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Blood, 28 May 2009, Vol. 113, No. 22, pp. 5549-5557. Prepublished online as a Blood First Edition Paper on March 24, 2009; DOI 10.1182/blood-2008-06-165068. This Article Full Text Full Text (PDF) Supplemental Tables All Versions of this Article: blood-2008-06-165068v1 113/22/5549    most recent Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Rights and Permissions Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Google Scholar Articles by Niedermeier, M. Articles by Burger, J. A. PubMed PubMed Citation Articles by Niedermeier, M. Articles by Burger, J. A. Related Collections Lymphoid Neoplasia Social Bookmarking                   What's this?  Previous Article  |  Table of Contents  |  Next Article  LYMPHOID NEOPLASIA Isoform-selective phosphoinositide 3'-kinase inhibitors inhibit CXCR4 signaling and overcome stromal cell–mediated drug resistance in chronic lymphocytic leukemia: a novel therapeutic approach Matthias Niedermeier1, Bryan T. Hennessy2, Zachary A. Knight3, Marina Henneberg1, Jianhua Hu4, Antonina V. Kurtova1, William G. Wierda1, Michael J. Keating1, Kevan M. Shokat3, and Jan A. Burger1 Departments of 1 Leukemia and 2 Systems Biology and Gynecologic Medical Oncology, University of Texas M. D. Anderson Cancer Center, Houston; 3 Department of Cellular and Molecular Pharmacology, Howard Hughes Medical Institute, University of California, San Francisco; and 4 Department of Biostatistics, University of Texas M. D. Anderson Cancer Center, Houston Phosphoinositide 3-kinases (PI3Ks) are among the most frequently activated signaling pathways in cancer. In chronic lymphocytic leukemia (CLL), signals from the microenvironment are critical for expansion of the malignant B cells, and cause constitutive activation of PI3Ks. CXCR4 is a key receptor for CLL cell migration and adhesion to marrow stromal cells (MSCs). Because of the importance of CXCR4 and PI3Ks for CLL-microenvironment cross-talk, we investigated the activity of novel, isoform-selective PI3K inhibitors that target different isoforms of the p110-kDa subunit. Inhibition with p110 inhibitors (PIK-90 and PI-103) resulted in a significant reduction of chemotaxis and actin polymerization to CXCL12 and reduced migration beneath MSC (pseudoemperipolesis). Western blot and reverse phase protein array analyses consistently demonstrated that PIK-90 and PI-103 inhibited phosphorylation of Akt and S6, whereas p110 or p110β/p110 inhibitors were less effective. In suspension and MSC cocultures, PI-103 and PIK-90 were potent inducers of CLL cell apoptosis. Moreover, these p110 inhibitors enhanced the cytotoxicity of fludarabine and reversed the protective effect of MSC on fludarabine-induced apoptosis. Collectively, our data demonstrate that p110 inhibitors antagonize stromal cell-derived migration, survival, and drug-resistance signals and therefore provide a rational to explore the therapeutic activity of these promising agents in CLL. CiteULike    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this? This article has been cited by other articles: J. A. Burger, P. Ghia, A. Rosenwald, and F. Caligaris-Cappio The microenvironment in mature B-cell malignancies: a target for new treatment strategies Blood, October 15, 2009; 114(16): 3367 - 3375. [Abstract] [Full Text] [PDF]

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