ABSTRACT
Retroviral insertional mutagenesis in BXH2 mice commonly induces myeloid leukemias. One of the most frequently involved genes in experimental studies is Meis 1. In contrast to other genes in murine models, Meis 1 has not been affected by recurrent chromosomal translocations or point mutations in human leukemias. We found a constant downregulation of the Meis 1 gene mRNA in AML1-ETO acute myeloid leukemias and in those cases harboring in frame mutations in the bZIP domain of CEBPalpha. The absence of the Meis 1 mRNA was not caused by inactivating point mutations in the coding sequence. Promoter hypermethylation was present in more than half of the cases (9/14), including samples obtained from the widely employed Kasumi-1 cell line. Double treatment with 5-Aza-2'-deoxycytidine and trichostatin A of the Kasumi-1 cell line partially reverses Meis 1 inhibition. HoxA9 levels were also low. In a cell line model (U937 Tet AML1-ETO), AML1-ETO expression was not associated with Meis 1 suppression at 72 h. Nevertheless, Meis 1 repression is dependent on the AML1-ETO transcript levels in treated leukemic patients. Chimeric products that arise from chromosomal translocations may be associated with locus-specific epigenetic inactivation. It remains to be investigated when this methylation process is acquired and which are the basic mechanisms underlying these molecular events in AML1-ETO and CEBPalpha-mutated AML.
Subject(s)
Azacitidine/analogs & derivatives , DNA Methylation , Homeodomain Proteins/genetics , Leukemia, Myeloid/genetics , Neoplasm Proteins/genetics , Oncogene Proteins, Fusion , Promoter Regions, Genetic/genetics , Transcription Factors , Acute Disease , Adult , Azacitidine/pharmacology , Bone Marrow , Case-Control Studies , Cell Line, Tumor , Core Binding Factor Alpha 2 Subunit , DNA Methylation/drug effects , Decitabine , Down-Regulation/drug effects , Homeodomain Proteins/physiology , Humans , Hydroxamic Acids/pharmacology , Leukemia, Myeloid/drug therapy , Myeloid Ecotropic Viral Integration Site 1 Protein , Neoplasm Proteins/physiology , RNA, Messenger/analysis , RUNX1 Translocation Partner 1 ProteinSubject(s)
DNA-Binding Proteins/genetics , Leukemia, Myeloid/genetics , Mutation/genetics , Myelodysplastic Syndromes/genetics , Neoplasm Proteins/genetics , Proto-Oncogene Proteins , Transcription Factors/genetics , Acute Disease , Adolescent , Adult , Aged , Aged, 80 and over , Child , Core Binding Factor Alpha 2 Subunit , DNA Mutational Analysis , Female , Humans , Leukemia, Myeloid/diagnosis , Male , Middle Aged , Myelodysplastic Syndromes/diagnosis , Polymorphism, Single-Stranded ConformationalABSTRACT
BACKGROUND AND OBJECTIVES: The hematopoietic system is controlled by growth factors (cytokines) which can influence cell survival, proliferation, differentiation and functional activation. The study of cytokine receptor expression by flow cytometry could allow us to differentiate between normal and tumoral cells. DESIGN AND METHODS: We analyzed the expression of the interleukin-3 (IL-3) receptor a chain (CD123) in 22 normal samples and in a wide panel of hematologic malignancies using flow cytometry. We found that CD123 was expressed in the myeloid progenitor subpopulation but in contrast, normal lymphoid progenitors lacked CD123. We analyzed the CD123 expression pattern in 64 patients with acute leukemia, 45 with acute myeloid leukemia (AML) and 19 with acute lymphocytic leukemia (ALL) (13 B-cell lineage ALL and 6 T-cell lineage ALL). RESULTS: All the AML cases except two patients with M7 and all the B-cell lineage ALL patients were CD123 positive. In contrast, all the T-cell lineage ALL cases tested were CD123 negative. We also studied the CD123 expression pattern in 122 patients with a B-cell chronic lymphoproliferative disease (B-CLPD). CD123 was positive in three situations: 1) typical cases of hairy cell leukemia showed a specific, strong CD123 expression, 2) a subgroup of atypical chronic lymphocytic leukemia with a marked CD11c expression was also CD123 positive, and finally 3) transformed B-CLPD showed the phenomenon of transition from CD123 negativity to CD123 positivity simultaneuosly with morphologic changes. INTERPRETATION AND CONCLUSIONS: In summary, our data show high expression of IL-3 receptor a chain in hematologic malignancies. Given the high frequency of CD123 reactivity in blast cells in contrast to in normal precursors, this antigen could be applied to the study of minimal residual disease in acute leukemia. CD123 is expressed with a characteristic pattern in cases of hairy cell leukemia.
Subject(s)
Hematologic Neoplasms/metabolism , Receptors, Interleukin-3/analysis , Acute Disease , Biomarkers, Tumor/analysis , Flow Cytometry , Hematologic Neoplasms/diagnosis , Humans , Interleukin-3 Receptor alpha Subunit , Leukemia/diagnosis , Leukemia/metabolism , Receptors, Interleukin-3/metabolismSubject(s)
Burkitt Lymphoma/genetics , DNA-Binding Proteins/genetics , Repressor Proteins/genetics , Adolescent , Child , Child, Preschool , Female , Gene Frequency , Gene Rearrangement, B-Lymphocyte , Humans , Male , Proto-Oncogene Proteins c-ets , Recurrence , Sequence Deletion , ETS Translocation Variant 6 ProteinABSTRACT
Follicular lymphoma (FL) is a specific entity defined by characteristic histology, phenotype and molecular rearrangements. Classically, reactivity for CD19, CD10, and strong positivity for the surface light chain immunoglobulin (SIg) are considered to be phenotypic signs typically expressed in FL. In practice, this pattern is difficult to identify since most neoplastic cells analysed by flow cytometry (FC) show weak intensity for CD19-Pe/Cy5 and for SIg and negativity for CD10-FITC. We used triple antigen combinations including two monoclonal antibodies (MoAbs) against CD10 (CD10-FITC and CD10-Pe/Cy5) and a long-distance polymerase chain reaction (PCR) approach to establish the phenotypic pattern of neoplastic cells carrying t(14;18)(q32;q21). Neoplastic cells showed the following immunophenotype: stronger reactivity against CD20 than against CD19, positivity for CD22 and SIg and negativity for CD5, CD11c and CD10-FITC. Characteristically, CD10-Pe/Cy5 was expressed in all the samples with positive bcl-2/JH rearrangements. In FL, there was a high correlation between histologic diagnosis and reactivity against CD10-Pe/Cy5 (96% cases). In diffuse large cell lymphomas (DLCL), CD10-Pe/Cy5 identified positive cases with t(14;18)(q32;q21) chromosomal translocation, whereas Burkitt lymphomas showed all cases reactivity against CD10-Pe/Cy5. In conclusion, CD10-Pe/Cy5 is a useful antibody for identifying neoplastic cells carrying t(14;18)(q32;q21) in FL and DLCL. In combination with other MoAbs, anti-CD10 (HI10a, Cy-Chrome) can be used to identify a characteristic phenotypic profile of FL against other lymphoproliferative disorders.
Subject(s)
Antibodies, Monoclonal , Flow Cytometry/methods , Lymphoma, Follicular/diagnosis , Neprilysin/immunology , Adult , Chromosomes, Human, Pair 14 , Diagnosis, Differential , Gene Rearrangement/genetics , Genes, bcl-2/genetics , Humans , Immunophenotyping , Lymphoma, Follicular/genetics , Lymphoma, Follicular/pathology , Polymerase Chain Reaction , Translocation, GeneticABSTRACT
BACKGROUND AND OBJECTIVES: Lineage classification needs to be established before starting chemotherapy in acute leukemias. In some cases, mixed populations can be found and these are differentiated by antigenic expression patterns. DESIGN AND METHODS: We report the case of a patient with acute myelogenous leukemia whose relapse was classified as T-acute lymphoblastic leukemia (T-ALL). RESULTS: Flow cytometry analysis at diagnosis enabled us to identify a minor T-cell subclone which progressively increased and became dominant at relapse. There were no changes at cytogenetic and molecular levels. INTERPRETATION AND CONCLUSIONS: This case illustrates the usefulness of multiparametric flow cytometry for assessing minor leukemic populations.
