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Myeloproliferative neoplasms (MPN) are hematological disorders characterized by increased proliferation of precursor and mature myeloid cells. MPN patients may present driver mutations in JAK2, MPL, and CALR genes, which are essential to describe the molecular mechanisms of MPN pathogenesis. Despite all the new knowledge on MPN pathogenesis, many questions remain to be answered to develop effective therapies to cure MPN or impair its progression to acute myeloid leukemia. The present study examined the expression levels of the Hippo signaling pathway members in patients with polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF), as well as the role that they play in disease pathogenesis. The Hippo pathway is a tumor suppressor pathway that participates in the regulation of cell proliferation, differentiation, and death. Our main findings were: (i) expression of tumor suppressor genes from Hippo pathway were downregulated and seemed to be associated with cell resistance to apoptosis and increased proliferation rate; and (ii) Hippo pathway-related gene expression was associated with mutation status in ET and PMF patients. Therefore, the decreased expression of Hippo pathway-related genes may contribute to the malignant phenotype, apoptosis resistance, and cell proliferation in MPN pathogenesis.

Myeloproliferative neoplasms polycythemia vera (PV), essential thrombocythaemia (ET) and primary myelofibrosis constitute a group of haematological diseases. The comprehensive assessment of signaling pathway activation in blood cells may aid the understanding of MPN pathophysiology. Thus, levels of post-translational protein modifications and total protein expression were determined in MPN patients and control leukocytes by using reverse-phase protein arrays (RPPA). Compared to control samples, p-SRC, p-CTNNB1, c-MYC, MCL-1, p-MDM2, BAX and CCNB1 showed higher expression in PV samples than controls. P-JAK2/JAK2 and pro-apoptotic BIM showed differential expression between JAK2V617F-positive and -negative ET patients. Apoptosis, cancer and PI3K/AKT pathways proteins showed differential expression among the studied groups. For most of the proteins analyzed using Western-Blot and RPPA, RPPA showed higher sensitivity to detect subtle differences. Taken together, our data indicate deregulated protein expression in MPN patients compared to controls. Thus, RPPA may be a useful method for broad proteome analysis in MPN patients´ leukocytes.

Chronic Myeloid Leukemia (CML), Polycythemia Vera (PV), Essential Thrombocythemia (ET) and Primary Myelofibrosis (PMF) are Myeloproliferative Neoplasms (MPN) characterized by clonal myeloproliferation without cell maturation impairment. CML pathogenesis is associated with the Ph chromosome leading to BCR-ABL tyrosine-kinase constitutive expression. The Ph negative MPN (PV, ET and PMF) are characterized by the mutation JAK2(V617F) of the JAK2 protein in the auto-inhibitory JH2 domain, which is found in most PV patients and in approximately half of ET and PMF patients. Considerable effort is being made to understand the role of JAK2(V617F) at the MPN initiation and to clarify the pathogenesis and apoptosis resistance in CML, PV, ET and PMF patients. In the present investigation, we evaluated the Death Inducer-Obliterator (DIDO) (variants DIDO 1, 2 and 3) levels in CML, PV, ET and PMF patients. Our data reported the DIDO 1, 2 and 3 differential expressions in Myeloproliferative Neoplasms.

Cytokines are key immune mediators in physiological and disease processes, whose increased levels have been associated with the physiopathology of hematopoietic malignancies, such as myeloproliferative neoplasms.This study examined the plasma cytokine profiles of patients with essential thrombocythemia, primary myelofibrosis, polycythemia vera and of healthy subjects, and analyzed correlations with JAK2 V617F status and clinical-hematological parameters.The proinflammatory cytokine levels were increased in myeloproliferative neoplasm patients, and the presence of the JAK2 V617F mutation was associated with high IP-10 levels in primary myelofibrosis patients.Essential thrombocythemia, primary myelofibrosis, and polycythemia vera patients exhibited different patterns of cytokine production, as revealed by cytokine network correlations. Together, these findings suggest that augmented cytokine levels are associated with the physiopathology of myeloproliferative neoplasms.

The pathogenesis and clinical outcomes of myeloproliferative neoplasms (MPN) involve genetic and molecular anomalies. The most prevalent somatic mutation in polycythemia vera (PV), essential thromb...

Multiparameter flow cytometry (MFC) is a highly sensitive, fast and specific diagnostic technology with a wide range of applicability in hematology. Although well-established eight-color immunophenotyping panels are already available, most Brazilian clinical laboratories are equipped with four-color flow cytometer facilities. Based on this fact, the Brazilian Group of Flow Cytometry (Grupo Brasileiro de Citometria de Fluxo, GBCFLUX) for standardization of clinical flow cytometry has proposed an antibody panel designed to allow precise diagnosis and characterization of acute leukemia (AL) within resource-restricted areas. Morphological analysis of bone marrow smears, together with the screening panel, is mandatory for the primary identification of AL. The disease-oriented panels proposed here are divided into three levels of recommendations (mandatory, recommendable and optional) in order to provide an accurate final diagnosis, as well as allow some degree of flexibility based on available local resources and patient-specific needs. The proposed panels will be subsequently validated in an inter-laboratory study to evaluate its effectiveness on the diagnosis and classification of AL. © 2014 Clinical Cytometry Society.

MicroRNAs are small non-coding RNAs that inhibit posttranscriptional gene expression through deadenylation and cleavage. Th ese molecules play crucial roles in regulating cell diff erentiation, proliferation and apoptosis [1]. MicroRNA expression levels are strongly associated with numerous human pathogenic diseases [2]. Th us, the discovery of microRNAs has opened up a wide range of possibilities regarding the understanding of disease pathophysiology and the development of new therapeutic agents. Recent studies show that microRNAs may participate in the regulation of apoptosis machinery (apoptomiRs). Apoptosis is a programmed cell death, orchestrated by the BCL-2 protein family, death receptors and inhibitor of apoptosis proteins (IAPs) [3]. Deregulated apoptosis is associated with tumorigenesis and autoimmunity [3] and seems to contribute to myeloproliferative neoplasms (MPNs), which are clonal disorders characterized by myeloaccumulation and in most cases by the presence of a somatic mutation in Janus kinase 2 (JAK2) [4]. Our research group previously described abnormal apoptosis in patients with MPNs [5 – 7]. We found abnormal expression of death-receptor pathway-related genes such as FAIM and C-FLIP in leukocytes and CD34 � hematopoietic stem cells (HSCs) [5], and deregulation of BCL-2 family members associated with JAK2 mutation [6,7]. Th ese fi ndings led us to investigate the molecular mechanisms associated with apoptosis deregulation in patients with MPNs. In this study, we sought to identify microRNAs whose targets are apoptosis-related genes, investigate their expression in patients with MPNs, and correlate this with the expression of apoptosis-related genes and JAK2 mutation allele burden using three algorithms (websites: http://www.diana.pcbi. upenn.edu/cgi-bin/miRGen/v3/Targets.cgi; Microcosm Targets: http://www.ebi.ac.uk/enright-srv/microcosm/cgi-bin/ targets/v5/hit_list.pl?genome_id � 2964; and Target Scan: http://www.targetscan.org). Th e microRNAs and their respective target genes (apoptosis-related genes) predicted by the bioinformatics tools are as follows: miR-15a: BIK and BCL-2; miR-16: BID, BIK, BCL-2 and BCL xl; miR-26a: C-FLIP, CIAP-2 and MCL-1; miR-130b: CIAP-2; miR-21: CIAP-2, FASL and BCL-2; miR-29c: CIAP-1 and MCL-1; and miR-let-7d: A1, BAX, FAS and FASL. In this study, we investigated apoptomiRs miR-26a, -130b, -21, -29c, -let-7d, -15a and -16. We quantifi ed their expression in bone marrow CD34 � HSCs and peripheral blood leukocytes in 27 patients with polycythemia vera (PV), 25 with essential thrombocythemia (ET) and 12 with primary myelofi brosis (PMF) (26 males and 38 females, mean age: 60.5 years). Th e bone marrow control group comprised 14 bone mar

Despite all the knowledge, the cellular and molecular mechanisms involved in myeloproliferative neoplasm (MPN) pathophysiology remain unclear. Authors have shown galectin-1 (Gal-1) and 3 playing roles in tumour angiogenesis and fibrosis, which were correlated with poor prognosis in patients with MPN. In the present study LGALS1 and LGALS3 were differently expressed between polycythemia vera, essential thrombocythemia (ET) and primary myelofibrosis (PMF) diseases. Increased LGALS3 expression was associated with a negative JAK2 V617F status mutation in leucocytes from PMF but not in patients with ET without this mutation. However, a positive Janus kinase 2 (JAK2) V617F cell line established from patients with ET (SET-2 cells) when treated with JAK inhibitor presented high levels of LGALS3. Additionally, high LGALS1 expression was found in CD34(+) cells but not in leucocytes from patients with PMF, in absence of JAK2 V617F mutation, and also in SET-2 cells treated with JAK inhibitor. Thus, our findings indicate that differential expression of LGALS1 and/or LGALS3 in patients with MPN is linked with JAK2 V617F status mutation in these diseases and state of cell differentiation.

Primary myelofibrosis (PM) is a Philadelphia-negative clonal hematopoietic stem cell disorder characterized by intense reactive changes of bone marrow stroma with collagen fibrosis, osteosclerosis and angiogenesis. PM usually affects elderly people, and approximately half of the patients present JAK2V617F mutation. PM clinical course varies from 1 to 30 years, evolving from asymptomatic into progressive bone marrow failure, symptomatic splenomegaly or acute leukemia in 10–20 % of cases. PM risk stratification is based on parameters predicting survival, and several attempts have been made to identify clinical and laboratory features that could predict PM patient survival. This study applied five prognostic scores: Dupriez, Cervantes, Mayo, IPSS and DIPSS-Plus in 62 Brazilians patients from three centers, and compared their relevance and clinical usefulness considering the scores’ parameters, fibrosis, JAK2V617F mutation, splenomegaly, hepatomegaly and treatment. According to the Cervantes, Dupriez and Mayo scores, most patients were stratified into low-risk group. However, when IPSS and DIPSS-Plus were applied, most patients were classified into an intermediate range, being low risk in only 11 and 13 % of patients, respectively. Overall survival at 4 years was 84 %. The Cervantes score was the only one that remained significantly associated with survival in a multivariate analysis. In conclusion, the Cervantes score remains important to the prognostication of PM.

Background Chronic myeloproliferative disorders (MPDs) are clonal haematopoietic stem cell malignancies characterised by an accumulation of mature myeloid cells in bone marrow and peripheral blood. Deregulation of the apoptotic machinery may be associated with MPD physiopathology. Aims To evaluate expression of death receptors9 family members, mononuclear cell apoptosis resistance, and JAK2 allele burden. Subjects and Methods Bone marrow haematopoietic progenitor CD34 cells were separated using the Ficoll-hypaque protocol followed by the Miltenyi CD34 isolation kit, and peripheral blood leukocytes were separated by the Haes-Steril method. Total RNA was extracted by the Trizol method, the High Capacity Kit was used to synthesise cDNA, and real-time PCR was performed using SybrGreen in ABIPrism 7500 equipment. The results of gene expression quantification are given as 2 −ΔΔCt . The JAK2 V617F mutation was detected by real-time allelic discrimination PCR assay. Peripheral blood mononuclear cells (PBMCs) were isolated by the Ficoll-hypaque protocol and cultured in the presence of apoptosis inducers. Results In CD34 cells, there was mRNA overexpression for fas , faim and c-flip in polycythaemia vera (PV), essential thrombocythaemia (ET) and primary myelofibrosis (PMF), as well as fasl in PMF, and dr4 levels were increased in ET. In leukocytes, fas , c-flip and trail levels were increased in PV, and dr5 expression was decreased in ET. There was an association between dr5 and fasl expression and JAK2V617F mutation. PBMCs from patients with PV, ET or PMF showed resistance to apoptosis inducers. Conclusions The results indicate deregulation of apoptosis gene expression, which may be associated with MPD pathogenesis leading to accumulation of myeloid cells in MPDs.

As síndromes mielodisplásicas (SMD) são um grupo heterogêneo de distúrbios hematológicos que ocorrem mais freqüentemente em pacientes idosos e que cursa, na maioria dos casos, com anemia crônica dependente de transfusão de hemoderivados. Conseqüentemente, muitos destes pacientes passam a apresentar sobrecarga de ferro, que pode levar a danos teciduais graves. Ambas as terapias, transfusional e de quelação de ferro, quando indicadas, são importantes para manter a sobrevida e a qualidade de vida destes pacientes. A terapia de quelação de ferro está indicada especialmente nos subtipos de SMD com melhor prognóstico e sobrevida longa o suficiente para o desenvolvimento de sobrecarga de ferro com relevância clínica. A terapia de quelação de ferro apresenta algumas limitações relacionadas à necessidade de longo tempo de infusão da deferoxamina, da dificuldade de adesão pelo paciente, bem como da aquisição da bomba de infusão. O uso da deferiprona, que é um quelante oral de ferro, está contra-indicado neste grupo de pacientes, pelo risco de neutropenia e agranulocitose. O deferasirox é um novo quelante oral de ferro em estudo e que poderá, no futuro, ser uma opção adequada para os pacientes com SMD e sobrecarga de ferro. Novos estudos em pacientes com síndromes mielodisplásicas são necessários para melhor estabelecer critérios de diagnóstico da sobrecarga de ferro, bem com da terapia de quelação neste grupo. Myelodysplastic syndromes (MDSs) are a heterogeneous group of hematological disorders which are more common in the elderly and related to chronic anemia dependent on blood transfusions. Consequently, many of these patients develop iron overload which may lead to severe injury to tissues. Transfusions and chelation therapy, when indicated, are important for survival and to maintain the quality of life. Chelation therapy is indicated especially for MDS subtypes with a better prognosis and a sufficiently long survival to develop clinically relevant iron overload. Chelation therapy presents with some limitations in particular the long time required for deferoxamine infusion and the difficulties of patients to comply with treatment and to acquire an infusion pump. The clinical use of deferiprone, an oral chelator, is not indicated for MDS patients because of the risk of neutropenia and agranulocytosis. Deferasirox is a new oral chelator currently under clinical development that will probably be, in the future, an adequate option for MDS patients with iron overload. Additional studies in MDS patients are necessary to establish better diagnostic and chelation therapy criteria.

Made available in DSpace on 2021-07-14T10:28:24Z (GMT). No. of bitstreams: 0 Previous issue date: 1997-10. Added 1 bitstream(s) on 2021-07-14T11:31:09Z : No. of bitstreams: 1 S1516-31801997000500005.pdf: 1282509 bytes, checksum: ce9f96a3d352cb8355d061cb7571b0d9 (MD5) OBJETIVO: Avaliar utilidades dos sistemas de escore de Cassano e Sanz e propor outro. DESENHO: Serie de Casos. LOCAL: Hospitais universitários: EPM-UNIFESP e Faculdade de Medicina de Botucatu. PARTICIPANTES: 59 pacientes diagnosticados entre 1979 e 1992. INTERVENÇÃO: Avaliação de parâmetros clínico-laboratoriais. MENSURAÇÃO: Comparação estatística, análise uni e multivariada e curva de sobrevida atuarial. RESULTADOS: O sistema de Cassano dividiu os pacientes em alto e baixo risco (p=0.0966) enquanto o de Sanz em alto, intermediário e baixo risco (p=0.0108). A análise univariada demonstrou que hemoglobina, contagem de GB, relação EM, aumento do fígado e % de blastos na medula (MO) eram estatisticamente significantes. A regressão multivariada demonstrou como sendo significantes a % de blastos da MO (p=0.004) e os níveis de Hb (p=0.050). O nosso sistema, considerando os parâmetros da análise univariada, dividiu os pacientes em alto, intermediário e baixo risco (p=0.0038). CONCLUSÕES: O sistema de Sanz foi mais prático que o de Cassano enquanto o nosso, demonstrou valor preditivo de sobrevida e uso fácil na prática clínica. OBJECTIVE: To evaluate the score systems of Cassano and Sanz and suggest a new one. DESIGN: Case series. LOCATION: Teaching hospitals: EPM UNIFESP and Faculdade de Medicina de Botucatu. PARTICIPANTS: 59 patients diagnosed from 1979 to 1992. INTERVENTION: Evaluation of clinical-laboratorial data. MEASUREMENT: Statistical comparison, uni and multivariate analysis and actuarial survival curves. RESULTS: Cassano's system divided the patients into high and low risk (p=0.0966) while, Sanz's gave high, intermediate and low risk (p=0.0108). The univariate analysis showed hemoglobin, WBC count, E/M ratio, liver size and blast percentage in BM as statistically significant. The multivariate analysis showed blast percentage in BM (p=0.004) and Hb (p=0.050) as significant. Our system, considering the multivariate analysis data, divided the patients into high, intermediate and low risk (p=0.0038). CONCLUSIONS: Sanz's system was more functional than Cassano's, while ours showed predictive survival value and ease of use in clinical practice. Universidade Federal de São Paulo, Escola Paulista de Medicina Universidade Estadual Paulista Universidade Estadual Paulista

The prognostic value of different factors upon diagnosis of CML was analysed in 45 Philadelphia (Ph1)-positive patients. The median survival was 48 months. Univariate analysis showed 5 poor prognostic factors (male sex, under 45 years-old, bone marrow blasts greater than or equal to 10 percent, blood basophils greater than or equal to 6 percent and blood eosinophils greater than or equal to 6 percent) which provided for the development of a clinical staging system: Stage I with none or one factor and a two-year survival rate of 100 percent; Stage II with two or three factors and two-year survival of 72.2 percent; and Stage III with four or five factors and two-year survival of 0 percent (p = 0.00016). Multivariate survival analysis showed that combination of blood basophilia and bone marrow blasts had the strongest predictive relationship to survival time. We conclude that a combination of pretreatment factors identifies different risk subcategories in CML patients and is helpful in assessing the overall prognosis and the treatment approach. Avaliamos o valor prognóstico de diferentes fatores, ao diagnóstico, em 45 pacientes com LMC Ph1-positivos. A sobrevida mediana foi de 48 meses. A análise univariada identificou 5 fatores associados a pior prognóstico (sexo masculino, idade inferior a 45 anos, blastos na medula óssea maior ou igual a 10 percent, basófilos no sangue periférico maior ou igual a 6 percent e eosinófilos no sangue periférico maior ou igual a 6 percent), originando um sistema de estadiamento: estágio I com zero ou um fator e sobrevida de 100 percent em dois anos; estágio II com dois ou três fatores e sobrevida de 72,2 percent em dois anos; estágio III com 4 ou 5 fatores e sobrevida de 0 percent em dois anos (p = 0.00016). A análise multivariada demonstrou que a basofilia no sangue periférico e os blastos na medula óssea foram os fatores que melhor se correlacionaram com o tempo de sobrevida. Concluímos que a combinaçóo de fatores presentes no diagnóstico permite a identificação de diferentes grupos de risco na LMC, podendo ser útil na determinaçóo do prognóstico e na abordagem terapêutica.

Apoptosis deregulation might have a role in the pathophysiology of polycythemia vera (PV). This study evaluated Bcl-2 molecule expression in CD34+ cells and leukocytes in 12 PV patients. Gene expression was investigated by real time PCR using SybrGreen Quantitect kit and protein expression was evaluated by western-blotting. JAK2 V617F mutation was detected according to Baxter et al (2005). CD34+ cells from PV patients presented higher levels of A1 and Mcl-1 expression (median: 22.6 and 5.2, respectively) in comparison with controls (0.9 and 0.5, p=0.004 and p=0.020); while Bcl-2 and Bcl-xL expression decreased in PV patients (0.18 and 1.19) compared with controls (1.39 and 2.01, p=0.006 and p=0.020). CD34+ cells in PV patients showed an elevated Bid expression (14.4) in comparison with healthy subjects (1.0; p=0.002). Patients' leukocytes showed an A1 augmentation (7.41, p=0.001) and a reduced expression of Bax (0.19; p=0.040) and Bad (0.2; p=0.030). There was no correlation between JAK2 V617F allele burden and molecular expression. PV patients showed alterations in Bcl-2 members' expression, which may interfere with control of apoptotic machinery and contribute to disease pathogenesis.A desregulação da apoptose parece participar da fisiopatologia da policitemia vera (PV). Este estudo avaliou a expressão das moléculas da família Bcl-2 em células hematopoéticas CD34 + e leucócitos de 12 pacientes com PV. Foram realizados: a quantificação da expressão gênica por PCR em tempo real utilizando kit Sybrgreen Quantitect, avaliação da expressão de proteínas por western-blot e detecção da mutação JAK2 V617F segundo Baxter et al. (2005). Células CD34 + dos pacientes com PV apresentaram maior expressão de A1 e Mcl-1 (mediana: 22,6 e 5,2, respectivamente) em comparação com controles (0,9 e 0,5, p = 0,004 e p = 0,020) e expressão de Bcl-2 e Bcl-xL diminuída nestes pacientes (0,18 e 1,19) em relação aos controles (1,39 e 2,01, p = 0,006 e p = 0,020). Células CD34 + dos pacientes com PV mostraram expressão elevada de bid (14,4) em comparação aos controles (1,0; p = 0,002). Leucócitos dos pacientes mostraram aumento de A1 (7,41, p = 0,001) e expressão reduzida do Bax (0,19; p = 0,04) e Bad (0,2; p = 0,030). Não houve correlação entre percentagem de alelos JAK2 V617F mutados e expressão molecular. Pacientes com PV apresentaram alterações na expressão de moléculas Bcl-2 que podem interferir no controle da apoptose e contribuir para a patogênese da doença.

Abstract 5057 Background: Polycythaemia vera (PV) is a clonal disorder characterized by an accumulation of normal red and white cells, platelets, and their progenitors in absence of a definable stimulus. Despite the advances in PV diagnosis its physiopathology remains not well elucidated. Apoptosis deregulation seems to contribute to disease establishment. MicroRNAs are small noncoding RNAs, post transcriptional repressors of genes by deadenilation, which play relevant roles in regulation of apoptotic machinery. Here we investigate the relation of apoptosis deregulation and apoptomirs expression in PV patients. Aims: To quantify the apoptomirs −16, −21, −15a, −26a, 130b, 29c and let-7d expression in peripheral leukocytes and CD34+ hematopoietic stem cells (HSC) in Polycythemia Vera (PV) patients and to correlate with targets genes expression data. Subjects and Methods: 30 PV patients, 13 men and 17 women with a mean age (ma) of 64. 7y. 30 healthy subjects, 13 males and 17 females, ma=60. 2y and 23 bone marrow donors, 14 males and 9 females, ma=32. 6y. Peripheral leukocytes were obtained by Haes-Steril method and CD34+ hematopoietic stem cells were enriched by using the magnetically activated cell sorting, total RNA was extracted according to Trizol® method and High Capacity® Kit was used to synthesize cDNA. The microRNAs and apoptosis-related genes expression quantification was performed by real time PCR. Results were given as 2-ΔΔCt and statistical analyses were carried out by Mann-Whitney and Spearman tests. Western Blot was applied to detect Bcl-2 protein expression. Results: miR-16 and miR21 levels were increased in PV leukocytes (median= 3. 45 and 6. 97 respectively)) and CD34+ HSC (median= 3. 86 and 4. 07 respectively) in comparison to controls (control leukocytes median= 0. 483 and 0. 989 respectively) (CD34+ HSC median= 0. 978 and 1. 15, respectively) (p= 0. 0001 and 0. 0001 in leukocytes) and (p= 0. 0001 and 0. 0005 in CD34+ HSC, respectively). The Bcl-2 gene expression was decreased in PV leukocytes (m= 0.18) when compared to controls (m= 1. 03; p= 0. 019). In addition we found in CD34+ HSC negative correlation between miR-21 and anti-apoptotic gene Bcl-2 (r= −0. 417; p= 0. 033) and between miR16 and anti-apoptotic gene Bcl-2(r= −0. 384; p=0. 046). Bcl-2 western blot showed half expression in PV leukocytes when compared to controls. Conclusions: The results indicate the apoptomirs expression is linked to apoptosis deregulation in Polycythemia Vera physiopathology. Disclosures: No relevant conflicts of interest to declare.

Background Essential Thrombocythemia (ET) and Primary Myelofibrosis (PMF) are Chronic Myeloproliferative Neoplasms (MPN) characterized by clonal myeloproliferation/myeloaccumulation without cell maturation impairment. The JAK2 V617F mutation and PRV1 gene overexpression may contribute to MPN physiopathology. We hypothesized that deregulation of the apoptotic machinery may also play a role in the pathogenesis of ET and PMF. In this study we evaluated the apoptosis-related gene and protein expression of BCL2 family members in bone marrow CD34+ hematopoietic stem cells (HSC) and peripheral blood leukocytes from ET and PMF patients. We also tested whether the gene expression results were correlated with JAK2 V617F allele burden percentage, PRV1 overexpression, and clinical and laboratory parameters. Results By real time PCR assay, we observed that A1, MCL1, BIK and BID, as well as A1, BCLW and BAK gene expression were increased in ET and PMF CD34+ cells respectively, while pro-apoptotic BAX and anti-apoptotic BCL2 mRNA levels were found to be lower in ET and PMF CD34+ cells respectively, in relation to controls. In patients' leukocytes, we detected an upregulation of anti-apoptotic genes A1, BCL2, BCL-X L and BCLW. In contrast, pro-apoptotic BID and BIM EL expression were downregulated in ET leukocytes. Increased BCL-XL protein expression in PMF leukocytes and decreased BID protein expression in ET leukocytes were observed by Western Blot. In ET leukocytes, we found a correlation between JAK2 V617F allele burden and BAX, BIK and BAD gene expression and between A1, BAX and BIK and PRV1 gene expression. A negative correlation between PRV1 gene expression and platelet count was observed, as well as a positive correlation between PRV1 gene expression and splenomegaly. Conclusions Our results suggest the participation of intrinsic apoptosis pathway in the MPN physiopathology. In addition, PRV1 and JAK2 V617F allele burden were linked to deregulation of the apoptotic machinery.