Project description:BackgroundMyeloid neoplasm (MN) with eosinophilia and rearrangement of platelet-derived growth factor receptor beta (PDGFRB) shows a good therapeutic response to imatinib in adults. MN is rarely found in children, and the efficacy of imatinib on pediatric patients remain unclear.Case summaryWe report 2 pediatric cases diagnosed with MN with eosinophilia and PDGFRB rearrangement who were treated with imatinib. Case 1 was a 1-year-old girl admitted to the hospital because of "abdominal distension with hyperleukocytosis for 3 mo". She had leukocytosis, anemia, and eosinophilia (the absolute eosinophil count (AEC) was 8960/μL), and her fluorescence in situ hybridization (FISH) test revealed that PDGFRB rearrangement was detected in 70% of 500 interphase cells. Case 2 was a 2-year-old girl admitted to the hospital because of "recurrent fever and rashes for 1 mo". Her blood cell count showed an AEC of 3540/μL. The FISH test revealed that PDGFRB rearrangement was detected in 71% of 500 interphase cells. Both patients were diagnosed as MN with eosinophilia and PDGFRB rearrangement. Imatinib was added into their treatment regimen. As expected, complete hematologic remission was achieved after 1 mo of treatment, and symptoms disappeared.ConclusionAlthough MN with eosinophilia and PDGFRB rearrangement usually occurs in adults, it can be found in children. The therapeutic benefits of imatinib in these 2 pediatric patients were consistent with its reported effects in adult patients.
Project description:ETV6-ABL1 is a rare gene fusion with oncogenic properties, reported so far in 28 patients presenting a variety of haematological malignancies associated with clinical outcome, including chronic myeloid leukaemia (CML), acute myeloid leukaemia (AML), acute lymphoblastic leukaemia (ALL) and chronic myeloproliferative neoplasm (cMPN). Here we report on a 46-year-old female who presented with Philadelphia negative CML, positive for the ETV6-ABL1 fusion. Whole genome screening carried out with oligonucleotide arrays showed a subtle loss at 12p13 and cryptic imbalances within the 9q34.3 region in a highly unstable genome. FISH mapping with custom BAC probes identified two breakpoints 5 Mb apart within the 9q34 region, together with a break at 12p13. While FISH with commercial BCR-ABL1 probes failed to detect any ABL1 changes, the ETV6 break-apart probe conclusively identified the ETV6-ABL1 fusion thus determining the probe's role as the primary diagnostic FISH test for this chimeric oncogene. In addition, we confirm the association of the ETV6-ABL1 fusion with imatinib resistance reported so far in three other patients, while recording excellent response to the 2nd generation tyrosine kinase inhibitor (TKI) nilotinib. In summary, we highlight the value of ETV6 FISH as a diagnostic test and the therapy resistance of ETV6-ABL1 positive disorders to imatinib.
Project description:Plasma cell dyscrasias and myeloproliferative neoplasms (MPN) are hematologic malignancies arising from two distinct hematopoietic cell lineages. They rarely occur concomitantly. Here, we report a case of a patient with a recent diagnosis of a JAK2 V617F positive MPN who presented with a new diagnosis of plasma cell leukemia. The patient had presented to the hospital with a leukocytosis predominantly comprised of plasma cells, followed by work-up involving peripheral blood flow cytometry, FISH analysis, and bone-marrow biopsy. FISH analysis was suggestive of a common progenitor cell for these distinct hematologic malignancies. To our knowledge, this case represents the second reported instance of a concomitant JAK2 positive MPN with primary plasma cell leukemia.
Project description:Platelet-derived growth factors (PDGFs) and their receptors (PDGFRs) are prototypic growth factors and receptor tyrosine kinases which have critical functions in development. We show that PDGFs share a conserved region in their prodomain sequences which can remain noncovalently associated with the mature cystine-knot growth factor domain after processing. The structure of the PDGF-A/propeptide complex reveals this conserved, hydrophobic association mode. We also present the structure of the complex between PDGF-B and the first three Ig domains of PDGFRbeta, showing that two PDGF-B protomers clamp PDGFRbeta at their dimerization seam. The PDGF-B:PDGFRbeta interface is predominantly hydrophobic, and PDGFRs and the PDGF propeptides occupy overlapping positions on mature PDGFs, rationalizing the need of propeptides by PDGFs to cover functionally important hydrophobic surfaces during secretion. A large-scale structural organization and rearrangement is observed for PDGF-B upon receptor binding, in which the PDGF-B L1 loop, disordered in the structure of the free form, adopts a highly specific conformation to form hydrophobic interactions with the third Ig domain of PDGFRbeta. Calorimetric data also shows that the membrane-proximal homotypic PDGFRalpha interaction, albeit required for activation, contributes negatively to ligand binding. The structural and biochemical data together offer insights into PDGF-PDGFR signaling, as well as strategies for PDGF-antagonism.
Project description:Arterial cardiovascular events are the leading cause of death in patients with JAK2V617F myeloproliferative neoplasms (MPNs). However, their mechanisms are poorly understood. The high prevalence of myocardial infarction without significant coronary stenosis or atherosclerosis in patients with MPNs suggests that vascular function is altered. The consequences of JAK2V617F mutation on vascular reactivity are unknown. We observe here increased responses to vasoconstrictors in arteries from Jak2V617F mice resulting from a disturbed endothelial NO pathway and increased endothelial oxidative stress. This response was reproduced in WT mice by circulating microvesicles isolated from patients carrying JAK2V617F and by erythrocyte-derived microvesicles from transgenic mice. Microvesicles of other cellular origins had no effect. This effect was observed ex vivo on isolated aortas, but also in vivo on femoral arteries. Proteomic analysis of microvesicles derived from JAK2V617F erythrocytes identified increased expression of myeloperoxidase as the likely mechanism accounting for their effect. Myeloperoxidase inhibition in microvesicles derived from JAK2V617F erythrocytes suppressed their effect on oxidative stress. Antioxidants such as simvastatin and N-acetyl cysteine improved arterial dysfunction in Jak2V617F mice. In conclusion, JAK2V617F MPNs are characterized by exacerbated vasoconstrictor responses resulting from increased endothelial oxidative stress caused by circulating erythrocyte-derived microvesicles. Simvastatin appears to be a promising therapeutic strategy in this setting.
Project description:Increased immature neovessels contribute to plaque growth and instability. Here, we investigated a method to establish functional and stable neovessel networks to increase plaque stability. Rabbits underwent aortic balloon injury and were divided into six groups: sham, vector and lentiviral transfection with vascular endothelial growth factor-A (VEGF)-A, fibroblast growth factor (FGF)-2, platelet-derived growth factor (PDGF)-BB and FGF-2 + PDGF-BB. Lentivirus was percutaneously injected into the media-adventitia of the abdominal aorta by intravascular ultrasound guidance, and plaque-rupture rate, plaque-vulnerability index and plaque neovessel density at the injection site were evaluated. Confocal microscopy, Prussian Blue assay, Evans Blue, immunofluorescence and transmission electron microscopy were used to assess neovessel function and pericyte coverage. To evaluate the effect of FGF-2/PDGF-BB on pericyte migration, we used the mesenchymal progenitor cell line 10T1/2 as an in vitro model. VEGF-A- and FGF-2-overexpression increased the number of immature neovessels, which caused intraplaque haemorrhage and inflammatory cell infiltration, eventually resulting in the plaque vulnerability; however, FGF-2/PDGF-BB induced mature and functional neovessels, through increased neovessel pericyte coverage. Additionally, in vitro analysis of 10T1/2 cells revealed that FGF-2/PDGF-BB induced epsin-2 expression and enhanced the VEGF receptor-2 degradation, which negatively regulated pericyte function consistent with the in vivo data. These results showed that the combination of FGF-2 and PDGF-BB promoted the function and maturation of plaque neovessels, thereby representing a novel potential treatment strategy for vulnerable plaques.
Project description:Vascular endothelial growth factor (VEGF-A) is a crucial stimulator of vascular cell migration and proliferation. Using bone marrow-derived human adult mesenchymal stem cells (MSCs) that did not express VEGF receptors, we provide evidence that VEGF-A can stimulate platelet-derived growth factor receptors (PDGFRs), thereby regulating MSC migration and proliferation. VEGF-A binds to both PDGFRalpha and PDGFRbeta and induces tyrosine phosphorylation that, when inhibited, results in attenuation of VEGF-A-induced MSC migration and proliferation. This mechanism was also shown to mediate human dermal fibroblast (HDF) migration. VEGF-A/PDGFR signaling has the potential to regulate vascular cell recruitment and proliferation during tissue regeneration and disease.
Project description:We describe a novel ERBB1/EGFR somatic mutation (p. C329R; c.985 T > C) identified in a patient with JAK2V617F Polycythaemia Vera (PV). This substitution affects a conserved cysteine residue in EGFR domain 2 and leads to the formation of a ligand-independent covalent receptor dimer, associated with increased transforming potential. Aberrant signalling from the EGFRC329R receptor is cell type-dependent and in the TF1.8 erythroid cell line expression of this mutant suppresses EPO-induced differentiation. Clonal analysis shows that the dominant JAK2V617F-positive clone in this PV patient harbors EGFRC329R, thus this mutation may contribute to clonal expansion. Somatic mutations affecting other ERBB and related receptor tyrosine kinases are observed in myeloproliferative neoplasms (MPN), and we show elevated EGFR levels in MPN samples, consistent with previous reports. Thus activation of this group of receptors, via multiple mechanisms, may contribute to clonal growth and survival of the JAK2V617F disease clone in MPN.
Project description:IntroductionThe PCM1-JAK2 rearrangement is generated through the t(8; 9)(p22; p24) translocation event. The myeloid/lymphoid neoplasms with eosinophilia (MLN-eo) with PCM1-JAK2 rearrangement is the common types of MLN-eo with tyrosine kinase fusion genes (MLN-Eo-tk). MLN-Eo with PCM1-JAK2 rearrangement is a rare disease with a poor prognosis and no unified treatment guidelines. The response of disease to ruxolitinib may be transient and it may only serve as a temporary treatment prior to transplantation.Case presentationWe report 1 patient diagnosed with MLN-Eo with PCM1-JAK2 rearrangement who exhibited resistance to ruxolitinib, subsequently received pegylated interferon (Peg-IFN) and lenalidomide. The Peg-IFN was discontinued due to adverse effects; the patient has been receiving lenalidomide monotherapy for a duration exceeding 2 years, achieving complete hematologic remission and molecular response, significant amelioration of symptoms, as well as regression of hepatosplenomegaly.ConclusionA case of MLN-Eo with PCM1-JAK2 rearrangement underwent continuous oral lenalidomide monotherapy for over 2 years. The patient achieved complete hematologic remission and molecular response during the long-term follow-up; however, a complete molecular remission was not attained. The underlying mechanism of lenalidomide in these diseases necessitates further comprehensive investigation through fundamental research and clinical trials.