Preparation of bicyclo[1.1.1]pentane-derived nucleoside analogues.

Nucleoside analogues are prevalent in drug design and call for more diversified structures. Bicyclo[1.1.1]pentane (BCP) structure has recently found wide applications in drug discovery. However, incorporation of BCP fragment into nucleoside analogues is hitherto unknown. Thus, from readily available BCP-containing building blocks, six new compounds, including pyrimidine nucleoside analogues, purine nucleoside analogues, and C-nucleoside analogues were prepared in 1-4 steps, generally with good yields.

A new BET inhibitor, 171, inhibits tumor growth through cell proliferation inhibition more than apoptosis induction.

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.

A 17 gene panel for non-small-cell lung cancer prognosis identified through integrative epigenomic-transcriptomic analyses of hypoxia-induced epithelial-mesenchymal transition.

As a critical feature of the tumor microenvironment, hypoxia is known to be a potent inducer of tumor metastasis, and it has been proposed that the initial steps in metastasis involve epithelial-mesenchymal transition (EMT). The strong correlation among hypoxia, EMT, and metastasis suggests that integrative assessment of gene expression and the DNA modification program of hypoxia-induced EMT via high-throughput sequencing technologies may increase our understanding of the molecular basis of tumor invasion and metastasis. Here, we present the genomewide transcriptional and epigenetic profiles of non-small-cell lung cancer (NSCLC) cells under normoxic and hypoxic conditions. We demonstrate that hypoxia induces EMT along with dynamic alterations of transcriptional expression and epigenetic modifications in both A549 and HCC827 cells. After training using a dataset from patients with invasive and noninvasive lung adenocarcinomas with an artificial neural network algorithm, a characteristic 17-gene panel was identified, consisting of genes involved in EMT, hypoxia response, glycometabolism, and epigenetic modifications. This 17-gene signature clearly stratified NSCLC patients with significant differences in overall survival across three independent datasets. Our study may be suitable as a basis for further selection of gene signatures to potentially guide prognostic stratification in patients with NSCLC.

Tranylcypromine and 6-trifluoroethyl thienopyrimidine hybrid as LSD1 inhibitor.

Tranylcypromine moiety extracted from LSD1 inhibitors and 6-trifluoroethyl thienopyrimidine moiety from menin-MLL1 PPI inhibitors were merged to give new chemotypes for medicinal chemistry study. Among 15 new compounds prepared in this work, some exhibited nanomolar LSD1 activity and good selectivity over MAO-A/B, low micromolar menin-MLL1 PPI inhibitory activity, as well as submicromolar MV4-11 antiprofilative activities. Intracellular LSD1 engagement of compounds with higher enzymatic and antiproliferative activities was confirmed by CD86 mRNA up-regulation experiments.

Ilex latifolia Thunb protects mice from HFD-induced body weight gain.

Kuding tea is implicated in alleviating metabolic disorders in traditional Chinese medicine. However, the role of Ilex latifolia Thunb (kuding tea), one of the large leaf kuding tea species, in the prevention of the development of obesity remains to be determined. We show here that 7-week-old male mice treated with an Ilex latifolia Thunb supplement for 14 weeks were resistant to HFD-induced body weight gain and hepatic steatosis, accompanied by improved insulin sensitivity. Ilex latifolia Thunb supplementation dramatically reduced the systemic and tissue inflammation levels of mice via reducing pro-inflammatory cytokine levels, increasing anti-inflammatory cytokine levels in the circulation and inhibiting p38 MAPK and p65 NF-κB signaling in adipose tissue. Together, these results indicate that Ilex latifolia Thunb protects mice from the development of obesity and is a potential compound pool for the development of novel anti-obesity drugs.

Preparation of 5'-deoxy-5'-amino-5'-C-methyl adenosine derivatives and their activity against DOT1L.

From a readily available 5-C-Me ribofuranoside, we have realized a reliable route to valuable 5'-deoxy-5'-amino-5'-C-methyl adenosine derivatives at gram scale with confirmed stereochemistry. These adenosine derivatives are useful starting materials for the preparation of 5'-deoxy-5'-amino-5'-C-methyl adenosine derivatives with higher complexity. From one of the new adenosine derivatives, some 5'-deoxy-5'-amino-5'-C-methyl adenosine DOT1L inhibitors were prepared in several steps. Data from DOT1L assay indicated that additional 5'-C-Me group improved the enzyme inhibitory activity.

A 2-Hydroxyisoquinoline-1,3-Dione Active-Site RNase H Inhibitor Binds in Multiple Modes to HIV-1 Reverse Transcriptase.

The RNase H (RNH) function of HIV-1 reverse transcriptase (RT) plays an essential part in the viral life cycle. We report the characterization of YLC2-155, a 2-hydroxyisoquinoline-1,3-dione (HID)-based active-site RNH inhibitor. YLC2-155 inhibits both polymerase (50% inhibitory concentration [IC50] = 2.6 µM) and RNH functions (IC50 = 0.65 µM) of RT but is more effective against RNH. X-ray crystallography, nuclear magnetic resonance (NMR) analysis, and molecular modeling were used to show that YLC2-155 binds at the RNH-active site in multiple conformations.

ω-3 free fatty acids and all-trans retinoic acid synergistically induce growth inhibition of three subtypes of breast cancer cell lines.

All-trans retinoic acid (ATRA), one of vitamin A derivatives, shows greater growth inhibition of breast cancer cell for ER-positive than ER-negative cells, while triple negative breast cancer cell such as MDA-MB-231 cell is poorly responsive to ATRA treatment. In this study, we found that combination of ω-3 free fatty acids (ω-3 FFAs) and ATRA exhibited synergistic inhibition of cell growth in three subtypes (ER+ MCF7, HER2+ SK-BR-3, Triple negative HCC1806 and MDA-MB-231 cells) of human breast cancer cell lines. The combined treatment of ω-3 FFAs and ATRA resulted in cell cycle arrest. ω-3 FFAs combined with ATRA synergistically provoked cell apoptosis via the caspase signals but not p53. These findings suggest that combined chemotherapy of ω-3 FFAs with ATRA is beneficial for improvement of ATRA sensitivity in breast cancer cells.

Discovery of a series of dihydroquinoxalin-2(1H)-ones as selective BET inhibitors from a dual PLK1-BRD4 inhibitor.

Recent years have seen much effort to discover new chemotypes of BRD4 inhibitors. Interestingly, some kinase inhibitors have been demonstrated to be potent bromodomain inhibitors, especially the PLK1 inhibitor BI-2536 and the JAK2 inhibitor TG101209, which can bind to BRD4 with IC50 values of 0.025 µM and 0.13 µM, respectively. Although the concept of dual inhibition is intriguing, selective BRD4 inhibitors are preferred as they may diminish off-target effects and provide more flexibility in anticancer drug combination therapy. Inspired by BI-2536, we designed and prepared a series of dihydroquinoxalin-2(1H)-one derivatives as selective bromodomain inhibitors. We found compound 54 had slightly higher activity than (+)-JQ1 in the fluorescence anisotropy assay and potent antiproliferative cellular activity in the MM.1S cell line. We have successfully solved the cocrystal structure of 52 in complex with BRD4-BD1, providing a solid structural basis for the binding mode of compounds of this series. Compound 54 exhibited high selectivity over most non-BET subfamily members and did not show bioactivity towards the PLK1 kinase at 10 or 1 µM. From in vivo studies, compound 54 demonstrated a good PK profile, and the results from in vivo pharmacological studies clearly showed the efficacy of 54 in the mouse MM.1S xenograft model.

Synthesis, biological evaluation and molecular modeling of 2-Hydroxyisoquinoline-1,3-dione analogues as inhibitors of HIV reverse transcriptase associated ribonuclease H and polymerase.

Human immunodeficiency virus (HIV) reverse transcriptase (RT) associated ribonuclease H (RNase H) remains the only virally encoded enzymatic function not clinically validated as an antiviral target. 2-Hydroxyisoquinoline-1,3-dione (HID) is known to confer active site directed inhibition of divalent metal-dependent enzymatic functions, such as HIV RNase H, integrase (IN) and hepatitis C virus (HCV) NS5B polymerase. We report herein the synthesis and biochemical evaluation of a few C-5, C-6 or C-7 substituted HID subtypes as HIV RNase H inhibitors. Our data indicate that while some of these subtypes inhibited both the RNase H and polymerase (pol) functions of RT, potent and selective RNase H inhibition was achieved with subtypes 8-9 as exemplified with compounds 8c and 9c.

Design and synthesis of benzylpiperidine inhibitors targeting the menin-MLL1 interface.

Menin is an essential oncogenic cofactor for mixed lineage leukemia (MLL)-mediated leukemogenesis, functioning through its direct interaction with MLL1 protein. Therefore, targeting the menin-MLL1 protein-protein interface represents a promising strategy to block MLL-mediated leukemogenesis. On the basis of co-crystal structure analysis, starting from thienopyrimidine chemotype, we have investigated the detailed structure-activity relationship of the piperazinyl-dihydrothiazole moiety. Several compounds were found with potent inhibitory activity against menin and better activities in cell-based experiments than MI-2-2. Molecular docking analysis revealed a less explored subpocket, which could be used for the design of new menin-MLL1 inhibitors.

Sorafenib exerts an anti-keloid activity by antagonizing TGF-ß/Smad and MAPK/ERK signaling pathways.

Keloid disease is characterized by hyperproliferation of responsive fibroblasts with vigorously continuous synthesis of extracellular matrix (ECM) components. Although the process by which keloids develop is poorly understood, most theories of the etiology are referred to fibroblast dysfunction. A central event in dermal repair is the release of growth factors in response to skin injury, which leads to the dysregulation of several crucial pathways that initiate the activation of keloid fibroblasts (KFs) and promote ECM accumulation. Hence, strategies aimed at reducing the production of these cytokines and/or disrupting their intracellular signal transduction have potential clinical significance for curing keloid. As the first oral multikinase inhibitor, sorafenib blocks a number of intracellular signaling pathways which are also pivotal for keloid pathogenesis. Therefore, evaluation of the effects of sorafenib on keloid disease seems timely and pertinent. In this study, we reported the identification of sorafenib that antagonized TGF-ß/Smad and MAPK/ERK signaling pathways in primary KFs. Impressively, treatment with sorafenib inhibited KF cell proliferation, migration, and invasion, and simultaneously reduced collagen production in KFs. Furthermore, we present ex vivo evidence that sorafenib induced the arrest of KF migration, the inhibition of angiogenesis, and the reduction of collagen accumulation. These preclinical observations suggest that sorafenib deserves systematic exploration as a candidate agent for the future treatment of keloids. KEY MESSAGE: The intracellular TGF-ß/Smad and MAPK/ERK signaling pathways is blocked by sorafenib. Sorafenib inhibits the proliferation, migration, invasion, and ECM deposition in keloid fibroblasts. Sorafenib reduces KF migration and concomitantly angiogenesis in keloid explants. Sorafenib is a promising agent for the treatment of keloids and hypertrophic scars.

Effects of Antitumor Drug Sorafenib on Chick Embryo Development.

Sorafenib has been used as an oral anti-cancer drug because of its ability to inhibit tumor growth. However, the pharmacological effect of sorafenib is still the lack of in vivo experimental evidence. Tumor and embryonic cells share some similar features, so we investigated the effects of sorafenib on the development of gastrulating chick embryos. We found that sorafenib exposure was markedly attributed to the number of embryonic cell in proliferation and apoptosis. We also detected sorafenib significantly interfered with epithelial-mesenchymal transition (EMT). Furthermore, sorafenib treatment impaired the production and migration of neural crest cells.

Design and optimization of a series of 1-sulfonylpyrazolo[4,3-b]pyridines as selective c-Met inhibitors.

c-Met has emerged as an attractive target for targeted cancer therapy because of its abnormal activation in many cancer cells. To identify high potent and selective c-Met inhibitors, we started with profiling the potency and in vitro metabolic stability of a reported hit 7. By rational design, a novel sulfonylpyrazolo[4,3-b]pyridine 9 with improved DMPK properties was discovered. Further elaboration of π-π stacking interactions and solvent accessible polar moieties led to a series of highly potent and selective type I c-Met inhibitors. On the basis of in vitro and in vivo pharmacological and pharmacokinetics studies, compound 46 was selected as a preclinical candidate for further anticancer drug development.

Fragment-based drug discovery of 2-thiazolidinones as BRD4 inhibitors: 2. Structure-based optimization.

The signal transduction of acetylated histone can be processed through a recognition module, bromodomain. Several inhibitors targeting BRD4, one of the bromodomain members, are in clinical trials as anticancer drugs. Hereby, we report our efforts on discovery and optimization of a new series of 2-thiazolidinones as BRD4 inhibitors along our previous study. In this work, guided by crystal structure analysis, we reversed the sulfonamide group and identified a new binding mode. A structure-activity relationship study on this new series led to several potent BRD4 inhibitors with IC50 of about 0.05-0.1 µM in FP binding assay and GI50 of 0.1-0.3 µM in cell based assays. To complete the lead-like assessment of this series, we further checked its effects on BRD4 downstream protein c-Myc, investigated its selectivity among five different bromodomain proteins, as well as the metabolic stability test, and reinforced the utility of 2-thiazolidinone scaffold as BET bromodomain inhibitors in novel anticancer drug development.

Multi-substituted 8-aminoimidazo[1,2-a]pyrazines by Groebke-Blackburn-Bienaymé reaction and their Hsp90 inhibitory activity.

Using a 2,3-diamino pyrazine substrate and yttrium triflate catalyst, various 2-alkyl and aryl substituted 3,8-diaminoimidazo[1,2-a]pyrazines were efficiently prepared through Groebke-Blackburn-Bienaymé MCR. In particular, a novel 2-piperonyl 3,8-diaminoimidazo[1,2-a]pyrazine structure was prepared exclusively with this new method and was found to have moderate Hsp90 inhibitory activity. A crystalline complex with N-terminus ATP domain of Hsp90 and one of the new Hsp90 inhibitors was also obtained to elucidate the origin of activity of 2-piperonyl 3,8-diaminoimidazo[1,2-a]pyrazines.

Strained olefin enables triflic anhydride mediated direct dehydrative glycosylation.

For the first time, we demonstrated that Tf2O mediated direct dehydrative glycosylation was possible simply with strained olefins, and other typical bases were inhibitors of this reaction. We optimized the glycosylation conditions and found that typical benzyl protected 1-OH pyranosyl donors and certain alcohol acceptors were suitable for our glycosylation system. Furthermore, we found that complete 1,2-trans selectivity and a wider acceptor scope could be achieved with 2-O-Bz 3,4,6-tri-O-Bn pyranosyl donors.

Editorial: advances in therapeutic glycopeptides.

Glycopeptides, peptides containing sugar ß-amino acids, have significant impact on medicinal chemistry research and pharmaceutical industr. In 1956, the discovery of one classic glycopeptide, vancomycin, broke the dawn of a new age for antibacterial research. Employing glycopeptides for the therapeutic purposes used to be regarded as proposals. Owing largely to the recent improvements in separation practices, characterization techniques, synthetic methods, and biological research, these proposals have been transformed into ongoing research projects in many laboratories around the world. Previously known as antibiotics, glycopeptides have been used as chemotherapeutic, antiviral, antitubercular, antifungal, antiproliferative and apoptotic agents. Nowadays they are even considered for the development of HIV and cancer vaccines. While several of them are in clinical trials, it could be expected that in the near future, treatment regimen of such difficult diseases might be reformed accordingly. Many interesting preliminary results are being produced in this emerging area. As witnesses and practitioners in this exciting area, however, we notice that the related communication in public domain is still limited due to the relatively small number of researchers involved. Thus, we feel the necessity to compile a timely issue about the special topic "Advances in Therapeutic Glycopeptides", covering state-of-the-art research papers and expert reviews from this area. We are glad that Protein & Peptide Letters is willing to realize the idea with us. The opening paper of this issue by Dr. Voglmeir and coauthor discusses three types of PNGases in respect of their general properties and applications of the commercially available PNGases in glycopeptide and glycoprotein analysis. Dr. Liu and coauthors describe current techniques such as high-performance liquid chromatography (HPLC), capillary electrophoresis (CE), and mass spectrometry (MS), for the characterization of glycoproteins, with a focus on available therapeutic glycoproteins. Next three papers discuss the synthetic chemistry of glycopeptides. Dr. Zhu and coauthor describe a facile synthesis of differently protected cystathionines by the reaction of γ-bromohomoalanine with cysteine derivatives in an ethyl acetate/water biphasic system. Dr. Chen et al. report a neoglycopeptides synthesis by aqueous Suzuki-Miyaura reaction between glycosyl boronic acid and iodopeptides. Dr. Zeng et al. developed a novel strategy to prepare glycopeptide-based molecular imaging and therapy agents using fluorine-rich (fluorous) technology. The following review by Dr. Li et al. outlines a sample of mAbs currently approved for cancer treatment by the FDA, as well as antibody platforms in the research pipeline and clinic that have been engineered for greater tumor penetration, binding, and therapy efficacy. The asialoglycoprotein receptor (ASGPR) is a high-capacity C-type lectin receptor expressed on mammalian hepatocytes. Research in this field is summarized by Dr. Lu, Dr. Yin and coauthors. Recent progresses of cationic polysomes and liposomes as effective non-viral delivery system via ASGPR are also presented by these authors. Proteoglycans (PGs), a core protein and glycosaminoglycans (GAGs) chain, play important roles in amyloid-beta protein as well as tau processing, and have potential significance in Alzheimer's disease (AD) therapy. Next, Dr. Zeng and coworkers summarized recent advances of the chemistry and biology of glycopeptides with antibiotic activity. The last review of this issue by Dr. Ding and coworker provide the progress of PGs and GAGs in AD and their therapeutic implication. In summary, experts from different fields of therapeutic glycopeptides have showcased new results and expressed their opinions in this special thematic issue of Protein & Peptide Letters. As the guest editors, we wish that this diverse collection of valuable intellectual contributions will positively influence this emerging area and gain broad readership. At the end, we would like to express our sincerest gratitude to all authors and referees for their invaluable contribution to this issue. We would also like to extend our appreciation to Editor-in-Chief, Professor Ben M. Dunn and the staffs of Protein & Peptide Letters, especially Ms Rukhshanda Rehman, for their excellent support and for providing us with the opportunity to pursue this exciting project.

1,2-Tans-1-dihydroxyboryl benzyl S-glycoside as glycosyl donor.

Activated by NBS, readily available 1,2-trans-1-dihydroxyboryl benzyl S-glycosides served as glycosyl donors and reacted with certain simple alcohol acceptors to produce pure 1,2-cis-O-glycosides in moderate yields. The boronic acid moiety was revealed essential in the glycosylation for product formation and good anomeric ratio. The preliminary model reactions suggested that glycosyl aryl boronic acids could be used for stereoselective glycosylation.