Honoka Arai

Leukemia-Related Transcription Factor TEL Is Negatively Regulated through Extracellular Signal-Regulated Kinase-Induced Phosphorylation

ABSTRACT TEL is an ETS family transcription factor that possesses multiple putative mitogen-activated protein kinase phosphorylation sites. We here describe the functional regulation of TEL via ERK pathways. Overexpressed TEL becomes phosphorylated in vivo by activated ERK. TEL is also directly phosphorylated in vitro by ERK. The inducible phosphorylation sites are Ser213 and Ser257. TEL binds to a common docking domain in ERK. In vivo ERK-dependent phosphorylation reduces trans-repressional and DNA-binding abilities of TEL for ETS-binding sites. A mutant carrying substituted glutamates on both Ser213 and Ser257 functionally mimics hyperphosphorylated TEL and also shows a dominant-negative effect on TEL-induced transcriptional suppression. Losing DNA-binding affinity through phosphorylation but heterodimerizing with unmodified TEL could be an underlying mechanism. Moreover, the glutamate mutant dominantly interferes with TEL-induced erythroid differentiation in MEL cells and growth suppression in NIH 3T3 cells. Finally, endogenous TEL is dephosphorylated in parallel with ERK inactivation in differentiating MEL cells and is phosphorylated through ERK activation in Ras-transformed NIH 3T3 cells. These data indicate that TEL is a constituent downstream of ERK in signal transduction systems and is physiologically regulated by ERK in molecular and biological features.

Functional regulation of TEL by p38-induced phosphorylation

TEL is a nuclear phosphoprotein that belongs to a member of the ETS family transcription factors. TEL acts as a tumor suppressor and is essential for establishing hematopoiesis in neonatal bone marrow. Because TEL possesses multiple putative mitogen-activated protein (MAP) kinase phosphorylation sites, we here investigated functional regulation of TEL via stress signaling pathways. We showed that TEL becomes phosphorylated in vivo by activated p38 but not by JNK1. The constitutive and inducible phosphorylation sites were found to be Ser(22) and Ser(257), respectively. TEL bound to p38 and was directly phosphorylated in vitro by p38. In vivo p38-dependent phosphorylation reduced trans-repressional abilities of TEL through ETS-binding consensus site. These data indicate that TELs functions are potentially regulated by p38 which is activated by various kinds of stresses. TEL could be a constituent downstream of the specific MAP kinase in the signal transduction system.

Leukemia-related transcription factor TEL accelerates differentiation of Friend erythroleukemia cells.

TEL belongs to a member of the ETS family transcription factors that represses transcription of target genes such as FLI-1. Although TEL is essential for establishing hematopoiesis in neonatal bone marrow, its role in erythroid lineage is not understood. To investigate a role for TEL in erythroid differentiation, we introduced TEL into mouse erythroleukemia (MEL) cells. Overexpressing wild-type-TEL in MEL cells enhanced differentiation induced by hexamethylene bisacetamide or dimethylsulfoxide, as judged by the increased levels of erythroid-specific δ-aminolevulinate synthase and β-globin mRNAs. TEL bound to a corepressor mSin3A through the helix–loop–helix domain. A TEL mutant lacking this domain still bound to the ETS binding site, but lost its transrepressional effect. This mutant completely blocked erythroid differentiation in MEL cells. Moreover, it showed dominant-negative effects over TEL-mediated transcriptional repression and acceleration of erythroid differentiation. Endogenous TEL mRNA was found to increase during the first 3 days in differentiating MEL cells and drastically decrease thereafter. All these data suggest that TEL might play some role in erythroid cell differentiation.

Triple Philadelphia chromosomes with major-bcr rearrangement in hypotriploid erythroleukaemia.

Abstract: The Philadelphia (Ph) chromosome is observed in approximately 1% of patients with acute myeloblastic leukaemia (AML), especially subtypes M1 and M2 in the French–American–British classification. We describe here a cytogenetic and molecular investigation of a rare case with Ph‐positive AML M6 (erythroleukaemia). A 63‐yr‐old woman was diagnosed as having erythroleukaemia. Leukaemic cells were positive for CD4 and CD7 as well as CD13, CD33, CD34 and HLA‐DR. They were analyzed by G‐banding, fluorescence in situ hybridization (FISH), Southern blot and reverse transcriptase polymerase chain reaction analyses. The karyotypes at diagnosis were as follows: 61, XX, −X, −1, −2, −3, −4, −5, −7, t(9;22)(q34;q11)×2, −15, −16, −17, −18, +19, +21, +22 [3]/61, idem, −22, +der(22)t(9;22) [36]. FISH with BCR/ABL probes showed that 39% and 57% of interphase nuclei had double and triple BCR/ABL fusion signals, respectively. Chromosome analysis in complete remission showed a normal karyotype in all 20 metaphases, confirming the diagnosis as Ph positive‐acute leukaemia. FISH at relapse showed that 92% of interphase nuclei had triple fusion signals. Rearrangement of major breakpoint cluster region (M‐bcr) in the BCR gene and coexpression of p210‐type (b2a2) and p190‐type (e1a2) BCR/ABL fusion transcripts due to alternative splicing were also detected. We conclude that clonal evolution from double to triple Ph chromosomes may be implicated in the disease progression. Considering other two reported cases, Ph‐positive erythro‐leukaemia appears to be correlated with coexpression of myeloid/T‐lymphoid markers and hyperdiploidy with double or triple Ph chromosomes, although breakpoints in the BCR gene are heterogenous.

Translocation (14;19)(q32;q13) detected by spectral karyotyping and lack of BCL3 rearrangement in CD5-positive B-cell lymphoma associated with hemophagocytic syndrome.

It has been shown that some cases of B-cell non-Hodgkin lymphoma associated with a hemophagocytic syndrome (B-LAHS) have chromosomal abnormalities at 14q32 or 19q13. We report here a 64-year-old woman with B-LAHS and a complex karyotype including add(14)(q32). We applied spectral karyotyping and revealed that the add(14)(q32) was derived from a der(14)t(14;19)(q32;q13). However, rearrangement of the BCL3 gene at 19q13 could not be detected by Southern blot analysis. Our results indicate that the translocation involving 19q13 may be one of the recurrent aberrations in B-LAHS and that the molecular mechanism of t(14;19)(q32;q13) in B-LAHS appear to be different from that observed in chronic lymphocytic leukemia.

ALK-negative anaplastic large cell lymphoma with loss of CD30 expression during treatment with brentuximab vedotin.

A 59-year-old woman with anaplastic large cell lymphoma (ALCL), ALK-negative, was treated with brentuximab vedotin (BV) against relapse after 6 regimens of systemic chemotherapy and radiation. Despite achieving an initial response, skin lesions worsened after 11 courses. A skin biopsy after the development of resistance to BV confirmed loss of CD30 expression by the tumor cells, suggesting a possible cause of resistance. This case shows that down-regulation of CD30 does occur during BV treatment, resulting in resistance to this drug. Because of this possibility, in the future, expression of CD30 should be carefully monitored with extended use of BV against ALCL.

P1-255Non-Hodgkin's lymphoma of the breast: a review of 6 cases including 3 patients with a history of autoimmune diseases

Case presentation: A 56-year-old female was received the resection of retroperitoneal leiomyosarcoma in December 2011. In July 2015, CT showed multiple liver metastases, and she received the treatment with ADR as first-line chemotherapy. After two cycles of ADR, her performance status was deteriorative, so she was treated with pazopanib as second-line chemotherapy. The PFS of pazopanib was 5 months and eribulin was 2.5 months. She was then treated with trabectedin as 4th-line chemotherapy from July 2016. Liver metastases was reduced and the disease has been controlled for 7 months from administration of trabectedin. We have still treated with trabectedin.

Successful HLA-identical Unrelated Allogeneic Bone Marrow Transplantation with a very Low Dose of Stem Cells for a Patient with Chronic Myeloid Leukemia in Blast Crisis

The important factors affecting engraftment after bone marrow transplantation (BMT) include infused stem cell dose [1,2], HLA matching [3], stem cell source [4] and T-cell-depletion of graft [5]. BMT with a low dose of marrow cells is at a high risk for graft failure [1,2]. Here we describe a patient who underwent an allogeneic BMT with a very low dose of infused nucleated cells for chronic myeloid leukemia (CML) in blast crisis and achieved delayed engraftment and durable molecular remission.