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Molecular pathway eyed as trigger for deadly leukemia

DNA mutation found to disrupt cellular function in patients with acute myeloid leukemia.

Norbert Reich, UC Santa Barbara

Researchers at UC Santa Barbara have discovered a molecular pathway that may explain how a particularly deadly form of cancer develops. The discovery may lead to new cancer therapies that reprogram cells instead of killing them. The findings are published in a recent paper in the Journal of Biological Chemistry.

The UC Santa Barbara research team described how a certain mutation in DNA disrupts cellular function in patients with acute myeloid leukemia (AML). The researchers were prompted to study this process by another research team’s discovery that AML patients have a mutation in a certain enzyme, which was reported in the New England Journal of Medicine. The enzyme is a protein called DNMT3A, which leads to changes in how the DNA of AML patients is methylated, or “tagged.” Norbert Reich, professor in the Department of Chemistry and Biochemistry at UC Santa Barbara, was already studying that particular enzyme with his research group, so they began to study the disease process of AML at the cellular level.

Reich explained that tagging is a way of reading DNA at the cellular level. This falls within an area of study called epigenetics, a process that occurs “on top” of genetics. Each person has approximately 200 types of cells, all with the same DNA, and these must be controlled in different ways. “There is an enzyme — a protein — that tags DNA and controls which of the genes in your cells, your DNA, gets turned on and off,” said Reich. “So you have 20,000 genes, and you have to control them differently in your brain than in your liver.”

Reich explained that there is current interest in this broader field of epigenetics as a direction for the treatment of cancer. “There’s definitely the idea that this may be a new way of developing therapeutics, because you don’t have to kill the cancer cell,” said Reich. “Almost every cancer therapy that’s out there works on the principle that a cancer cell needs to be killed.”

With epigenetics, instead of only having DNA sequence coding for certain genes, there is an epigenetic process, with another layer of information on top of the genetic process. In this case, that information is the tagging by the methyl groups.

“If you really think about it, this is part of the answer as to how your cells can be so different and yet they all have the same DNA,” said Reich. “You have the same genome in every one of your cells, but you do not have the same epigenome, which is basically the methylation pattern, the tagging pattern. That is different in every type of your cells. And the way this relates back to cancer, with leukemia, in those patients, the tagging is messed up. The patterns are not correct. Our big contribution to that is we’ve explained how the mutations in the enzyme could lead to that disruption of the tagging pattern.”

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