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Recent studies indicate that abnormalities of the interleukin-3 receptor (IL-3R) are frequently observed in acute myeloid leukemias (AMLs) and may contribute to the proliferative advantage of leukemic blasts. This review analyzes the evidences indicating that the IL-3R represents one of the target molecules involved in the stimulation of proliferation of AMLs, and the overexpression of the IL-3Ra chain may represent one of the mechanisms contributing to the development of a highly malignant leukemic phenotype. Furthermore, there is evidence that the IL-3Ra is a marker of leukemic stem cells, at variance with normal stem cells that are IL-3Ra-. Finally, the IL-3R may represent an important target for the development of new antileukemic drugs.Leukemia (2004) 18, 219-226. doi:10.1038/sj.leu.2403224 Published online 4 December 2003 [ABSTRACT FROM AUTHOR]

We have investigated the expression of the M-CSF receptor (c-fms) in 16 freshly isolated acute promyelocytic leukemias (APL) expressing the PML/RARα fusion protein. In parallel, we evaluated the capacity of these cells to differentiate along the granulocytic and monocytic pathways. c-fms was constitutively and constantly expressed in all cases sensitive in vivo to all-trans retinoic acid (ATRA) and its expression was further potentiated following in vitro induction with ATRA. Furthermore, gel-shift analysis of APL cells showed elevated levels of PU.1 binding activity to the M-CSF receptor promoter, particularly after ATRA stimulation. Interestingly, the rise of PU.1 binding activity as well as of PU.1 levels after ATRA treatment was significantly higher in APL patients exhibiting monocytic maturation, as compared to those that did not undergo monocytic differentiation. A variable proportion of ATRA-induced APL cells exhibited monocyte-like morphology and immunophenotype: the proportion of monocytic cells was consistently increased by combined treatment with ATRA and diverse hematopoietic growth factors cocktails, which always comprised M-CSF. Monocytic cells originating from in vitro ATRA-induced maturation of APL cells derive from the leukemic clone as suggested by two lines of evidence: (1) monocytic cells harbor the 15;17 translocation; (2) monocytic cells possess Auer bodies. The c-fms[SUPbright] leukemic blasts preferentially showed the capacity for monocytic differentiation as compared to the c-fms[SUPdim/-] subset: indeed, enforced expression of c-fms into NB4, a PML/RARα[SUB+] cell line, favored the onset of monocytic maturation. Finally, low c-fms expression was observed in an APL relapsing patient resistant to ATRA, as well as in an APL case with t(11;17), PLZF/RARα[SUP+]. These observations indicate that PML/RARα[SUP+] APL blasts are bipotent for differentiation through both neutrophilic and monocytic lineages, whereby... [ABSTRACT FROM AUTHOR]

Lymph node or bone marrow biopsy from sixty-one patients affected by aggressive non-Hodgkin lymphomas (NHL) were retrospectively evaluated to assess the histology at relapse. Eighteen cases (29.5%) were proven to have relapsed or persistent low-grade lymphoma after conventional therapy. In 5/18 patients association of low and high-grade lymphoma was detectable at diagnosis by bone marrow biopsy. In the remaining 13/18 no evidence of follicular lymphoma was detected at diagnosis. The outcome of these patients was compared to that of 43 patients relapsed without change in histology and treated by a second line therapy. Of these 43 patients, 13 were not responders (NR), 10 achieved a partial remission (PR) and 18 complete remission (CR). Two were lost during follow-up. The 18 patients with residual/relapsed indolent subtype received oral cyclophosphamide (100mg/day for 15 days every month for six months): 3 of them had NR, 5 CR, and 10 PR. The overall survival (OS) median time was 39 months in low-grade resistant/relapsed patients and 20 months in patients with aggressive histology. OS at 24 months was 71 and 41%, respectively, (p < 0.02). Most of the patients with high-grade disease were refractory or relapsed after a median of five months, whereas cases with low-grade NHL showed a long lasting stable PR. We suggest that the higher grade patients with residual or relapsed low grade lymphoma were, in fact, transformed low-grade at diagnosis and, after removing the more aggressive component by chemotherapy, it is possible to manage these patients by conventional therapy for indolent lymphomas. [ABSTRACT FROM AUTHOR]

MicroRNAs (miRNAs) are small non-coding RNAs involved in the regulation of critical cell processes such as apoptosis, cell proliferation and differentiation. A small set of miRNAs is differentially expressed in hematopoietic cells and seemingly has an important role in granulopoiesis and lineage differentiation. In this study, we analysed, using a quantitative real-time PCR approach, the expression of 12 granulocytic differentiation signature miRNAs in a cohort of acute promyelocytic leukemia (APL) patients. We found nine miRNAs overexpressed and three miRNAs (miR-107, -342 and let-7c) downregulated in APL blasts as compared with normal promyelocytes differentiated in vitro from CD34+ progenitors. Patients successfully treated with all-trans-retinoic acid (ATRA) and chemotherapy showed downregulation of miR-181b and upregulation of miR-15b, -16, -107, -223, -342 and let-7c. We further investigated whether the APL-associated oncogene, promyelocytic leukemia gene (PML)/retinoic acid receptor α (RARα), might be involved in the transcriptional repression of miR-107, -342 and let-7c. We found that PML/RARα binds the regulatory sequences of the intragenic miR-342 and let-7c. In addition, we observed, in response to ATRA, the release of PML/RARα paralleled by their transcriptional activation, together with their host genes, EVL and C21orf34α. In conclusion, we show that a small subset of miRNAs is differentially expressed in APL and modulated by ATRA-based treatment. [ABSTRACT FROM AUTHOR]

A letter to the editor is presented about Δn-p73 protein as the transcriptional target of promyelocytic leukemia or retinoic acid receptor fusion protein in myeloid differentiation.

Abstract: The infectious complications are an important cause of morbidity and mortality in hematopoietic stem cell transplant (HSCT) recipients. Our retrospective study has the objective to evaluate the incidence, clinical and bacteriologic features of documented infections in these patients. The frequency of infectious complications was analysed in 42 patients with hematologic malignancies who received HSCT from January to December 2002 at Pisa General Hospital. Thirty-three patients underwent autologous HSCT and 9 received allogeneic HSCT. All patients reiceved acyclovir, fluconazole and floroquinolones as prophylaptic regimen. A total of 38 infectious episodes were recognized in 22 patients during the early post-HSCT period (N =27) and in the late post-HSCT period (N =11). Infectious complications rate correlated positively with the deepness and length of neutropenia in the early period. There were 21 episodes of sepsis (the majority by coagulase negative staphylococci), 2 pneumonias and 1 vertebral osteomyelitis. All staphyloccus strains were, in vitro, resistant to oxacillin and ciprofloxacin and 8 out of 15 Gram negative rods were resistant to ciprofloxacin. Most of the infectious complications were cured with appropriated antimicrobial therapy and/or with engraftment and, in 4 cases, with central catheter removal. One patient developed a positive CMV antigenemia; a pre-core mutant form of HBV reactivation was diagnosed in another patient. No cases of invasive fungal infections were recognised. Five patients died but only one from infection (septic shock). Pneumonia was a coexisting cause of death in 2 patient in the late period. We can conclude that most of infectious complications, that occurred in the early period post-HSCT were due to coagulase negative staphylococci and Gram negative rods resistant to ciprofloxacin. For this reason, the usefulness of fluoroquinolone prophylaxis in HSCT recipients should be revaluated. [Copyright &y& Elsevier]

Background: Retinoids, which are derivatives of vitamin A, induce differentiation of acute promyelocytic leukemia (APL) cells in vitro and in patients. However, APL cells develop resistance to retinoic acid treatment. Arsenic trioxide (As2O3) can induce clinical remission in patients with APL, including those who have relapsed after retinoic acid treatment, by inducing apoptosis (programmed cell death) of the leukemia cells. In this study, we investigated the molecular mechanisms by which As2O3 induces apoptosis in retinoic acid-sensitive NB4 APL cells, in retinoic acid-resistant derivatives of these cells, and in fresh leukemia cells from patients.Methods: Apoptosis was assessed by means of DNA fragmentation analyses, TUNEL assays (i.e., deoxyuridine triphosphate labeling of DNA nicks with terminal deoxynucleotidyl transferase), and flow cytometry. Expression of the PML/RAR alpha fusion protein in leukemia cells was assessed by means of western blotting, ligand binding, and immunohistochemistry. Northern blotting and ribonuclease protection assays were used to evaluate changes in gene expression in response to retinoic acid and As2O3 treatment.Results and Conclusions: As2O3 induces apoptosis without differentiation in retinoic acid-sensitive and retinoic acid-resistant APL cells at concentrations that are achievable in patients. As2O3 induces loss of the PML/RAR alpha fusion protein in NB4 cells, in retinoic-acid resistant cells derived from them, in fresh APL cells from patients, and in non-APL cells transfected to express this protein. As2O3 and retinoic acid induce different patterns of gene regulation, and they inhibit the phenotypes induced by each other. Understanding the molecular basis of these differences in the effects of As2O3 and retinoic acid may guide the clinical use of arsenic compounds and provide insights into the management of leukemias that do not respond to retinoic acid. [ABSTRACT FROM AUTHOR]