ABSTRACT
Histone deacetylases (HDACs) are overexpressed in various types of primary human cancer and have become attractive targets for cancer therapy. We designed and synthesized a series of new class of HDAC inhibitors (HDACi). Among these, S-(E)-3-(1-(1-(benzo[d]oxazol-2-yl)-2-methylpropyl)-1H-1,2,3-triazol-4-yl)-N-hydroxyacrylamide (NK-HDAC-1) showed potent antitumor activity. In the present study, we examined the antitumor effects of NK-HDAC-1 on breast cancer in vitro and in vivo. The inhibitory effects of NK-HDAC-1 on HDAC enzyme activity and cell growth were more potent compared to suberoylanilide hydroxamic acid (SAHA). NK-HDAC-1 caused G1 cell cycle arrest at concentrations below 0.2 µM and G2/M arrest at concentrations above 0.4 µM through p21 upregulation and cyclin D1 downregulation. NK-HADC-1 induced hyperacetylation of histone H3 and H4 around the promoter region of p21. NK-HDAC-1 promoted apoptosis in MDA-MB-231 breast cancer cells by activating both the intrinsic and the extrinsic pathway NK-HDAC-1 at doses of 3, 10 and 30 mg/kg reduced the tumor volume in MDA-MB-231 xenografts by 25.9, 48.8 and 63.6%, respectively. The results suggested that NK-HDAC-1 may be a promising therapeutic candidate in treating human breast cancer.
Subject(s)
Benzoxazoles/pharmacology , Breast Neoplasms/drug therapy , Histone Deacetylase Inhibitors/pharmacology , Hydroxamic Acids/pharmacology , Animals , Apoptosis/drug effects , Benzoxazoles/adverse effects , Cell Line, Tumor , Cell Proliferation/drug effects , Cyclin D1/biosynthesis , Down-Regulation , Female , G1 Phase Cell Cycle Checkpoints/drug effects , G2 Phase Cell Cycle Checkpoints/drug effects , Humans , Hydroxamic Acids/adverse effects , Male , Mice , Mice, Inbred BALB C , Neoplasm Transplantation , Up-Regulation , Vorinostat , Xenograft Model Antitumor AssaysABSTRACT
Herein, further SAR studies of lead compound NSC746457 (Shen, J.; Woodward, R.; Kedenburg, J. P.; Liu, X. W.; Chen, M.; Fang, L. Y.; Sun; D. X.; Wang. P. G. J. Med. Chem. 2008, 51, 7417-7427) were performed, including the replacement of the trans-styryl moiety with a 2-substituted benzo-hetero aromatic ring and the introduction of a substituent onto the central methylene carbon. A promising chiral lead, S-(E)-3-(1-(1-(benzo[d]oxazol-2-yl)-2-methylpropyl)-1H-1,2,3-triazol-4-yl)-N-hydroxyacrylamide (12, NK-HDAC-1), was discovered and showed about 1 order of magnitude more potency than SAHA in both enzymatic and cellular assays. For the in vitro safety tests, NK-HDAC-1 was far less toxic to nontransformed cells than tumor cells and showed no significant inhibition activity against CYP-3A4. The pharmaceutical properties (LogD, solubility, liver micrsomal stability (t1/2), plasma stability (t1/2), and apparent permeability) strongly suggested that NK-HDAC-1 might be superior to SAHA in bioavailability and in vivo half-life.
Subject(s)
Antineoplastic Agents/chemical synthesis , Benzoxazoles/chemical synthesis , Histone Deacetylase Inhibitors/chemical synthesis , Hydroxamic Acids/chemical synthesis , Triazoles/chemical synthesis , Animals , Antineoplastic Agents/chemistry , Antineoplastic Agents/pharmacology , Benzoxazoles/chemistry , Benzoxazoles/pharmacology , Caco-2 Cells , Cell Line, Tumor , Click Chemistry , Cytochrome P-450 CYP3A , Cytochrome P-450 CYP3A Inhibitors , Drug Screening Assays, Antitumor , Histone Deacetylase 2/chemistry , Histone Deacetylase Inhibitors/chemistry , Histone Deacetylase Inhibitors/pharmacology , Humans , Hydroxamic Acids/chemistry , Hydroxamic Acids/pharmacology , In Vitro Techniques , Mice , Microsomes, Liver/metabolism , Models, Molecular , Permeability , Solubility , Stereoisomerism , Structure-Activity Relationship , Triazoles/chemistry , Triazoles/pharmacologyABSTRACT
Previously, we reported a click-chemistry based approach to the synthesis of a novel class of histone deacetylase (HDAC) inhibitors [1]. The lead compound NSC746457 was found to be as potent as SAHA (Vorinostat). Further optimization of NSC746457 by using the HDAC2-TSA crystal structure is described herein. Docking of NSC746457 into HDAC2 binding domain suggested that the hydrophobic residue Phe210 flanking the cap-group binding-motif could be exploited for structural optimization. Substitution on the methylene group of cinnamic cap region led to identification of more potent HDAC inhibitors: isopropyl derivative 5 and tert-butyl derivative 6, with an IC(50) value of 22 nM and 18 nM, respectively.
Subject(s)
Antineoplastic Agents/chemical synthesis , Cell Proliferation/drug effects , Histone Deacetylase 1/chemistry , Histone Deacetylase 2 , Histone Deacetylase Inhibitors/chemical synthesis , Hydroxamic Acids/chemical synthesis , Neoplasms/enzymology , Triazoles/chemical synthesis , Antineoplastic Agents/pharmacology , Binding Sites , Cell Line, Tumor , Click Chemistry , Crystallography, X-Ray , Drug Design , Drug Screening Assays, Antitumor , Histone Deacetylase 1/metabolism , Histone Deacetylase 2/chemistry , Histone Deacetylase 2/metabolism , Histone Deacetylase Inhibitors/pharmacology , Humans , Hydrophobic and Hydrophilic Interactions , Hydroxamic Acids/pharmacology , Models, Molecular , Neoplasms/drug therapy , Neoplasms/pathology , Phenylalanine/chemistry , Phenylalanine/metabolism , Protein Binding , Protein Structure, Secondary , Structure-Activity Relationship , Triazoles/pharmacology , VorinostatABSTRACT
PURPOSE: The histone deacetylase inhibitor (HDACi) suberoylanilide hydroxamic acid (SAHA) enhances taxol-induced antitumor effects against some human cancer cells. The aim of this study is to investigate whether SAHA can enhance taxol-induced cell death against human breast cancer cells and to illustrate the mechanism in detail. METHODS: A panel of eight human breast cancer cell lines and an immortalized human breast epithelial cell line were used to determine the inhibitory effects of SAHA, taxol, or their combination by MTT assay. The effects of SAHA with or without taxol on cell cycle distributions, apoptosis, and protein expressions were also examined. The inhibitory effects on tumor growth were characterized in vivo in BALB/c nude mice bearing a breast cancer xenograft model. RESULTS: Taxol-resistant and multi-resistant breast cancer cells were as sensitive to SAHA as taxol-sensitive breast cancer cells. A dose-dependent synergistic growth inhibition was found in all the tested breast cancer cell lines treated with the SAHA/taxol combinations. The synergetic effect was also observed in the in vivo xenograft tumor model. The cell cycle analysis and apoptosis assay showed that the synergistic effects resulted from enhanced G2/M arrest and apoptosis. CONCLUSIONS: SAHA increased the anti-tumor effects of taxol in breast cancer in vitro and in vivo. The combination of SAHA and taxol may have therapeutic potential in the treatment of breast cancer.
