ABSTRACT
The TEL/AML1 chimeric gene is generated by the t(12;21) translocation in pre-B cell acute lymphoblastic leukemia. TEL/AML1 consists of the helix-loop-helix (HLH) dimerization domain from TEL and almost the entire of AML1, but loses the ETS DNA-binding domain from TEL. Dominant-negative effects of TEL/AML1 over wild-type-AML1 are believed to trigger the development of this type of leukemia. However, it could also be possible that TEL/AML1 affects wild-type-TEL's molecular and tumor suppressive functions through the HLH domain. To test this possibility, we first confirmed that TEL/AML1 associates with wild-type-TEL. TEL/AML1 neither bound to the ETS-binding consensus site nor repressed transcription through it. Regardless, this prevented wild-type-TEL-induced transcriptional repression. Moreover, TEL/AML1 concomitantly inhibited wild-type-TEL-induced growth suppression and wild-type-AML1-mediated transforming activity in NIH3T3 cells. All these data indicate that TEL/AML1 exerts dominant-interfering effects on both AML1 and TEL, and that expression of TEL/AML1 could result in inactivation of TEL's tumor suppressive functions in t(12;21)-carrying leukemia.
Subject(s)
DNA-Binding Proteins/metabolism , Epistasis, Genetic , Oncogene Proteins, Fusion/metabolism , Proto-Oncogene Proteins/metabolism , Repressor Proteins/metabolism , Transcription Factors/metabolism , Animals , COS Cells , Chlorocebus aethiops , Core Binding Factor Alpha 2 Subunit , DNA-Binding Proteins/genetics , Gene Expression Regulation/physiology , Leukemia, B-Cell/etiology , Leukemia, B-Cell/genetics , Leukemia, B-Cell/metabolism , Mice , NIH 3T3 Cells , Oncogene Proteins, Fusion/genetics , Proto-Oncogene Proteins/genetics , Proto-Oncogene Proteins c-ets , Repressor Proteins/genetics , Transcription Factors/genetics , Translocation, Genetic , ETS Translocation Variant 6 ProteinABSTRACT
21-year-old male was diagnosed as having acute lymphoblastic leukemia (ALL) in March 2001. Standard G-banding analysis revealed normal karyotype. He achieved complete remission after the first course of induction therapy and underwent allogeneic PBSCT in August 2001. However, leukemic cells appeared in the peripheral blood demonstrating complex chromosomal abnormalities with Philadelphia chromosome (Ph1) and expressing minor BCR/ABL transcripts. We thus retrospectively examined the bone marrow sample at presentation with both interphase FISH and RT-PCR methods. Surprisingly, almost all leukemic blasts at presentation turned out to possess the minor type of BCR/ABL fusion gene. In spite of the second allogeneic PBSCT, the patient died of pneumonia and graft-versus-host disease in the liver in September 2002. This case is rare in that cytogenetic analysis failed to detect Ph1 due to leukemic cells dormancy. The application of both FISH and RT-PCR studies would appear to be essential to avoid overlooking Ph1-positive ALL.
Subject(s)
Philadelphia Chromosome , Precursor Cell Lymphoblastic Leukemia-Lymphoma/genetics , Adult , Humans , Karyotyping , MaleABSTRACT
A 26-year-old woman was diagnosed as having autoimmune hemolytic anemia in September 2002. Her eosinophil count was already high (2,190/microliter) at that time. She received prednisolone therapy with a good response and was released from the treatment in April 2003. Eosinophil numbers were within the normal range under the prednisolone administration. However, they began to increase after its completion. No underlying causes for the eosinophilia were evident. When the eosinophil count reached 5,474/microliter, the patient developed massive pleural effusion as well as palpebral swelling and myalgia, leading to a diagnosis of hypereosinophilic syndrome. Re-administration of prednisolone resulted in the disappearance of these symptoms and eosinophilia. Her eosinophils seemed to have reactivated after cessation of the prednisolone therapy and infiltrated into her organs.
Subject(s)
Anemia, Hemolytic, Autoimmune/drug therapy , Hypereosinophilic Syndrome/etiology , Prednisolone/therapeutic use , Substance Withdrawal Syndrome , Adult , Female , HumansABSTRACT
Ten patients with acute myelogenous leukemia or high risk myelodysplastic syndrome who had achieved complete remission following treatment with the CAG regimen were monitored for peripheral blood WT1 expression mRNA levels. Induction therapy with the CAG regimen did not seem to be enough to lower WT1 expression levels to the normal range. In comparison with patients who received intensive chemotherapy for post-remission therapy, those who received only CAG therapy showed higher levels of WT1 expression and more easily relapsed. These data suggest that CAG therapy alone might not be sufficient to maintain complete remission and WT1 monitoring could be useful in the choice of appropriate post-remission therapy after achieving remission with the CAG regimen.
