THE PREDOMINANT E2F COMPLEX IN HUMAN PRIMARY HEMATOPOIETIC-CELLS AND IN AML BLASTS CONTAINS E2F-4, DP-1 AND P130

The E2F family of transcription factors are thought to play an importa nt role in the control of cell cycle progression. There is now also in creasing evidence that some family members may act as oncogenes or tum our suppressor genes. The characterization of these proteins in human primary haemopoietic cells and acute myeloid leukaemia (AML) blasts ma y thus give an insight to the molecular mechanisms governing prolifera tion and leukaemogenesis in these cells. Therefore we analysed the exp ression of E2F-DNA binding activity and the constituent proteins found in the complexes in human primary haemopoietic cells of various linea ges. We also studied blasts from 18 patients with acute myeloid leukae mia (AML). On electromobility shift assays (EMSA) a single E2F-DNA bin ding complex was detected in T cells, B cells and monocytes which was shown to contain E2F-4, DP-1 and p130, indicating that all quiescent h aemopoietic cells have the same complex. Examination of 18 AML samples by EMSA revealed the presence of E2F binding and no gross abnormaliti es were detected. An E2F-4/p130 complex was detected in representative samples of all FAB types analysed. Thus abnormalities of E2F function are unlikely to play a primary pathogenic role in AML.