Discovery of seneciobipyrrolidine derivatives for the amelioration of glucose homeostasis disorders through 4E-BP1/Akt/AMPK signaling activation.

Modulating the glucose transport in skeletal muscle is a promising strategy for ameliorating glucose homeostasis disorders. However, the complicated mechanisms of glucose transport make it difficult to find compounds therapeutically relevant molecular mechanisms of action, while phenotypic screening is thought to be an alternative approach to mimic the cell state of interest. Here, we report (±)-seneciobipyrrolidine (1a) is first found to enhance glucose uptake in L6 myotubes through phenotype-based screening. Further SAR investigation led to the identfication of compound A27 (EC50 = 2.7 µM). Proteomiic analysis discloses the unique function mechanism of A27 through upregulating the level of the eukaryotic translation initiation factor 4E-binding protein 1 (4E-BP1), subsequently enhancing the Akt and AMPK phosphorylation, thereby promoting the glucose uptake. Chronic oral administration of A27 significantly lowers blood glucose and improves glucose tolerance in db/db mice. This work is new research on seneciobipyrrolidine derivatives, providing a promising avenue for ameliorating glucose homeostasis.

Downregulation of c-Myc expression confers sensitivity to CHK1 inhibitors in hematologic malignancies.

Checkpoint kinase 1 inhibitors (CHK1i) have shown impressive single-agent efficacy in treatment of certain tumors, as monotherapy or potentiators of chemotherapy in clinical trials, but the sensitive tumor types and downstream effectors to dictate the therapeutic responses to CHK1i remains unclear. In this study we first analyzed GDSC (Genomics of Drug Sensitivity in Cancer) and DepMap database and disclosed that hematologic malignancies (HMs) were relatively sensitive to CHK1i or CHK1 knockdown. This notion was confirmed by examining PY34, a new and potent in-house selective CHK1i, which exhibited potent anti-HM effect in vitro and in vivo, as single agent. We demonstrated that the downregulation of c-Myc and its signaling pathway was the common transcriptomic profiling response of sensitive HM cell lines to PY34, whereas overexpressing c-Myc could partially rescue the anticancer effect of PY34. Strikingly, we revealed the significant correlations between downregulation of c-Myc and cell sensitivity to PY34 in 17 HM cell lines and 39 patient-derived cell (PDC) samples. Thus, our results demonstrate that HMs are more sensitive to CHK1i than solid tumors, and c-Myc downregulation could represent the CHK1i efficacy in HMs.

Discovery of N-((3S,4S)-4-(3,4-Difluorophenyl)piperidin-3-yl)-2-fluoro-4-(1-methyl-1H-pyrazol-5-yl)benzamide (Hu7691), a Potent and Selective Akt Inhibitor That Enables Decrease of Cutaneous Toxicity.

Rash is one of the primary dose-limiting toxicities of Akt (protein kinase B) inhibitors in clinical trials. Here, we demonstrate the inhibition of Akt2 isozyme may be a driver for keratinocyte apoptosis, which promotes us to search for new selective Akt inhibitors with an improved cutaneous safety property. According to our previous research, compound 2 is selected for further optimization for overcoming the disadvantages of compound 1, including high Akt2 inhibition and high toxicity against HaCaT keratinocytes. The dihedral angle-based design and molecular dynamics simulation lead to the identification of Hu7691 (B5) that achieves a 24-fold selectivity between Akt1 and Akt2. Hu7691 exhibits low activity in inducing HaCaT apoptosis, promising kinase selectivity, and excellent anticancer cell proliferation potencies. Based on the superior results of safety property, pharmacokinetic profile, and in vivo efficacy, the National Medical Products Administration (NMPA) approved the investigational new drug (IND) application of Hu7691.

Discovery of 5,6-Bis(4-methoxy-3-methylphenyl)pyridin-2-amine as a WSB1 Degrader to Inhibit Cancer Cell Metastasis.

The gain of cell motility is an essential prerequisite for cancer metastasis. The ubiquitin ligase subunit WD repeat and SOCS box-containing 1 (WSB1) has been demonstrated to regulate hypoxia-driven tumor cell migration. However, there is still a lack of methods for discovering inhibitors targeting the WSB1 axis. Here, we employed phenotypic screening models and identified compound 4 that displayed migration inhibitory activity against WSB1-overexpressing cells. Further studies indicated that it may function as a WSB1 degrader, thus leading to the accumulation of the Rho guanosine diphosphate dissociation inhibitor 2 (RhoGDI2) protein, reversing the expression of downstream F-actin and formation of membrane ruffles, and disturbing the migration capacity of cancer cells. Moreover, compound 4 exhibited a promising in vivo anticancer metastatic effects. Our findings show the discovery of a new WSB1 degrader, providing a unique solution for the treatment of cancer metastasis.

Discovery of 1,5-Dihydro-4H-imidazol-4-one Derivatives as Potent, Selective Antagonists of CXC Chemokine Receptor 2.

CXC chemokine receptors 1 (CXCR1) and 2 (CXCR2) have been demonstrated to have critical roles in cancer metastasis. Because they share high homology sequences, it is still unclear how to design selective CXCR1 or CXCR2 antagonists. Based on a pharmacophore model we built, compound 2 bearing a 1,5-dihydro-4H-imidazol-4-one scaffold was identified as a selective CXCR2 antagonist with a low CXCR1 antagonism preference. Further optimization and structure-activity relationship studies led to compound C5 that overcame the disadvantages of compound 2 and performed with higher selectivity. It showed excellent oral bioavailability and in vitro anticancer metastasis activity. Further dynamic simulation of the molecular protein complex showed that the amino acid residue K320 of CXCR2 contributed most to the selectivity of C5. This study provides important clues for the design of new CXCR2 selective antagonists, and C5 can be a molecular tool for investigating the difference in the biological function of CXCR1 and CXCR2.

Identification of N-phenyl-3-methoxy-4-pyridinones as orally bioavailable H3 receptor antagonists and ß-amyloid aggregation inhibitors for the treatment of Alzheimer's disease.

Based on our previous work, a series of N-phenyl-3-methoxy-4-pyridinone derivatives were designed as orally bioavailable dual functional agents for therapy of Alzheimer's disease, through introducing alkyloxy moiety into 4-pyridinone ring to avoid the possible phase II metabolism of 3-hydroxy-4-pyridinone in lead compound 3-hydroxy-2-methyl-1-(4-(3-(pyrrolidin-1-yl)propoxy)phenyl)-pyridin-4(1H)-one (4). In vitro studies indicated that most of these compounds exhibit excellent H3 receptor antagonistic activities and potent self-induced Aß1-40/Aß1-42 aggregation inhibitory activities. In particular, 3-methoxy-1-(4-(3-(pyrrolidin-1-yl)propoxy)phenyl)-pyridin-4(1H)-one (7i) demonstrated IC50 value of 0.52 nM in H3R antagonism and good selectivity over other histamine receptor subtypes. The transmission electron microscopy (TEM) images showed that compound 7i can inhibit self-mediated Aß1-40/Aß1-42 aggregation efficiently. As expected, it exhibited desirable pharmacokinetic properties in plasma and good BBB permeability. Furthermore, compound 7i can efficiently block (R)-α-methylhistamine- induced dipsogenia and reverse scopolamine-induced learning deficits of rats. All above results indicated that compound 7i was a promising orally bioavailable dual functional agents with potential use in the treatment of Alzheimer's disease.

Selectivity Comparison of Tumor-Imaging Probes Designed Based on Various Tumor-Targeting Strategies: A Proof of Concept Study.

Fluorescence probes are emerging as appealing tools for tumor imaging, although the discovery of ideal probes with high tumor selectivity and desirable tumor-to-normal contrast remains challenging. There are currently two strategies used for designing tumor-targeted probes. One is employing tumor-targeting agents and the other is tumor-microenvironment-activatable probes. Although these two strategies have been widely explored, there are few reports on the comparison of probe performance designed based on the two strategies. Herein, by targeting somatostatin receptors (SSTR) overexpressed in neuroendocrine tumors with octreotide (OCT), we have designed two probes, with probe P5 being tumor-microenvironment-activatable and P5cc3 having fluorescence always on. A comparison of their selectivity toward tumor cells over SSTR-expressing normal cells demonstrated that these two probes showed a similar degree of tumor selectivity, whereas the activatable probe P5 showed enhanced tumor-to-normal imaging contrast due to its tumor-microenvironment-activatable fluorescence. Our results consolidate the rationality of either strategy for designing tumor-targeted imaging agents, and highlight the activatable strategy as a feasible way of enhancing tumor-to-normal imaging contrast.

An inherently kidney-targeting near-infrared fluorophore based probe for early detection of acute kidney injury.

Acute kidney injury (AKI) is common in hospital patients. Delayed diagnosis and treatment of AKI due to the lack of efficient early diagnosis is an important cause of its high mortality. While fluorescence imaging seems promising to non-intrusively interrogate AKI-related biomarkers, the low kidney contrast of many fluorophores conferred by their relatively low abundance of distribution in the kidney limits their application for AKI detection. Herein, we discovered a near-infrared fluorophore with inherent kidney-targeting ability. Based on this fluorophore, a fluorogenic probe (KNP-1) was developed by targeting peroxynitrite (ONOO-), which is upregulated at the early onset of AKI. KNP-1 exhibits desirable kidney distribution after intravenous administration and is fluorescent only after activation by ONOO-. These properties lead to excellent kidney contrast imaging results. KNP-1 is capable of detecting both nephrotoxin-induced and ischemia-reperfusion injury-induced AKI in live mice. Temporally resolved imaging of AKI-disease model mice with KNP-1 suggests a gradual increase in renal ONOO- levels with disease progression. Notably, the upregulation of ONOO- can be observed at least 24 h earlier than the clinically popular sCr and BUN methods. Blocking ONOO- generation also proves beneficial. These results highlight the applicability of this inherently tissue targeting-based strategy for designing probes with desirable imaging contrast; potentiate ONOO- as a biomarker and target for AKI early diagnosis and medical intervention; and imply the clinical relevance of KNP-1 for AKI early detection.

Structure-based design, synthesis and bioactivity evaluation of macrocyclic inhibitors of mutant isocitrate dehydrogenase 2 (IDH2) displaying activity in acute myeloid leukemia cells.

The enzymes involved in the metabolic pathways in cancer cells have been demonstrated as important therapeutic targets such as the isocitrate dehydrogenase 2 (IDH2). A series of macrocyclic derivatives was designed based on the marketed IDH2 inhibitor AG-221 by using the conformational restriction strategy. The resulted compounds showed moderate to good inhibitory potential against different IDH2-mutant enzymes. Amongst, compound C6 exhibited better IDH2R140Q inhibitory potency than AG-221, and showed excellent activity of 2-hydroxyglutarate (2-HG) suppression in vitro and its mesylate displayed good pharmacokinetic profiles. Moreover, C6 performed strong binding mode to IDH2R140Q after computational docking and dynamic simulation, which may serve as a good starting point for further development.

Recent advances in FLT3 inhibitors for acute myeloid leukemia.

Fms-like tyrosine kinase-3 (FLT3) mutations occur in approximately 30% of acute myeloid leukemia (AML) cases, suggesting FLT3 as an attractive target for AML treatment. Early FLT3 inhibitors enhance antileukemia efficacy by inhibiting multiple targets, and thus had stronger off-target activity, increasing their toxicity. Recently, a number of potent and selective FLT3 inhibitors have been developed, many of which are effective against multiple mutations. This review outlines the evolution of AML-targeting FLT3 inhibitors by focusing on their chemotypes, selectivity and activity over FLT3 wild-type and FLT3 mutations as well as new techniques related to FLT3. Compounds that currently enter the late clinical stage or have entered the market are also briefly reported.

Structurally novel PI3Kδ/γ dual inhibitors characterized by a seven-membered spirocyclic spacer: The SARs investigation and PK evaluation.

Herein, we communicate our recent medicinal chemistry efforts which have culminated in a series of PI3Kδ/γ dual inhibitors structurally featuring a seven-membered spirocyclic spacer. Compound 26, the most potent one among them, exhibited superior PI3Kδ inhibitory activity (IC50 = 1.0 nM) to that of the approved PI3Kδ inhibitor Idelalisib. Besides, it exerted remarkable anti-proliferative efficacy against human malignant B-cell line SU-DHL-6 with GI50 value of 33 nM. The biochemical assay against the other three class I PI3K isoforms identified compound 26 as a potent PI3Kδ/γ dual inhibitor with considerable selectivity over PI3Kα and PI3Kß. In SU-DHL-6 cells, a dramatic down-regulation of PI3K signaling was observed following compound 26-treatment at the concentration as low as 10 nM. Inspiringly, the pharmacokinetic (PK) study in Sprague-Dawley (SD) rats revealed it was orally available with a favorable bioavailability (F = 87.5%). Overall, compound 26, a promising PI3Kδ/γ dual inhibitor, has the potential to emerge as a clinical candidate for the treatment of leukocyte-mediated malignancies after extensive functional investigation.

Microenvironment-Responsive Small-Molecule Probe for Pulmonary Fibrosis Detection.

Pulmonary fibrosis (PF) is a fatal disease with increasing prevalence. Nonradioactive and noninvasive diagnosis of PF at an early stage can improve the prognosis but represents a daunting challenge. Up-regulation of nitric oxide (NO) is a typical microenvironmental feature of PF. Here, we report a small-molecule probe, PNO1, that can fluorogenically sense this microenvironmental feature for PF diagnosis. We demonstrate that PNO1 fluorescence is 6-fold higher in PF-diseased mice lungs than in normal-control groups. In addition to this in vivo result, PNO1 can also be applied in vitro to detect PF-diseased cells and ex vivo to detect PF-diseased tissues from clinical patients. These results highlight PNO1 as a complement to the traditional immunostaining-based methods for PF detection to facilitate quick screening for anti-PF drug candidates.

A fluorogenic probe for tracking GSH flux in developing neurons.

Understanding GSH flux in developing neurons is prerequisite to reveal its role in neuronal development but necessiates an ultrasensitive assay. By systematically exploring key structural factors determing probe sensitivity in live cells, we developed a fluorogenic probe capable of imaging subtle GSH fluctuations in developing neurons.

Design, synthesis, and biological study of 4-[(2-nitroimidazole-1H-alkyloxyl)aniline]-quinazolines as EGFR inhibitors exerting cytotoxicities both under normoxia and hypoxia.

PURPOSE: In order to get novel EGFR inhibitors exerting more potency in tumor hypoxia than in normoxia. METHODS: A series of 4-[(2-nitroimidazole-1H-alkyloxyl)aniline]-quinazolines were designed and synthesized, and their in vitro cytotoxicity and EGFR inhibitory activity were evaluated. Molecule docking study was performed for the representative compound. RESULTS: The structure-activity relationship (SAR) studies revealed that compounds bearing both meta-chloride and para-(2-nitroimidazole-1H-alkyloxy) groups on the aniline displayed potent inhibitory activities both in enzymatic and cellular levels. The most promising compound 16i potently inhibited EGFR with an IC50 value of 0.12 µM. Meanwhile, it manifested more potent cytotoxicity than the positive control lapatinib under tumor normoxia and hypoxia conditions (IC50 values of 1.59 and 1.09 µM against A549 cells, 2.46 and 1.35 µM against HT-29 cells, respectively). The proposed binding model of 16i in complex with EGFR was displayed by the docking results. CONCLUSION: This study provides insights for developing hypoxia-activated kinase inhibitors.

GSH Activated Biotin-tagged Near-Infrared Probe for Efficient Cancer Imaging.

Tumor imaging tools with high specificity and sensitivity are needed to aid the boundary recognition in solid tumor diagnosis and surgical resection. In this study, we developed a near infra-red (NIR) probe (P6) for in vitro/in vivo tumor imaging on the basis of the dual strategy of cancer cell targeting and stimulus-dependent activation. The selective imaging capacity towards cancer cells of P6 was thoroughly investigated, and the potential mechanisms of endocytosis were preliminary explored. Methods: GSH-activated biotin labelled NIR probe (P6) was designed, synthesized and characterized. The GSH responsive properties were systematically illustrated through UV-vis, fluorescent tests and LC-MS analysis. In vitro fluorescent imaging of probe P6 was collected in various living cancer cell lines (i.e. SW480, HGC-27, H460, BxPC-3, KHOS) and normal cell lines (i.e. BEAS-2B, HLF-1, THP1) under confocal laser scanning microscopy. Probe P6 was further applied to image primary human cancer cells which were freshly isolated from the peritoneal carcinoma and rectal cancer patients. Serial sections of human tumor tissues were collected and sent for H&E (hematoxylin-eosin) staining and P6 imaging. Live fluorescent and photoacoustic imaging were used to investigate the in vivo imaging of P6 in both tumor and normal tissues in HGC-27 and KHOS xenograft model. Results: Probe P6 could be recognized and transported into cancer cells by tumor specific biotin receptors and efficiently be triggered by GSH to release fluorophore 4. In fact, the cellular uptake of P6 could be partially blocked by the addition of free biotin. Furthermore, probe P6 could image various cancer cell lines, as well as primary cancer cells, exhibiting a ten-fold increase in fluorescence intensity over normal cells. In freshly dissected cancer tissues, P6 fluorescent imaging distinguished the cancerous area under confocal laser scanning microscopy, which was exact the same area as indicated by H&E staining. We also found that P6 exhibited superior selectivity against cancer tissues by local injection. Conclusion: In this study, we developed a dual-modal NIR probe P6 with enhanced cellular uptake into cancer cells and environmental stimulus triggered fluorescence. Our strategy provided a novel insight into the development of imaging tools that could be potentially used for fluorescent image-guided cancer boundary recognition and possibly cancer diagnosis.

Discovery of 3,4,6-Trisubstituted Piperidine Derivatives as Orally Active, Low hERG Blocking Akt Inhibitors via Conformational Restriction and Structure-Based Design.

A series of 3,4-disubstituted piperidine derivatives were obtained based on a conformational restriction strategy and a lead compound, A12, that exhibited potent in vitro and in vivo antitumor efficacies; however, obvious safety issues limited its further development. Thus, systematic exploration of the structure-activity relationship of compound A12, involving the phenyl group, hinge-linkage, and piperidine moiety, led to the discovery of the superior 3,4,6-trisubstituted piperidine derivative E22. E22 showed increased potency in Akt1 and cancer cell inhibition, remarkably reduced human ether-a-go-go-related gene blockage, and significantly improved safety profiles. Compound E22 also exhibited good kinase selectivity, had a good pharmacokinetic profile, and displayed very potent in vivo antitumor efficacy, with over 90% tumor growth inhibition in the SKOV3 xenograft model. Further mechanistic studies were conducted to demonstrate that compound E22 could significantly inhibit the phosphorylation of proteins downstream of Akt kinase in cells and tumor tissue from the xenograft model.

Discovery of pyrazole-thiophene derivatives as highly Potent, orally active Akt inhibitors.

A series of pyrazole-thiophene derivatives exhibiting good Akt inhibitory activities were obtained on the basis of conformational restriction strategy, leading to the discovery of compound 1d and 1o which showed excellent in vitro antitumor effect against a variety of hematologic cancer cells and their potential of inducing apoptosis, blocking the cell cycles at S phase and significantly inhibiting the phosphorylation of downstream biomarkers of Akt kinase of cancer cells. Amongst, compound 1o also exhibited good PK profiles and inhibited about 40% tumor growth in MM1S xenograft model. Compound 1o might be a potential candidate for further development.

Discovery of (R)-5-((5-(1-methyl-1H-pyrazol-4-yl)-4-(methylamino)pyrimidin-2-yl)amino)-3-(piperidin-3-yloxy)picolinonitrile, a novel CHK1 inhibitor for hematologic malignancies.

Through virtual screening, we identified the lead compound MCL1020, which exhibited modest CHK1 inhibitory activity. Then a series of 5-(pyrimidin-2-ylamino)picolinonitrile derivatives as CHK1 inhibitors were discovered by further rational optimization. One promising molecule, (R)-17, whose potency was one of the best, had an IC50 of 0.4 nM with remarkable selectivity (>4300-fold CHK1 vs. CHK2). Compound (R)-17 effectively inhibited the growth of malignant hematopathy cell lines especially Z-138 (IC50: 0.013 µM) and displayed low affinity for hERG (IC50 > 40 µM). Moreover, (R)-17 significantly suppressed the tumor growth in Z-138 cell inoculated xenograft model (20 mg/kg I.V., TGI = 90.29%) as a single agent with body weight unaffected. Taken together, our data demonstrated compound (R)-17 could be a promising drug candidate for the treatment of hematologic malignancies.

Design, synthesis and biological evaluation of novel benzothiadiazine derivatives as potent PI3Kδ-selective inhibitors for treating B-cell-mediated malignancies.

A series of 24 benzothiadiazine derivatives with structural novelty were designed, synthesized and biologically evaluated as PI3Kδ-selective inhibitors. As a consequence of the structure-activity relationship (SAR) study, compounds 63 and 71 were identified with single-digit nanomolar IC50 values against PI3Kδ and submicromolar GI50 values against human malignant B-cell line SU-DHL-6. Furthermore, chiral resolution of the key amine intermediate of these two compounds was performed to achieve corresponding enantiomers. In subsequent biological evaluation, S-63 (IC50: 4.6 nM) and S-71 (IC50: below 0.32 nM) demonstrated comparable and superior PI3Kδ inhibitory activity, respectively, to that of idelalisib. Additionally, both S-63 (GI50: 33.2 nM) and S-71 (GI50: 15.9 nM) exerted enhanced anti-proliferative activity against the SU-DHL-6 cell line than that of idelalisib. Moreover, both S-63 and S-71 exhibited excellent PI3Kδ selectivity. In the further in vivo pharmacokinetic (PK) study, S-63 displayed a good plasma exposure and an acceptable oral bioavailability of 29.2%. By virtue of its biological performance, S-63 merits further development as a potential therapeutic agent for battling B-cell-mediated malignancies.

Phenotypic Screening-Based Identification of 3,4-Disubstituted Piperidine Derivatives as Macrophage M2 Polarization Modulators: An Opportunity for Treating Multiple Sclerosis.

Multiple sclerosis (MS) is a disease of the autoimmune-mediated disorder in the central nervous system, for which no effective therapeutic agent is currently available. The regulation of macrophage polarization toward M2 is a general benefit for treating MS. The gene biomarker-based phenotypic screening approach was developed, and 3,4-disubstituted piperidine derivative S-28 was identified as a lead compound modulating macrophage M2 polarization. Further SAR studies resulted in the discovery of the most potent modulator D11 that showed good oral bioavailability and significant in vivo therapeutic effects. Mechanistic studies demonstrated that the M2 polarization macrophages modulated by D11 mainly functioned through inhibiting the proliferation of T-cells and activating the phosphorylation of Stat3 and Akt. Therefore, the gene biomarker-based phenotypic screening was demonstrated as a promising tool for the discovery of novel macrophage M2 polarization modulators. Compound D11 may serve as a promising starting point for the development of therapeutics to treat MS.