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Depletion of STAT5 blocks TEL-SYK-induced APMF-type leukemia with myelofibrosis and myelodysplasia in mice.

Sprissler C, Belenki D, Maurer H, Aumann K, Pfeifer D, Klein C, Müller TA, Kissel S, Hülsdünker J, Alexandrovski J, Brummer T, Jumaa H, Duyster J, Dierks C - Blood Cancer J (2014)

Bottom Line: LKS cells were reduced and all subsets (LT/ST/MPP) showed reduced proliferation rates.SYK inhibitor treatment (R788) of diseased TEL-SYK mice reduced leukocytosis, spleen and liver infiltration, enhanced the hematocrit and prolonged survival time, but could not significantly reduce myelofibrosis.Stat5 was identified as a major downstream mediator of TEL-SYK in vitro as well as in vivo.

View Article: PubMed Central - PubMed

Affiliation: 1] Department of Hematology/Oncology, University Medical Center Freiburg, Freiburg, Germany [2] University of Freiburg, Schaenzlestrasse 1, Freiburg, Germany.

ABSTRACT
The spleen tyrosine kinase (SYK) was identified as an oncogenic driver in a broad spectrum of hematologic malignancies. The in vivo comparison of three SYK containing oncogenes, SYK(wt), TEL-SYK and IL-2-inducible T-cell kinase (ITK)-SYK revealed a general myeloexpansion and the establishment of three different hematologic (pre)diseases. SYK(wt) enhanced the myeloid and T-cell compartment, without leukemia/lymphoma development. ITK-SYK caused lethal T-cell lymphomas and the cytoplasmic TEL-SYK fusion induced an acute panmyelosis with myelofibrosis-type acute myeloid leukemia (AML) with up to 50% immature megakaryoblasts infiltrating bone marrow, spleen and liver, additional MPN features (myelofibrosis and granulocyte expansion) and MDS stigmata with megakaryocytic and erythroid dysplasia. LKS cells were reduced and all subsets (LT/ST/MPP) showed reduced proliferation rates. SYK inhibitor treatment (R788) of diseased TEL-SYK mice reduced leukocytosis, spleen and liver infiltration, enhanced the hematocrit and prolonged survival time, but could not significantly reduce myelofibrosis. Stat5 was identified as a major downstream mediator of TEL-SYK in vitro as well as in vivo. Consequently, targeted deletion of Stat5 in vivo completely abrogated TEL-SYK-induced AML and myelofibrosis development, proving Stat5 as a major driver of SYK-induced transformation. Our experiments highlight the important role of SYK in AML and myelofibrosis and prove SYK and STAT5 inhibitors as potent treatment options for those diseases.

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TEL–SYK induces an AML with features of human APMF in mice. (a) Images from hematoxylin and eosin-stained BM, spleen and liver slides from control, SYKwt, TEL–SYK and ITK–SYK mice. ◂shows dysplastic and immature megakaryocytes /megakaryoblasts infiltrating BM, spleens and the liver of TEL–SYK mice. Bars, 50 μm. (b) Periodic acid–Schiff (PAS) stain of BM and spleens from control and TEL–SYK mice highlight the infiltrating megakaryoblasts in TEL–SYK mice. (c) Reticulin stain of BM and spleens of diseased TEL–SYK mice compared with controls display a strong fibrosis (II–III) in both organs (right panel). Bars, 50 μm.
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fig3: TEL–SYK induces an AML with features of human APMF in mice. (a) Images from hematoxylin and eosin-stained BM, spleen and liver slides from control, SYKwt, TEL–SYK and ITK–SYK mice. ◂shows dysplastic and immature megakaryocytes /megakaryoblasts infiltrating BM, spleens and the liver of TEL–SYK mice. Bars, 50 μm. (b) Periodic acid–Schiff (PAS) stain of BM and spleens from control and TEL–SYK mice highlight the infiltrating megakaryoblasts in TEL–SYK mice. (c) Reticulin stain of BM and spleens of diseased TEL–SYK mice compared with controls display a strong fibrosis (II–III) in both organs (right panel). Bars, 50 μm.

Mentions: BM from TEL–SYK mice showed signs of multilineage dysplasia as seen in myelodysplastic syndrome, with hypoplasia of erythrocytes showing nuclear fragmentation, irregular nuclear contours and abnormal mitotic figures. Myelopoesis showed abnormal nuclear maturation with open chromatin, lobulated nuclei and hypogranulation. Immature megakaryocytes/megakaryoblasts were strongly increased reaching up to 50% of total cell counts and partially displayed multiple separated nuclei or unlobulated nuclei as well as micromegakaryocytes (Figure 3a, Supplementary Figure S7). Megakaryocytes were mainly periodic acid–Schiff stain positive (Figure 2b) and were organized in clusters. The immature megakaryoblasts in the BM were phenotypically identical with blasts seen in the peripheral blood. Reticulin staining showed a grade 2–3 myelofibrosis, at least partially explaining the reduced total cell counts in TEL–SYK mice (Figure 3c, Supplementary Figure S7). TEL–SYK spleens had lost their normal follicular architecture, were strongly fibrotic and were infiltrated with myeloid cells, predominantly consisting of mature granulocytes, dysplastic erythrocytes and clusters of dysplastic and immature megakaryocytes (Figure 3c). The same cell types also infiltrated the liver (Figure 3a). Taken together and according to the Bethesda classification of nonlymphoid hematopoietic neoplasms in mice44 (myeloid disorders), the TEL–SYK phenotype in the majority of mice can be classified as AML with features of human acute panmyelosis with myelofibrosis (APMF). Due to the frequent MDS features, we also have to consider the diagnosis of a myelodysplastic syndrome with features of human refractory anemia with excess blasts and fibrosis (RAEB-F) and at least one mouse, with more than 50% megakaryoblasts in the BM can be diagnosed as megakaryocytic leukemia.


Depletion of STAT5 blocks TEL-SYK-induced APMF-type leukemia with myelofibrosis and myelodysplasia in mice.

Sprissler C, Belenki D, Maurer H, Aumann K, Pfeifer D, Klein C, Müller TA, Kissel S, Hülsdünker J, Alexandrovski J, Brummer T, Jumaa H, Duyster J, Dierks C - Blood Cancer J (2014)

TEL–SYK induces an AML with features of human APMF in mice. (a) Images from hematoxylin and eosin-stained BM, spleen and liver slides from control, SYKwt, TEL–SYK and ITK–SYK mice. ◂shows dysplastic and immature megakaryocytes /megakaryoblasts infiltrating BM, spleens and the liver of TEL–SYK mice. Bars, 50 μm. (b) Periodic acid–Schiff (PAS) stain of BM and spleens from control and TEL–SYK mice highlight the infiltrating megakaryoblasts in TEL–SYK mice. (c) Reticulin stain of BM and spleens of diseased TEL–SYK mice compared with controls display a strong fibrosis (II–III) in both organs (right panel). Bars, 50 μm.
© Copyright Policy - open-access
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4219468&req=5

fig3: TEL–SYK induces an AML with features of human APMF in mice. (a) Images from hematoxylin and eosin-stained BM, spleen and liver slides from control, SYKwt, TEL–SYK and ITK–SYK mice. ◂shows dysplastic and immature megakaryocytes /megakaryoblasts infiltrating BM, spleens and the liver of TEL–SYK mice. Bars, 50 μm. (b) Periodic acid–Schiff (PAS) stain of BM and spleens from control and TEL–SYK mice highlight the infiltrating megakaryoblasts in TEL–SYK mice. (c) Reticulin stain of BM and spleens of diseased TEL–SYK mice compared with controls display a strong fibrosis (II–III) in both organs (right panel). Bars, 50 μm.
Mentions: BM from TEL–SYK mice showed signs of multilineage dysplasia as seen in myelodysplastic syndrome, with hypoplasia of erythrocytes showing nuclear fragmentation, irregular nuclear contours and abnormal mitotic figures. Myelopoesis showed abnormal nuclear maturation with open chromatin, lobulated nuclei and hypogranulation. Immature megakaryocytes/megakaryoblasts were strongly increased reaching up to 50% of total cell counts and partially displayed multiple separated nuclei or unlobulated nuclei as well as micromegakaryocytes (Figure 3a, Supplementary Figure S7). Megakaryocytes were mainly periodic acid–Schiff stain positive (Figure 2b) and were organized in clusters. The immature megakaryoblasts in the BM were phenotypically identical with blasts seen in the peripheral blood. Reticulin staining showed a grade 2–3 myelofibrosis, at least partially explaining the reduced total cell counts in TEL–SYK mice (Figure 3c, Supplementary Figure S7). TEL–SYK spleens had lost their normal follicular architecture, were strongly fibrotic and were infiltrated with myeloid cells, predominantly consisting of mature granulocytes, dysplastic erythrocytes and clusters of dysplastic and immature megakaryocytes (Figure 3c). The same cell types also infiltrated the liver (Figure 3a). Taken together and according to the Bethesda classification of nonlymphoid hematopoietic neoplasms in mice44 (myeloid disorders), the TEL–SYK phenotype in the majority of mice can be classified as AML with features of human acute panmyelosis with myelofibrosis (APMF). Due to the frequent MDS features, we also have to consider the diagnosis of a myelodysplastic syndrome with features of human refractory anemia with excess blasts and fibrosis (RAEB-F) and at least one mouse, with more than 50% megakaryoblasts in the BM can be diagnosed as megakaryocytic leukemia.

Bottom Line: LKS cells were reduced and all subsets (LT/ST/MPP) showed reduced proliferation rates.SYK inhibitor treatment (R788) of diseased TEL-SYK mice reduced leukocytosis, spleen and liver infiltration, enhanced the hematocrit and prolonged survival time, but could not significantly reduce myelofibrosis.Stat5 was identified as a major downstream mediator of TEL-SYK in vitro as well as in vivo.

View Article: PubMed Central - PubMed

Affiliation: 1] Department of Hematology/Oncology, University Medical Center Freiburg, Freiburg, Germany [2] University of Freiburg, Schaenzlestrasse 1, Freiburg, Germany.

ABSTRACT
The spleen tyrosine kinase (SYK) was identified as an oncogenic driver in a broad spectrum of hematologic malignancies. The in vivo comparison of three SYK containing oncogenes, SYK(wt), TEL-SYK and IL-2-inducible T-cell kinase (ITK)-SYK revealed a general myeloexpansion and the establishment of three different hematologic (pre)diseases. SYK(wt) enhanced the myeloid and T-cell compartment, without leukemia/lymphoma development. ITK-SYK caused lethal T-cell lymphomas and the cytoplasmic TEL-SYK fusion induced an acute panmyelosis with myelofibrosis-type acute myeloid leukemia (AML) with up to 50% immature megakaryoblasts infiltrating bone marrow, spleen and liver, additional MPN features (myelofibrosis and granulocyte expansion) and MDS stigmata with megakaryocytic and erythroid dysplasia. LKS cells were reduced and all subsets (LT/ST/MPP) showed reduced proliferation rates. SYK inhibitor treatment (R788) of diseased TEL-SYK mice reduced leukocytosis, spleen and liver infiltration, enhanced the hematocrit and prolonged survival time, but could not significantly reduce myelofibrosis. Stat5 was identified as a major downstream mediator of TEL-SYK in vitro as well as in vivo. Consequently, targeted deletion of Stat5 in vivo completely abrogated TEL-SYK-induced AML and myelofibrosis development, proving Stat5 as a major driver of SYK-induced transformation. Our experiments highlight the important role of SYK in AML and myelofibrosis and prove SYK and STAT5 inhibitors as potent treatment options for those diseases.

Show MeSH
Related in: MedlinePlus