Specific Kinase Activity Research Articles

Abstract 3122: Her4 and Her2/neu tyrosine kinase domains dimerize and activate in a reconstituted in vitro system

Abstract Her4 (ErbB-4) and Her2/neu (ErbB-2) are receptor tyrosine kinases belonging to the Epidermal Growth Factor Receptor (EGFR) family. Crystal structures of EGFR and Her4 kinase domains have demonstrated kinase dimerization and activation through an allosteric mechanism. The kinase domains form an asymmetric dimer, where the C-lobe surface of one monomer contacts the N-lobe of the other monomer. In vitro studies of EGFR tyrosine kinase dimerization and activation were previously reported using a nickel-chelating lipid - liposome system, and we now demonstrate this system can be broadly applied to all other members of the EGFR family. Polyhistidine tagged-Her4, Her2/neu, and Her3 kinase domains are bound to these nickel-chelating lipid containing liposomes and are brought to a high local concentration, mimicking what happens to the full-length receptors in vivo following ligand binding. Addition of Nickel-liposomes to Her4 kinase domain results in a 40-fold activation in kinase specific activity and a marked enhancement in C-terminal tail autophosphorylation. Activation of Her4 shows a sigmoidal dependence on kinase concentration, consistent with a cooperative process that requires kinase dimerization. Her2/neu kinase activity is also activated by Nickel-liposomes, and further increases in Her2/neu activity are achieved by heterodimerization with either Her3 or Her4. The ability of Her3 and Her4 to heterodimerize and activate other family members is studied in vitro. Her3 kinase domain readily activates Her2/neu but is a poor activator of Her4, which differs from the prediction made by the asymmetric dimer model, and suggests that the mode of dimerization of Her3 needs to be further studied. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 3122.

Peptide reporters of kinase activity in whole cell lysates

Kinase assays are used to screen for small-molecule inhibitors that may show promise as targeted pharmaceutical therapies. Using cell lysates instead of purified kinases provides a more accurate estimate of inhibitor sensitivity and selectivity in a biological setting. This review summarizes the range of homogeneous (solution-phase) and heterogeneous (solid-supported) formats available for using peptide substrates to monitor kinase activities in cell lysates. With a focus on heterogeneous kinase assays, the peptide substrate Abltide is used as a model to optimize presentation geometries and the modular arrangement of short sequences for kinase recognition. We present results from peptides immobilized on two- and three-dimensional surfaces such as hydrogels on 96-well plates and glass slides, and fluorescent Luminex beads. We discuss methods to increase assay sensitivity using chemifluorescent ELISAs, antibody-based recognition, and label-free mass spectrometry. Monitoring the activity of specific kinases in cell lysates presents challenges that can be overcome by manipulating peptide substrates to optimize assay conditions. In particular, signal-to-background ratios were improved by (1) adding long branched hydrophilic linkers between the substrate and the surface, (2) changing the orientation of peptides relative to the surface, and (3) including peptide ligands in cis or in trans to recruit kinases to the surface. By improving the accessibility of immobilized peptide substrates to kinases in solution, the apparent rate of phosphorylation increased and assays were more sensitive to changes in endogenous kinase activities. These strategies can be generalized to improve the reactivity of most peptide substrates used in heterogeneous kinase assays with cell lysates.

NIK and IKKβ interdependence in NF-κB signalling—Flux analysis of regulation through metabolites

Activation of the transcription factor NF-κB is central to control of immune and inflammatory responses. Cytokine induced activation through the classical or canonical pathway relies on degradation of the inhibitor, IκBα and regulation by the IKKβ kinase. In addition, the NF-κB is activated through the NF-κB-inducing kinase, NIK. Analysis of the IKK/NIK inter-relationship and its impact on NF-κB control, were analysed by mathematical modelling, using matrix formalism and stoichiometrically balanced reactions. The analysis considered a range of bio-reactions and core metabolites and their role in relation to kinase activation and in control of specific steps of the NF-κB pathway. The model predicts a growth-rate and time-dependent transfer of the primary kinase activity from IKKβ to NIK. In addition, it suggests that NIK/IKKβ interdependence is controlled by intermediates of phosphoribosylpyrophosphate (PRPP) within the glycolysis pathway, and thus, identifies a link between specific metabolic events and kinase activation in inflammatory signal transduction. Subsequent in vitro experiments, carried out to validate the impact of IKK/NIK interdependence, confirmed signal amplification at the level of the NF-κB/IκBα complex control in the presence of both kinases. Further, they demonstrate that the induced potentiation is due to synergistic enhancement of relA-dependent activation.

Cyclin D1 Degradation Is Sufficient to Induce G1 Cell Cycle Arrest despite Constitutive Expression of Cyclin E2 in Ovarian Cancer Cells

D- and E-type cyclins mediate G(1)-S phase cell cycle progression through activation of specific cyclin-dependent kinases (cdk) that phosphorylate the retinoblastoma protein (pRb), thereby alleviating repression of E2F-DP transactivation of S-phase genes. Cyclin D1 is often overexpressed in a variety of cancers and is associated with tumorigenesis and metastasis. Loss of cyclin D can cause G(1) arrest in some cells, but in other cellular contexts, the downstream cyclin E protein can substitute for cyclin D and facilitate G(1)-S progression. The objective of this study was to determine if a flexible heteroarotinoid anticancer compound, SHetA2, regulates cell cycle proteins and cell cycle progression in ovarian cancer cells. SHetA2 induced cyclin D1 phosphorylation, ubiquitination, and proteasomal degradation, causing G(1) arrest in ovarian cancer cells despite continued cyclin E2 expression and independently of p53 and glycogen synthase kinase-3beta. Cyclin D1 loss inhibited pRb S780 phosphorylation by cyclin D1-cdk4/6 and released p21 from cyclin D1-cdk4/6-p21 protein complexes to form cyclin E2-cdk2-p21 complexes, which repressed phosphorylation of pRb S612 by cyclin E2-cdk2 and ultimately E2F-DP transcriptional activity. G(1) arrest was prevented by overexpression or preventing degradation of cyclin D1 but not by restoration of pRb S612 phosphorylation through p21 knockdown. In conclusion, we show that loss of cyclin D1 in ovarian cancer cells treated with SHetA2 is sufficient to induce G(1) cell cycle arrest and this strategy is not impeded by the presence of cyclin E2. Therefore, cyclin D1 is a sufficient therapeutic target in ovarian cancer cells.

Paclitaxel alters the expression and specific activity of deoxycytidine kinase and cytidine deaminase in non-small cell lung cancer cell lines

BackgroundWe observed that paclitaxel altered the pharmacokinetic properties of gemcitabine in patients with non-small cell lung cancer (NSCLC) and limited the accumulation of gemcitabine and its metabolites in various primary and immortalized human cells. Therefore, we classified the drug-drug interaction and the effects of paclitaxel on deoxycytidine kinase (dCK) and cytidine deaminase (CDA) in three NSCLC cell lines. These enzymes are responsible for the metabolism of gemcitabine to its deaminated metabolite dFdU (80% of the parent drug) and the phosphorylated metabolites dFdCMP, dFdCDP and dFdCTP. These metabolites appear to relate to sensitivity and tolerability of gemcitabine based on previous animal and laboratory studies.MethodsThree immortalized human cells representative of the most common histological subtypes identified in patients with advanced NSCLC were exposed to the individual drugs or combinations to complete a multiple drug effect analysis. These same cell lines were exposed to vehicle-control or paclitaxel and the mRNA levels, protein expression and specific activity of dCK and CDA were compared. Comparisons were made using a two-tailed paired t-test or analysis of variance with a P value of < 0.05 considered significant.ResultsThe multiple drug effect analysis indicated synergy for H460, H520 and H838 cells independent of sequence. As anticipated, paclitaxel-gemcitabine increased the number of G2/M cells, whereas gemcitabine-paclitaxel increased the number of G0/G1 or S cells. Paclitaxel significantly decreased dCK and CDA mRNA levels in H460 and H520 cells (40% to 60%, P < 0.05) and lowered dCK protein (24% to 56%, P < 0.05) without affecting CDA protein. However, paclitaxel increased both dCK (10% to 50%) and CDA (75% to 153%) activity (P < 0.05). Paclitaxel caused substantial declines in the accumulation of the deaminated and phosphorylated metabolites in H520 cells (P < 0.05); the metabolites were not measurable in the remaining two cell lines. The ratio of dCK to CDA mRNA levels corresponded to the combination index (CI) estimated for sequential paclitaxel-gemcitabine.ConclusionIn summary, paclitaxel altered the mRNA levels and specific activity of dCK and CDA and these effects could be dependent on histological subtype. More cell and animal studies are needed to further characterize the relationship between mRNA levels and the overall drug-drug interaction and the potential to use histological subtype as a predictive factor in the selection of an appropriate anticancer drug regimen.

Modeling ATM mutant proteins from missense changes confirms retained kinase activity

Ataxia-telangiectasia mutated (ATM) is the gene mutated in the cancer-predisposing disorder ataxia-telangiectasia (A-T). We modeled ATM sequence variants identified in UK A-T patients to determine the stability and kinase activity of the resulting proteins as well as the distribution of these mutations across the coding region. Of 20 missense changes modeled, 10 proteins showed ATM kinase activity and 10 showed none. In the majority of cases the mutant ATM protein was unstable, although this was variable. Reduction in ATM kinase activity can result either from the presence of low levels of unstable mutant protein with relatively normal specific kinase activity or from stable mutant protein with deficient ATM kinase activation. Indeed, ATM mutant proteins without kinase activity toward downstream targets were still able to autophosphorylate on serine 1981, although in a much less efficient manner, suggesting that this was not sufficient for ATM activation. In terms of function, green fluorescent protein (GFP)-tagged kinase inactive ATM proteins could form ionizing radiation (IR)-induced foci (IRIF), at least temporarily, which colocalized with the DNA double-strand break (DSB) marker gammaH2AX. Consistent with this, both kinase active and inactive mutant ATM proteins were able to interfere with phosphorylation of targets by endogenous ATM. Since the majority of missense mutations occurred C-terminal to aa1966, including all 10 mutations with absence of kinase activity, the implication was that mutations N-terminal to this, with exceptions, are less likely to result in loss of kinase activity and therefore, are less likely to be identified in A-T patients.

QSAR analysis of pyrazolidine-3,5-diones derivatives as Dyrk1A inhibitors

Individuals with Down syndrome (DS) suffer from mental retardation. Overexpression and the resulting increased specific activity of Dyrk1A kinase located on chromosome 21 cause a learning and memory deficit in Dyrk1A transgenic mice. To search for therapeutic agents with Dyrk1A inhibition activity, previously we obtained HCD160 as a new hit compound for Dyrk1A inhibition. In the present study, we synthesized 34 HCD160 derivatives to investigate the quantitative structure–activity relationship (QSAR). This analysis could provide important information for novel drug discovery for treatment of DS related learning and memory deficits.

Extremely low frequency electromagnetic fields activate the ERK cascade, increase hsp70 protein levels and promote regeneration in Planaria

Purpose: To use regenerating Planaria Dugesia dorotocethala as a model to determine whether an intermittent modulated extremely low frequency electro-magnetic field (ELF-EMF) produces elevated levels of the heat shock protein hsp70 and stimulates intracellular pathways known to be involved in injury and repair. We focused on serum response element (SRE) binding through the extra-cellular signal-regulated kinase (ERK) cascade.Materials and methods: Planaria were transected equidistant between the tip of the head and the tip of the tail. Individual head and tail portions from the same worm were exposed to a 60 Hertz 80 milliGauss ELF-EMF for 1 h twice daily for 15 days post-transection under carefully controlled exposure conditions. The regenerating heads and tails were photographed and the lengths measured at three-day intervals. In other experiments, the timing of the appearance of pigmented eyes was monitored in the tail portion at 12-h intervals following transection in both ELF-EMF exposed and sham control. In some experiments protein lysates were analysed for hsp70 levels, doubly phosphorylated (pp)-ERK, Elk-1 kinase activity and serum response factor (SRF)-SRE binding.Results: ELF-EMF exposure during the initial 3-days post-surgery caused a significant increase in regeneration for both heads and tails, but especially tails. The first appearance of eyes occurred at day seven post-transection in tail portions exposed to ELF-EMF. In the sham control tail samples the initial appearance of eyes occurred 48 h later. Concurrently, ELF-EMF-exposed heads and tails exhibited an elevation in the level of hsp70 protein, an activation of an ERK cascade, and an increase in SRF-SRE binding.Conclusion: Exposures to a modulated sinusoidal ELF-EMF were delivered by a Helmholtz configuration at a frequency of 60 Hz and 80 mG twice a day for one hour. This is accompanied by an increase in hsp70 protein levels, activation of specific kinases and upregulation of transcription factors that are generally associated with repair processes.

The Response of Creatine Kinase Specific Activity in Rat Pituitary to Estrogenic Compounds and Vitamin D Less-Calcemic Analogs

We examined the response of rat female pituitary at different metabolic stages to treatments with estrogenic compounds and vitamin D analogs. Immature or ovariectomized (Ovx) female rats responded by increased creatine kinase specific activity (CK) to estradiol-17β (E2), genistein (G), daidzein (D), biochainin A (BA), quecertin (Qu), carboxy- G (cG), carboxy- BA (cBA), and raloxifene (Ral). The response was inhibited when Ral was injected together with the estrogens. CK was increased when hormones were injected daily into Ovx rats for 4 different time periods. Pretreatment with the less-calcemic vitamin D analogs JK 1624 F2-2 (JKF) or QW 1624 F2-2 (QW) followed by estrogenic injection resulted in increased response and sensitivity to E2 and loss of inhibition of E2 by Ral. CK was also increased by feeding with E2 or licorice or its components dose- and time- dependent in immature or Ovxrats. Diabetic female rats did not respond to increased doses of E2. In conclusion, rat female pituitary is estrogens-responsive organ, suggesting to considerits response for HRT in postmenopausal women for both beneficial and hazardous aspects.

Targeting the Bcl-2 Family of Proteins in Hodgkin Lymphoma: In Vitro Cytotoxicity, Target Modulation and Drug Combination Studies of the BH3 Mimetic ABT-737

Introduction: Currently, patients with refractory Hodgkin lymphoma (HL) or those who relapse multiple times have an extremely poor prognosis. Even patients who do not relapse often experience late toxicities, including secondary cancer, heart failure, pulmonary dysfunction, and infertility. Therefore, new agents and novel therapeutic approaches are urgently needed. Anti-apoptotic proteins such as Bcl-2 and Bcl-xl have been found to be associated with the growth and survival of Hodgkin Reed–Sternberg cells and thus carry the potential to be effective targets for therapeutics. In this study we report the in vitro cytotoxicity, biological correlative findings and drug combination analysis of the novel BH3 mimetic ABT-737 [Abbott laboratories (Abbott Park, IL)] against HL cells.Materials and Methods: HL cell lines (KMH2 and HDLM2) were cultured in the presence of increasing concentrations of ABT-737 or its enantiomer control. Normal bone marrow stromal cells were used as controls for non-specific cytotoxicity. Cell growth inhibition was measured by Alamar blue assay and the induction of apoptosis was demonstrated by an annexin specific staining technique. Time and drug concentration dependent changes in proteins involved in cell survival and apoptosis were investigated by Western blot analysis. The ability of ABT-737 to influence the anti-lymphoma activity of a panel of twenty distinct chemotherapeutic agents was evaluated by drug combination and cell growth inhibition studies. Combination indices (CI) were calculated to identify therapeutic enhancement of different agents in the presence of Bcl-2 inhibition by ABT-737.Results: ABT-737 showed significant dose-dependent cytotoxicity and apoptotic activity against HL cells with an approximate IC50 of 1mM with maximum cell death occurring at about 5mM. At the molecular level, increased levels of cleaved caspase3 and PARP, as well as annexin positivity, were noticeable within three hours of treatment with the agent. Drug combination studies have shown the ability of Bcl-2 inhibition to synergize with novel therapeutic agents that target histone deacetylase function (Apicidin, CI 0.35), Hsp90 stability (17-AAG, CI 0.3) and the activity of specific receptor tyrosine kinases (Sorafenib, CI 0.7 and Sunitinib CI 0.3 for HDLM2 and CI 0.9 for KMH2). Among conventional anti-neoplastic agents, ABT-737 showed significant synergistic activity with irinotecan and oxaliplatin (CI 0.6). Importantly, treatment with ABT-737 decreased the expression of the critical HL cell growth promoter, NF- B as determined by band densities on Western blot analysis: a two fold decrease in KMH2 and a five fold decrease in HDLM2 cells. Specific target modulation was demonstrated by changes in key apoptosis and cell survival regulators such as Bcl-XS/L, Bcl-X, p53 and survivin by two to 10 fold decreases in Western blots.Discussion: Data presented in this study support the hypothesis that Bcl-2 family of proteins can be an effective target for therapeutics in HL. We have shown that the BH3 mimetic ABT-737 induces apoptosis in these cells, characterized by the modulation of key components of cell growth and survival pathways. In addition, we have identified distinct classes of anti-lymphoma and anti-neoplastic agents whose activities are enhanced by concurrent inhibition of Bcl-2. These findings provide the rationale for further evaluation of ABT-737 and the subsequent clinical development of a targeted anti-Bcl-2 therapy for refractory Hodgkin lymphoma.

Stretch‐induced activation of ERK in myocytes is p38 and calcineurin‐dependent

Activation of specific mitogen-activated protein kinases (MAPKs) has been suggested to be involved in phenotype modulation of cells subjected to mechanical strain, which may be common to different mechano-sensitive cell types. We have submitted C2C12 myocytes to a static stretch and examined its effect upon the activation of ERK. Stretch induced a rapid but transient activation of ERK. This activation was however prevented when cells were pre-treated with inhibitors of p38 and calcineurin. The dependence of strain-induced ERK activation upon p38 suggests a cross-talk between these two pathways when mediating a response to a mechanical stimulus in this cell type. This suggests that cross relationships between these MAP kinases may be of crucial importance for myocyte phenotype modulation and differentiation in response to a mechanical stimulus.

Prolonged treatment of porcine pulmonary artery with nitric oxide decreases cGMP sensitivity and cGMP-dependent protein kinase specific activity

A cultured porcine pulmonary artery (PA) model was used to examine the effects of prolonged nitric oxide (NO) treatment on the response to acutely applied NO, cGMP analog, or atrial natriuretic peptide (ANP). Twenty-four-hour treatment with the NO donor (Z)-1-[N-(2-aminoethyl)-N-(2-ammonioethyl)amino]diazen-1-ium-1,2-diolate (DETA-NO) resulted in >10-fold decrease in the response to acutely applied DETA-NO. In parallel with this, the relaxant response to acutely applied cGMP analog, beta-phenyl-1,N(2)-etheno-8-bromoguanosine-3',5'-cyclic monophosphorothioate, Sp isomer (Sp-8-Br-PET-cGMPS), and ANP decreased. The reduction in ANP responsiveness in PA was not associated with a reduction in cGMP levels evoked by 10(-6) M ANP. Twenty-four hours in culture and treatment with DETA-NO decreased total cGMP-dependent protein kinase (cGKI) mRNA level compared with that in freshly prepared PA (1.05 +/- 0.12, 0.42 +/- 0.08, and 0.11 +/- 0.01 amol/mug, respectively). Total cGKI protein levels were decreased to a lesser extent by 24 h in culture and further decreased by 24-h DETA-NO treatment compared with that in freshly prepared PA (361 +/- 33, 272 +/- 20, and 238 +/- 25 ng/mg total protein, respectively). Maximal cGMP-stimulated phosphotransferase activity was reduced in 24-h cultured and DETA-NO-treated PA (986 +/- 84, 815 +/- 81, and 549 +/- 78 pmol P(i).min(-1).mg soluble protein(-1)), but the cGMP concentration resulting in 50% of maximal phosphotransferase activity was not. cGKI specific activity (maximal cGMP-activated phosphotransferase activity/ng cGKI) was significantly reduced in PA treated with DETA-NO for 24 h compared with freshly prepared and 24-h cultured PA (1.95 +/- 0.22, 2.64 +/- 0.25, and 2.85 +/- 0.28 pmol P(i).min(-1).ng cGKI(-1), respectively). We conclude that prolonged NO treatment induces decreased acute NO responsiveness in PA in part by decreasing cGMP sensitivity. It does so by decreasing both cGKI expression and cGKI specific activity.

Incidence of apoptosis in parthenogenetic porcine embryos generated by using protein kinase or protein synthesis inhibitors

In mammals, embryonic development can be artificially initiated by activating the oocyte using a number of methods. In the present research, we investigated whether butyrolactone I and cycloheximide, two chemicals frequently used in combined oocyte activation protocols, have any detrimental effect on programmed cell death in the developing porcine embryo. Parthenogenetic porcine blastocysts were generated by the following methods: (1) electroporation followed by blocking the activity of specific protein kinases with butyrolactone I; (2) electroporation followed by inhibition of protein synthesis using cycloheximide; and (3) electroporation only (control). The viability of the embryos was evaluated by monitoring the frequency of cells with early and late signs of programmed cell death. There was no difference between the embryos in terms of blastocyst formation (ranging from 27.5 ± 3.8 and 33.3 ± 3.5%) and total nuclear number (ranging from 23.5 ± 1.1 and 31.8 ± 4.4). In addition, the occurrence of apoptosis was also similar in the three experimental groups. The proportion of cells with active caspase-9 (a sign of early apoptosis) in the blastocysts produced by the different activation methods was between 19.4 ± 1.9 and 23.0 ± 2.4%. The annexin V assay revealed that phosphatidylserine flip (another early apoptotic event) took place in 24.4 ± 2.1 to 32.3 ± 2.4% of the blastomeres. Finally DNA fragmentation, a sign of late stage apoptosis determined by the TUNEL assay, occurred in 8.5 ± 2.4 to 10.1 ± 3.0% of the cells. The results indicate that temporary inhibition of specific protein kinases or protein synthesis does not increase the onset of apoptosis in parthenogenetic porcine blastocysts.

Daidzein but not other phytoestrogens preserves bone architecture in ovariectomized female rats in vivo

Ovariectomy of immature female rats, results in significant decrease of trabecular bone volume and in cortical bone thickness. Previously, we found that estradiol-17beta (E(2)) restored bone structure of ovariectomized (Ovx) female rats to values obtained in intact sham-operated female rats. E(2) also selectively stimulated creatine kinase (CK) specific activity a hormonal-genomic activity marker. In the present study, we compared the effects of E(2) and the phytoestrogens: daidzein (D), biochainin A (BA), genistein (G), carboxy-derivative of BA (cBA), and the SERM raloxifene (Ral) in Ovx, on both histological changes of bones and CK, when administered in multiple daily injections for 2.5 months. Bone from Ovx rats, showed significant disrupted architecture of the growth plate, with fewer proliferative cells and less chondroblasts. The metaphysis underneath the growth plate, contained less trabeculae but a significant increased number of adipocytes in the bone marrow. D like E(2) and Ral but not G, BA, or cBA, restored the morphology of the tibiae, similar to that of control sham-operated animals; the bony trabeculeae observed in the primary spongiosa was thicker, with almost no adipocytes in bone marrow. Ovariectomy resulted also in reduced CK, which in both epiphysis and diaphysis was stimulated by all estrogenic compounds tested. In summary, only D stimulated skeletal tissues growth and differentiation as effectively as E(2) or Ral, suggesting that under our experimental conditions, D is more effective in reversing menopausal changes than any of the other isolated phytoestrogens which cannot be considered as one entity.

A Phase I Study of INNO-406 in Patients with Advanced Philadelphia (Ph+) Chromosome-Positive Leukemias Who Are Resistant or Intolerant to Imatinib and Second Generation Tyrosine Kinase Inhibitors.

Background: INNO-406 is an orally available, dual Abl/Lyn kinase inhibitor that is up to 55-times more potent than imatinib in Bcr-Abl expressing cell lines. Numerous Bcr-Abl mutant proteins are sensitive to INNO-406 in vitro, including the F317L mutant. Unlike other second generation tyrosine kinase inhibitors (TKIs), INNO-406 demonstrates specific Lyn kinase activity with no or limited activity against other Src-family member kinases.Methods: In this phase I dose finding study, patients (pts) with imatinib-resistant or -intolerant Philadelphia (Ph+) chromosome-positive leukemias were eligible for treatment with INNO-406 orally at doses ranging from 30 mg once daily (qd) through 480 mg twice daily (bid).Results: INNO-406 was administered to 41 pts (23M, 18F); median age 61 yrs (range, 20–76). Median duration of CML was 6 yrs (range, 0.1–23); median time on imatinib was 0.8 yrs (range, 0.1–6.5). Pts had CML in chronic phase (CP, n=21), accelerated phase (AP, n=7), or blast phase (BP, n=6), or Ph+ ALL (n=7). Previous treatment included nilotinib (n=9), dasatinib (n=13), and dasatinib/nilotinib (n=10). Pts have been treated with INNO-406 for a median of 42 days (range, 7–240+). Common mutations on study entry included Y253H (n=4), F311L (n=3), F317L (n=2), and T315I (n=2). Currently, 14 pts remain on study; 22 pts discontinued due to disease progression, 4 pts discontinued to pursue other treatment options, and 1 pt discontinued due to toxicity. Hematologic and cytogenetic responses have been reported. 2 of 7 CP pts who had failed only imatinib demonstrated a complete cytogenetic response, including 1 major molecular response. An additional pt had a minor cytogenetic response after 4 weeks of therapy before going off study to pursue an alternate treatment option. Among pts in CP who had failed more than one TKI, a complete cytogenetic response was reported in 1 pt who was intolerant to both imatinib (lung/skin toxicity) and dasatinib (pleural effusion). All 7 AP pts on study had failed multiple TKIs. In this population, 2 pts experienced complete hematologic responses. Additionally, in 1 pt, a reversion of the Y253H mutation was demonstrated, and 1 pt has experienced a disappearance of the F317L mutation. Related adverse events include reversible grade 2/3 elevation in the activity of transaminases. A DLT was reported in 1 pt in the 480 mg bid cohort (intrahepatic cholestasis and renal failure secondary to tumor lysis syndrome).Conclusions: INNO-406 is well tolerated in pts with clinical activity demonstrated across a range of dosing. Responses occur even in the setting of a heavily pretreated population thus making INNO-406 a viable option for CML therapy. The recommended phase II dose is anticipated to be 240 mg bid. Pivotal phase II studies are planned for late 2007.

Soluble Aβ Inhibits Specific Signal Transduction Cascades Common to the Insulin Receptor Pathway

Numerous studies have now shown that the amyloid beta-protein (Abeta), the principal component of cerebral plaques in Alzheimer disease, rapidly and potently inhibits certain forms of synaptic plasticity. The amyloid (or Abeta) hypothesis proposes that the continuous disruption of normal synaptic physiology by Abeta contributes to the development of Alzheimer disease. However, there is little consensus about how Abeta mediates this inhibition at the molecular level. Using mouse primary hippocampal neurons, we observed that a brief treatment with cell-derived, soluble, human Abeta disrupted the activation of three kinases (Erk/MAPK, CaMKII, and the phosphatidylinositol 3-kinase-activated protein Akt/protein kinase B) that are required for long term potentiation, whereas two other kinases (protein kinase A and protein kinase C) were stimulated normally. An antagonist of the insulin receptor family of tyrosine kinases was found to mimic the pattern of Abeta-mediated kinase inhibition. We then found that soluble Abeta binds to the insulin receptor and interferes with its insulin-induced autophosphorylation. Taken together, these data demonstrate that physiologically relevant levels of naturally secreted Abeta interfere with insulin receptor function in hippocampal neurons and prevent the rapid activation of specific kinases required for long term potentiation.

Sarcoplasmic reticulum-mitochondrial interaction in the mechanism of acute reperfusion injury

Currently, restoring blood flow in an acutely occluded vessel represents the most effective, long-term clinical therapy for acute myocardial infarction. Experimental research over the past years has demonstrated that the first minutes of reperfusion represent a window of opportunity for additional therapy that is yet unused in the clinical setting. Experimentally, it has been shown that a considerable part of myocardial injury developing after an episode of prolonged ischaemia and subsequent reperfusion is due to causes emerging during the period of reperfusion.1–6 This type of injury has been termed ‘reperfusion injury’. For a long time it had been difficult to prove the existence of this type of injury; this could only be done by identifying interventions applied just at the time of reperfusion that would reduce the otherwise resulting myocardial injury. Early studies in this area had shown that interventions during reperfusion aimed at controlling cytosolic [Ca2+] or the activation of the contractile machinery in cardiomyocytes could reduce cardiac cell necrosis.7–10 More recently, a protective protocol called ‘postconditioning’11 has been discovered that can be used in the clinical setting. In this protocol, very brief, repetitive bouts of ischaemia are deliberately applied during the first minutes of reperfusion. In ground-breaking work, Ovize and co-workers12,13 showed that postconditiong can reduce the signs of tissue injury, such as the release of myocardial enzymes, in patients receiving acute coronary revascularisation. In a rapidly growing number of manuscripts, details of the protective signalling of postconditioning and pharmacological interventions designed to exploit its protective potential have been identified. It has become apparent that activation of specific protein kinases can provide and mediate cardiac protection during the reperfusion period. These have been termed ‘reperfusion injury salvage kinases’ (RISK).14–16 …

Identification of proteins directly phosphorylated by UL13 protein kinase from herpes simplex virus 1

Herpes simplex virus 1 (HSV-1) UL13 is a viral protein kinase that regulates optimal viral replication in cell cultures. Identification of substrates of protein kinases is a crucial step to elucidate the mechanism by which they function. Using our developed system to analyze the specific protein kinase activity of UL13, we have shown that UL13 protein kinase directly phosphorylates the viral proteins ICP22 and UL49 previously reported to be putative substrates. We also identified UL41 as a previously unreported and novel substrate of UL13. These data will serve as a basis to clarify the mechanism by which UL13 influences viral replication.

Inhibition of colon tumor metastasis in an orthotopic nude mouse model with the dual selective Src/Abl kinase inhibitor, AZD0530

14032 Background: Colorectal cancer is the leading cause of cancer deaths in the USA, largely due to metastatic disease in the liver. The specific activity of the non-receptor protein tyrosine kinase, Src, is increased during colon tumor progression and contributes to metastasis; thus, Src inhibitors may have efficacy in the treatment of advanced-stage colon cancer. AZD0530 is a potent, orally available Src/Abl kinase inhibitor currently in clinical trials. Methods: We examined the effects of AZD0530 alone and in combination with oxaliplatin on two colon tumor cell lines, KM12L4 and LS174T in vitro and in orthotopic nude mouse models. AZD0530 inhibits in vitro proliferation and cellular migration of KM12L4 and LS174T, and decreases phosphorylation of the Src substrates FAK and paxillin in a dose- dependent manner. To examine the ability of AZD0530 to affect colon cancer growth and metastasis in a nude mouse model, we inoculated 1x106 cells into the cecum of nude mice. After 2 weeks, mice were treated with vehicle (n=12), AZD0530 alone (n=13; 25mg/kg/day by oral gavage), oxaliplatin alone (n=13; 5mg/kg/day twice weekly), or AZD0530 and oxaliplatin (n=13). Mice were sacrificed after 4 weeks of treatment. Results: Tumor incidence in all groups of mice was greater than 80%. Mice treated with AZD0530 had an average cecal tumor weight of 0.26 g compared with 0.32 g for control (P=0.24). In contrast, the incidence of liver metastases was reduced by 50% in mice treated with AZD0530 alone or oxaliplatin alone, and no mice developed pathologically evident liver metastases when the combination of inhibitors was used. Furthermore, in mice that developed liver metastases, AZD0530 decreased the size of these metastases 9-fold compared with control. Immunohistochemical analysis of primary cecal tumors demonstrated a decrease in phosphorylated Src (Y418) and FAK (Y861) in AZD0530-treated mice compared with control. Conclusions: These results support further investigation of AZD0530, both alone and in combination, as a new therapeutic strategy for the treatment of advanced colon cancer. No significant financial relationships to disclose.

A phase I study of INNO-406, a dual inhibitor of Abl and Lyn kinases, in adult patients with Philadelphia chromosome positive (Ph+) chronic myelogenous leukemia (CML) or acute lymphocytic leukemia (ALL) relapsed, refractory, or intolerant of imatinib

7046 Background: INNO-406 is an orally available, dual Abl/Lyn kinase inhibitor that is up to 55-times more potent than imatinib in Bcr-Abl cell lines. Numerous Bcr-Abl mutant proteins (not T315I) are sensitive to INNO-406 in vitro. INNO-406 demonstrates specific Src kinase activity against Lyn kinase. Methods: In this phase I study, patients with imatinib-resistant or intolerant Philadelphia (Ph+) chromosome- positive leukemias were eligible for treatment with INNO-406 once a day, orally. Results: 14 pts [median age: 58 yrs (range 18–74); 7 male, 7 female; median CML duration: 53 mo. (range 14–266); and median time on imatinib 45 months (range 12–129); chronic phase CML (8 pts), accelerated phase CML (2 pts), blast phase CML (1 pt), Ph+ ALL (3 pts); previous treatment with nilotinib (5 pts), dasatinib (6 pts)] have been enrolled in the following dose cohorts (mg/day): 30 (3 pts), 60 (3), 120 (6) and 240 mg (2), and have been on treatment between 7 and 123 days. 3 pts remain on study; 10 pts discontinued with disease progression [data unmonitored]. 6 patients who have completed &gt;1 month of treatment, 3 have evidence of clinical response. Patient 5, a chronic phase CML treated with imatinib for 69 mo. before developing resistant disease with an Y253H mutation, had a minimal cytogenetic response after 1 month of INNO-406 therapy. Patient 4, an accelerated phase CML treated with imatinib and nilotinib for 16 and 6 mo., respectively, before becoming intolerant to nilotinib due to thrombocytopenia, has maintained a complete hematologic response following 4.5 months of INNO-406 therapy at a dose of 120 mg/day. Patient 1, a chronic phase CML treated with imatinib for 51 mo. before developing resistant disease without a mutation, has maintained stable white cell counts after 4 months of therapy at a dose of 30–60 mg/day, with a 55-fold reduction in Bcr-Abl transcript levels after 1 month of INNO-406 therapy. Conclusions: INNO-406 is well tolerated in patients at a dose of 240 mg/day, with encouraging evidence of clinical activity in imatinib-resistant and nilotinib-intolerant patients. In the absence of dose limiting toxicity, dose escalation continues. No significant financial relationships to disclose.