Preleukemic Hematopoietic Stem Cells Identified in Acute Leukemia

A preleukemic stem cell has been discovered that may be the first step in initiating disease and also the culprit that evades therapy and triggers relapse in patients with acute myeloid leukemia (AML).

AML is an aggressive blood cancer that starts in stem cells in the bone marrow. A mutation in a gene causes preleukemic stem cells to develop that function like normal blood stem cells but grow abnormally. These cells survive chemotherapy and can be found in the bone marrow at remission, forming a reservoir of cells that may eventually acquire additional mutations, leading to relapse.

Scientists at the Princess Margaret Cancer Center (Toronto, ON, Canada) and their international collaborators carried out genomic analysis of more than 100 leukemia genes on many patient samples. Genomic DNA was subjected to limited whole-genome amplification (RepliG, Qiagen; Valencia, CA, USA) to obtain the required amount of input DNA for the SureSelect protocol (Agilent; Santa Clara, CA, USA).

Amplified genomic DNA was mechanically sheared using the M220 Focused-ultrasonicaton (Covaris; Woburn, MA, USA) and sequencing adaptors (Illumina; San Diego, CA, USA) were ligated to fragments to make a sequencing library. Droplet digital polymerase chain reaction (ddPCR) on genomic DNA and fluorescence-activated cell sorting of human stem/progenitor and mature cell populations were also carried out.

The investigators discovered that that in about 25% of AML patients, a mutation in the gene DNA (Cytosine-5-)-Methyltransferase 3 Alpha (DNMT3a) causes preleukemic stem cells to develop that function like normal blood stem cells but grow abnormally.

John Dick PhD, a professor and the senior author of the study said, “Now we have a potential tool for earlier diagnosis that may allow early intervention before the development of full AML. We can also monitor remission and initiate therapy to target the preleukemic stem cell to prevent relapse. Our study suggests that in some cases the chemotherapy does, in fact, eradicate AML; what it does not touch are the preleukemic stem cells that can trigger another round of AML development and ultimately disease relapse.”

The study was published on February 12, 2014, in the journal Nature.

Related Links:
Princess Margaret Cancer Center
Qiagen 
Covaris