2-aminothiazole as a novel kinase inhibitor template. Structure-activity relationship studies toward the discovery of N-(2-chloro-6-methylphenyl)-2-[[6-[4-(2-hydroxyethyl)-1- piperazinyl)]-2-methyl-4-pyrimidinyl]amino)]-1,3-thiazole-5-carboxamide (dasatinib, BMS-354825) as a potent pan-Src kinase inhibitor

Transcriptional survey of alveolar macrophages in a murine model of chronic granulomatous inflammation reveals common themes with human sarcoidosis

Mohan A, Malur A, McPeek M, Barna BP, Schnapp LM, Thomassen MJ, Gharib SA. Transcriptional survey of alveolar macrophages in a murine model of chronic granulomatous inflammation reveals common themes with human sarcoidosis. Am J Physiol Lung Cell Mol Physiol 314: L617-L625, 2018. First published December 6, 2017; doi: 10.1152/ajplung.00289.2017 . To advance our understanding of the pathobiology of sarcoidosis, we developed a multiwall carbon nanotube (MWCNT)-based murine model that shows marked histological and inflammatory signal similarities to this disease. In this study, we compared the alveolar macrophage transcriptional signatures of our animal model with human sarcoidosis to identify overlapping molecular programs. Whole genome microarrays were used to assess gene expression of alveolar macrophages in six MWCNT-exposed and six control animals. The results were compared with the transcriptional profiles of alveolar immune cells in 15 sarcoidosis patients and 12 healthy humans. Rigorous statistical methods were used to identify differentially expressed genes. To better elucidate activated pathways, integrated network and gene set enrichment analysis (GSEA) was performed. We identified over 1,000 differentially expressed between control and MWCNT mice. Gene ontology functional analysis showed overrepresentation of processes primarily involved in immunity and inflammation in MCWNT mice. Applying GSEA to both mouse and human samples revealed upregulation of 92 gene sets in MWCNT mice and 142 gene sets in sarcoidosis patients. Commonly activated pathways in both MWCNT mice and sarcoidosis included adaptive immunity, T-cell signaling, IL-12/IL-17 signaling, and oxidative phosphorylation. Differences in gene set enrichment between MWCNT mice and sarcoidosis patients were also observed. We applied network analysis to differentially expressed genes common between the MWCNT model and sarcoidosis to identify key drivers of disease. In conclusion, an integrated network and transcriptomics approach revealed substantial functional similarities between a murine model and human sarcoidosis particularly with respect to activation of immune-specific pathways.

Target-similarity search using Plasmodium falciparum proteome identifies approved drugs with anti-malarial activity and their possible targets

Malaria causes about half a million deaths annually, with Plasmodium falciparum being responsible for 90% of all the cases. Recent reports on artemisinin resistance in Southeast Asia warrant urgent discovery of novel drugs for the treatment of malaria. However, most bioactive compounds fail to progress to treatments due to safety concerns. Drug repositioning offers an alternative strategy where drugs that have already been approved as safe for other diseases could be used to treat malaria. This study screened approved drugs for antimalarial activity using an in silico chemogenomics approach prior to in vitro verification. All the P. falciparum proteins sequences available in NCBI RefSeq were mined and used to perform a similarity search against DrugBank, TTD and STITCH databases to identify similar putative drug targets. Druggability indices of the potential P. falciparum drug targets were obtained from TDR targets database. Functional amino acid residues of the drug targets were determined using ConSurf server which was used to fine tune the similarity search. This study predicted 133 approved drugs that could target 34 P. falciparum proteins. A literature search done at PubMed and Google Scholar showed 105 out of the 133 drugs to have been previously tested against malaria, with most showing activity. For further validation, drug susceptibility assays using SYBR Green I method were done on a representative group of 10 predicted drugs, eight of which did show activity against P. falciparum 3D7 clone. Seven had IC50 values ranging from 1 μM to 50 μM. This study also suggests drug-target association and hence possible mechanisms of action of drugs that did show antiplasmodial activity. The study results validate the use of proteome-wide target similarity approach in identifying approved drugs with activity against P. falciparum and could be adapted for other pathogens.

Chemoproteomics-Aided Medicinal Chemistry for the Discovery of EPHA2 Inhibitors

The receptor tyrosine kinase EPHA2 has gained attention as a therapeutic drug target for cancer and infectious diseases. However, EPHA2 research and EPHA2-based therapies have been hampered by the lack of selective small-molecule inhibitors. Herein we report the synthesis and evaluation of dedicated EPHA2 inhibitors based on the clinical BCR-ABL/SRC inhibitor dasatinib as a lead structure. We designed hybrid structures of dasatinib and the previously known EPHA2 binders CHEMBL249097, PD-173955, and a known EPHB4 inhibitor in order to exploit both the ATP pocket entrance as well as the ribose pocket as binding epitopes in the kinase EPHA2. Medicinal chemistry and inhibitor design were guided by a chemical proteomics approach, allowing early selectivity profiling of the newly synthesized inhibitor candidates. Concomitant protein crystallography of 17 inhibitor co-crystals delivered detailed insight into the atomic interactions that underlie the structure-affinity relationship. Finally, the anti-proliferative effect of the inhibitor candidates was confirmed in the glioblastoma cell line SF-268. In this work, we thus discovered a novel EPHA2 inhibitor candidate that features an improved selectivity profile while maintaining potency against EPHA2 and anticancer activity in SF-268 cells.

Therapeutic immune monitoring of CD4+CD25+ T cells in chronic myeloid leukemia patients treated with tyrosine kinase inhibitors

Tyrosine kinase inhibitors (TKIs), including imatinib, dasatinib and nilotinib, are effective forms of therapy for various types of solid cancers and Philadelphia chromosome-positive (Ph⁺) chronic myeloid leukemia. A number of TKIs have been known to have strong effects on T cells, particularly cluster of differentiation (CD) 4⁺CD25⁺ T cells, also known as regulatory T cells (Tregs). There is currently a deficit in the available clinical data regarding this area of study. In the present study, a total of 108 peripheral blood samples were collected from patients with chronic myeloid leukemia (CML) at diagnosis (n=31), and at 3 and 6 months following treatment with TKI [imatinib (n=12), dasatinib (n=11) and nilotinib groups (n=8)] and healthy controls (n=15). Peripheral blood mononuclear cells were collected from the patients prior to and following TKI treatment. The subtype and number of T lymphocytes in patients and healthy donors were analyzed using flow cytometry. Additionally, flow cytometry and ELISA were used to detect the proliferation and suppression of Tregs. Expression of cytokines and other molecules [forkhead box P3 (FOXP3), glucocorticoid-induced tumor necrosis factor receptor (GITR) and cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4)] were also analyzed at 3 and 6 months following treatment with TKIs. It was indicated that, at diagnosis, a similar number of lymphocytes were detected in patients and control. However, following treatment with a TKI, the number of total T cells, Tregs, CD4⁺ T and CD8⁺ T cells decreased to various degrees in patients. Furthermore, the decrease in the number of Tregs was more significant with time. Although treatment with imatinib, dasatinib and nilotinib demonstrated similar inhibitory effects on the quantity of Tregs in vivo, the TKIs exhibited differential effects on the function of Tregs in vitro. Proliferation, suppression and expression of cytokines [interleukin (IL)-4, IL-10 and transforming growth factor (TGF)-β] and molecules (FOXP3, GITR and CTLA-4) decreased significantly in treatment groups with imatinib and dasatinib. The decrease was not significant in the nilotinib treatment group. Imatinib and dasatinib may exert more marked inhibitory roles compared with nilotinib on regulating the number and function of Tregs. These results suggest that personalized treatment and follow-up of CML patients during TKI treatment, particularly for those who received post-transplant TKI treatment may be beneficial.

The Multi-kinase Inhibitor Debio 0617B Reduces Maintenance and Self-renewal of Primary Human AML CD34+ Stem/Progenitor Cells

Acute myelogenous leukemia (AML) is initiated and maintained by leukemia stem cells (LSC). LSCs are therapy-resistant, cause relapse, and represent a major obstacle for the cure of AML. Resistance to therapy is often mediated by aberrant tyrosine kinase (TK) activation. These TKs primarily activate downstream signaling via STAT3/STAT5. In this study, we analyzed the potential to therapeutically target aberrant TK signaling and to eliminate LSCs via the multi-TK inhibitor Debio 0617B. Debio 0617B has a unique profile targeting key kinases upstream of STAT3/STAT5 signaling such as JAK, SRC, ABL, and class III/V receptor TKs. We demonstrate that expression of phospho-STAT3 (pSTAT3) in AML blasts is an independent prognostic factor for overall survival. Furthermore, phospho-STAT5 (pSTAT5) signaling is increased in primary CD34⁺ AML stem/progenitors. STAT3/STAT5 activation depends on tyrosine phosphorylation, mediated by several upstream TKs. Inhibition of single upstream TKs did not eliminate LSCs. In contrast, the multi-TK inhibitor Debio 0617B reduced maintenance and self-renewal of primary human AML CD34⁺ stem/progenitor cells in vitro and in xenotransplantation experiments resulting in long-term elimination of human LSCs and leukemia. Therefore, inhibition of multiple TKs upstream of STAT3/5 may result in sustained therapeutic efficacy of targeted therapy in AML and prevent relapses. Mol Cancer Ther; 16(8); 1497-510. ©2017 AACR.

Broad-Spectrum Kinase Profiling in Live Cells with Lysine-Targeted Sulfonyl Fluoride Probes

Protein kinases comprise a large family of structurally related enzymes. A major goal in kinase-inhibitor development is to selectively engage the desired kinase while avoiding myriad off-target kinases. However, quantifying inhibitor interactions with multiple endogenous kinases in live cells remains an unmet challenge. Here, we report the design of sulfonyl fluoride probes that covalently label a broad swath of the intracellular kinome with high efficiency. Protein crystallography and mass spectrometry confirmed a chemoselective reaction between the sulfonyl fluoride and a conserved lysine in the ATP binding site. Optimized probe 2 (XO44) covalently modified up to 133 endogenous kinases, efficiently competing with high intracellular concentrations of ATP. We employed probe 2 and label-free mass spectrometry to quantify intracellular kinase engagement by the approved drug, dasatinib. The data revealed saturable dasatinib binding to a small subset of kinase targets at clinically relevant concentrations, highlighting the utility of lysine-targeted sulfonyl fluoride probes in demanding chemoproteomic applications.

Casitas B-cell lymphoma (Cbl) proteins protect mammary epithelial cells from proteotoxicity of active c-Src accumulation

Casitas B-cell lymphoma (Cbl) family ubiquitin ligases negatively regulate tyrosine kinase-dependent signal transduction by promoting degradation of active kinases. We and others previously reported that loss of Cbl functions caused hyperproliferation in lymphoid and hematopoietic systems. Unexpectedly, Cbl deletion in Cbl-b-null, Cbl-c-null primary mouse mammary epithelial cells (MECs) (Cbl triple-deficiency) induced rapid cell death despite enhanced MAP kinase and AKT activation. Acute Cbl triple-deficiency elicited distinct transcriptional and biochemical responses with partial overlap with previously described cellular reactions to unfolded proteins and oxidative stress. Although the levels of reactive oxygen species were comparable, detergent-insoluble protein aggregates containing phosphorylated c-Src accumulated in Cbl triple-deficient MECs. Treatment with a broad-spectrum kinase inhibitor dasatinib blocked protein aggregate accumulation and restored in vitro organoid formation. This effect is most likely mediated through c-Src because Cbl triple-deficient MECs were able to form organoids upon shRNA-mediated c-Src knockdown. Taking these data together, the present study demonstrates that Cbl family proteins are required to protect MECs from proteotoxic stress-induced cell death by promoting turnover of active c-Src.

New bithiazolyl hydrazones: Novel synthesis, characterization and antitubercular evaluation

New bithiazolyl hydrazones (6a-l) have been first time synthesized by carrying novel one pot cyclocondensation of 5-acyl thiazoles (1a-b), thiosemicarbazide (2) and substituted phenacyl chlorides (4a-f) in freshly prepared ionic liquid, diisopropyl ethyl ammonium acetate (DIPEAc) at room temperature. The newly synthesized compounds have been evaluated for their antitubercular activity and the compounds 3b, 6a, 6b, 6d, 6e, 6f, 6g, and 6l have displayed noticeable antitubercular activity compared to Rifampicin with tolerable cytotoxicity. All these compounds were also screened for their antibacterial activity and found that, compounds 6j and 6k have exhibited a very good antibacterial activity. Molecular docking study has shown better harmony with the evaluation trend shown by these compounds under in vitro antitubercular screening.

From Lead to Drug Candidate: Optimization of 3-(Phenylethynyl)-1H-pyrazolo[3,4-d]pyrimidin-4-amine Derivatives as Agents for the Treatment of Triple Negative Breast Cancer

Herein we report the sophisticated process of structural optimization toward a previously disclosed Src inhibitor, compound 1, which showed high potency in the treatment of triple negative breast cancer (TNBC) both in vitro and in vivo but had considerable toxicity. A series of 3-(phenylethynyl)-1H-pyrazolo[3,4-d]pyrimidin-4-amine derivatives were synthesized. In vitro cell-based phenotypic screening together with in vivo assays and structure-activity relationship (SAR) studies finally led to the discovery of N-(3-((4-amino-1-(trans-4-hydroxycyclohexyl)-1H-pyrazolo[3,4-d]pyrimidin-3-yl)ethynyl)-4-methylphenyl)-4-methyl-3-(trifluoromethyl)benzamide (13an). 13an is a multikinase inhibitor, which potently inhibited Src (IC₅₀ = 0.003 μM), KDR (IC₅₀ = 0.032 μM), and several kinases involved in the MAPK signal transduction. This compound showed potent anti-TNBC activities both in vitro and in vivo, and good pharmacokinetic properties and low toxicity. Mechanisms of action of anti-TNBC were also investigated. Collectively, the data obtained in this study indicate that 13an could be a promising drug candidate for the treatment of TNBC and hence merits further studies.

c-Abl Inhibitors Enable Insights into the Pathophysiology and Neuroprotection in Parkinson's Disease

Parkinson’s disease (PD) is a progressive neurodegenerative disorder causing movement disabilities and several non-motor symptoms in afflicted patients. Recent studies in animal models of PD and analyses of brain specimen from PD patients revealed an increase in the level and activity of the non-receptor tyrosine kinase Abelson (c-Abl) in dopaminergic neurons with phosphorylation of protein substrates, such as α-synuclein and the E3 ubiquitin ligase, Parkin. Most significantly inhibition of c-Abl kinase activity by small molecular compounds used in the clinic to treat human leukemia have shown promising neuroprotective effects in cell and animal models of PD. This has raised hope that similar beneficial outcome may also be observed in the treatment of PD patients by using c-Abl inhibitors. Here we highlight the background for the current optimism, reviewing c-Abl and its relationship to pathophysiological pathways prevailing in PD, as well as discussing issues related to the pharmacology and safety of current c-Abl inhibitors. Clearly more rigorously controlled and well-designed trials are needed before the c-Abl inhibitors can be used in the neuroclinic to possibly benefit an increasing number of PD patients.

Chronic myeloid leukemia among patients with a history of prior malignancies: A tale of dual survivorship

BACKGROUND

Some patients with chronic myeloid leukemia (CML) have a history of previous malignancies. To the authors' knowledge, outcomes for CML diagnosed in these patients have not been well described. The current study was conducted to determine the outcome of patients with CML and a history of prior malignancies.

METHODS

The current study included patients who were enrolled in clinical trials of tyrosine kinase inhibitors as initial therapy for CML in chronic phase from July 2000 to January 2014.

RESULTS

Of the 630 patients with CML who were treated with frontline tyrosine kinase inhibitors, 626 had a known prior malignancy status. Of these, 45 patients (7%) had a prior malignancy other than nonmelanoma skin cancer whereas 17 patients (3%) had a history of nonmelanoma skin cancers alone. Characteristics of CML were similar between the patients with no prior malignancy, those with a prior malignancy, and those with nonmelanoma skin cancer. Patients with a prior malignancy were found to have an older median age compared with the other 2 groups. The most common prior malignancies were nonmelanoma skin cancer in 20 patients, breast cancer in 11 patients, melanoma in 7 patients, prostate cancer in 6 patients, and colorectal cancer in 5 patients. With regard to CML, the event-free survival, transformation-free survival, and failure-free survival rates were found to be similar between the groups. There was a statistically significantly decreased survival in the group with a prior malignancy versus the group with no prior malignancy versus the group with nonmelanoma skin cancer. In a multivariate analysis, advanced age and an elevated creatinine level were found to be associated with worse survival after a diagnosis of CML.

CONCLUSIONS

Patients with CML with a history of prior malignancies appear to have the same excellent outcome as patients with no prior malignancies. In the few instances in which concomitant therapy for other malignancies was required during therapy with tyrosine kinase inhibitors, this was able to be accomplished without significant toxicity. Cancer 2017;123:609-616. © 2016 American Cancer Society.

Synthesis and biological evaluation of novel dasatinib analogues as potent DDR1 and DDR2 kinase inhibitors

Novel dasatinib analogues as DDR1 and DDR2 inhibitors were designed and synthesized. The synthesized compounds were screened for DDR1 and DDR2 kinase inhibitory and cancer cell proliferation inhibitory activities. Some of the compounds showed the potent inhibitory activities against both DDR1 and DDR2, as well as anticancer activity in low nanomolar range against K562 cell line; especially, compound 3j demonstrated significantly better inhibitory potency than the parental dasatinib against both DDRs and also demonstrated the potent inhibitory activity against K562 cell lines (IC₅₀ values of 2.26±0.46 nm for DDR1, 7.04±2.90 nm for DDR2, and 0.125±0.017 nm for K562 cell line).

In vivo effective dibenzo[b,d]furan-1-yl-thiazoles as novel PDE-4 inhibitors

Herein we report the synthesis, PDE-4B and TNF-α inhibitory activities of a few dibenzo[b,d]furan-1-yl-thiazole derivatives. The hydroxycyclohexanol amide derivatives 14, 18, 24, 29, 31 and 33 exhibited promising in vitro PDE-4B and TNF-α inhibitory activities. Compound 24 showed good systemic availability in preclinical animal models and was also found to be non-toxic (exploratory mutagenicity test). Further it exhibited promising results in in vivo asthma/COPD and Uveitis models.

CagA Phosphorylation in Helicobacter pylori-Infected B Cells Is Mediated by the Nonreceptor Tyrosine Kinases of the Src and Abl Families

CagA is one of the most important virulence factors of the human pathogen Helicobacter pylori. CagA expression can be associated with the induction of severe gastric disorders such as gastritis, ulceration, gastric cancer, or mucosa-associated lymphoid tissue (MALT) lymphoma. After translocation through a type IV secretion system into epithelial cells, CagA is tyrosine phosphorylated by kinases of the Src and Abl families, leading to drastic cell elongation and motility. While the functional role of CagA in epithelial cells is well investigated, knowledge about CagA phosphorylation and its associated signal transduction pathways in B cells is only marginal. Here, we established the B cell line MEC1 derived from a B cell chronic lymphocytic leukemia (B-CLL) patient as a new infection model to study the signal transduction in B cells controlled by H. pylori. We observed that CagA was rapidly injected, strongly tyrosine phosphorylated, and cleaved into a 100-kDa N-terminal and a 40-kDa C-terminal fragment. To identify upstream signal transduction pathways of CagA phosphorylation in MEC1 cells, pharmacological inhibitors were employed to specifically target Src and Abl kinases. We observed that CagA phosphorylation was strongly inhibited upon treatment with an Src inhibitor and slightly diminished when the Abl kinase inhibitor imatinib mesylate (Gleevec) was applied. The addition of dasatinib to block c-Abl and Src kinases led to a complete loss of CagA phosphorylation. In conclusion, these results demonstrate an important role for Src and Abl tyrosine kinases in CagA phosphorylation in B cells, which represent druggable targets in H. pylori-mediated gastric MALT lymphoma.

Dehydrozingerone Inspired Styryl Hydrazine Thiazole Hybrids as Promising Class of Antimycobacterial Agents

Series of styryl hydrazine thiazole hybrids inspired from dehydrozingerone (DZG) scaffold were designed and synthesized by molecular hybridization approach. In vitro antimycobacterial activity of synthesized compounds was evaluated against Mycobacterium tuberculosis H37Rv strain. Among the series, compound 6o exhibited significant activity (MIC = 1.5 μM; IC50 = 0.48 μM) along with bactericidal (MBC = 12 μM) and intracellular antimycobacterial activities (IC50 = <0.098 μM). Furthermore, 6o displayed prominent antimycobacterial activity under hypoxic (MIC = 46 μM) and normal oxygen (MIC = 0.28 μM) conditions along with antimycobacterial efficiency against isoniazid (MIC = 3.2 μM for INH-R1; 1.5 μM for INH-R2) and rifampicin (MIC = 2.2 μM for RIF-R1; 6.3 μM for RIF-R2) resistant strains of Mtb. Presence of electron donating groups on the phenyl ring of thiazole moiety had positive correlation for biological activity, suggesting the importance of molecular hybridization approach for the development of newer DZG clubbed hydrazine thiazole hybrids as potential antimycobacterial agents.

Synthesis and antitubercular activity of new 1,3,4-oxadiazoles bearing pyridyl and thiazolyl scaffolds

In search of more potent and safe new antitubercular agents, here new 2-pyridinyl substituted thiazolyl-5-aryl-1,3,4-oxadiazoles (6a-o), have been designed and synthesized using thionicotinamide as a starting, following novel multistep synthetic route. An intermediate, pyridinyl substituted thiazolyl acid hydrazide (4) when condensed with benzoic acids/nicotinic acids (5a-o) in the presence of silica supported POCl3 yielded better to excellent yields of the title compounds. All the synthesized compounds (6a-o) and intermediate acid hydrazide (4) have been screened for their in vitro antitubercular activity against Mycobacterium tuberculosis H37Ra (MTB) and Mycobacterium bovis BCG. Amongst them, 6f, 6j, 6l and 6o have revealed promising activity against M. bovis BCG at concentrations less than 3μg/mL. These compounds have shown low cytotoxicity (CC50: >100μg/mL) towards four human cancer cell lines. Molecular docking study has also been performed against mycobacterial enoyl reductase (InhA) enzyme to gain an insight into the binding modes of these molecules and recorded good binding affinity. The ADME properties the title products have also been analyzed.

Identification of KPNB1 as a Cellular Target of Aminothiazole Derivatives with Anticancer Activity

We found that aminothiazole derivative (E)-N-(5-benzylthiazol-2-yl)-3-(furan-2-yl)acrylamide (1) has strong anticancer activity, and undertook proteomics approaches to identify the target protein of compound 1, importin β1 (KPNB1). A competitive binding assay using fluorescein-labeled 1 showed that 1 has strong binding affinity for KPNB1 (Kd : ∼20 nm). Furthermore, through western blotting assays for KPNB1, KPNA2, EGFR, ErbB2, and STAT3, we confirmed that 1 has inhibitory effects on the importin pathway. KPBN1 appears to be overexpressed in several cancer cells, and siRNA-induced inhibition of KPNB1 shows significant inhibition of cancer cell proliferation, while leaving non-cancerous cells unaffected. Therefore, compound 1 is a promising new lead for the development of KPNB1-targeted anticancer agents. Fluorescein-labeled 1 could be a useful quantitative probe for the development of novel KPNB1 inhibitors.

Synthesis and Evaluation of the 2-Aminothiazoles as Anti-Tubercular Agents

The 2-aminothiazole series has anti-bacterial activity against the important global pathogen Mycobacterium tuberculosis. We explored the nature of the activity by designing and synthesizing a large number of analogs and testing these for activity against M. tuberculosis, as well as eukaryotic cells. We determined that the C-2 position of the thiazole can accommodate a range of lipophilic substitutions, while both the C-4 position and the thiazole core are sensitive to change. The series has good activity against M. tuberculosis growth with sub-micromolar minimum inhibitory concentrations being achieved. A representative analog was selective for mycobacterial species over other bacteria and was rapidly bactericidal against replicating M. tuberculosis. The mode of action does not appear to involve iron chelation. We conclude that this series has potential for further development as novel anti-tubercular agents.

Synthesis and anticonvulsant activities of novel 2-(cyclopentylmethylene)hydrazinyl-1,3-thiazoles in mouse models of seizures

Synthesis, characterization and investigation of in vivo anticonvulsant activities of 13 novel cyclopentanecarbaldehyde-based 2,4-disubstituted 1,3-thiazoles are presented. Their structures were determined using (1)H and (13)C NMR, FAB(+)-MS, HRMS and elemental analyses. The results of anticonvulsant screening reveal that seven intraperitoneally administered compounds: 3a, 3b, 3d, 3e, 3f, 3k and 3m containing F-, Cl-, Br-, CF3-, CH3- and adamantyl substituents demonstrated significant anticonvulsant activity in the pentylenetetrazole model with median effective doses (ED50) ≤ 20 mg/kg, respectively, which was approximately seven-fold lower than that reported for the reference drug, ethosuximide. Noteworthy, none of these compounds impaired animals' motor skills in the rotarod test.

IL-7 Induces SAMHD1 Phosphorylation in CD4+ T Lymphocytes, Improving Early Steps of HIV-1 Life Cycle

HIV-1 post-integration latency in CD4+ lymphocytes is responsible for viral persistence despite treatment, but mechanisms involved in the establishment of latent viral reservoirs are not fully understood. We determined that both interleukin 2 (IL-2) and IL-7 induced SAMHD1 phosphorylation in T592, abrogating its antiviral activity. However, IL-7 caused a much more profound stimulatory effect on HIV-1 reverse transcription and integration than IL-2 that required chemokine co-stimulation. Both cytokines barely induced transcription due to low NF-κB induction, favoring the establishment of latent reservoirs. Effect of IL-7 on SAMHD1 phosphorylation was confirmed in IL-7-treated patients (ACTG 5214 study). Dasatinib—a tyrosine-kinase inhibitor—blocked SAMHD1 phosphorylation induced by IL-2 and IL-7 and restored HIV-1 restriction. We propose that γc-cytokines play a major role in the reservoir establishment not only by driving homeostatic proliferation but also by increasing susceptibility of CD4+ lymphocytes to HIV-1 infection through SAMHD1 inactivation.

Improvement of pyrazolo[3,4-d]pyrimidines pharmacokinetic properties: nanosystem approaches for drug delivery

Pyrazolo[3,4-d]pyrimidines are a class of compounds with a good activity against several cancer cell lines. Despite the promising anticancer activity, these molecules showed a poor aqueous solubility. This issue could threat the future development of pyrazolo[3,4-d]pyrimidines as clinical drug candidates. With the aim of improving their solubility profile and consequently their pharmacokinetic properties, we have chosen four compounds (1–4) on the base of their anti-neuroblastoma activity and we have developed albumin nanoparticles and liposomes for the selected candidates. Albumin nanoparticles and liposomes were prepared and characterized regarding size and ζ-potential distribution, polidispersity index, entrapment efficiency and activity against SH-SY5Y human neuroblastoma cell line. The most promising nanosystem, namely LP-2, was chosen to perform further studies: confocal microscopy, stability and drug release in physiological conditions, and biodistribution. Altogether, the obtained data strongly indicate that the encapsulation of pyrazolo[3,4-d]pyrimidines in liposomes represent an effective method to overcome the poor water solubility.

Design strategies, structure activity relationship and mechanistic insights for purines as kinase inhibitors

Kinases control a diverse set of cellular processes comprising of reversible phosphorylation of proteins. Protein kinases play a pivotal role in human tumor cell proliferation, migration and survival of neoplasia. In the recent past, purine based molecules have emerged as significantly potent kinase inhibitors. In view of their promising potential for the inhibition of kinases, this review article focuses on purines which have progressed as kinase inhibitors during the last five years. A detailed account of the design strategies employed for the synthesis of purine analogs exerting inhibitory effects on diverse kinases has been presented. Apart from presenting the design strategies, the article also highlights the structure activity relationship along with mechanistic insights revealed during the biological evaluation of the purine analogs for kinase inhibition. The interactions with the amino acid residues responsible for kinase inhibitory potential of purine based molecules have also been discussed. In this assemblage, purine based protein kinase inhibitors patented in the past have also been summarized in the tabular form. This compilation will be of great interest for the researchers working in the area of protein kinase inhibitors.

The exploration of network motifs as potential drug targets from post-translational regulatory networks

Phosphorylation and proteolysis are among the most common post-translational modifications (PTMs), and play critical roles in various biological processes. More recent discoveries imply that the crosstalks between these two PTMs are involved in many diseases. In this work, we construct a post-translational regulatory network (PTRN) consists of phosphorylation and proteolysis processes, which enables us to investigate the regulatory interplays between these two PTMs. With the PTRN, we identify some functional network motifs that are significantly enriched with drug targets, some of which are further found to contain multiple proteins targeted by combinatorial drugs. These findings imply that the network motifs may be used to predict targets when designing new drugs. Inspired by this, we propose a novel computational approach called NetTar for predicting drug targets using the identified network motifs. Benchmarking results on real data indicate that our approach can be used for accurate prediction of novel proteins targeted by known drugs.

Dasatinib inhibits HIV-1 replication through the interference of SAMHD1 phosphorylation in CD4+ T cells

Massive activation of infected CD4+ T cells during acute HIV-1 infection leads to reservoir seeding and T-cell destruction. During T-cell activation, the antiviral effect of the innate factor SAMHD1 is neutralized through phosphorylation at T592, allowing HIV-1 infection. Dasatinib, a tyrosine kinase inhibitor currently used for treating chronic myeloid leukemia, has been described to control HIV-1 replication through its negative effect on T-cell proliferation and viral entry. We demonstrate that Dasatinib can actually interfere with SAMHD1 phosphorylation in human peripheral blood lymphocytes, preserving its antiviral activity against HIV-1. Dasatinib prevented SAMHD1 phosphorylation in vitro and ex vivo, impairing HIV-1 reverse transcription and proviral integration. This was the major mechanism of action because the presence of Vpx, which degrades SAMHD1, in HIV-1 virions impeded the inhibitory effect of Dasatinib on HIV-1 replication. In fact, infection with VSV-pseudotyped HIV-1 virions and fusion of BlaM-Vpr-containing HIV-1 viruses with activated PBMCs in the presence of Dasatinib suggested that Dasatinib was not acting at fusion level. Finally, PBMCs from patients on chronic treatment with Dasatinib showed a lower level of SAMHD1 phosphorylation in response to activating stimuli and low susceptibility to HIV-1 infection ex vivo. Consequently, Dasatinib is a compound currently used in clinic that preserves the antiviral function of SAMHD1. Using Dasatinib as adjuvant of antiretroviral therapy during early primary HIV-1 infection would contribute to reduce viral replication and spread, prevent reservoir seeding, and preserve CD4 counts and CTL responses. These events would create a more favorable virologic and immunologic environment for future interventional studies aiming at HIV-1 eradication.

Screening for covalent inhibitors using DNA-display of small molecule libraries functionalized with cysteine reactive moieties

Discriminating between non-covalent and covalent inhibitors with SDS wash in microarray-based screen.

An optimized approach in the synthesis of imatinib intermediates and analogues

We revisited the classical synthetic procedure for imatinib synthesis providing an improved and optimized approach in the preparation of a series of new imatinib analogues.

FAIMS and Phosphoproteomics of Fibroblast Growth Factor Signaling: Enhanced Identification of Multiply Phosphorylated Peptides

We have applied liquid chromatography high-field asymmetric waveform ion mobility spectrometry tandem mass spectrometry (LC-FAIMS-MS/MS) and liquid chromatography tandem mass spectrometry (LC-MS/MS) to the investigation of site-specific phosphorylation in fibroblast growth factor (FGF) signaling. We have combined a SILAC approach with chemical inhibition by SU5402 (an FGF receptor tyrosine kinase inhibitor) and dasatinib (a Src family kinase inhibitor). The results show that incorporation of FAIMS within the workflow results in (a) an increase in the relative proportion of phosphothreonine and phosphotyrosine sites identified, (b) an increase in phosphopeptide identifications from precursors with charge states ≥ +3 (with an associated increase in peptide length), and (c) an increase in the identification of multiply phosphorylated peptides. Approximately 20% of the phosphorylation sites identified via the FAIMS workflow had not been reported previously, and over 80% of those were from multiply phosphorylated peptides. Moreover, FAIMS provided access to a distinct set of phosphorylation sites regulated in response to SU5402 and dasatinib. The enhanced identification of multiply phosphorylated peptides was particularly striking in the case of sites regulated by SU5402. In addition to providing a compelling example of the complementarity of FAIMS in phosphoproteomics, the results provide a valuable resource of phosphorylation sites for further investigation of FGF signaling and trafficking.

Identification of Aminoimidazole and Aminothiazole Derivatives as Src Family Kinase Inhibitors

Src family kinases (SFKs) are a family of non-receptor tyrosine kinases (TKs) implicated in the regulation of many cellular processes. The aberrant activity of these TKs has been associated with the growth and progression of cancer. In particular, c-Src is overexpressed or hyperactivated in a variety of solid tumors and is most likely a strong promoting factor for the development of metastasis. Herein, the synthesis of new 4-aminoimidazole and 2-aminothiazole derivatives and their in vitro biological evaluation are described for their potential use as SFK inhibitors. Initially, 2-aminothiazole analogues of dasatinib and 4-aminoimidazole derivatives were synthesized and tested against the SFKs Src, Fyn, Lyn, and Yes. Five hits were identified as the most promising compounds, with Ki values in the range of 90-480 nm. A combination of molecular docking, homology modeling, and molecular dynamics were then used to investigate the possible binding mode of such compounds within the ATP binding site of the SFKs. Finally, the antiproliferative activities of the best candidates were evaluated against SH-SY5Y and K562 cell lines. Compound 3 b [2-(4-{2-methyl-6-[(5-phenylthiazol-2-yl)amino]pyrimidin-4-yl}piperazin-1-yl)ethanol] was found to be the most active inhibitor.

Dissecting fibrosis: therapeutic insights from the small-molecule toolbox

Fibrosis, which leads to progressive loss of tissue function and eventual organ failure, has been estimated to contribute to ~45% of deaths in the developed world, and so new therapeutics to modulate fibrosis are urgently needed. Major advances in our understanding of the mechanisms underlying pathological fibrosis are supporting the search for such therapeutics, and the recent approval of two anti-fibrotic drugs for idiopathic pulmonary fibrosis has demonstrated the tractability of this area for drug discovery. This Review examines the pharmacology and structural information for small molecules being evaluated for lung, liver, kidney and skin fibrosis. In particular, we discuss the insights gained from the use of these pharmacological tools, and how these entities can inform, and probe, emerging insights into disease mechanisms, including the potential for future drug combinations.

Characterization of Novel Src Family Kinase Inhibitors to Attenuate Microgliosis

Microgliosis is a major hallmark of Alzheimer's disease (AD) brain pathology. Aβ peptide is hypothesized to act as a stimulus for microglia leading to activation of non-receptor tyrosine kinases and subsequent secretion of pro-inflammatory cytokines. Therefore, the signaling pathways mediating microglial activation may be important therapeutic targets of anti-inflammatory therapy for AD. Four novel compounds were chosen after high throughput screening kinase activity assays determined them as potential Lyn kinase inhibitors. Their kinase inhibitory and anti-inflammatory effect on Aβ-stimulated activation was assessed using the murine microglial cell line, BV2. Cells were treated with the compounds to determine effects on active, phosphorylated levels of Src family kinases, Src and Lyn, as well as MAP kinases ERK, JNK and p38. Only one compound, LDDN-0003499, produced a dose dependent decrease in basal levels of active, phosphorylated Src and Lyn in the BV2 cells. LDDN-0003499 treatment also attenuated the Aβ-stimulated increase in active, phosphorylated levels of Lyn/Src and TNFα and IL-6 secretion. This study identifies a novel small molecule Src family tyrosine kinase inhibitor with anti-inflammatory effects in response to Aβ stimulation of microglia. Further in vitro/in vivo characterization of LDDN-0003499 as well as structural modification may provide a new tool for attenuating microglial-mediated brain inflammatory conditions such as that occurring in AD.

Fragment-Based Discovery of Potent and Selective DDR1/2 Inhibitors

The DDR1 and DDR2 receptor tyrosine kinases are activated by extracellular collagen and have been implicated in a number of human diseases including cancer. We performed a fragment-based screen against DDR1 and identified fragments that bound either at the hinge or in the back pocket associated with the DFG-out conformation of the kinase. Modeling based on crystal structures of potent kinase inhibitors facilitated the "back-to-front" design of potent DDR1/2 inhibitors that incorporated one of the DFG-out fragments. Further optimization led to low nanomolar, orally bioavailable inhibitors that were selective for DDR1 and DDR2. The inhibitors were shown to potently inhibit DDR2 activity in cells but in contrast to unselective inhibitors such as dasatinib, they did not inhibit proliferation of mutant DDR2 lung SCC cell lines.

A structural atlas of kinases inhibited by clinically approved drugs

The aberrant activation of protein kinases is associated with many human diseases, most notably cancer. Due to this link between kinase deregulation and disease progression, kinases are one of the most targeted protein families for small-molecule inhibition. Within the last 15 years, the U.S. Food and Drug Administration has approved over 20 small-molecule inhibitors of protein kinases for use in the clinic. These inhibitors target the kinase active site and represent the successful hurdling by medicinal chemists of the formidable challenge posed by the high similarity among the active sites of the approximately 500 human kinases. We review the conserved structural features of kinases that are important for inhibitor binding as well as for catalysis. Many clinically approved drugs elicit selectivity by exploiting subtle variation within the kinase active site. We highlight some of the crystallographic studies on the kinase-inhibitor complexes that have provided valuable guidance for the development of these drugs as well as for future drug design efforts.

Discovery of nitroaryl urea derivatives with antiproliferative properties

A series of urea derivatives bearing nitroaryl moiety has been synthesized and assayed for their potential antiproliferative activities. Some of the tested compounds displayed activity in RK33 laryngeal cancer cells and TE671 rhabdomyosarcoma cells while being generally less toxic to healthy HSF human fibroblasts cells. One compound was demonstrated to be a moderate CDK2 inhibitor with IC50 = 14.3 µM. Its structure was solved by an X-ray crystallography and molecular modelling was performed to determine structure-activity relationship. Obtained compounds constitute novel structures and generally demonstrated greater cytotoxicity in comparison to cisplatin. This study offers new structural motifs with potential for further development.

Thiophene and benzodioxole appended thiazolyl-pyrazoline compounds: Microwave assisted synthesis, antimicrobial and molecular docking studies

A novel series of thiophene and benzodioxole appended thiazolyl-pyrazoline derivatives have been designed, synthesized and evaluated against different bacteria and fungi. The antimicrobial activity of the synthesized compounds were screened using MIC method and were proved synthesized compounds 7o, 7r and 7t to show good antimicrobial activity against bacteria and fungi. In silico molecular docking studies revealed that all the synthesized molecules showed good binding energy toward the target receptor DNA topoisomerase IV, ranging from -10.42 to -11.66 kcal/mol.

Therapeutic effects of dasatinib in mouse model of multiple sclerosis

BACKGROUND

Experimental autoimmune encephalomyelitis (EAE) is a mouse model for multiple sclerosis (MS). EAE is mainly mediated by adaptive and innate immune responses that lead to an inflammatory demyelination and axonal damage. Dasatinib (Sprycel) is a selective protein tyrosine kinase inhibitor with immunomodulatory properties that abrogates multiple signal transduction pathways in immune cells. In the present research, our aim was to test the therapeutic efficacy of dasatinib in experimental model of MS.

METHODS

We performed EAE induction in female C57BL/6 mice by myelin oligodendrocyte glycoprotein(35-55) (MOG(35-55)) in Complete Freund's Adjuvant (CFA) emulsion, and used dasatinib for the treatment of EAE. During the course of study, clinical evaluation was assessed, and on day 21 post-immunization blood samples were taken from the heart of mice for tumor necrosis factor-alpha (TNF-α), nitric oxide (NO) and antioxidants capacity evaluation. The mice were sacrificed and brains and cerebellums of mice were removed for histological analysis. Also for in vitro analysis, we used C6 astrocytoma cell line to evaluate the inhibitory effects of dasatinib in cell proliferation and matrix metalloproteinase-2 (MMP-2) activity.

RESULTS

Our findings demonstrated that dasatinib had beneficial effects on EAE by lower incidence, attenuation in the severity and a delay in the onset of disease. The serum level of NO and TNF-α in dasatinib treated mice was significantly lower than control mice. In vitro, dasatinib inhibited cell proliferation and MMP-2 activity.

CONCLUSION

Dasatinib with its potential therapeutic effects and immunomodulatory properties may be recommended, after additional necessary tests and trials, for the treatment of MS.

Development of small molecules targeting the pseudokinase Her3

Her3 is a member of the human epidermal growth factor receptor (EGFR) tyrosine kinase family, and it is often either overexpressed or deregulated in many types of human cancer. Her3 has not been the subject of small-molecule inhibitor development because it is a pseudokinase and does not possess appreciable kinase activity. We recently reported on the development of the first selective irreversible Her3 ligand (TX1-85-1) that forms a covalent bond with cysteine 721 which is unique to Her3 among all kinases. We also developed a bi-functional compound (TX2-121-1) containing a hydrophobic adamantane moiety and the same warhead of TX1-85-1 that is capable of inhibiting Her3-dependent signaling and growth. Here we report on the structure-based medicinal chemistry effort that resulted in the discovery of these two compounds.

Recent applications of 1,3-thiazole core structure in the identification of new lead compounds and drug discovery

1,3-Thiazole is one of the most important scaffolds in heterocyclic chemistry and drug design and discovery. It is widely found in diverse pharmacologically active substances and in some naturally-occurring compounds. Thiazole is a versatile building-block for lead generation, and is easily access of diverse derivatives for subsequent lead optimization. In the recent years, many thiazole derivatives have been synthesized and subjected to varied biological activities. In this article we intended to review the most important biological effects of thiazole-based compounds and highlight their roles in new leads identification and drug discovery. This article is also intended to help researches for finding potential future directions on the development of more potent and specific analogs of thiazole-based compounds for various biological targets.