Overview. Cytogenetic analysis in haematology

Identification ofNUP98 abnormalities in acute leukemia:JARID1A (12p13) as a new partner gene

Chromosome rearrangements are found in many acute leukemias. As a result, genes at the breakpoints can be disrupted, forming fusion genes. One of the genes involved in several chromosome aberrations in hematological malignancies is NUP98 (11p15). As NUP98 is close to the 11p telomere, small translocations might easily be missed. Using a NUP98-specific split-signal fluorescence in situ hybridization (FISH) probe combination, we analyzed 84 patients with acute myeloid leukemia (AML), acute lymphoblastic leukemia, or myelodysplastic syndrome with either normal karyotypes or 11p abnormalities to investigate whether there are unidentified 11p15 rearrangements. Neither NUP98 translocations nor deletions were identified in cases with normal karyotypes, indicating these aberrations may be very rare in this group. However, NUP98 deletions were observed in four cases with unbalanced 11p aberrations, indicating that the breakpoint is centromeric of NUP98. Rearrangements of NUP98 were identified in two patients, both showing 11p abnormalities in the diagnostic karyotype: a t(4;11)(q1?3;p15) with expression of the NUP98-RAP1GDS1 fusion product detected in a 60-year-old woman with AML-M0, and an add(11)(p15) with a der(21)t(11;21)(p15;p13) observed cytogenetically in a 1-year-old boy with AML-M7. JARID1A was identified as the fusion partner of NUP98 using 3' RACE, RT-PCR, and FISH. JARID1A, at 12p13, codes for retinoblastoma binding protein 2, a protein implicated in transcriptional regulation. This is the first report of JARID1A as a partner gene in leukemia.

Adult acute myeloid leukaemia

The curability of acute myeloid leukaemia (AML) in a fraction of adult patients was demonstrated a long time ago. Currently, the probability of cure is consistently above fifty per cent in patients with de novo disease expressing favourable-risk associated cytogenetic features. Even better, the cure rate exceeds 75% in the acute promyelocytic subtype since the introduction of retinoic acid-containing regimens. In the meantime, continuing progress in supportive care systems and stem cell transplant procedures is making myeloablative therapies, when needed, somewhat less toxic-and thereby more effective-than in the recent past. Therefore, evidence is accumulating to indicate an improved therapeutic trend over the years, with the notable exception of older (>55 years) patients with adverse-risk chromosomal aberrations and/or leukemia secondary to myelodysplasia or prior cancer-related chemotherapy and/or radiotherapy. This review conveys the many facets of this progress, focusing on diagnostic subsets, risk classes, newer biological issues and conventional as well as innovative therapeutic interventions with or without autologous/allogeneic stem cell transplantation.

Chromosomal abnormalities and DNA image cytometry of haematological neoplasms in fine needle aspirates of lymph nodes

The current diagnostics of haematological neoplasms along with morphological analysis, immunophenotyping and molecular analysis inevitably includes cytogenetic analysis. In this work the possibility of cytomorphological subclassification of haematological neoplasms from lymph node fine needle aspirates was examined without depending upon the referential histological diagnosis and cytogenetic analysis. In addition, the feasibility of cytogenetic analysis of the material obtained by lymph node fine needle aspiration (FNA) was examined. By analysing the findings of cytogenetic analysis and DNA image cytometry, it was decided to examine the possibility of comparing the findings and supplementing diagnostic possibilities of these methods. In 15 cases cytological diagnoses and cytogenetic analysis of haematological neoplasms were performed on the material obtained by lymph node FNA. In 12 of 15 cases histological diagnosis was made separately. A good cytohistological correlation was available in 9 of 12 cases (75%). Cytomorphological diagnoses in 10 of 15 cases (76%) were confirmed by the finding of a specific chromosomal translocation. In two cases cytological diagnosis did not correlate with the histological diagnosis and was confirmed only with specific chromosomal translocations. The lymphocytes obtained by lymph node FNA were adequate material for cytogenetic analysis - in 15 of 18 (83%) cases mitoses in cell cultures were obtained. In 13 of 15 (87%) cases clonal chromosomal abnormalities were detected, whereas in 2 of 15 (13%) cases a normal karyotype was found. DNA image cytometry was performed on nine samples, whereas in six samples the material was not sufficient. Although a small number of samples was analysed in the cases with identical cytomorphological diagnoses, the analysed histograms regarding the DNA index values showed heterogeneity. In conclusion, a cell culture sampled by FNA of lymph nodes is an adequate method for the chromosomal analysis. The specific cytogenetic abnormality associated with cytological diagnosis provides an opportunity to make a definitive diagnosis and provides a powerful approach when reference diagnosis on biopsy material cannot be obtained.

Reovirus therapy of lymphoid malignancies

Reoviruses infect cells that manifest an activated Ras-signaling pathway, and have been shown to effectively destroy many different types of neoplastic cells, including those derived from brain, breast, colon, ovaries, and prostate. In this study, we investigated the reovirus as a potential therapeutic agent against lymphoid malignancies. A total of 9 lymphoid cell lines and 27 primary human lymphoid malignancies, as well as normal lymphocytes and hematopoietic stem/progenitor cells, were tested for susceptibility to reovirus infection. For in vitro studies, the cells were challenged with reovirus (serotype 3 Dearing), and viral infection was assessed by cytopathic effects, viability, viral protein synthesis, and progeny virus production. We present evidence of efficient reovirus infection and cell lysis in the diffuse large B-cell lymphoma cell lines and Burkitt lymphoma cell lines Raji and CA46 but not Daudi, Ramos, or ST486. Moreover, when Raji and Daudi cell lines were grown subcutaneously in severe combined immunodeficient/nonobese diabetic (SCID/NOD) mice and subsequently injected with reovirus intratumorally or intravenously, significant regression was observed in the Raji-induced, but not the Daudi-induced, tumors, which is consistent with the in vitro results. Susceptibility to reovirus infection was also detected in 21 of the 27 primary lymphoid neoplasias tested but not in the normal lymphocytes or hematopoietic stem/progenitor cells. Our results suggest that reovirus may be an effective agent against several types of human lymphoid malignancies.