Xuewu Liang

VEGF signal system: the application of antiangiogenesis.

Among the numerous endogenous promoters of angiogenesis, vascular endothelia growth factor (VEGF) plays a leading role in angiogenesis, which has huge impact on proliferation, survival, migration and permeability of tumor cells. VEGF signal system also becomes remarkable anticancer targets, including VEGF, vascular endothelia growth factor receptor (VEGFR), and VEGF downstream signal pathways. So far, there has been many clinical or approved anticancer drugs that directly or indireactly interfere with VEGF signal system applied in the treatment of various tumors and other diseases associated with pathological angiogenesis. Various kinds of antiangiogenic agents which inhibit VEGF and VEGFR have been developed and discovered gradually, including antibodies, ribozymes and small molecule inhibitors. Meanwhile, the investigation into antiangiogenic agents which block certain signal proteins of VEGF downstream signal pathways attracts the attention of medicinal chemists and enriches the application of antiangiogenic agents. This review will interpret the mysterious VEGF signal system from its molecular structure and probe to the mechanism of the combination of VEGF and its receptors. Furthermore, the detail of VEGF signal pathways will be introduced comprehensively and methodically. In addition, some up-to-date clinical or approved anticancer agents will be clearly tabulated. The binding modes of different kinase inhibitors will be used to explain the SAR of the small molecule inhibitors. Finally, in order to make the readers master VEGF signal system completely, some novel targets and inhibitors which block the downstream signal pathways of VEGF are plainly stated.

Novel β-dicarbonyl derivatives as inhibitors of aminopeptidase N (APN)

Most zinc metalloproteases are over-expressed in tumor cells and play a critical role in the genesis, development, and metastasis of tumors. Novel zinc binding groups (ZBGs) represent a novel strategy to obtain optimal potency and selectivity for zinc metalloproteases inhibitors. Here we described the design, synthesis, and biological studies of novel β-dicarbonyl derivatives as aminopeptidase N (APN/CD13) inhibitors. The results demonstrated that some compounds exhibited moderate to good inhibitory activities against APN with compound 5c being the most potent, suggesting that 5c could serve as new lead for the future APN inhibitor development. The results further confirm our design rationale of β-dicarbonyl moiety as a new ZBG, which may provide a new direction for the design and discovery of zinc metalloproteases inhibitors as new anti-tumor agents.

JAK/STAT Signal Transduction: Promising Attractive Targets for Immune, Inflammatory and Hematopoietic Diseases

BACKGROUND JAK/STAT signal pathway, a requisite part in the signaling process of growth factors and cytokines, has become attractive targets for numerous immune, inflammatory and hematopoietic diseases. OBJECTIVE Herein, we present a review of the JAK/STAT signal pathway, the structure, biological function, mechanism of the JAKs and STATs along with a summary of the up-to-date clinical or approved JAK inhibitors which are involved in the treatment of various kinds of tumors and other immunity indications. Moreover, kinds of recently discovered JAKs inhibitors with potent activity or promising selectivity are also briefly discussed. CONCLUSION Research and development of isoform selective JAK inhibitors has become a hot topic in this field. With the assistance of high throughput screening and rational drug design, more and more JAK inhibitors with improved selective profiles will be discovered as biological probes and even therapeutic agents.

Design, synthesis and anti-tumor activity study of novel histone deacetylase inhibitors containing isatin-based caps and o-phenylenediamine-based zinc binding groups

As a hot topic of epigenetic studies, histone deacetylases (HDACs) are related to lots of diseases, especially cancer. Further researches indicated that different HDAC isoforms played various roles in a wide range of tumor types. Herein a novel series of HDAC inhibitors with isatin-based caps and o-phenylenediamine-based zinc binding groups have been designed and synthesized through scaffold hopping strategy. Among these compounds, the most potent compound 9n exhibited similar if not better HDAC inhibition and antiproliferative activities against multiple tumor cell lines compared with the positive control entinostat (MS-275). Additionally, compared with MS-275 (IC50 values for HDAC1, 2 and 3 were 0.163, 0.396 and 0.605µM, respectively), compound 9n with IC50 values of 0.032, 0.256 and 0.311µM for HDAC1, 2 and 3 respectively, showed a moderate HDAC1 selectivity.

Development of N-hydroxycinnamamide-based HDAC inhibitors with improved HDAC inhibitory activity and in vitro antitumor activity

Histone deacetylase inhibitors (HDACIs) are promising in the treatment of various diseases, among which cancer treatment has achieved the most success. We have previously developed series of HDACIs combining N-hydroxycinnamamide bioactive fragment and indole bioactive fragment, which showed moderate to potent antitumor activities. Herein, further structural derivatization based on our previous structure-activity relationship (SAR) got 25 novel compounds. Most compounds showed much more potent histone deacetylases (HDACs) inhibitory activity than their parent compound 1 and even the positive control SAHA. Whats more, compared with the approved HDACs inhibitor SAHA, compounds 6i, 6k, 6q and 6t displayed better in vitro antiproliferation against multiple tumor cell lines. It is worth noting that though the 4-hydroxycinnamic acid-based compound 2 showed HDAC1/3 dual selectivity, its 4-hydroxy-3-methoxycinnamic acid-based analog 6t turned out to be a pan-HDACs inhibitor as SAHA, indicating that the 3-methoxy group on the N-hydroxycinnamamide fragment could dramatically influence the HDACs isoform selectivity of this series of compounds.

Design, synthesis and preliminary biological evaluation of 4-aminopyrazole derivatives as novel and potent JAKs inhibitors.

JAKs inhibitors were widely applied in the treatment of immunodeficiency diseases, inflammation and cancers. We designed and synthesized a novel series of 4-aminopyrazole derivatives, which showed inhibitory potency against various JAKs. The in vitro protein kinase inhibition experiment indicated that compounds 17k, 17l, 17m and 17n could inhibit JAKs effectively. Among them, compound 17m possessed the highest protein kinase inhibitory rates (%) at 10μM, which were 97, 96 and 100 to JAK1, JAK2 and JAK3, respectively. Further evaluation revealed that the IC50 values of 17m against JAK1, JAK2 and JAK3 were 0.67μM, 0.098μM and 0.039μM, respectively. Moreover, western blotting results showed compound 17m could inhibit the phosphorylation of JAK2 in Hela cells effectively. The data supports the further investigation of these compounds as novel JAKs inhibitors.

Optimization of N-Substituted Oseltamivir Derivatives as Potent Inhibitors of Group-1 and-2 Influenza A Neuraminidases, Including a Drug-Resistant Variant

On the basis of our earlier discovery of N1-selective inhibitors, the 150-cavity of influenza virus neuraminidases (NAs) could be further exploited to yield more potent oseltamivir derivatives. Among the synthesized compounds, 15b and 15c were exceptionally active against both group-1 and -2 NAs. Especially for 09N1, N2, N6, and N9 subtypes, they showed 6.80-12.47 and 1.20-3.94 times greater activity than oseltamivir carboxylate (OSC). They also showed greater inhibitory activity than OSC toward H274Y and E119V variant. In cellular assays, they exhibited greater potency than OSC toward H5N1, H5N2, H5N6, and H5N8 viruses. 15b demonstrated high metabolic stability, low cytotoxicity in vitro, and low acute toxicity in mice. Computational modeling and molecular dynamics studies provided insights into the role of R group of 15b in improving potency toward group-1 and -2 NAs. We believe the successful exploitation of the 150-cavity of NAs represents an important breakthrough in the development of more potent anti-influenza agents.

Discovery of Novel Pazopanib-based HDAC and VEGFR Dual Inhibitors Targeting Cancer Epigenetics and Angiogenesis Simultaneously

Herein a novel series of pazopanib hybrids as polypharmacological antitumor agents were developed based on the crosstalk between histone deacetylases (HDACs) and vascular endothelial growth factor (VEGF) pathway. Among them, one ortho-aminoanilide 6d and one hydroxamic acid 13f exhibited considerable total HDACs and VEGFR-2 inhibitory activities. The HDAC inhibitory activities endowed 6d and 13f with potent antiproliferative activities, which was not observed in the approved VEGFR inhibitor pazopanib. Compounds 6d and 13f possessed comparable HDAC isoform selectivity profiles to the clinical class I HDAC inhibitor MS-275 and the approved pan-HDAC inhibitor SAHA, respectively. 6d and 13f also exhibited uncompromised multiple tyrosine kinases inhibitory activities relative to pazopanib. The intracellular dual inhibition to HDAC and VEGFR of 6d and 13f was validated by Western blot analysis. In both HUVECs tube formation assay and rat thoracic aorta rings assay, 6d and 13f showed comparable antiangiogenic potencies to pazopanib. Whats more, 6d possessed desirable pharmacokinetic profiles with the oral bioavailability of 72% in SD rats and considerable in vivo antitumor efficacy in a human colorectal adenocarcinoma (HT-29) xenograft model.

Novel leucine ureido derivatives as aminopeptidase N inhibitors using click chemistry

The over-expression of aminopeptidase N on diverse malignant cells is associated with the tumor angiogenesis and metastasis. In this report, one new series of leucine ureido derivatives containing the triazole moiety was designed, synthesized and evaluated as APN inhibitors. Among them, compound 13v showed the best APN inhibition with an IC50 value of 0.089 ± 0.007 μM, which was two orders of magnitude lower than that of bestatin (IC50 = 9.4 ± 0.5 μM). Compound 13v also showed dose-dependent anti-angiogenesis activities. Even at the lower concentration (10 μM), compound 13v presented similar anti-angiogenesis activity compared with bestatin at 100 μM in both the human umbilical vein endothelial cells (HUVECs) capillary tube formation assay and the rat thoracic aorta rings test. Moreover, compared with bestatin, 13v exhibited comparable, if not better in vivo anti-metastasis activity in a mouse H22 pulmonary metastasis model.