Search

During the phase of proliferation needed for hematopoietic reconstitution following transplantation, hematopoietic stem/progenitor cells (HSPC) must express genes involved in stem cell self-renewal. We investigated the expression of genes relevant for self-renewal and expansion of HSPC (operationally defined as CD34+ cells) in steady state and after transplantation. Specifically, we evaluated the expression of ninety-one genes that were analyzed by real-time PCR in CD34+ cells isolated from (i) 12 samples from umbilical cord blood (UCB), (ii) 15 samples from bone marrow healthy donors, (iii) 13 samples from bone marrow after umbilical cord blood transplant (UCBT), and (iv) 29 samples from patients after transplantation with adult hematopoietic cells. The results show that transplanted CD34+ cells from adult cells acquire an asset very different from transplanted CD34+ cells from cord blood. Multivariate machine learning analysis (MMLA) showed that four specific gene signatures can be obtained by comparing the four types of CD34+ cells. In several, but not all cases, transplanted HSPC from UCB overexpress reprogramming genes. However, these remarkable changes do not alter the commitment to hematopoietic lineage. Overall, these results reveal undisclosed aspects of transplantation biology.

In most of the acute myeloid leukemia patients there is an aberrant tyrosine kinase activity. The prototype of Sprouty proteins was originally identified in Drosophila melanogaster as antagonists of Breathless, the mammalian ortholog of fibroblast growth factor receptor. Usually, SPRY family members are inhibitors of RAS signaling induced by tyrosine kinases receptors and they are implicated in negative feedback processes regulating several intracellular pathways. The present study aims to investigate the role of a member of the Sprouty family, Sprouty1, as a regulator of cell proliferation and growth in patients affected by acute myeloid leukemia. Sprouty1 mRNA and protein were both significantly down-regulated in acute myeloid leukemia cells compared to the normal counterpart, but they were restored when remission is achieved after chemotherapy. Ectopic expression of Sprouty1 revealed that it plays a key role in the proliferation and apoptotic defect that represent a landmark of the leukemic cells. Our study identified Sprouty1 as negative regulator involved in the aberrant signals of adult acute myeloid leukemia. Furthermore, we found a correlation between Sprouty1 and FoxO3a delocalization in acute myeloid leukemia (AML) patients at diagnosis, suggesting a multistep regulation of RAS signaling in human cancers.

// Valentina Rosso 1 , Jessica Petiti 1 , Enrico Bracco 2 , Roberto Pedrola 1 , Francesca Carnuccio 1 , Elisabetta Signorino 1 , Sonia Carturan 1 , Chiara Calabrese 1 , Giada Bot-Sartor 1 , Michela Ronconi 1 , Anna Serra 1 , Giuseppe Saglio 1 , Francesco Frassoni 3 , Daniela Cilloni 1 1 Department of Clinical and Biological Sciences, University of Turin, Turin, Italy 2 Department of Oncology, University of Turin, Turin, Italy 3 Department of Pediatric Hemato-Oncology and Stem Cell, Cellular Therapy Laboratory, Institute G. Gaslini, Genova, Italy Correspondence to: Daniela Cilloni, email: daniela.cilloni@unito.it Keywords: CALR, PNA, MPN, PCR clamping, diagnostic assay Received: September 14, 2016 Accepted: December 15, 2016 Published: December 23, 2016 ABSTRACT The myeloproliferative neoplasms are chronic myeloid cancers divided in Philadelphia positive (Ph+), chronic myeloid leukemia, or negative: polycythemia vera (PV) essential thrombocythemia (ET), and primary myelofibrosis (PMF). Most Ph negative cases have an activating JAK2 or MPL mutation. Recently, somatic mutations in the calreticulin gene ( CALR ) were detected in 56–88% of JAK2/MPL -negative patients affected by ET or PMF. The most frequent mutations in CARL gene are type-1 and 2. Currently, CALR mutations are evaluated by sanger sequencing. The evaluation of CARL mutations increases the diagnostic accuracy in patients without other molecular markers and could represent a new therapeutic target for molecular drugs. We developed a novel detection assay in order to identify type-1 and 2 CALR mutations by PNA directed PCR clamping. Seventy-five patients affected by myeloproliferative neoplasms and seven controls were examined by direct DNA sequencing and by PNA directed PCR clamping. The assay resulted to be more sensitive, specific and cheaper than sanger sequencing and it could be applied even in laboratory not equipped for more sophisticated analysis. Interestingly, we report here a case carrying both type 1 and type2 mutations in CALR gene.

The Wilms tumor gene WT1 is a useful marker of clonal hematopoiesis and it has been shown to be a good marker of residual disease and it reflects the response to therapy. Although myelofibrosis is characterized by mutations of JAK2 and calreticulin (CALR), these mutations are not useful to monitor response to therapy. In this study we demonstrated that in patients affected by myelofibrosis WT1 correlates with the International Prognostic Scoring System (IPSS) score at diagnosis. Furthermore WT1 is a good marker of response to JAK2 inhibitors especially for patients without blasts and for patients who develop anemia or thrombocytopenia not for progression but as therapy related toxicity. Finally, WT1 transcript reduction can mirror a benefit of therapy on the disease burden. This study demonstrated that WT1 is a good marker for monitoring the response to therapy in patients affected by myelofibrosis.

Meningioma 1 (MN1) gene overexpression has been reported in acute myeloid leukaemia (AML) patients and identified as a negative prognostic factor. In order to characterize patients presenting gene overexpression and to verify if MN1 transcript could be a useful marker for minimal residual disease detection, MN1 was quantified in 136 AML patients with different cytogenetic risk and in 50 normal controls. In 20 patients bearing a fusion gene transcript suitable for minimal residual disease quantitative assessment and in 8 patients with NPM1 mutation, we performed a simultaneous analysis of MN1 and the fusion-gene transcript or NPM1 mutation during follow-up. Sequential MN1 and WT1 analysis was also performed in 13 AML patients lacking other molecular markers. The data obtained show that normal cells consistently express low levels of MN1 transcript. In contrast, high levels of MN1 expression are present in 47% of patients with normal karyotype and in all cases with inv(16). MN1 levels during follow-up were found to follow the pattern of other molecular markers (fusion gene transcripts, NPM1 and WT1). Increased MN1 expression in the BM during follow up was always found to be predictive of an impending hematological relapse.

Transferrin receptor 2 (TFR2) is a transmembrane protein that is mutated in hemochromatosis type 3. The TFR2 gene is transcribed in 2 main isoforms: the full-length (α) and a shorter form (β). α-Tfr2 is the sensor of diferric transferrin, implicated in the modulation of hepcidin, the main regulator of iron homeostasis. The function of the putative β-Tfr2 protein is unknown. We have developed a new mouse model (KI) lacking β-Tfr2 compared with Tfr2 knockout mice (KO). Adult Tfr2 KO mice show liver iron overload and inadequate hepcidin levels relative to body iron stores, even though they increase Bmp6 production. KI mice have normal transferrin saturation, liver iron concentration, hepcidin and Bmp6 levels but show a transient anemia at young age and severe spleen iron accumulation in adult animals. Fpn1 is strikingly decreased in the spleen of these animals. These findings and the expression of β-Tfr2 in wild-type mice spleen suggest a role for β-Tfr2 in Fpn1 transcriptional control. Selective inactivation of liver α-Tfr2 in KI mice (LCKO-KI) returned the phenotype to liver iron overload. Our results strengthen the function of hepatic α-Tfr2 in hepcidin activation, suggest a role for extrahepatic Tfr2 and indicate that β-Tfr2 may specifically control spleen iron efflux.

Components of the renin-angiotensin system and endothelial nitric oxide synthase may co-operate in spiral artery remodelling during placentation, and thus reduce the uteroplacental resistance typical of normal pregnancy. Since lack of such remodelling and abnormal placentation are specific features of pre-eclampsia, it has been suggested that abnormal function of both components of the renin-angiotensin system and endothelial nitric oxide synthase may be involved in its pathogenesis. However, previous studies of the association between pre-eclampsia and polymorphisms of single genes encoding renin-angiotensin system components and endothelial nitric oxide synthase have yielded conflicting results. The aim of this study was to assess if interactions among different polymorphisms of the renin-angiotensin system and nitric oxide synthase are involved in the pathogenesis of pre-eclampsia.Some 359 pregnant women were enrolled: 103 normotensive, 50 with chronic hypertension, 86 with gestational hypertension, and 120 with pre-eclampsia. DNA analysis was performed to evaluate angiotensin-converting enzyme I/D, angiotensin-II receptor 1 1166A/C, angiotensinogen M235T and endothelial constitutive nitric oxide synthase 4b/a polymorphisms. Odds ratios (OR) with 95% confidence interval (CI) and chi2 tests were calculated.The frequency of single gene polymorphisms was similar in each group. The frequency of pairs including the DD genotype of the angiotensin-converting enzyme I/D polymorphism plus other homozygous genotypes was significantly higher in pre-eclamptic patients than in controls (OR=3.04, 95% CI=1.16-7.93).Synergism of angiotensin-converting enzyme I/D and other polymorphisms of renin-angiotensin system components and nitric oxide synthase may be a risk factor for pre-eclampsia.

To the Editor: Many anti‐cancer vaccination strategies have been tested in mice and humans in the attempt to eradicate leukemia cells 1. The vast majority of clinical trials are based on peptide vaccination which allows the induction of cellular response to specific tumor associated antigens 2. WT1(Wilms tumor‐1) gene is located on chromosome 11p13 and encodes a zinc finger transcription factor that plays an important role in cell growth and differentiation. WT1 was originally described as a tumor suppressor gene although many evidences demonstrated that it plays an oncogenic function in the setting of leukemia. WT1 protein represents an optimal tumor antigen since it is highly expressed in acute leukemias, myelodysplastic syndromes (MDS) and myeloproliferative neoplasms 3. By contrast, it is expressed at very low levels in normal hematopoietic progenitors. Expression of the WT1 protein is restricted to a limited set of tissues, including the gonads, uterus, kidney, and spleen.

Mutations of the BCR-ABL1 fusion gene represent a well established cause of resistance to tyrosine kinase inhibitors. Among the different mutations identified T315I is of particular concern since it is not effectively targeted by the majority of Tyrosine Kinase Inhibitors so far available. We developed a novel assay based on peptide nucleic acid (PNA) technology coupled to immunofluorescence microscopy (PNA-FISH) for the specific detection at a single cell level of BCR-ABL T315I mutation thus improving both, diagnostic resolution and the study of clonal prevalence. Furthermore we developed an additional method based on PNA directed PCR-clamping for the fast and easy detection of the mutation. The PNA directed PCR clamping allows to detect an amount of mutated template as low as 0.5 %. This method is highly sensitive, specific and cheap and could be applied even in laboratory not equipped for more sophisticated analysis. Furthermore, the PNA FISH method allows to identify a small amount of progenitor cells still present after therapy with specific inhibitors. We present here two different methods based on PNA for the detection of T315I useful for different purposes. PNA-FISH can be used to study clonal evolution. In addition, this method could help in the study of compound mutations being able to identify two different mutations in a single cell. PNA directed PCR clamping although not superior to sequencing can be applied worldwide even in laboratory not equipped to search for mutations.

BACKGROUND The objective of this study was to evaluate the ability of the clinically available histone deacetylase (HDAC) inhibitor valproate to enhance the cytotoxicity of the Bcr-Abl inhibitor imatinib in imatinib-resistant cell lines. METHODS Interactions between imatinib, and valproate have been examined in imatinib-sensitive and -resistant chronic myeloid leukemia (CML)cell lines (K562, KCL-22, CML-T1) and in bone marrow mononuclear cells (MNCs) derived from imatinib-resistant CML patients. RESULTS In imatinib-sensitive cell lines, cotreatment with imatinib 0.5 μM and valproate 5 μM for 48 hours potently enhanced imatinib-induced growth arrest and apoptosis. In resistant cell lines and in primary MNCs derived from imatinib-resistant patients, valproate restored sensitivity to the cytotoxic effects of imatinib. Coexposure of cells to valproate and imatinib was associated with repression of several genes involved in Bcr-Abl transformation. In particular, the combination valproate–imatinib downregulated the expression of Bcr-Abl and the antiapoptotic protein Bcl-2, which is particularly overexpressed in imatinib-resistant clones. CONCLUSIONS Data from this study suggested that administration of the clinically available HDAC inhibitor valproate may be a powerful strategy to enhance cytotoxic effects of imatinib in those patient resistant to imatinib or in which complete cytogenetic remission has been not reached. Cancer 2006. © 2006 American Cancer Society.

Imatinib represents at present the most attractive therapy for BCR-ABL positive leukemias, even though a percentage of CML patients develop resistance to this compound. For these resistant patients a therapeutic approach based on a combination of drugs is more likely to be effective. In the last years, constitutive NF-kappaB/Rel activity has been demonstrated in several hematological malignancies. As a result, NFkB/Rel-blocking approaches have been proposed as antineoplastic strategies. Furthermore, the identification of specific kinases within the NF-kappaB activation pathway offers a selective target to address tailored therapies. In the current study, we show that the IKK inhibitor PS1145 is able to inhibit the proliferation of CML cell lines and primary BM cells. Moreover, the addition of Imatinib increases the effects of PS1145 in resistant cell lines and BM cells from resistant patients, with a further increase of apoptosis and inhibition of proliferation and colony growth. Our data provide the rational for a new therapeutic approach, which combines Imatinib and the IKK inhibitor PS1145 in CML resistant patients.

BACKGROUND The objective of the current study was to verify the ability to predict response to imatinib therapy using in vitro assays to evaluate the inhibition of Wilms tumor gene (WT1) expression and colony growth after samples obtained from patients with chronic myelogenous leukemia (CML) before the start of treatment were subjected to short-term incubation with imatinib. METHODS WT1 transcript levels and colony growth in bone marrow (BM) samples from 23 patients with CML that was later identified as being responsive to imatinib and from 13 patients with CML that was later identified as not being responsive to imatinib were evaluated after incubation of these samples with imatinib at a concentration of 1 μM for 18 hours. In addition, real-time quantitative polymerase chain reaction (RQ-PCR) analysis of WT1 expression was performed during follow-up, and the results were analyzed for associations with cytogenetic response and with BCR/ABL transcript levels as determined using RQ-PCR analysis. RESULTS Before treatment, it was found that WT1 expression was elevated in BM samples obtained from all patients with CML. WT1 expression and colony growth were reduced significantly after an 18-hour incubation with imatinib in samples obtained from patients who were later identified as responders to treatment, but not in samples obtained from patients who did not experience responses to treatment. Inhibition of WT1 expression in vitro was associated with inhibition of imatinib-induced BCR-ABL tyrosine kinase activity, a finding that also has been made in studies involving certain Philadelphia chromosome (Ph)-positive and Ph-negative cell lines. CONCLUSIONS Inhibition of WT1 transcript levels after a short period of in vitro exposure of pretherapy BM samples to imatinib was correlated with inhibition of colony growth and may represent the basis for an easy test that is capable of predicting the sensitivity of CML to treatment with imatinib for individual patients. Cancer 2004. © 2004 American Cancer Society.

We aimed at investigating in vitro the cytotoxic activity (determined using WST-1, apoptosis and cell cycle assays) of gemcitabine, alone or in combination with mitotane, in mitotane-sensitive H295R and mitotane-insensitive SW-13 cells. Results of these experiments were compared with drug-induced modulation of RRM1 gene, the specific target of gemcitabine. In H295R cells, mitotane and gemcitabine combinations showed antagonistic effects and interfered with the gemcitabine-mediated inhibition of the S phase of the cell cycle. By contrast, in SW-13 cells, except when mitotane was sequentially administered prior to gemcitabine, the combination of the two drugs was synergistic. Such opposite effects were associated with opposite expression profiles of the target gene, with significant up-modulation in H295R but not in SW-13 under gemcitabine and mitotane combination treatment.

Monitoring of acute leukemia patients during and after treatment for the presence of remaining leukemic cells minimal residual disease (MRD) have been shown to give major insight into the effectiveness of treatment. However, so far applicability of this strategy has been limited to those leukaemia subsets characterized by genetic markers amenable to sensitive detection by PCR. Although PCR for immunoglobulin and T-cell receptor gene rearrangement represents the gold standard for MRD detection in most cases of acute lymphoblastic leukemias (ALL) lacking the availability of fusion gene transcripts as molecular markers, the situation in AML is more complicated because, at present, more than 50% of them lack any sort of clonality markers suitable for MRD monitoring. Thus, a number of studies have been performed in the attempt to identify cytogenetic and molecular abnormalities associated with leukemic transformation. The Wilms Tumor Gene (WT1) represents a molecular marker for the detection of the leukemic clone useful for monitoring the presence of leukemic cells in all the patients affected by acute and chronic leukemias as well as myelodysplastic syndromes. The WT1 gene, cloned in 1990 by Call et al. [1] encodes for a protein with the characteristics of a zinc finger transcription factor. WT1 expression is restricted to a small number of tissues [2] including testis, ovaries, myometrium, stromal cells of the uterus, heart, lung, intestine, liver and in the supportive stroma and splenic capsule of the spleen [2]. In contrast, several other tissues and cell lines were negative for WT1 expression. Although the role of the WT1 gene in the development of malignancies in the kidney appears quite well defined, currently its potential function in human hematopoiesis still needs to be clarified. The role of WT1 in the leukemogenesis process appears

Abstract 3732 Background: The BCR-ABL T315I mutation at the gatekeeper residue is frequent in advanced phases of chronic myeloid leukemia (CML) and is one of the main cause of resistance to Tyrosine Kinase Inhibitors (TKI) by disrupting important contact points between the drugs and the enzyme. Although this mutation can be detected by different techniques and at different levels of the mutated clone, the prognostic significance of the absolute amount of the mutated allele is widely unknown. The aim of the study was to develope a novel assay based on peptide nucleic acid (PNA) technology coupled to immuno-fluorescence microscopy (PNA-FISH) for the specific detection at a single cell level of T315I mutation thus improving both the diagnostic resolution and the knowledge on the behaviour of the mutated clone. Methods: We designed a fluorescently-labelled PNA probe, coupled to FISH technology, which allows to distinguish with a high degree of specificity between CD34+ progenitor stem cells harbouring T315I mutation or the wild type form of BCR-ABL. CD34+ cells were enriched from CML patients who were positive for T315I mutation, or from patients who lost T315I mutation after ponatinib treatment. In addition we tested CML patients without T315I mutation as control and BM samples from healthy donors to establish the specificity of the method. CD34+ progenitors cells were enriched by MACS and then cytospun onto slides and hybridized with human species-specific fluorescinated 15 base pairs (bp)-long oligo-PNA, specifically recognizing the BCR-ABL T315I sequence. Slides were analyzed by fluorescence confocal microscopy. Results: We found, with a rather wide variability occurring among patients, a percentage of mutated CD34+ cells ranging from 3 to 90%. In addition these data indicate that fluorescinated BCR-ABL T315I/PNA probe displays a very high specificity towards a single base-pair mismatch. Interestingly, when evaluating the presence of T315I positive cells collected from a patient who lost the mutation (evaluated by sequencing) after ponatinib therapy and acquired T317 mutation a small amount of T315I positive CD34+ cells were still present. This percent did not exceeded 2% of the total CD34+ cell population. Importantly, the lack of positivity detected in CD34 positive cells from CML patient without mutations or in 20 healthy subjects demonstrates a high specificity of this method. Conclusions: BCR/ABL T315I/PNA probe method displays high specificity and reliability in discriminating cell subpopulations harbouring the mutation. In addition, it allows to analyze the CD34+ population at the single cell level and to monitor the behaviour of the clone at the stem/progenitor cell level. This approach allows to monitor longitudinally the evolution of the mutated population over time, the response to specific drugs active against T315I mutants and to characterization the mutated stem/progenitor cell compartment in patients with CML. Disclosures: Saglio: Novartis: Consultancy, Speakers Bureau; BMS: Consultancy, Speakers Bureau; Pfizer: Consultancy.

Abstract 2926 Introduction Angiogenesis plays a central role in the progression of both solid and hematological tumors. In particular, in multiple myeloma (MM) the critical role of bone marrow (BM) microenvironment and angiogenesis has been well documented. The past decade has witnessed a dramatic improvement in the therapeutic options in MM. However, the disease remains incurable, underscoring the need for continued efforts towards understanding MM biology and exploitation of novel therapeutic approaches. In this setting, monoclonal antibodies against myeloma-specific cell surface antigens represent a promising therapeutic approach, which is however hampered by a lack of appropriate target structures expressed across all pathogenic myeloma cells. The Eph receptors, a large family of receptor tyrosine kinases (RTKs) activated by ephrins binding, have been implicated in many processes involved in malignancy, including alteration of the tumor microenvironment and in angiogenesis, in both of which EpHA3 likely plays an active role. Aberrant expression of EpHA3 is seen in many types of hematolologic malignancies (some leukemic cell lines, T-cell lymphoma, acute lymphoblastic leukemia, myeloproliferative neoplasms) although it is not expressed ubiquitously. Finally, the over-expression of Eph is believed to be sufficient to confer tumorigenic potential although probably further mechanisms can occur to abnormally activate the receptor. Basing on the role of EpHA3 in haematological malignancies, a first-in-class engineered IgG1 antibody targeting the EpHA (KB004) was developed and it is now under phase I clinical trials in USA and Australia for the treatment of EpHA3 overexpressing hematological myeloid malignancies refractory to conventional treatment. We investigated the EpHA3 role and its preferential membrane–bound by GPI linker ligand EFNA5, in MM patients in order to define EpHA3 as new molecular target for a novel therapeutic approach with a specific anti EpHA3 monoclonal antibody. The EpHA3 expression has been studied through a comparative proteomic analysis between BM endothelial cells (ECs) of patients with MM (MMECs) or with monoclonal gammopathy of undetermined significance (MGECs), of control subjects (normal ECs) and in MM cell lines. Methods After written informed consent, BM aspirates have been collected from 20 MM and 4 MGUS patients. Normal ECs were derived from 3 BM aspirates of subjects with anemia due to iron or vitamin B12 deficiency. We analyzed the expression levels of EpHA3 in normal ECs, MGECs and MMECs and MM cell lines evaluating the mRNA and protein levels by RT-qPCR and by WB coupled to ImmunoFluorescence analysis. The biological effects of EpHA3 targeting in MMECs have been studied silencing the EpHA3 mRNA in MMECs and testing them at 72h after silencing in series of functinal assays including viability assay by trypan blue exclusion staining and by in vitro angiogenesis assay followed by measurement of mesh areas and vessel length. Moreover, we studied EFNA5 mRNA expression levels in Normal ECs, MGECs and MMECs and in MM cell lines by PCR. Results Our data showed that EpHA3 mRNA levels are progressively increased from ECs to MGECs reaching the highest values in MMECs. Subsequent analysis by WB and immunofluorescence confirmed EpHA3 protein upregulation among the different EC types. The MMECs in which EpHA3 has been silenced revealed a protein level reduction of approximately 60% when compared to the control. We could not detect major viability defects. Furthermore, in vitro angiogenesis inhibition was marginal when compared to the not silenced counterpart. To know whether EpHA3 may impact not only MM angiogenesis but also plasma cells, three MM cell lines were studied for the EpHA3 expression. We found the plasma cell lines gave constant over expression of EpHA3. Finally, the preliminary data regarding EFNA5 mRNA expression level showed it is expressed in either MMECs and MM plasma cell lines. The evaluation of KB004 effect on MMECs in term of apoptosis induction and in vitro tube formation inhibition, as well as the analysis of EpHA3 levels in primary MM plasma cells are in progress. Conclusions From this study we expect to characterize the role of the EpHA3in MM patients and to provide experimental evidences supporting the possibility of using EpHA3 as a new molecular target for MM by proving the in vitro efficacy of a monoclonal antibody to target the angiogenesis of MM. Disclosures: No relevant conflicts of interest to declare.

Abstract 4616 Background: The Sprouty family proteins, including Spred, were originally identified in Drosophila melanogaster as an antagonist of Breathless, the ortholog of Fibroblast Growth Factor Receptor (FGFR) in mammals. These proteins are inducible inhibitors of signalling induced by receptor tyrosine kinases. Their main function is to deregulate the RAS/MAPK and RAS/RAF/ERK signal pathways by physically interacting. The role of Spread proteins in haematological malignancies is still not been clarified. Aim: The aim of this study was to investigate a possible involvement of Spred in maintaining the aberrant TK signalling in patients affected by acute myeloid leukaemia (AML). Methods: Bone marrow (BM) cells were collected from 82 AML patients at diagnosis and 10 BM samples from healthy donors as control. In addition 20 patients were analyzed during follow-up at the time haematological remission. All the patients included had been characterized at the cytogenetic level by conventional karyotyping, and screened by reverse transcriptase-PCR for the presence of the most frequent fusion transcripts or mutations. We analysed Spread mRNA expression by RQ-PCR and the protein by Western blot and immunofluorescence assay. In addition gain of function experiments were performed by transfecting with Spred coding sequence different leukemic cells lines lacking Spred activity. Results: We found that Spread mRNA levels were significantly decreased in AML compared to healthy subjects (2−DDct = 0,1 in AML compared to 0,6 in controls) (p Conclusions: A decreased expression and activity of Spred, a negative regulator of TK activity through Ras pathway, is implicated in sustaining the oncogenetic signalling and abnormal proliferation induced by tyrosine kinase proteins in acute myeloid leukemia patients. Disclosures: No relevant conflicts of interest to declare.

Abstract 3472 Background: The JAK2V617F gene mutation is a common feature of Essential Thrombocythemia (ET), Polycythemia Vera (PV) and Primary Myelofibrosis (PMF); however the disease can occur without the JAK2 mutation suggesting that ET, PV and PMF share a common molecular mechanisms which is still unknown. In addition, in patients with the JAK2V617F mutation a substantial proportion of progenitor cells do not bear the JAK2V617F mutation and it is still unclear whether this population is normal or not. Methods: 64 patients affected by MPNs and 12 healthy subjects were included in the study. Twenty three patients were affected by ET, 25 by PV and 22 by PMF. We analyzed the expression, of the anti-apoptotic gene Bcl-xL, both at mRNA and protein level by qRT-PCR and immunofluorescence assay with specific antibodies. Erythroblasts, CD34+ and CD34+CD38-cell populations were selected and analyzed. Moreover, we designed specific PNA (Peptide Nucleic Acid) for JAK2V617F and for Bcl-xL isoform to identify their presence/expression at single CD34+ cell level. Results: Bcl-xL protein and mRNA were found progressively over-expressed in erythroblasts, in CD34+ and in CD34+ CD38- cells from ET, PV and PMF patients without any differences between JAK2V617F and wild type (WT) patients. The median protein level in erythroblasts increased from 22 Relative Units (RU) in ET, to 68,5 in PV and to 85 in PMF. Similarly, in CD34+ Bcl-xL increased from 30 RU in ET, to 89 RU in PV, and to 135 RU in PMF. Finally, CD34+CD38-increased from 17.4 RU in ET, to 45.5 RU in PV, to 101.7 RU in PMF. In addition, analysis by PNA identified distinct progenitor cells population. In patients bearing the JAK2 mutation, three CD34+ cell sub-populations were found: (a) one JAK2 positive and with high levels of Bcl-xL; (b) one JAK2 negative and with high levels of Bcl-xL. Thus, the cell population showing high levels of Bcl-xL is always greater than the JAK2 positive one; (c) one double negative population. In patients without JAK2 mutation, two CD34+ cell populations are identified: (a) one characterized by high levels of Bcl-xL and (b) one double negative. The distribution of these cell subpopulations is different in the distinct MPN. Conclusions: We have identified a previously undisclosed CD34+ cell population which is characterized by high level of Bcl-xL expression and represents the majority of CD34+ cells both in wild type and mutated samples. Interestingly, in mutated samples, this population encompasses the JAK2 mutated one. These findings suggest that Bcl-xL plays an important role in MPN, although it remains undisclosed whether this activation is dependent from an upstream oncogenetic signal. Finally, with this technique we can now identify a putative residual normal CD34+ cells in MPN which may be useful for monitoring patients undergoing targeted therapy with inhibitors. Altogether, these findings disclose unfolded aspects of pathophysiology of MPN and may contribute to a better understanding of the pathogenesis of MPN. Disclosures: Barosi: Novartis: Membership on an entity's Board of Directors or advisory committees. Saglio:Novartis Pharmaceutical: Consultancy, Speakers Bureau; Bristol-Myers Squibb: Consultancy, Speakers Bureau; Pfizer: Consultancy.

Background Usefulness of iron chelation therapy in myelodysplastic patients is still under debate but many authors suggest its possible role in improving survival of low-risk myelodysplastic patients. Several reports have described an unexpected effect of iron chelators, such as an improvement in hemoglobin levels, in patients affected by myelodysplastic syndromes. Furthermore, the novel chelator deferasirox induces a similar improvement more rapidly. Nuclear factor-κB is a key regulator of many cellular processes and its impaired activity has been described in different myeloid malignancies including myelodysplastic syndromes.Design and Methods We evaluated deferasirox activity on nuclear factor-κB in myelodysplastic syndromes as a possible mechanism involved in hemoglobin improvement during in vivo treatment. Forty peripheral blood samples collected from myelodysplastic syndrome patients were incubated with 50 μM deferasirox for 18h.Results Nuclear factor-κB activity dramatically decreased in samples showing high basal activity as well as in cell lines, whereas no similar behavior was observed with other iron chelators despite a similar reduction in reactive oxygen species levels. Additionally, ferric hydroxyquinoline incubation did not decrease deferasirox activity in K562 cells suggesting the mechanism of action of the drug is independent from cell iron deprivation by chelation. Finally, incubation with both etoposide and deferasirox induced an increase in K562 apoptotic rate.Conclusions Nuclear factor-κB inhibition by deferasirox is not seen from other chelators and is iron and reactive oxygen species scavenging independent. This could explain the hemoglobin improvement after in vivo treatment, such that our hypothesis needs to be validated in further prospective studies.

Core-binding factor (CBF) leukemias are characterized by a high degree of sensitivity to high-dose cytarabine (ARA-C) treatment and by a relatively favorable prognosis compared with most other forms of adult acute myeloid leukemia (AML). The molecular basis of the response to chemotherapy is still being analyzed. The proteinase 3 (PR3) gene codes for a serine protease with a broad spectrum of proteolytic activity. PR3 is involved in the control of proliferation of myeloid leukemia cells, and when it is abnormally expressed, it confers factor-independent growth to hematopoietic cells. In this study, we analyzed the expression levels of PR3 in 113 AML patients. PR3 is highly expressed in AML, mainly in CBF leukemias in which PR3 is not only expressed, but also abnormally localized within the nuclear compartment. Nuclear PR3 results in cleavage of nuclear factor (NF)-kappaB p65 into an inactive p56 subunit lacking any transcriptional activity. The nuclear localization of PR3 is responsible for increased proliferation, apoptosis arrest and increased sensitivity to high-dose ARA-C. This study provides a new molecular mechanism that is responsible for NF-kappaB inactivation and increased sensitivity to chemotherapy in CBF leukemias.Leukemia advance online publication, 14 January 2010; doi:10.1038/leu.2009.207.

Abstract 3964 Poster Board III-900 Despite the role of Bcr-Abl in the pathogenesis of Chronic Myeloid Leukemia (CML) is well established, the mechanisms leading to CML progression remain unknown. By using our model of Drosophila melanogaster (Dm) transgenic for human Bcr-Abl we have identified Dab1 and Dab2 as genes involved in CML progression. In Dm the loss of function of these genes induced a worsening of the phenotype generated by hBcr-Abl expression. Moreover, an even stronger phenotype was obtained by silencing Disabled using RNAi fly strains. By contrast, Dab gain of function rescued Bcr-Abl phenotype. Disabled is a non receptor tyrosine kinase, identified in Dm as an adaptor protein acting downstream of many tyrosine kinases receptors (RTK). One of the human homolog of Disabled, Dab1 is a large common fragile site gene, involved in neural migration and the other homolog Dab2 codes is an adaptor protein implicated in RTK signalling, endocytosis, cell adhesion and differentiation. The downregulation of both genes is described in many types of cancer suggesting their possible role in oncogenesis but their involvement in haematological malignancies has never been described. The aim of the study was to investigate the role of Dab1/2 in CML progression. Dab1 and Dab2 mRNA was analyzed by Real Time PCR in 94 samples from 82 CML patients (34 PB and 60 BM). Among those patients 55 were collected at diagnosis (19 enrolled in TOPS study), 9 patients in CP collected at the time of imatinib resistance, 7 in accelerated phase and 11 in BC, In addition 21 healthy donors (10 PB and 11 BM). In 18 patients, genes expression was analyzed during remission as well. Protein expression was investigated by Western Blot and Immunofluorescence. In addition, K562 cells were transfected with Dab plasmids to gain insight about the effects of Dab1/2 on cell proliferation and apoptosis. We found that in CML patients Dab1/2 expression levels were significantly decreased in either BM or PB (p Disclosures: No relevant conflicts of interest to declare.

Abstract 3470 Poster Board III-358 The role of Bcr-Abl in the pathogenesis of Chronic Myeloid Leukemia (CML) is well established, however, the mechanisms leading to CML progression remain poorly understood. By using our model of transgenic Drosophila Melanogaster (Dm) for human Bcr-Abl driven CML we have identified Rab5 as a gene involved in the regulation of CML progression. The Rab5 is a member of gene family small GTPases which are involved in the regulation of vesicular transport. Lately several important reports have linked some members of the Rab family to invesivness and migration of cancer cells. Rab5 is associate with alpha-integrin subunits and modulates their endosomal traffic and subcellular localization. We have observed that a loss of function of Rab5 gene have induced a worsening of the CML phenotype generated by hBcr-Abl expression. In contrast, Rab gain of function rescued Bcr-Abl phenotype. The aim of the study was to evaluate the expression of Rab5 in CML cells to better understand if a potential correlation with progression, which has been observed in the model, could be confirmed in patients. Methods Rab5 gene expression was measured by Real Time PCR in 90 samples from 80 CML patients (32 PB and 58 BM). Among those, 53 are collected at diagnosis (19 of 53 patients have been enrolled in TOPS study). In addition, 9 samples from in CP patients have been collected at the time of imatinib resistance, 7 in accelerated phase and 11 in BC. In 14 patients, genes expression was analyzed during remission as, well. In parallel, 21 healthy donors (10 PB and 11 BM) have been evaluated. Rab5 protein expression was investigated by Western Blot and Immunofluorescence. We have also utilized K562 transfected with Rab5 plasmid, which we have generated to gain insight about the effects of Rab5 on cell proliferation and apoptosis. Results Rab5 transfection and overexpression in K562 significantly reduced proliferation and affected apoptosis. We found that in CML patients Rab5 expression levels were significantly decreased in either BM or PB (p Disclosures No relevant conflicts of interest to declare.

The Wilms' tumor gene WT1 is a reliable marker for minimal residual disease assessment in acute leukemia patients. The study was designed to demonstrate the potential use of WT1 to establish quality of remission in acute leukemia patients for early identification of patients at high risk of relapse. A prospective study based on a quantitative Real-Time PCR (TaqMan) assay in 562 peripheral blood samples collected from 82 acute leukemia patients at diagnosis and during follow-up was established. The evaluation of WT1 in peripheral blood samples after induction chemotherapy can distinguish the continuous complete remission patients from those who obtain only an "apparent" complete remission and who could relapse within a few months. WT1 helps identify patients at high risk of relapse soon after induction chemotherapy allowing post-induction therapy in high risk patients to be intensified.

Mutations in nucleophosmin (NPM) exon 12 and the resulting delocalization of NPM into the cytoplasm are the most specific and frequent cellular events in acute myeloid leukemia patients (AML) with normal karyotype. Cytoplasmatic NPM (NPMc+) is associated with responsiveness to chemotherapy and better prognosis. The activation of nuclear factor-kappaB (NF-kappaB) has been demonstrated to occur in a subset of AML patients and is thought to induce resistance to many chemotherapeutical agents. In this study, we demonstrate the increased in vitro sensitivity of NPMc+ cells to chemotherapeutical agents and their reduced NF-kappaB activity. Furthermore, we provide evidence of the interaction between NPMc+ and NF-kappaB in the cytoplasm, resulting in the sequestration and inactivation of NF-kappaB. The cytosolic localization and consequent inactivation of NF-kappaB justifies the reduced NF-kappaB DNA-binding activity observed in NPMc+ patients. These data, taken together, may provide a possible explanation for the increased rate of chemosensitivity observed among the NPMc+ patients.

Background: Philadelphia positive (Ph+) disorders, such as Chronic Myelogenous Leukemia (CML) are characterized by the presence of abnormal chromosome rising from translocation between chromosome 9 and 22 thus giving birth to a chimeric oncogenic protein named Bcr-Abl. This oncogenic kinase displays constitutive tyrosine kinase activity which leads to tyrosine residues autophosphorylation, in turn recruiting SH2 and/or PTB containing proteins. In the last decade Bcr-Abl targeted therapy has been successfully employed and, among currently available drugs inhibiting Bcr-Abl activity, Imatinb mesylate represents the most efficient. Despite the huge amount of data reporting the effects of Imatinib on signal transduction pathways (for example ERK1/2 and PI3K activation, CrkL phosphorylation etc…) in Ph+ leukemic cells rather few experimental evidences are available on the effects of Imatinib on adapter molecules. Therefore we are currently attempting to investigate such field. Aims and Methods: The significance of interactions occurring between Bcr-Abl and adapter molecules is still matter of debate. Most of the interactions so far described (CrkL, Grb2, PI3K p85 regulatory subunit etc…) appear to play a role in coordinating and integrating a plethora of signals which in turn lead to proliferation, cell survival and/ or cytoskeletal organization. In the last years few, but very interestingly, data supporting the hypothesis that adapter molecules might also act as c-Abl catalytic regulators have been presented. By means of an interactomic approach, based on proteomic strategy using GST-Pull Down assay with an array of SH2 containing proteins, we attempted to gain insight into the role played by adapter molecules and Bcr-Abl interactions. Results and Conclusions: The data herein presented aims to demonstrate the presence of quaternary complex involving the SH2-SH3 containing adapter protein Nck-beta, the oncogenic tyrosine kinase Bcr-Abl and the RNA binding protein Sam68. The experimental evidences we have collected support the hypothesis of an Imatinib-dependent interaction occurring between Nck-beta and Bcr-Abl. Furthermore, Pull Down experiments indicate an intermolecular interaction between Nck-beta and Sam68, supporting the idea of a novel complex Bcr-Abl/Nck-beta/Sam68. Interestingly, preliminary data carried-out using RNA Pull Down assay suggest that the quaternary complex Nck-beta/Sam68/ Bcr-Abl might modulates splicing process of a gene encoding for a protein capable of regulating apoptosis events, such as Bcl-X. Taken together these results represent the first experimental evidences showing an interaction between the oncogene Bcr-Abl and Sam- 68 leading to speculate a novel putative role played by Bcr-Abl in the intriguing and complex mRNA splicing scenario.

CD7/CD56-positive acute myeloid leukemias are characterized by constitutive phosphorylation of the NF-kB subunit p65 at Ser536

Recent advances in molecular genetics have increased knowledge regarding the mechanisms leading to myelodysplastic syndrome (MDS), secondary acute myeloid leukemia (AML), and therapy-induced MDS. Many genetic defects underlying MDS and AML have been identified thereby allowing the development of new molecular-targeted therapies. Several new classes of drugs have shown promise in early clinical trials and may probably alter the standard of care of these patients in the near future. Among these new drugs are farnesyltransferase inhibitors and receptor tyrosine kinase inhibitors including FLT3 and VEGF inhibitors. These agents have been tested in patients with solid tumors and hematologic malignancies such as AML and MDS. Most of the studies in MDS are still in early stages of development. The DNA hypomethylating compounds azacytidine and decitabine may reduce hypermethylation and induce re-expression of key tumor suppressor genes in MDS. Biochemical compounds with histone deacetylase inhibitory activity, such as valproic acid (VPA), have been tested as antineoplastic agents. Finally, new vaccination strategies are developing in MDS patients based on the identification of MDS-associated antigens. Future therapies will attempt to resolve cytopenias in MDS, eliminate malignant clones, and allow differentiation by attacking specific mechanisms of the disease.

Idiopathic hypereosinophilic syndromes (HES) comprise a spectrum of indolent to aggressive diseases characterized by persistent hypereosinophilia. Hypereosinophilia can result from the presence of a defect in the hematopoietic stem cell giving rise to eosinophilia, it can be present in many myeloproliferative disorders or alternatively it may be a reactive form, secondary to many clinical conditions. The hybrid gene FIP1L1-PDGRFalpha was identified in a subset of patients presenting with HES or chronic eosinophilic leukemia (CEL). In spite of this, the majority of HES patients do not present detectable molecular lesions and for many of them the diagnosis is based on exclusion criteria and sometimes it remains doubt. In this study we explored the possibility to distinguish between HES/CEL and reactive hypereosinophilia based on WT1 transcript amount. For this purpose, 312 patients with hypereosinophilia were characterized at the molecular and cytogenetic level and analyzed for WT1 expression at diagnosis and during follow-up. This study clearly demonstrates that WT1 quantitative assessment allows to discriminate between HES/CEL and reactive eosinophilia and represents a useful tool for disease monitoring especially in the patients lacking a marker of clonality.

The FoxO family of transcription factors is regulated by PI3K/Akt induced phosphorylation resulting in nuclear exclusion and degradation. Nuclear FoxO transcribes proapoptotic molecules and cell cycle inhibitors. Although multiple mechanisms regulate FoxO activity, Akt seems to be crucial to its regulation and function. PI3K/Akt pathway has been reported to be abnormally activated in AML blast cells. The aim of this study was to investigate the function of FoxO in AML blast cells and the presence of alternative pathways responsible for FoxO3 inactivation other than PI3K-Akt. BM cells were collected from 35 AML patients at diagnosis and after chemotherapy and from 20 healthy donors. The expression levels of FoxO1, FoxO3, FoxO4 were tested by RQ-PCR, FoxO3 protein amount and localization by Western blot and immunofluorescence and the DNA binding activity by EMSA. Furthermore, downstream target genes transcribed by FoxO3 were quantified. Among these, Spred1 which codes for a negative regulator of RTK signal, including Ras mediated pathway triggered by FLT3. We have previously described the absence of Spred1 is AML patients and we have demonstrated that it promotes growth arrest and apoptosis in haematopoietic cells. Finally, BM cells were incubated with 5 mM of the PI3K inhibitor LY294002 and 20 mM PS1145, the inhibitor of IKK kinase also responsible for FoxO phosphorylation and with the combination LY294002 plus PS1145. We found that the amount of FoxO1, FoxO3 and FoxO4 mRNA are similar in AML patients and controls. Interestingly, while FoxO3 in control cells is localized in both, nucleous and cytoplasm, is completely cytoplasmatic in AML cells and it enters the nucleous after chemotherapy. The quantification of FoxO fluorescent signal in controls shows a mean value of intensity of 21.4±2 in the nucleous and 14,6±1.7 in the cytoplasm. By contrast, in AML cells is 8,2±4 in the nucleous and 18.1±4,6 in the cytoplasm. Additionally, FoxO3 DNA binding activity in AML patients is completely absent at diagnosis and reappears after therapy. Also the mRNA of the target gene Spred1 is rather undetectable at diagnosis (mean value 2−ΔΔCt= 0,009±0,3) and is upregulated during remission (mean value 2−ΔΔ= 2±1,5) or after LY29400 incubation (mean value =0,8±0,3). LY294002 and PS1145 results in FoxO partial nuclear relocalization with a nuclear signal of 15±3 and 12±3 respectively. Interestingly, the association of PS1145 and LY294002 induces a complete nuclear shuttle with a nuclear signal of 25±4, suggesting that both pathways are implicated in FoxO inactivation. Taken together these observations suggest that FoxO inactivation may be crucial for the apoptosis arrest observed in AML. These data demonstrate that also IKK pathway contributes to this effect, providing the rationale for a therapeutic strategy based on the combination of selective inhibitors such as FLT3 or Akt inhibitors or standard chemotherapy and the IKK inhibitor.

Homozygous beta-thalassemia patients may develop iron overload even if untransfused, due to inappropriately high intestinal iron absorption. Reduction of hepcidin synthesis has been reported both in patients and in animal models. We have measured liver hepcidin and other iron gene transcripts in two different mouse models of beta-thalassemia at different ages.Mice Hbb(th/th), characterized by spontaneous homozygous deletion of the major b1 globin gene were studied at 2 and 8 months. Mice Hbb(th/3+), characterized by the heterozygous deletion of b1 and b2 globin genes were studied at 4 and 10 months. Hematologic data were obtained and iron overload estimated by Perls' staining of the liver. Expression of liver hepcidin, Tfr2, Hjv, Fpn and Hfe RNA was assessed by real-time polymerase chain reaction. Levels of serum cytokines (interleukin-6, IL-1beta, IL-10, granulocyte-macrophage colony-stimulating factor) levels were assayed by enzyme-linked immunosorbent assay.Hemoglobin, hematocrit and mean corpuscular volume were significantly reduced in both beta-thalassemia models, more significantly in Hbb(th/3+), which have the greater, age-dependent, iron overload. Hepcidin RNA was not increased despite iron overload in both strains. Fpn RNA was increased and Tfr2 was decreased in older animals. Inflammatory cytokine levels were striking variable and unrelated to hepcidin levels.Although anemia is reported to inhibit hepcidin expression, normal hepcidin synthesis was maintained in both thalassemic models studied. However, hepcidin levels were inappropriate for the body iron, especially in Hbb(th/3+) 10-month-old animals. As we previously reported in wild type mice after parenteral iron overload, Tfr2 is reduced and Fpn RNA increased in thalassemic mice. Inflammatory cytokines did not play a major role in increasing hepcidin levels or in modifying iron homeostasis in this study.

NF-kB is a transcription factor that mediates antiapoptotic signals in several cancer cell lines. Here we have demonstrated that the cytotoxic drug, Etoposide, activates NF-kB in K562, a chronic myeloid leukemia blast crisis cell line. Treatment with the NF-kB inhibitors MG-132, Bay11-7082, and Resveratrol impedes Etoposide-induced NF-kB activation, rendering K562 sensitive to Etoposide-induced apoptosis. Stable expression of mutant form of IkB-alpha, which retains NF-kB inactive in the cytoplasm of cells, confirmed the data obtained with molecular inhibitors. Both inhibitors and stable expression of SR-IkB are associated with down-modulation of the antiapoptotic protein Bcl-xL, suggesting that the survival pathway activated by Etoposide involves NF-kB-mediated Bcl-xL expression.

Introduction. Chronic Myeloid Leukemia (CML) is a myeloproliferative disorder caused by the Philadelphia translocation. Rare patients with a clinical presentation of CML are negative for the Ph chromosome. The pathogenesis of Ph negative CML is still unknown. Different reports have demonstrated that the transcription factor NF-kappaB is essential for Bcr-Abl mediated transformation. NF-kappaB is composed of two subunits (mainly p65 and p50) which are retained into the cytoplasm by the inhibitory protein IkappaB-alpha. Different stimuli trigger IkappaB degradation and nuclear translocation of NF-kappaB, where it mediates the transcription of different genes involved in cellular proliferation, transformation and resistance to apoptosis. Aim of the work. We have evaluated the role of NF-kappaB in primary chronic myeloid leukemia samples both positive and negative for the Philadelphia chromosome. Methods. Bone marrow samples of 10 chronic myeloproliferative disorders (6 Ph positive and 4 Ph negative CML), 1 CML blast phase, 2 Acute Myeloid Leukemia and 3 healthy donor have been collected at diagnosis. Each sample has been lysed to obtain cytosolic and nuclear extracts. Western blot have been performed to evaluate the expression of p65 and the regulatory protein IkappaB-alpha. DNA binding activity of NF-kappaB has been measured with an ELISA method (TransAM). To inhibit NF-kB, primary cells have been incubated with 1 microM MG-132, 90 microM Resveratrol and 5 microM Bay11-7082 or have been infected with a lentivirus construct containing dsRNA directed against the p65 subunit of NF-kB and a lentivirus expressing a mutated IKB which retains NF-kB inactive in the cytoplasm. Results. Ph+ and Ph- CML samples express both in the cytosol and in the nucleus higher levels of p65 respect to normal peripheral blood and normal bone marrow samples. In normal samples IkB-alpha is detectable only in the cytosol while in Ph+ and Ph- CML samples it is predominately expressed in the nucleus. DNA binding activity of NF-kappaB is not particularly increased in CML respect to normal bone marrow samples. Only CML blast phase and Acute Myeloid Leukemia show markedly increased DNA binding activity of NF-kappaB. Immunoprecipitates of nuclear and cytosolic IkappaB-alpha have been performed. The pro-apoptotic p53 co-immunoprecipitates with IkappaB-alpha. Treatment with NF-kappaB inhibitors MG-132, Resveratrol and Bay11-7082 disrupts p53-IkBalpha dimer rendering cells susceptible to the apoptotic stimulation induced by Doxorubicine. To confirm these data, primary CML samples have also been infected with a lentivirus construct containing dsRNA directed against p65 and a lentivirus expressing a mutated IKB which retains NF-kB inactive in the cytoplasm. In both cases cells becomes more sensitive to Doxorubicin-induced apoptosis, due to disruption of IkB - p53 dimer. Conclusion. Nuclear and cytosolic IkappaB-alpha mediated p53 sequestration is a common event in both Ph+ and Ph- CML, which may contribute to the pathogenesis of this disorder due to impairment of p53 pro-apoptotic functions. NF-kB inhibition may represent a powerful strategy to render CML cells more susceptible to apotosis.

Background. The renin–angiotensin system (RAS) and nitric oxide synthase (NOS) play a key role in the progression of primary glomerulonephritis (GN). Although previous studies have examined genetic risk associated with single gene variations, experiments assessing risk conferred by multiple gene variations are still scanty. Methods. The effect of combination of variant alleles of four genes encoding for three components of the RAS [angiotensin converting enzyme insertion/ deletion (ACE I/D), angiotensin II receptor 1 (AT1R 1166A/C), angiotensinogen (AGT M235T)] and for NOS (ecNOS4b/a) on the development and progression of membranous GN (MGN) were evaluated in a longitudinal study comparing 117 patients with serum creatinine (s-Cr)

Transforming growth factor beta1 (TGF-beta1) plays an important role in the modulation of cellular growth and differentiation in a wide variety of cell types and in the production/degradation of the extracellular matrix (ECM). We investigated whether G-800A, C-509T and Leu10--Pro polymorphisms in the TGF-beta1 gene could be involved in the development and progression of immunoglobulin A nephropathy (IgAN).DNA samples were obtained from 101 patients with biopsy proven IgA mesangial nephropathy and 118 healthy controls. The genotypes of G-800A, C-509T and Leu10--Pro polymorphisms in the TGF-beta1 gene were determined by polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) with MaeIII, Eco 81I and Pst I, respectively.No significant differences were observed in the genotype distribution of the three TGF-beta1 polymorphisms between patients and controls. The TAC haplotype (T=Leu10, A-800 and C-509 alleles, respectively) was significantly associated with IgAN (p=0.043; odds ratio (OR) =2.334, 95 % confidence interval (95%CI) 1.01-5.41).Our study suggests that the haplotype reconstruction of TGF-beta1 gene polymorphisms could be more informative than the investigation of single nucleotide polymorphisms for defining the associated risk of developing IgAN. Further research is needed on larger cohorts to confirm TGF-beta1 involvement and test other TGF-beta1 variants with possible additive or synergistic effects.

The ID (insertion/deletion) polymorphism of the ACE (angiotensin-converting enzyme) gene controls plasma ACE levels. Both have been correlated with ISR (in-stent restenosis) in preliminary analyses, but not confirmed in larger studies. In the present study, baseline and 6-month quantitative coronary analysis were performed in 897 patients who had stent implantation and the ID polymorphism genotyped. Plasma ACE levels were measured in 848 patients (95 %). Restenosis rates among genotypes were 31.2 % DD, 25.5 % ID and 28.8 % II (not significant). Plasma ACE levels were significantly higher in restenotic patients compared with patients without restenosis (30.7 + 18.6 units/l compared with 22.8 + 12.8 units/l; P = 0.0001) and a strong independent predictor of ISR [OR (odds ratio) = 3.70; 95 % CI (confidence interval), 2.40–5.71; P < 0.0001], except in diabetics. In the subgroup of diabetics and patients with AMI (acute myocardial infarction), the DD genotypes actually had a lower risk of ISR than the II genotypes (diabetics, OR = 0.16; 95 % CI, 0.04–0.69; P = 0.014; and patients with AMI, OR = 0.21; 95 % CI, 0.061–0.749; P = 0.016). After exclusion of diabetics and patients with AMI, ISR rates for genotypes in 632 patients were 31.7 % DD, 24.3 % ID and 17.6 % II (P = 0.02; DD compared with non-DD OR = 1.57; 95 % CI, 1.09–2.25). The association between the D allele and ISR observed in selected populations does not hold with a larger sample size. Other than sample size, clinical variables can modulate the association between ID polymorphism and ISR. Plasma ACE level is a risk factor for ISR, independently of the ID genotype.

Objective— Because of the receptor-mediated antiproliferative effects of estradiol on vascular smooth muscle cells, our study aimed at identifying a role of PvuII and XbaI polymorphisms of the α-estrogen receptor (αER) gene in the occurrence of restenosis after coronary stent implantation (in-stent restenosis [ISR]). Methods and Results— In 858 patients (148 women), 955 lesions were treated with stent implantation, and the PvuII C/T and XbaI G/A polymorphisms of the αER gene were determined. Quantitative angiography was performed before and after stenting and at 6-month follow-up. The allelic frequencies were similar between sexes (C/T allele, 0.43/0.57 and 0.44/0.56; P =0.9; G/A allele, 0.35/0.65 and 0.38/0.62; P =0.8; in women and men, respectively). A significantly higher ISR rate in women than in men homozygous for the T-allele of the PvuII polymorphism (42.6% versus 26.9%, P =0.03) or the G-allele of the XbaI polymorphism (41.2% versus 19.4%, P =0.04) was observed. At multivariate analysis, T/T genotype was the only independent predictor of ISR in women but not in men (odds ratio, 1.5; 95% CI, 1.0 to 2.1; P =0.03). XbaI polymorphism was no longer associated with ISR in both sexes. Conclusions— Women homozygous for the T-allele of the PvuII polymorphism of the αER gene treated with coronary stent implantation have a higher risk of ISR than men.

The usefulness of the WT1 quantitative assessment by real-time quantitative polymerase chain reaction (RQ-PCR) as a marker for minimal residual disease (MRD) detection after allogeneic bone marrow transplantation (BMT) has been reported in a recent issue of Blood by Ogawa et al[1][1] in a series of

Peripheral blood DNA adducts have been considered an acceptable surrogate for target tissues and possibly predictive of cancer risk. A group of 114 workers exposed to traffic pollution and a random sample of 100 residents were drawn from the EPIC cohort in Florence, a population recently shown to present increased DNA adduct levels (Palli et al., Int J Cancer 2000;87:444-51). DNA bulky adducts and 3 DNA repair gene polymorphisms were analyzed in peripheral leukocytes donated at enrollment, by using (32)P-postlabeling and PCR methods, respectively. Adduct levels were significantly higher for traffic workers among never smokers (p = 0.03) and light current smokers (p = 0.003). In both groups, urban residents tended to show higher levels than those living in suburban areas, and a seasonal trend emerged with adduct levels being highest in summer and lowest in winter. Traffic workers with at least 1 variant allele for XPD-Lys751Gln polymorphism had significantly higher levels in comparison to workers with 2 common alleles (p = 0.02). A multivariate analysis (after adjustment for age, season, area of residence, smoking, XPD-Lys751Gln genotype and antioxidant intake) showed a significant 2-fold association between occupational exposure and higher levels of adducts (odds ratio 2.1; 95% confidence interval 1.1-4.2), in agreement with recent pooled estimates of increased lung cancer risk for similar job titles. Our results suggest that traffic workers and the general population in Florence are exposed to high levels of genotoxic agents related to vehicle emissions. Photochemical pollution in warmer months might be responsible for the seasonal trend of genotoxic damage in this Mediterranean urbanized area.

In a recent article in this journal, Klippel et al[1][1] reported that overexpression of the polycythemia rubra vera 1 gene (PRV-1) in purified granulocytes can distinguish patients with polycythemia vera (PV) from those with secondary erythrocytosis (SE) and from healthy subjects. However, as

Acute myeloid leukemia (AML) is characterized by abnormalities frequently affecting transcriptional control elements, leading to differentiation block.[1][1] C/EBPα is one of the most frequently involved transcription factors, being disrupted by point mutations in 7% to 11% of cases.[2][2]-[3][3]

Abstract 2500 Wilms' tumor gene 1 (WT1) is a tumor suppressor gene coding for a zinc finger transcriptional factor which was found overexpressed in acute myeloid leukemias (AML). In AML WT1 functions as an oncogene rather than a tumor suppressor. This may depend on the unbalanced expression of its different isoforms derived from alternative splicing in exon 5 (EX5+/−) or the presence of KTS in exon 9 ( KTS+/KTS-). In normal hematopoietic cells the physiological ratio between KTS+/KTS- isoforms is 1:1. KTS are inserted between the third and fourth zinc fingers thus influencing the DNA binding and therefore the transcriptional activity. The aim of the study was to investigate the possibility of an unbalanced ratio between the isoforms thus leading to the disruption of WT1 function. In addition we correlated KTS+ isoform with clinical and biological features. Methods: we analyzed KTS+/KTS- isoforms in 120 AML patients ( 102 BM samples, 18 PB), 63 chronic phase CML patients (48 BM and 15 PB). In addition we evaluated 5 samples of selected blast cells from AML patients. In a subset of 38 adult acute myeloid leukemia (AML) patients we measured all WT1 isoforms (A[EX5 -/KTS -], B[+/−], C[-/+] and D[+/+]. Quantitative PCR was used for the WT1 isoforms detection and measurement. Results: KTS+ isoform is significantly overexpressed with a ratio KTS+/KTS− 2:1 in both AML and CML patients and it is confirmed in blast cell samples. In the subgroup of patients analyzed for the expression pattern of all WT1 isoforms we detected a significant overexpression of isoform D (EX5+/KTS+) (median value 821) while the isoform A (EX5−/KTS−) is the less represented ( median value 303). In this subgroup the expression of KTS+ isoforms (B+D) is higher than KTS- ( A+C) with a median value of 642 compared to 421. The ratio of WT1 isoforms was not significantly different among FAB subgroups or according to cytogenetic risk, FLT3 (fms-like tyrosine kinase receptor-3) internal tandem duplication or exon 17 mutation, NPM (nucleophosmin) gene mutations and BAALC (brain and acute leukemia, cytoplasmic) gene expression. Conclusion: Although WT1 is overexpressed in AML and CML patients it lacks its typical tumor suppressor function. In this study we have demonstrated the overexpression of WT1 KTS+ isoforms. In addition we have previously demonstrated that KTS+ isoform does not have transcriptional activity since it is mainly localized within the cytoplasm. In conclusion, WT1 is overexpressed in AML but the unbalanced ratio between the isoforms may probably influence the transcriptional activity. Any possible correlation between the unbalanced ratio of WT1 isoforms and clinical outcome requires further prospective studies to be established. Disclosures: No relevant conflicts of interest to declare.

Alternative splicing plays a key role for generating protein diversity and contribute to essential biological processes among them differentiation, cell cycle regulation and apoptosis. Alterations in alternative splicing was identified in several human diseases, including cancer. Bcl-x is a Bcl-2 family member which is alternatively spliced in two distinct transcripts generating two different proteins: Bcl-xL (Long) and Bcl-xS (Short), with antagonistic functions. The long isoform inhibits apoptosis, in contrast the short one activates it. Bcl-xL is highly expressed in different types of cancer. CML is a myeloproliferative disorder characterized by a reciprocal chromosomal translocation t(9;22), that generate Bcr-Abl chimeric protein with constitutive tyrosine kinase activity. Its expression in hematopoietic cells induces uncontrolled and growth factor independent cell proliferation, alteration in cell-cell and cell-matrix adhesion and resistance to apoptosis. It has been reported that in CML Bcl-x isoforms ratio is altered in favor of the anti-apoptotic one (Bcl-xL).We investigated the involvement of Bcr-Abl in regulating splicing events affecting Bcl-x pre-mRNA occurring in CML. By proteomic approach, based on strategy using GST-Pull Down assay, we attempted to gain insight into functional interactions occurring among the oncogenic kinase Bcr-Abl and RNA-binding proteins, identifying physical interactions among the adapter protein Nck-beta, the spliceosome ribonucleoprotein hnRNPA1 and Sam68 which are assembled to form a functional quaternary complex. These interactions were further confirmed by immunofluorescence staining showing co-localization of the proteins within peculiar nuclear splicing regions (nuclear speackles). Using RNA Pull Down assays we detected that the quaternary complex was able to specifically bind BCL-xL mRNA. Using several specific tyrosine kinase inhibitor such as BMS-354825, AMN-107 or STI-571, we identified a key role of BCR-ABL phosphorylation on integrity of the multimeric complex. Furthermore, STI-571 impairs the interaction between quaternary complex and Bcl-xL mRNA. As observed also for other spliced genes like MCL1, PP1γ; PASG, VRK and CENT1. The Bcr-Abl mediated Bcl-x splicing was also confirmed by quantitative PCR and immunofluorescence analysis. Bcr-Abl leads to increased Bcl-xL mRNA expression as proved either by Bcr-Abl ectopic overexpression or by a Bcl-x minigene assay. In conclusion, these data indicate that phosphorilated Bcr-Abl is part of a complex affecting Bcl-x alternative splicing, increasing the anti-apoptotic isoform in respect to the pro-apoptotic one. These data represent the first original report of a direct involvement of Bcr-Abl in splicing events, thus opening new perspectives in CML therapeutic treatment field. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 4771. doi:10.1158/1538-7445.AM2011-4771