Proto-oncogene expression in differentiating and non-differentiating chronic myelogenous leukaemia cells.

Despite the profound differences between the chronic and blastic phases of chronic myelogenous leukaemia, no differences between chronic and blastic phase cells have been described at the molecular level. Differences have been found in the levels of expression of c-myc, c-myb and p53, which fell when chronic phase cells were cultured, while the levels of expression of the genes were stable when blastic crisis cells were cultured. In contrast c-fms expression increased and MRS expression decreased after culture of chronic or blastic phase cells. The data suggest that the regulation of expression of some genes in blastic crisis cells is unaltered while that of others is disrupted. It is not known whether the failure of c-myc, c-myb and p53 expression to fall during the culture of blastic phase cells is the cause of or a reflection of the failure of these cells to differentiate.