Atsushi Wakita

MUM1/IRF4 expression as a frequent event in mature lymphoid malignancies.

MUM1/IRF4 is a myeloma-associated oncogene transcriptionally activated as a result of t(6;14)(p25,q32) chromosomal translocation and by virtue of its juxtaposition to the immunoglobulin heavy chain gene (IgH) locus. When this oncogene becomes non-functional, no activated B/T lymphocytes and Ig secreting plasma cells are observed, suggesting that MUM1/IRF4 is crucial for lymphoid development. Its expression was analyzed in both reactive lymphoid and lymphoma tissues by means of an immunohistochemical technique using specific goat antiserum against MUM1/IRF4. This analysis detected a 50 kDa MUM1product whose localization was restricted to the nuclei of the lymphocytes. The MUM1+ cells in reactive lymph nodes were found to consist of plasma cells and a small fraction (approximately 7.9%) of B cells harboring CD20+CD38+, which were located in the light zone of the germinal center. MUM1 expression in peripheral blood B/T lymphocytes was upregulated by mitogenic stimuli, suggesting that MUM1 positivity represents the activated state of the B/T cells. In B cell non-Hodgkins lymphoma (NHL), MUM1 expression was observed in 73.2% (30/41) of diffuse large B cell lymphoma (DLBCL), 20% (1/5) of marginal zone lymphoma (MZL) and 43% (3/7) of small lymphocytic lymphoma (SLL) cases, whereas it was not seen in any cases of mantle cell lymphoma (MCL) or follicle center lymphoma (FCL). Also, MUM1 was stained at high intensity in various types of T cell lymphomas including adult T cell leukemia/lymphoma (ATL/L) and anaplastic large cell lymphoma (ALCL) and in the majority of Hodgkins diseases. Our results suggest that a major proportion of lymphomas comprise either physiologically or aberrantly activated neoplastic lymphocytes expressing the MUM1 protein.

Ectopic Expression of MAFB Gene in Human Myeloma Cells Carrying (14;20)(q32;q11) Chromosomal Translocations

Chromosome 14q+, which represents a chromosomal rearrangement involving the immunoglobulin heavy chain gene (IgH) locus, is a genetic hallmark of human multiple myeloma (MM). Here, we report the identification of (14;20)(q32;qll) chromosomal translocations found in MM cells. Double color fluorescence in situ hybridization analyses pinpointed the breakpoints at the 20qll locus in two MM cell lines within a length of at most 680 kb between the KIAA0823 and MAFB gene loci. Among the transcribed sequences in the vicinity of the breakpoints, an ectopic expression of the MAFB gene, which is located at 450‐680 kb telomeric to one of the breakpoints and encodes a member of the MAF family basic region/leucine zipper transcription factor, was demonstrated to be associated with t(14;20). This finding, together with that of a previous study describing its transforming activity, suggests that the MAFB gene may be one of the targets deregulated by regulatory elements of the IgH gene as a result of t(14;20).

Detection of MUM1/IRF4-IgH fusion in multiple myeloma

MUM1 (multiple myeloma oncogene 1)/IRF4 (interferon regulatory factor 4) gene has been identified as an oncogene transcriptionally activated by t(6;14)(p25;q32) chromosomal translocation in multiple myeloma (MM). The significance of this alteration in MM remains unknown, as it is not detectable by means of conventional cytogenetic analysis. To address this issue, we established diagnostic procedures based on pulsed-field gel electrophoresis (PFGE) analysis and double color fluorescence in situ hybridization (DCFISH) using DNA probes derived from the MUM1 and the immunoglobulin heavy chain (IgH) gene loci. Among a panel of 17 MM cell lines, three (17.6%) showed fusions between these two loci, which resulted in the juxtaposition of the MUM1 to the IgH 3′ α-enhancer region by virtue of t(6;14) or insertion of the IgH sequences into the vicinity of the MUM1 gene and in the concomitant overexpression of the MUM1 mRNA. With similar results, fusions between MUM1 and IgH loci were observed by means of interphase DCFISH in eight (21.1%) out of the 38 MM cases, although no definite relationships between MUM1 status and specific clinical findings could be established.

MICROSATELLITE INSTABILITY AS A POTENTIAL MARKER FOR POOR PROGNOSIS IN ADULT T CELL LEUKEMIA/LYMPHOMA

Microsatellite instability (MSI) represents a replication error resulting from the dysfunction of mismatch repair gene products. In this study, MSI was analyzed in 18 patients with various subtypes of adult T cell leukemia/lymphoma (ATL/L). Using six different microsatellite loci, we defined MSI as positive when replication errors were observed in at least two loci. The MSI was positive in four cases (22.2%)with acute type ATL, who tended to show more prognostically unfavorable factors and shorter overall survival. These results suggest that genomic instability may be associated with tumor progression rather than the development of ATL/L itself. In addition, the presence of the MSI at initial presentation could appear to warrant consideration as an additional prognostically unfavorable factor.

Aplastic anaemia with 13q–: a benign subset of bone marrow failure responsive to immunosuppressive therapy

Summary. In an attempt to determine the pathological significance of a long arm deletion of chromosome 13 (13q–) in bone marrow failure syndrome, we reviewed the clinical records of nine patients who were initially diagnosed with aplastic anaemia due to bone marrow hypoplasia without dysplasia. Six patients responded to immunosuppressive therapy and the other three improved with steroids. None of the patients developed acute leukaemia (follow up: 54–129 months) and the estimated 5‐year survival was 78%. These findings indicate that pancytopenia with 13q– represents bone marrow failure of a benign nature, similar to aplastic anaemia without karyotypic abnormalities, rather than preleukaemia.

Successful Treatment of Nasal T-Cell Lymphoma With a Combination of Local Irradiation and High-Dose Chemotherapy

Nasal natural killer (NK)/T-cell lymphoma is characterized by an aggressive clinical course and poor prognosis. The term “NK/T-cell” lymphoma includes both the NK-cell type and the T-cell type, which are classified by immunophenotyping and according to T-cell receptor (TCR) rearrangement. In addition, CD56+ T-cell lymphoma is defined as NK-like T-cell lymphoma. This report concerns a 54-year-old woman with nasal T-cell lymphoma. Its phenotype showed pure T-cell type with CD3+, CD56—, and TCR+ accompanied by Epstein-Barr virus infection. Although the lesions were localized in the nasal mucosa and facial skin (stage IE), local irradiation could not achieve complete remission (CR). We then administered 5 courses of CHOP (cyclophosphamide, doxorubicin, vincristine, and prednisolone) regimen followed by high-dose chemotherapy with an autologous peripheral blood stem cell transplantation. This therapy resulted in CR. Our results suggest that this lymphoma subtype may be cured by means of intensive treatment soon after diagnosis.

Twenty Years’ Experience in Allogeneic Hematopoietic Stem Cell Transplantation for Philadelphia Chromosome—Positive Acute Lymphoblastic Leukemia in the Nagoya Blood and Marrow Transplantation Group

Between October 1981 and December 2000, 46 patients with Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ ALL) underwent allogeneic hematopoietic stem cell transplantation (HSCT) in the Nagoya Blood and Marrow Transplantation Group. The median age was 28.5 years (range, 4–51 years). All but one patient achieved engraftment. Grade II-to-IV acute graft-versus-host disease (GVHD) developed in 32.5% of patients, and chronic GVHD developed in 40.5%. The incidences of relapse and treatment-related mortality (TRM) at 5 years were 65% and 26%, respectively. The estimated overall survival rate at 5 years was 23%. Univariate analysis showed that improved disease-free survival (DFS) was independently associated with complete remission (CR) at transplantation (39%), compared with non-CR (8%) (P =.023). Non-CR at transplantation was associated with a higher risk of relapse. Donor type, acute GVHD, and time from diagnosis to HSCT all had a significant effect on TRM. In a multivariate analysis, 9 months or more from diagnosis to HSCT was the only variable statistically significant for DFS (relative risk, 3.22; P =.01). This study demonstrates that allogeneic HSCT cures a significant population of patients with Ph+ ALL. Relapse is the major obstacle limiting the success of HSCT. Early transplantation during CR from donors, including unrelated persons or mismatched relatives, may offer improved long-term DFS.

Lymphoid blastic crisis of chronic myelogenous leukaemia with inv(16)(p13;q22).

We report a case of chronic myelogeneous leukaemia (CML) in B-lineage lymphoid blastic crisis (BC) having chromosome abnormality, inv(16)(p13;q22) in addition to Philadelphia chromosome, in 20/20 marrow metaphase. Inv(16)(p13;q22) was not observed in cells of chronic phase or accelerate phase. Abnormalities of chromosome 16, including inv(16)(p13;q22), del(16)(q22) and t(16;16)(p13;q22), have been reported mostly in acute myelomonocytic leukaemia (AML), (FAB M4-Eo), and some in CML-BC and myelodysplastic syndrome (MDS) cases. Most of the cases showed increase of myelomonocytic components and abnormal eosinophils with dysplastic granules in the bone marrow (BM). However, our case was diagnosed as lymphoid BC without increase of myelomonocytic components, although some abnormal eosinophilia was seen. To date, lymphoid BC of CML having inv(16)(p13;q22) abnormality has not been reported. The case presented here could be a clue to understand the pathophysiology of inv(16)(p13;q22) leukaemia.

Microsatellite instability is rare in the clinical course of myelodysplastic syndrome studied with DNA from fresh and paraffin-embedded tissues

Abstract Microsatellite instability (MSI) has been reported to occur in various types of malignant neoplasms. We performed a polymerase-chain-reaction-based assay for MSI between the initial and the most recently available (“latest”) samples from 23 patients with myelodysplastic syndrome (MDS). Of these patients, 15 were informative at more than three microsatellite loci. Seven patients showed an increase in leukemic cells while 8 patients did not during the interval between the two analyses. Only 1 of the patients, who had refractory anemia with excess blasts, which changed to acute myelogenous leukemia, showed microsatellite alteration at the analysis times. Among all 23 patients, two alterations were detected in the 42 informative paired samples that showed an increase in leukemic cells (4.8%), while none was detected in the 59 paired samples without such an increase. In total, therefore only two alterations were detected among 101 informative paired samples (2%). This indicates that MSI is rare in the clinical course of MDS irrespective of disease status, and is consequently not a critical genetic event for disease progression in most MDS patients.

Detection of bcr/abl fusion transcripts by semiquantitative multiplex RT-PCR combined with a colormetric assay in Ph positive leukemia

We studied the feasibility of the clinical application of a new bcr/abl analysis system, C-TRAK t(9;22), consisting of a multiplex RT-PCR and a colormetric assay. With this system, bcr/abl transcripts could be detected in all of 24 cytogenetic Philadelphia chromosome (Ph) positive leukemia patients and in none of eight Ph negative patients. Multiple bcr/abl transcripts could be detected in three of the 24 Ph positive patients, the fusion of bcr exon 1 to abl exon 2 (e1a2 junction) dominated that of bcr exon 13 to abl exon 2 (b2a2 junction) in two cases and that of bcr exon 14 to abl exon 2 (b3a2 junction) and b2a2 dominated e1a2 in one case. This system was sensitive enough to be able to detect even one bcr/abl transcript-producing cell in 50000 bcr/abl negative background cells, thus making it suitable for semiquantitative evaluation. Minimal residual disease (MRD) was monitored in one Ph positive leukemia patient who underwent allogenic bone marrow transplantation (allo-BMT). After allo-BMT, a weak positivity of the bcr/abl transcript continued with no clinical relapse; this result was consistent with that of a conventional nested PCR assay using ethidium bromide staining. Including all the procedures for RNA extraction, it took only about 10 h to detect the bcr/abl transcripts. Our findings indicate that this bcr/abl analysis system provides a quick and sensitive method for screening bcr/abl transcripts and possibly for monitoring MRD in Ph positive leukemia patients.