ABSTRACT
As an obstinate cancer pancreatic cancer (PC) poses a major challenge due to limited treatment options which include resection surgery, radiation therapy, and gemcitabine-based chemotherapy. In cancer cells, protein kinase C ßI (PKCßI) participates in diverse cellular processes, including cell proliferation, invasion, and apoptotic pathways. In the present study, we created a scaffold to develop PKCßI inhibitors using evodiamine-based synthetic molecules. Among the candidate inhibitors, Evo312 exhibited the highest antiproliferative efficacy against PC cells, PANC-1, and acquired gemcitabine-resistant PC cells, PANC-GR. Additionally, Evo312 robustly inhibited PKCßI activity. Mechanistically, Evo312 effectively suppressed the upregulation of PKCßI protein expression, leading to the induction of cell cycle arrest and apoptosis in PANC-GR cells. Furthermore, Evo312 exerted an antitumor activity in a PANC-GR cell-implanted xenograft mouse model. These findings position Evo312 as a promising lead compound for overcoming gemcitabine resistance in PC through novel mechanisms.
ABSTRACT
Molecular glues are proximity-inducing small molecules that have emerged as an attractive therapeutic approach. However, developing molecular glues remains challenging, requiring innovative mechanistic strategies to stabilize neoprotein interfaces and expedite discovery. Here we unveil a trans-labeling covalent molecular glue mechanism, termed 'template-assisted covalent modification'. We identified a new series of BRD4 molecular glue degraders that recruit CUL4DCAF16 ligase to the second bromodomain of BRD4 (BRD4BD2). Through comprehensive biochemical, structural and mutagenesis analyses, we elucidated how pre-existing structural complementarity between DCAF16 and BRD4BD2 serves as a template to optimally orient the degrader for covalent modification of DCAF16Cys58. This process stabilizes the formation of BRD4-degrader-DCAF16 ternary complex and facilitates BRD4 degradation. Supporting generalizability, we found that a subset of degraders also induces GAK-BRD4BD2 interaction through trans-labeling of GAK. Together, our work establishes 'template-assisted covalent modification' as a mechanism for covalent molecular glues, which opens a new path to proximity-driven pharmacology.
ABSTRACT
Cyclin-dependent kinase 7, along with cyclin H and MAT1, forms the CDK-activating complex (CAK), which directs cell cycle progression via T-loop phosphorylation of cell cycle CDKs. Pharmacological inhibition of CDK7 leads to selective anti-cancer effects in cellular and in vivo models, motivating several ongoing clinical investigations of this target. Current CDK7 inhibitors are either reversible or covalent inhibitors of its catalytic activity. We hypothesized that small molecule targeted protein degradation (TPD) might result in differentiated pharmacology due to the loss of scaffolding functions. Here, we report the design and characterization of a potent CDK7 degrader that is comprised of an ATP-competitive CDK7 binder linked to a CRL2VHL recruiter. JWZ-5-13 effectively degrades CDK7 in multiple cancer cells and leads to a potent inhibition of cell proliferation. Additionally, compound JWZ-5-13 displayed bioavailability in a pharmacokinetic study conducted in mice. Therefore, JWZ-5-13 is a useful chemical probe to investigate the pharmacological consequences of CDK7 degradation.
Subject(s)
Cell Proliferation , Cyclin-Dependent Kinases , Protein Kinase Inhibitors , Humans , Animals , Protein Kinase Inhibitors/pharmacology , Protein Kinase Inhibitors/chemistry , Protein Kinase Inhibitors/chemical synthesis , Cell Proliferation/drug effects , Mice , Cyclin-Dependent Kinases/antagonists & inhibitors , Cyclin-Dependent Kinases/metabolism , Structure-Activity Relationship , Molecular Structure , Small Molecule Libraries/chemistry , Small Molecule Libraries/pharmacology , Small Molecule Libraries/chemical synthesis , Drug Discovery , Antineoplastic Agents/pharmacology , Antineoplastic Agents/chemistry , Antineoplastic Agents/chemical synthesis , Dose-Response Relationship, Drug , Cyclin-Dependent Kinase-Activating Kinase , Proteolysis/drug effects , Cell Line, Tumor , Drug Screening Assays, AntitumorABSTRACT
Small molecules promoting protein-protein interactions produce a range of therapeutic outcomes. Molecular glue degraders exemplify this concept due to their compact drug-like structures and ability to engage targets without reliance on existing cognate ligands. While Cereblon molecular glue degraders containing glutarimide scaffolds have been approved for treatment of multiple myeloma and acute myeloid leukemia, the design of new therapeutically relevant monovalent degraders remains challenging. We report here an approach to glutarimide-containing molecular glue synthesis using multicomponent reactions as a central modular core-forming step. Screening the resulting library identified HRZ-01 derivatives that target casein kinase 1 alpha (CK1α) and Wee-like protein kinase (WEE1). Further medicinal chemistry efforts led to identification of selective monovalent WEE1 degraders that provide a potential starting point for the eventual development of a selective chemical degrader probe. The structure of the hit WEE1 degrader complex with CRBN-DDB1 and WEE1 provides a model of the protein-protein interface and a rationale for the observed kinase selectivity. Our findings suggest that modular synthetic routes combined with in-depth structural characterization give access to selective molecular glue degraders and expansion of the CRBN-degradable proteome.
ABSTRACT
Small molecules that can induce protein degradation by inducing proximity between a desired target and an E3 ligase have the potential to greatly expand the number of proteins that can be manipulated pharmacologically. Current strategies for targeted protein degradation are mostly limited in their target scope to proteins with preexisting ligands. Alternate modalities such as molecular glues, as exemplified by the glutarimide class of ligands for the CUL4CRBN ligase, have been mostly discovered serendipitously. We recently reported a trans-labelling covalent glue mechanism which we named 'Template-assisted covalent modification', where an electrophile decorated small molecule binder of BRD4 was effectively delivered to a cysteine residue on an E3 ligase DCAF16 as a consequence of a BRD4-DCAF16 protein-protein interaction. Herein, we report our medicinal chemistry efforts to evaluate how various electrophilic modifications to the BRD4 binder, JQ1, affect DCAF16 trans-labeling and subsequent BRD4 degradation efficiency. We discovered a decent correlation between the ability of the electrophilic small molecule to induce ternary complex formation between BRD4 and DCAF16 with its ability to induce BRD4 degradation. Moreover, we show that a more solvent-exposed warhead presentation is optimal for DCAF16 recruitment and subsequent BRD4 degradation. Unlike the sensitivity of CUL4CRBN glue degraders to chemical modifications, the diversity of covalent attachments in this class of BRD4 glue degraders suggests a high tolerance and tunability for the BRD4-DCAF16 interaction. This offers a potential new avenue for a rational design of covalent glue degraders by introducing covalent warheads to known binders.
ABSTRACT
Targeted protein degradation relies on small molecules that induce new protein-protein interactions between targets and the cellular protein degradation machinery. Most of these small molecules feature specific ligands for ubiquitin ligases. Recently, the attachment of cysteine-reactive chemical groups to pre-existing small molecule inhibitors has been shown to drive specific target degradation. We demonstrate here that different cysteine-reactive groups can specify target degradation via distinct ubiquitin ligases. By focusing on the bromodomain ligand JQ1, we identify cysteine-reactive functional groups that drive BRD4 degradation by either DCAF16 or DCAF11. Unlike proteolysis-targeting chimeric molecules (PROTACs), the new compounds use a single small molecule ligand with a well-positioned cysteine-reactive group to induce protein degradation. The finding that nearly identical compounds can engage multiple ubiquitination pathways suggests that targeting cellular pathways that search for and eliminate chemically reactive proteins is a feasible avenue for converting existing small molecule drugs into protein degrader molecules.
ABSTRACT
Chemical probes are essential tools for understanding biological systems and for credentialing potential biomedical targets. Programmed cell death 2 (PDCD2) is a member of the B-cell lymphoma 2 (Bcl-2) family of proteins, which are critical regulators of apoptosis. Here we report the discovery and characterization of 10 e, a first-in-class small molecule degrader of PDCD2. We discovered this PDCD2 degrader by serendipity using a chemical proteomics approach, in contrast to the conventional approach for making bivalent degraders starting from a known binding ligand targeting the protein of interest. Using 10 e as a pharmacological probe, we demonstrate that PDCD2 functions as a critical regulator of cell growth by modulating the progression of the cell cycle in T lymphoblasts. Our work provides a useful pharmacological probe for investigating PDCD2 function and highlights the use of chemical proteomics to discover selective small molecule degraders of unanticipated targets.
Subject(s)
Apoptosis Regulatory Proteins , Lymphoma, B-Cell , Humans , Apoptosis Regulatory Proteins/metabolism , Proteomics , Apoptosis , Cell ProliferationABSTRACT
Based on hA2AAR structures, a hydrophobic C8-heteroaromatic ring in 5'-truncated adenosine analogues occupies the subpocket tightly, converting hA2AAR agonists into antagonists while maintaining affinity toward hA3AR. The final compounds of 2,8-disubstituted-N6-substituted 4'-thionucleosides, or 4'-oxo, were synthesized from d-mannose and d-erythrono-1,4-lactone, respectively, using a Pd-catalyst-controlled regioselective cross-coupling reaction. All tested compounds completely antagonized hA2AAR, including 5d with the highest affinity (Ki,A2A = 7.7 ± 0.5 nM). The hA2AAR-5d X-ray structure revealed that C8-heteroaromatic rings prevented receptor activation-associated conformational changes. However, the C8-substituted compounds still antagonized hA3AR. Structural SAR features and docking studies supported different binding modes at A2AAR and A3AR, elucidating pharmacophores for receptor activation and selectivity. Favorable pharmacokinetics were demonstrated, in which 5d displayed high oral absorption, moderate half-life, and bioavailability. Also, 5d significantly improved the antitumor effect of anti-PD-L1 in vivo. Overall, this study suggests that the novel dual A2AAR/A3AR nucleoside antagonists would be promising drug candidates for immune-oncology.
Subject(s)
Adenosine , Neoplasms , Humans , Adenosine/pharmacology , Androgen Receptor Antagonists , Immunotherapy , Purinergic P1 Receptor Antagonists , Structure-Activity Relationship , Thionucleosides/chemistry , Thionucleosides/pharmacologyABSTRACT
A targeted and logical discovery method was devised for natural products containing piperazic acid (Piz), which is biosynthesized from ornithine by l-ornithine N-hydroxylase (KtzI) and N-N bond formation enzyme (KtzT). Genomic signature-based screening of a bacterial DNA library (2020 strains) using polymerase chain reaction (PCR) primers targeting ktzT identified 62 strains (3.1%). The PCR amplicons of KtzT-encoding genes were phylogenetically analyzed to classify the 23 clades into two monophyletic groups, I and II. Cultivating hit strains in media supplemented with 15NH4Cl and applying 1H-15N heteronuclear multiple bond correlation (HMBC) along with 1H-15N heteronuclear single quantum coherence (HSQC) and 1H-15N HSQC-total correlation spectroscopy (HSQC-TOCSY) NMR experiments detected the spectroscopic signatures of Piz and modified Piz. Chemical investigation of the hit strains prioritized by genomic and spectroscopic signatures led to the identification of a new azinothricin congener, polyoxyperuin B seco acid (1), previously reported chloptosin (2) in group I, depsidomycin D (3) incorporating two dehydropiperazic acids (Dpz), and lenziamides A and B (4 and 5), structurally novel 31-membered cyclic decapeptides in group II. By consolidating the phylogenetic and chemical analyses, clade-structure relationships were elucidated for 19 of the 23 clades. Lenziamide A (4) inhibited STAT3 activation and induced G2/M cell cycle arrest, apoptotic cell death, and tumor growth suppression in human colorectal cancer cells. Moreover, lenziamide A (4) resensitized 5-fluorouracil (5-FU) activity in both in vitro cell cultures and the in vivo 5-FU-resistant tumor xenograft mouse model. This work demonstrates that the genomic and spectroscopic signature-based searches provide an efficient and general strategy for new bioactive natural products containing specific structural motifs.
Subject(s)
Biological Products , Genomics , Humans , Animals , Mice , Phylogeny , Spectrum Analysis , Biological Products/pharmacologyABSTRACT
Herein, atropisomeric 8-aryltetrahydroisoquinolines have been synthesized and biologically evaluated. Based on our structure-activity relationship study, a highly bioactive racemic compound has been produced, and it exhibited high antiproliferative activities against various cancer cell lines, including docetaxel-resistant breast cancer cell lines. Each enantiomer can be synthesized in an enantioselective manner by employing the chiral phosphoric acid-catalyzed atroposelective Pictet-Spengler cyclization. An axially (R)-configured enantiomer showed a higher biological activity compared with the axially (S)-configured enantiomer. Further biological studies suggested that the (R)-enantiomer overcomes docetaxel resistance via the downregulation of signal transducer and activator of transcription 3 activation and consequently induces cellular apoptosis in docetaxel-resistant triple-negative breast cancer cell lines.
Subject(s)
Tetrahydroisoquinolines , Triple Negative Breast Neoplasms , Humans , Docetaxel/pharmacology , Triple Negative Breast Neoplasms/drug therapy , Triple Negative Breast Neoplasms/metabolism , Apoptosis , Cell Line, TumorABSTRACT
Metastatic triple-negative breast cancer (mTNBC) is a fatal type of breast cancer (BC), and signal transducer and activator of transcription 3 (STAT3) has emerged as an effective target for mTNBC. In the present study, compound MC0704 was found to be a novel synthetic STAT3 pathway inhibitor, and its potential antitumor activity was demonstrated using in vitro and in vivo models in docetaxel-resistant TNBC cells. Based on marinacarboline (MC), a series ß-carboline derivatives were synthesized and investigated for their antitumor activities against docetaxel-resistant MDA-MB-231 (MDA-MB-231-DTR) cells. Combining antiproliferation and STAT3 inhibitory activities, MC0704 was selected as the most promising ß-carboline compound. MC0704 effectively impeded the metastatic potential of MDA-MB-231-DTR cells in vitro, and the combination of MC0704 and docetaxel exhibited potent antitumor activities in a xenograft mouse model. These findings suggested that MC0704 can be a lead candidate as a target therapeutic agent for TNBC patients with docetaxel resistance.
Subject(s)
Antineoplastic Agents , Triple Negative Breast Neoplasms , Humans , Animals , Mice , Docetaxel/therapeutic use , Triple Negative Breast Neoplasms/drug therapy , STAT3 Transcription Factor/metabolism , Apoptosis , Xenograft Model Antitumor Assays , Cell Line, Tumor , Cell Proliferation , Antineoplastic Agents/pharmacologyABSTRACT
Although gemcitabine-based chemotherapy is common and effective for pancreatic cancer (PC), acquired drug resistance is one of the major reasons for treatment failure. Therefore, a novel therapeutic approach for gemcitabine-resistant PC is required. Nuclear factor erythroid 2-related factor 2 (Nrf2) is an oxidative stress-responsive transcription factor regulating antioxidant responses and plays a crucial role in chemoresistance. In the present study, the antitumor activity of periplocin, a natural cardiac glycoside, was evaluated in an established gemcitabine-resistant PC cell line (PANC-GR). Nrf2 was overexpressed in gemcitabine-resistant cells, and Nrf2 knockdown recovered gemcitabine sensitivity in PANC-GR cells. The antiproliferative activity of periplocin was highly associated with Nrf2 downregulation and Nrf2-mediated signaling pathways in PANC-GR cells. Periplocin also increased reactive oxygen species production inducing G0/G1 cell cycle arrest and apoptosis in PANC-GR cells. Periplocin and gemcitabine combined significantly inhibited tumor growth in a PANC-GR cells-implanted xenograft mouse model via Nrf2 downregulation. Overall, these findings suggest that periplocin might be a novel therapeutic agent against gemcitabine resistance, as it could recover sensitivity to gemcitabine by regulating Nrf2-mediated signaling pathways in gemcitabine-resistant PC cells.
Subject(s)
Gemcitabine , Pancreatic Neoplasms , Humans , Mice , Animals , Deoxycytidine/pharmacology , Deoxycytidine/therapeutic use , Drug Resistance, Neoplasm , Cell Line, Tumor , Pancreatic Neoplasms/pathology , Signal Transduction , Apoptosis , Xenograft Model Antitumor Assays , Pancreatic NeoplasmsABSTRACT
Piceamycin (1), a macrocyclic lactam isolated from the silkworm's gut (Streptomyces sp. SD53 strain), reportedly possesses antibacterial activity. However, the potential anticancer activity and molecular processes underlying 1 have yet to be reported. Colorectal cancer (CRC) is high-risk cancer and accounts for 10% of all cancer cases worldwide. The high prevalence of resistance to radiation or chemotherapy means that patients with advanced CRC have a poor prognosis, with high recurrence and metastasis potential. Therefore, the present study investigated the antitumor effect and underlying mechanisms of 1 in CRC cells. The growth-inhibiting effect of 1 in CRC cells was correlated with the upregulation of a tumor suppressor, N-myc downstream-regulated gene 1 (NDRG1). Additionally, 1 induced G0/G1 cell cycle arrest and apoptosis and inhibited the migration of CRC cells. Notably, 1 disrupted the interaction between NDRG1 and c-Myc in CRC cells. In a mouse model with HCT116-implanted xenografts, the antitumor activity of 1 was confirmed by NDRG1 modulation. Overall, these findings show that 1 is a potential candidate for CRC treatment through regulation of NDGR1-mediated functionality.
Subject(s)
Cell Cycle Proteins , Colorectal Neoplasms , Animals , Mice , Humans , Lactams, Macrocyclic , Up-Regulation , Intracellular Signaling Peptides and Proteins/genetics , Intracellular Signaling Peptides and Proteins/metabolism , Colorectal Neoplasms/drug therapy , Colorectal Neoplasms/metabolism , Cell Proliferation , Cell Line, TumorABSTRACT
A genomic and spectroscopic signature-based search revealed a cycloaromatized enediyne, jejucarboside A (1), from a marine actinomycete strain. The structure of 1 was determined as a new cyclopenta[a]indene glycoside bearing carbonate functionality by nuclear magnetic resonance, high-resolution mass spectrometry (MS), MS/MS, infrared spectroscopy, and a modified Mosher's method. An iterative enediyne synthase pathway has been proposed for the putative biosynthesis of 1 by genomic analysis. Jejucarboside A exhibited cytotoxicity against the HCT116 colon carcinoma cells.
Subject(s)
Actinobacteria , Indenes , Actinobacteria/chemistry , Enediynes/chemistry , Glycosides/chemistry , Indenes/chemistry , Molecular Structure , Tandem Mass SpectrometryABSTRACT
Alkaloids derived from natural products have been traditionally used to treat various diseases, including cancers. Rutaecarpine (1), a ß-carboline-type alkaloid obtained from Evodia rutaecarpa, has been previously reported as an anti-inflammatory agent. Nonetheless, its anticancer activity and the underlying molecular mechanisms remain to be explored. In the procurement of Wnt/ß-catenin inhibitors from natural alkaloids, 1 was found to exhibit activity against the Wnt/ß-catenin-response reporter gene. Since the abnormal activation of Wnt/ß-catenin signaling is highly involved in colon carcinogenesis, the antitumor activity and molecular mechanisms of 1 were investigated in colorectal cancer (CRC) cells. The antiproliferative activity of 1 was associated with the suppression of the Wnt/ß-catenin-mediated signaling pathway and its target gene expression in human CRC cells. 1 also induced G0/G1 cell cycle arrest and apoptotic cell death, and the antimigration and anti-invasion potential of 1 was confirmed through epithelial-mesenchymal transition biomarker inhibition by the regulation of Wnt signaling. The antitumor activity of 1 was supported in an Ls174T-implanted xenograft mouse model via Wnt target gene regulation. Overall, these findings suggest that targeting the Wnt/ß-catenin signaling pathway by 1 is a promising therapeutic option for the treatment of human CRC harboring ß-catenin mutation.
Subject(s)
Colorectal Neoplasms , Wnt Signaling Pathway , Animals , Apoptosis , Cell Line, Tumor , Cell Proliferation , Colorectal Neoplasms/drug therapy , Humans , Indole Alkaloids , Mice , Quinazolines , beta CateninABSTRACT
The development of anticancer drugs remains challenging owing to the potential for drug resistance. The simultaneous inhibition of multiple targets involved in cancer could overcome resistance, and these agents would exhibit higher potency than single-target inhibitors. Protein kinases represent a promising target for the development of anticancer agents. As most multi-kinase inhibitors are heterocycles occupying only the hinge and hydrophobic region in the ATP binding site, we aimed to design multi-kinase inhibitors that would occupy the ribose pocket, along with the hinge and hydrophobic region, based on ATP-kinase interactions. Herein, we report the discovery of a novel 4'-thionucleoside template as a multi-kinase inhibitor with potent anticancer activity. The in vitro evaluation revealed a lead 1g (7-acetylene-7-deaza-4'-thioadenosine) with potent anticancer activity, and marked inhibition of TRKA, CK1δ, and DYRK1A/1B kinases in the kinome scan assay. We believe that these findings will pave the way for developing anticancer drugs.
ABSTRACT
Although docetaxel-based regimens are common and effective for early-stage triple-negative breast cancer (TNBC) treatment, acquired drug resistance frequently occurs. Therefore, a novel therapeutic strategy for docetaxel-resistant TNBC is urgently required. Signal transducer and activator of transcription 3 (STAT3) plays a pivotal role in the tumorigenesis and metastasis of numerous cancers, and STAT3 signaling is aberrantly activated in TNBC cells. In this study, a docetaxel-resistant TNBC cell line (MDA-MB-231-DTR) was established, and mechanisms for the antitumor activity of pulvomycin, a novel STAT3 inhibitor isolated from marine-derived actinomycete, were investigated. Levels of activated STAT3 (p-STAT3 (Y705)) increased in docetaxel-resistant cells, and knockdown of STAT3 recovered the sensitivity to docetaxel in MDA-MB-231-DTR cells. Pulvomycin effectively inhibited the proliferation of both cell lines. In addition, pulvomycin suppressed the activation of STAT3 and subsequently induced G0/G1 cell cycle arrest and apoptosis. Pulvomycin also significantly inhibited the invasion and migration of MDA-MB-231-DTR cells through the modulation of epithelial-mesenchymal transition markers. In an MDA-MB-231-DTR-bearing xenograft mouse model, the combination of pulvomycin and docetaxel effectively inhibited tumor growth through STAT3 regulation. Thus, our findings demonstrate that the combination of docetaxel and STAT3 inhibitors is an effective strategy for overcoming docetaxel resistance in TNBC.
ABSTRACT
Colorectal cancer (CRC) is a common and intractable malignancy with a high mortality risk. Conventional chemotherapeutics are effective for patients with early stage CRC, but the majority of deaths of CRC patients are linked to acquired drug resistance or metastasis occurrence. Asperphenin B (1), a lipopeptidyl benzophenone isolated from a marine-derived Aspergillus sp. fungus, reportedly possesses antiproliferative activity against cancer cells. However, its antitumor activity and the underlying molecular mechanisms remain unexplored. In this study, 1 induced G2/M phase cell cycle arrest and subsequent apoptotic cell death and inhibited tumor growth in a xenograft model. The 1-induced G2/M phase arrest was associated with the regulation of checkpoint proteins, including Chk1/2 and Cdc25c. The 1-induced apoptosis was correlated with an upregulation of p53 and cleaved caspases and a downregulation of survivin. Further experiments revealed that 1-mediated suppression of migration and invasion of metastatic HCT116 cells was partially associated with the downregulation of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) expression. The antimetastatic potential of 1 was also confirmed by E-cadherin upregulation and N-cadherin and Snail downregulation, which were in turn associated with the GAPDH regulation. These findings highlight the potential use of 1 as a novel candidate for treating metastatic CRC with the modulation of GAPDH function.
Subject(s)
Antineoplastic Agents/pharmacology , Aspergillus/chemistry , Benzophenones/pharmacology , Colorectal Neoplasms/drug therapy , Glyceraldehyde-3-Phosphate Dehydrogenases/antagonists & inhibitors , Animals , Antigens, CD , Apoptosis/drug effects , Aquatic Organisms/chemistry , Cadherins , G2 Phase Cell Cycle Checkpoints/drug effects , HCT116 Cells , Humans , Male , Mice, Inbred BALB C , Mice, Nude , Molecular Structure , Xenograft Model Antitumor AssaysABSTRACT
Due to a lack of hormone receptors, current treatment strategies for triple-negative breast cancer (TNBC) are limited with frequent disease recurrence and metastasis. Recent findings have suggested that aberrant methylation of histone H3 lysine 79 residue (H3K79me) by the histone methyltransferase disruptor of telomeric silencing 1-like (DOT1L) is a potential therapeutic target for TNBC clinical management. Therefore, we developed DOT1L inhibitors as potential antitumor agents against TNBC cells. We reveal that a synthetic half-selenopsammaplin A analog 9l (subsequently known as 9l) exhibited inhibitory activity against DOT1L-mediated H3K79 methylation, and showed antitumor activity in TNBC cells. The analog 9l also significantly inhibited TNBC invasion and migration via the modulation of epithelial-mesenchymal transition (EMT) markers, including N-cadherin and vimentin downregulation and E-cadherin upregulation. In an MDA-MB-231/Luc-implanted orthotopic mouse metastasis model, treatment with 9l effectively inhibited tumor growth and lung metastasis via DOT1L regulatory activity and EMT processes. Taken together, these findings highlight the potential of 9l as a novel therapeutic candidate for treating metastatic TNBC via DOT1L modulation.