Cyclin A1 expression in leukemia and normal hematopoietic cells

Human cyclin A1 is a newly cloned, tissue-specific cyclin that is prominent ly expressed in normal testis. In this study, we showed that cyclin A1 was highly expressed in a subset of leukemia samples from patients. The highest frequency of cyclin Al overexpression was observed in acute myelocytic leu kemias, especially those that were at the promyelocyte (M3) and myeloblast (M2) stages of development. Cyclin A1 expression was also detected in norma l CD34(+) progenitor cells. The expression of cyclin A1 increased when thes e cells were stimulated to undergo myeloid differentiation in vitro. Taken together our observations suggest that cyclin A1 may have a role in hematop oiesis. High levels of cyclin A1 expression are especially associated with certain leukemias blocked at the myeloblast and promyelocyte stages of diff erentiation. (C) 1999 by The American Society of Hematology.