Molecular targeting in acute myeloid leukemia (AML) therapy: APcK110 is a new inhibitor of c-Kit activity in AML blasts

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Background: Tyrosine kinases (TK) are important for most cellular functions and require stringent control and regulation. C- Kit, a TK and transmembrane receptor for stem cell factor, plays a crucial role in hematopoiesis. Mutations of c-Kit can contribute to AML pathophysiology and have been associated with shorter survival and higher relapse risk following standard AML therapy. On the other hand, responses have been observed following TK inhibitor therapy such as imatinib. Identification of c-Kit or its pathways in AML leukemogenesis and development of new compounds targeting these mutations may therefore hold promise for therapy. Methods: APcK110 is the result of a structure-based design of c-Kit inhibitors and was derived of a set of compounds with favorable IC50 values in a c-Kit kinase assay. Here we present results of the activity and mechanism of action of APcK110. We used the mastocytosis cell line HMC1.1 carrying an activating c-Kit mutation and two AML lines (OCIM2 and OCI/AML3) as well as primary samples from patients with AML. Results: We demonstrate that: (1) APcK110 inhibits proliferation of all three cell lines in a dose dependent fashion using an MTT assay. Inhibition of proliferation is most significant in the SCF-dependent cell line OCI/AML3; (2) inhibition of OCIM2 cells (SCF-responsive) by APcK110 can be enhanced when adding SCF suggesting recruitment of c-Kit-dependent signaling components and increased activity of the c-Kit inhibitor under these circumstances; (3) APcK110 is a more potent inhibitor of OCI/AML3 proliferation than imatinib and dasatininb; (4) using Western immunoblotting, APcK110 decreases levels of phospho-Akt, phospho-Stat3 and 5 in a time- and dose-dependent fashion demonstrating activity of APcK110 on c-Kit downstream signaling pathways; (5) APcK110 induces apoptosis by cleavage of caspase 3 and PARP; (6) APcK110 inhibits proliferation of primary AML cells in a clonogenic assay, but does not affect proliferation of normal controls. Conclusions: APcK110 is a potent inhibitor of AML cell lines and primary samples from patients with AML. Activation of c-Kit or downstream pathways increases activity of APcK110. APcK110 and similar compounds should be evaluated in clinical trials of patients with AML.

No significant financial relationships to disclose.

Novel cytokine peptide-based vaccines: an interleukin-4 vaccine suppresses airway allergic responses in mice

BACKGROUND

Monoclonal antibodies or soluble receptors have been used to block over-produced endogenous cytokines. However, they have disadvantages of short half-lives, high costs, and possible adverse effects. Using interleukin (IL)-4 as a model target, we sought to develop a novel therapeutic strategy by constructing an IL-4 peptide-based vaccine for blocking IL-4 on a persistent basis, and to evaluate its efficacy in a mouse model of asthma.

METHODS

A peptide was selected by antigenic prediction and structure analysis of IL-4/receptor complex. The vaccine was constructed by employing truncated hepatitis B core antigen as carrier with the peptide inserted using gene engineering methods. It was then expressed, purified and identified. Prior to intraperitoneal sensitization and intranasal challenge with ovalbumin, mice were subcutaneously immunized three times with the vaccine, or the carrier or saline as controls. Serum antibodies, inflammatory cells in bronchoalveolar lavage fluids (BALF), lung histology, and responsiveness to inhaled methacholine were analyzed.

RESULTS

The vaccine presented as virus-like particles and reacted to polyclonal anti-IL-4 in Western blotting. Vaccinated mice produced high titers of IgG to IL-4. Serum ovalbumin-specific IgE, eosinophil accumulation in BALF, goblet cell hyperplasia, tissue inflammation and methacoline-induced respiratory responses were markedly suppressed in vaccinated mice with statistical significance, as compared with those in the control groups.

CONCLUSIONS

Administration of this novel IL-4 vaccine led to an overall decrease in the development of airway allergic inflammatory responses. The results indicate that cytokine peptide-based vaccines hold potential for treatment of asthma and, by extension, other diseases where over-expressed cytokines play a pivotal role in pathogenesis.

GABAA receptor alpha 4 subunits mediate extrasynaptic inhibition in thalamus and dentate gyrus and the action of gaboxadol

The neurotransmitter GABA mediates the majority of rapid inhibition in the CNS. Inhibition can occur via the conventional mechanism, the transient activation of subsynaptic GABAA receptors (GABAA-Rs), or via continuous activation of high-affinity receptors by low concentrations of ambient GABA, leading to "tonic" inhibition that can control levels of excitability and network activity. The GABAA-R alpha4 subunit is expressed at high levels in the dentate gyrus and thalamus and is suspected to contribute to extrasynaptic GABAA-R-mediated tonic inhibition. Mice were engineered to lack the alpha4 subunit by targeted disruption of the Gabra4 gene. alpha4 Subunit knockout mice are viable, breed normally, and are superficially indistinguishable from WT mice. In electrophysiological recordings, these mice show a lack of tonic inhibition in dentate granule cells and thalamic relay neurons. Behaviorally, knockout mice are insensitive to the ataxic, sedative, and analgesic effects of the novel hypnotic drug, gaboxadol. These data demonstrate that tonic inhibition in dentate granule cells and thalamic relay neurons is mediated by extrasynaptic GABAA-Rs containing the alpha4 subunit and that gaboxadol achieves its effects via the activation of this GABAA-R subtype.

Management of cardiovascular diseases with micro systems and nanotechnology

Cardiovascular diseases are the leading cause of death and morbidity in industrialized nations and are becoming an urgent health problem for all nations due to the unstoppable trend of an ageing and obese population. Due to the rapid development of micro total analysis systems (microTAS) and nanotechnology in recent years, they will play an important role in the diagnosis, management, and therapy of cardiovascular diseases. It is envisaged that the micro and nanotechnologies developed for treating other diseases shall be explored for cardiovascular applications to reduce the research effort required for commercializing the devices and drugs to meet the increasing demand of the cardiovascular patients.

A new recombinant mosquito salivary allergen, rAed a 2: allergenicity, clinical relevance, and cross-reactivity

BACKGROUND

Mosquito salivary proteins cause allergic reactions in humans. The allergenicity, clinical relevance, and species cross-reactivity of a new 37-kDa recombinant mosquito (Aedes aegypti) salivary allergen, rAed a 2, were evaluated.

METHODS

rAed a 2 was expressed using a baculovirus/insect cell system and purified. Its allergenicity was examined using an enzyme-linked immunosorbent assay (ELISA), ELISA inhibition tests, immunoblots, and skin tests. Epicutaneous tests with the allergen, mosquito whole body extracts, and mosquito bite tests were performed on 48 volunteers. Serum rAed a 2-specific immunoglobulin E (IgE) was measured in individuals with positive mosquito saliva-specific IgE and negative controls.

RESULTS

Both immunoblots and ELISAs demonstrated that rAed a 2 bound to the IgE of mosquito-allergic individuals. The binding could be inhibited by the addition of a natural mosquito preparation. Furthermore, rAed a 2 induced immediate and delayed skin reactions. Ten per cent of 31 participants with a positive mosquito bite test had positive skin reactions to rAed a 2, compared with 32% for mosquito whole body extract. None of the participants with a negative bite test showed positive reactions to either of the two extracts. Forty-three per cent of individuals with positive saliva-IgE had positive rAed a 2-IgE. rAed a 2 was a species-shared allergen, being present in the saliva of the 11 species studied.

CONCLUSIONS

rAed a 2 has identical antigenicity and biologic activity to its native form. It can be used in the diagnosis of mosquito allergy, and is an important species-shared antigen.

Dynamic Airflow Limitation after Topical Anaesthesia of the Upper Airway

This prospective before-and-after observational study investigated the effect of upper airway anaesthesia on dynamic airflow. Six consenting ASA 1 adults, all authors of this study, underwent a series of Spirometric measurements before and after topical anaesthesia of the upper airway using lignocaine. Peak inspiratory flow rate, forced inspiratory flow between 25% and 75% of the maximum inhaled volume, forced expiratory volume at 1 second, and forced vital capacity in the supine and sitting positions were measured. The measured inspiratory parameters were significantly reduced after lignocaine topical anaesthesia of the upper airway. Expiratory flow parameters were not affected. We conclude that topical anaesthesia of the upper airway leads to dynamic inspiratory airflow limitation.

Dynamics of a projectile penetrating in granular systems

The impact of a sphere with velocity u0 on a fine, loose granular system under the acceleration due to gravity has been studied by fast video photography. The behavior of the granular bed is found to be similar to a fluid during initial impact, followed by a cavity drag during projectile penetration. From the trajectory of the projectile it is found that the drag on the projectile can be well described by adding a bulk frictional force f to the hydrostatic force kappa(z) where kappa is a constant and z denotes the penetration depth. Both kappa and f are u0 dependent. This form of the drag force suggests that fluidlike viscous dissipations in the bed can be neglected in these three-dimensional (3D) experiments. However, due to the imposed boundary this hydrodynamic term of the drag force is found to be not negligible in quasi-2D granular beds.

A sensitive in situ ELISA for quantitative measurements of cytokines and antibodies secreted by culture lymphocytes

Cytokines are usually measured using ELISA and ELISPOT. We have developed an in situ ELISA by combining the advantages of the highly sensitive ELISPOT and the quantitative conventional ELISA techniques to measure cytokines and antibodies secreted by culture lymphocytes. In this assay, lymphocytes were cultured on ELISA plates pre-coated with either a special antigen or mAbs against IL-4, IFN-gamma. The caprtured lymphokines or immunoglobulins were subsequently measured by conventional ELISA procedures. As a comparison, a conventional ELISA was carried out in parallel. The in situ ELISA measured a 5-fold increase in antigen-stimulated IL-4 and IFN-gamma, compared to the conventional ELISA. It also rquired 10,000 times fewer lymphocytes to produce a detectable level of antigen-specific antibodies than the conventional ELISA. We conclude that the in situ ELISA is much more sensitive than a conventional ELISA and less costly and easier to perform than ELISPOT, providing a useful tool to quantitatively measure cell-secreted molecules.

Anaphylaxis from topical bovine thrombin (Thrombostat) during haemodialysis and evaluation of sensitization among a dialysis population

BACKGROUND

Topical bovine thrombin (TBT) is used as a topical haemostatic agent in haemodialysis (HD) units and for surgical procedures. It has caused allergic reactions during surgical procedures, but no previous cases have been reported with dialysis usage.

OBJECTIVE

A case is reported of anaphylaxis due to TBT in an HD patient. This led to a determination of whether HD patients exposed to TBT develop specific IgE and IgG antibodies to TBT and an assessment of the frequency of allergic symptoms in HD patients as compared with peritoneal dialysis (PD) patients.

METHODS

A cross-sectional study of 100 HD and 52 PD patients was performed using a questionnaire to determine allergic symptoms. An ELISA assay was developed to determine TBT-specific IgE and IgG serum antibodies among HD patients. HD patients without TBT exposure and age- and gender-matched blood donors served as controls.

RESULTS

Allergic symptoms temporally related to dialysis reported by a questionnaire were significantly more frequent for HD patients than for PD patients: rhinoconjuctivitis 11% vs. 2%, asthma symptoms 20% vs. 6%, urticaria 23% vs. 8% (P values <0.05). Positive TBT-specific IgE and IgG antibodies were more frequent among 65 exposed HD patients (28% for IgE and 26% for IgG) than for controls (4% and 9%), P<0.05.

CONCLUSIONS

Results indicate the potential for sensitization and clinical allergic responses to beef thrombin when used for haemostasis in HD and suggest that other haemostatic methods should be considered.

Electrochemistry and spectroscopy study on the interaction of microperoxidase-11 with lipid membrane

The interaction of microperoxidase-11 (MP11) with cationic lipid vesicles of didodecyldimethylammonium bromide (DDAB) induces an alpha-helical conformation from random coil conformations in solution and this change then makes heme macrocycle more distorted. DDAB-induced MP11 conformations were investigated by cyclic votammetry (CV), circular dichroism (CD) and UV-vis spectrometry. All results indicate that the binding of MP11 in solution to DDAB vesicles and the ordered structure formation are driven by mostly electrostatic interaction between negatively charged residues in the undecapeptide and positively charged lipid headgroups on the membrane surface. Upon binding to DDAB, its half-peak potential was also changed. The mechanism of the interaction between MP11 and DDAB was also discussed.