Saint Paul, MN, United States
Saint Paul, MN, United States

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Uckun F.M.,Childrens Hospital Los Angeles | Uckun F.M.,University of Southern California | Uckun F.M.,Parker Hughes Institute | Uckun F.M.,Institute for Pediatric Clinical Research | And 6 more authors.
British Journal of Haematology | Year: 2010

The present study found that the pentapeptide mimic C-61, targeting the substrate binding P-site of SYK tyrosine kinase acted as a potent inducer of apoptosis in chemotherapy-resistant SYK-expressing primary leukemic B-cell precursors taken directly from relapsed B-precursor leukaemia (BPL) patients (but not SYK-deficient infant pro-B leukaemia cells), exhibited favourable pharmacokinetics in mice and non-human primates, and eradicated in vivo clonogenic leukaemia cells in severe combined immunodeficient mouse xenograft models of chemotherapy-resistant human BPL at dose levels non-toxic to mice and non-human primates. These in vitro and in vivo findings provide proof of principle for effective treatment of chemotherapy-resistant BPL by targeting SYK-dependent anti-apoptotic blast cell survival machinery with a SYK P-Site inhibitor. Further development of C-61 may provide the foundation for therapeutic innovation against chemotherapy-resistant BPL. © 2010 Blackwell Publishing Ltd.


Uckun F.M.,University of Southern California | Uckun F.M.,Childrens Hospital Los Angeles | Uckun F.M.,Parker Hughes Institute | Ozer Z.,Childrens Hospital Los Angeles | And 5 more authors.
British Journal of Haematology | Year: 2010

SYK tyrosine kinase has emerged as a master regulator of cellular resistance to oxidative stress (OS) by mediating the activation of the anti-apoptotic nuclear factor κB and phosphatidylinositol-3 kinase/AKT pathways after OS exposure. Here, we present unprecedented experimental evidence that polo-like kinase 1 (PLK1) is the upstream regulator of SYK in B-lineage acute lymphoblastic leukaemia (ALL) cells. Selective inhibition of PLK-1 with the leflunomide metabolite analogue α-cyano-β-hydroxy-β-methyl- N-[4-(trifluoromethoxy) phenyl]-propenamide/LFM-A12 abolished the resistance of B-lineage ALL cells to OS by preventing the activation of the anti-apoptotic SYK signal transduction pathway. Notably, LFM-A12 treatments at non-cytotoxic concentrations resulted in marked augmentation of clonogenic death in resistant human B-lineage ALL cell lines challenged with OS. Further, LFM-A12 augmented OS-induced apoptosis of chemotherapy-resistant primary leukaemic cells from relapsed B-lineage ALL patients in vitro and markedly potentiated the in vivo anti-leukaemic activity of total body irradiation (TBI) against leukaemia-initiating cells in severe combined immunodeficient mouse xenograft models of B-lineage ALL. This study is the first to identify PLK1 as a regulator of SYK tyrosine kinase and a molecular target to overcome SYK-mediated resistance of B-lineage ALL cells to OS. © 2009 Blackwell Publishing Ltd.


Uckun F.M.,University of Southern California | Uckun F.M.,Childrens Hospital Los Angeles | Uckun F.M.,Parker Hughes Institute | Goodman P.,University of Minnesota | And 5 more authors.
Proceedings of the National Academy of Sciences of the United States of America | Year: 2010

Here, we report that primary leukemic cells from infants with newly diagnosed B-precursor leukemia express a truncated and functionally defective CD22 coreceptor protein that is unable to transmit apoptotic signals because it lacks most of the intracellular domain, including the key regulatory signal transduction elements and all of the cytoplasmic tyrosine residues. Expression of this structurally and functionally abnormal CD22 protein is associated with a very aggressive in vivo growth of patients' primary leukemia cells causing disseminated overt leukemia in SCID mice. The abnormal CD22 coreceptor is encoded by a profoundly aberrant mRNA arising from a splicing defect that causes the deletion of exon 12 (c.2208-c.2327) (CD22ΔE12) and results in a truncating frameshift mutation. The splicing defect is associated with multiple homozygous mutations within a 132-bp segment of the intronic sequence between exons 12 and 13. These mutations cause marked changes in the predicted secondary structures of the mutant CD22 pre-mRNA sequences that affect the target motifs for the splicing factors hnRNP-L, PTB, and PCBP that are up-regulated in infant leukemia cells. Forced expression of the mutant CD22ΔE12 protein in transgenic mice perturbs B-cell development, as evidenced by B-precursor/B-cell hyperplasia, and corrupts the regulation of gene expression, causing reduced expression levels of several genes with a tumor suppressor function. We further show that CD22ΔE12-associated unique gene expression signature is a discriminating feature of newly diagnosed infant leukemia patients. These striking findings implicate CD22ΔE12 as a previously undescribed pathogenic mechanism in human B-precursor leukemia.


Qazi S.,Parker Hughes Institute | Qazi S.,Gustavus Adolphus College | Uckun F.M.,Parker Hughes Institute | Uckun F.M.,Childrens Hospital Los Angeles | Uckun F.M.,University of Southern California
British Journal of Haematology | Year: 2010

This study compared the gene expression profiles of primary leukaemic cells from infants versus children with acute lymphoblastic leukaemia (ALL). Our analyses provided unprecedented evidence that remarkably different pathognomonic transcriptomes dominate the biology of infant versus paediatric high risk ALL. The genetic signature of infant ALL is characterized by concomitant overexpression of mitogenic and anti-apoptotic genes, some of which have been associated with early relapse in ALL. Our study demonstrated that primary leukaemia cells from infant ALL patients expressed significantly higher levels of genes for cytokines that mediate their biological effects through stimulation of the JAK-STAT signal transduction pathway including interleukin 1a, interleukin 1b, interleukin 2, and interleukin 7. We further showed that the JAK/STAT signalling pathway is constitutively active in CD10- infant ALL cells and treatment with a JAK3 inhibitor or a pan-JAK kinase inhibitor effectively triggered their apoptosis. These findings identified JAK3 as an attractive molecular target for disrupting the constitutively deregulated anti-apoptotic STAT3 and STAT5 signalling pathways in infant ALL cells. © 2010 Blackwell Publishing Ltd.


Uckun F.M.,Childrens Hospital Los Angeles | Uckun F.M.,University of Southern California | Uckun F.M.,Parker Hughes Institute | Sun L.,Parker Hughes Institute | And 6 more authors.
British Journal of Haematology | Year: 2011

We report the cloning and characterization of a novel 54-kDa high-mobility group (HMG)-box protein as the ligand for the human pan-B cell co-receptor CD19 (CD19-L), which interacts with the extracellular domain of CD19 in trans. CD19-L is the first CD19-specific recombinant human protein with potent anti-leukaemic activity against B-lineage acute lymphoblastic leukaemia (ALL), the most common form of childhood cancer and the second most common form of acute leukaemia in adults. Soluble recombinant CD19-L protein exhibited exquisite specificity for the extracellular domain of CD19 and strong binding to the surface of B-lineage leukaemia/lymphoma cells. Engagement of CD19 co-receptor on B-lineage ALL cells with CD19-L perturbed the CD19-associated signalling network, altering the expression levels of multiple genes directly involved in regulation of apoptosis, and triggered rapid apoptotic cell death in a CD19-specific manner. The identification of human CD19-L may lead to therapeutic innovation for B-lineage ALL and other B-lineage lymphoid malignancies as well as B-cell lymphoproliferative states and systemic autoimmunity. © 2011 Blackwell Publishing Ltd.


Qazi S.,Gustavus Adolphus College | Qazi S.,Parker Hughes Institute | Qazi S.,Childrens Hospital Los Angeles | Uckun F.M.,Parker Hughes Institute | And 2 more authors.
Journal of AIDS and Clinical Research | Year: 2012

Here we report that our lead anti-retroviral (ARV) drug candidate Stampidine [2,'3'-didehydro-3'-deoxythymidine-5'-(p-bromophenyl methoxy alaninyl phosphate)] results in methylation of a network of HIV-responsive regulatory genes in T-cells, including several genes for HIV-dependency factors (HDFs). Stampidine epigenetically modulates the host transcriptome in a unique manner, silences expression of a distinct set of genes encoding transcription factors and signal transduction molecules, and prevents HIV infection from distorting and disrupting key cellular transcriptional networks. At nanomolar concentrations that are 4-logs lower than those achieved at its non-toxic dose levels in mice, rats, cats, and dogs, Stampidine switched off genes for several HDFs that are required for HIV replication in T-cells. Notably, Stampidine reversed the effects of HIV exposure on the host transcriptome regardless of NRTI-sensitivity or RT mutations of the HIV isolate used and inhibited the replication of 17 NRTI-resistant HIV- 1 strains, including recombinant HIV clones containing common patterns of RT mutations responsible for NRTI resistance, in human peripheral blood mononuclear cells (PBMC) with subnanomolar-nanomolar IC50 values (Mean ± SEM = 12.0 ± 3.2 nM). Unlike available ARV agents that disrupt a specific step in the life-cycle of HIV, Stampidine has the potential to abrogate all steps in the life cycle of HIV. © 2012 Qazi S, et al.


Uckun F.M.,Childrens Hospital Los Angeles | Uckun F.M.,University of Southern California | Uckun F.M.,Parker Hughes Institute | Qazi S.,Gustavus Adolphus College | And 4 more authors.
Integrative Biology (United Kingdom) | Year: 2013

The t(1;19)(q23;p13) is one of the most common chromosomal translocations in acute lymphoblastic leukemia (ALL) and results in production of the transforming oncoprotein E2A-PBX1. Here we first report a novel, biomarker-guided biotherapy strategy for personalized treatment of t(1;19) + ALL. A supervised interrogation of the gene expression profiles of primary leukemic cells from a cohort of 207 children with high risk B-lineage ALL identified up-regulated CD19 gene expression as a biomarker for t(1;19) + ALL. A disulfide-linked immunoconjugate of a 5-amino-modified 24 mer phosphorothioate anti-sense E2A-PBX1 oligonucleotide (AON) with a mAb specific for a CD19 receptor (αCD19-AON) was prepared as a CD19-directed and leukemia-specific biotherapeutic agent against E2A-PBX1+ B-lineage ALL. Treatment of E2A-PBX1+ leukemia cells with low nanomolar concentrations of αCD19-AON resulted in selective depletion of E2A-PBX1 transcripts and caused apoptotic destruction and abrogation of clonogenic growth. Subcutaneously administered αCD19-AON at a total dose level of 93 nmol kg-1 delivered over 14 days using a micro-osmotic pump more than doubled the leukemia-free survival time of SCID mice in a xenograft model of E2A-PBX1+ human B-lineage ALL (82.0 ± 1.9 days vs. 37.0 ± 0.1 days, P < 0.0001). Both the AON moiety and the targeting CD19-specific mAb moiety were required for the in vitro as well as in vivo anti-leukemic activity of αCD19-AON. The observed in vitro and in vivo anti-leukemic potency of the αCD19-AON immunoconjugate provides the first preclinical proof-of-principle that t(1;19)+ high risk B-lineage ALL can be treated with leukemia-specific biotherapeutic agents that knock-down E2A-PBX1 expression. © 2013 The Royal Society of Chemistry.


Uckun F.M.,University of Southern California | Uckun F.M.,Parker Hughes Institute | Qazi S.,Parker Hughes Institute | Qazi S.,Gustavus Adolphus College | And 5 more authors.
Proceedings of the National Academy of Sciences of the United States of America | Year: 2010

We provide unprecedented genetic and biochemical evidence that the antiapoptotic transcription factor STAT3 serves as a substrate for SYK tyrosine kinase both in vitro and in vivo. Induction of SYK in an ecdysone-inducible mammalian expression system results in STAT3 activation, as documented by tyrosine phosphorylation and nuclear translocation of STAT3, as well as amplified expression of several STAT3 target genes. STAT3 activation after oxidative stress (OS) is strongly diminished in DT40 chicken B-lineage lymphoma cells rendered SYK-deficient by targeted disruption of the syk gene. Introduction of a wild-type, C-terminal or N-terminal SH2 domain-mutated, but not a kinase domain-mutated, syk gene into SYK-deficient DT40 cells restores OS-induced enhancement of STAT-3 activity. Thus, SYK plays an important and indispensable role in OS-induced STAT3 activation and its catalytic SH1 domain is critical for this previously unknown regulatory function. These results provide evidence for the existence of a novel mode of cytokineindependent cross-talk that operates between SYK and STAT3 pathways and regulates apoptosis during OS. We further provide experimental evidence that SYK is capable of associating with and phosphorylating STAT3 in human B-lineage leukemia/lymphoma cells challenged with OS. In agreement with a prerequisite role of SYK in OS-induced STAT3 activation, OS does not induce tyrosine phosphorylation of STAT3 in SYK-deficient human proB leukemia cells. Notably, inhibition of SYK with a small molecule drug candidate prevents OS-induced activation of STAT3 and overcomes the resistance of human B-lineage leukemia/lymphoma cells to OS-induced apoptosis.


Uckun F.M.,University of Southern California | Uckun F.M.,Parker Hughes Institute | Dibirdik I.,University of Southern California | Dibirdik I.,Parker Hughes Institute | Qazi S.,Gustavus Adolphus College
Radiation Research | Year: 2010

A novel spleen tyrosine kinase (SYK) P-site inhibitor, 1,4-Bis (9-O dihydroquinidinyl) phthalazine/hydroquinidine 1,4-phathalazinediyl diether (C-61), (but not vehicle) markedly enhanced H2O2-induced apoptosis of primary leukemia cells from each of five relapsed B-lineage acute lymphoblastic leukemia (ALL) patients, as measured by in vitro TUNEL assays. A highly radiation-resistant subclone of the murine B-lineage leukemia cell line BCL-1 was next used to investigate the in vivo radiosensitizing effects of C-61. C-61 enhanced the antileukemia potency of 7 Gy total-body irradiation (TBI) in the context of syngeneic bone marrow transplantation (BMT) at 20 of its nonobservable adverse effect level (NOAEL) that does not exhibit detectable single-agent activity against BCL-1 leukemia in vivo. Based on this preclinical proof-of-principle study, we hypothesize that the incorporation of C-61 into the pretransplant TBI regimens of patients with recurrent or high-risk B-lineage acute lymphoblastic leukemia (ALL) will help overcome the radiochemotherapy resistance of their leukemia cells and thereby improve their treatment response and survival outcome after BMT. © 2010 by Radiation Research Society.


Uckun F.M.,University of Southern California | Uckun F.M.,Parker Hughes Institute | Dibirdik I.,Parker Hughes Institute
Nutrition and Cancer | Year: 2010

The effects of the rationally designed JAK3 inhibitor JANEX-1 on the development of intestinal tumors in the APCmin mouse model of familial adenomatous polyposis were examined. At a non-toxic dose level, >4 times lower than its day 30 LD10, JANEX-1 was highly effective in preventing intestinal tumor development in Min mice, resulting in markedly improved survival outcomes. JAK3 inhibitors may, therefore, be useful in the chemoprevention of colorectal cancer. Here, an overview regarding the potential of JANEX-1 as a chemopreventive agent is provided. Copyright © 2010, Taylor & Francis Group, LLC.

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