Pp. Liu et al., IDENTIFICATION OF THE CHIMERIC PROTEIN PRODUCT OF THE CBFB-MYHII FUSION GENE IN INV(16) LEUKEMIA-CELLS, Genes, chromosomes & cancer, 16(2), 1996, pp. 77-87
An expressed gene formed by fusion between the CBFB transcription fact
or gene and the smooth muscle myosin heavy chain gene MYHI I is consis
tently detected by reverse transcription polymerase chain reaction (RT
-PCR) in patients who have acute myeloid leukemia (AML) subtype M4Eo w
ith an inversion of chromosome I Ci, We have previously shown that a C
BFB-MYHI I cDNA construct can produce a chimeric protein and transform
NIH 3T3 cells. However, the presence of the chimeric protein in patie
nt cells has not been demonstrated previously. Here, we show that such
chimeric proteins can be identified in vivo, primarily in the nuclei
of the leukemic cells, by use of antibodies against the C-terminus of
the smooth muscle myosin heavy chain and the fusion junction peptide.
A very high molecular weight protein/DNA complex is generated when nuc
lear extracts from patient cells are used in electrophoretic mobility
shift assays, as seen in NIH 3T3 cells transfected with the CBFB-MYHI
I cDNA. Immunofluorescence staining shows that the proteins are organi
zed in vivo into novel structures within cell nuclei, One isoform of t
he transcript of the CBFB-MYHI I fusion gene, containing the MHC,,, C-
terminus, was the predominant form in all five cases studied. (C) 1996
Wiley-Liss, Inc.