ABSTRACT
We have identified and synthesized a series of imidazole containing dimerization inhibitors of inducible nitric oxide synthase (iNOS). The necessity of key imidazole and piperonyl functionality was demonstrated and SAR studies led to the identification of compound 35, which showed a dose dependant inhibition in multiple pain models, including tactile allodynia induced by spinal nerve ligation (Chung model).
Subject(s)
Enzyme Inhibitors/chemistry , Enzyme Inhibitors/therapeutic use , Hyperalgesia/drug therapy , Imidazoles/chemistry , Imidazoles/therapeutic use , Nitric Oxide Synthase Type II/antagonists & inhibitors , Pain/drug therapy , Protein Multimerization/drug effects , Animals , Enzyme Inhibitors/pharmacology , Female , Humans , Imidazoles/pharmacology , Nitric Oxide Synthase Type II/metabolism , Rats , Rats, Inbred LewABSTRACT
We report the identification of KD5170, a potent mercaptoketone-based Class I and II-histone deacetylase inhibitor that demonstrates broad spectrum cytotoxic activity against a range of human tumor-derived cell lines. KD5170 exhibits robust and sustained histone H3 hyperacetylation in HCT-116 xenograft tumors following single oral or i.v. dose and inhibition of tumor growth following chronic dosing.
Subject(s)
Antineoplastic Agents/pharmacology , Enzyme Inhibitors/pharmacology , Histone Deacetylase Inhibitors , Prodrugs/pharmacology , Pyridines/pharmacology , Sulfonamides/pharmacology , Animals , Antineoplastic Agents/chemistry , Cell Line, Tumor , Drug Screening Assays, Antitumor , HCT116 Cells , Humans , Inhibitory Concentration 50 , Mice , Mice, Nude , Molecular Structure , Prodrugs/chemistry , Pyridines/chemistry , Structure-Activity Relationship , Sulfonamides/chemistry , Xenograft Model Antitumor AssaysABSTRACT
In an effort to discover novel non-hydroxamic acid histone deacetylase (HDAC) inhibitors, a novel alpha-mercaptoketone was identified in a high-throughput screen. Lead optimization of the screening hit, led to a number of potent HDAC inhibitors. In particular, alpha-mercaptoketone 19y (KD5150) exhibited nanomolar in vitro activity and inhibition of tumor growth in vivo.
Subject(s)
Drug Screening Assays, Antitumor , Histone Deacetylase Inhibitors , Ketones/chemistry , Antineoplastic Agents/therapeutic use , Chelating Agents/pharmacology , Chemistry, Pharmaceutical , Drug Design , Enzyme Inhibitors/pharmacology , HeLa Cells , Humans , Models, Chemical , Neoplasms/drug therapy , Prodrugs/chemistry , Structure-Activity Relationship , Zinc/chemistryABSTRACT
Histone deacetylase (HDAC) inhibitors have garnered significant attention as cancer drugs. These therapeutic agents have recently been clinically validated with the market approval of vorinostat (SAHA, Zolinza) for treatment of cutaneous T-cell lymphoma. Like vorinostat, most of the small-molecule HDAC inhibitors in clinical development are hydroxamic acids, whose inhibitory activity stems from their ability to coordinate the catalytic Zn2+ in the active site of HDACs. We sought to identify novel, nonhydroxamate-based HDAC inhibitors with potentially distinct pharmaceutical properties via an ultra-high throughput small molecule biochemical screen against the HDAC activity in a HeLa cell nuclear extract. An alpha-mercaptoketone series was identified and chemically optimized. The lead compound, KD5170, exhibits HDAC inhibitory activity with an IC50 of 0.045 micromol/L in the screening biochemical assay and an EC50 of 0.025 micromol/L in HeLa cell-based assays that monitor histone H3 acetylation. KD5170 also exhibits broad spectrum classes I and II HDAC inhibition in assays using purified recombinant human isoforms. KD5170 shows significant antiproliferative activity against a variety of human tumor cell lines, including the NCI-60 panel. Significant tumor growth inhibition was observed after p.o. dosing in human HCT-116 (colorectal cancer), NCI-H460 (non-small cell lung carcinoma), and PC-3 (prostate cancer) s.c. xenografts in nude mice. In addition, a significant increase in antitumor activity and time to end-point occurred when KD5170 was combined with docetaxel in xenografts of the PC-3 prostate cancer cell line. The biological and pharmaceutical profile of KD5170 supports its continued preclinical and clinical development as a broad spectrum anticancer agent.
