Substituted 5,7-diphenyl-pyrrolo[2,3d]pyrimidines: potent inhibitors of the tyrosine kinase c-Src

OCLI-023, a Novel Pyrimidine Compound, Suppresses Osteoclastogenesis In Vitro and Alveolar Bone Resorption In Vivo

An abnormal increase in osteoclast differentiation and activation results in various bone-resorptive diseases, including periodontitis, rheumatoid arthritis, and osteoporosis. Chemical compounds containing pyrimidine ring have been shown to regulate a variety of biological processes. Therefore, in order to identify an antiresorptive agent, we synthesized a series of pyrimidine ring-containing chemical compounds, and found that OCLI-023 suppressed the differentiation and activation of osteoclasts in vitro. OCLI-023 directly inhibited receptor activator of nuclear factor-κB ligand (RANKL)-induced differentiation of bone marrow macrophages into osteoclasts, without a cytotoxic response. OCLI-023 also downregulated the RANKL-induced mRNA expression of osteoclast markers as well as inhibited the formation of actin rings and resorption pits. OCLI-023 attenuated the RANKL-induced activation of c-Jun N-terminal kinase and nuclear factor kappa-light-chain-enhancer of activated B cell signaling pathways. In a mouse model of periodontitis, ligature induced an increase of distance between cementoenamel junction (CEJ) and alveolar bone crest (ABC) in the second molar, and OCLI-023 significantly reduced it. Histological analysis showed ligature-induced increase of osteoclast numbers was also significantly reduced by OCLI-023. These data demonstrated the inhibitory effect of OCLI-023 on osteoclast differentiation and activity of osteoclasts in vitro, as well as on ligature-induced bone loss in vivo, and OCLI-023 can be proposed as a novel anti-resorptive compound.

A multicomponent reaction of 2-aminoimidazoles: microwave-assisted synthesis of novel 5-aza-7-deaza-adenines

An efficient and highly selective multicomponent synthesis of 4-aminoimidazo[1,2-a]triazines, which are 5-aza-7-deaza-isosteres of adenine, was developed.

Development and experimental test of support vector machines virtual screening method for searching Src inhibitors from large compound libraries

BACKGROUND

Src plays various roles in tumour progression, invasion, metastasis, angiogenesis and survival. It is one of the multiple targets of multi-target kinase inhibitors in clinical uses and trials for the treatment of leukemia and other cancers. These successes and appearances of drug resistance in some patients have raised significant interest and efforts in discovering new Src inhibitors. Various in-silico methods have been used in some of these efforts. It is desirable to explore additional in-silico methods, particularly those capable of searching large compound libraries at high yields and reduced false-hit rates.

RESULTS

We evaluated support vector machines (SVM) as virtual screening tools for searching Src inhibitors from large compound libraries. SVM trained and tested by 1,703 inhibitors and 63,318 putative non-inhibitors correctly identified 93.53%~ 95.01% inhibitors and 99.81%~ 99.90% non-inhibitors in 5-fold cross validation studies. SVM trained by 1,703 inhibitors reported before 2011 and 63,318 putative non-inhibitors correctly identified 70.45% of the 44 inhibitors reported since 2011, and predicted as inhibitors 44,843 (0.33%) of 13.56M PubChem, 1,496 (0.89%) of 168 K MDDR, and 719 (7.73%) of 9,305 MDDR compounds similar to the known inhibitors.

CONCLUSIONS

SVM showed comparable yield and reduced false hit rates in searching large compound libraries compared to the similarity-based and other machine-learning VS methods developed from the same set of training compounds and molecular descriptors. We tested three virtual hits of the same novel scaffold from in-house chemical libraries not reported as Src inhibitor, one of which showed moderate activity. SVM may be potentially explored for searching Src inhibitors from large compound libraries at low false-hit rates.

The alternative TrkAIII splice variant targets the centrosome and promotes genetic instability

The hypoxia-regulated alternative TrkAIII splice variant expressed by human neuroblastomas exhibits oncogenic potential, driven by in-frame exon 6 and 7 alternative splicing, leading to omission of the receptor extracellular immunoglobulin C(1) domain and several N-glycosylation sites. Here, we show that the TrkAIII oncogene promotes genetic instability by interacting with and exhibiting catalytic activity at the centrosome. This function depends upon intracellular TrkAIII accumulation and spontaneous interphase-restricted activation, in cytoplasmic tyrosine kinase (tk) domain orientation, predominantly within structures that closely associate with the fully assembled endoplasmic reticulum intermediate compartment and Golgi network. This facilitates TrkAIII tk-mediated binding of gamma-tubulin, which is regulated by endogenous protein tyrosine phosphatases and geldanamycin-sensitive interaction with Hsp90, paving the way for TrkAIII recruitment to the centrosome. At the centrosome, TrkAIII differentially phosphorylates several centrosome-associated components, increases centrosome interaction with polo kinase 4, and decreases centrosome interaction with separase, the net results of which are centrosome amplification and increased genetic instability. The data characterize TrkAIII as a novel internal membrane-associated centrosome kinase, unveiling an important alternative mechanism to "classical" cell surface oncogenic receptor tk signaling through which stress-regulated alternative TrkAIII splicing influences the oncogenic process.

1,3-Disubstituted-imidazo[1,5-a]pyrazines as insulin-like growth-factor-I receptor (IGF-IR) inhibitors

A series of novel 8-amino-1,3-disubstituted-imidazo[1,5-a]pyrazines was designed and synthesized as IGF-IR inhibitors.

Multifocal angiostatic therapy: an update

Multifocal angiostatic therapy (MAT) is a strategy that seeks to impede cancer-induced angiogenesis by addressing multiple targets that regulate the angiogenic capacity of a cancer and/or the angiogenic responsiveness of endothelial cells, using measures that are preferentially, but not exclusively, nutraceutical. A prototype of such a regimen has been proposed previously, composed of green tea polyphenols, fish oil, selenium, and high-dose glycine, complementing a low-fat vegan diet, exercise training, and the copper-sequestering drug tetrathiomolybdate (TM). A review of more recent evidence suggests additional agents that could appropriately be included in this regimen and clarifies to some extent the mechanisms of action of its constituents. Diindolylmethane, a widely available crucifera-derived nutraceutical, has inhibited cancer growth in several mouse xenograft models; this effect may be largely attributable to an angiostatic action, as concentrations as low as 5 to 10 muM inhibit proliferation, migration, and tube-forming capacity of human endothelial cells in vitro, and a parenteral dose of 5 mg/kg markedly impairs matrigel angiogenesis in mice. Silymarin/silbinin, which has slowed the growth of human xenografts in a number of studies, suppresses the proliferation, migration, and tube-forming capacity of endothelial cells and inhibits vascular endothelial growth factor (VEGF) secretion by a range of human cancer cell lines, in concentrations that should be clinically feasible. The angiostatic activity of orally administered green tea now appears likely to reflect inhibition of the kinase activity of VEGFR-2. Glycine's angiostatic activity may be attributable to a hyperpolarizing effect on endothelial cells that decreases the activity of NADPH oxidase, now known to promote tyrosine kinase signaling in endothelial cells. The ability of TM to suppress cancer cell production of a range of angiogenic factors results at least in part from a down regulation of NF-kappaB activation. Dual-purpose molecular targets, whose inhibition could be expected to decrease the aggressiveness and chemoresistance of cancer cells while simultaneously impeding angiogenesis, include NF-kappaB, cox-2, c-Src, Stat3, and hsp90; drugs that can address these targets are now in development, and salicylates are notable for the fact that they can simultaneously inhibit NF-kappaB and cox-2. The potential complementary of the components of MAT should be assessed in nude mouse xenograft models.

A Combination of Docking/Dynamics Simulations and Pharmacophoric Modeling To Discover New Dual c-Src/Abl Kinase Inhibitors

A computational protocol was applied to identify molecular scaffolds untested toward the c-Src tyrosine kinase. A combination of docking and dynamics calculations allowed us to build three-dimensional models of the complexes between Src and several of its known inhibitors. Interactions most contributing to activity of the inhibitors, in terms of hydrogen bonds and hydrophobic contacts, were codified into pharmacophoric models that were in turn applied to perform a search of commercially available compounds within the Asinex database. As a result, we identified 1,3,4-thiadiazoles and pyrazolydine-3,5-diones showing inhibitory activity in the submicromolar range in a cell-free assay toward Src. Moreover, since several of the compounds used to generate pharmacophores were also known as Abl inhibitors, we tested the identified hits toward Abl tyrosine kinase, finding activity in the submicromolar range. Such biological data suggested that the computational protocol is an efficient tool for identifying new hits toward both Src and Abl.

Inhibition of protein kinase c-Src reduces the incidence of breast cancer metastases and increases survival in mice: implications for therapy

c-Src is a proto-oncogene, belonging to the nonreceptor protein kinases family, which plays a prominent role in carcinogenesis. In this study, we tested the hypothesis that c-Src could promote breast cancer metastasis acting on several cell types and that pharmacological disruption of its kinase activity could be beneficial for the treatment of metastases. Female BALB/c-nu/nu mice were subjected to intracardiac injection of the human breast cancer cells MDA-MB-231 (MDA-231), which induced prominent bone and visceral metastases. These were pharmacologically reduced by treatment with the c-Src inhibitor [7-{4-[2-(2-methoxy-ethylamino-ethoxy]-phenyl}-5-(3-methoxy-phenyl)-7H-pyrrolo[2,3-d]pyrimidin-4-ylamine] CGP76030 (100 mg/kg/day p.o.), resulting in decreased morbidity and lethality. Metastases were more severe in mice injected with MDA-231 cells stably transfected with wild-type c-Src (MDA-231-SrcWT), whereas transfection in injected cells of a c-Src kinase-dead dominant-negative construct (MDA-231-SrcDN) resulted in reduced morbidity, lethality, and incidence of metastases similar to the mice treated with the inhibitor. An analogous beneficial effect of c-Src inhibition was observed in subcutaneous and intratibial implanted tumors. In vitro, c-Src suppression reduced MDA-231 cell aggressiveness. It also impaired osteoclast bone resorption both directly and by reducing expression by osteoblasts of the osteoclastogenic cytokines interleukin-1beta and interleukin-6, whereas parathyroid hormone-related peptide was not implicated. c-Src was also modestly but consistently involved in the enhancement of endothelial cell proliferation in vitro and angiogenesis in vivo. In conclusion, we propose that c-Src disruption affects the metastatic process and thus is a therapeutic target for the treatment of breast cancer.

Crystal structures of active SRC kinase domain complexes

c-Src was the first proto-oncoprotein to be identified, and has become the focus of many drug discovery programs. Src structures of a major inactive form have shown how the protein kinase is rigidified by several interdomain interactions; active configurations of Src are generated by release from this "assembled" or "bundled" form. Despite the importance of Src as a drug target, there is relatively little structural information available regarding the presumably more flexible active forms. Here we report three crystal structures of a dimeric active c-Src kinase domain, in an apo and two ligand complexed forms, with resolutions ranging from 2.9A to 1.95A. The structures show how the kinase domain, in the absence of the rigidifying interdomain interactions of the inactivation state, adopts a more open and flexible conformation. The ATP site inhibitor CGP77675 binds to the protein kinase with canonical hinge hydrogen bonds and also to the c-Src specific threonine 340. In contrast to purvalanol B binding in CDK2, purvalanol A binds in c-Src with a conformational change in a more open ATP pocket.

Fast Small Molecule Similarity Searching with Multiple Alignment Profiles of Molecules Represented in One-Dimension

Multiple sequence alignment has proven to be a powerful method for creating protein and DNA sequence alignment profiles. These profiles of protein families are useful tools for identifying conserved motifs, such as the catalytic triad of the serine protease family or the seven transmembrane helices of the G-protein coupled receptor family. Ultimately, the understanding of the critical motifs within a family is useful for identifying new members of the family. Due to the complexity of protein-ligand recognition, no universally accepted method exists for clustering small molecules into families with the same or similar biological activity. A combination of the concept of multiple sequence alignment and the 1-dimensional molecular representation described earlier offers a new method for profiling sets of small molecules with the same biological activity. These small molecule profiles can isolate key commonalities within the set of bioactive compounds much like a multiple sequence alignment can isolate critical motifs within a protein family. The small molecule profiles then make useful tools for searching small molecule databases for new compounds with the same biological activity. The technique is demonstrated here using the human ether-a-go-go potassium channel and the kinase SRC.

3D-QSAR studies on c-Src kinase inhibitors and docking analyses of a potent dual kinase inhibitor of c-Src and c-Abl kinases

Three-dimensional quantitative structure-activity relationship (3D-QSAR) analyses were carried out on quinazoline, quinoline, and cyanoquinoline derivatives inhibiting c-Src kinase. Comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA) 3D-QSAR models were developed. The conventional r2 values for CoMFA and CoMSIA are 0.93 and 0.89, respectively. In addition, a homology model of c-Src kinase with the activation loop resembling the active conformation was constructed using the crystal structure of the kinase domain of Lck. The ATP binding pocket of the active form of c-Src is similar to that of the c-Abl kinase in which the activation loop resembles that of an active form. One of the potent c-Src and c-Abl dual kinase inhibitors (77 or SKI-606) was docked inside the active sites of both c-Src and c-Abl. The orientation and hydrogen bonding interactions of 77 are similar in both kinases. The results of 3D-QSAR analyses and structure based studies will be useful for the design of novel c-Src and c-Abl dual kinase inhibitors.

4-Anilino-7,8-dialkoxybenzo[g]quinoline-3-carbonitriles as Potent Src Kinase Inhibitors

It has been previously reported that appropriately substituted 4-anilinoquinoline-3-carbonitriles are potent inhibitors of Src kinase, with biological activity in vitro and in vivo. Structural modifications to these compounds have been explored, providing the 4-anilinobenzo[g]quinoline-3-carbonitriles as a series with enhanced Src inhibitory properties. The synthesis and structure-activity relationships of these 4-anilino-7,8-dialkoxybenzo[g]quinoline-3-carbonitriles are presented here. Analogues with cyclic basic amine groups attached via ethoxy linkages at the C-8 position were the most active in vitro, with subnanomolar IC50 values against Src kinase observed for a majority of the compounds synthesized. Compound 17d was more potent in vitro than the analogously substituted 4-anilinoquinoline-3-carbonitrile SKI-606, which is undergoing evaluation in clinical trials. The most potent analogue synthesized was 17a, with an IC50 of 0.15 nM against Src kinase and with an IC50 of 10 nM against Src-transformed fibroblasts. Molecular modeling studies provided a rationale for the exceptional activity observed for these compounds, with favorable van der Waals interactions playing the major role. Compound 17c was found to be highly selective for Src kinase when tested against a panel of other kinases, with modest selectivity versus the Src family kinases Lyn and Fyn. Following ip dosing at 50 mg/kg, analogues 17c and 17d were shown to have plasma levels that significantly exceeded the cellular IC50 values against Src-transformed fibroblasts. In an Src-transformed fibroblast xenograft model, both compounds exhibited a significant inhibition of tumor growth.

Targeting multiple signaling pathways as a strategy for managing prostate cancer: multifocal signal modulation therapy

The aberrant behavior of cancer reflects upregulation of certain oncogenic signaling pathways that promote proliferation, inhibit apoptosis, and enable the cancer to spread and evoke angiogenesis. Theoretically, it should be feasible to decrease the activity of these pathways-or increase the activity of pathways that oppose them-with noncytotoxic agents. Since multiple pathways are dysfunctional in most cancers, and cancers accumulate new oncogenic mutations as they progress, the greatest and most durable therapeutic benefit will likely be achieved with combination regimens that address several targets. Thus, a multifocal signal modulation therapy (MSMT) of cancer is proposed. This concept has already been documented by researchers who have shown that certain combinations of signal modulators-of limited utility when administered individually-can achieve dramatic suppression of tumor growth in rodent xenograft models. The present essay attempts to guide development of MSMTs for prostate cancer. Androgen ablation is a signal-modulating measure already in standard use in the management of delocalized prostate cancer. The additional molecular targets considered here include the type 1 insulin-like growth factor receptor, the epidermal growth factor receptor, mammalian target of rapamycin, NF-kappaB, hypoxia-inducible factor-1alpha, hsp90, cyclooxygenase-2, protein kinase A type I, vascular endothelial growth factor, 5-lipoxygenase, 12-lipoxygenase, angiotensin II receptor type 1, bradykinin receptor type 1, c-Src, interleukin-6, ras, MDM2, bcl-2/bclxL, vitamin D receptor, estrogen receptor-beta, and PPAR-. Various nutrients and phytochemicals suspected to have potential utility in prostate cancer prevention and therapy, but whose key molecular targets are still unknown, might reasonably be incorporated into MSMTs for prostate cancer; these include lycopene, selenium, green tea polyphenols, genistein, and silibinin. MSMTs can be developed systematically by testing various combinations of signal-modulating agents, in concentrations that can feasibly be achieved and maintained clinically, on human prostate cancer cell lines; combinations that appear promising can then be tested in xenograft models and, ultimately, in the clinic. Some signal modulators can increase response to cytotoxic drugs by upregulating effectors of apoptosis. When MSMTs fail to raise the spontaneous apoptosis rate sufficiently to achieve tumor stasis or regression, incorporation of appropriate cytotoxic agents into the regimen may improve the clinical outcome.

New pyrazolo[3,4-d]pyrimidines endowed with A431 antiproliferative activity and inhibitory properties of Src phosphorylation

New 4-aminopyrazolo[3,4-d]pyrimidines bearing various substituents at the position 1 and 6, were synthesized. The new compounds showed antiproliferative activity toward A431 cells, were found to be inhibitors of Src phosphorylation, and induced apoptotic cell death. In particular, 2h was a better inhibitor of Src phosphorylation than the reference compound PP2.

Kinomics-structural biology and chemogenomics of kinase inhibitors and targets

Classifying kinases based entirely on small molecule selectivity data is a new approach to drug discovery that allows scientists to understand relationships between targets. This approach combines the understanding of small molecules and targets, and thereby assists the researcher in finding new targets for existing molecules or understanding selectivity and polypharmacology of molecules in related targets. Currently, structural information is available for relatively few of the protein kinases encoded in the human genome (7% of the estimated 518); however, even the current knowledge base, when paired with structure-based design techniques, can assist in the identification and optimization of novel kinase inhibitors across the entire protein class. Chemogenomics attempts to combine genomic data, structural biological data, classical dendrograms, and selectivity data to explore, define, and classify the medicinally relevant kinase space. Exploitation of this information in the discovery of kinase inhibitors defines practical kinase chemogenomics (kinomics). In this paper, we review the available information on kinase targets and their inhibitors, and present the relationships between the various classification schema for kinase space. In particular, we present the first dendrogram of kinases based entirely on small molecule selectivity data. We find that the selectivity dendrogram differs from sequence-based clustering mostly in the higher-level groupings of the smaller clusters, and remains very comparable for closely homologous targets. Highly homologous kinases are, on average, inhibited comparably by small molecules. This observation, although intuitive, is very important to the process of target selection, as one would expect difficulty in achieving inhibitor selectivity for kinases that share high sequence identity.

Discovery of a new class of anilinoquinazoline inhibitors with high affinity and specificity for the tyrosine kinase domain of c-Src

Deregulated activity of the nonreceptor tyrosine kinase c-Src is believed to result in signal transduction, cytoskeletal and adhesion changes, ultimately promoting a tumor-invasive phenotype. We report here the discovery of a new class of anilinoquinazoline inhibitors with high affinity and specificity for the tyrosine kinase domain of the c-Src enzyme. Special attention was directed toward finding inhibitors selective against KDR tyrosine kinase in order to ensure that the in vivo profile of a specific Src inhibitor could be determined. The 4-aminobenzodioxole quinazoline series gave compounds with excellent potency and selectivity. The most interesting compounds were evaluated in vivo and displayed good pharmacokinetics following oral dosing. Compounds such as the aminobenzodioxoles were shown to be potent inhibitors of tumor growth in a c-Src-transformed 3T3 xenograft model in vivo, resulting in more than 90% growth inhibition at doses as low as 6 mg/kg po once daily. Src tyrosine kinase inhibitors such as these may provide a novel therapeutic modality for targeting cancer invasion and metastasis.

Kinases, Homology Models, and High Throughput Docking

With the many protein sequences coming from the genome sequencing projects, it is unlikely that we will ever have an atomic resolution structure of every relevant protein. With high throughput crystallography, however, we will soon have representative structures for the vast majority of protein families. Thus the drug discovery and design process will rely heavily on protein modeling to address issues such as designing combinatorial libraries for an entire class of targets and engineering genome-wide selectivity over a target class. In this study we assess the value of high throughput docking into homology models. To do this we dock a database of random compounds seeded with known inhibitors into homology models of six different kinases. In five of the six cases the known inhibitors were found to be enriched by factors of 4-5 in the top 5% of the overall scored and ranked compounds. Furthermore, in the same five cases the known inhibitors were found to be enriched by factors of 2-3 in the top 5% of the scored and ranked known kinase inhibitors, thus showing that the homology models can pick up some of the crucial selectivity information.

Pyrrolopyrimidine c-Src inhibitors reduce growth, adhesion, motility and invasion of prostate cancer cells in vitro

Two bona fide c-Src inhibitors, denominated CGP77675 and CGP76030, reduced in a time- and concentration-dependent manner (i) the proliferation of the PC3 prostate carcinoma cell line, as assessed by the [3H]-thymidine incorporation test, (ii) the capacity of PC3 cells to adhere and spread on Matrigel substrate, as determined by crystal violet staining, (iii) the ability of PC3 cells to migrate through a gelatine boundary and invade a Matrigel substrate. The latter effect was not due to a decrease of urokinase-type plasminogen activator (uPA), nor of metalloproteinase-2 (MMP-2) activities. The MMP-9 activity, along with the expression of the Tissue Inhibitor of Metalloproteinases (TIMP)-1 and TIMP-2, were reduced by the two inhibitors, consistent with the ability of c-Src to enhance MMP-9 and TIMP expression levels. Collectively, these data demonstrate that the pyrrolopyrimidine-derived c-Src inhibitors significantly reduced PC3 cell activities associated with their malignant phenotype.

BCR-ABL independence and LYN kinase overexpression in chronic myelogenous leukemia cells selected for resistance to STI571

Clinical studies have shown that the tyrosine kinase inhibitor STI571 effectively controls BCR-ABL-positive chronic myelogenous leukemia (CML). However, disease progression while on STI571 therapy has been reported, suggesting de novo or intrinsic resistance to BCR-ABL-targeted therapy. To investigate possible mediators of acquired STI571 resistance, K562 cells resistant to 5 microM STI571 (K562-R) were cloned and compared to the parental cell population. K562-R cells had reduced BCR-ABL expression and limited activation of BCR-ABL signaling cascades (Stat 5, CrkL, MAPK). STI571 failed to activate caspase cascades or to suppress expression of survival genes (bcl-xL) in resistant cells. Gene sequencing and tyrosine kinase activity measurements demonstrated that K562-R cells retained wild-type and active BCR-ABL tyrosine kinase that was inhibitable by in vitro incubation with STI571, suggesting that BCR-ABL was not coupled to proliferation or survival of K562-R cells. The src-related kinase LYN was highly overexpressed and activated in K562-R cells, and its inhibition reduced proliferation and survival of K562-R cells while having limited effects of K562 cells. Specimens taken from patients with advanced CML that progressed on STI571 therapy also were analyzed for LYN kinase expression, and they were found to be elevated to a level similar to that of K562-R cells. Comparison of samples from patients taken prior to and following STI571 failure suggested that expression and/or activation of LYN/HCK occurs during disease progression. Together, these results suggest that acquired STI571 resistance may be associated with BCR-ABL independence and mediated in part through overexpression of other tyrosine kinases.

8-Anilinoimidazo[4,5-g]quinoline-7-carbonitriles as Src kinase inhibitors

A series of 8-anilinoimidazo[4,5-g]quinoline-7-carbonitriles was synthesized and evaluated as Src kinase inhibitors. Several aniline substituents were surveyed, as well as water-solubilizing groups at the C-2 and N-3 positions. Potent Src inhibitors were identified, with N-3 providing the best position for an additional water-solubilizing group.

Substituted 4-anilino-7-phenyl-3-quinolinecarbonitriles as Src kinase inhibitors

A series of substituted 4-anilino-7-phenyl-3-quinolinecarbonitriles has been prepared as Src kinase inhibitors. Optimal activity is observed with compounds that have basic amines attached via the para position of the 7-phenyl ring, and a hydrogen atom at the C-6 position. The best compounds are low nanomolar inhibitors of Src kinase, and have potent activity against Src-transformed fibroblast cells.

Inhibition of Src kinase activity by 4-anilino-7-thienyl-3-quinolinecarbonitriles

Based on a screening lead from a yeast-based assay to identify Src family kinase inhibitors, a series of 4-anilino-7-thienyl-3-quinolinecarbonitriles was prepared. When the thiophene ring was substituted with a water-solubilizing group in a 2,5-, 3,5- or 2,4-pattern, potent inhibition of Src kinase activity was observed.

Pyrrolo[2,3-d]pyrimidines containing diverse N-7 substituents as potent inhibitors of Lck

A series of pyrrolo[2,3-d]pyrimidines was synthesized and evaluated as inhibitors of Lck. Lck accommodates a diverse set of substituents at N-7. Altering the substituent at N-7 provided compound 13, an orally available lck inhibitor which inhibited TCR mediated IL-2 production after oral dosing.

Cell permeability as a parameter for lead generation in the protein Tyrosine kinase inhibition field

Based on the inverse relationship between polar surface area and cell permeability and capitalizing on the properties of pyrrolopyrimidines 1 as protein tyrosine kinase inhibitors, pyrrolopyridones 2 were designed and synthesized as potential leads for the development of novel inhibitors with improved cell permeability properties.

7-Alkyl- and 7-cycloalkyl-5-aryl-pyrrolo[2,3-d]pyrimidines--potent inhibitors of the tyrosine kinase c-Src

7-Substituted-5-aryl-pyrrolo[2,3-d]pyrimidines have been prepared starting from alpha-bromoacetophenones. These compounds represent a novel class of potent inhibitors of the tyrosine kinase pp60(c-Src) with good specificity towards other tyrosine kinases (EGF-R, v-Abl).

7-Pyrrolidinyl- and 7-piperidinyl-5-aryl-pyrrolo[2,3-d]pyrimidines--potent inhibitors of the tyrosine kinase c-Src

7-Heterocyclyl-5-aryl-pyrrolo[2,3-d]pyrimidines represent a new class of highly potent and selective inhibitors of the tyrosine kinase pp60(c-Src).

Synthesis and Src kinase inhibitory activity of a series of 4-phenylamino-3-quinolinecarbonitriles

Screening of a directed compound library in a yeast-based assay identified 4-[(2,4-dichlorophenyl)amino]-6,7-dimethoxy-3-quinolinecarbonitrile (2a) as a Src inhibitor. An enzymatic assay established that 2a was an ATP-competitive inhibitor of the kinase activity of Src. We present here SAR data for 2a which shows that the aniline group at C-4, the carbonitrile group at C-3, and the alkoxy groups at C-6 and C-7 of the quinoline are crucial for optimal activity. Increasing the size of the C-2 substituent of the aniline at C-4 of 2a from chloro to bromo to iodo resulted in a corresponding increase in Src inhibition. Furthermore, replacement of the 7-methoxy group of 2a with various 3-heteroalkylaminopropoxy groups provided increased inhibition of both Src enzymatic and cellular activity. Compound 25, which contains a 3-morpholinopropoxy group, had an IC(50) of 3.8 nM in the Src enzymatic assay and an IC(50) of 940 nM for the inhibition of Src-dependent cell proliferation.

Src inhibitors: drugs for the treatment of osteoporosis, cancer or both?

Src was one of the first proto-oncogenes to be identified and is a prototype of non-receptor type tyrosine kinases. The role of Src in bone metabolism first became apparent in Src-deficient mice and has been confirmed using low-molecular-weight Src inhibitors in animal models of osteoporosis. At the cellular level, it is well established that Src plays an important role in proliferation, and adhesion and motility. In addition, recent data indicate an involvement of Src in cell survival and intracellular trafficking in various specialized cell types. These new findings suggest that Src inhibitors might have therapeutic value in the suppression of tumor growth, tumor angiogenesis and bone resorption.

Inhibitors of src tyrosine kinase: the preparation and structure-activity relationship of 4-anilino-3-cyanoquinolines and 4-anilinoquinazolines

Src is a nonreceptor tyrosine kinase involved in signaling pathways that control proliferation, migration, and angiogenesis. Increased Src expression and activity are associated with an increase in tumor malignancy and poor prognosis. Several quinolines and quinazolines were identified as potent and selective inhibitors of Src kinase activity.

Cardiac chloride channels: physiology, pharmacology and approaches for identifying novel modulators of activity

Drugs that block cardiac cation channels have been marketed as the therapeutic answer to cardiac arrhythmia. However, such molecules have been only moderately successful at improving the survival of cardiac patients, and so new targets have been needed for future antiarrhythmic agents. This article outlines the properties and roles of Cl(-) channels, which are one of these new targets, and describes an approach for identifying novel CI(2) channel modulators.