A novel, somatic, transforming mutation in the extracellular domain of Epidermal Growth Factor Receptor identified in myeloproliferative neoplasm.

We describe a novel ERBB1/EGFR somatic mutation (p. C329R; c.985 T > C) identified in a patient with JAK2V617F Polycythaemia Vera (PV). This substitution affects a conserved cysteine residue in EGFR domain 2 and leads to the formation of a ligand-independent covalent receptor dimer, associated with increased transforming potential. Aberrant signalling from the EGFRC329R receptor is cell type-dependent and in the TF1.8 erythroid cell line expression of this mutant suppresses EPO-induced differentiation. Clonal analysis shows that the dominant JAK2V617F-positive clone in this PV patient harbors EGFRC329R, thus this mutation may contribute to clonal expansion. Somatic mutations affecting other ERBB and related receptor tyrosine kinases are observed in myeloproliferative neoplasms (MPN), and we show elevated EGFR levels in MPN samples, consistent with previous reports. Thus activation of this group of receptors, via multiple mechanisms, may contribute to clonal growth and survival of the JAK2V617F disease clone in MPN.

TGF-α and IL-6 plasma levels selectively identify CML patients who fail to achieve an early molecular response or progress in the first year of therapy.

Early molecular response (EMR, BCR-ABL1 (IS)⩽10% at 3 months) is a strong predictor of outcome in imatinib-treated chronic phase chronic myeloid leukemia (CP-CML) patients, but for patients who transform early, 3 months may be too late for effective therapeutic intervention. Here, we employed multiplex cytokine profiling of plasma samples to test newly diagnosed CP-CML patients who subsequently received imatinib treatment. A wide range of pro-inflammatory and angiogenesis-promoting cytokines, chemokines and growth factors were elevated in the plasma of CML patients compared with that of healthy donors. Most of these normalized after tyrosine kinase inhibitor treatment while others remained high in remission samples. Importantly, we identified TGF-α and IL-6 as novel biomarkers with high diagnostic plasma levels strongly predictive of subsequent failure to achieve EMR and deep molecular response, as well as transformation to blast crisis and event-free survival. Interestingly, high TGF-α alone can also delineate a poor response group raising the possibility of a pathogenic role. This suggests that the incorporation of these simple measurements to the diagnostic work-up of CP-CML patients may enable therapy intensity to be individualized early according to the cytokine-risk profile of the patient.

Contrasting effects of diclofenac and ibuprofen on active imatinib uptake into leukaemic cells.

BACKGROUND: The human organic cation transporter-1 (OCT-1) is the primary active protein for imatinib uptake into target BCR-ABL-positive cells. Non-steroidal anti-inflammatory drugs (NSAIDs) are frequently used by chronic myeloid leukaemia (CML) patients on imatinib to manage musculoskeletal complaints. METHODS: Here we investigated the impact of NSAIDs on functional activity of the OCT-1 (OCT-1 activity; OA) in CML cells. RESULTS: Although ten of twelve NSAIDs tested had no significant impact on OA (P>0.05), we observed increased OA (27% increase in K562; 22% increase in KU812 cells, P<0.05) and reduced IC50(imatinib) when treated with diclofenac. Co-incubation with imatinib and diclofenac resulted in a significantly lower viable cell number compared with imatinib alone. In contrast, ibuprofen led to a significant decrease in OA, an increase in IC50(imatinib) and thus reduced the cytotoxicity of imatinib. In primary CML samples, diclofenac significantly increased OA, particularly in patients with low OA (<4 ng per 200 000 cells), and significantly decreased IC50(imatinib). Ibuprofen induced significant decreases in OA in CML samples and healthy donors. CONCLUSION: On the basis of the expected impact of these two drugs on OA, ibuprofen should be avoided in combination with imatinib. Further studies are warranted regarding the potential benefit of diclofenac to improve OA in a clinical setting.

Placental transfer of SSRI and SNRI antidepressants and effects on the neonate.

INTRODUCTION: We investigated placental transfer and neurobehavioural effects in neonates exposed to citalopram, escitalopram, fluoxetine, fluvoxamine, paroxetine or sertraline (SSRI's), or to venlafaxine (an SNRI). METHODS: Women receiving antidepressants during pregnancy and their neonates were studied. Cord and maternal drug concentrations were measured at birth and in the neonates plasma on day 3. Neonates were also assessed using a range of neurobehavioral tests and compared to controls. RESULTS: Median cord/maternal distribution ratio was 0.7-0.86 (range) for SSRIs, 0.72 for the SNRI venlafaxine and 1.08 for the O-desmethyl metabolite. Neonatal abstinence scores were significantly higher (p<0.05) in exposed infants than controls on day 1. Brazelton scores for habituation, social-interactive, motor and autonomic clusters, and serotonin scores were significantly greater (p<0.05) in exposed infants. DISCUSSION: Transfer of SSRIs and SNRIs across the placenta was substantial. Neonates developed mild behavioral symptoms in the early perinatal period but these were self-limiting and similar for both SSRIs and the SNRI venlafaxine.

Repression of Gadd45alpha by activated FLT3 and GM-CSF receptor mutants contributes to growth, survival and blocked differentiation.

The tumor suppressor Gadd45alpha was earlier shown to be a repressed target of sustained receptor-mediated ERK1/2 signaling. We have identified Gadd45alpha as a downregulated gene in response to constitutive signaling from two FLT3 mutants (FLT3-ITD and FLT3-TKD) commonly found in AML, and a leukemogenic GM-CSF receptor trans-membrane mutant (GMR-V449E). GADD45A mRNA downregulation is also associated with FLT3-ITD(+) AML. Sustained ERK1/2 signaling contributes significantly to receptor-mediated downregulation of Gadd45alpha mRNA in FDB1 cells expressing activated receptor mutants, and in the FLT3-ITD(+) cell line MV4;11. Knockdown of Gadd45alpha with shRNA led to increased growth and survival of FDB1 cells and enforced expression of Gadd45alpha in FDB1 cells expressing FLT3-ITD or GMR-V449E resulted in reduced growth and viability. Gadd45alpha overexpression in FLT3-ITD(+) AML cell lines also resulted in reduced growth associated with increased apoptosis and G(1)/S cell cycle arrest. Overexpression of Gadd45alpha in FDB1 cells expressing GMR-V449E was sufficient to induce changes associated with myeloid differentiation suggesting Gadd45alpha downregulation contributes to the maintenance of receptor-induced myeloid differentiation block. Thus, we show that ERK1/2-mediated downregulation of Gadd45alpha by sustained receptor signaling contributes to growth, survival and arrested differentiation in AML.

Nonconjugative R plasmid-mediated antibiotic resistance in Escherichia coli isolated from animals in Peninsular Malaysia.

Four of the five veterinary E. coli strains, which were unable to transfer their antibiotic resistance by conjugation, were found to harbour plasmids. Evidence from transformation, agarose gel electrophoresis and curing experiments showed that in strains KE-3, KE-4 and KE-14 a nonconjugative R plasmid carried the gene for resistance to tetracycline. The plasmids in KE-9 were cryptic.

Antimicrobial resistance and conjugative R plasmids in Escherichia coli strains isolated from animals in Peninsular Malaysia.

Fifteen independent E. coli strains of avian, bovine and porcine origin in Peninsular Malaysia were tested for antibiotic resistance and conjugative R plasmids. Eight (53%) isolates were found to be antibiotic resistant. Among them, 37.5% were mono-resistant and 62.5% were resistant to three or more antibiotics, i.e., multi-resistant. All of them were resistant to Tc and sensitive to Gm and Nx. Three of the eight antibiotic resistant strains were able to transfer all or part of their resistance to an E. coli K12 recipient by conjugation. The transfer frequencies of Km, Sm and Tc resistance of the three donors varied between 4.5 X 10(-8) to 6.8 X 10(-7). Analysis of the plasmid profiles of all the three donors and their respective transconjugants after agarose gel electrophoresis provided conclusive evidence that the transferable resistance traits were plasmid-mediated.