e clinical data determined that inhibition of aurora A and aurora B kinases simultaneously produced EX 527 Sirtuin inhibitor a biologic effect and phenotype similar to aurora B kinase inhibition alone.20 However, no clinical data in humans have shown specific AKIs to be more or less therapeutically valuable than multi or pan aurora inhibitors. Evidence of clinical activity of Aurora inhibitors by malignancy and study design are highlighted in Table 2. Emerging data indicate that combination with spindle poisons, such as taxanes or vinca alkaloids, with aurora A kinase inhibitors may prove synergistic.14,21 Similarly, due to interaction of aurora B kinase with histone H3, combination with histone deacetylase inhibitors with AKIs inhibitors may prove synergistic.
22 Therapeutic dosing of aurora kinase specific agents may be difficult to elucidate as higher doses of AKIs may lead to a pan aurora inhibitory effect. 2.1 Selective Inhibitors of Aurora A Kinase 2.1.1 ENMD 981693 and ENMD 2076 The molecule initially described as ENMD 981693 was further developed into ENMD 2076, the L tartrate salt of ENMD 981693.23 ENMD Masitinib 2076 is more selective for aurora A kinase than ENMD 981693, with an IC50 value of 14 nM for aurora A kinase and 350 nM for aurora B kinase, respectively.24 Furthermore, ENMD 2076 also inhibits FGFR3, PDGFR, VEGFR1, and potently inhibits FLT3 with IC50 values ranging from 0.04 �?21 M. Pre clinical studies of ENMD 2076 in murine models have shown promise for multiple myeloma , breast cancer, leukemia and colorectal cancer. 24,25,26,27 Additionally, several phase I and II trials are currently ongoing in ovarian cancer, acute leukemia and multiple myeloma.
28 Green et al. Page 3 Recent Pat Anticancer Drug Discov. Author manuscript, available in PMC 2011 February 15. NIH PA Author Manuscript NIH PA Author Manuscript NIH PA Author Manuscript ENMD 2076 displays favorable pharmacokinetic profile as it is approximately 90% protein bound, displays no significant inhibition of cytochrome P450 isoenzymes CYP1A2, 2A6, 2C19, or 3A4/5 and is orally bioavailable.25,26 The spectrum of antiproliferative, antiangiogenic and cell cycle effects, combined with favorable pharmacokinetic profile makes this agent appealing for investigation in a myriad of tumor types. 2.1.2 MK 5108 MK 5108, also known as VX 689, is a competitive inhibitor of the ATPbinding site of aurora A kinase.
Pre clinical studies show efficacy in a variety of breast, cervix, colorectal, ovary, and pancreas neoplasms. This antitumor effect was enhanced by the addition of docetaxel in vitro and in vivo a murine model with acceptable toxicity, irrespective of treatment sequence.29 The combination of MK 5108 and the HDACI, vorinostat, was investigated in multiple lymphoma cell lines.22 The addition of MK 5108 to vorinostat sensitized the cell lines to apoptosis, with inhibition of c Myc playing a crucial role. A phase 1 study in patients with advanced solid tumors investigated the toxicities of singleagent MK 5108 and MK 5108 in combination with docetaxel 60mg/m2 IV every 21 days.30 Febrile neutropenia and myelotoxicity was identified as the dose limiting toxicity in combination patients, but no DLT was identified in the monotherapy arm.
Disease stabilization was seen in 11 of 34 patients from both arms, while partial response was seen in 2 of 17 patients in the combination arm and 0 of 17 in the monotherapy arm. 2.1.3 MLN8054 MLN8054 potently inhibits aurora A kinase by competitively blocking the ATP binding pocket. Importantly, MLN8054 is structurally and functionally similar to benzodiazepines, leading to the DLT of somnolence at clinically relevant doses.31,32 Preclinical studies in a several cell culture and murine xenograft models displayed potent antitumor activity as determined by di

of angiogenesis is VEGF. Various studies have shown it to be a potent stimulator of angiogenesis in vitro. Because of its critical role in angiogenesis, it has been targeted for controlling tumor progression. Limiting VEGF in tumors has been shown to lead to blood vessel destruction and to Pazopanib Armala prevent the growth of new ones, thus reducing the blood supply to the tumor. Inhibition of the VEGF tyrosine kinase signaling pathway blocked angiogenesis in growing tumors, leading to stasis and regression of the tumors. Thus, agents that can downregulate or inhibit the expression of VEGF or its signaling pathway in tumor cells could prove to be very promising in preventing tumor growth and metastasis. Saikosaponin C, one of the saikosaponins present in a Chinese herb, Radix bupleuri, has been found to have a potent inducing effect on human umbilical vein endothelial cells, viability and growth.
Saikosaponin C also induced endothelial cell migration and capillary tube formation. Saikosaponin C induced the gene expression or activation of MMP2, VEGF, and the p42/p44 MAPK that correlates with endothelial cell growth, migration, and angiogenesis, respectively. Dienogest Another study found that saikosaponins can inhibit the physiological angiogenesis of chicken embryos, especially for the medium and small vessels. CDDO Me and CDDO Im were shown to inhibit the activation of the ERK1/2 pathway after stimulation with VEGF in human umbilical vein endothelial cells. CDDO Me also potentiated the cytotoxic effects of TNF and chemotherapeutic agents.
This may be because CDDO Me inhibits NF κB through the inhibition of IκB kinase, leading to the suppression of NF κB regulated gene product expression and to angiogenesis. Boswellic acids Toxins 2010, 2 2449 suppressed VEGF induced phosphorylation of VEGF receptor 2 kinase with an IC50 of 1.68 M. Specifically, boswellic acids suppressed the downstream protein kinases of VEGFR2, including Src family kinase, focal adhesion kinase, ERK, AKT, mTOR, and ribosomal protein S6 kinase. In an ex vivo model, boswellic acids significantly inhibited blood vessel formation in the Matrigel plug assay in mice and effectively suppressed VEGF induced microvessel sprouting in a rat aortic ring assay. Furthermore, boswellic acids inhibited VEGF induced cell proliferation, chemotactic motility, and the formation of capillary like structures from primary cultured human umbilical vascular endothelial cells in a dose dependent manner.
Betulinic acid also inhibits growth factor induced in vitro angiogenesis by modulating mitochondrial function in endothelial cells. Various in vivo studies have found that celastrol can downregulate the density of tumor microvessels significantly at different doses. Immunohistochemistry showed that celastrol also decreased the levels of VEGFR1 and VEGFR2 expression, but not the level of VEGF expression. However, avicins, downregulate the expression of VEGF. An in vivo study showed that Ganoderma lucidum given at 100 and 200 mg/kg inhibited primary solid tumor growth in the spleen, liver metastasis, and secondary metastatic tumor growth in the liver in intrasplenic Lewis lung carcinoma implanted mice.
An in vivo assay system extract inhibited Matrigel induced angiogenesis. 5. Role of Triterpenoids in Cancer Treatment Triterpenoids are structurally diverse organic compounds. More than 20,000 triterpenoid varieties are formed by multiple modifications of the basic backbone structure. Several triterpenoids such as avicin, betulinic acid, boswellic acids, celastrol, diosgenin, madecassic acid, maslinic acid, momordin, saikosaponins, platycodon, pristimerin, ursolic acid, CDDO, and withanolide, have been shown in our laboratory and others to possess anticancer and anti inflammatory activities. Preliminary data from on

Author manuscript, available in PMC 2011 July 23. NIH PA Author Manuscript NIH PA Author Manuscript NIH PA Author Manuscript Figure 2. Withanolide A down regulates BACE1 and up regulates ADAM10. Cortical neurons were treated with 0, 5, 20 and 100 M of 1 for bcl-2 family 24 h. Immunoblots show significant downregulation in BACE1 levels and also up regulation of active ADAM10 levels in neurons treated with 1 as compared to respective controls. Histograms corresponding to BACE1 and ADAM10 blots represent quantitative determinations of intensities of the relevant bands normalized to actin. Data represent the mean S.D. of three independent experiments. The Student,s t test was used for analyzing the differences between the two treatment groups. Patil et al. Page 13 J Nat Prod. Author manuscript, available in PMC 2011 July 23.
NIH PA Author Manuscript NIH PA Author Manuscript NIH PA Author Manuscript Figure 3. Asiatic acid down regulates BACE1 and up regulates ADAM10. Cortical neurons buy BIBR 1532 were treated with 0, 1, 5 and 10 M of 2 for 24 h. Immunoblots show significant down regulation in BACE1 levels as well as up regulation of mature ADAM10 levels in neurons treated with 2 as compared to respective controls. Histograms corresponding to BACE1 and ADAM10 blots represent quantitative determinations of intensities of the relevant bands normalized to actin. Data represent the mean S.D. of three independent experiments. The Student,s t test was used for analyzing the differences between the two treatment groups. Patil et al. Page 14 J Nat Prod. Author manuscript, available in PMC 2011 July 23.
NIH PA Author Manuscript NIH PA Author Manuscript NIH PA Author Manuscript Figure 4. Effects of 1 and 2 on APP processing. Immunoblots show a dose dependent increase in the levels of C83 and sAPP in neurons treated with 1 and 2 as compared to their respective controls. Histograms corresponding to sAPP blot represent quantitative determinations of intensities of the relevant bands normalized to actin. Data represent mean S.D. of three independent experiments. The Student,s t test was used for analyzing the differences between the two treatment groups. Patil et al. Page 15 J Nat Prod. Author manuscript, available in PMC 2011 July 23. NIH PA Author Manuscript NIH PA Author Manuscript NIH PA Author Manuscript Figure 5. Dose dependent effects of withanolide A on targets involved in A degradation.
Cortical neurons were treated with 0, 5, 20 and 100 M of 1 for 24 h. Immunoblots show significant up regulation of IDE, while NEP remained unaffected, in neurons treated with 1 in a dose dependent manner as compared to controls. Histograms corresponding to IDE and NEP blots represent quantitative determinations of intensities of the relevant bands normalized to actin. Data represent mean S.D. of three independent experiments. The Student,s t test was used for analyzing the differences between the two treatment groups. Patil et al. Page 16 J Nat Prod. Author manuscript, available in PMC 2011 July 23. NIH PA Author Manuscript NIH PA Author Manuscript NIH PA Author Manuscript Asiatic Acid, a Pentacyclic Triterpene From Centella asiatica, Is Neuroprotective in a Mouse Model of Focal Cerebral Ischemia Rajanikant G.
Krishnamurthy1, Marie Claude Senut1, Daniel Zemke1, Jiangyong Min1, Mark B. Frenkel1, Eric J. Greenberg1, Seong Woon Yu1,2, Nick Ahn1,2, John Goudreau1,2, Mounzer Kassab1, Kiran S. Panickar3, and Arshad Majid1, 1Division of Cerebrovascular Diseases and Department of Neurology and Ophthalmology, Michigan State University, East Lansing, Michigan 2Department of Pharmacology and Toxicology, Michigan State University, East Lansing, Michigan 3Diet, Genomics, and Immunology Laboratory, United States Department of Agriculture, Beltsville, Maryland Abstract Asiatic acid, a triterpenoid d

e isoforms of PI3K. Cross-linking of the FcεRI by multivalent Ag is known to activate a Tyr kinase signaling cascade, which provides a direct molecular link to class IA PI3K signaling. Genetic or pharmacological inactivation of p110δ has been shown to lead to a substantial, but not complete, block in the allergic responses in mice. Surprisingly, genetic inactivation A 922500 959122-11-3 of p110γ in mice has been reported to lead to a complete block in passive cutaneous and systemic anaphylaxis responses in vivo. This is remarkable, given that the FcεRI Tyr kinase signaling pathway does not appear to provide a direct molecular link to this GPCRcoupled PI3K.
Evidence has been presented for p110γ being part of an auto/paracrine mechanism whereby exocytosed mast cell-derived GPCR agonists, initially released by an FcεRI-dependent Aloe-emodin inhibitor pathway, promote hyperactivation of mast cells through GPCR signaling to overcome inhibition by the lipid phosphatases SHIP and PTEN, which antagonize PI3K signaling. Differences in experimental procedures, especially when using model organisms such as mice, often make it difficult to directly compare data from different laboratories. We have therefore directly compared side-by-side the roles of the p110γ and p110δ isoforms of PI3K in mast cell signaling in vitro and in the allergic immune response in vivo. For this, we have used PI3K mutant mice on the same genetic background, as well as a panel of newly developed small molecule inhibitors against PI3K isoforms. We find that in vitro, both p110γ and p110δ are important for IgE/Ag-dependent mast cell activation.
In vivo, however, IgE/Agtriggered allergic responses appear to a large extent driven by p110δ and are not dependent on p110γ. These findings have implications for the ongoing development of small molecule-PI3K inhibitors for allergy and inflammation. Materials and Methods Mice Mice in which p110γ or p110δ have been inactivated have been described previously. Mice were backcrossed onto a C57BL/6 genetic background for 10 generations. Agematched, 6�?0-wk-old mice were used for all experiments. C57BL/6 mice were used for pharmacological experiments. All protocols involving live animals were approved by the United Kingdom Home Office and local ethical review committee. Small molecule inhibitors Compounds used were: TGX-155 ), IC87114 ), and AS-605240, AS-604850 and AS-252424.
Compound or vehicle ) were 4Abbreviations used in this paper: GPCR, G protein-coupled receptor; BMMC, bone marrow-derived mast cell; HSA, human serum albumin; i.d., intradermal; KO, knockout; PCA, passive cutaneous anaphylaxis; SCF, stem cell factor; WT, wild type; Tyr, tyrosine; PKB, protein kinase B. Ali et al. Page 2 J Immunol. Author manuscript; available in PMC 2009 February 16. UKPMC Funders Group Author Manuscript UKPMC Funders Group Author Manuscript administered per os 1 h before Ag challenge. PI3K inhibitors were tested at 30 mg/kg and administered 1 h before Ag challenge. Mast cell culture Mast cell precursors were isolated from bone marrow of 6-wk-old C57BL/6 male mice, as described , and maintained in RPMI 1640 medium containing 10% ultra-low IgG FBS , penicillin and streptavidin, glutamine and 20 ng/ml recombinant mouse stem cell factor , and 20 ng/ml IL-3 for at least 4 wk and with culture times not exceeding 8 wk.
Expression of FcεRI and Kit were confirmed by flow cytometry as described. Assessment of Akt/protein kinase B phosphorylation in mast cells in vitro For stimulations with adenosine or SCF, cells were starved for 3 h in serum- and cytokine-free medium. Cells were then treated with compound or 0.5% DMSO for 15 min, followed by stimulation with SCF or adenosine. Ce

y U test with results of analysis and animal numbers presented in the relevant figure legends. The differences between wild-type and mutant animals or untreated and treated groups were statistically not significant if p 0.05 , significant if p 0.05 , very significant if A-769662 p 0.01 , and extremely significant if p 0.001. In vitro data were analyzed by nonparametric t test. GraphPad Prism software was used for all statistical analysis. Results Mouse lines used in this study were as follows. Mice which lack expression of p110γ as a consequence of gene deletion/knockout are referred to as γKO. Mice expressing a germline mutation encoding a kinase-dead version of p110δ are referred to asδD910A. Both mouse lines were backcrossed onto the C57BL/6 genetic background for 10 generations.
For genetic studies, Nutlin-3 the WT control mice were derived from inter-crosses of mice heterozygous for the p110 mutations. C57BL/6 WT mice from commercial breeders were used for pharmacological experiments. Isoform-selective PI3K inhibitors and their IC50 for the different PI3Ks are listed in Table I. In vivo doses for each inhibitor were established previously taking into account pharmacokinetic profiles. p110δ activity is important for the development or maintenance of tissue site-specific mast cell population We previously reported that genetic inactivation of p110δ leads to a reduction in mast cell numbers in specific tissues, such as the dermis of the ear and the submucosal and muscularis layers of the stomach. Mast cell numbers in other tissues, such as the dermis of the back and the mucosa layer of the stomach, were unaffected ; Fig.
1A). We have now also assessed the impact of p110γ deletion on mast cell numbers and found comparable mast cell numbers in γKO and WT mice at all anatomical sites assessed, in line with previously published data on a more limited set of tissues. Only the dermis of the back skin showed a minor reduction of toluidine blue-positive mast cells in p110γKO mice. These data Ali et al. Page 4 J Immunol. Author manuscript; available in PMC 2009 February 16. UKPMC Funders Group Author Manuscript UKPMC Funders Group Author Manuscript show that p110δ, unlike p110γ, has an impact on mast cell differentiation, which should be taken into account when interpreting studies using δD910A mice.
Inactivation of p110γ or p110δ does not affect vascular responsiveness to proinflammatory stimuli Recently, evidence has been presented for the presence of p110γ and p110δ in endothelial cells and vascular smooth muscle cells. Given that allergic responses in p110γ and p110δmutant mice have been assessed by leakage of Evans blue out of the vessels , it is not clear to what extent altered vascular responsiveness of PI3K mutant mice may have contributed to the observed reduced allergic responses in these mice. To gain insight into this question, we tested the direct effect of vasoactive compounds on vascular permeability in mutant mice, again using leakage of Evans blue dye into the surrounding tissue as a read-out. Injection of histamine led to a robust increase in vascular permeability that was similar in all genotypes.
Vascular permeability responses to mast cell extracts were also similar in WT, γKO, and δD910A mice. Taken together, these data show an intact responsiveness of the vasculature to inflammatory stimuli upon systemic inactivation of p110γ or p110δ.Distinct roles for p110γ and p110δ in adenosine signaling in mast cells In line with a previous report , we find that adenosine-stimulated phosphorylation of Akt, a surrogate marker of PI3K activity, is abrogated in γKO BMMCs. In agreement with this observation, adenosine-induced Akt/

Ment-regulated transcripts: PCI-24781 MEK inhibitor Peltier et al. Page 5 J. Immunol. Author manuscript, increases available in PMC 15th June 2011. NIH-PA Author Manuscript NIH-PA Author Manuscript PA Author Manuscript NIH �� false discovery rate of 1%, three minimum coverage of the probe, and the change log 2 expression level 0.5 By contr L. In the comparison Similar results were obtained when the microarray data using Affymetrix were the Bioconductor package. The list of genes are preferably overexpressed in differentiated BE-C / M cells were analyzed using Ingenuity Pathway Analysis software. This analysis used the Ingenuity Pathway Analysis library of 103 signaling and metabolic pathways to those 80 canonical order, the most important were identified in the record.
This service was measured by determining the ratio Ltnisses the number of genes from the dataset that correspond to a specific PCI-24781 HDAC inhibitor channel canonical total number of genes in this path, and calculating a value of p below using a Fischer exact test. The association with a particular metabolic pathway canon was considered significant if the p-value cDNA synthesis and real-time PCR with the manufacturer’s recommended protocols and reagents for s BioRad iCycler iQ thermocycler, and fluorescence values of the threshold cycle were analyzed using the SDS system software 700th The results were on the average Ct of five housekeeping genes listed in the table and Δ RT-PCR Ct values were calculated to determine the expression of Ver Changes normalized. Genes that have reached the maximum 35 cents in both studies were excluded from analysis. Statistical analysis of microarray and statistical analyzes are as described above. For comparative analysis, we used a bilateral student, provided that s t-test, unequal variances, where a p-value Results poly-induced activation of the PRR and IFN production β differentiated neural cells for the first activity T of the nerve pathway PRR study we used the previously characterized human BE-C model neuronal culture. The neuroblastoma cell line in the presence of S Acid retino be distinguished Such cells to form with morphological, biochemical and physiological mature human nerve cells, and was used to show the responses differentiationdependent of human neuronal cells, stimulation of type I IFN and neurotropic viral infection. We generated stable cell lines containing either an NF B promoter κ mechanical or IRSE SEAP promoter-reporter gene driven differentiation of S Acid-induced retinopathy That, and examined the reporter activity t in Kultur��berst The tissue cells with poly, which is a dsRNA mimetic and potent inducer of PRR pathway activation stimulated.
We used increasing concentrations of extracellular Delivered to the cell surface poly rem Surface or endosomal TLR activation or complexed with lipofectamine transfected in order to stimulate intracellular Re RLR and evaluation of responses in both undifferentiated and differentiated cell lines BE C. Both NF expressing B and ISRE promoter-driven reporters κ was found that significant dose in differentiated C / m cells with both extracellular Ren and transfected poly, w while almost no reaction in undifferentiated cells were observed. Calculated concentrations, the poly 50% of the maximum reaction-C produced in differentiated / m between cells were ~ 10 ng / ml and 10 μ g / ml The inabilit

Substrate, filled in the middle of the cell and the upper part of the cell. n � �� �, * p ZSTK474Cell2 a cell 3 cell 4 cell 5 0 20 40 60 80 100 120 0 20 40 60 80 100 mobile phone Cell2 a cell 3 cell 4 cell 5 0 2 4 6 8 10 12 A Susp Susp Adh Adh SHIP1 IP: SHIP1 4G10 No fMLP with fMLP B Susp Adh SHIP1 IP: SHIP1 b3 integrin FAK Lyn remote R & D intensity t in the z-axis at the bottom of the intensity t Relative greater than the distance from the axis E z * C bottom top SHIP1% PtdInsP3 actin dephosphorylation 0 20 40 60 80 100 120 in the lower center of the upper Unlk fertilization adherent SHIP1 intensity F t * 1224 | S. Mondal et al . Molecular biology of the cell, the cell migration process includes Zelladh Commission, indicated the involvement of integrin lead to the formation of binding sites on PtdInsP3.
Above the production of Strength PtdInsP3 the bottom of a cell migration k nnte Required with the production of the front � �� osterior Masitinib PtdInsP3 gradient for cell migration. St Ren Our observations show that SHIP1 plays a role Role in the metabolism PtdInsP3 on the gel Walls of Zelladh Away mission. M can Shortcomings in chemotaxis in SHIP1 � eutrophils by reducing the Zelladh recession SHIP1 be saved EUR eutrophils show strong adversely Chtigt migration toward a source of attractant. We then business protected That if chemotaxis due to excessive cell-adhesion recession Adversely Chtigt is, we may use the chemotaxis by reducing the surface Surface to improve adhesion.
To resolve this problem, we examined neutrophil chemotaxis toward fMLP with EZ-cab scanning adhesion, we transfected Akt-PH-EGFP in neutrophils to PtdInsP3 see � �� tdInsP2 wild-type and SHIP1 eutrophils �. They lie the cells on a surface impact area, coated with fibronectin. The cells were fixed and using high res Send confocal microscopy of cutting. SHIP1 � eutrophils had a significant accumulation of Akt-PH-EGFP in the cell cortex. Of interest, disclose side view projection of images in cross section, that mission may need during the Adh, Akt-PH-EGFP on the plasma membrane of neutrophils wild type, but is in SHIP1 eutrophils �, there is a strong enrichment at the interface cell � �s ubstratum. Since the loss SHIP1 prevent the formation of PtdInsP2 PtdInsP3 would enrichment was act-PH-EGFP formed primarily on an h Higher level of PtdInsP3 at the point of attachment.
High concentrations of PtdInsP3 are indeed the decisive factor for the increased Hte Adh Sion of cells and activation of Akt in the Zelladh Sion in SHIP1 eutrophils �. These results suggest that even during the w pro-FIG 4: Adhesion-mediated signal transmission is being strengthened in PtdInsP3 SHIP1 EUR eutrophils verst. Wild-type or SHIP1 � �o r wild-type PTEN or � eutrophils were either unstimulated or stimulated with 1 M fMLP suspended or just to keep the coating on a surface Surface with fibronectin for 15 min cells , and not adhering kidnapped min and then stimulated with fMLP for 2. The phospho-Akt were analyzed in cell lysates. Total Akt was used as a contr The load.
Wild-type or SHIP1 � eutrophils were transfected with Akt-PH-EGFP and you lie keep it on a surface surface coated with fibronectin. The cells were fixed and with the help of confocal microscopy, images were reconstructed cross-sectional side view projection heavy accumulation of Akt-PH-EGFP in the cell interface � ubstratum �s shows SHIP1 eutrophils �. The intensity analyzed Of its fluorescence in the z-axis with ImageJ. Analysis of four repr Shown with representative cells for each genotype. Values of fluorescence intensity Th projection side view cross-sectional images of the wild-type and SHIP1 � �� Ellen express Akt PH-EGFP were analyzed applied ImageJ against the lower surface Surface of the touch substrate, the center of the cell, and a upper portion of the cell is bound. n � �� �, * p

nical development of such agents. However, information currently available Tortora et al. Page 12 Drug Resist Updat. Author manuscript, available in PMC 2008 September 23. NIH PA Author Manuscript NIH PA Author Manuscript NIH PA Author Manuscript does not allow to draw KU-55933 ATM inhibitor any definitive conclusion and biomarkers/predictive markers appear too premature to be the hinge driving MEK directed therapeutic programs forward at this time. 5. The MEK/ERK pathway as a therapeutic target in haematological malignancies Acute myeloid leukaemia is a deadly disease, resulting from the clonal expansion and accumulation of haematopoietic stem cells arrested at various stages of development.
Genetic aberrations that disrupt the function of haematopoietic BI 2536 755038-02-9 transcription factors play a central role in leukaemogenesis, in addition to transcription factor fusion proteins, aberrant activation of the kinase based signal transduction pathways that normally translate extracellular stimuli into appropriate homeostatic responses can powerfully contribute to leukaemogenesis by enabling leukaemic cells to grow autonomously and escape programmed cell death. A new paradigm is thus emerging, in which acute leukaemia could be modelled as comprising at least two mutational events: activation of a kinase based signaling pathway, which confers proliferative and/or anti apoptotic activity to haematopoietic cells without affecting differentiation, and a transcription factor fusion protein, which has a limited effect on cell transformation or proliferation, but impairs normal differentiation pathways.
The MAPK pathway that proceeds from Ras and its downstream effector Raf to MEK and ERK, is a key integration point along the signal transduction cascades that emanate from receptor and/or fusion protein associated tyrosine kinases and links diverse extracellular stimuli to proliferation, differentiation, and survival. We and others have recently provided substantial evidence that the MEK/ERK signaling module is frequently deregulated in myeloid leukaemias and other haematological malignancies, as a result of genetic and epigenetic aberrations involving both receptorassociated and cytoplasmic tyrosine kinases, as well as inhibitory phosphatases. Constitutive activation of this MAPK module is particularly common in AML, where ERK phosphorylation/activation is detected in primary leukaemic blasts in 50% to 90% of patients.
Conversely, constitutive ERK activation is usually not detectable in CD34 haematopoietic bone marrow progenitors from healthy donors or from leukaemic patients in complete remission. Most interestingly, from a clinical standpoint, both retrospective and prospective analyses of pERK levels in primary blasts obtained at diagnosis from AML patients indicate that high pERK levels are an independent predictor of worse overall survival, as a result of a combination of lower remission rates, shorter remission durations, and higher relapse rates. Limited information is available, at this time, on the presence and role of constitutive ERK signaling in acute lymphoblastic leukaemia. Constitutive ERK activation in ALL cell lines and in a limited number of clinical ALL specimens has been reported, together with suggestion that elevated pERK levels may be prognostic for survival. We have recently analysed constitutive ERK phosphorylation by flow cytometry in the largest series of primary adult ALL samples reported so far and found that approximately 30% of cases express pERK, cons

atran 150 and 220 mg and 1.4% for enoxaparin. In a BSI-201 Iniparib pooled analysis of the RE MODEL, RE MOBILIZE, and RE NOVATE studies, major VTE and VTE related death occurred in 3.3% of the enoxaparin group versus 3.0% of the dabigatran etexilate 220 mg group and 3.8% of the dabigatran etexilate 150 mg group. Major bleeding events were infrequent, and occurred at similar rates across all groups: enoxaparin 1.4%, dabigatran etexilate 220 mg 1.4%, and dabigatran etexilate 150 mg 1.1%. In summary, dabigatran has demonstrated non inferiority and a similar safety profi le to enoxaparin for VTE prevention after THR, and represents a viable, orally administered alternative to enoxaparin in this setting. The results for VTE prevention after TKR are less conclusive.
Dabigatran demonstrated non inferiority to enoxaparin in one phase III study but not in another, although it should be noted that different enoxaparin BIIB021 dosing regimens were used in each of these studies, bleeding rates with dabigatran were similar to enoxaparin in both studies. Based on the results of phase III studies, dabigatran has recently been approved in the European Union for the prevention of VTE following major orthopaedic surgery in adults. Dabigatran is currently being investigated in three further phase III trials: RE LY, a study comparing the effi cacy and safety of dabigatran with warfarin for the prevention of stroke and systemic embolism in patients with non valvular AF, RE COVER, a randomized study comparing the effi cacy and safety of dabigatran etexilate with warfarin for the treatment of acute symptomatic VTE, following initial treatment with a parenteral anticoagulant, and RE MEDY, a randomized, active controlled study to evaluate the effi cacy and safety of oral dabigatran etexilate compared with warfarin, for the secondary prevention of VTE.
Rivaroxaban Rivaroxaban is a once daily, oral, direct FXa inhibitor. It selectively and competitively binds to FXa with 1:1 stoichiometry, blocking the interaction of FXa with its substrate prothrombin. Rivaroxaban binds to the active site of FXa, its chlorothiophene moiety directed into the S1 pocket, and does not require highly basic groups like amidines for FXa affi nity. Binding inhibits not only free FXa but also fi brin bound FXa and prothrombinase activity. Rivaroxaban has high bioavailability and a dual mode of elimination, with one third of the dose excreted unchanged via the kidneys, and two thirds metabolized by the liver.
Maximum plasma levels of rivaroxaban occur 2 4 hours after oral administration and elimination of rivaroxaban from plasma occurs with a terminal half life of 5 9 hours in young individuals, and 11 12 hours in the elderly . Three phase IIb trials, ODIXa HIP2, ODIXa KNEE, and ODIXa OD HIP, were initiated to investigate the antithrombotic potential of rivaroxaban for VTE prevention following major orthopaedic surgery. The primary effi cacy outcome in these trials was the composite of any DVT, non fatal PE, and all cause mortality, and the primary safety outcome was major, post operative bleeding. 1378 Vascular Health and Risk Management 2008:4 Lassen and Laux Table 3 Summary of clinical studies: prevention and treatment of venous thromboembolism Drug Phase Patient population Dosing Comparator Primary endpoint Safety endpoint Results summary VTE prevention Dabigatran etexilate BISTRO II II THR/TKR 50 225 mg bid/ 300 mg od Enoxaparin Incidence of VTE Major bleeding Primary endpoint: 28.5%, 17.4%, 13.1% and 16.6% v