversible pH-stimulated response and self-healing properties.This study details a research process for the simple and rapid preparation of tryptophan derivative-based hydrogels,which provides more reference ideas for the future development of materials based on other amino acid derivatives.

Photo-Modulation of Gene-Editing Enzymes CRISPR/Cas9 with Bifunctional Small-Molecule Ligands

The control of protein functions with light is valuable for spatiotemporal probing of biological systems.Current small-molecule photo-modulation methods include the light-induced uncaging of inhibitors and chromophore-assisted light inactivation with reactive oxygen species(ROS).However,the constant target protein expression results in inadequate photo-modulation efficiency,particularly for less potent inhibitors and chromophores.Herein,we report a novel bifunctional small-molecule ligands strategy to photo-modulate gene-editing enzymes CRISPR/Cas9.A coumarin-derived small-molecule ligand Bhc-BRD0539 is developed to uncage the active inhibitor upon light irradiation and to generate ROS in the Cas9 proximity for the dual inhibition of Cas9 activity.Our results highlight the synergistic photo-modulation with bifunctional small-molecule ligands,which offers a valuable addition to current CRISPR/Cas9 photo-modulation technologies and may extend to other protein classes.

Efficient Small-Molecule Organic Solar Cells by Modulating Fluorine Substitution Position of Donor Material

Comprehensive Summary The fluorine substitution position in organic semiconductors is critical in improving device performance for organic solar cells(OSCs).Herein,two similar small-molecule donors,B3T-PoF and B3T-PmF,are designed and synthesized,which only differ on the fluorine substitution position on the pendent benzene unit.Although both small-molecule donors exhibit similar absorption profiles and molecular energy levels,B3T-PmF has stronger crystallinity and lower energetic disorder than B3T-PoF.After blending with the non-fullerene acceptor of BO-4Cl,B3T-PmF shows better phase separation and more ordered molecular packing in blend film.As a result,the B3T-PoF:BO-4Cl-based OSC shows a power conversion efficiency(PCE)of 12.3%.In contrast,the B3T-PmF:BO-4Cl-based cell demonstrates obviously increased JSC and FF values,thus yielding an excellent PCE of 14.7%.This study indicates that reasonable selection of fluorine atom substitution position in conjugated side chains is one of the promising strategies for achieving high-performance SM-DSCs.

A controllable self-localized imaging strategy capable of synchronous in situ tracking of local changes in intracellular bioactive small-molecules

In situ tracking and localization of ubiquitous bioactive small molecules(BSMs)within their native habitats is particularly challenging because of their low-molecular weight and widespread distribution properties.We report the proof of concept of a synchronous in situ imaging strategy,whereby the representative BSM amino-biothiols(ABs)mediate activation of the selflocalizable probe HYPQS,thereby releasing insoluble emissive precipitates to afford holistic distribution information of ABs.Notably,three organelle-targetable ABs inhibitors were innovatively fabricated for directed clearance of ABs in particular organelles,providing a powerful aid for HYPQS to achieve programmed in situ tracking of ABs in different organelles“on demand”.Biological transmission electron microscopy images confirmed that this probe released insoluble emissive precipitates at the reaction sites,which is of primary importance for achieving synchronous in situ tracking of BSMs.Furthermore,the probe HYPQS was successfully applied to monitor the dynamic changes in the endogenous ABs pool during diverse cell events.This strategy opens a promising avenue for investigating the undiscovered functional mechanism of local BSMs in relevant biological processes.

Small-molecule chemical probes for the potential therapeutic targets in alcoholic liver diseases

Alcoholic liver disease(ALD)encompasses a range of conditions resulting from prolonged and excessive alcohol consumption,causing liver damage such as alcoholic fatty liver,inflammation,fibrosis,and cirrhosis.Alcohol consumption contributes to millions of deaths each year.So far,the effective treatments for ALD are limited.To date,the most effective treatment for ALD is still prevention by avoiding excessive alcohol consumption,and only few specialized medicines are in the market for the treatment of patients suffering from ALD.Small molecules targeting various pathways implicated in ALD pathogenesis can potentially be used for effective therapeutics development.In this review,we provide a concise overview of the latest research findings on potential therapeutic targets,specifically emphasizing small-molecule interventions for the treatment and prevention of ALD.

Modulation of terminal alkyl chain length enables over 15% efficiency in small-molecule organic solar cells

In small-molecule organic solar cells(SM-OSCs),it remains a big challenge to obtain favorable bulk heterojunction morphology by donor material design.Herein,we design and synthesize three small-molecule donors BPF3T-C4,BPF3T-C6 and BPF3T-C8,with different terminal alkyl chains.Although they possess similar absorption profiles and molecular energy levels,their crystallinity gradually decreases with the chain length of the terminal alkyl chains.After blending with an electron acceptor of BO-4Cl,the crystallinity is suppressed and the packing orientations of these donors changed from edge-on to face-on.Simultaneously,the crystallinity of BO-4Cl is gradually weakened with the chain length of the terminal alkyl chain of donor materials.Finally,The BPF3T-C6 with moderate crystallinity exhibits the best phase-separation morphology among these blend films.As a result,the BPF3T-C6:BO-4Cl-based SM-OSC shows an impressive power conversion efficiency of 15.1%.

Targeting autophagy using small-molecule compounds to improve potential therapy of Parkinson’s disease

Parkinson’s disease(PD),known as one of the most universal neurodegenerative diseases,is a serious threat to the health of the elderly.The current treatment has been demonstrated to relieve symptoms,and the discovery of new small-molecule compounds has been regarded as a promising strategy.Of note,the homeostasis of the autolysosome pathway(ALP)is closely associated with PD,and impaired autophagy may cause the death of neurons and thereby accelerating the progress of PD.Thus,pharmacological targeting autophagy with small-molecule compounds has been drawn a rising attention so far.In this review,we focus on summarizing several autophagy-associated targets,such as AMPK,m TORC1,ULK1,IMPase,LRRK2,beclin-1,TFEB,GCase,ERRα,C-Abelson,and as well as their relevant small-molecule compounds in PD models,which will shed light on a clue on exploiting more potential targeted small-molecule drugs tracking PD treatment in the near future.

Development of small-molecule tropomyosin receptor kinase(TRK) inhibitors for NTRK fusion cancers

Tropomyosin receptor kinase A,B and C(TRKA,TRKB and TRKC),which are well-known members of the cell surface receptor tyrosine kinase(RTK)family,are encoded by the neurotrophic receptor tyrosine kinase 1,2 and 3(NTRK1,NTRK2 and NTRK3)genes,respectively.TRKs can regulate cell proliferation,differentiation and even apoptosis through the RAS/MAPKs,PI3 K/AKT and PLCγtyrosine kinase fusions;Small-molecule inhibitor;NTRK fusion cancer pathways.Gene fusions involving NTRK act as oncogenic drivers of a broad diversity of adult and pediatric tumors,and TRKs have become promising antitumor targets.Therefore,achieving a comprehensive understanding of TRKs and relevant TRK inhibitors should be urgently pursued for the further development of novel TRK inhibitors for potential clinical applications.This review focuses on summarizing the biological functions of TRKs and NTRK fusion proteins,the development of small-molecule TRK inhibitors with different chemotypes and their activity and selectivity,and the potential therapeutic applications of these inhibitors for future cancer drug discovery efforts.

Recent advances on small-molecule fluorophores with emission beyond 1000 nm for better molecular imaging in vivo

In the second near-infrared channel(NIR-II, 1000–1700 nm), organic and inorganic fluorophores are designed with superior chemical/optical properties to provide real-time information with deeper penetration depth and higher resolution owing to the innate lower light scattering and absorption of the NIR-II imaging than conventional optical imaging. Among them, the small-molecule based fluorophores have been highlighted due to their desirable biocompatibility and favorable pharmacokinetics. In this review, we introduced the latest research progress of the rational design of small-molecule NIR-II fluorophores and their impressively biological applications including the NIR-II signal imaging,multimodal imaging and theranostic.

Recent advances in developing small-molecule inhibitors against SARS-CoV-2

The COVID-19 pandemic caused by the novel SARS-CoV-2 virus has caused havoc across the entire world.Even though several COVID-19 vaccines are currently in distribution worldwide,with others in the pipeline,treatment modalities lag behind.Accordingly,researchers have been working hard to understand the nature of the virus,its mutant strains,and the pathogenesis of the disease in order to uncover possible drug targets and effective therapeutic agents.As the research continues,we now know the genome structure,epidemiological and clinical features,and pathogenic mechanism of SARS-CoV-2.Here,we summarized the potential therapeutic targets involved in the life cycle of the virus.On the basis of these targets,small-molecule prophylactic and therapeutic agents have been or are being developed for prevention and treatment of SARS-CoV-2 infection.

First small-molecule PROTACs for G protein-coupled receptors:inducing α1A-adrenergic receptor degradation

Proteolysis targeting chimeras(PROTACs)are dual-functional hybrid molecules that can selectively recruit an E3 ubiquitin ligase to a target protein to direct the protein into the ubiquitinproteasome system(UPS),thereby selectively reducing the target protein level by the ubiquitinproteasome pathway.Nowadays,small-molecule PROTACs are gaining popularity as tools to desrade pathogenic protein.Herein,we present the first small-molecule PROTACs that can induce the alA-adrenergic receptor(α1 A-AR)degradation,which is also the first small-molecule PROTACs for G proteincoupled receptors(GPCRs)to our knowledge.These degradation inducers were developed through conjugation of knownα1-adrenergic receptors(α1-ARs)inhibitor prazosin and cereblon(CRBN)ligand pomalidomide through the different linkers.The representative compound 9 c is proved to inhibit the proliferation of PC-3 cells and result in tumor growth regression,which highlighted the potential of our study as a new therapeutic strategy for prostate cancer.

Generation of liver bipotential organoids with a small-molecule cocktail

Understanding the mechanism of how cholangiocytes(liver ductal cells)are activated upon liver injury and specified to hepatocytes would permit liver regenerative medicine.Here we achieved long-term in vitro expansion of mouse liver organoids by modulating signaling pathways with a combination of three small-molecule compounds.CHIR-99021,blebbistatin,and forskolin together maintained the liver organoids in bipotential stage with both cholangiocyte-and hepatocyte-specific gene expression profiles and enhanced capacity for further hepatocyte differentiation.By employing a chemical approach,we demonstrated that Wnt/β-catenin,NMII-Rac,and PKA-ERK are core signaling pathways essential and sufficient for mouse liver progenitor expansion.Moreover,the advanced small-molecule culture of bipotential organoids facilitates the ex vivo investigation of liver cell fate determination and the application of organoids in liver regenerative medicine.