PKC, Ras, and ERK1/2 signaling is pivotal to differentiation along the neuronal cell lineage. One crucial protein that may play a central role in this signaling pathway is the Ras GTPase-activating protein, neurofibromin, a PKC substrate that may exert a positive role in neuronal differentiation. In this report, we studied the dynamics of PKC/Ras/ERK pathway signaling, during differentiation of SH-SY5Y neuroblastoma cells upon treatment with the PKC agonist, phorbol ester 12-O-tetradecanoyl-phorbol-13-acetate (TPA). Surprisingly, we observed that, among other PKC-dependent signaling events, TPA induced a rapid and sustained decrease of neurofibromin immunoreactivity which was not due to proteolysis. Instead, we identified a specific phosphorylation event at the C-tail of neurofibromin. This phosphorylation was acute and correlated perfectly with the signaling dynamics of the Ras/ERK pathway. Moreover, it persisted throughout prolonged treatment and TPA-induced differentiation of SH-SY5Y cells, concurrently with sustained activation of ERK1/2. Most importantly, C-tail phosphorylation of neurofibromin correlated with a shift of neurofibromin localization from the nucleus to the cytosol. We propose that PKC-dependent, sustained C-tail phosphorylation is a requirement for prolonged recruitment of neurofibromin from the nucleus to the cytosol in order for a fine regulation of Ras/ERK pathway activity to be achieved during differentiation.
We hypothesized that chronic tissue stress due to interaction of alloreactive donor cells with host epithelium after allogeneic hematopoietic cell transplantation (allo-HCT) may cause genomic alterations. We therefore analyzed 176 buccal samples obtained from 71 unselected allotransplanted patients for microsatellite instability (MSI). MSI was observed in 52% of allotransplanted patients but never in 31 healthy or autotransplanted controls. The patient age, the donor age, a female-tomale transplantation and a low number of CD34 þ cells in the graft were significantly correlated with genomic instability. There was a trend for increasing risk of MSI for patients who experienced severe graft-vs-host disease. Secondary malignancy was diagnosed in five (14%) of the MSI þ and only in one (3%) MSI À patient. In an in vitro model of mutation analysis we found significant induction of frameshift mutations and DNA strand breaks in HaCaT keratinocytes co-cultured with mixed lymphocyte cultures (MLCs) but not after their exposure to interferon-c, tumor necrosis factor-a, transforming growth factor-b (TGF-b), MLC supernatant, peripheral blood mononuclear cells (PBMCs) or phytohemagglutinin-stimulated PBMC. A reactive oxygen species-mediated mechanism is implicated. The in vivo and in vitro data of our study show that alloreactions after allo-HCT may induce genomic alterations in epithelium. Progress in understanding DNA damage and repair after allo-HCT can potentially provide molecular biomarkers and therapeutic targets.
The prevalence of anemia increases with age and is frequently multifactorial. We postulated that malnutrition contributes to anemia in the elderly and is underdiagnosed. Our objective was to analyze the prevalence of anemia and its association with nutritional status in a hospitalized geriatric population. Included in this retrospective cohort study were 186 consecutive patients admitted in 1997 to a geriatric unit of a university hospital. We compared hematological and chemical blood tests routinely performed upon admission in patients with anemia (hemoglobin <120 g/l) and without anemia (hemoglobin > or = 120 g/l). Using these admission parameters, we defined a multiparameter score of malnutrition by low lymphocyte counts, decreased values of albumin, cholesterol, transferrin, cholinesterase, and zinc, iron deficiency by low transferrin saturation and normal C-reactive protein, and inflammation by increased C-reactive protein and high transferrin saturation. Of the 186 patients, 82 (44%) met the criteria for anemia on admission. In univariate analysis, patients with anemia differed significantly from patients with normal hemoglobin exhibiting lower serum values of albumin, iron, transferrin, cholesterol, cholinesterase, zinc, transferrin saturation, and lymphocyte count and higher C-reactive protein levels. Using a multiparameter score, anemia correlated significantly with parameters of malnutrition (P=0.0001) but not with iron deficiency (P=0.5) or with inflammation (P=0.08). In a multivariate logistic regression model, anemia was significantly associated with serum albumin (RR: 1.138; 95% CI: 1.056-1.227; P=0.0007), cholinesterase (RR: 1.387; 95% CI 1.122-1.714; P=0.0025), and transferrin saturation (RR: 1.05; 95% CI: 1.012-1.09; P=0.009). We conclude that malnutrition may play an important etiologic role in anemia in the elderly.
Summary
The incidence of FLT3 mutations (internal tandem duplication and Asp835) was investigated in bone marrow samples from 97 patients with myelodysplastic syndrome [(MDS); excluding cases with refractory anaemia with excess blasts in transformation] at the time of diagnosis and several time points thereafter. Three patients had FLT3 mutations at presentation. Forty‐two patients progressed to acute myeloid leukaemia (AML), including the three patients with FLT3 mutations at MDS diagnosis. Three additional patients acquired FLT3 mutations and progressed to AML in 1 month. FLT3 mutations seem to be a critical additional genetic event that transforms a minority of MDS patients to AML.
The association between mature-B phenotype and MLL abnormalities in acute lymphoblastic leukemia (ALL) is a very unusual finding; only 14 pediatric cases have been reported so far. We describe the clinical and biological characteristics and outcome of five pediatric cases of newly diagnosed B lineage ALL with MLL abnormalities and mature immunophenotype based on light chain restriction and surface Ig expression. Blasts showed variable expression of CD10/CD34/TdT. MLL abnormalities with no MYC involvement were detected in all patients by G-banding, FISH, and/or RT-PCR. Three patients were treated according to Interfant protocol, one to ALLIC-09, and one received B-NHL-BFM-2004. All patients achieved complete remission and three of them relapsed. Despite the small cohort size, it could be postulated that B lineage ALL with MLL abnormalities and mature phenotype is a distinct entity that differs both from the typical Pro B ALL observed in infants and mature B-ALL with high MYC expression.
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