Kinetic assay shows that increasing red cell volume could be a treatment for sickle cell disease.

Although it has been known for more than 60 years that the cause of sickle cell disease is polymerization of a hemoglobin mutant, hydroxyurea is the only drug approved for treatment by the US Food and Drug Administration. This drug, however, is only partially successful, and the discovery of additional drugs that inhibit fiber formation has been hampered by the lack of a sensitive and quantitative cellular assay. Here, we describe such a method in a 96-well plate format that is based on laser-induced polymerization in sickle trait cells and robust, automated image analysis to detect the precise time at which fibers distort ("sickle") the cells. With this kinetic method, we show that small increases in cell volume to reduce the hemoglobin concentration can result in therapeutic increases in the delay time prior to fiber formation. We also show that, of the two drugs (AES103 and GBT440) in clinical trials that inhibit polymerization by increasing oxygen affinity, one of them (GBT440) also inhibits sickling in the absence of oxygen by two additional mechanisms.

Synthesis of novel cyclic NGR/RGD peptide analogs via on resin click chemistry.

Targeted drug deliveries as well as high resolution imaging of cancerous tissues and organs via specific cancer cell markers have become important in chemotherapeutic interventions of cancer treatment. Short peptides such as RGD and NGR are showing promising results for targeted drug delivery and in vivo imaging. We have applied on resin Huisgen's 1,3-dipolar cycloaddition to synthesize new cyclic RGD and NGR peptide analogs. Preliminary binding assays of these new analogs by fluorescence polarization indicates specific binding to purified CD13 (Aminopeptidase N) and cell lysates from MCF-7 and SKOV-3 cancer cell lines.

Screening a panel of drugs with diverse mechanisms of action yields potential therapeutic agents against neuroblastoma.

Neuroblastoma (NB) is the most common extracranial solid tumor in children. Despite current aggressive therapy, the survival rate for high risk NB remains less than 40%. To identify novel effective chemo-agents against NB, we screened a panel of 96 drugs against two NB cell lines, SK-N-AS and SH-SY5Y. We found 30 compounds that were active against NB cell lines at < or =10 microM concentration. More interestingly, 17 compounds are active at < or =1 microM concentration, and they act through a wide spectrum of diverse mechanisms such as mitotic inhibition, topoisomerase inhibition, targeting various biological pathways, and unknown mechanisms. The majority of these active compounds also induced caspase 3/7 by more than 2-fold. Of these 17 active compounds against NB cell lines at sub-micromolar concentration, eleven compounds are not currently used to treat NB. Among them, nine are FDA approved compounds, and three agents are undergoing clinical trials for various malignancies. Furthermore, we identified four agents active against these NB cell lines that have not yet been tested in the clinical setting. Finally we demonstrated that Cucurbitacin I inhibits neuroblastoma cell growth through inhibition of STAT3 pathway. These drugs thus represent potential novel therapeutic agents for patients with NB, and further validation studies are needed to translate them to the clinic.

Synthesis of natural product-inspired inhibitors of Mycobacterium tuberculosis mycothiol-associated enzymes: the first inhibitors of GlcNAc-Ins deacetylase.

Synthesis and evaluation of a chemical library of inhibitors of the mycothiol biosynthesis enzyme GlcNAc-Ins deacetylase (MshB) and the mycothiol-dependent detoxification enzyme mycothiol- S-conjugate amidase (MCA) from Mycobacterium tuberculosis are reported. The library was biased to include structural features of a group of natural products previously shown to competitively inhibit MCA. Molecular docking studies that reproducibly placed the inhibitors in the active site of the enzyme MshB reveal the mode of binding and are consistent with observed biological activity.

Design and synthesis of substrate-mimic inhibitors of mycothiol-S-conjugate amidase from Mycobacterium tuberculosis.

The Staudinger reaction between a polymer-supported triphenylphosphine reagent and pseudo-disaccharide azides is successfully applied to synthesize a variety of substrate-mimic mycothiol analogs. Screening of this new group of analogs against the mycobacterial detoxification enzyme mycothiol-S-conjugate amidase (MCA) yielded several modest inhibitors (IC50 values around 50 microM) and provided additional structure-activity relationships for future optimization of inhibitors of MCA and its homologs.