Synthesis and biological study of class I selective HDAC inhibitors with NO releasing activity.

Based on the multi-mechanism antitumor strategy and the regulatory effect of nitric oxide (NO) on histone deacetylases (HDACs), a series of N-acyl-o-phenylenediamine-based HDAC inhibitors equipped with the phenylsulfonylfuroxan module as NO donor was designed, synthesized and biologically evaluated. The in vitro HDAC inhibitory assays revealed that compared with the clinical class I selective HDAC inhibitor MS275, compounds 7c, 7d and 7e possessed similar HDAC inhibitory potency and selective profile, which were confirmed by the results of western blot analysis. The western blot analysis also showed that NO scavenger N-acetyl cysteine (NAC) could weaken the intracellular HDAC inhibitory ability of compound 7c, supporting the HDAC inhibitory effect of NO generated by 7c. It is worth noting that compounds 7c, 7d and 7e exhibited more potent in vitro antiproliferative activities than MS275 against all four tested solid tumor cell lines. The promising in vivo antitumor potency of 7c was demonstrated in a HCT116 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 ±â€¯0.007 µM, which was two orders of magnitude lower than that of bestatin (IC50 = 9.4 ±â€¯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.

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.

Discovery of meta-sulfamoyl N-hydroxybenzamides as HDAC8 selective inhibitors.

In the past decade, although research and development of histone deacetylase (HDAC) inhibitors as therapeutic agents have achieved great accomplishments, especially in oncology field, there is still an urgent need for the discovery of isoform-selective HDAC inhibitors considering the side effects caused by nonselective HDAC inhibitors. HDAC8, a unique class I zinc-dependent HDAC, is becoming a potential target in cancer and other diseases. In the current study, a novel series of N-hydroxy-3-sulfamoylbenzamide-based HDAC8 selective inhibitors (12a-12p) were designed and synthesized, among which compounds 12a, 12b and 12c exhibited potent HDAC8 inhibition with two-digit nanomolar IC50 values, and considerable selectivity over HDAC2 (>180-fold) and HDAC6 (∼30-fold) which was confirmed by western blot analysis. It is worth noting that 12a, 12b and 12c displayed highly selective anti-proliferative activity to T-cell leukemia cell lines Jurkat, Molt-4 and neuroblastoma cell line SK-N-BE-(2). Such selective cytotoxicity was also observed in the well-known HDAC8 selective inhibitor PCI-34051 but not in the pan-HDAC inhibitors SAHA and PXD101, indicating that HDAC8 selective inhibitor should have preferable benefit-risk profile in comparison with pan-HDAC inhibitor. Finally, the HDAC8 selectivity of 12a, 12b and 12c was rationalized by molecular docking study.

Nitric oxide donor hybrid compounds as promising anticancer agents.

Nitric oxide (NO) plays important roles in cardiovascular regulation, nerve transmission delivery and immune responses. In the last semicenturry, it has been proved that though low concentration of NO is tumor-promoting, high concentration of NO could exhibit multiple antitumor effects, which led to the research and development of kinds of NO donors and NO donor hybrid compounds as antitumor agents. Herein, the recent development of NO donor hybrid compounds is briefly reviewed.

Selective HDAC inhibitors with potent oral activity against leukemia and colorectal cancer: Design, structure-activity relationship and anti-tumor activity study.

Previously, we reported the discovery of a series of N-hydroxycinnamamide-based HDAC inhibitors, among which compound 11y exhibited high HDAC1/3 selectivity. In this current study, structural derivatization of 11y led to a new series of benzamide based HDAC inhibitors. Most of the compounds exhibited high HDACs inhibitory potency. Compound 11a (with 4-methoxybenzoyl as N-substituent in the cap and 4-(aminomethyl) benzoyl as the linker group) exhibited selectivity against HDAC1 to some extent, and showed potent antiproliferative activity against several tumor cell lines. In vivo studies revealed that compound 11a displayed potent oral antitumor activity in both hematological tumor cell U937 xenograft model and solid tumor cell HCT116 xenograft model with no obvious toxicity. Further modification of benzamide 3, 11a and 19 afforded new thienyl and phenyl compounds (50a, 50b, 63a, 63b and 63c) with dramatic HDAC1 and HDAC2 dual selectivity, and the fluorine containing compound 56, with moderate HDAC3 selectivity.