Novel Clinically Relevant Proteasome Inhibitors and HDAC Inhibitors CHANDRA J1, MILLER C1, RIVERA N1 1Children’s Cancer Hospital University of Texas M.D. Anderson Cancer Center. Houston, Texas, U.S.A.
Background:Agents with specific biologic targets, that display more selective killing of leukemia cells as compared to normal lymphocytes require further study in these diseases. Here we focus on two distinct classes of new agents: proteasome inhibitors and histone deacetylase inhibitors (HDACi) and highlight a specific agent within each class as possessing unique properties with potential therapeutic benefit. NPI-0052 is a proteasome inhibitor distinct from bortezomib, which is approved by the Food and Drug Administration (FDA). PCI-24781 is an HDACi which targets a distinct class of HDAC’s more specifically than does vorinostat, the only FDA approved HDACi. Here we tested these compounds in leukemia cells to determine the mechanism of cytotoxicity and to compare them to approved counterparts.
Methods: Cell lines were representative of acute myelogenous leukemia and acute lymphocytic leukemia. Cell death was assessed by measuring DNA fragmentation by propidium iodide staining and flow cytometry. Caspase activation was measured by activity assays and by western blotting. Oxidative stress was quantitated using dichlorofluorescien and dihydroethidium to measure levels of intracellular peroxides and superoxide, respectively. Proteasome activity assays were conducted using fluorogenic peptides. Histone acetylation was assessed by western blotting for histone H3 acetylation. Combination indices were based on Chou and Talalay’s methods.
Results: Dose response and time course studies revealed that NPI-0052 is more potent than bortezomib and inhibits the catalytic activities of the proteasome more effectively than bortezomib. Similarly, PCI-24781 exerted unique effects, causing histone hyperacetylation at lower doses than vorinostat. Cells lacking caspase-8 did not display histone acetylation by PCI-24781. Surpisingly, NPI-0052 promoted histone acetylation which was dependent upon caspase-8 and oxidative stress. Synergy of NPI-0052 with several HDACi was stronger than seen with bortezomib.
Conclusions: 1) NPI-0052 is more potent alone and in combination with HDACi than bortezomib. This agent also acetylates histones in an oxidant and caspase-8 dependent manner. 2) PCI-24781 action was also dependent upon caspase-8, suggesting that promoting caspase-8 activity may complement the activity of both agents in leukemia.
Neomycin, Kanamycin and Pyranmycin: Synthesis, Antibacterial Activity and New Applications CHANG CWT Department of Chemistry and Biochemistry, Utah State University, Logan, Utah 84322, USA
Background: Antibiotic resistance represents stringent problems for the global health. Development of new antibiotic is urgent. Utilizing synthetic methodologies (glycodiversification), we have synthesized libraries of neomycin and kanamycin classes of aminoglycosides. Novel aminoglycosides with prominent antibacterial activity against a panel of resistant bacteria including Pseudomonas aeruginosa, mecilline-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE) have been identified. In addition, we have also discovered new applications of aminoglycosides. These include antifungal, antiviral and potential therapeutic for neural disease.
Methods: We employed two different synthetic strategies: 1) library construction of aminoglycosides using glycodiversification approach, and 2) leads construction using carbamate approach. Whole-cell based assay and molecular modeling have been employed for revealing useful structural activity relationship.
Results: From our studies on carbohydrates and aminoglycosides, we have made several important discoveries which can be divided into two aspects in chemistry and biology areas.
In chemistry area, we have invented several synthetic protocols to be used in the synthesis of diverse glycoconjugates of biological interest. In addition to the library synthesis of aminoglycosides, we have developed methods like dideoxygenation at mild condition, regioselective Staudinger reaction, and azido-migration for creating new structural scaffolds on aminoglycosides.
In biological area, one of the newly developed aminoglycosides, pyrankacin manifests superior activity than clinically used amikacin and gentamicin against various resistant bacteria. Two aminoglycosides exert impressive activity (low micromolar) against MRSA and VRE. In the antifungal studies, we have identified two leads with prominent activity against fungal pathogens, such as Fusarium graminearum. In the effort of developing potential therapeutics for the treatment of spinal muscular atrophy (SMA), we have noticed a lead with eminent activity in mouse model.
Conclusions: Through our continuous effort, we have developed new aminoglycosides with broad spectrum activity against resistant bacteria. Additionally, new activities and applications have also been discovered.
Competing Causes of Death from a Randomized Trial of Extended Adjuvant Endocrine Therapy for Breast Cancer: NCIC CTG MA.17 CHAPMAN JW1, MENG D1, SHEPHERD L1, PARULEKAR W1, INGLE JN2, MUSS HB3, PALMER M1, YU C1, GOSS PE4 1NCIC Clinical Trials Group, Kingston, Canada; 2Mayo Clinic, Rochester, USA;
3University of Vermont, Burlington, USA; 4Harvard University, Boston, USA.
Background: Older women with early-stage breast cancer experience higher rates of non-breast cancer-related death. We examined factors associated with cause-specific death in a large cohort of breast cancer patients treated with extended adjuvant endocrine therapy.
Methods: In the MA.17 trial conducted by the National Cancer Institute of Canada Clinical Trials Group, 5170 breast cancer patients (median age = 62 years; range = 32-94 years) who were disease-free after approximately 5 years of adjuvant tamoxifen treatment were randomly assigned to treatment with letrozole (2583 women) or placebo (2587 women). The median follow-up was 3.9 years (range = 0–7.0 years). We investigated the association of 11 baseline factors on the competing risks of death from breast cancer, other malignancies, and other causes. All statistical tests were two-sided likelihood ratio criterion tests.
Results: During follow-up, 256 deaths were reported (102 from breast cancer, 50 from other malignancies, 100 from other causes, and four from an unknown cause). Non-breast cancer deaths accounted for 60% of the 252 known deaths (72% for those ≥70 years and 48% for those <70 years). Two baseline factors were differentially associated with type of death: cardiovascular disease was associated with a statistically significant increased risk of death from other causes (P = .002) and osteoporosis was associated with a statistically significant increased risk of death from other malignancies (P = .05). An increased risk of breast cancer-specific death was associated with lymph node involvement (P<.001). Increased risk of death from all three causes was associated with older age (P<.001).
Conclusions: Non-breast cancer-related deaths were more common than breast cancer-related deaths in this cohort of 5-year cancer survivors, especially among older women.
The Antagonistic Role of Curcumin against Nicotine induced Genotoxicity on different Organs of Female Rats under Restricted Dietary Protein BANDYOPADHYAYA G1, SINHA S1, CHATTOPADHYAY K2,
CHATTOPADHYAY BD1 1Jadavpur University, Kolkata, India; 2University of Calcutta, Kolkata, India.
Background: Nicotine, a major pharmacologically active substance of tobacco for several diseases, has proven to be a potential genotoxic compound. It is absorbed through lungs with smoking and mainly metabolized in liver, yet its effect on liver injuries and other organs particularly in restricted protein diet are not clear. The aim of this study was to investigate the genotoxicity of nicotine and corresponding the protective role of curcumin on liver, ovary and uterus of female populations particularly who used tobacco but deprived of healthy diet.
Methods: The study was investigated by: 1) Measurement of total DNA concentrations and 2) Analysis of DNA damage by Comet assay in the investigated tissues of female rats maintained under altered protein diets. Two groups of female albino rats (15 animals each) were maintained in normal protein diet (18% casein) and restricted protein diet (5% casein) respectively. Each group was divided in three subgroups (5 animals each). First subgroup was served as control and second and third subgroups (experimental) was injected nicotine tartrate (2.5 mg/kg body weight/day) subcutaneously and the third subgroup was administered curcumin (80 mg/ kg body weight/day) orally. The animals were sacrificed after 21 days of treatment and the total DNA content in the specified tissues were measured. The DNA damages in the tissues were determined by Comet assay. Results were analyzed by One way Analysis of Variance, all pair wise Multiple Comparison Procedure (Holm-Sidak) and Function CORREL of Microsoft Excel.
Results: Total DNA contents of all investigated tissues were decreased more significantly (P< 0.001) by nicotine in both dietary conditions. Significant (P< 0.01) increase of total DNA content in normal diet and more significant (P<0.001) increase of that in protein restricted diet was observed due to curcumin supplementations. Curcumin more significantly (P< 0.001) reduced the DNA damage percentage of the liver tissues in protein-restricted condition.
Conclusions: 1) The degree of nicotine-induced genotoxicity increases in protein restricted condition. 2) Curcumin effectively reduces the effect of nicotine as observed in tissues. 3) The protective role of curcumin is more pronounced under protein-restricted condition.
