EVI1 EXPRESSION ASSOCIATED WITH A 3Q26 ANOMALY IN A LEUKEMIA-CELL LINE DERIVED FROM THE BLAST CRISIS OF CHRONIC MYELOID-LEUKEMIA

Two leukemia cell lines, TS9;22 and YS9;22, were established from diff erent individuals with Philadelphia chromosome (Ph)positive chronic my eloid leukemia in blast crisis. The reverse transcript-polymerase chai n reaction (RT-PCR) technique revealed that both cell lines expressed GATA-1, GATA-2, and the stem cell leukemia (SCL) gene, consistent with a megakaryocyte lineage. Chromosome analysis revealed that TS9;22 cel ls show the Ph translocation without abnormality of chromosome 3. In c ontrast, YS9;22 cells show the Ph translocation and dic(3)(q26;p12). N orthern analysis revealed that YS9;22 cells express the EVI1 (ecotropi c virus integration-1) gene, possibly because of the chromosomal trans location in the 3q26 region; TS9;22 cells do not express EVI1. However , no rearrangements were detected over 600 kb upstream or over 900 kb downstream of EVI1 in the YS9;22 cell line, suggesting a different mec hanism of EVI1 activation from that in leukemia cells with either a t( 3;3)(q21;q26) or inv(3)(q21q26). These results indicate that EVI1 expr ession in YS9;22 cells is linked to the 3q26 abnormality and that EVI1 activation plays an oncogenic role in the blastic transformation of c hronic myeloid leukemia.