EXPRESSION OF THE TRANSCRIPTION FACTOR EVI-1 IN HUMAN ERYTHROLEUKEMIACELL-LINES AND IN LEUKEMIAS

The Evi-1 proto-oncogene is a zinc finger DNA binding protein. Althoug h activation of the Evi-1 gene has been associated with chromosomal re arrangements of the 3q25-q28 region, ectopic expression of Evi-1 could also be observed in acute myelogenous leukemias and myelodysplastic s yndromes without cytogenetic abnormalities of the 3q26 locus. In this study, human erythroleukemic cell lines were screened for the expressi on of Evi-1 mRNA by northern blotting. Evi-1 was expressed in all the erythroid cell lines, whether undifferentiated (K 562, HEL, LAMA 84) o r exhibiting spontaneous terminal erythroid differentiation (KU 812, J K-1). Evi-1 mRNA levels were constant or elevated in hemoglobin-synthe sizing KU 812 or K 562 cells in response to erythropoietin or hemin tr eatment, respectively. In human acute myeloblastic leukemias (AML), 11 /30 expressed Evi-1 by RT-PCR. Among these cases, 4/6 erythroleukemias without abnormalities of the 3q25-q28 region were found positive. The presence of acidophilic erythroblasts (15-47% of bone marrow cells) a ccounted for the existence of a terminal erythroid differentiation in all Evi-1-positive AML M6, whereas one negative case was poorly differ entiated and referred to as AML M6 variant. These results suggest that Evi-1 mRNA expression can coexist with erythroid differentiation.