INCREASED EVI-1 EXPRESSION IS FREQUENTLY OBSERVED IN BLASTIC CRISIS OF CHRONIC MYELOCYTIC-LEUKEMIA

Evi-1 is a transforming gene originally identified in a common integra tion site of murine leukemia retrovirus and mapped in human chromosome 3q26. It is not normally expressed in either human or murine hematopo ietic cells, but is overexpressed in retrovirus-induced murine myeloid leukemias as well as human myeloid leukemias with 3q26 abnormalities, and thus thought to be responsible for both human and murine leukemog enesis. In this study, possible involvement of the Evi-1 gene in human leukemias was evaluated by Northern blot analysis in a total of 73 pa tients with various types of leukemias. We found that increased expres sion of the Evi-1 gene was most frequently observed in patients with C ML In blastic crisis, It was found in 10 of 14 (71.0%) samples from CM L in blastic crisis, three of 15(20.0%) from acute myelocytic leukemia , three of 11 (27.3%) from MDS-derived leukemia, and one of 11 (9.1%) from acute lymphoblastic leukemia. Among 18 patients showing increased Evi-1 expression, none of 17 informative patients showed cytogenetic abnormalities involving 3q26. In addition, Southern blot analysis reve aled neither amplification nor rearrangements of the Evi-1 gene in 11 Evi-1-positive patients whose DNA samples were available. Our results suggest that increased expression of the Evi-1 gene may play an import ant role in development of human leukemias, especially in progression from chronic phase to blastic crisis of CML even without 3q26 abnormal ities.