Proto-oncogene expression in human normal bone marrow

We and other investigators have previously reported our findings on oncogene expression in human leukemia in an attempt to study the possible involvement of these genes in the leukemic state. An important shortcoming of these studies has been the lack of information on the expression of these genes in normal hematopoietic cells. To address this question we analyzed both the transcript size and level of expression of six oncogenes in fresh hematopoietic cells obtained from hematologically normal individuals and compared the results to those found in fresh samples obtained from patients with various forms of leukemia (acute myelogenous leukemia, acute lymphocytic leukemia, and chronic myelogenous leukemia). We found low level expression of c-myc, c-myb, c-fes, and c-raf in normal bone marrow in sharp contrast to the high levels of expression found in some forms of leukemia. C-fos was highly expressed in both normal bone marrow and certain leukemias. We were unable to detect c-sis expression in our normal samples. With the exception of c-fes, there was no variation in transcript size when comparing normal and leukemic samples. Having defined the transcript sizes and levels of expression for these proto-oncogenes in normal hematopoietic cells, we know that aberrant transcript size for the genes we have studied is not a common event in leukemias. The levels of expression, however, vary widely between normal hematopoietic cells and leukemia as well as between different types of leukemia.