A SINGLE 3.7-KILOBASE MESSENGER-RNA HYBRIDIZES TO IMMEDIATE-EARLY PROMOTER-ENHANCER OF HUMAN CYTOMEGALOVIRUS IN HL-60 AND ACUTE MYELOID-LEUKEMIA CELLS

Expression of a mRNA cross-hybridized to human cytomegalovirus immediate-early gene promoter-enhancer was detected in the human promyelocytic leukemia cell line HL-60. The 0.6 kilobase of NruI/SacI DNA fragment of eukaryotic expression vector pCDM8 representing human cytomegalovirus immediate-early gene promoter-enhancer was used as the probe to hybridize with polyadenylated RNA by the Northern blot analysis. A 3.7-kilobase strand of polyadenylated RNA was visualized in the cytoplasmic fraction of HL-60 promyelocytes. In contrast, other human hematopoietic cell lines, hepatoma cells, and normal human fibroblasts did not show such a transcript by cross-hybridization. This transcript was called CMVE RNA. The expression of CMVE mRNA was also detectable in the fresh blast cells from patients with acute myeloid leukemia, and particularly from a patient with acute myeloid leukemia of the M3 type. Taken together, these findings suggest that the CMVE RNA-encoded gene plays an important role in the pathogenesis of acute promyelocytic leukemia.