scholarly journals Molecular profile of CD34+ stem/progenitor cells according to JAK2V617F mutation status in essential thrombocythemia

Leukemia ◽  
2009 ◽  
Vol 23 (5) ◽  
pp. 997-1000 ◽  
Author(s):  
L Catani ◽  
R Zini ◽  
D Sollazzo ◽  
E Ottaviani ◽  
A M Vannucchi ◽  
...  
Keyword(s):  
Progenitor Cells ◽  
Essential Thrombocythemia ◽  
Jak2v617f Mutation ◽  
Molecular Profile ◽  
Mutation Status

Selective Targeting of the JAK2V617F Mutation in Polycythemia Vera and Essential Thrombocythemia by ITF2357, a Novel Histone Deacetylase Inhibitor.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 555-555 ◽  
Author(s):  
Vittoria Guerini ◽  
Valentina Barbui ◽  
Orietta Spinelli ◽  
Anna Salvi ◽  
Chiara Dellacasa ◽  
...  
Keyword(s):  
Polycythemia Vera ◽  
Progenitor Cells ◽  
Histone Deacetylase ◽  
Essential Thrombocythemia ◽  
Colony Formation ◽  
Mononuclear Cells ◽  
Jak2v617f Mutation ◽  
Wild Type ◽  
Blood Mononuclear Cells ◽  
Hel Cells

Abstract A somatic point mutation in the JAK2 gene (JAK2V617F) is the key pathogenetic lesion of Polycythemia Vera (PV) and Essential Thrombocythemia (ET) and a significant effort is now paid to identify drugs which may be able to interfere with the JAK2V617Fmutated protein. Among others, one potentially interesting drug family is represented by the Histone Deacetylase Inhibitors (HDACi), which may modify the chromatin structure and ultimately the transcription of many genes, the cell cycle progression and the programmed cell death. ITF2357 is a new HDACi (Italfarmaco, Milan, SpA) that shows a potent anti-proliferative and pro-apoptotic activity against acute myeloid leukemia and multiple myeloma cells and little toxicity against normal hematopoietic and mesenchymal stem cells (Golay J et al.: Leukemia 2007). The most common side effects after its administration to normal volounteers and MM patients are represented by thrombocytopenia and gastrointestinal toxicity. These observations prompted us to investigate the inhibitory activity played by ITF2357 on the autonomous proliferation of cells obtained by PV and ET patients carrying the JAK2V617F mutation and to elucidate the mechanism of action of this inhibition. We first investigated the effect of ITF2357 on the clonogenic activity of cell lines carrying or not the JAK2V617F mutation. ITF2357 inhibited colony formation of HEL cells (an erythroleukemia cell line carrying a JAK2V617F homozygous mutation) with an IC50 of about 0.001 μM. In contrast, the doses of drug required to block colony formation by K562, KG1, NB4 and GF-D8 (all negative for the JAK2V617F mutation) were 100–500 fold higher (IC50 ranging from 0.1 to 0.5 μM). Clonogenic assays were then performed using blood mononuclear cells obtained from 4 PV and 7 ET patients, all carrying the JAK2V617F mutation. Either in the presence or absence (EEC assay) of exogenous growth factors, colonies obtained from JAK2V617F mutated progenitor cells were inhibited at much lower doses of ITF2357 (IC50 0.001 μM) as compared to colonies obtained from JAK2 wild type progenitor cells (IC50 0.1–0.25 μM). When single colonies were picked randomly and analyzed by PCR for the presence of wild type or mutated JAK2V617F alleles, a striking reduction of mutated colonies was detected when ITF2357 was added at 0.001 μM and 0.01 μM, confirming that low doses of ITF357 allow the preferential outgrowth of unmutated over mutated colonies from the peripheral blood mononuclear cells of PV patients bearing JAK2V617F. By Western blotting we also showed that ITF2357 treatment for 24 hours, led to virtual disappearance of total and phosphorylated JAK2V617F in HEL cells whereas it did not affect the wild type JAK2 protein in the control K562 cell line, even after 48 hours in the same conditions. Down-modulation of mutated JAK2V617F was accompanied by specific disappearance of p-STAT5 protein. Finally, by Real time PCR analysis of PV cells treated with ITF2357 for 24 hours, we could demonstrate that this drug does not affect JAK2 mRNA but rather it induces a significant decrease of the PRV1 gene, a known JAK2 target. These data suggest that ITF2357 down-modulates the mutated JAK2V617F protein by post-transcriptional mechanisms and that is followed by inhibition of p-STAT5 protein and PRV1 gene expression. The specific inhibition induced by ITF2357 on cells bearing the JAK2V617F mutation underlines its therapeutic potential as a new drug for PV and ET patients.

JAK2V617F Mutation in Korean Patients with Essential Thrombocythemia

2007 ◽  
Vol 27 (2) ◽  
pp. 77-80 ◽  
Author(s):  
Jeong-Yeal Ahn ◽  
Soo-Jin Yoo ◽  
Soo-Mee Bang ◽  
Pil-Whan Park ◽  
Yiel-Hea Seo ◽  
...  
Keyword(s):  
Essential Thrombocythemia ◽  
Jak2v617f Mutation ◽  
Korean Patients

INCREASED SPONTANEOUS NUMBER OF MEGAKARYOCYTE COLONIES IN ESSENTIAL THROMBOCYTHEMIA (ET)

1987 ◽  
Author(s):  
J F Deschamps ◽  
E Bodevin ◽  
J P Caen
Keyword(s):  
Platelet Count ◽  
Human Serum ◽  
Progenitor Cells ◽  
Platelet Function ◽  
Essential Thrombocythemia ◽  
Antiplatelet Agents ◽  
Iron Therapy ◽  
Plasma Clot ◽  
Megakaryocyte Progenitors

Megakaryocytes were grown from medullary progenitor cells using the plasma clot technique, with 5 % human serum and with or without 2,5 % PHA-LCM. Using this technique megakaryocyte cultures were done in 5 patients essential thrombocythemia (ET) ( platelet count :0,6 x 106 to 1,4 x 106 /μi) before chemotherapy and antiplatelet agents and in 2 patients with secondary thrombocytosis (ST) (platelet count : 0,65 x lO6 and 0,8 x 106 /μi) corrected after effective anti-bacterial or iron therapy. The results were as followsx number of colonies mean number (in brackets) of cells per colonyIt appears therefore that in ET, megakaryocyte progenitors grow without PHA-LCM and show however a better proliferation in its presence. On the contrary in ST, PHA-LCM is required for obtaining a 6 times increase of MK colonies. The effect of MK growth under chemotherapy is reported in some of the patients studied before treatment and results analyzed and compared to platelet function involvement

scholarly journals Cultures of myeloid progenitor cells in pediatric essential thrombocythemia

Leukemia ◽  
2002 ◽  
Vol 16 (9) ◽  
pp. 1876-1877 ◽  
Author(s):  
L Florensa ◽  
L Zamora ◽  
C Besses ◽  
JJ Ortega ◽  
P Bastida ◽  
...  
Keyword(s):  
Progenitor Cells ◽  
Essential Thrombocythemia ◽  
Myeloid Progenitor ◽  
Myeloid Progenitor Cells

JAK2 Mutation Status in Granulocytes, Platelets and Erythrocytes Differs Between Polycythemia Vera and Essential Thrombocythemia

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 5228-5228
Author(s):  
Kohtaro Toyama ◽  
Norifumi Tsukamoto ◽  
Akio Saito ◽  
Hirotaka Nakahashi ◽  
Yoko Hashimoto ◽  
...  
Keyword(s):  
T Cells ◽  
Polycythemia Vera ◽  
Essential Thrombocythemia ◽  
Mononuclear Cells ◽  
Rna Extraction ◽  
Jak2 V617f ◽  
Janus Kinase ◽  
Jak2 V617f Mutation ◽  
Mutation Status ◽  
V617f Mutation

Abstract Background The gain-of-function point mutation in Janus kinase 2 exon 14 gene (JAK2-V617F) influences the diagnosis of bcr/abl-negative chronic myeloproliferative disorders (CMPDs). We previously reported that analyzing platelets is advantageous in detecting the JAK2-V617F mutation, particularly in essential thrombocythemia (ET), when compared to granulocytes. However, there have been few reports analyzing the JAK2-V617F mutation in erythroid lineage cells, and comparing the mutation status in all three lineages. Method Study protocols were approved by the Institutional Review Board of Gunma University Hospital, and written informed consent was obtained from all the patients. Heparinized peripheral blood was obtained from 113 patients with CMPDs (82 with ET, 25 with polycythemia vera (PV), and 6 with primary myelofibrosis (PMF). After centrifugation, platelets were collected from the upper plasma layer. Remaining blood was mixed with Hank’s Balanced Salt Solution and was subjected to Ficoll-Hypaque density gradient centrifugation. Granulocytes were obtained from the pellet. Mononuclear cells were resuspended in RPMI 1640 medium; 5 × 105 cells were plated in duplicate in 1 ml of methylcellulose medium and cultured in a humidified atmosphere of 5 % of carbon dioxide at 37°C for 14 days in the presence of erythropoietin to obtain erythroid colonies (BFU-E). T-cells were obtained from the remaining mononuclear cells using anti-CD3 immunoconjugated magnetic beads. After extraction of DNA from granulocytes, T-cells and BFU-E, and RNA extraction from granulocytes and platelets, PCR amplification and sequencing of exon 14 of the Jak2 gene was performed to confirm the presence of JAK2-V617F mutations. To confirm the mutation status of granulocytes, T-cells and BFU-E, allele-specific PCR (AS-PCR) was performed. Results For ET, 57 out of 82 patients (69.5%) had the JAK2-V617F mutation. In the 57 patients with the JAK2-V617F mutation, 38 (67%) had the mutation in all three lineages, 5 had the mutation in granulocytes and platelets, 2 had the mutation in platelets and BFU-E, 10 patients had the mutation only in platelets and 2 patients had the mutation only in BFU-E. In contrast, for PV, 22/25 patients (88%) had the JAK2-V617F mutation. Of note, in 22 patients having JAK2-V617F mutation, 20 (91%) were JAK2-V617F mutation-positive in all three lineages; the remaining two patients had the mutation in either platelets or BFU-E. The frequency of JAK2-V617F in all three lineages was significantly higher in PV than in ET (p < 0.05). For PMF, 5 of 6 patients had the mutation in granulocytes, and 3 of these had it in all three lineages. Conclusion Among JAK2-V617F mutation-positive CMPDs, most PV patients had the JAK2-V617F mutation in all three lineages, thus suggesting that the JAK2-V617F mutation occurs in progenitor cell(s) common to granulocytes, platelets and erythrocytes. In contrast, only 67% of ET patients had the JAK2-V617F mutation in three lineages; in the remaining cases, not all of the three lineages have the mutation. This difference in lineages showing the JAK2-V617F mutation between the ET and PV may be related to the pathophysiological differences in ET and PV. Furthermore, the heterogeneous mutation status in ET may be related to its heterogeneous clinical manifestation.

JAK2V617F Complete Molecular Remission in Long-Term Follow-up of Patients with Polycythemia Vera and Essential Thrombocythemia Treated with Ruxolitinib

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 3185-3185
Author(s):  
Lisa Pieri ◽  
Alessandro Pancrazzi ◽  
Annalisa Pacilli ◽  
Claudia Rabuzzi ◽  
Giada Rotunno ◽  
...  
Keyword(s):  
Polycythemia Vera ◽  
Essential Thrombocythemia ◽  
Research Funding ◽  
Jak2v617f Mutation ◽  
Prolonged Treatment ◽  
Molecular Response ◽  
Molecular Remission ◽  
Allele Burden ◽  
Jak2v617f Allele Burden

Abstract Polycythemia vera (PV) and essential thrombocythemia (ET) are myeloproliferative neoplasms (MPN) characterized by the presence of JAK2V617F mutation in >95% and 60% of patients (pts), respectively. This mutation usually affects one allele in ET while most PV pts are homozygous due to mitotic recombination. Acquisition of the JAK2V617F mutation is strongly associated with the germline 46/1 predisposition haplotype. Ruxolitinib is a JAK1/JAK2 inhibitor recently approved for myelofibrosis (MF) and under investigation in PV and ET pts intolerant or resistant to hydroxyurea. We enrolled 24 pts, 11 with PV and 13 with ET, in the phase II INCB18424-256 trial that overall included 34 PV and 39 ET pts. 21/24 pts were still on treatment at 5 years (yr), of which 19 JAK2V617F mutated. Results of the PV cohort have been reported recently (Verstovsek et al. Cancer, 2014): with a median follow up of 35 months (mo), the JAK2V617F allele burden decreased by a mean of 8%, 14%, and 22%, respectively, after 12, 24 and 36 mo. The proportion of pts who achieved a reduction ≥50 % at any time during the 1st yr, 2nd yr, and 3rd yr were 5.9%, 14.7%, and 23.5%, respectively, but no patients achieved a complete remission. In our series of pts we evaluated the JAK2V617F allele burden by two RTQ-PCR methods, according to Lippert (sensitivity, 0.8%) and to Larsen (sensitivity, 0.08%) method. We also analysed by next generation sequencing (NGS; Ion Torrent platform) a series of MPN-associated mutations including TET2, ASXL1, IDH1/2, LNK, CBL, SRSF2, EZH2 and MPL at baseline and at 5 yr of treatment in ruxolitinib treated pts who achieved a >25% JAK2V617F allele burden reduction at 5 yr (n=13/19). JAK2V617F allele burden decreased by a mean of 7%, 11%, and 19% at 12, 24 and 36 mo, and decreased further by a mean of 28% after 60 mo. Three (1 PV, 2 ET) of 19 pts (16%) achieved a 50% or greater allele burden reduction after 2 yr; no additional pts achieved this degree of allele burden reduction even in prolonged follow up. These 3 pts further improved their molecular response to a complete molecular response (CMR) after 5 yr of treatment. Their mean JAK2V617F allele burden was 46.6% at baseline, 28.3%, 16.3%, 8.7% and 0% after 1 yr, 2 yr, 3 yr and 5 yr, respectively. The JAK2 CMR was confirmed in at least one independent sample at 3 mo after first discovery. At this last timepoint, the PV pt was in complete haematological remission according to ELN criteria, the 2 ET pts were in partial remission due to platelet count still >400x109/L: 422x109/L and 812x109/L, respectively. BM histopathology in the 2 ET pts at 5 yr, while they were in CMR, showed still evidence of megakaryocyte hyperplasia. In the PV pt, histopathology at 5 yr is pending; evaluation at 3 yr, a time when she was in complete hematologic remission and JAK allele burden had decreased from 69 to 8%, showed normalization of cellularity, megakaryocyte and myeloid lineage compared to baseline but still slight erythroid hyperplasia. All 3 pts had normal karyotype at baseline that remained unchanged thereafter. CMR for JAK2V617F was confirmed by NGS. The 2 ET pts achieving CMR did not show any additional mutations, while the PV pts presented a TET2 Y867H mutation with an allele burden of 48.9% and 52%, respectively at baseline and 5 yr. No recurrent mutations in genes other than JAK2 were found in all other examined cases at baseline or at 5 yr. In 3 informative pts, we also analysed the proportion of JAK2V617F homozygous, heterozygous and wild type clones by the method of Hasan et al (Leukemia 2013) based on allelic discrimination of 46/1 haplotype and JAK2. We found that JAK2V617F/V617F clones were reduced by a mean of 95.5%, JAK2V617F/WT showed an uneven trend with a mean reduction of 45.54% while JAK2WT/WT conversely increased (mean 61.43%) at 5 yr, suggesting that in a subset a patients who present significant reduction of VF allele burden ruxolitinib may preferentially target the homozygous clones. Until now, complete molecular remission in PV pts has been described only in patients treated with interferon. Our data suggest that a subset of pts who present a rapid and sustained reduction of the JAK2V617F allele burden under ruxolitinib may eventually reach a condition of CMR with prolonged treatment. However, similar to findings with interferon, mutations establishing clonality, such as in TET2, may still persist in patients who eventually show the disappearance of JAK2V617F mutated subclones. Disclosures Verstovsek: Incyte: Research Funding. Vannucchi:Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding.

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