Akiko Sakashita

Novel MLL-CBP fusion transcript in therapy-related chronic myelomonocytic leukemia with a t(11;16) (q23;p13) chromosome translocation

CBP, which is located on 16p13 and encodes a transcriptional adaptor/coactivator protein, has been shown to fuse by the t(8;16)(p11;p13) translocation to MOZ on 8p11 in acute myeloid leukemia. We found a t(11;16)(q23;p13) in a child with therapy‐related chronic myelomonocytic leukemia. Subsequent reverse transcriptase‐polymerase chain reaction and direct sequencing analyses revealed the MLL‐CBP fusion transcript in CMML cells. Because 11q23 translocations involving MLL and t(8;16) involving MOZ and CBP have been reported in therapy‐related leukemias, both the MLL and CBP genes may be targets for topoisomerase II inhibitors. Accordingly, we believe that most t(11;16)‐associated leukemias may develop in patients who have been treated with cytotoxic chemotherapy for primary malignant diseases. Genes Chromosom. Cancer 20:60–63, 1997.

Disappearance of AML1-MTG8 (ETO) fusion transcript in acute myeloid leukaemia patients with t(8;21) in long-term remission

Summary. In a study of 23 patients with t(8;21)‐associated acute myeloid leukaemia the AML1‐MTG8 fusion transcript was present in the majority of serial samples obtained from 17 patients followed for up to 34 months after diagnosis, but was absent in samples from all six patients who had been in continuous complete remission for 61 months after allogeneic bone marrow transplantation (BMT), or for 52, 53, 123,182 and 198 months, respectively, after courses of intensive chemotherapy. Previous studies showed that the AML1‐MTG8 fusion transcript was present in most patients with this type of translocation in long‐term remission. Our results indicate that blood cells of patients with t(8;21) in remission of over 10 years may not show the AML1‐MTG8 fusion transcript, and that those of patients who have undergone allogeneic BMT or intensive chemotherapy may become fusion transcript‐negative much earlier. Our study suggests that leukaemic cells with the AML1‐MTG8 fusion transcript may survive for some time after courses of chemotherapy or BMT, but that they may eventually be eradicated by immunologic and other antileukaemic mechanisms.

The der(21)t(12;21) chromosome is always formed in a 12;21 translocation associated with childhood acute lymphoblastic leukaemia

We studied 116 patients (93 children and 23 adults) with acute lymphoblastic leukaemia (ALL) using fluorescence in situ hybridization (FISH) with the yeast artificial chromosome (YAC) clone, 964c10, which includes the recently described ETS‐like gene, TEL, on 12p13. FISH revealed that nine of the patients had a t(12;21), which had not been previously detected. The nine patients were all children, seven boys and two girls, aged 1–10 years (median 3 years), had an early B immunophenotype, and achieved complete remission, although two of them experienced haematological relapse. In addition to the t(12;21), FISH also revealed that three of the nine had a del(12p) in the other homolog of chromosome 12 or in the der(12) chromosome itself, and that two others had 12p translocations in the other chromosome 12 homolog. Although chromosomal rearrangements associated with the t(12;21) were heterogenous and complex, fusion of the sequences from chromosomes 12 and 21 on the der(21)t(12;21) chromosomes was consistent, suggesting that the TEL‐AML1 gene fusion on the der(21) chromosome may be critical in leukaemogenesis and that FISH or reverse transcriptase‐polymerase chain reaction (RT‐PCR) targeted to the chimaeric sequences on the der(21) will be most useful in detecting the t(12:21) or following a patient with the t(12;21), which is one of the most frequent chromosomal rearrangements in both Caucasian and Asian childhood ALL.

Mixed-lineage leukemia with t(10;11)(p13;q21): An analysis of AF10-CALM and CALM-AF10 fusion mRNAs and clinical features

A fusion transcript of AF10 and CALM was isolated recently from the U937 cell line with t(10;11)(p13;q21). We performed reverse transcription–polymerase chain reaction and sequencing analysis on the t(10;11) leukemia samples obtained from four patients and one cell line, and we identified reciprocal fusion transcripts of AF10 and CALM in all the samples. The fusion transcripts in the five samples showed four different breakpoints in AF10 and three different breakpoints in CALM. In addition, the fusion transcripts in one sample showed a nucleotide sequence deletion in AF10, and those in two samples showed a nucleotide sequence deletion in CALM; the deletions were thought to be caused by alternative splicing. The variety of breakpoints and splice sites in the two genes resulted in five different‐sized AF10‐CALM mRNAs and in four different‐sized CALM‐AF10 mRNAs. Clinical features of 11 patients, including 6 of our own and 5 reported by others, in whom the fusion of AF10 and CALM was identified, are characterized by young age of the patients, mixed‐lineage immunophenotype with coexpression of T‐cell and myeloid antigens, frequent occurrence of a mediastinal mass, and poor clinical outcome. Genes Chromosomes Cancer 25:33–39, 1999.

Granulocyte-colony Stimulating Factor and Retinoic Acid Cooperatively Induce Granulocytic Differentiation of Acute Promyelocytic Leukemia Cells in vitro

The interaction of granulocyte‐colony stimulating factor (G‐CSF) and retinoic acid (RA) in proliferation and differentiation of acute promyelocytic leukemia (APL) cells was examined. G‐CSF stimulated proliferation of APL cells at concentrations of 0.1 to 50 ng/ml in a dose dependent manner. More than 10−8M RA induced granulocytic differentiation of APL cells. Although G‐CSF induced lysozyme activities in APL cells, it alone did not induce terminal differentiation of APL cells. G‐CSF significantly enhanced the RA‐induced granulocytic differentiation of APL cells in vitro. Enhancement by G‐CSF was not due to the prolongation of survival of RA‐induced differentiated cells, but the differentiation‐inducing effects of G‐CSF might be evident only in the presence of RA. Since G‐CSF has a potential to induce the granulocytic differentiation of myeloid leukemia cells, G‐CSF in combination with RA may be applicable in differentiation induction therapy for some types of myeloid leukemia.

Minimal residual disease in acute monocytic leukemia patient with trisomy 11 and partial tandem duplication of MLL

We studied MLL rearrangements in five patients with myeloid hematologic malignancies with trisomy 11. Two had acute monocytic leukemia (AMoL), one had chronic myelomonocytic leukemia, one had refractory anemia, and the other had juvenile chronic myelogenous leukemia. Only one patient, a 15-year-old boy with AMoL and simple trisomy 11, showed rearrangement of MLL. He did not respond to chemotherapy, and successfully underwent bone marrow transplantation, but suffered a relapse 22 months later. Reverse transcription-polymerase chain reaction (RT-PCR) and sequencing analyses of bone marrow cells revealed a tandem duplication of MLL, and his relapse was predictable by sequential RT-PCR studies before it was clinically evident. Of 16 acute myeloid leukemia patients with trisomy 11 and rearrangement of MLL reported, our patient was the youngest in age and the only one with AMoL.

Clinical and Genetic Characteristics of Japanese Burkitt Lymphomas with or without Leukemic Presentation

To clarify the clinical and genetic features of Burkitt lymphoma with or without leukemic presentation, we have conducted clinical, cytogenetic, and genetic studies. Of 40 Japanese patients with Burkitt lymphoma examined by cytogenetic and/or fluorescence in situ hybridization analysis or Southern blot analysis usingMYC probes, 35 patients had t(8;14) translocations, and 5 had t(8;22). Breakpoints were located far upstream ofMYC in 4 (12%) of 33 tumors with t(8;14), and Epstein-Barr virus infection was found in 3 (8%) of 40 tumors. These findings are similar to those reported for non-Japanese patients with the sporadic form of Burkitt lymphoma. Clinical and genetic characteristic were compared for 30 patients presenting with lymphoma and 10 presenting with leukemia. The overall survival was shorter in aggressively treated leukemia patients than in aggressively treated lymphoma patients(P =.003); however, the incidence rates ofTP53 mutation,p16INK4a deletion, andp15INK4b deletion that were found in 6 (15%) of 40,3 (9%) of 35, and 2 (6%) of 35 tumors, respectively, were similar between the 2 subtypes. Thus, the present study has shown the different prognoses for the 2 subtypes of Burkitt lymphoma but has failed to clarify the genetic backgrounds that may explain the different outcomes.Int J Hematol. 2003;77:490-498.

Difference in effects of interferon-α and interferon-γ on the induction of differentiation of retinoic acid-treated acute myeloid leukemia cells in primary culture

Abstract We studied differentiation inducing effects of retinoic acid (RA), 1α,25-dihydroxyvitamin D 3 (D 3 ) and interferons (IFNs), alone and in combination, on fresh myeloid leukemic cells from 8 patients. RA not only induced the differentiation of leukemic cells in 5 8 cases, but potentiated differentiation by IFNs either in granulocytic or monocytic pathways. In particular, interferon-α enhanced granulocytic differentiation and interferon-γ induced mono-macrophage differentiation of promyelocytic leukemic cells in the presence of RA. Differentiation induced by D 3 , alone or in combination with IFNs, was limited in all cases. RA plus IFNs might be an effective combination for differentiation therapy for some types of myeloid leukemia.

FGF‐2 suppresses expression of nephronectin via JNK and PI3K pathways

Nephronectin (Npnt), an extracellular matrix protein, is a ligand for integrin α8β1 and is involved in the development of various organs, such as the kidneys, bones, liver, and muscles. Previously, we found that Npnt expression was inhibited by various cytokines including transforming growth factor‐β (Tgf‐β) and oncostatin M (Osm). Fibroblast growth factor (Fgf)‐2, otherwise known as basic Fgf, also plays important roles in skeletal development and postnatal osteogenesis. In this study, Npnt expression was found to be suppressed by Fgf‐2 in MC3T3‐E1 cells, an osteoblast‐like cell line, in a dose‐ and time‐dependent manners. Furthermore, Fgf‐2‐mediated NpntmRNA suppression was shown to involve the Jun N‐terminal kinase (JNK) and phosphoinositide‐3 kinase (PI3K) pathways. Together, our results suggest that FGF‐2 suppresses Npnt gene expression via JNK and PI3K pathways.

IL-1β suppresses nephronectin expression in osteoblasts via ERK1/2 and JNK

Nephronectin (Npnt), an extracellular matrix protein, is considered to play critical roles in development of various tissues and their functions. In basic science experiments, we found that interleukin-1β (IL-1β), well known to have an important role in inflammatory response, inhibited Npnt gene expression in MC3T3-E1 cells, a mouse osteoblastic cell line. The purpose of this study was to investigate mechanisms that govern the regulation of Npnt gene expression by IL-1β in osteoblasts.