Trisomy 10 and acute myeloid leukemia

Secondary acute myelogenous leukemia (AML) with trisomy 10 and del(9q) following precursor B-cell acute lymphoblastic leukemia (ALL) with a hyperdiploid karyotype

Acute myelogenous leukemia (AML) secondary to acute lymphoblastic leukemia (ALL) in children is uncommon and usually occurs within 10 years of completing therapy for ALL. A variety of recurrent cytogenetic abnormalities have been described, suggesting significant biological heterogeneity. We report a case of highly refractory secondary AML with trisomy 10 and del(9q) occurring in an adolescent female 12 years after she was treated successfully for precursor B-cell ALL with chemotherapy only.

Differential cytogenomics and miRNA signature of the Acute Myeloid Leukaemia Kasumi-1 cell line CD34+38- compartment

The t(8;21) Acute Myeloid Leukaemia (AML) Kasumi-1 cell line with N822K KIT mutation, is a model system for leukemogenesis. As AML initiating cells reside in the CD34(+)CD38(-) fraction, we addressed the refined cytogenomic characterization and miRNA expression of Kasumi-1 cell line and its FACS-sorted subpopulations focussing on this compartment. By conventional cytogenetics, Spectral-Karyotyping and array-CGH the cytogenomic profile of Kasumi-1 cells evidenced only subtle regions differentially represented in CD34(+)CD38(-) cells. Expression profiling by a miRNA platform showed a set of miRNA differentially expressed in paired subpopulations and the signature of miR-584 and miR-182 upregulation in the CD34(+)CD38(-) fraction.

Hyperostosis - an unusual radiographic presentation of Myelodysplastic Syndrome transformed to Acute Myeloid Leukemia

Acute myeloid leukemia (AML) is also referred to non-lymphocytic leukemia in the literature. It comprises about 15% of the childhood leukemia. There are multiple subtypes of AML from M0-M7 with approximately 45% of the cases being M0-M2 and the remaining subtypes being rare. The definitive diagnosis relies on bone marrow biopsy showing bone marrow infiltration with leukemic cells. We describe a rare radiographic presentation of myelodysplastic syndrome (MDS) transformed to AML in an 8 month old boy who presented with a orbital wall fracture, periosteal reaction, and mixed lytic and sclerotic lesions.

Direct evidence for cooperating genetic events in the leukemic transformation of normal human hematopoietic cells

Although genetic abnormalities associated with hematological malignancies are readily identified, the natural history of human leukemia cannot be observed because initiating and subsequent transforming events occur before clinical presentation. Furthermore, it has not been possible to study leukemogenesis in vitro as normal human cells do not spontaneously transform. Thus, the nature and sequence of genetic changes required to convert human hematopoietic cells into leukemia cells have never been directly examined. We have developed a system where the first step in the leukemogenic process is an engineered disruption of differentiation and self-renewal due to expression of the TLS-ERG oncogene, followed in some cases by overexpression of hTERT. In two of 13 experiments, transduced cells underwent step-wise transformation and immortalization through spontaneous acquisition of additional changes. The acquired karyotypic abnormalities and alterations including upregulation of Bmi-1 and telomerase all occur in acute myeloid leukemia (AML), establishing the relevance of this system. One resultant cell line studied in depth exhibits cellular properties characteristic of AML, notably a hierarchical organization initiated by leukemic stem cells that differentiate abnormally. These findings provide direct evidence for multiple cooperating events in human leukemogenesis, and provide a foundation for studying the genetic changes that occur during leukemic initiation and progression.

[Chromosomal abnormalities in acute myeloid leukaemias]

Cytogenetic studies of acute myeloid leukaemias reveal non-random chromosomal abnormalities in 50-70% of karyotypes. Some are correlated with morphological and immunological parameters and constitute a prognostic factor independent of the other factors of risk: favourable for acute leukaemias myeloid with translocations t(8;21), t(15;17) and inversion or translocation of the chromosome 16, inv(16)/t(16;16), poor with deletion of the long arm of chromosome 5 del(5q), rearrangement of the 11q23 region and complex karyotypes. The distribution of the anomalies depends on the age: 11q23 and t(8;21) more frequent for the child, del(5q) and complex anomalies more frequent for the adult. The karyotypes are essential for the diagnosis, the follow-up of the patients and the evaluation of the relapse. It plays a fundamental part in the detection of new genes and their partners implied in the leucemogenese. The knowledge of their function is essential to open new therapeutic ways.