Microtubule-associated serine/threonine kinase-like (MASTL) is a primary regulator of mitosis and a potential cancer target. We report the discovery and optimization of MASTL kinase inhibitor-3 (MKI-3), a potent and selective MASTL inhibitor with nanomolar cellular activity and enhanced metabolic stability, suitable for in vivo assessment. Structure-activity relationship studies identified MKI-3, a quinazoline-based scaffold that enhances MASTL binding, suppresses endosulfine alpha (ENSA) phosphorylation, and activates protein phosphatase 2A. MKI-3 inhibited MASTL with a half-maximal inhibitory concentration of 5.72 nM and exhibited strong selectivity over other AGC kinases. In breast cancer cell lines (MCF7, MDA-MB-231, BT549, and 4T1), MKI-3 exhibited robust antiproliferative effects at nanomolar concentrations. Mechanistically, MKI-3 disrupted the MASTL-ENSA-Aurora A signaling axis, inducing chromosomal instability, mitotic catastrophe, and apoptosis. MKI-3 significantly reduced tumor growth in treatment-refractory 4T1 triple-negative breast cancer without toxicity and outperformed MKI-2 supporting MASTL-targeted therapy.

The cascade reaction is an attractive strategy for building fused heterocycles. We report the first synthetic methodology to construct (6R)‐6‐hydroxy‐1,3a,6,11a‐tetrahydro‐4H‐pyrazolo[3′,4′:4,5]pyrimido[2,1‐a]isoindol‐4‐one fused heterocycles based on a cascade sequence of Suzuki coupling to form a C−C bond and base‐mediated intramolecular cyclization to form a C−N bond. This protocol exhibits high stereospecificity, as intramolecular cyclization generates a chiral center with exclusive R‐configuration in the product. A mechanism for the cascade reaction is proposed based on density functional theory calculations.

MASTL is a mitotic kinase that inhibits PP2A via ENSA phosphorylation and is implicated in breast cancer progression. We developed MASTL inhibitor-3, a selective and metabolically stable small molecule with nanomolar potency (IC50 = 5 nM) and high specificity over other AGC kinases. Structure-based optimization of a quinazoline scaffold enhanced MASTL binding and suppressed ENSA phosphorylation, restoring PP2A activity. MASTL inhibitor-3 showed strong antiproliferative effects in MCF7, MDA-MB-231, BT549, and 4T1 breast cancer cells. It disrupted the MASTL–ENSA–Aurora A axis, leading to mitotic catastrophe and apoptosis. In a syngeneic 4T1 mouse model, it significantly inhibited tumor growth without detectable toxicity and outperformed a prior compound. These results highlight MASTL inhibitor-3 as a promising candidate for targeted breast cancer therapy. Ye-Hyun Kim, Ji-In Kim, Kwan-Young Jung, Jae-Sung Kim. Development and Preclinical Evaluation of a Potent and Selective MASTL Inhibitor for Breast Cancer Therapy [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics; 2025 Oct 22-26; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2025;24(10 Suppl):Abstract nr A086.

Small-cell lung cancer (SCLC) is highly lethal because the tumors grow and metastasize rapidly. Effective treatments for SCLC are lacking currently. A recent study demonstrated that the E1A binding protein P300 (EP300) KIX domain has pro-tumorigenic activity and is selectively involved in the development and growth of SCLC. These findings suggest the possibility of developing small-molecule inhibitors of EP300 KIX as new targeted therapies for SCLC. In this study, we reported the crystal structure of the human EP300 KIX domain at 2.9 & Aring; resolution except for a flexible loop and C-terminal end. The overall structure was almost identical to that of the cAMP response element-binding protein (CBP) KIX. Nine EP300 KIX residues were different from those of CBP KIX. Among these non-strictly conserved residues, Ala627, which corresponds to Asp647 in CBP KIX, reduces the negative surface potential. Asn581 and Arg613 contributed to the formation of additional hydrogen bonds in the EP300 KIX structure. Further structural analysis revealed that the hydrophobic residues that form the allosteric network in CBP KIX were well conserved in the EP300 KIX structure. This study lays the groundwork for structure-based drug design for SCLC.

AIMS:Sirtuin 7 (SIRT7) plays an important role in tumor development, and has been characterized as a potent regulator of cellular stress. However, the effect of SIRT7 on sorafenib acquired resistance remains unclear and a possible anti-tumor mechanism beyond this process in HCC has not been clarified. We examined the therapeutic potential of SIRT7 and determined whether it functions synergistically with sorafenib to overcome chemoresistance. METHODS:Cancer Genome Atlas-liver HCC data and unbiased gene set enrichment analyses were used to identify SIRT7 as a potential effector molecule in sorafenib acquired resistance. Two types of SIRT7 chemical inhibitors were developed to evaluate its therapeutic properties when synergized with sorafenib. Mass spectrometry was performed to discover a direct target of SIRT7, DDX3X, and DDX3X deacetylation levels and protein stability were explored. Moreover, an in vivo xenograft model was used to confirm anti-tumor effect of SIRT7 and DDX3X chemical inhibitors combined with sorafenib. RESULTS:SIRT7 inhibition mediated DDX3X depletion can re-sensitize acquired sorafenib resistance by disrupting NLRP3 inflammasome assembly, finally suppressing hyperactive ERK1/2 signaling in response to NLRP3 inflammasome-mediated IL-1β inhibition. CONCLUSIONS:SIRT7 is responsible for sorafenib acquired resistance, and its inhibition would be beneficial when combined with sorafenib by suppressing hyperactive pro-cell survival ERK1/2 signaling.

BRD4 contains two tandem bromodomains (BD1 and BD2) that recognize acetylated lysine for epigenetic reading, and these bromodomains are promising therapeutic targets for treating various diseases, including cancers. BRD4 is a well-studied target, and many chemical scaffolds for inhibitors have been developed. Research on the development of BRD4 inhibitors against various diseases is actively being conducted. Herein, we propose a series of [1,2,4]triazolo[4,3-b]pyridazine derivatives as bromodomain inhibitors with micromolar IC50 values. We characterized the binding modes by determining the crystal structures of BD1 in complex with four selected inhibitors. Compounds containing [1,2,4] triazolo[4,3-b]pyridazine derivatives offer promising starting molecules for designing potent BRD4 BD inhibitors.

Background The maintenance of spindle pole integrity is essential for spindle assembly and chromosome segregation during mitosis. However, the underlying mechanisms governing spindle pole integrity remain unclear. Methods ENSA was inhibited by siRNA or MKI-2 treatment and its effect on cell cycle progression, chromosome alignment and microtubule alignment was observed by immunohistochemical staining and western blotting. PP2A-B55α knockdown by siRNA was performed to rescue the phenotype caused by ENSA inhibition. The interaction between ENSA and Aurora A was detected by in situ PLA. Furthermore, orthotopic implantation of 4Tl-luc cancer cells was conducted to confirm the consistency between the in vitro and in vivo relationship of the ENSA-Aurora A interaction. Results During mitosis, p-ENSA is localized at the spindle poles, and the inhibition of ENSA results in mitotic defects, such as misaligned chromosomes, multipolar spindles, asymmetric bipolar spindles, and centrosome defects, with a delay in mitotic progression. Although the mitotic delay caused by ENSA inhibition was rescued by PP2A-B55α depletion, spindle pole defects persisted. Notably, we observed a interaction between ENSA and Aurora A during mitosis, and inhibition of ENSA reduced Aurora A expression at the mitotic spindle poles. Injecting MKI-2-sensitized tumors led to increased chromosomal instability and downregulation of the MASTL-ENSA-Aurora A pathway in an orthotopic breast cancer mouse model. Conclusions These findings provide novel insights into the regulation of spindle pole integrity by the MASTL-ENSA-Aurora A pathway during mitosis, highlighting the significance of ENSA in recruiting Aurora A to the spindle pole, independent of PP2A-B55α.

The FDA-approved oral multi-kinase inhibitor, sorafenib (BAY 43-9006, Nexavar), is the first approved systemic therapy for patients with unresectable hepatocellular carcinoma (HCC). Although it has been shown to significantly improve the overall survival of patients with HCC, drug resistance limits the response rate to this therapeutic. Here, we report that acquired sorafenib resistance is associated with overexpression of the deacetylase, SIRT7, and a high level of ERK phosphorylation. Further, we identify that the hyperactivation of ERK is controlled by SIRT7-mediated deacetylation of DDX3X. The inhibition of SIRT7 combined with sorafenib resulted in a marked reduction of cell viability in vitro and of tumor growth in vivo. It seems plausible that SIRT7 is responsible for the acquired sorafenib resistance and its inhibition is most likely beneficial together in conjunction with sorafenib by suppressing ERK signaling. Highlights Sorafenib resistance in HCC is associated with SIRT7 and ERK hyperactivation. Suppression of SIRT7 combined with sorafenib restores sensitivity to sorafenib. SIRT7 controls sorafenib resistance through ERK activation by mediating DDX3X deacetylation.

Treating acute myeloid leukemia (AML) by targeting FMS-like tyrosine kinase 3 (FLT-3) is considered an effective treatment strategy. By using AI-assisted hit optimization, we discovered a novel and highly selective compound with desired drug-like properties with which to target the FLT-3 (D835Y) mutant. In the current study, we applied an AI-assisted de novo design approach to identify a novel inhibitor of FLT-3 (D835Y). A recurrent neural network containing long short-term memory cells (LSTM) was implemented to generate potential candidates related to our in-house hit compound (PCW-1001). Approximately 10,416 hits were generated from 20 epochs, and the generated hits were further filtered using various toxicity and synthetic feasibility filters. Based on the docking and free energy ranking, the top compound was selected for synthesis and screening. Of these three compounds, PCW-A1001 proved to be highly selective for the FLT-3 (D835Y) mutant, with an IC50 of 764 nM, whereas the IC50 of FLT-3 WT was 2.54 μM.

Bromodomain and extra-terminal domain (BET) proteins have been considered as potent candidates for anti-cancer drug development. As epigenetic readers, they modulate gene expression by recognizing acetylated lysine residues on histones. Therefore, the pharmacological inhibition of BET proteins has been extensively studied. Herein, we report the novel chemical scaffold of N-(pyridin-2-yl)-1H-benzo[d][1,2,3]triazol-5-amine as BET inhibitors using high-throughput screening assay. Through the analysis of structure-activity relationships, we developed a potent novel compound, which exhibited a better IC50 value about 2-fold compared to iBet762 against the BRD4 bromodomain (BD). The addition of a sulfonyl group to the pyridine ring enhanced the inhibitory activity. Structural studies showed a clear electron density map for the inhibitor and revealed the structural basis for the critical role of the sulfonyl group in the interaction with BRD4.

As pyrazole and its derivatives have a wide range of biological activities, including anticancer activity, the design of novel pyrazole derivatives has emerged as an important research field. This study describes a novel pyrazole derivative that exerts antitumor and radiosensitizing activities in breast cancer both in vitro and in vivo. We synthesized a novel pyrazole compound N,N-dimethyl-N’-(3-(1-(4-(trifluoromethyl)phenyl)-1H-pyrazol-4-yl)phenyl)azanesulfonamide (PCW-1001) and showed that it inhibited several oncogenic properties of breast cancer both in vitro and in vivo. PCW-1001 induced apoptosis in several breast cancer cell lines. Transcriptome analysis of PCW-1001-treated cells showed that it regulates genes involved in the DNA damage response, suggesting its potential use in radiotherapy. Indeed, PCW-1001 enhanced the radiation sensitivity of breast cancer cells by modulating the expression of DNA damage response genes. Therefore, our data describe a novel pyrazole compound, PCW-1001, with antitumor and radiosensitizer activities in breast cancer.

Epigenetic regulation is known to play a key role in progression of anti-cancer therapeutics. Lysine acetylation is an important mechanism in controlling gene expression. There has been increasing interest in bromodomain owing to its ability to modulate transcription of various genes as an epigenetic ‘reader.’ Herein, we report the design, synthesis, and X-ray studies of novel aristoyagonine (benzo[6,7]oxepino[4,3,2-cd]isoindol-2(1H)-one) derivatives and investigate their inhibitory effect against Brd4 bromodomain. Five compounds 8ab, 8bc, 8bd, 8be, and 8bf have been discovered with high binding affinity over the Brd4 protein. Co-crystal structures of these five inhibitors with human Brd4 bromodomain demonstrated that it has a key binding mode occupying the hydrophobic pocket, which is known to be the acetylated lysine binding site. These novel Brd4 bromodomain inhibitors demonstrated impressive inhibitory activity and mode of action for the treatment of cancer diseases.

Since bromodomain containing 4 (brd4) has been considered as a prominent cancer target, numerous attempts have been made to develop potent brd4 bromodomain inhibitors. The present study provided a novel chemical scaffold which inhibited brd4 activity. Mid-throughput screening against brd4 bromodomain was performed using alpha-screen and homogeneous time-resolved fluorescence assays. Furthermore, cell cytotoxicity and xenograft assays were performed to examine if the compound was effective both in vitro and in vivo. As a result, it was revealed that compounds having naphthalene-1,4-dione scaffold inhibited the binding of bromodomain to acetylated histone. The compounds with naphthalene-1,4-dione had cytotoxic effects against the Ty82 cell line, a NUT midline carcinoma cell line, whose proliferation is dependent on brd4 activity. A10, one of the compounds with naphthalene-1,4-dione scaffold, also exhibited tumor growth inhibition effects in the xenograft assay. In addition, the compounds exhibited cytotoxic effects against gastric cancer cell lines which were resistant to I-BET-762, a BET bromodomain inhibitor. In conclusion, the novel scaffold to suppress brd4 activity was effective against cancer cells both in vitro and in vivo.

Although microtubule-associated serine/threonine kinase-like (MASTL) is a promising target for selective anticancer treatment, MASTL inhibitors with nano range potency and antitumor efficacy have not been reported. Here, we report a novel potent and selective MASTL inhibitor MASTL kinase inhibitor-2 (MKI-2) identified in silico through a drug discovery program. Our data showed that MKI-2 inhibited recombinant MASTL activity and cellular MASTL activity with IC50 values of 37.44 nM and 142.7 nM, respectively, in breast cancer cells. In addition, MKI-2 inhibited MASTL kinase rather than other AGC kinases, such as ROCK1, AKT1, PKACα, and p70S6K. Furthermore, MKI-2 exerted various antitumor activities by inducing mitotic catastrophe resulting from the modulation of the MASTL-PP2A axis in breast cancer cells. The MKI-2 treatment showed phenocopies with MASTL-null oocyte in mouse oocytes, which were used as a model to validate MKI-2 activity. Therefore, our study provided a new potent and selective MASTL inhibitor MKI-2 targeting the oncogenic MAST-PP2A axis in breast cancer cells.

The 11β-hydroxysteroiddehydrogenase type 1(11β-HSD1), acortisolregenerating enzyme that amplifies tissue glucocorticoidlevels, plays an important role in diabetes, obesity, and glaucoma and is recognized as a potential therapeutic target for various disease conditions. Moreover, a recent study demonstrated that selective 11β-HSD1 inhibitor can attenuate ischemic brain injury. This prompted us to optimize cyclic sulfamide derivative for aiming to treat ischemic brain injury. Among the synthesized compounds, 6e has an excellent in vitro activivity with an IC50 value of 1 nM toward human and mouse 11β-HSD1 and showed good 11β-HSD1 inhibition in ex vivo study using brain tissue isolated from mice. Furthermore, in the transient middle cerebral artery occlusion model in mice, 6e treatment significantly attenuated infarct volume and neurological deficit following cerebral ischemia/reperfusion injury. Additionally, binding modes of 6e for human and mouse 11β-HSD1 were suggested.

This paper aims to validate if intrapancreatic injection of penicillin G can enhance hardness and suture holding capacity (SHC) of the pancreas through prompting the fibrosis process. Soft pancreatic texture is constantly mentioned as one of the most contributory predictors of postoperative pancreatic fistula (POPF). Soft pancreas has poor SHC and higher incidence of parenchymal tearing, frequently leading to POPF. From a library of 114 antibiotic compounds, we identified that penicillin G substantially enhanced pancreatic hardness and SHC in experimental mice. Specifically, we injected penicillin G directly into the pancreas. On determined dates, we measured the pancreatic hardness and SHC, respectively, and performed molecular and histological examinations for estimation of the degree of fibrosis. The intrapancreatic injection of penicillin G activated human pancreatic stellate cells (HPSCs) to produce various fibrotic materials such as transforming growth factor-β1 (TGF-β1) and metalloproteinases-2. The pancreatic hardness and SHC were increased to the maximum at the second day after injection and then it gradually subsided demonstrating its reversibility. Pretreatment of mice with SB431542, an inhibitor of the TGF-β1 receptor, before injecting penicillin G intrapancreatically, significantly abrogated the increase of both pancreatic hardness and SHC caused by penicillin G. This suggested that penicillin G promotes pancreatic fibrosis through the TGF-β1 signaling pathway. Intrapancreatic injection of penicillin G promotes pancreatic hardness and SHC by enhancing pancreatic fibrosis. We thus think that penicillin G could be utilized to prevent and minimize POPF, after validating its actual effectiveness and safety by further studies.

Although MASTL (microtubule-associated serine/threonine kinase-like) is an attractive target for anticancer treatment, MASTL inhibitors with antitumor activity have not yet been reported. In this study, we have presented a novel MASTL inhibitor, MKI-1, identified through in silico screening and in vitro analysis. Our data revealed that MKI-1 exerted antitumor and radiosensitizer activities in in vitro and in vivo models of breast cancer. The mechanism of action of MKI-1 occurred through an increase in PP2A activity, which subsequently decreased the c-Myc protein content in breast cancer cells. Moreover, the activity of MKI-1 in the regulation of MASTL-PP2A was validated in a mouse oocyte model. Our results have demonstrated a new small-molecule inhibitor of MASTL, MKI-1, which exerts antitumor and radiosensitizer activities through PP2A activation in breast cancer in vitro and in vivo.

BACKGROUND The use of methyl-tertiary butyl ether (MTBE) to dissolve gallstones has been limited due to concerns over its toxicity and the widespread recognition of the safety of laparoscopic cholecystectomy. The adverse effects of MTBE are largely attributed to its low boiling point, resulting in a tendency to evaporate. Therefore, if there is a material with a higher boiling point and similar or higher dissolubility than MTBE, it is expected to be an attractive alternative to MTBE. AIM To determine whether tert-amyl ethyl ether (TAEE), an MTBE analogue with a relatively higher boiling point (102 °C), could be used as an alternative to MTBE in terms of gallstone dissolubility and toxicity. METHODS The in vitro dissolubility of MTBE and TAEE was determined by measuring the dry weights of human gallstones at predetermined time intervals after placing them in glass containers with either of the two solvents. The in vivo dissolubility was determined by comparing the weights of solvent-treated gallstones and control (dimethyl sulfoxide)-treated gallstones, after the direct infusion of each solvent into the gallbladder in both hamster models with cholesterol and pigmented gallstones. RESULTS The in vitro results demonstrated a 24 h TAEE-dissolubility of 76.7%, 56.5% and 38.75% for cholesterol, mixed, and pigmented gallstones, respectively, which represented a 1.2-, 1.4-, and 1.3-fold increase in dissolubility compared to that of MTBE. In the in vitro experiment, the 24 h-dissolubility of TAEE was 71.7% and 63.0% for cholesterol and pigmented gallstones, respectively, which represented a 1.4- and 1.9-fold increase in dissolubility compared to that of MTBE. In addition, the results of the cell viability assay and western blot analysis indicated that TAEE had a lower toxicity towards gallbladder epithelial cells than MTBE. CONCLUSION We demonstrated that TAEE has higher gallstone dissolubility properties and safety than those of MTBE. As such, TAEE could present an attractive alternative to MTBE if our findings regarding its efficacy and safety can be consistently reproduced in further subclinical and clinical studies.

The front cover picture, designed by Jaeuk Sim from the group of Heesoon Lee and Jae-Kyung Jung, illustrates the synthesis of 4-aryl-2-halopyridines via gamma-functionalization of alpha,beta-unsaturated nitriles. Our method features enamine formation at the gamma-position of vinylogous nitriles followed by cyclization to heteroaromatics. In commemoration of Christmas, this picture depicts the reagents gathered around the Christmas tree to create diverse heterocycles through the enamine intermediates. Details of this work can be found in the Update on pages xxxx-xxxx (J. Sim, M. Viji, J. Rhee, H. Jo, S. J. Cho, Y. Park, S.-Y. Seo, K.-Y. Jung, H. Lee, J.-K. Jung, Adv. Synth. Catal. 2019, 361, xxxx-xxxx; DOI: 10.1002/adsc.201901002).