Structural modification of an EGFR inhibitor that showed weak off-target activity against RET leading to the discovery of a potent RET inhibitor.

Here, we describe the structural optimization of a known EGFR inhibitor (compound 1) that showed weak off-target activity against RET. Twenty-six analogs of 1 were synthesized. SAR analysis led to the discovery of several compounds that showed considerable potency against the RET-dependent thyroid cancer cell line TT. Kinase inhibitory potency was then measured for the most active compound (2u) in the cellular assay. The results showed that 2u is a potent RET inhibitor with an IC(50) value of 7 nM.

Discovery of novel fatty acid synthase (FAS) inhibitors based on the structure of ketoaceyl synthase (KS) domain.

Development of fatty acid synthase (FAS) inhibitors has increasingly attracted much attention in recent years due to their potential therapeutic use in obesity and cancers. In this investigation, pharmacophore modeling based on the first crystal structure of human KS domain of FAS was carried out. The established pharmacophore model was taken as a 3D query for retrieving potent FAS inhibitors from the chemical database Specs. Docking study was further carried out to refine the obtained hit compounds. Finally, a total of 28 compounds were selected based on the ranking order and visual examination, which were first evaluated by a cell line-based assay. Seven compounds that have good inhibition activity against two FAS overexpressing cancer cell lines were further evaluated by an enzyme-based assay. One compound with a new chemical scaffold was found to have low micromolar inhibition potency against FAS, which has been subjected to further chemical structural modification.

Implications of soluble E-cadherin level of antiviral treatment in patients with chronic hepatitis C virus infection.

BACKGROUND AND AIMS: Soluble E-cadherin (sE-cadherin) has been observed elevated in patients with various diseases, and implicated in the occurrence and development of those diseases. The implications of sE-cadherin in chronic hepatitis C virus (HCV) infection are still unclear. The purpose of this study is to explore the significance of sE-cadherin in chronic hepatitis C infection and the correlation with treatment response. METHODS: 87 chronic HCV infected patients and 60 healthy subjects were enrolled in this study. Blood samples from patients receiving the combined treatment of pegylated interferon-a (Peg-IFN-α) with ribavirin (RBV) were collected before treatment, during 4th, 12th therapy weeks, end of the treatment, and 24 weeks post-therapy. Plasma sE-cadherin level was detected by enzyme-linked immunosorbent assay (ELISA) and the relationship between sE-cadherin and antiviral treatment outcome was analyzed. RESULTS: Plasma sE-cadherin concentrations of Chronic HCV infected patients were significantly higher than that of healthy controls. A strong correlation between sE-cadherin level and the HCV viral load, alanine aminotransferase (ALT), aspartate aminotransferase (AST), and also glutamyl transpeptidase (GGT) level was detected. Chronic HCV infected patients achieving rapid virological response (RVR) and sustained virological response (SVR) had lower baseline sE-cadherin concentrations compared with the non-RVR and non-SVR groups respectively. Univariate and multivariate regression analyses suggested that baseline plasma sE-cadherin level was predictive of therapeutic effect in patients with chronic HCV infection. CONCLUSION: Baseline sE-cadherin level could be considered as an independent predictor of SVR with Peg-IFN-α plus ribavirin therapy in the Chinese Han population chronic HCV infection patients. Effective antiviral therapy might restore sE-cadherin at physiological levels.

[Expression and variation of angiotensin II type 1 receptor on vascular smooth muscle cells of systemic and pulmonary circulations in experimental ventricular septal defect in pigs].

OBJECTIVE: To investigate the expression of angiotensin II type 1 receptor (AT1R) on the vascular smooth muscle cells (VSMC) of both systemic and pulmonary circulations and their variation caused by intracardiac left to right shunting using an animal model of the ventricular septal defect (VSD). METHODS: Nineteen young pigs were divided into 3 groups: operation (experimental VSD), sham-operation, and normal control. One month after operation, the pigs were catheterized and then put to death. Smooth muscle cells were taken from aorta, pulmonary artery, pulmonary arteriole, mesenteric arteriole and VSMC were isolated. Radioligand binding assay for AT1R was done to measure the Bmax and KD. RESULTS: There were no significant differences in Bmax and KD of AT1R between the sham-operation group and the control. Bmax of the aorta (112.11+/-35.77) fmol/10(6), main pulmonary artery (52.37+/-31.09) fmol/10(6) and mesenteric arteriole (106.98+/-100.48) fmol/10(6) in the operation group were remarkably elevated in comparison with the control (P<0.05). In the operation group, Bmax of the aorta VSMC was higher than that of main pulmonary artery VSMC (P<0.05), and Bmax of the mesenteric arteriole VSMC was higher than that of the small pulmonary arteriole VSMC (P<0.05). CONCLUSION: The findings in AT1R expression in experimental VSD were supportive to the previously proposed hypothesis that ATR expression might be stronger in systemic VSMC than in pulmonary VSMC in young animal, especially in the presence of intracardiac left to right shunt, which may provide a sound rationale for the pharmacological management of VSD infants with angiotensin converting enzyme inhibitor or AT1R antagonist.

Identification of novel anaplastic lymphoma kinase (ALK) inhibitors using a common feature pharmacophore model derived from known ligands crystallized with ALK.

In this investigation, a common feature pharmacophore model of anaplastic lymphoma kinase inhibitors was developed based on several known anaplastic lymphoma kinase inhibitors that were co-crystallized with anaplastic lymphoma kinase. The established pharmacophore model Hypo1 was carefully validated and then adopted to screen two in silico chemical databases, Specs (202 408 compounds) and Enamine (1 105 894 compounds), for retrieving novel anaplastic lymphoma kinase inhibitors. The hit compounds were further filtered using a fast bumping-check tool and molecular docking. Finally, 25 compounds were selected and purchased from market. The bioactivity of these compounds was firstly measured at the cellular level against a typical anaplastic lymphoma kinase mutant-driven cancer cell line, Karpas299. And six of them showed a good anti-viability activity. The kinase inhibitory potency against the recombinant human anaplastic lymphoma kinase kinase was tested to the most active compound at the cellular level, T0508-5181 (from Specs), which gave a half maximal inhibitory concentration (IC(50)) of 5.3 µM.

Retrieving novel C5aR antagonists using a hybrid ligand-based virtual screening protocol based on SVM classification and pharmacophore models.

C5aR antagonists have been thought as potential immune mediators in various inflammatory and autoimmune diseases, and discovery of C5aR antagonists has attracted much attention in recent years. The discovery of C5aR antagonists was usually achieved through high-throughput screening, which usually suffered a high cost and a low success rate. Currently, the fast developing computer-aided virtual screening (VS) methods provide economic and rapid approaches to the lead discovery. In this account, we proposed a hybrid ligand-based VS protocol that is based on support vector machine (SVM) classification and pharmacophore models for retrieving novel C5aR antagonists. Performance evaluation of this hybrid VS protocol in virtual screening against a large independent test set, T-CHEM, showed that the hybrid VS approach significantly increased the hit rate and enrichment factor compared with the individual SVM classification model-based VS and pharmacophore model-based VS, as well as molecular docking-based VS in that the receptor structure was created by homology modeling. The hybrid VS approach was then used to screen several large chemical libraries including PubChem, Specs, and Enamine. Finally, a total of 20 compounds were selected from the top ranking hits, and shifted to the subsequent in vitro and in vivo studies, which results will be reported in the near future.

Discovery of novel Bruton's tyrosine kinase inhibitors using a hybrid protocol of virtual screening approaches based on SVM model, pharmacophore and molecular docking.

Bruton's tyrosine kinase has emerged as a potential target for the treatment for B-cell malignancies and autoimmune diseases. Discovery of Bruton's tyrosine kinase inhibitors has thus attracted much attention recently. In this investigation, we introduced a hybrid protocol of virtual screening methods including support vector machine model-based virtual screening, pharmacophore model-based virtual screening and docking-based virtual screening for retrieving new Bruton's tyrosine kinase inhibitors from commercially available chemical databases. Performances of the hybrid virtual screening approach were evaluated against a test set, which results showed that the hybrid virtual screening approach significantly shortened the overall screening time, and considerably increased the hit rate and enrichment factor compared with the individual method (SB-VS, PB-VS and DB-VS) or their combinations by twos. This hybrid virtual screening approach was then applied to screen several chemical databases including Specs (202,408 compounds) and Enamine (980,000 compounds) databases. Thirty-nine compounds were selected from the final hits and have been shifted to experimental studies.

Discovery of N6-phenyl-1H-pyrazolo[3,4-d]pyrimidine-3,6-diamine derivatives as novel CK1 inhibitors using common-feature pharmacophore model based virtual screening and hit-to-lead optimization.

Aberrant activation of casein kinase 1 (CK1) has been demonstrated to be implicated in the pathogenesis of cancer and various central nervous system disorders. Discovery of CK1 inhibitors has thus attracted much attention in recent years. In this account, we describe the discovery of N6-phenyl-1H-pyrazolo[3,4-d]pyrimidine-3,6-diamine derivatives as novel CK1 inhibitors. An optimal common-feature pharmacophore hypothesis, termed Hypo2, was firstly generated, followed by virtual screening using Hypo2 against several chemical databases. One of the best hit compounds, N6-(4-chlorophenyl)-1H-pyrazolo[3,4-d]pyrimidine-3,6-diamine, was chosen for the subsequent hit-to-lead optimization under the guide of Hypo2, which led to the discovery of a new lead compound (1-(3-(3-amino-1H-pyrazolo[3,4-d]pyrimidin-6-ylamino)phenyl)-3-(3-chloro-4-fluorophenyl)urea) that potently inhibits CK1 with an IC(50) value of 78 nM.

Discovery of the novel potent and selective FLT3 inhibitor 1-{5-[7-(3- morpholinopropoxy)quinazolin-4-ylthio]-[1,3,4]thiadiazol-2-yl}-3-p-tolylurea and its anti-acute myeloid leukemia (AML) activities in vitro and in vivo.

Structure-activity relationship (SAR) studies of 2-(quinazolin-4-ylthio)thiazole derivatives, which are for optimizing the in vitro and in vivo antiacute myeloid leukemia (AML) activity of a previously identified FLT3 inhibitor 2-(6,7-dimethoxyquinazolin-4-ylthio)thiazole (1), are described. SAR studies centering around the head (thiazole) and tails (6- and 7-positions) of the quinazoline moiety of 1 led to the discovery of a series of compounds that exhibited significantly increased potency against FLT3-driven AML MV4-11 cells. Preliminary in vivo assays were carried out on three highly active compounds, whose results showed that 1-{5-[7-(3-morpholinopropoxy)quinazolin-4-ylthio]-[1,3,4]thiadiazol-2-yl}-3-p-tolylurea (20c) had the highest in vivo activity. Further in vitro and in vivo anti-AML studies were then performed on 20c; in an MV4-11 xenograft mouse model, a once-daily dose of 20c at 100 mg/kg for 18 days led to complete tumor regression without obvious toxicity. Western blot and immunohistochemical analysis were carried out to illustrate the mechanism of action of 20c.

Systems biology modeling reveals a possible mechanism of the tumor cell death upon oncogene inactivation in EGFR addicted cancers.

Despite many evidences supporting the concept of "oncogene addiction" and many hypotheses rationalizing it, there is still a lack of detailed understanding to the precise molecular mechanism underlying oncogene addiction. In this account, we developed a mathematic model of epidermal growth factor receptor (EGFR) associated signaling network, which involves EGFR-driving proliferation/pro-survival signaling pathways Ras/extracellular-signal-regulated kinase (ERK) and phosphoinositol-3 kinase (PI3K)/AKT, and pro-apoptotic signaling pathway apoptosis signal-regulating kinase 1 (ASK1)/p38. In the setting of sustained EGFR activation, the simulation results show a persistent high level of proliferation/pro-survival effectors phospho-ERK and phospho-AKT, and a basal level of pro-apoptotic effector phospho-p38. The potential of p38 activation (apoptotic potential) due to the elevated level of reactive oxygen species (ROS) is largely suppressed by the negative crosstalk between PI3K/AKT and ASK1/p38 pathways. Upon acute EGFR inactivation, the survival signals decay rapidly, followed by a fast increase of the apoptotic signal due to the release of apoptotic potential. Overall, our systems biology modeling together with experimental validations reveals that inhibition of survival signals and concomitant release of apoptotic potential jointly contribute to the tumor cell death following the inhibition of addicted oncogene in EGFR addicted cancers.