Nav: Home

Researchers find new way to target blood stem cell cancers

January 25, 2017

A protein-sugar molecule, CD99, occurs more frequently than normal on stem cells responsible for blood cancers, including acute myeloid leukemia (AML) and the related myelodysplastic syndromes (MDS).

This is the finding of a study led by researchers from NYU Langone Medical Center and Memorial Sloan Kettering Cancer Center, and published online Jan. 25 in Science Translational Medicine.

Building on this discovery, the study authors designed an antibody that recognizes and destroys CD99-covered leukemia cells while sparing normal blood stem cells, a finding confirmed by experiments in human cells and in mice with AML cells. Antibodies are immune system proteins that stick to a specific target, like a protein on the surface of invading bacterium. In recent years, researchers have become capable of engineering antibodies so that they target disease-related molecules.

"Our findings not only identify a new molecule expressed on stem cells that drive these human malignancies, but we show that antibodies against this target can directly kill human AML stem cells," says corresponding study author, Christopher Y. Park, MD, PhD, associate professor in the Department of Pathology at NYU Langone and its Perlmutter Cancer Center.

"While we still have important details to work out, CD99 is likely to be an exploitable therapeutic target for most AML and MDS patients, and we are working urgently to finalize a therapy for human testing," says Park.

Direct Cell Killing

Acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS) arise from abnormal stem cells that build up in bone marrow until they interfere with normal blood cell production. Patients struggle with anemia, increased risk for infection, and bleeding.

The study results are based on the understanding that cancers, like normal tissues, contain stem cells that give rise to all the other cells. Such "cancer stem cells" are known to be major drivers of many cancer types. In AML, a small group of leukemic stem cells become incapable of maturing into red or white blood cells as intended. Most leukemias respond initially to standard treatment, but relapse is common as standard treatments fail to kill leukemia stem cells, which continue to multiply.

The research team became interested in CD99 when they observed that it occurs frequently on AML and MDS cells, and then noted in the literature that CD99 is elevated in a rare bone cancer called Ewing's Sarcoma. This prompted them to see if CD99 was important in the development of these blood diseases.

When researchers examined stem cell populations from 79 AML and 24 MDS patients, they found that approximately 85 percent of stem cells in both groups expressed high levels of CD99. The levels were so high that diseased stem cells could be cleanly separated from related, normal stem cells in AML patients.

Upon confirming that CD99 was abundant on leukemia stem cells, the research team then made several CD99 antibodies, and chose to focus on the one that most effectively killed those cells. Researchers found that when the study antibody attaches itself to CD99 on the surface of a cancer stem cell, it sends a signal inside the cell that increases the activity of enzymes called SRC-family kinases.

While the team does not yet know why, the binding of their antibody to CD99, and the subsequent activation of these enzymes, causes leukemia stem cells to die. Most cells with genetic mistakes leading to cancer "sense" they are flawed and self-destruct, but CD99, so the theory goes, may be part of a mechanism that prevents this. As the antibody binds to CD99, it appears to undo this block on self-destruction.

"With the appropriate support, we believe we can rapidly determine the best antibodies for use in patients, produce them at the quality needed to verify our results, and apply for permission to begin clinical trials," says Park.

While the most common acute leukemia affecting adults (22,000 new cases each year) and expected to become more prevalent as the population ages, AML it is still relatively rare, accounting for 1.2 percent of U.S. cancer deaths. About 15,000 mostly elderly patients are diagnosed with MDS each year as well.
-end-
Along with Park, the study was led by Stephen Chung, William Eng, Wenhuo Hu, Mona Khalaj, Montreh Tavakkoli, and Ross Levine with the Human Oncology and Pathogenesis Program at Memorial Sloan Kettering Cancer Center. Also a study author was Virginia Klimek in the Leukemia Service at Memorial Sloan Kettering Cancer Center. In addition, Francine Garrett-Bakelman and Ari Melnick in the Division of Hematology and Medical Oncology at Weill Cornell School of Medicine; and Martin Carroll in the Division of Hematology and Oncology at the University of Pennsylvania, made important contributions.

Funding for the study was provided a Young Investigator Award from the Conquer Cancer Foundation of the American Society of Clinical Oncology, a U.S. Department of Defense Postdoctoral Fellow Award in Bone Marrow Failure Research (BM120096), a Fellow Scholar Award from the American Society of Hematology, a Clinical Scientist Award from the Doris Duke Charitable Foundation, a Translational Research Program Award from the Leukemia and Lymphoma Society, and a grant from the Geoffrey Beene Cancer Research Center.

NYU Langone Medical Center / New York University School of Medicine

Related Stem Cells Articles:

First events in stem cells becoming specialized cells needed for organ development
Cell biologists at the University of Toronto shed light on the very first step stem cells go through to turn into the specialized cells that make up organs.
Surprising research result: All immature cells can develop into stem cells
New sensational study conducted at the University of Copenhagen disproves traditional knowledge of stem cell development.
The development of brain stem cells into new nerve cells and why this can lead to cancer
Stem cells are true Jacks-of-all-trades of our bodies, as they can turn into the many different cell types of all organs.
Healthy blood stem cells have as many DNA mutations as leukemic cells
Researchers from the Princess Máxima Center for Pediatric Oncology have shown that the number of mutations in healthy and leukemic blood stem cells does not differ.
New method grows brain cells from stem cells quickly and efficiently
Researchers at Lund University in Sweden have developed a faster method to generate functional brain cells, called astrocytes, from embryonic stem cells.
NUS researchers confine mature cells to turn them into stem cells
Recent research led by Professor G.V. Shivashankar of the Mechanobiology Institute at the National University of Singapore and the FIRC Institute of Molecular Oncology in Italy, has revealed that mature cells can be reprogrammed into re-deployable stem cells without direct genetic modification -- by confining them to a defined geometric space for an extended period of time.
Researchers develop a new method for turning skin cells into pluripotent stem cells
Researchers at the University of Helsinki, Finland, and Karolinska Institutet, Sweden, have for the first time succeeded in converting human skin cells into pluripotent stem cells by activating the cell's own genes.
In mice, stem cells seem to work in fighting obesity! What about stem cells in humans?
This release aims to summarize the available literature in regard to the effect of Mesenchymal Stem Cells transplantation on obesity and related comorbidities from the animal model.
TSRI researchers identify gene responsible for mesenchymal stem cells' stem-ness'
Researchers at The Scripps Research Institute recently published a study in the journal Cell Death and Differentiation identifying factors crucial to mesenchymal stem cell differentiation, providing insight into how these cells should be studied for clinical purposes.
Stem cells in intestinal lining may shed light on behavior of cancer cells
The lining of the intestines -- the epithelium -- does more than absorb nutrients from your lunch.
More Stem Cells News and Stem Cells Current Events

Top Science Podcasts

We have hand picked the top science podcasts of 2019.
Now Playing: TED Radio Hour

In & Out Of Love
We think of love as a mysterious, unknowable force. Something that happens to us. But what if we could control it? This hour, TED speakers on whether we can decide to fall in — and out of — love. Guests include writer Mandy Len Catron, biological anthropologist Helen Fisher, musician Dessa, One Love CEO Katie Hood, and psychologist Guy Winch.
Now Playing: Science for the People

#542 Climate Doomsday
Have you heard? Climate change. We did it. And it's bad. It's going to be worse. We are already suffering the effects of it in many ways. How should we TALK about the dangers we are facing, though? Should we get people good and scared? Or give them hope? Or both? Host Bethany Brookshire talks with David Wallace-Wells and Sheril Kirschenbaum to find out. This episode is hosted by Bethany Brookshire, science writer from Science News. Related links: Why Climate Disasters Might Not Boost Public Engagement on Climate Change on The New York Times by Andrew Revkin The other kind...
Now Playing: Radiolab

Breaking Bongo
Deep fake videos have the potential to make it impossible to sort fact from fiction. And some have argued that this blackhole of doubt will eventually send truth itself into a death spiral. But a series of recent events in the small African nation of Gabon suggest it's already happening.  Today, we follow a ragtag group of freedom fighters as they troll Gabon's president - Ali Bongo - from afar. Using tweets, videos and the uncertainty they can carry, these insurgents test the limits of using truth to create political change and, confusingly, force us to ask: Can fake news be used for good? This episode was reported and produced by Simon Adler. Support Radiolab today at Radiolab.org/donate.