ABSTRACT
Multiple sclerosis (MS) is a neuroinflammatory autoimmune disease and lacks effective therapeutic agents. Dysregulation of transcription mediated by bromodomain and extra-terminal domain (BET) proteins containing two different bromodomains (BD1 and BD2) is an important factor in multiple diseases, including MS. Herein, we identified a series of BD1-biased inhibitors, in which compound 16 showed nanomolar potency for BD1 (Kd = 230 nM) and a 60-fold selectivity for BRD4 BD1 over BD2. The co-crystal structure of BRD4 BD1 with 16 indicated that the hydrogen bond interaction of 16 with BD1-specific Asp145 is important for BD1 selectivity. 16 showed favorable brain distribution in mice and PK properties in rats. 16 was able to inhibit microglia activation and had significant therapeutic effects on EAE mice including improvement of spinal cord inflammatory conditions and demyelination protection. Overall, these results suggest that brain-permeable BD1 inhibitors have the potential to be further investigated as therapeutic agents for MS.
Subject(s)
Multiple Sclerosis , Transcription Factors , Rats , Mice , Animals , Transcription Factors/metabolism , Nuclear Proteins/metabolism , Multiple Sclerosis/drug therapy , Protein Domains , Brain/metabolism , Cell Cycle Proteins/metabolismABSTRACT
Janus kinases (JAKs) play a critical role in modulating the function and expression of inflammatory cytokines related to rheumatoid arthritis (RA). Herein, we report the design, synthesis, and structure-activity relationships (SARs) of a series of novel quinazoline derivatives as JAK inhibitors. Among these inhibitors, compound 11n showed high potency against JAKs (JAK1/JAK2/JAK3/TYK2, IC50 = 0.40, 0.83, 2.10, 1.95 nM), desirable metabolic characters, and excellent pharmacokinetic properties. In collagen-induced arthritis (CIA) models, compound 11n exhibited significant reduction in joint swelling with good safety, which could be served as a potential therapeutic candidate for the treatment of inflammatory diseases.
Subject(s)
Arthritis, Rheumatoid , Janus Kinase Inhibitors , Humans , Janus Kinase Inhibitors/pharmacology , Janus Kinase Inhibitors/therapeutic use , Quinazolines/pharmacology , Quinazolines/therapeutic use , Janus Kinases , Structure-Activity Relationship , Arthritis, Rheumatoid/drug therapy , Protein Kinase Inhibitors/pharmacology , Protein Kinase Inhibitors/therapeutic useABSTRACT
Neuropathic pain (NP) is an intolerable pain syndrome that arises from continuous inflammation and excitability after nerve injury. Only a few NP therapeutics are currently available, and all of them do not provide adequate pain relief. Herein, we report the discovery of a selective and potent inhibitor of the bromodomain and extra-terminal (BET) proteins for reducing neuroinflammation and excitability to treat NP. Starting with the screening hit 1 from an in-house compound library, iterative optimization resulted in the potent BET inhibitor DDO-8926 with a unique binding mode and a novel chemical structure. DDO-8926 exhibits excellent BET selectivity and favorable drug-like properties. In mice with spared nerve injury, DDO-8926 significantly alleviated mechanical hypersensitivity by inhibiting pro-inflammatory cytokine expression and reducing excitability. Collectively, these results implicate that DDO-8926 is a promising agent for the treatment of NP.
Subject(s)
Drug Discovery , Neuralgia , Mice , Animals , Drug Discovery/methods , Protein Domains , Cytokines , Pyridines/pharmacology , Pyridines/therapeutic use , Neuralgia/drug therapyABSTRACT
Overexpression of nectin cell adhesion protein 4 correlates with cancer progression and poor prognosis in many human malignancies. Enfortumab vedotin (EV) is the first nectin-4-targeting antibody-drug conjugate (ADC) approved by the FDA for the treatment of urothelial cancer. However, inadequate efficacy has limited progress in the treatment of other solid tumors with EV. Furthermore, ocular, pulmonary, and hematologic toxic side effects are common in nectin-4-targeted therapy, which frequently results in dose reduction and/or treatment termination. Thus, we designed a second generation nectin-4-specific drug, 9MW2821, based on interchain-disulfide drug conjugate technology. This novel drug contained a site specifically conjugated humanized antibody and the cytotoxic moiety monomethyl auristatin E. The homogenous drug-antibody ratio and novel linker chemistry of 9MW2821 increased the stability of conjugate in the systemic circulation, enabling highly efficient drug delivery and avoiding off-target toxicity. In preclinical evaluation, 9MW2821 exhibited nectin-4-specific cell binding, efficient internalization, bystander killing, and equivalent or superior antitumor activity compared with EV in both cell line-derived xenograft and patient-derived xenograft (PDX) models. In addition, 9MW2821 demonstrated a favorable safety profile; the highest nonseverely toxic dose in monkey toxicologic studies was 6 mg/kg, with milder adverse events compared with EV. Overall, 9MW2821 is a nectin-4-directed, investigational ADC based on innovative technology that endowed the drug with compelling preclinical antitumor activity and a favorable therapeutic index. The 9MW2821 ADC is being investigated in a phase I/II clinical trial (NCT05216965 and NCT05773937) in patients with advanced solid tumors.
Subject(s)
Immunoconjugates , Neoplasms , Humans , Immunoconjugates/pharmacology , Immunoconjugates/therapeutic use , Nectins , Xenograft Model Antitumor Assays , Neoplasms/drug therapy , Cell Adhesion Molecules , Cell Line, TumorABSTRACT
Estrogen-related receptor alpha (ERRα), a member of the nuclear receptor superfamily, is strongly expressed in breast cancer cells. Its overexpression is associated with poor prognosis in triple- negative Breast Cancer (TNBC). ERRα expression could be inhibited by the downregulation of upstream oncogenic growth factors mTOR, HER2, and PI3K. Low expression of ERRα could suppress the migration and angiogenesis of tumor cells by inhibiting the activity of its downstream signals VEGF and WNT11. Studies have confirmed that ERRα inverse agonists can inhibit ERRα expression to treat breast cancer. Inverse agonists of ERRα could disrupt the interactions of ERRα with its coactivators and inhibit tumor development. Existing ERRα inverse agonists have shown moderate efficacy in inhibiting the growth of breast cancer cells. Clinical inverse agonists of ERRα have not been found in the literature. This review focuses on the research progress and the structureactivity relationship of ERRα inverse agonists, providing guidance for the research and discovery of new anti-tumor compounds for TNBC.
Subject(s)
Triple Negative Breast Neoplasms , Humans , Triple Negative Breast Neoplasms/drug therapy , Triple Negative Breast Neoplasms/metabolism , Triple Negative Breast Neoplasms/pathology , Cell Line, Tumor , Drug Inverse Agonism , Chemistry, Pharmaceutical , Receptors, Estrogen/metabolism , Receptors, Estrogen/therapeutic use , ERRalpha Estrogen-Related ReceptorABSTRACT
The receptor tyrosine kinase AXL is an emerging driver of cancer recurrence, while its molecular mechanism remains unclear. In this study we investigated how AXL regulated the disease progression and poor prognosis in non-small cell lung cancer (NSCLC) and triple negative breast cancer (TNBC). We performed AXL transcriptome analysis from TCGA datasets, and found that AXL expression was significantly elevated in NSCLC and TNBC correlating with poor prognosis, epithelial-mesenchymal transition (EMT) and immune-tolerant tumor microenvironment (TME). Knockdown of AXL or treatment with two independent AXL antibodies (named anti-AXL and AXL02) all diminished cell migration and EMT in AXL-high expressing NSCLC and TNBC cell lines. In a mouse model of 4T1 TNBC, administration of anti-AXL antibody substantially inhibited lung metastases formation and growth, accompanied by reduced downstream signaling activation, EMT and proliferation index, as well as an increased apoptosis and activated anti-tumor immunity. We found that AXL was abundantly activated in tumor nodule-infiltrated M2-macrophages. A specific anti-AXL antibody blocked bone marrow-derived macrophage (BMDM) M2-polarization in vitro. Targeting of AXL in M2-macrophage in addition to tumor cell substantially suppressed CSF-1 production and eliminated M2-macrophage in TME, leading to a coordinated enhancement in both the innate and adaptive immunity reflecting M1-like macrophages, mature dendritic cells, cytotoxic T cells and B cells. We generated a novel and humanized AXL-ADC (AXL02-MMAE) employing a site-specific conjugation platform. AXL02-MMAE exerted potent cytotoxicity against a panel of AXL-high expressing tumor cell lines (IC50 < 0.1 nmol/L) and suppressed in vivo growth of multiple NSCLC and glioma tumors (a minimum efficacy dose<1 mg/kg). Compared to chemotherapy, AXL02-MMAE achieved a superior efficacy in regressing large sized tumors, eliminated AXL-H tumor cell-dependent M2-macrophage infiltration with a robust accumulation of inflammatory macrophages and mature dendritic cells. Our results support AXL-targeted therapy for treatment of advanced NSCLC and TNBC.
Subject(s)
Carcinoma, Non-Small-Cell Lung , Lung Neoplasms , Triple Negative Breast Neoplasms , Humans , Animals , Mice , Carcinoma, Non-Small-Cell Lung/drug therapy , Lung Neoplasms/pathology , Cell Proliferation , Epithelial-Mesenchymal Transition , Triple Negative Breast Neoplasms/drug therapy , Triple Negative Breast Neoplasms/pathology , Cell Line, Tumor , Antibodies/metabolism , Macrophages/metabolism , Tumor MicroenvironmentABSTRACT
The renin-angiotensin-aldosterone system (RAAS) plays a key role in the regulation of blood pressure. Renin, the first and rate-limiting enzyme of the RAAS, is an attractive target for the treatment of hypertension and cardiovascular/renal diseases. Therefore, various direct renin inhibitors (DRIs) have been researched over recent decades; however, most exhibited poor pharmacokinetics and oral bioavailability due to the peptidomimetic or nonpeptidomimetic structures with a molecular weight (MW) of >600, and only aliskiren is approved. This study introduces a novel class of DRIs comprised of a 2-carbamoyl morpholine scaffold. These compounds have a nonpeptidomimetic structure and a MW of <500. The representative compound 26 was highly potent despite not occupying S1'-S2' sites or the opened flap region used by other DRIs and exerted a significant antihypertensive efficacy via oral administration on double transgenic mice carrying both the human angiotensinogen and the human renin genes.
ABSTRACT
Renin is the rate-limiting enzyme in the renin-angiotensin-aldosterone system (RAAS) which regulates blood pressure and renal function and hence is an attractive target for the treatment of hypertension and cardiovascular/renal diseases. However, the development of direct renin inhibitors (DRIs) with favorable oral bioavailability has been a longstanding challenge for many years. This problem was thought to be because most of the reported DRIs were peptide-like structures or nonpeptide-like structures with a molecular weight (MW) of > 600. Therefore, we tried to find nonpeptidomimetic DRIs with a MW of < 500 and discovered the promising 2-carbamoyl morpholine derivative 4. In our efforts to improve the pharmacokinetic profile of 4 without a significant increase in the MW, we discovered compound 18 (SPH3127), which demonstrated higher bioavailability and a more potent antihypertensive effect in preclinical models than aliskiren and has completed a phase II clinical trial for essential hypertension.
Subject(s)
Hypertension , Renin , Amides/pharmacology , Amides/therapeutic use , Antihypertensive Agents/pharmacology , Antihypertensive Agents/therapeutic use , Fumarates/pharmacology , Fumarates/therapeutic use , Humans , Hypertension/drug therapy , Morpholines/pharmacology , Renin/pharmacology , Renin/therapeutic use , Renin-Angiotensin SystemABSTRACT
Idiopathic pulmonary fibrosis (IPF) is a chronic fatal lung disease with a median survival time of 3-5 years. Inaccurate diagnosis, limited clinical therapy and high mortality together indicate that the development of effective therapeutics for IPF is an urgent need. In recent years, it was reported that DDRs are potential targets in anti-fibrosis treatment. Based on previous work we carried out further structure modifications and led to a more selective inhibitor 47 by averting some fibrosis-unrelated kinases, such as RET, AXL and ALK. Extensive profiling of compound 47 has demonstrated that it has potent DDR1/2 inhibitory activities, low toxicity, good pharmacokinetic properties and reliable in vivo anti-fibrosis efficacy. Therefore, we confirmed that discoidin domain receptors are promising drug targets for IPF, and compound 47 would be a promising candidate for further drug development.
ABSTRACT
Oestrogen related receptor α participated in the regulation of oxidative metabolism and mitochondrial biogenesis, and was overexpressed in many cancers including triple-negative breast cancer. A set of new ERRα inverse agonists based on p-nitrobenzenesulfonamide template were discovered and compound 11 with high potent activity (IC50 = 0.80 µM) could significantly inhibit the transcription of ERRα-regulated target genes. By regulating the downstream signalling pathway, compound 11 could suppress the migration and invasion of the ER-negative MDA-MB-231 cell line. Furthermore, compound 11 demonstrated a significant growth suppression of breast cancer xenograft tumours in vivo (inhibition rate 23.58%). The docking results showed that compound 11 could form hydrogen bonds with Glu331 and Arg372 in addition to its hydrophobic interaction with ligand-binding domain. Our data implied that compound 11 represented a novel and effective ERRα inverse agonist, which had broad application prospects in the treatment of triple-negative breast cancer.
Subject(s)
Antineoplastic Agents/pharmacology , Drug Discovery , Nitrobenzenes/pharmacology , Receptors, Estrogen/metabolism , Sulfonamides/pharmacology , Triple Negative Breast Neoplasms/drug therapy , Antineoplastic Agents/chemical synthesis , Antineoplastic Agents/chemistry , Cell Line, Tumor , Cell Proliferation/drug effects , Dose-Response Relationship, Drug , Drug Screening Assays, Antitumor , Female , Humans , Molecular Docking Simulation , Molecular Structure , Nitrobenzenes/chemical synthesis , Nitrobenzenes/chemistry , Structure-Activity Relationship , Sulfonamides/chemical synthesis , Sulfonamides/chemistry , Triple Negative Breast Neoplasms/metabolism , Triple Negative Breast Neoplasms/pathology , ERRalpha Estrogen-Related ReceptorABSTRACT
Aim: CDK4 is a promising target for breast cancer therapy. This study aimed to explore the structure-activity relationship of CDK4 inhibitor abemaciclib analogs and design potent CDK4 inhibitors for breast cancer treatment. Methods & results: A faithful 3D quantitative structure-activity relationship model was established by molecular docking, comparative molecular field analysis and comparative molecular similarity index analysis based on 56 abemaciclib analogs. Molecular dynamics simulation studies revealed the key residues of the interaction between CDK4 and inhibitors. Four novel inhibitors with satisfactory predicted binding affinity to CDK4 were designed. Conclusion: The 3D quantitative structure-activity relationship and molecular dynamics simulation studies provide valuable insight into the development of novel CDK4 inhibitors.
Subject(s)
Cyclin-Dependent Kinase 4/antagonists & inhibitors , Protein Kinase Inhibitors/pharmacology , Cyclin-Dependent Kinase 4/metabolism , Humans , Models, Molecular , Molecular Structure , Protein Kinase Inhibitors/chemistry , Quantitative Structure-Activity RelationshipABSTRACT
Estrogen-related receptor α (ERRα), which is overexpressed in a variety of cancers has been considered as an effective target for anticancer therapy. ERRα inverse agonists have been proven to effectively inhibit the migration and invasion of cancer cells. As few crystalline complexes have been reported, molecular dynamics (MD) simulations were carried out in this study to deepen the understanding of the interaction mechanism between inverse agonists and ERRα. The binding free energy was analyzed by the MM-GBSA method. The results show that the total binding free energy was positively correlated with the biological activity of an inverse agonist. The interaction of the inverse agonist with the hydrophobic interlayer composed of Phe328 and Phe495 had an important impact on the biological activity of inverse agonists, which was confirmed by the decomposition of energy on residues. As Glu331 flipped and formed a hydrogen bond with Arg372 in the MD simulation process, the formation of hydrogen bond interaction with Glu331 was not a necessary condition for the compound to act as an inverse agonist. These rules provide guidance for the design of new inverse agonists.
Subject(s)
Drug Inverse Agonism , Receptors, Estrogen/antagonists & inhibitors , Molecular Dynamics Simulation , ERRalpha Estrogen-Related ReceptorABSTRACT
G-quadruplexes (G4s) are DNA or RNA structures formed by guanine-rich repeating sequences. Recently, G4s have become a highly attractive therapeutic target for BRCA-deficient cancers. Here, we show that a substituted quinolone amide compound, MTR-106, stabilizes DNA G-quadruplexes in vitro. MTR-106 displayed significant antiproliferative activity in homologous recombination repair (HR)-deficient and PARP inhibitor (PARPi)-resistant cancer cells. Moreover, MTR-106 increased DNA damage and promoted cell cycle arrest and apoptosis to inhibit cell growth. Importantly, its oral and i.v. administration significantly impaired tumor growth in BRCA-deficient xenograft mouse models. However, MTR-106 showed modest activity against talazoparib-resistant xenograft models. In rats, the drug rapidly distributes to tissues within 5 min, and its average concentrations were 12-fold higher in the tissues than in the plasma. Overall, we identified MTR-106 as a novel G-quadruplex stabilizer with high tissue distribution, and it may serve as a potential anticancer agent.
Subject(s)
Antineoplastic Agents/pharmacology , BRCA1 Protein/biosynthesis , BRCA2 Protein/biosynthesis , G-Quadruplexes/drug effects , Animals , Antineoplastic Agents/pharmacokinetics , Cell Line, Tumor , Cell Survival/drug effects , DNA Repair/drug effects , Drug Resistance, Neoplasm/drug effects , Drug Resistance, Neoplasm/physiology , Humans , Male , Mice , Mice, Nude , Neoplasms/pathology , Phthalazines/pharmacology , Poly(ADP-ribose) Polymerase Inhibitors/pharmacology , Rats , Rats, Sprague-Dawley , Xenograft Model Antitumor AssaysABSTRACT
The Bromodomain and Extra-terminal domain (BET) proteins are promising targets in treating cancers. Although BET inhibitors have been in clinical trials, they are limited by lacking of suitable biomarkers to indicate drug responses in different cancers. Here we identify DHRS2, ETV4 and NOTUM as potential biomarkers to indicate drug resistance in liver cancer cells of a recently discovered BET inhibitor, Hjp-6-171. Furthermore, we confirm that reactivation of WNT pathway, the target of NOTUM, contributes to the drug sensitivity restoration in Hjp-6-171 resistant cells. Specially, combinations of Hjp-6-171 and a GSK3ß inhibitor CHIR-98014 show remarkable therapeutic effects in vitro and in vivo. Integrating RNA-seq and ChIP-seq data, we reveal the expression signature of ß-catenin regulated genes is contrary in sensitive cells to that in resistant cells. We propose WNT signaling molecules such as ß-catenin and ETV4 to be candidate biomarkers to indicate BET inhibitor responses in liver cancer patients.
Subject(s)
Liver Neoplasms , Wnt Signaling Pathway , Carbonyl Reductase (NADPH)/genetics , Carbonyl Reductase (NADPH)/metabolism , Cell Line, Tumor , Cell Proliferation/genetics , Gene Expression Regulation, Neoplastic , Humans , Liver Neoplasms/drug therapy , Liver Neoplasms/genetics , Wnt Signaling Pathway/genetics , beta Catenin/genetics , beta Catenin/metabolismABSTRACT
WD40 is a ubiquitous domain presented in at least 361 human proteins and acts as scaffold to form protein complexes. Among them, WDR5 protein is an important mediator in several protein complexes to exert its functions in histone modification and chromatin remodeling. Therefore, it was considered as a promising epigenetic target involving in anti-cancer drug development. In view of the protein-protein interaction nature of WDR5, we initialized a campaign to discover new peptide-mimic inhibitors of WDR5. In current study, we utilized the phage display technique and screened with a disulfide-based cyclic peptide phage library. Five rounds of biopanning were performed and isolated clones were sequenced. By analyzing the sequences, total five peptides were synthesized for binding assay. The four peptides are shown to have the moderate binding affinity. Finally, the detailed binding interactions were revealed by solving a WDR5-peptide cocrystal structure.
Subject(s)
Drug Discovery , Intracellular Signaling Peptides and Proteins/antagonists & inhibitors , Peptide Library , Peptides, Cyclic/pharmacology , Humans , Intracellular Signaling Peptides and Proteins/metabolism , Ligands , Peptides, Cyclic/chemical synthesis , Peptides, Cyclic/chemistry , Protein BindingABSTRACT
Although tyrosine kinase inhibitor therapy and immunotherapy have significantly improved lung cancer management, many patients do not benefit or become resistant to treatment, highlighting the need for novel treatments. We found elevated CD73 expression to be prevalent in non-small cell lung cancer (NSCLC) including those harboring the RAS- or RTK (EGFR, EML4-ALK) oncogenes. CD73 expression is enriched closely with the transcriptome signature of epithelial-mesenchymal transition and the immune-tolerant tumor microenvironment, which are increasingly relevant for disease progression and therapy resistance. We developed two novel series of CD73 antibody, Ab001/Ab002 and humanized version Hu001/Hu002, which demonstrated high CD73 binding affinity, potent enzyme inhibition, and efficiently protected effector T lymphocyte function from adenosine/cancer-imposed toxicity. Hu001/Hu002 inhibited growth of RAS-mutant NSCLC tumors in mice via enhanced antibody-dependent cell-mediated cytotoxicity and multifaceted remodeling of the tumor immune environment, reflecting diminished levels of tumor-associated macrophages, myeloid-derived suppressor cells, and tumor vasculature. A novel MMAE-conjugated CD73-ADC (Hu001-MMAE) elicited potent cytotoxicity against CD73-high expressing tumor cells (IC50<0.1 nmol/L) and suppressed in vivo growth of multiple NSCLC and glioma tumors, including the RAS-mutant models [minimum effective dose <1 mg/kg]. Treatment with CD73-ADC triggered a robust intratumoral accumulation of proinflammatory macrophages and activated dendritic cells (DC), which were not observed with naked CD73 antibody or standard chemotherapy. Studies with human PBMC-derived systems confirmed CD73-ADC as fully functional in protecting effector T cells and stimulating DCs thus providing dual benefits in killing CD73-high tumors and improving cancer immunity response. These results warrant clinical investigation of CD73-targeted antibody and ADC for treating advanced lung cancer.
Subject(s)
5'-Nucleotidase/antagonists & inhibitors , Antineoplastic Agents, Immunological/pharmacology , Immunoconjugates/pharmacology , 5'-Nucleotidase/genetics , 5'-Nucleotidase/metabolism , Animals , Cell Line, Tumor , Cell Proliferation/drug effects , Disease Models, Animal , Dose-Response Relationship, Drug , Epithelial-Mesenchymal Transition/drug effects , Epithelial-Mesenchymal Transition/genetics , GPI-Linked Proteins/antagonists & inhibitors , GPI-Linked Proteins/genetics , GPI-Linked Proteins/metabolism , Gene Knockdown Techniques , Humans , Lung Neoplasms , Mice , Molecular Targeted Therapy , Neovascularization, Pathologic/genetics , Receptors, IgG/metabolism , T-Lymphocytes , Treatment Outcome , Tumor Microenvironment/drug effects , Xenograft Model Antitumor AssaysABSTRACT
Cancer exhibits diverse heterogeneity with a complicated molecular basis that usually harbors genetic and epigenetic abnormality, which poses a big challenge for single-target agents. In the current work, we proposed a hybrid strategy by incorporating pharmacophores that bind to the acetylated lysine binding pocket of BET proteins with a typical kinase hinge binder to generate novel polypharmacological inhibitors of BET and kinases. Through elaborating the core structure of 6-(pyrimidin-2-ylamino)-3,4-dihydroquinoxalin-2(1H)-one, we demonstrated that this rational design can produce high potent inhibitors of CDK9 and BET proteins. In this series, compound 40 was identified as the potential lead compound with balanced activities of BRD4 (IC50 = 12.7 nM) and CDK9 (IC50 = 22.4 nM), as well as good antiproliferative activities on a small cancer cell panel. Together, the current study provided a new method for the discovery of bromodomain and kinase dual inhibitors rather than only being discovered by serendipity.
Subject(s)
Drug Design , Protein Kinase Inhibitors/chemistry , Protein Kinase Inhibitors/pharmacology , Quinoxalines/chemistry , Quinoxalines/pharmacology , Animals , Cell Cycle Proteins/antagonists & inhibitors , Cell Line, Tumor , Cell Proliferation/drug effects , Cyclin-Dependent Kinase 9/antagonists & inhibitors , Drug Discovery , Humans , Mice , Models, Molecular , Protein Domains , Protein Kinase Inhibitors/pharmacokinetics , Quinoxalines/pharmacokinetics , Structure-Activity Relationship , Transcription Factors/antagonists & inhibitorsABSTRACT
An amendment to this paper has been published and can be accessed via a link at the top of the paper.
ABSTRACT
The bromodomain and extra-terminal domain (BET) family of proteins, especially bromodomain-containing protein 4 (BRD4), has emerged as exciting anti-tumor targets due to their important roles in epigenetic regulation. Therefore, the discovery of BET inhibitors with promising anti-tumor efficacy will provide a novel approach to epigenetic anticancer therapy. Recently, we discovered the new BET inhibitor compound 171, which is derived from a polo-like kinase 1 (PLK1)-BRD4 dual inhibitor based on our previous research. Compound 171 was found to maintain BET inhibition ability without PLK1 inhibition, and there was no selectivity among BET family members. The in vitro and in vivo results both indicated that the overall anti-tumor activity of compound 171 was improved compared with the (+)-JQ-1 or OTX-015 BET inhibitors. Furthermore, we found that compound 171 could regulate the expression of cell cycle-regulating proteins including c-Myc and p21 and induce cell cycle arrest in the G0/G1 phase. However, compound 171 only has a quite limited effect on apoptosis, in considering that apoptosis was only observed at doses greater than 50 µM. To determine the mechanisms underlying cell death, proliferation activity assay was conducted. The results showed that compound 171 induced clear anti-proliferative effects at doses that no obvious apoptosis was induced, which indicated that the cell cycle arresting effect contributed mostly to its anti-tumor activity. The result of this study revealed the anti-tumor mechanism of compound 171, and laid a foundation for the combination therapy in clinical practice, if compound 171 or its series compounds become drug candidates in the future.