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Synthesis and biological evaluation of novel quinazoline-derived human Pin1 inhibitors.

A series of novel 2,4-disubstituted quinazoline derivatives were prepared and their inhibitory activities on hPin1 were evaluated. Of all the synthesized compounds, eight compounds displayed inhibitory activities with IC(50) value at the level of 10(-6)mol/L. Preliminary structure-activity relationships were analyzed in details and the binding mode of the titled compounds was predicted using FlexX algorithm. The design and optimization of novel small molecule Pin1 inhibitors will be guided by the results of this report.

Inhibition of gastric tumor growth by a novel Hsp90 inhibitor.

Heat shock protein 90 (Hsp90) is a molecular chaperone engaging in multiple cellular signaling by stabilizing oncoproteins (e.g. Akt and c-Raf) in tumor cells. Whereas Hsp90 inhibitors such as 17-AAG exert promising antitumor effects in clinical trials, current efforts focus on developing agents targeting Hsp90 with improved efficacy and lower toxicity. Using a fluorescence polarization assay, we screened over a hundred of synthetic small molecules and identified a resorcinol derivative LD053 that bound the Hsp90 ATP-binding pocket. The binding of LD053 to Hsp90 dissociated the co-chaperone protein cdc37 from Hsp90, resulting in destabilization of Akt and c-Raf and subsequent inhibition of PI3K/Akt and c-Raf/Mek/Erk signaling in BGC823 gastric cancer cells. As a consequence, LD053 decreased cancer cell viability and induced apoptosis evidenced by increased subG0/G1 cell population and increased cleavage of caspase 3 and PARP. Interestingly, normal human cells appeared insensitive to LD053 treatments. Consistent with its in vitro anticancer activities, LD053 significantly inhibited growth of BGC823 xenografts in nude mice without apparent body weight loss. These results thus demonstrate that LD053 is a novel Hsp90 inhibitor and has potential to be used to treat gastric cancer.

Synthesis and antiproliferative evaluation of novel benzoimidazole-contained oxazole-bridged analogs of combretastatin A-4

A series of novel oxazole-bridged analogs of combretastatin A-4 bearing a benzo[d]-imidazole as B ring were synthesized and evaluated for antiproliferative activities against five human cancer cell lines. Among all the synthesized compounds, the N-unsubstituted benzoimidazole analog 5 and the analogs 6b, 7a and 7b with a small hydrophobic group on nitrogen atom of benzoimidazole ring were identified as the most potent inhibitors of tumor cell growth with IC50 values at nanomolar levels (5, IC50=8.4 nM, HT29; 6b, 7a, 7b, IC50=9.6 nM, 3.8 nM, 3.0 nM, A549). In a murine H22 tumor xenograft model, compound 5 exhibited significant antitumor activity. The binding mode of compound 5 in the colchicine binding site of tubulin was probed.

Synthesis and biological evaluation of novel human Pin1 inhibitors with benzophenone skeleton.

A series of novel benzophenone derivatives were prepared and their inhibitory activities were evaluated on hPin1. Of all the synthesized compounds, the most active compound displayed inhibitory activities with an IC(50) value of 5.99 μmol/L. Preliminary structure-activity relationships were analyzed in details and the binding mode of the titled compounds was predicted using FlexX algorithm. The results of this research will shed light on further design and optimization of novel small molecule Pin1 inhibitors.

Synthesis and Pin1 inhibitory activity of thiazole derivatives

Pin1 (Protein interacting with NIMA1) is a peptidyl prolyl cis-trans isomerase (PPIase) which specifically catalyze the conformational conversion of the amide bond of pSer/Thr-Pro motifs in its substrate proteins and is a novel promising anticancer target. A series of new thiazole derivatives were designed and synthesized, and their inhibitory activities were measured against human Pin1 using a protease-coupled enzyme assay. Of all the tested compounds, a number of thiazole derivatives bearing an oxalic acid group at 4-position were found to be potent Pin1 inhibitors with IC50 values at low micromolar level. The detailed structure-activity relationships were analyzed and the binding features of compound 10b (IC50 5.38μM) was predicted using CDOCKER program. The results of this research would provide informative guidance for further optimizing thiazole derivatives as potent Pin1 inhibitors.

Development of a selective S1P1 receptor agonist, Syl930, as a potential therapeutic agent for autoimmune encephalitis

Sphingosine-1-phosphate receptor subtype 1 (S1P1) is essential for lymphocyte egress from secondary lymphoid organs and is a validated drug target for the treatment of autoimmune disorders. However, during the preclinical and clinical trials of S1P1 modulators, the undesired activation of S1P3, a subtype of sphingosine 1-phosphate (S1P) receptors family, by S1P1 modulators often results in bradycardia in patients. Thus, we designed and synthesized a new series of selective S1P1 agonists. One of them, Syl930 (the prodrug), is preference to activate S1P1 but not S1P3. In this study, we further investigated the therapeutic potential of Syl930 on an experimental autoimmune encephalomyelitis (EAE) model in Lewis rats. We found that Syl930 can activate and internalize S1P1 receptors and effectively decreased the periphery blood lymphocytes (PBL) in SD rats, and subsequently rendered PBL insensitive to egress signal from secondary lymphoid organs (SLO). Intriguingly, the treatment of Syl930 did not bring any side effect on heart rate of the tested rats. Furthermore, the suppressed PBL caused by Syl930 was able to recover within 3 days after the last dose of treatment, which is correlated to the relatively short elimination half-life of Syl930. In the rat EAE model, therapeutic treatment with Syl930 significantly inhibited the progression of EAE and EAE-associated histological changes in brain and spinal cord of Lewis rats. These results illustrate that, as a selective S1P1 agonist, Syl930 exhibits a profound and rapidly reversible suppression of lymphocyte trafficking and it has the potential to serve as a therapeutic agent for autoimmune encephalitis.

A novel derivative of quinazoline, WYK431 induces G2/M phase arrest and apoptosis in human gastric cancer BGC823 cells through the PI3K/Akt pathway

WYK431, a novel synthetic quinazoline derivative, showing potent inhibition of proliferation activity against a broad spectrum of human cancer cell lines. We investigated the anticancer effects of WYK431 on BGC823 cells both in vitro and in vivo. The results showed that WYK431 inhibited proliferation, arrested the cell cycle at the G(2)/M phase, which was related to CDK1 and CDC25C, and induced apoptosis associated with activation of caspase-3 and caspase-9 rather than caspase-8 in BGC823 cells. Treatment of BGC823 cells with WYK431 resulted in upregulation of Bax, release of cytochrome c from the mitochondria to the cytosol and disruption of mitochondrial membrane potential. Western blot analysis showed that WYK431 downregulated the levels of the PI3K/Akt signaling pathway. Moreover, WYK431 effectively suppressed tumor growth in xenograft models in BALB/c athymic nude mice without major side action. TUNEL analysis showed that WYK431 induced BGC823 cell apoptosis in vivo. Collectively, WYK431 is a novel small molecule agent which inhibits BGC823 cell proliferation inducing G(2)/M phase arrest and apoptosis via the mitochondrial apoptotic pathway. To assess its potential as a promising anticancer agent requires further investigation.

Antiproliferative Effect of HSP90 Inhibitor Y306zh Against Pancreatic Cancer is Mediated by Interruption of AKT and MAPK Signaling Pathways

BACKGROUND AND AIM Inhibition of HSP90 is a potential strategy to treat pancreatic cancer (PC), since many client proteins of HSP90 are found to be over-expressed and/or genetically mutated in PC. These client proteins directly participate in the modulation of proliferation and aggravation of PC. Our previous works led to Y306zh as a novel and potent HSP90 inhibitor. In this study we further investigated the mode of actions of Y306zh as an anti-PC agent. MATERIALS AND METHODS The binding affinity of Y306zh towards HSP90 was analyzed by fluorescence polarization assay. The anti-proliferative activities and molecular mechanism of Y306zh were investigated in human PC cell lines and Miapaca2 xenograft model. RESULTS Y306zh binds tightly to the NH2-terminus of HSP90 with an IC50 of 85 nM, and this causes ATP incapable to attach to the same binding site, and disrupts HSP90-p23 association. Y306zh also induces the expression of HSP70, recruits the complex of CHIP, HSP70 and HSP90, and eventually results in the degradation of HSP90 client proteins (EGFR, AKT, C-RAF and CDK4) via proteasomal pathway. Amazingly, coincident with the molecular mechanism, Y306zh also inhibits the proliferation of PC cells through G2/M phase arrest, but appears to be totally insensitive to normal mammalian cells. Furthermore, Y306zh effectively inhibits tumor growth of Mia-paca2 xenograft mice without any obvious effect on body weight. CONCLUSIONS Y306zh, a novel HSP90 inhibitor, interrupts ATP binding to HSP90 and disrupts HSP90-p23 interaction, and eventually inhibits the growth of PC cells.

Design, synthesis and docking-based 3D-QSAR study of novel 2-substituted 2-aminopropane-1,3-diols as potent and selective agonists of sphingosine-1-phosphate 1 (S1P1) receptor

Spingosine-1-phosphate receptor 1 (S1P1) has been actively pursued as an important therapeutic target in immune regulation. A series of 2-substituted 2-aminopropane-1,3-diols were designed and synthesized as selective S1P1 agonists. Most of the compounds with a biphenyl ether scaffold showed moderate to excellent S1P1/S1P3 selectivity. Compound 40c is identified as a potent S1P1 agonist with 350-fold S1P1/S1P3 selectivity. 39c, the alcohol form of 40c exerted good lymphopenia activity in vivo but with weak influence on heart rate. To investigate the SARs of 2-substituted 2-aminopropane-1,3-diols in more details, COMFA (q2 = 0.547, r2 = 0.986) and COMSIA (q2 = 0.544, r2 = 0.943) models were established based on molecular docking alignment, which were validated with high reliability in predicting activities of agonists. The 3D-QSAR models will be helpful in the design of novel, potent and selective S1P1 agonists.

Activity of the potent dual Abl/Src tyrosine kinase inhibitor FB2 against Bcr–Abl positive cell lines in vitro and in vivo

We have previously shown the inhibition of the small-molecule inhibitor FB2 on imatinib-sensitive and resistance CML cell lines with the wild-type Bcr-Abl fusion gene. Here we report the potent and selective antiproliferation on FB2 on transfected Ba/F3 p210 cell lines expressing various isoforms of Bcr-Abl (wild-type, Y253F, T315I). FB2 which orients Bcr-Abl and Src kinase activities, is shown to override imatinib-resistance CML involving Y253F mutation in the Abl kinase domain of the fusion protein except T315I in vivo and in vitro. Thus, we present FB2 that displays potency toward Bcr-Abl and Src as the molecular target, and which could potentially be used to override drug resistance in CML.