Quantitative comparison of the expression of EVI1 and its presumptive antagonist, MDS1/EVI1, in patients with myeloid leukemia

Abstract

The EVI1 gene in chromosome band 3q26 exhibits a number of properties consistent with a role as an oncogene, and its expression is activated in most myeloid leukemia patients with, as well as in a minority of patients without, 3q26 rearrangements. A splice variant of this gene, MDS1/EVI1, acts as its antagonist at least in some tissue culture assays. We established real-time quantitative reverse transcriptase polymerase chain reaction (RTQ-RT-PCR) assays for these mRNA variants to compare their expression levels in a quantitatively reliable manner. EVI1 was overexpressed to highly variable extents in all patients with, as well as in 14% of patients without, 3q26 rearrangements. In some of these samples, MDS1/EVI1 was also transcribed at elevated levels compared to those of healthy controls. However, although the induction of MDS1/EVI1 was comparable to, or higher than, that of EVI1 in three of five samples with a normal EVI1 locus, this was true for only two of 13 patients with a 3q26 aberration. We further provide preliminary evidence that the RTQ-RT-PCR assay may be useful for disease monitoring in patients overexpressing EVI1.