Minor structural modifications to Pracinostat produce big changes in its biological responses.

A series of compounds similar to Pracinostat that contained benzimidazole ring and N-hydroxyacrylamide attached at 5- or 6-position were designed, synthesized, and evaluated as HDAC inhibitors. It was interesting to find that the corresponding derivative 1 with N-hydroxyacrylamide attached at 5-position was a potent HDAC inhibitor while the others at 6-position were not. This is the first time to demonstrate the position difference plays important role in the HDAC inhibitory activities of the cinnamic hydroxamates.

Macrocyclic compounds as anti-cancer agents: design and synthesis of multi-acting inhibitors against HDAC, FLT3 and JAK2.

A novel series of macrocyclic compounds were designed and synthesized as multi-target inhibitors targeting HDAC, FLT3 and JAK2. Some of these compounds exhibited potent HDAC inhibition as well as FLT3 and JAK2 inhibition under both cell-free and cellular conditions. In vitro antiproliferative assay indicated that these compounds were interestingly more cytotoxic to MV4-11 cells bearing FLT3-ITD mutation and HEL cells bearing JAK2(V617F) mutation.

Design, synthesis and biological evaluation of di-substituted cinnamic hydroxamic acids bearing urea/thiourea unit as potent histone deacetylase inhibitors.

A novel class of di-substituted cinnamic hydroxamic acid derivatives containing urea or thiourea unit was designed, synthesized and evaluated as HDAC inhibitors. All tested compounds demonstrated significant HDAC inhibitory activities and anti-proliferative effects against diverse human tumor cell lines. Among them, 7l exhibited most potent pan-HDAC inhibitory activity, with an IC50 value of 130 nM. It also showed strong cellular inhibition against diverse cell lines including HCT-116, MCF-7, MDB-MB-435 and NCI-460, with GI50 values of 0.35, 0.22, 0.51 and 0.48 µM, respectively.

[Research progresses of the PARP inhibitors for the treatment of cancer].

The poly(ADP-ribose) polymerases (PARPs) is an important group of enzymes in DNA repair pathways, especially the base excision repair (BER) for DNA single-strand breaks (SSBs) repair. Inhibition of PARP in DNA repair-defective tumors (like those with BRAC1/2 mutations) can lead to cell death and genomic instability, what is so called "synthetic lethality". Currently, PARP inhibitors combined with cytotoxic chemotherapeutic agents in the treatment of BRCA-1/2 deficient cancers are in the clinical development. In this review, we will be focused on the development of combination application of PARP inhibitors with other anticancer agents in clinical trials.

Design, synthesis and biological evaluation of indeno[1,2-d]thiazole derivatives as potent histone deacetylase inhibitors.

Novel indeno[1,2-d]thiazole hydroxamic acids were designed, synthesized, and evaluated for histone deacetylases (HDACs) inhibition and antiproliferative activities on tumor cell lines. Most of the tested compounds exhibited HDAC inhibition and antiproliferative activity against both MCF7 and HCT116 cells with GI50 values in the sub-micromolar range. Among them, compound 6o showed good inhibitory activity against pan-HDAC with IC50 value of 0.14 µM and significant growth inhibition on MCF7 and HCT116 cells with GI50 values of 0.869 and 0.535 µM, respectively.

Discovery and mechanism study of SIRT1 activators that promote the deacetylation of fluorophore-labeled substrate.

SIRT1 is an NAD(+)-dependent deacetylase, whose activators have potential therapeutic applications in age-related diseases. Here we report a new class of SIRT1 activators. The activation is dependent on the fluorophore labeled to the substrate. To elucidate the activation mechanism, we solved the crystal structure of SIRT3/ac-RHKK(ac)-AMC complex. The structure revealed that the fluorophore blocked the H-bond formation and created a cavity between the substrate and the Rossmann fold. We built the SIRT1/ac-RHKK(ac)-AMC complex model based on the crystal structure. K(m) and K(d) determinations demonstrated that the fluorophore decreased the peptide binding affinity. The binding modes of SIRT1 activators indicated that a portion of the activators interacts with the fluorophore through π-stacking, while the other portion inserts into the cavity or interacts with the Rossmann fold, thus increasing the substrate affinity. Our study provides new insights into the mechanism of SIRT1 activation and may aid the design of novel SIRT1 activators.

Discovery of (2E)-3-{2-butyl-1-[2-(diethylamino)ethyl]-1H-benzimidazol-5-yl}-N-hydroxyacrylamide (SB939), an orally active histone deacetylase inhibitor with a superior preclinical profile.

A series of 3-(1,2-disubstituted-1H-benzimidazol-5-yl)-N-hydroxyacrylamides (1) were designed and synthesized as HDAC inhibitors. Extensive SARs have been established for in vitro potency (HDAC1 enzyme and COLO 205 cellular IC(50)), liver microsomal stability (t(1/2)), cytochrome P450 inhibitory (3A4 IC(50)), and clogP, among others. These parameters were fine-tuned by carefully adjusting the substituents at positions 1 and 2 of the benzimidazole ring. After comprehensive in vitro and in vivo profiling of the selected compounds, SB939 (3) was identified as a preclinical development candidate. 3 is a potent pan-HDAC inhibitor with excellent druglike properties, is highly efficacious in in vivo tumor models (HCT-116, PC-3, A2780, MV4-11, Ramos), and has high and dose-proportional oral exposures and very good ADME, safety, and pharmaceutical properties. When orally dosed to tumor-bearing mice, 3 is enriched in tumor tissue which may contribute to its potent antitumor activity and prolonged duration of action. 3 is currently being tested in phase I and phase II clinical trials.

[The signal transduction pathway of multi-target kinase inhibitors as anticancer agents in clinical use or in phase III].

Signal transduction in cells plays an important role in the process of cellular metabolism, segmentation, differentiation, biological behaviors and cell death. Direct and indirect involvement of kinases in tumor growth, metastasis and apoptosis make them the most promising targets for anticancer discovery. Most of the kinase inhibitors in clinical use or in late development stages are multi-target kinase inhibitors (MTKIs). These MTKIs are demonstrated to exert potent anti-tumor effects through several different pathways. This review presents in the view of a medicinal chemistry point, a brief account and analysis of transduction pathways of representative MTKIs in clinical use or in late development stages.

N-Hydroxy-1,2-disubstituted-1H-benzimidazol-5-yl acrylamides as novel histone deacetylase inhibitors: design, synthesis, SAR studies, and in vivo antitumor activity.

A series of N-hydroxy-1,2-disubstituted-1H-benzimidazol-5-yl acrylamides were designed and synthesized as novel HDAC inhibitors. General SAR has been established for the substituents at positions 1 and 2, as well as the importance of the ethylene group and its attachment to position 5. Optimized compounds are much more potent than SAHA in both enzymatic and cellular assays. A representative compound, 23 (SB639), has demonstrated antitumor activity in a colon cancer xenograft model.

[Structure-activity relationships of histone deacetylase inhibitors].

Among those enzymes that regulate gene expression, histone deacetylases (HDACs) play important roles in cell cycles. Extensive studies were carried out in the field of HDACs and the applications of HDAC inhibitors (HDACIs) as chemotherapeutic interventions for diverse diseases. HDACIs have moved from laboratories to clinic uses. Huge bodies of related research results were well documented and dispersed in literature. According to our understanding, HDACIs can be broadly classified as hydroxamic acids, cyclic tetrapeptides, short chain fatty acids, benzamides and electrophilic ketones. Herein, we are going to review the design and their structure-activity relationships of HDACIs and according to their structural catalogs.

Anticancer drug discovery targeting DNA hypermethylation.

DNA methyltransferases (DNMTs) are important regulators of gene transcription and their roles in carcinogenesis have been a topic of considerable interest in the last few years. Diverse classes of chemical compounds including nucleotide analogues, adenosine analogues, aminobenzoic derivatives, polyphenols, hydrazines, phthalides, disulfides and antisenses are being discovered and evaluated as DNMT inhibitors targeting DNA hypermethylation. Among them, 5-Azacytidine 5 and Decitabine 6 were launched recently. Several other compounds are under clinical trials. Some of these compounds were discovered from structure-based drug design. These compounds exert their DNA methylation inhibitory by different mechanisms. This review will present a brief account of various DNA methyltransferases and their biological functions, with focus on actuality of design and synthesis of various inhibitors of DNA hypermethylation as anticancer drugs.