Abstract 2493
Prognosis for acute myelogenous leukemia (AML) with traditional chemotherapeutic agents remains poor, most patients relapse and die of their disease. Studies have shown that AML can be ...originated and maintained by leukemia stem cells (LSCs) and that a high percentage of phenotypically-defined LSCs correlate to especially poor prognosis. Thus, novel therapies that can eliminate LSCs are needed. Upregulation of HSP70 has been described in human cancer cells and is often associated with chemoresistance and poor prognosis. Therefore, HSP70 represents a novel target for cancer therapy. Due to this, we tested a novel inhibitor of tumor-HSP70, YK5, and found that it can induce potent cell death in AML cells including progenitor and stem cell populations with minimal effects in normal hematopoietic cells.
Fifteen primary AML patient samples were treated with YK5 in varying concentrations for 48 hours to determine the LD50 of YK5. The viability of these samples was determined by multiparameter flow cytometry using cell surface markers to distinguish, lymphocytes, blasts, progenitor and stem cell populations in conjunction with Annexin V and 7AAD. Mean LD50 for all samples tested was 4.5μM (CI 95% 2.239–6.853). Three of these samples had very low LD50s below 2.5μM and only one sample demonstrated relative resistance with a LD50 that was greater than 15μM. Notably, progenitor and stem cell populations were also targeted while normal remaining lymphocytes were spared. Furthermore, we found that LSCs in a subset of patient samples treated with YK5 exhibited higher sensitivity to the compound when compared to blast cells. Importantly, treatment of primary AML samples with 5μM YK5 resulted in a 63% decrease in colony forming ability when compared to untreated control (N=5), suggesting that YK5 can impair malignant progenitors. In contrast, normal CD34+ cord blood cells after treatment with 5μM YK5 for 48hrs exhibited a viability of 57% (N=3). Xenotransplant assays are currently ongoing to determine the ability of YK5 to inhibit LSC function. Treatment with YK5 resulted in a decrease in phosphorylation of STAT5, determined by flow cytometry. Taken together, HSP70 inhibition is a promising potential treatment for AML and has the potential to eradicate leukemic stem and progenitor cells while sparing normal hematopoietic cells. Thus, targeting HSP70 in AML appears to hold great promise.
*JFR and KKS contributed equally to this project
Roboz:EpiCept: Consultancy; ChemGenex: Consultancy; Celgene: Consultancy; Boehringer Ingelheim: Consultancy.
The use of simple calix4arenes for chemical conversion of NO2/N2O4 gases is demonstrated in solution and in the solid state. Upon reacting with these gases, calixarenes 1 encapsulate nitrosonium ...(NO+) cations within their cavities with the formation of stable calixarene–NO+ complexes 2. These complexes act as encapsulated nitrosating reagents; cavity effects control their reactivity and selectivity. Complexes 2 were effectively used for nitrosation of secondary amides 5, including chiral derivatives. Unique size–shape selectivity was observed, allowing for exclusive nitrosation of less crowded N‐Me amides 5 a–e (up to 95 % yields). Bulkier N‐Alk (Alk>Me) substrates 5 did not react due to the hindered approach to the encapsulated NO+ reagents. Robust, silica gel based calixarene material 3 was prepared, which reversibly traps NO2/N2O4 with the formation of NO+‐storing silica gel 4. With material 4, similar size–shape selectivity was observed for nitrosation. The N‐Me–N‐nitroso derivatives 6 d,e were obtained with ∼30 % yields, while bulkier amides were nitrosated with much lower yields (<8 %). Enantiomerically pure encapsulating reagent 2 d was tested for nitrosation of racemic amide 5 t, showing modest but reproducible stereoselectivity and ∼15 % ee. Given high affinity to NO+ species, which can be generated by a number of NOX gases, these supramolecular reagents and materials may be useful for NOX entrapment and separation in the environment and biomedical areas.
Toxic and aggressive environmental gases NOX can be converted into mild and selective reagents for organic synthesis! Simple calix4arenes reversibly react with NO2/N2O4 gases with the formation of stable calix–nitrosonium complexes. These are encapsulated reagents. Their reactivity and selectivity is controlled through the cavity effects.
Abstract
The use of simple calix4arenes for chemical conversion of NO
2
/N
2
O
4
gases is demonstrated in solution and in the solid state. Upon reacting with these gases, calixarenes
1
encapsulate ...nitrosonium (NO
+
) cations within their cavities with the formation of stable calixarene–NO
+
complexes
2
. These complexes act as encapsulated nitrosating reagents; cavity effects control their reactivity and selectivity. Complexes
2
were effectively used for nitrosation of secondary amides
5
, including chiral derivatives. Unique size–shape selectivity was observed, allowing for exclusive nitrosation of less crowded
N
‐Me amides
5 a
–
e
(up to 95 % yields). Bulkier
N
‐Alk (Alk>Me) substrates
5
did not react due to the hindered approach to the encapsulated NO
+
reagents. Robust, silica gel based calixarene material
3
was prepared, which reversibly traps NO
2
/N
2
O
4
with the formation of NO
+
‐storing silica gel
4
. With material
4
, similar size–shape selectivity was observed for nitrosation. The
N
‐Me–
N
‐nitroso derivatives
6 d
,
e
were obtained with ∼30 % yields, while bulkier amides were nitrosated with much lower yields (<8 %). Enantiomerically pure encapsulating reagent
2 d
was tested for nitrosation of racemic amide
5 t
, showing modest but reproducible stereoselectivity and ∼15 %
ee
. Given high affinity to NO
+
species, which can be generated by a number of NO
X
gases, these supramolecular reagents and materials may be useful for NO
X
entrapment and separation in the environment and biomedical areas.
Heat shock protein 70 (Hsp70) is a chaperone protein that helps protect against cellular stress, a function that may be co-opted to fight human diseases. In particular, the upregulation of Hsp70 can ...suppress the neurotoxicity of misfolded proteins, suggesting possible therapeutic strategies in neurodegenerative diseases. Alternatively, in cancer cells where high levels of Hsp70 inhibit both intrinsic and extrinsic apoptotic pathways, a reduction in Hsp70 levels may induce apoptosis. To evaluate and identify, in a single assay format, small molecules that induce or inhibit endogenous Hsp70, we have designed and optimized a microtiter assay that relies on whole-cell immunodetection of Hsp70. The assay utilizes a minimal number of neuronal or cancer cells, yet is sufficiently sensitive and reproducible to permit quantitative determinations. We further validated the assay using a panel of Hsp70 modulators. In conclusion, we have developed an assay that is fast, robust, and cost efficient. As such, it can be implemented in most research laboratories. The assay should greatly improve the speed at which novel Hsp70 inducers and inhibitors of expression can be identified and evaluated.
Supramolecular chemistry has been defined as "chemistry beyond molecules", and involves investigating molecular systems held together reversibly by intermolecular forces, not by covalent bonds. This ...dissertation discusses a supramolecular approach towards sensing, entrapment and utilization of NO2/N 2O4 gases. Chapter 1 briefly discusses supramolecular chemistry and supramolecular chemistry of gases. In chapter 2, the interaction of NOx with metalloporphyrins is described. Specifically, ruthenium nitrosyl derivatives hold a special place in mimicking biorelevant NO-metal interactions. A previously unnoticed reaction between NO2/N2O4 and a Ru(II) porphyrin is described. It causes disproportionation of N2O 4 and leads to a stable nitrosyl nitrato complex. Our findings offer a new insight into the mechanism of sensing and fixation of NO2/N 2O4 by metalloporphyrins. In chapter 3, the reaction between calixarenes and NO2/N 2O4 gases was investigated. Exposure of tetra-O-alkylated cone or 1,3-alternate calix4arenes to NO 2/N2O4, both in chloroform solution and in the solid state, resulted in deeply colored calixarene-nitrosonium (NO +) complexes. In the presence of a Lewis acid, such as SnCl4 , stable calixarene-NO+ complexes were isolated in a quantitative yield and fully characterized. NO+ is found encapsulated within the calixarene cavity, and forms a stable charge-transfer complex. The NO+ encapsulation was also demonstrated in titration experiments with calixarenes and NO+SbF6- salt in chloroform. The complexation process is reversible, and the complexes dissociate upon addition of water and alcohol, recovering the parent calixarenes. Chapter 4 describes the polymer supported calixarenes. Functionalized calix4arenes were synthesized and attached to silica gels and polyethyleneglycol (PEG), which afforded solid materials capable of visual detection and entrapment of NO2/N2O4 both in the solid state and solution. The concept of encapsulated nitrosating reagent was introduced in chapter 5. Stable calixarene-NO+ complexes act as encapsulated nitrosating reagents; cavity effects control their reactivity and selectivity. They were effectively used for nitrosation of secondary amides. Unique size-shape selectivity was observed, allowing for favorable nitrosation of only less crowded N-Me amides. For robust, silica gel and PEG based calixarene materials, similar size-shape selectivity was observed. Enantiomerically pure encapsulating reagents were tested for nitrosation of racemic amide, showing modest but reproducible stereoselectivity.
In situ strain photoluminescence （PL） and Raman spectroscopy have been employed to exploit the evolutions of the electronic band structure and lattice vibrational responses of chemical vapor ...deposition （CVD）-grown monolayer tungsten disulphide （WS2） under uniaxial tensile strain. Observable broadening and appearance of an extra small feature at the longer-wavelength side shoulder of the PL peak occur under 2.5% strain, which could indicate the direct-indirect bandgap transition and is further confirmed by our density-functional-theory calculations. As the strain increases further, the spectral weight of the indirect transition gradually increases. Over the entire strain range, with the increase of the strain, the light emissions corresponding to each optical transition, such as the direct bandgap transition （K-K） and indirect bandgap transition （F-K, ≥2.5%）, exhibit a monotonous linear redshift. In addition, the binding energy of the indirect transition is found to be larger than that of the direct transition, and the slight lowering of the trion dissociation energy with increasing strain is observed. The strain was used to modulate not only the electronic band structure but also the lattice vibrations. The softening and splitting of the in-plane E＇ mode is observed under uniaxial tensile strain, and polarization-dependent Raman spectroscopy confirms the observed zigzag-oriented edge of WS2 grown by CVD in previous studies. These findings enrich our understanding of the strained states of monolayer transition-metal dichalcogenide （TMD） materials and lay a foundation for developing applications exploiting their strain-dependent optical properties, including the strain detection and light-emission modulation of such emerging two-dimensional TMDs.
Hsp70s are important cancer chaperones that act upstream of Hsp90 and exhibit independent anti-apoptotic activities. To develop chemical tools for the study of human Hsp70, we developed a homology ...model that unveils a previously unknown allosteric site located in the nucleotide binding domain of Hsp70. Combining structure-based design and phenotypic testing, we discovered a previously unknown inhibitor of this site, YK5. In cancer cells, this compound is a potent and selective binder of the cytosolic but not the organellar human Hsp70s and has biological activity partly by interfering with the formation of active oncogenic Hsp70/Hsp90/client protein complexes. YK5 is a small molecule inhibitor rationally designed to interact with an allosteric pocket of Hsp70 and represents a previously unknown chemical tool to investigate cellular mechanisms associated with Hsp70.
Display omitted
•Homology model of human Hsp70 unveils a druggable allosteric site•YK5, a selective binder of the allosteric site, is identified by rational design•YK5 has activity in cancer cells partly by altering the Hsp70/Hsp90 complex•The effect of YK5 on Hsp70/Hsp90 complexes is uncoupled from HSF-1
Hsp70s are important cancer proteins. Rodina et al. unveil an allosteric site located in Hsp70’s nucleotide binding domain, which they use for the rational design of YK5, a selective and potent Hsp70 binder with retained cellular activity. YK5 is a promising chemical tool to investigate Hsp70 associated mechanisms.
Molecular Containers for NO X Gases Rudkevich, Dmitry M.; Kang, Yanlong; Leontiev, Alexander V. ...
Supramolecular chemistry,
20/1/1/, Volume:
17, Issue:
1-2
Journal Article
Peer reviewed
Supramolecular approaches to visual detection, storage, conversion and use of NO
X
gases are described that deploy calixarenes and their derivatives, such as hemicarcerands and synthetic nanotubes. ...Polymer-supported calixarene materials for NO
X
are also introduced. Chemical fixation of NO
2
/N
2
O
4
is demonstrated through the transformation into calixarene-NO
+
complexes and their use as nitrosonium storing and releasing reagents for organic synthesis. These findings highlight perspectives of supramolecular chemistry and molecular recognition in sensing and fixation of environmentally important gases.
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