Ultrastructural and ultracytochemical differences between megakaryoblastic leukemia in children and adults. Analysis of 49 patients

Integrated differential transcriptome maps of Acute Megakaryoblastic Leukemia (AMKL) in children with or without Down Syndrome (DS)

BACKGROUND

The incidence of Acute Megakaryoblastic Leukemia (AMKL) is 500-fold higher in children with Down Syndrome (DS) compared with non-DS children, but the relevance of trisomy 21 as a specific background of AMKL in DS is still an open issue. Several Authors have determined gene expression profiles by microarray analysis in DS and/or non-DS AMKL. Due to the rarity of AMKL, these studies were typically limited to a small group of samples.

METHODS

We generated integrated quantitative transcriptome maps by systematic meta-analysis from any available gene expression profile dataset related to AMKL in pediatric age. This task has been accomplished using a tool recently described by us for the generation and the analysis of quantitative transcriptome maps, TRAM (Transcriptome Mapper), which allows effective integration of data obtained from different experimenters, experimental platforms and data sources. This allowed us to explore gene expression changes involved in transition from normal megakaryocytes (MK, n=19) to DS (n=43) or non-DS (n=45) AMKL blasts, including the analysis of Transient Myeloproliferative Disorder (TMD, n=20), a pre-leukemia condition.

RESULTS

We propose a biological model of the transcriptome depicting progressive changes from MK to TMD and then to DS AMKL. The data indicate the repression of genes involved in MK differentiation, in particular the cluster on chromosome 4 including PF4 (platelet factor 4) and PPBP (pro-platelet basic protein); the gene for the mitogen-activated protein kinase MAP3K10 and the thrombopoietin receptor gene MPL. Moreover, comparing both DS and non-DS AMKL with MK, we identified three potential clinical markers of progression to AMKL: TMEM241 (transmembrane protein 241) was the most over-expressed single gene, while APOC2 (apolipoprotein C-II) and ZNF587B (zinc finger protein 587B) appear to be the most discriminant markers of progression, specifically to DS AMKL. Finally, the chromosome 21 (chr21) genes resulted to be the most over-expressed in DS and non-DS AMKL, as well as in TMD, pointing out a key role of chr21 genes in differentiating AMKL from MK.

CONCLUSIONS

Our study presents an integrated original model of the DS AMLK transcriptome, providing the identification of genes relevant for its pathophysiology which can potentially be new clinical markers.

Clinico-haematological profile of acute megakaryoblastic leukaemia: report of five cases

Acute megakaryoblastic leukemia (AMKL) is a rare subtype of acute myeloid leukemia. Although known as a distinct entity for a very long time, because of lack of distinct clinical features and morphological criteria, it is difficult to diagnose this variant correctly. We herein present the clinical, morphological, cytochemical, and immunocytochemical features of five cases of AMKL. Certain morphological features such as presence of abnormal platelet count, giant platelets, and cytoplasmic blebbing in blasts were found to be important pointers towards the diagnosis. However, none of the features were found to be consistent and thus morphological diagnosis has to be confirmed by cytochemistry and immunocytochemistry.

Paraplegia as the presenting manifestation of extramedullary megakaryoblastic transformation of previously undiagnosed chronic myelogenous leukemia

Extramedullary tumors, also known as granulocytic sarcomas (GS), occur most frequently in acute myelogenous leukemia (AML). They may signal the onset of the accelerated phase of chronic myelogenous leukemia (CML) or the blastic transformation of a myeloproliferative disorder. Occasionally, a GS may be the presenting sign of undiagnosed AML, and rarely the presenting sign of undiagnosed CML or aleukemic leukemia. Paraplegia due to a spinal cord GS is an extremely rare presentation of undiagnosed leukemia. This is the first case report of paraplegia as the presenting manifestation of extramedullary megakaryoblastic transformation of previously undiagnosed CML. A 53-year-old woman reported back pain for 6 days, rapidly progressing to paraplegia. Physical examination noted a large abdominal mass and flaccid paralysis in both lower extremities. Spinal MRI revealed a T4-T6 vertebral mass causing spinal stenosis and cord compression. Tumor debulking and laminectomy were performed emergently. The tumor consisted of noncohesive blast cells. The CBC revealed a leukocyte count of 238,300/microl and a differential consistent with CML. Reexamination of the patient found that the abdominal mass was a giant spleen. Further immunohistochemical studies of the tumor were consistent with extramedullary acute megakaryoblastic blast transformation of CML. Although extramedullary blast crises herald the accelerated phases in approximately 10% of CML cases, megakaryoblastic blast transformation of CML accounts for less than 3% of these cases. The combination of acute paraplegia and megakaryoblastic transformation in a previously undiagnosed patient with CML is extremely rare and may pose a diagnostic dilemma.

Establishment and characterization of a new erythroblastic leukemia cell line, EEB: phosphatidylglucoside-mediated erythroid differentiation and apoptosis

A new erythroblastic leukemia cell line (EEB) was established from a patient with early erythroblastic leukemia. The cells had features of immature erythroblasts, including an agranular basophilic cytoplasm and CD36, CD71, CD175s (sialyl-Tn) and CD235a (glycophorin A) expression without CD41 expression, myeloperoxidase activity and platelet-peroxidase activity. The cells were confirmed to be of the erythroid lineage based on expression of the gamma-globin message. They were induced to differentiate into benzidine-positive cells by hemin and delta-amino levulinic acid (delta-ALA). An analysis of cell membrane lipids showed that EEB cells contain a type of glycerolipid, phosphatidylglucose (PhGlc), but not unbranched type 2 chains, i antigens. GL-7 which is a recombinant Fab fragment of GL-2 and binds to PhGlc, induced production of hemoglobin F (HbF) associated with accumulation of the gamma-globin (gamma-globin) message in EEB cells. The GL-7-mediated erythroid differentiation was associated with apoptosis. These results suggest that direct signaling to PhGlc mediates erythroid differentiation and apoptosis in EEB cells.

Recombinant activated factor VII for severe gastrointestinal bleeding after chemotherapy in an infant with acute megakaryoblastic leukemia

Recombinant activated factor VII (rFVIIa) is a major alternative for management of hemophiliac patients with inhibitors. Additionally, it has been used off-label for the treatment of massive life-threatening hemorrhage associated with various bleeding situations. Herein, we describe a 16-month-old boy with acute megakaryoblastic leukemia and severe intractable gastrointestinal bleeding controlled by rFVIIa. rFVIIa should be considered as a novel treatment alternative in severe bleeding conditions including leukemias that may have hemostatic defects and platelet dysfunction.

Megakaryocytic blast crisis as a first presentation of chronic myeloid leukemia

Acute megakaryocytic leukemia (AmegL) corresponds to 5.0-10.0% of all acute myeloid leukemias (AML). Blast crisis as the first presentation of chronic myeloid leukemia (CML) accounts for 10.0% of all cases.

OBJECTIVE

We report a case of megakaryocytic blast crisis as the first presentation of CML.

CASE REPORT

A 25-yr-old-female with a 2-month history of dry cough and a large, non-tender splenomegaly was found to have a hemoglobin concentration of 10.5 g/dL, a hematocritof 33.0%, a white blood cell count (WBC) of 11.4 x 106 L with 38% small blasts, eosinophilia of 5%, basophilia of 8%, and a platelet count of 580 x 109 L. Bone marrow aspiration revealed 24% of blast cells with cytoplasmatic blebs and hyperplastic megakaryocytic lineage with dysplasia. Cytochemical stains were all negative, immunophenotyping studies showed CD41 and CD61 positivity in blast cells. Bone marrow biopsy showed grade II fibrosis. Karyotype revealed 46, XX, t(9,22) (q34.1;q11.2)[20] and the reverse-transcriptase-PCR (RT-PCR) gave rise a product with a size corresponding to the 210 kDa protein (p210). No matched donor was found. After induction therapy 5.9% of blast cells persisted. The patient received Imatinib Mesylate and is doing well after a 12-month follow-up.

DISCUSSION

AmegL as the first presentation of CML is a rare and often fatal event. Some characteristics point towards the diagnosis of a blast crisis instead of AmegL de novo with t(9,22).

In Vitro Development of Erythroid and Megakaryocytic Cells From a UT-7 Subline, UT-7/GM

UT-7 is a human megakaryoblastic leukemia cell line with absolute dependence on interleukin-3, granulocyte-macrophage colony-stimulating factor (GM-CSF ), or erythropoietin (EPO) for growth and survival. We isolated a novel subline, UT-7/GM after long-term culture of UT-7 with GM-CSF. The hemoglobin concentration and γ-globin and EPO-receptor mRNA levels were significantly higher in EPO-treated UT-7/GM cells than in untreated cells. In contrast, the platelet factor 4 and glycoprotein IIb mRNA levels were much higher in thrombopoietin (TPO)-treated UT-7/GM cells than in untreated cells. Some TPO-treated cells had morphologically mature megakaryocytic characteristics such as a developed demarcation membrane in the cytoplasm and multilobular nuclei. These findings indicate that UT-7/GM is a bipotential cell line that can be induced to differentiate into erythroid and megakaryocytic lineages by EPO and TPO, respectively. Moreover, a minority of UT-7/GM cells acquired a high hemoglobin concentration by treatment with TPO, suggesting that TPO in part induced the erythroid differentiation of the UT-7/GM cells. Interestingly, GM-CSF inhibited the EPO- or TPO-induced erythroid differentiation and the TPO-induced megakaryocytic differentiation of UT-7/GM cells. These results support the hypothesis that cytokines influence the programming of gene expression required for lineage commitment or differentiation.

Molecular analysis of minimally differentiated acute myeloid leukemia with chromosome 16 inversion

We report a 3-year-old girl with minimally differentiated acute myeloid leukemia and chromosome 16 inversion (inv 16). Inv 16 is generally associated with acute myelomonocytic leukemia with dysplastic eosinophils in the bone marrow (AML-M4Eo). Recently, molecular analysis showed that a fusion gene is generated by this inversion between the CBFB gene on the q arm and the MYH11 gene on the p arm. Using reverse transcriptase-polymerase chain reaction analysis, we tried to detect CBFB/MYH11 chimeric mRNA in blasts from our patients, however, were unable to detect any chimeric mRNA in the blasts: The absence of CBFB/MYH11 transcripts in this case suggests that rare chimeric products might be formed as a result of inv 16 that could not be detected by the primer sets used in this study. Another possibility is that different genes are rearranged on the chromosome 16 with the inv 16. More detailed molecular analysis of this case might be necessary in order to elucidate these possibility. Analyzing leukemias with inv 16 which do not have a typical CBFB/MYH11 chimeric mRNA might lead to understanding an alternative pathogenesis for acute leukemia with inv 16.

Erythroblastic and/or megakaryoblastic leukemia in Down syndrome: treatment with low-dose arabinosyl cytosine

PURPOSE

We report here the clinical response to low-dose arabinosyl cytosine (Ara-C) in seven children with Down syndrome (DS) and acute leukemia in which blast cells express markers of erythroid and/or megakaryoblastic lineages. Following an initial course of treatment with Ara-C, complete remission was obtained in all seven patients. Maintenance therapy with Ara-C was continued during complete remission. Four patients subsequently relapsed; the three others are disease-free. Based on these data, we suggest that when conventional therapy is contraindicated by associated malformations, low-dose Ara-C can be used for treating DS patients with erythroblastic or megakaryoblastic leukemia. The aim of this study was to assess the efficacy of low-dose Ara-C in treating megakaryoblastic and/or erythroblastic leukemia associated with DS.

PATIENTS AND METHODS

Seven patients with DS presented with leukemia in which blast cells displayed early markers of the erythroblastic and/or megakaryoblastic lineage. Low-dose subcutaneous Ara-C (10 mg/m2 two times per day) was given for 21 days as induction therapy, followed by a 5-10-day course each month for 2 years as a maintenance treatment.

RESULTS

Low-dose Ara-C treatment resulted in complete remission in all seven patients and in long-term disease-free survival in three patients.

CONCLUSION

In cases in which conventional chemotherapy is contraindicated, low-dose Ara-C should be considered as a therapeutic alternative for treatment of DS-associated erythroblastic or megakaryocytic leukemia.

Interleukins and colony stimulating factors in human myeloid leukemia cell lines

The present review has summarized the expression, production and effects of the human interleukins (IL) 1-11 and myelopoietic colony stimulating factors (CSF) in the established myeloid leukemia cell lines and in cells from patients with acute myeloid leukemia as well as the oncogene expression reported in these myeloid leukemia cell lines. The genetic dissection of leukemic myelopoiesis may provide new perspectives for the control of myeloid leukemias. Based on their expression of phenotypic markers (e.g., surface antigens, cytochemical staining, etc.), myeloid cell lines can be further subdivided into myelogenous, monocytic, erythroid and megakaryoblastic leukemia cell lines. Due to the close relationship of erythroid and megakaryoblastic progenitor cells and to the existence of a probably common precursor cell giving rise to these two different cell lineages, many megakaryoblastic cell lines express erythroid markers (e.g., expression of hemoglobin or glycophorin A) and conversely cell lines with a predominant erythroid profile might display megakaryoblastic features (e.g., platelets peroxidase or glycoproteins CD41, CD42b or CD61). The recent cloning of the specific cytokine: thrombopoietin (TPO) and its receptor generated a strong interest in these particular myeloid cell lines that are discussed in more detail in the present review. Both normal and leukemic megakaryocytopoiesis are stimulated by granulocyte-macrophage colony stimulating factor (GM-CSF), IL-3, GM-CSF/IL-3 fusion protein, IL-6, IL-11 and TPO but inhibited by IL-4, interferon-alpha (IFN-alpha) and IFN-gamma. Human megakaryoblastic leukemia cell lines have common biological features: high expression of the megakaryocytic specific antigen (CD41); high expression of early myeloid antigens (CD34, CD33 and CD13); constitutive expression of IL-6 and platelet-derived growth factor; a complex karyotype picture; expression of c-kit (the stem cell factor receptor); growth-dependency or -stimulation by IL-3 and/or GM-CSF; and in vivo tumorigenicity in mice associated with marked fibrosis. Whereas numerous chemical and biologic agents induce granulocytic and/or monocytic differentiation of myeloid leukemia cell lines, only a few agents including phorbol myristate acetate, vitamin D3, IFN-alpha, IL-6 and thrombin have been reported to induce megakaryocytic differentiation in the megakaryoblastic leukemia cells.

Characteristic biological features of human megakaryoblastic leukaemia cell lines

Both normal and leukaemic human megakaryocytopoiesis are stimulated by several cytokines, including stem cell factor, granulocyte-macrophage colony stimulating factor (GM-CSF), interleukin-3, GM-CSF/interleukin-3 fusion protein, interleukin-6, interleukin-11, basic fibroblast growth factor and thrombopoietin, but are inhibited by tumour necrosis factor-alpha, platelet factor 4, beta-thromboglobulin, thrombin, interleukin-4, interferon-alpha and interferon-gamma. Human megakaryoblastic leukaemia cell lines have common biological features, including high expression of the megakaryocytic specific antigen: CD41; high expression of the early myeloid antigens: CD34 and CD33; constitutive expression of interleukin-6 and platelet-derived growth factor; complex karyotype picture; expression of c-kit: the stem cell factor receptor; growth-dependency or -stimulation by stem cell factor, interleukin-3 and/or GM-CSF; megakaryoblastic differentiation by phorbol-myristate-acetate; and in vivo tumorigenicity in mice is associated with marked fibrosis. Only a few agents including phorbol-myristate-acetate; vitamin D3, interferon-alpha, interferon-beta 2, erythropoietin and thrombin have been reported to induce megakaryocytic differentiation in the human megakaryoblastic leukaemia cells.

Acute megakaryoblastic leukemia

In 1985 acute megakaryoblastic leukemia was included in the FAB classification system of hematological neoplasias with the designation of AML M7. It occurs in all age groups with two peaks in distribution. The one is in adults and the other in children 1 to 3 years of age especially in those with Down's syndrome. The diagnosis of AML M7 requires more than 30% of the nucleated bone marrow cells being megakaryoblasts. The more common types of AML MO-M6 have to be excluded by morphological and cytochemical analysis whereas immunology is needed to exclude ALL. The megakaryocytic nature of the leukemia has to be proven by ultrastructural demonstration of platelet peroxidase or by immunological demonstration of CD61, CD42, CD41 on the surface of the leukemic blasts. Megakaryocytic/megakaryoblastic leukemias show a wide morphologic spectrum. In some instance small cells dominate, clearly showing megakaryocytic differentiation with scant amounts of cytoplasm and with nuclei showing dense chromatin. On the other hand, there are cases with larger cells resembling ALL-L2 blasts with moderate amounts of rather basophilic cytoplasm which in some instances contain azurophilic granules. Cytoplasmic blebs and protrusions are the most prominent feature of many cases. The nuclei of these cells are round with more finely reticulated chromatin and with prominent nucleoli. The megakaryoblastic nature of these cells can be suggested by morphology. However, according to our experience there are cases of c-ALL with the very same morphologic picture. Consequently, immunologic phenotyping of these cases is necessary in any instance. Cytochemistry is of limited diagnostic value in megakaryoblastic leukemias. Usually it is used to exclude the more common types of leukemia.

Effect of recombinant human interferons in inducing differentiation of acute megakaryoblastic leukaemia blast cells

The effects of interferons (IFN)-alpha, beta 2 and -gamma in inducing megakaryocytic differentiation of blast cells from a patient with acute megakaryoblastic leukaemia (AMegL) was investigated in liquid suspension culture by the increase in CD41 and CD42b expressions using monoclonal antibodies in the APAAP technique. After six days of culture, the percentage of CD41 and CD42b positive cells increased in control cultures from 15.2% and 10.6% on day 0 to 32.0 +/- 4.3% and 22.1 +/- 2.5%, respectively. The addition of IFN-alpha significantly increased the number of CD41 and CD42b positive cells by about two to three fold compared to control cultures (p < 0.01) and by about four to six fold compared to day 0 (p < 0.001) Similarly, IFN-beta 2 induced a significant increase in CD41 and CD42b positive cells. On the other hand, IFN-gamma failed to increase the number of CD41 and CD42b positive cells in comparison to control cultures on day 6 and instead stimulated a significant increase in the number of monocytes/macrophages by about ten fold compared to control cultures in IFN-gamma-treated cultures (p < 0.001). The present results suggest that megakaryocytic differentiation of blast cells in AMegL could be induced by IFN-alpha and beta 2 and support a clinical role for them in the treatment of AMegL patients. Also, the present results showed that monocytic differentiation of blast cells in AMegL could be stimulated by IFN-gamma, supporting the multipotent stem or progenitor cell origin of the AMegL subtype of acute myelogenous leukaemia.

Ultrastructural investigation of DNA in megakaryoblastic leukemia by using osmium-ammine-B: comparison with several types of leukemia

Using DNA staining with highly stable osmium-ammine-B, the blasts of AMKL were observed under an electron microscope, in comparison with AML, ALL, CML-MK crisis and TMD. The DNA within the nucleus of the megakaryoblasts was observed as a high electron-density substance and tended to be uniformly dispersed within the nucleus. DNA, associated with nucleoli, could be roughly divided in four types based on the presence or absence of peri-nucleolar clumps and intra-nucleolar clumps. In cases of AMKL, we often observed a type that did not have peri-nucleolar DNA clumps but did have DNA flecks within the nucleoli. By analytical evaluation there were no differences among cells from several subtypes of megakaryocytic leukemia, such as AMKL in children with Down's syndrome, AMKL in children without Down's syndrome, AMKL in adults, and CML-MK crisis. The DNA distribution of TMD blasts, which were self-limited and not malignant, resembled that of AMKL blasts.