© 2005 Oxford University Press
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GATA1, Cytidine Deaminase, and the High Cure Rate of Down Syndrome Children With Acute Megakaryocytic Leukemia
Affiliations of authors: Experimental and Clinical Therapeutics Program, Barbara Ann Karmanos Cancer Institute, Detroit, MI (YG, DAT, TLJ, YR, LHM, JWT); Division of Pediatric Hematology/Oncology, Children's Hospital of Michigan, Detroit, MI (MLS, SAB, YR, JWT); Children's Research Center of Michigan, Children's Hospital of Michigan, Detroit, MI (RLT); the Departments of Pharmacology (YG, LHM) and Pediatrics (RLT, YR, JWT), Wayne State University School of Medicine, Detroit, MI
Correspondence to: Dr. J. W. Taub, Children's Hospital of Michigan, 3901 Beaubien Blvd., Detroit, MI 48201 (e-mail: jtaub{at}med.wayne.edu).
Down syndrome children with acute megakaryocytic leukemia (AMkL) have higher cure rates than non-Down syndrome acute myeloid leukemia (AML) patients treated with cytosine arabinoside (ara-C). Megakaryoblasts from Down syndrome AML patients are more sensitive in vitro to ara-C than cells from non-Down syndrome AML patients. Somatic mutations in the GATA1 transcription factor have been detected exclusively and almost uniformly in Down syndrome AMkL patients, suggesting a potential linkage to the chemotherapy sensitivity of Down syndrome megakaryoblasts. Stable transfection of wild-type GATA1 cDNA into the Down syndrome AMkL cell line CMK resulted in decreased (8- to 17-fold) ara-C sensitivity and a threefold-lower generation of the active ara-C metabolite ara-CTP compared with that for mock-transfected CMK cells. High intracellular levels of uridine arabinoside (ara-U) (an inactive ara-C catabolite generated by cytidine deaminase) and cytidine deaminase transcripts were detected in GATA1-transfected CMK sublines, whereas no ara-U was detected in mock-transfected cells. Cytidine deaminase transcripts were a median 5.1-fold (P = .002) lower in Down syndrome megakaryoblasts (n = 16) than in blast cells from non-Down syndrome patients (n = 56). These results suggest that GATA1 transcriptionally upregulates cytidine deaminase and that the presence or absence of GATA1 mutations in AML blasts likely confers differences in ara-C sensitivities due to effects on cytidine deaminase gene expression, which, in turn, contributes to the high cure rate of Down syndrome AMkL patients.
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