Deep learning for de-convolution of Smad2 versus Smad3 binding sites.

BACKGROUND: The transforming growth factor beta-1 (TGF ß-1) cytokine exerts both pro-tumor and anti-tumor effects in carcinogenesis. An increasing body of literature suggests that TGF ß-1 signaling outcome is partially dependent on the regulatory targets of downstream receptor-regulated Smad (R-Smad) proteins Smad2 and Smad3. However, the lack of Smad-specific antibodies for ChIP-seq hinders convenient identification of Smad-specific binding sites. RESULTS: In this study, we use localization and affinity purification (LAP) tags to identify Smad-specific binding sites in a cancer cell line. Using ChIP-seq data obtained from LAP-tagged Smad proteins, we develop a convolutional neural network with long-short term memory (CNN-LSTM) as a deep learning approach to classify a pool of Smad-bound sites as being Smad2- or Smad3-bound. Our data showed that this approach is able to accurately classify Smad2- versus Smad3-bound sites. We use our model to dissect the role of each R-Smad in the progression of breast cancer using a previously published dataset. CONCLUSIONS: Our results suggests that deep learning approaches can be used to dissect binding site specificity of closely related transcription factors.

Designing a leucine-rich antibacterial nonapeptide with potent activity against mupirocin-resistant MRSA via a structure-activity relationship study.

Staphylococcus aureus is the main aetiological agent responsible for the majority of human skin infections. Of particular concern is the methicillin-resistant variety, commonly known as MRSA. The extensive use of the first-line topical antibiotic of choice, mupirocin, has inevitably resulted in the emergence of resistant strains, signalling an urgent need for the development of new antibacterials with new mechanisms of action. In this work, we describe how we designed a novel cationic nonapeptide, containing only leucine and two lysine residues, with potent anti-MRSA activity and a rapid bactericidal mode of action. Coupled to a favourable safety profile towards human skin fibroblasts, we believe nonapeptide 11 has high potential for further development as a mupirocin replacement candidate to treat skin infections caused by MRSA.

Correction to "Discovery of Irreversible Inhibitors Targeting Histone Methyltransferase, SMYD3".

[This corrects the article DOI: 10.1021/acsmedchemlett.9b00170.].

Discovery of Irreversible Inhibitors Targeting Histone Methyltransferase, SMYD3.

SMYD3 is a histone methyltransferase that regulates gene transcription, and its overexpression is associated with multiple human cancers. A novel class of tetrahydroacridine compounds which inhibit SMYD3 through a covalent mechanism of action is identified. Optimization of these irreversible inhibitors resulted in the discovery of 4-chloroquinolines, a new class of covalent warheads. Tool compound 29 exhibits high potency by inhibiting SMYD3's enzymatic activity and showing antiproliferative activity against HepG2 in 3D cell culture. Our findings suggest that covalent inhibition of SMYD3 may have an impact on SMYD3 biology by affecting expression levels, and this warrants further exploration.

Structure-Activity Relationship Studies of Mitogen Activated Protein Kinase Interacting Kinase (MNK) 1 and 2 and BCR-ABL1 Inhibitors Targeting Chronic Myeloid Leukemic Cells.

Clinically used BCR-ABL1 inhibitors for the treatment of chronic myeloid leukemia do not eliminate leukemic stem cells (LSC). It has been shown that MNK1 and 2 inhibitors prevent phosphorylation of eIF4E and eliminate the self-renewal capacity of LSCs. Herein, we describe the identification of novel dual MNK1 and 2 and BCR-ABL1 inhibitors, starting from the known kinase inhibitor 2. Initial structure-activity relationship studies resulted in compound 27 with loss of BCR-ABL1 inhibition. Further modification led to orally bioavailable dual MNK1 and 2 and BCR-ABL1 inhibitors 53 and 54, which are efficacious in a mouse xenograft model and also reduce the level of phosphorylated eukaryotic translation initiation factor 4E in the tumor tissues. Kinase selectivity of these compounds is also presented.

An FDA-Drug Library Screen for Compounds with Bioactivities against Meticillin-Resistant Staphylococcus aureus (MRSA).

The lack of new antibacterial drugs entering the market and their misuse have resulted in the emergence of drug-resistant bacteria, posing a major health crisis worldwide. In particular, meticillin-resistant Staphylococcus aureus (MRSA), a pathogen responsible for numerous human infections, has become endemic in hospitals worldwide. Drug repurposing, the finding of new therapeutic indications for approved drugs, is deemed a plausible solution to accelerate drug discovery and development in this area. Towards this end, we screened 1163 drugs approved by the Food and Drug Administration (FDA) for bioactivities against MRSA in a 10 µM single-point assay. After excluding known antibiotics and antiseptics, six compounds were identified and their MICs were determined against a panel of clinical MRSA strains. A toxicity assay using human keratinocytes was also conducted to gauge their potential for repurposing as topical agents for treating MRSA skin infections.

3-Deazaneplanocin A and neplanocin A analogues and their effects on apoptotic cell death.

3-Deazaneplanocin A (DzNep) is a potential epigenetic drug for the treatment of various cancers. DzNep has been reported to deplete histone methylations, including oncogenic EZH2 complex, giving rise to epigenetic modifications that reactivate many silenced tumor suppressors in cancer cells. Despite its promise as an anticancer drug, little is known about the structure-activity relationships of DzNep in the context of epigenetic modifications and apoptosis induction. In this study, a number of analogues of DzNep were examined for DzNep-like ability to induce synergistic apoptosis in cancer cells in combination with trichostatin A, a known histone deacetylase (HDAC) inhibitor. The structure-activity relationship data thus obtained provide valuable information on the structural requirements for biological activity. The studies identified three compounds that show similar activities to DzNep. Two of these compounds show good pharmacokinetics and safety profiles. Attempts to correlate the observed synergistic apoptotic activities with measured S-adenosylhomocysteine hydrolase (SAHH) inhibitory activities suggest that the apoptotic activity of DzNep might not be directly due to its inhibition of SAHH.

Design, synthesis and biological evaluation of FLT3 covalent inhibitors with a resorcylic acid core.

A series of simplified ring-opened resorcylic acid lactone (RAL) derivatives were conveniently synthesized to target FLT3 and its mutants either irreversibly or reversibly. Our design of covalent FLT3 inhibitors is based on cis-enone RALs (e.g., L-783,277) that have a ß-resorcylic acid as the core structure. The designed compounds contain three types of Michael acceptors (acrylamide, vinylsulfonamide and maleimide) as potential covalent traps of a cysteine residue at the binding site of kinases. A variety of functional substitutions were also introduced to maximize the binding interactions. Biological evaluations revealed that compound 17, despite the presence of a highly reactive maleimide Michael acceptor, is a potent covalent FLT3 inhibitor which shows some specificity in cellular assays. On the other hand, compounds 2 and 6 containing acrylamide or vinylsulfonamide groups are reversible towards FLT3 binding, and are potent and selective inhibitors of mutant FLT3-ITD versus wt-FLT3. They also inhibit cell proliferation in FLT3-ITD expressing cell line MV-4-11 as compared to wt-FLT3 expressing cell line THP-1 and non-FLT3 cell lines (K562, HL60 and Hek-293T).

Rational design of resorcylic acid lactone analogues as covalent MNK1/2 kinase inhibitors by tuning the reactivity of an enamide Michael acceptor.

Recent biological and computational advances in drug design have led to renewed interest in targeted covalent inhibition as an efficient and practical approach for the development of new drugs. As part of our continuing efforts in the exploration of the therapeutic potential of resorcylic acid lactones (RALs), we report herein the design, synthesis, and biological evaluation of conveniently accessible RAL enamide analogues as novel covalent inhibitors of MAP kinase interacting kinases (MNKs). In this study, we have successfully demonstrated that the covalent binding ability of RAL enamides can be tuned by attaching an electron-withdrawing motif, such as an acyl group, to enhance its reactivity toward the cysteine residues at the MNK1/2 binding sites. We have also shown that ¹H NMR spectroscopy is a convenient and effective tool for screening the covalent binding activities of enamides using cysteamine as a mimic of the key cysteine residue in the enzyme, whereas mass spectrometric analysis confirms covalent modification of the kinases. Preliminary optimization of the initial hit led to the discovery of enamides with low micromolar activity in MNK assays. Cancer cell line assays have identified RAL enamides that inhibit the growth of cancer cells with similar potency to the natural product L-783,277.