藤原 慎一郎

Objective. Acute myeloid leukemia (AML) develops de novo or secondarily to either myelodysplastic syndrome (MDS) or anticancer treatment (therapy-related leukemia, TRL). Prominent dysplasia of blood cells is apparent in individuals with MDS-related AML as well as in some patients with TRL or even with de novo AML. The clinical entity of AML with multilineage dysplasia (AML-MLD) is likely to be an amalgamation of MDS-related AML and de novo AML-MLD. The aim of this study was to clarify, by the use of high-density oligonucleotide microarrays, whether these subcategories of AML are intrinsically distinct from each other. Materials and Methods. The AC133(+) hematopoietic stem cell-like fractions were purified from the bone marrow of individuals with de novo AML without dysplasia (n = 15), AML-MLD (n = 11), MDS-related AML (n = 11), or TRL (n = 2), and were subjected to the synthesis of cRNA which was subsequently hybridized to microarray harboring oligonucleotide corresponding to more than 12,000 probe sets. Results. We could identify many genes whose expression was specific to these various subcategories of AML. Furthermore, with the correspondence analysis/three-dimensional projection strategy, we were able to visualize the independent, yet partially overlapping, nature of current AML subcategories on the basis of their transcriptomes. Conclusion. Our data indicate the possibility of subclassification of AML based on gene expression profiles of leukemic blasts. (C) 2004 International Society for Experimental Hematology. Published by Elsevier Inc.

DNA microarray analysis has been applied to identify molecular markers of human hematological malignancies. However, the relatively low correlation between the abundance of a given mRNA and that of the encoded protein makes it important to characterize the protein profile directly, or 'proteome,' of malignant cells in addition to the 'transcriptome.' To identify proteins specifically expressed in leukemias, here we isolated AC133(+) hematopoietic stem cell-like fractions from the bone marrow of 13 individuals with various leukemic disorders, and compared their protein profiles by two-dimensional electrophoresis. A total of 11 differentially expressed protein spots corresponding to 10 independent proteins were detected, and peptide fingerprinting combined with mass spectrometry of these proteins revealed them to include NuMA (nuclear protein that associates with the mitotic apparatus), heat shock proteins, and redox regulators. The abundance of NuMA in the leukemic blasts was significantly related to the presence of complex karyotype anomalies. Conditional expression of NuMA in a mouse myeloid cell line resulted in the induction of aneuploidy, cell cycle arrest in G(2)-M phases, and apoptosis. These results demonstrate the potential of proteome analysis with background-matched cell fractions obtained from fresh clinical specimens to provide insight into the mechanism of human leukemogenesis.