The researchers also discovered that normal the MLL protein cooperates with the fusion proteins via chemical modifications to chromosomes that regulate what genes should be turned on or off; by increasing survival of leukemia cells; and maintaining leukemia stem cells.

"This research not only uncovers the crucial role of a normal protein key to the development of MLL, but also how the cancer cells stay alive in the first place," says Hua. The unraveling of the new, yet little-anticipated, molecular player behind MLL points to the normal MLL gene as a potential target for new therapies, partly through repressing leukemia stem cells.

Building on this discovery, Hua's team will further investigate whether mixed lineage leukemia cells are particularly "addicted" to normal MLL protein, a non-oncogene, in their growth and survival and whether normal MLL proteins specifically cooperate with other factors to sustain leukemia stem cells, with the hope of searching for an Achille's heel of this aggressive leukemia.

Source: University of Pennsylvania School of Medicine