The expression pattern of the AML1 gene in non-Hodgkin's B-cell lymphomas and normal B lymphocytes

We have studied the expression of the three human acute myeloid leukemia (A ML) genes in primary samples of non-Hodgkin's B-cell lymphomas in which tra nslocations involving these loci were not present. We found a widespread ex pression of the three AML genes in all the lymphoma samples as well as in t he purified normal B-lymphocytes, Thus, the presence of the three mRNAs "pe r se" does not: allow the identification of the pathological status. Howeve r, AML1 showed a different transcription pattern in the neoplastic tissues with respect to the normal B-cells, The AML1b isoform proved to be peculiar to this lymphoma. Our data support the idea that qualitative and quantitat ive alterations of AML1 gene expression deriving from deregulating mechanis ms other than translocations may be involved in this malignancy. The usage of two differently regulated promoters driving the expression of the transc ripts AML1b and AML1c may be one of these mechanisms. Finally, we report th e presence of a new alternatively spliced transcript in normal B-cells, (C) 2000 Academic Press.