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UC San Diego Health
New research has revealed a method of targeting leukemia stem cells (LSCs) in blast crisis chronic myeloid leukemia (BC-CML).
For this study, investigators used human cells and mouse models to define the role of ADAR1, an RNA editing enzyme, in BC-CML.
The team discovered how ADAR1 promotes LSC generation and identified a small molecule that can disrupt this process to fight BC-CML.
Catriona Jamieson, MD, PhD, of the University of California, San Diego, and her colleagues described this work in Cell Stem Cell.
“In this study, we showed that cancer stem cells co-opt an RNA editing system to clone themselves,” Dr Jamieson said. “What’s more, we found a method to dial it down.”
The investigators knew that ADAR1 can edit the sequence of microRNAs. By swapping out just one microRNA building block for another, ADAR1 alters the carefully orchestrated system cells use to control which genes are turned on or off at which times.
ADAR1 is also known to promote cancer progression and resistance to therapy. But Dr Jamieson’s team wanted to determine ADAR1’s role in governing LSCs.
The investigators conducted experiments with human BC-CML cells and mouse models of BC-CML. And they found that increased JAK2 signaling and BCR-ABL1 amplification activate ADAR1 in BC-CML cells. Then, hyper-ADAR1 editing slows down microRNAs known as let-7.
Ultimately, this activity increases cellular regeneration, turning white blood cell precursors into LSCs. And LSCs promote BC-CML.
After learning how the ADAR1 system works, Dr Jamieson and her colleagues looked for a way to stop it.
By inhibiting ADAR1 with a small-molecule compound known as 8-Aza, the investigators were able to counter ADAR1’s effect on LSC self-renewal and restore let-7.
Treatment with 8-Aza reduced self-renewal of BC-CML cells by approximately 40%, when compared to untreated cells.
“Based on this research, we believe that detecting ADAR1 activity will be important for predicting cancer progression,” Dr Jamieson said.
“In addition, inhibiting this enzyme represents a unique therapeutic vulnerability in cancer stem cells with active inflammatory signaling that may respond to pharmacologic inhibitors of inflammation sensitivity or selective ADAR1 inhibitors that are currently being developed.”
