Core binding factor in the early avian embryo: cloning of Cbfbeta and combinatorial expression patterns with Runx1.

We have isolated the avian ortholog for CBFbeta, the common non-DNA binding subunit of the core binding factor (CBF) that has important regulatory roles in major developmental pathways. CBFbeta forms heterodimers with the DNA-binding Runx proteins and increases their affinity for DNA and their protein stability. Here, we describe the Cbfbeta expression pattern during the first 4 days of chick embryo development, with a special interest in the developing hematopoietic system. We have compared its expression pattern to that of Runx1, which is crucial for the generation of definitive hematopoietic cells, and to other hematopoietic- or endothelial-specific markers (c-Myb, Pu.1, CD45, c-Ets-1 and VE-Cadherin). Initially, Cbfbeta is widely expressed in the early mesoderm in both the yolk sac and the embryo proper, but later its expression becomes restricted to specific organs or cell types. We have found that Cbfbeta expression overlaps with Runx1 in the hematopoietic system and neural tube. The somitic and mesonephric structures, however, express Cbfbeta in the absence of detectable Runx1. Finally, Cbfbeta and Runx1 display multiple combinatorial patterns in the endoderm and in specific nerves or ganglia. Taken together, we show that Cbfbeta exhibits a dynamic expression pattern that varies according to the organ, cell type or developmental stage. By revealing multiple combinatorial patterns between Cbfbeta and Runx1, these data provide new insights into the role of CBF during early development.

[Establishment of a new method for screening of CBFB-MYH11 fusion gene in acute myeloid leukemia and its value in clinical use].

This study was purposed to establish new method for detecting CBFB-MYH11 fusion gene in acute myeloid leukemia (AML) and to evaluate its value in clinical use. All fusion types of reported CBFB-MYH11 fusion gene were defined by search of references and databank, then the primers and probes were designed on this basis, and 3 positive plasmids and negative cell line as control were established. GUSB gene was also amplified as an internal reference. The primer/probe sets were tested with 3 positive plasmids and HL-60 cDNA using quantitative real-time PCR (qPCR) assays, which were then combined as a multiplex qPCR for simultaneous detection of CBFB-MYH11 and GUSB. After optimization, the multiplex qPCR assay demonstrated both high sensitivity (10 copies for all the 3 plasmids) and high specificity. Finally, the multiplex qPCR assay was clinically evaluated with 58 AML patients, and 4 CBFB-MYH11-positive cases (6.9%) were detected, involving A type (3 cases) and J type (1 case). By comparison, the multiplex qPCR assay showed results concordant with sequencing results, and detected one case that was missed by cytogenetic analysis. It is concluded that a novel qPCR method for screening of CBFB-MYH11 fusion gene in AML is established. This method is fast, comprehensive, sensitive, specific, reliable, and should consider to be a robust tool for identification and management of AML patients with CBFB-MYH11 fusion gene.

Detection and treatment of molecular relapse in acute myeloid leukemia with RUNX1 (AML1), CBFB, or MLL gene translocations: frequent quantitative monitoring of molecular markers in different compartments and correlation with WT1 gene expression.

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.