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.

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 inhibitors of RORγt for Th17 regulation in inflammatory and autoimmune diseases

As a ligand-dependent transcription factor,retinoid-associated orphan receptor gt(RORγt)that controls T helper(Th)17 cell differentiation and interleukin(IL)-17 expression plays a critical role in the progression of several inflammatory and autoimmune conditions.An emerging novel approach to the therapy of these diseases thus involves controlling the transcriptional capacity of RORγt to decrease Th17 cell development and IL-17 production.Several RORγt inhibitors including both antagonists and inverse agonists have been discovered to regulate the transcriptional activity of RORγt by binding to orthosteric-or allosteric-binding sites in the ligand-binding domain.Some of small-molecule inhibitors have entered clinical evaluations.Therefore,in current review,the role of RORγt in Th17 regulation and Th17-related inflammatory and autoimmune diseases was highlighted.Notably,the recently developed RORγt inhibitors were summarized,with an emphasis on their optimization from lead compounds,efficacy,toxicity,mechanisms of action,and clinical trials.The limitations of current development in this area were also discussed to facilitate future research.

A GROWTH INHIBITOR SECRETED FROM CULTURED RABBIT SMOOTHMUSCLE CELLS IS DISTINCT FROM TGF-

Objective To ascertain whether the growth inhibitor in conditioned medium from cultured rabbit arterial cells is dlstinct rrom TGF-β. Methods Rabbit aortic smooth muscle cells were grown from explained segments or the aorta. Conditioned medium from cultured rabbit aortic smooth muscle cells and anti-TGF-β were employed in this study. Smooth muscle cell proliferation was measured by XTT detection(Boehringer Mannheim). Results Acidified conditioned medium from smooth muscle cells had significantly stronger effects or growth inhibition than controls,and anti-TGF-β did not affect the growth inhibitory effect of conditioned medium from cuitured rabbit arterial smooth muscle cells. Conclusion The growth innhibiting substance in conditioned medium from cultured rabbit aortic smooth muscle cells is distinct from

Role of TGF-<i>β</i>in breast cancer bone metastases

Breast cancer is the most prevalent cancer among females worldwide leading to approximately 350,000 deaths each year. It has long been known that cancers preferentially metastasize to particular organs, and bone metastases occur in ~70% of patients with advanced breast cancer. Breast cancer bone metastases are predominantly osteolytic and accompanied by increased fracture risk, pain, nerve compression and hypercalcemia, causing severe morbidity. In the bone matrix, transforming growth factor-β (TGF-β) is one of the most abundant growth factors, which is released in active form upon tumor-induced osteoclastic bone resorption. TGF-β, in turn, stimulates bone metastatic tumor cells to secrete factors that further drive osteolytic bone destruction adjacent to the tumor. Thus, TGF-β is a crucial factor responsible for driving the feed-forward vicious cycle of cancer growth in bone. Moreover, TGF-β activates epithelial-to-mesenchymal transition, increases tumor cell invasiveness and angiogenesis and induces immunosuppression. Blocking the TGF-β signaling pathway to interrupt this vicious cycle between breast cancer and bone offers a promising target for therapeutic intervention to decrease skeletal metastasis. This review will describe the role of TGF-β in breast cancer and bone metastasis, and pre-clinical and clinical data will be evaluated for the potential use of TGF-β inhibitors in clinical practice to treat breast cancer bone metastases.

3D-QSAR Studies on 4-([1,2,4]Triazolo[1,5-α]pyridin-6-yl)-5(3)-(6-methylpyridin-2-yl)imidazole Analogues as Potent Inhibitors of Transforming Growth Factor-β Type Ⅰ Receptor Kinase

The transforming growth factor-β （TGF-β） plays a crucial role in the beginning andprogression of fibrosis in various organ systems such as lung, heart, liver and kidney. TGF-fl type Ireceptor kinase （activin receptor-like kinase 5, ALK5） inhibitors might have potential activity forthe treatment of relevant diseases. In this paper, the three-dimensional quantitativestructure-activity relationship （3D-QSAR） including comparative molecular field analysis （CoMFA）and comparative molecular similarity indices analysis （CoMSIA） were used to analyze thestructural requirements based on a dataset of 123 4-（[1,2,4]Triazolo[1,5-a]pyridine-6-yl）-5（3）-（6-methylpyridin-2-yl）imidazole analogues which acted as ALK5 inhibitors. The obtainedCoMFA model （q2= 0.652, r2= 0.876, r2pred = 0.845） and CoMSIA model （q^2= 0.648, r^2= 0.884,r^2pred = 0.853） were robust and satisfactory. The predictive ability of the derived models wasvalidated using a test set of 28 compounds. Additionally, potentially important structural featuresrequired to enhance activity were also elucidated by the contour maps derived from CoMFA andCoMSIA models. The results will be helpful to guide drug design strategies aimed at obtainingpotent and selective ALK5 inhibitors.

TGF-beta1 Transgenic Mouse Model of Thoracic Irradiation: Modulation of MMP-2 and MMP-9 in the Lung Tissue

To investigate the effects of TGF-β1 on the two gelatinases （MMP-2 and MMP-9）, and their roles in lung remodeling after irradiation-induced lung injury. Expressions of TGF-β1 were measured with western blot, and expressions of MMP-2 and MMP-9 were analyzed with zymography in a TGF-β1 transgenic mouse model after thoracic irradiation with 12 Gy. We found expressions of TGF-β1 in the lung from the transgenic mice were three folds as compared to those from control mice. With densitometrical analysis, we found a significant decrease in MMP-9 activity in lung homogenates from the transgenic mice as compared with those from non-transgenic control mice 8 weeks after sham-irradiation （relative MMP-9 activity： C： 1. 000±0. 1091; TG： 0. 4772±0. 470 （n=8, P〈0.05）. But MMP-2 was constitutively expressed in the lung homogenates from the transgenic mice as compared to those from control mice 8 weeks after sham-irradiation （relative MMP-2 activity 8 weeks after sham-irradiation： C： 1. 000±0. 1556, TG： 1. 0075±0. 1472）. Eight weeks after thoracic irradiation with 12 Gy, we observed a significant increase of MMP-2 and MMP-9 activity in lung homogenates from both transgenic and normal mice. In TGF-β1 transgenic mice relative MMP-9 activity was increased to 1. 5321±0. 2217 folds 8 weeks after thoracic irradiation with 12 Gy as compared to those after sham-irradiation （1. 000±0. 2153）, and relative MMP-2 activity was increased to 1. 7142 ± 0. 4231 folds. Our results show that TGF-β1 itself down-regulates activity of MMP-9, thereby decreases ECM degradation in lungs of TGF-β1 transgenic mice. Also we find that ionizing irradiation upregulates both MMP-2 and MMP-9 activity. Over-expressions of MMP-9 and MMP-2 after lung irradiation are involved in the inflammatory response associated with radiation-induced lung injury, and maybe further in radiation-induced lung fibrosis.

Targeting Transforming Growth Factor-<i>β</i>(TGF-<i>β</i>) in Cancer and Non-Neoplastic Diseases

Transforming growth factor-β?(TGF-β) superfamily is a key player in the regulation of a wide variety of physiological processes from development to pathogenesis. Since the discovery of the prototypic member, TGF-β, almost three decades ago, there have been tremendous advances in our understanding of its complex biology. TGF-β?misregulation has been implicated in the pathogenesis of a variety of diseases, including cancer with a direct role in facilitating metastasis, fibrosis and inflammation. Consequently, TGF-β?is currently explored as a prognostic candidate biomarker of tumor invasiveness and metastasis;and it offers an attractive target for cancer therapy. Several anti-TGF-β?approaches, such as TGF-β?antibodies, antisense oligonucleotides and small molecules inhibitors of TGF-β?type 1 receptor kinase, have shown great promise in the preclinical studies. Here, we consider why the TGF-βsignaling pathway is a drug target, the potential clinical applications of TGF-β?inhibition, the issues arising with anti-TGF-β?therapy and how these might be adopted using personalized approaches with a special care for patient selection and timing of therapy so that we may bring forward all the potentials of targeting this pathway for therapeutic uses in both cancer, preferentially in combination therapy, and non-neoplastic diseases.

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.

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.

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.

Development of small-molecule viral inhibitors targeting various stages of the life cycle of emerging and re-emerging viruses

In recent years, unexpected outbreaks of infectious diseases caused by emerging and re-emerging viruses have become more frequent, which is possibly due to environmental changes. These outbreaks result in the loss of life and economic hardship. Vaccines and therapeutics should be developed for the prevention and treatment of infectious diseases. In this review, we summarize and discuss the latest progress in the development of small-molecule viral inhibitors against highly pathogenic coronaviruses, including severe acute respiratory syndrome coronavirus and Middle East respiratory syndrome coronavirus, Ebola virus, and Zika virus. These viruses can interfere with the specific steps of viral life cycle by blocking the binding between virus and host cells, disrupting viral endocytosis, disturbing membrane fusion, and interrupting viral RNA replication and translation, thereby demonstrating potent therapeutic effect against various emerging and re-emerging viruses. We also discuss some general strategies for developing small-molecule viral inhibitors.

STAT3 as a target for inducing apoptosis in solid and hematological tumors

Studies in the past few years have provided compelling evidence for the critical role of aberrant Signal Transducer and Activator of Transcription 3 （STAT3） in malignant transformation and tumorigenesis. Thus, it is now generally accepted that STAT3 is one of the critical players in human cancer formation and represents a valid target for novel anticancer drug design. This review focuses on aberrant STAT3 and its role in promoting tumor cell survival and sup- porting the malignant phenotype. A brief evaluation of the current strategies targeting STAT3 for the development of novel anticancer agents against human tumors harboring constitutively active STAT3 will also be presented.

Targeted therapies in epithelial ovarian cancer: Molecular mechanisms of action

Ovarian cancer is the leading cause of death in women with gynecological cancer. Most patients are diagnosed at an advanced stage and have a poor prognosis.Currently, surgical tumor debulking, followed by platinum- and taxane-based chemotherapy is the standard treatment for advanced ovarian cancer. However, these patients are at great risk of recurrence and emerging drug resistance. Therefore, novel treatment strategies are required to improve outcomes for women with advanced ovarian cancer. A variety of molecular targeted agents, the majority of which are monoclonal antibodies and small-molecule protein-kinase inhibitors, have been explored in the management of ovarian cancer. The targets of these agents include angiogenesis, the human epidermal growth factor receptor family, ubiquitinproteasome pathway, epigenetic modulators, poly(ADPribose) polymerase (PARP), and mammalian target of rapamycin (mTOR) signaling pathway, which are aberrant in tumor tissue. The antiangiogenic agent, bevacizumab, has been reported as the most effective targeted agent and should be included in the standard chemotherapeutic regimen for advanced ovarian cancer. PARP inhibitors, which are mainly used in breast and ovarian cancer susceptibility gene-mutated patients, and mTOR inhibitors are also attractive treatment strategies, either alone or combination with chemotherapy, for ovarian cancer. Understanding the tumor molecular biology and identification of predictive biomarkers are essential steps for selection of the best treatment strategies. This article reviews the molecular mechanisms of the most promising targeted agents that are under early phase clinical evaluation for ovarian cancer.

Sirtuin 5:a review of structure,known inhibitors and clues for developing new inhibitors

Sirtuins(SIRTs) are nicotinamide adenine dinucleotide(NAD^+)-dependent protein deacetylases,which regulate important biological processes ranging from apoptosis,age-associated pathophysiologies,adipocyte and muscle differentiation,and energy expenditure to gluconeogenesis.Very recently,sirtuin 5(SIRT5) has received considerable attention due to that it was found to have weak deacetylase activity but strong desuccinylase,demalonylase and deglutarylase activities,and it was also found to be associated with several human diseases such as cancer,Alzheimer's disease,and Parkinson's disease.In this review,we for the first time summarized the structure characteristics,known peptide and small-molecule inhibitors of SIRT5,extracted some clues from current available information and introduced some feasible,practical in silico methods,which might be useful in further efforts to develop new SIRT5 inhibitors.

SecA inhibitors:next generation antimicrobials

Health problems caused by bacterial infection have become a major public health concern in recent years due to the widespread emergence of drug-resistant bacterial strains.Therefore,the need for the development of new types of antimicrobial agents,especially those with a novel mechanism of action,is urgent.SecA,one of the key components of the secretion(Sec) pathway,is a new promising target for antimicrobial agent design.In recent years,promising leads targeting SecA have been identified and the feasibility of developing antimicrobial agents through the inhibition of SecA has been demonstrated.We hope this review will help stimulate more research in this area so that new antimicrobials can be obtained by targeting SecA.

Targeting autophagy-related protein kinases for potential therapeutic purpose

Autophagy,defined as a scavenging process of protein aggregates and damaged organelles mediated by lysosomes,plays a significant role in the quality control of macromolecules and organelles.Since protein kinases are integral to the autophagy process,it is critically important to understand the role of kinases in autophagic regulation.At present,intervention of autophagic processes by small-molecule modulators targeting specific kinases has becoming a reasonable and prevalent strategy for treating several varieties of human disease,especially cancer.In this review,we describe the role of some autophagy-related kinase targets and kinase-mediated phosphorylation mechanisms in autophagy regulation.We also summarize the small-molecule kinase inhibitors/activators of these targets,highlighting the opportunities of these new therapeutic agents.

Epithelial-mesenchymal transition in organ fibrosis development:current understanding and treatment strategies

Organ fibrosis is a process in which cellular homeostasis is disrupted and extracellular matrix is excessively deposited.Fibrosis can lead to vital organ failure and there are no effective treatments yet.Although epithelial-mesenchymal transition(EMT)may be one of the key cellular mechanisms,the underlying mechanisms of fibrosis remain largely unknown.EMT is a cell phenotypic process in which epithelial cells lose their cell-to-cell adhesion and polarization,after which they acquire mesenchymal features such as infiltration and migration ability.Upon injurious stimulation in different organs,EMT can be triggered by multiple signaling pathways and is also regulated by epigenetic mechanisms.This narrative review summarizes the current understanding of the underlying mechanisms of EMT in fibrogenesis and discusses potential strategies for attenuating EMT to prevent and/or inhibit fibrosis.Despite better understanding the role of EMT in fibrosis development,targeting EMT and beyond in developing therapeutics to tackle fibrosis is challenging but likely feasible.

Novel phthalimides regulating PD-1/PD-L1 interaction as potential immunotherapy agents

Programmed cell death 1(PD-1)/programmed cell death ligand 1(PD-L1)have emerged as one of the most promising immune checkpoint targets for cancer immunotherapy.Despite the inherent advantages of small-molecule inhibitors over antibodies,the discovery of small-molecule inhibitors has fallen behind that of antibody drugs.Based on docking studies between small molecule inhibitor and PD-L1 protein,changing the chemical linker of inhibitor from a flexible chain to an aromatic ring may improve its binding capacity to PD-L1 protein,which was not reported before.A series of novel phthalimide derivatives from structure-based rational design was synthesized.P39 was identified as the best inhibitor with promising activity,which not only inhibited PD-1/PD-L1 interaction(IC_(50)=8.9 nmol/L),but also enhanced killing efficacy of immune cells on cancer cells.Co-crystal data demonstrated that P39 induced the dimerization of PD-L1 proteins,thereby blocking the binding of PD-1/PD-L1.Moreover,P39 exhibited a favorable safety profile with a LD_(50)>5000 mg/kg and showed significant in vivo antitumor activity through promoting CD8^(+)T cell activation.All these data suggest that P39 acts as a promising small chemical inhibitor against the PD-1/PD-L1 axis and has the potential to improve the immunotherapy efficacy of T-cells.