OBJECTIVE: Our objective was to determine the value of frequent minimal residual disease (MRD) monitoring in acute myeloid leukemia (AML) as a robust marker of impending relapse, and whether treatment benefits patients during the MRD-positive phase of their disease. MATERIALS AND METHODS: Frequent MRD monitoring was performed in all AML treatment phases using real-time quantitative polymerase chain reaction for fusion transcripts (CBFB/MYH11; RUNX1/RUNX1T1 fusion transcripts of MLL gene) and for the Wilms' tumor (WT1) gene. A total of 2,664 samples, taken from 79 AML patients and 6 healthy volunteers, were examined. Presence of fusion gene was detected in 25 of 79 examined patients. RESULTS: Vast correlation was discovered for fusion transcripts as well as for the WT1 gene between levels in bone marrow (BM), peripheral blood, CD34(+) BM cells, and CD34(-) BM cells. WT1 expression, however, was usually positive for cases showing fusion transcripts negativity and in healthy volunteers. Moreover, no universal value of the WT1 expression could unequivocally discriminate between remission and relapse. Therefore, detection of molecular relapses relied on fusion transcripts only and was characterized by strong expression in CD34(+) cells. Considering relapsed patients, duration from molecular to hematological relapse was 8 to 79 days (median: 25.5 days). Twelve patients were treated (chemotherapy, gemtuzumab ozogamicin, or immunomodulation after allogeneic transplantation) for 21 molecular relapses and 14 responses to treatment were observed. CONCLUSIONS: Frequent quantitative monitoring of fusion transcripts is useful for reliably predicting hematological relapse in AML patients. Treatment for molecular relapse of AML can be successful.

• MeSH
• Leukemia, Myeloid, Acute diagnosis   MeSH
• Adult MeSH
• Middle Aged MeSH
• Humans MeSH
• Young Adult MeSH
• Biomarkers, Tumor analysis   MeSH
• Neoplasm Proteins analysis   MeSH
• Core Binding Factor beta Subunit analysis   MeSH
• Core Binding Factor Alpha 2 Subunit analysis   MeSH
• WT1 Proteins analysis   MeSH
• Myeloid-Lymphoid Leukemia Protein analysis   MeSH
• Recurrence MeSH
• Neoplasm, Residual diagnosis   therapy   MeSH
• Aged MeSH
• Case-Control Studies MeSH
• Translocation, Genetic MeSH
• Check Tag
• Adult MeSH
• Middle Aged MeSH
• Humans MeSH
• Young Adult MeSH
• Male MeSH
• Aged MeSH
• Female MeSH
• Publication type
• Research Support, Non-U.S. Gov't MeSH

Hematopoietic transcription factors GATA-1 and PU.1 bind each other on DNA to block transcriptional programs of undesired lineage during hematopoietic commitment. Murine erythroleukemia (MEL) cells that coexpress GATA-1 and PU.1 are blocked at the blast stage but respond to molecular removal (downregulation) of PU.1 or addition (upregulation) of GATA-1 by inducing terminal erythroid differentiation. To test whether GATA-1 blocks PU.1 in MEL cells, we have conditionally activated a transgenic PU.1 protein fused with the estrogen receptor ligand-binding domain (PUER), resulting in activation of a myeloid transcriptional program. Gene expression arrays identified components of the PU.1-dependent transcriptome negatively regulated by GATA-1 in MEL cells, including CCAAT/enhancer binding protein alpha (Cebpa) and core-binding factor, beta subunit (Cbfb), which encode two key hematopoietic transcription factors. Inhibition of GATA-1 by small interfering RNA resulted in derepression of PU.1 target genes. Chromatin immunoprecipitation and reporter assays identified PU.1 motif sequences near Cebpa and Cbfb that are co-occupied by PU.1 and GATA-1 in the leukemic blasts. Significant derepression of Cebpa and Cbfb is achieved in MEL cells by either activation of PU.1 or knockdown of GATA-1. Furthermore, transcriptional regulation of these loci by manipulating the levels of PU.1 and GATA-1 involves quantitative increases in a transcriptionally active chromatin mark: acetylation of histone H3K9. Collectively, we show that either activation of PU.1 or inhibition of GATA-1 efficiently reverses the transcriptional block imposed by GATA-1 and leads to the activation of a myeloid transcriptional program directed by PU.1.

• MeSH
• Transcriptional Activation genetics   MeSH
• Cell Differentiation genetics   MeSH
• HeLa Cells MeSH
• Histones genetics   metabolism   MeSH
• Leukemia genetics   metabolism   physiopathology   MeSH
• Humans MeSH
• RNA, Small Interfering MeSH
• Myeloid Cells metabolism   MeSH
• Cell Transformation, Neoplastic genetics   metabolism   MeSH
• Core Binding Factor beta Subunit genetics   metabolism   MeSH
• CCAAT-Enhancer-Binding Proteins genetics   metabolism   MeSH
• Proto-Oncogene Proteins genetics   MeSH
• Gene Expression Regulation, Neoplastic genetics   MeSH
• Regulatory Elements, Transcriptional genetics   MeSH
• Recombinant Fusion Proteins genetics   metabolism   MeSH
• Repressor Proteins genetics   metabolism   MeSH
• RNA Interference MeSH
• Trans-Activators genetics   MeSH
• GATA1 Transcription Factor genetics   metabolism   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Research Support, Non-U.S. Gov't MeSH
• Research Support, N.I.H., Extramural MeSH